REVIEW | doi:10.20944/preprints202107.0030.v1
Subject: Life Sciences, Biochemistry Keywords: Crop, CRISPR/Cas9; Resistance; RNA interference; Stress
Online: 1 July 2021 (14:13:20 CEST)
With the rapid population growth, there is an urgent need for innovative crop improvement approaches to meet the increasing demand for food. Classical crop improvement approaches involve, however, a backbreaking process that cannot equipoise with increasing crop demand. RNA based approaches i.e. RNAi-mediated gene regulation and site-specific nuclease based CRISPR/Cas9 system for gene editing has made advances in the efficient targeted modification in many crops for the higher yield and resistance to diseases and different stresses. In functional genomics, RNA interference (RNAi) is a propitious gene regulatory approach that plays a significant role in crop improvement by permitting down-regulation of gene expression by small molecules of interfering RNA without affecting the expression of other genes. Gene editing technologies viz. clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein (CRISPR/Cas) have appeared prominently as a powerful tool for precise targeted modification of nearly all crops genome sequence to generate variation and accelerate breeding efforts. In this regard, the review highlights the diverse roles and applications of RNAi and CRISPR/Cas9 system as powerful technologies to improve agronomically important plants to enhance crop yields and increase tolerance to environmental stress (biotic or abiotic). Ultimately, these technologies can prove to be important in view of global food security and sustainable agriculture.
ARTICLE | doi:10.20944/preprints202105.0422.v1
Subject: Medicine & Pharmacology, Allergology Keywords: genome editing; CRISPR; Cas9; in vivo editing
Online: 18 May 2021 (11:27:46 CEST)
The development of CRISPR associated proteins, such as Cas9, has led to increased accessibility and ease of use in genome editing. However, additional tools are needed to quantify and identify successful genome editing events in living animals. We developed a method to rapidly and quantitatively monitor gene editing activity non-invasively in living animals that also facilitates confocal microscopy and nucleotide level analyses at the end of study. Here we report a new CRISPR “footprinting” approach to activate luciferase and fluorescent proteins in mice as a function of gene editing. This system is based on experience with our prior Cre-detector system and is designed for Cas editors able to target LoxP including gRNAs including SaCas9 and ErCas12a [1, 2]. These CRISPRs cut specifically within LoxP, an approach that is a departure from previous gene editing in vivo activity detection techniques that targeted adjacent stop sequences. In this sensor paradigm, CRISPR activity was monitored non-invasively in living Cre reporter mice (FVB.129S6(B6)-Gt(ROSA)26Sortm1(Luc)Kael/J and Gt(ROSA)26Sortm4(ACTB-tdTomato,-EGFP)Luo/J, which will be referred to as LSL and mT/mG throughout the paper) after intramuscular or intravenous hydrodynamic plasmid injections, demonstrating utility in two diverse organ systems. The same genome-editing event was examined at the cellular level in specific tissues by confocal microscopy to determine the identity and frequency of successfully genome-edited cells. Further, SaCas9 induced targeted editing at efficiencies that were comparable to Cre recombinase demonstrating high effective delivery and activity in a whole animal. This work establishes genome editing tools and models to track CRISPR editing in vivo non-invasively and to fingerprint the identity of targeted cells. This approach also enables similar utility for any of the thousands of previously generated LoxP animal models.
REVIEW | doi:10.20944/preprints202101.0212.v1
Online: 12 January 2021 (10:14:46 CET)
The constitutively active tyrosine kinase BCR/ABL1 oncogene plays a key role in human chronic myeloid leukemia development and disease maintenance, and determines most of the features of this leukemia. For this reason, tyrosine kinase inhibitors are the first-line treatment, offering most patients a life expectancy like that of an equivalent healthy person. However, since the oncogene is not destroyed, lifelong oral medication is essential, even though this trigger adverse effects in many patients. Furthermore, leukemic stem cells remain quiescent and resistance is observed in approximately 25% of patients. Thus, new therapeutic alternatives are still needed. In this scenario, the emergence of CRISPR technology can offer a definitive treatment based on its capacity to disrupt coding sequences. This review describes CML disease and the main advances in the genome-editing field by which it may be treated in the future.
CONCEPT PAPER | doi:10.20944/preprints202003.0321.v1
Subject: Life Sciences, Biotechnology Keywords: bookmark; CRISPR/Cas9; complementation; clostridium; knock-out
Online: 23 March 2020 (00:50:23 CET)
Phenotypic complementation of gene knock-outs is an essential step in establishing function. Here we describe a simple strategy for ‘gold standard’ complementation in which the mutant allele is replaced in situ with a wild type (WT) allele in a procedure that exploits CRISPR/Cas9. The method relies on the prior incorporation of a unique 24 nucleotide (nt) ‘bookmark’ sequence into the mutant allele to act as a guide RNA target during its Cas9-mediated replacement with the WT allele. The bookmark comprises a 23 nt Cas9 target sequence plus an additional nt to ensure the deletion is in-frame. Here, bookmarks are tailored to Streptococcus pyogenes CRISPR/Cas9, but could be designed for any CRISPR/Cas system. For proof of concept, 9 bookmarks were tested in Clostridium autoethanogenum. Complementation efficiencies reached 91%. As complemented strains are indistinguishable from their progenitors, concerns over contamination may be satisfied by incorporation of ‘watermark’ sequences into the complementing genes.
REVIEW | doi:10.20944/preprints202001.0191.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: hybrid vigor; flowering plants; apomixis; CRISPR/Cas9
Online: 17 January 2020 (10:30:45 CET)
The hybrid seeds of several important crops with supreme qualities, including yield, biotic and abiotic stress tolerance, have been cultivated from decades. Thus far, a major challenge with hybrid seed, it does not hold ability to produce plants with same qualities over subsequent generations. Apomixis exist naturally an asexual mode of reproduction in flowering plants via avoiding meiosis and ultimately leads to seed production. Apomixis possess potential to preserve hybrid vigor for multiple generations for economically important plant genotypes. The evolution and genetics of asexual seed production is unclear and need much more efforts to find its genetic architecture. To fix hybrid vigor synthetic apomixis has been suggested an alternative. The development of MiMe (Mitosis instead of Meiosis) genotypes are utilized further for clonal gametes production. However, the identification and parental origin of genes responsible for synthetic apomixis are less known and need further understanding. Genome modifications utilizing genome editing technologies (GETs) like clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (cas9) a reverse genetics tool has paved way to utilize emerging technologies in plant molecular biology. From the last decade, several genes in important crops have been successfully edited. The vast availability of GETs has made the functional genomics studies easy to conduct in crops important for food security. The disruption of expression of genes specific to egg cell MATRILINEAL (MTL) or BABY BOOM1 (BBM1) through CRISPR/Cas genome editing system can promote haploid plants. The establishment of synthetic apomixis by engineering MiMe genotype by genome editing BBM1 expression or disruption of MTL leads toward clonal seed production. In present review, we discussed the current development in plants by utilizing CRISPR/Cas9 technology and its possibility of promoting apomixis in crops to preserve hybrid vigour. In addition to this, genetics, evolution, epigenetic modifications and strategy for MiMe genotype development has been discussed in detail.
ARTICLE | doi:10.20944/preprints202211.0173.v1
Subject: Biology, Plant Sciences Keywords: aconitate hydratase; CRISPR/Cas9; male sterility; seedless tomato
Online: 9 November 2022 (10:01:29 CET)
Tomato (Solanum lycopersicum) is one of the most cultivated vegetables in the world due to its consumption in a large variety of raw, cooked, or processed foods. Tomato breeding and productivity highly depend on the use of hybrid seeds and their higher yield, environmental adaption, and disease tolerance. However, the emasculation procedure during hybridization raises tomato seed production costs and labor expenses. Using male sterility is an effective way to reduce the cost of hybrid seeds and ensure cultivar purity. Recent developments in CRISPR genome editing technology enabled tomato breeders to investigate the male sterility genes and to develop male-sterile tomato lines. In the current study, the tomato Acotinase (SlACO) gene family was investigated via in-silico tools and functionally characterized with CRISPR/Cas9-mediated gene disruption. Genome-wide blast and HMM search represented two SlACO genes located on different tomato chromosomes. Both genes were estimated to have a segmental duplication in the tomato genome due to their identical motif and domain structure. One of these genes, SlACO2, showed a high expression profile in all generative cells of tomato. Therefore, the SlACO2 gene was targeted with two different gRNA/Cas9 construct to identify their functional role in tomato. The gene was mutated in a total of 6 genome-edited tomato lines, 2 of which were homozygous. Surprisingly, pollen viability was found to be extremely low in mutant plants compared to their wild-type (WT) counterparts. Likewise, the number of seeds per fruit also sharply decreased more than fivefold in mutant lines (10-12 seed) compared to that in WT (67 seed). The pollen shape, anther structures, and flower colors/shapes were not significantly varied between the mutant and WT tomatoes. The mutated lines were also subjected to salt and mannitol-mediated drought stress to test the effect of SlACO2 on abiotic stress tolerance. The results of the study indicated that mutant tomatoes have higher tolerance with significantly lower MDA content under stress conditions. This is the first CRISPR-mediated characterization of ACO genes on pollen viability, seed formation, and abiotic stress tolerance in tomato.
ARTICLE | doi:10.20944/preprints202109.0250.v1
Online: 15 September 2021 (09:16:39 CEST)
Folic acid, one of the 13 essential vitamins, plays an important role in cardiovascular development. Mutations in folic acid synthesis gene 5,10-methylenetetrahydrofolate reductase (MTHFR) is significantly associated with the occurrence of congenital heart disease. However, the mechanisms underlying the regulation of cardiac development by mthfr gene are poorly understood. Here, we exposed zebrafish embryos to excessive folate or folate metabolism inhibitors. And we established a knock-out mutant of mthfr gene in zebrafish by using CRISPR/Cas9. The zebrafish embryos of insufficient or excessive folic acid, and mthfr-/- mutant all gave rise to early pericardial edema and cardiac defect at 3 days after fertilization(dpf). Furthermore, the folic acid treated embryos showed abnormal movement at 5dpf. The expression levels of cardiac marker genes hand2, gata4 and nppa changed in the abnormality of folate metabolism embryos and mthfr-/- mutant, and there is evidence that they are related to the change of methylation level caused by the change of folate metabolism. In conclusion, our study provides a novel model for the in-depth study of MTHFR gene and folate metabolism. And our results reveal that folic acid has a dose-dependent biphasic effect on early cardiac development.
ARTICLE | doi:10.20944/preprints202003.0437.v2
Subject: Life Sciences, Biochemistry Keywords: antivirals; broad-spectrum; CRISPR; Cas9; SARS; COVID-19
Online: 8 January 2021 (13:53:55 CET)
All RNA viruses deliver their genomes into target host cells through processes distinct from normal trafficking of cellular RNA transcripts. The delivery of viral RNA into most cells hence triggers innate antiviral defenses that recognize viral RNA as foreign. In turn, viruses have evolved mechanisms to subvert these defenses, allowing them to thrive in target cells. Therefore, drugs activating defense to exogenous RNA could serve as broad-spectrum antiviral drugs. Here we show that transcriptional signatures associated with cellular responses to the delivery of a non-viral exogenous RNA sequence into human cells predict small molecules with broad-spectrum antiviral activity. In particular, transcriptional responses to the delivery of Cas9 mRNA into human hematopoietic stem and progenitor cells (HSPCs) highly matches those triggered by small molecules with broad-spectrum antiviral activity such as emetine, homoharringtonine, pyrvinium pamoate and anisomycin, indicating that these drugs are potentially active against other RNA viruses. Furthermore, these drugs have been approved for other indications and could thereby be repurposed to novel viruses. We propose that the antiviral activity of these drugs to SARS-CoV-2 should therefore be determined as they have been shown as active against other coronaviruses including SARS-CoV-1 and MERS-CoV. Indeed, two of these drugs- emetine and homoharringtonine- were independently shown to inhibit SARS-CoV-2 as this article was in preparation. These drugs could also be explored as potential adjuvants to COVID-19 vaccines in development due to their potential effect on the innate antiviral defenses that could bolster adaptive immunity when delivered alongside vaccine antigens.
ARTICLE | doi:10.20944/preprints201904.0031.v1
Subject: Life Sciences, Biochemistry Keywords: Rett syndrome; MeCP2; CRISPR/cas9; transcriptome; calcium ion
Online: 2 April 2019 (12:28:17 CEST)
Objective: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in MeCP2, a transcription factor. MeCP2 mutations cause abnormal expression of downstream genes and eventually lead to brain dysfunction. The role of MeCP2 in brain neural development remains unclear. To further elucidate this role, a MeCP2-null rat model was created with the CRISPR/cas9 system. Method: A MeCP2-cas9 vector was constructed and then microinjected into fertilized rat ova in vitro. Two mutations by CRISPR/cas9 were confirmed to cause deletions in exon 2 of MeCP2 via DNA sequencing, and protein expression was measured by Western blotting. Transcriptome data for three brain tissues, the cerebellum, cerebral cortex and hippocampus, were obtained via next-generation sequencing. Results: MeCP2-null rats were successfully obtained, and preliminary analysis showed that the MeCP2-null rats exhibited motor dysfunction and anxious and depressed behaviour. In addition, differentially expressed genes (DEGs) were identified in the three MeCP2-null brain tissues compared to wild-type rat brain tissues. In the rat cerebellum, 388 downregulated DEGs were mainly involved in the calcium ion signalling pathway and the PI3K-Akt signalling pathway. In the cerebral cortex, 386 upregulated DEGs were primarily involved in intracellular signal transduction, protein phosphorylation and the MAPK signalling pathway. In the hippocampus, the DEGs were related to the MAPK signalling pathway. Conclusion: We constructed a MeCP2-null rat model with unique features with CRISPR/cas9 technology to study RTT and analysed DEGs in three rat brain tissues to highlight potential targets for the development of new medicines.
REVIEW | doi:10.20944/preprints202108.0387.v1
Online: 18 August 2021 (14:21:46 CEST)
Novel Cellular Immunotherapy with engineered T cells has improved cancer treatment and established therapeutic promises to prevent tumor formation in clinical studies. Due to certain restrictions and difficulties, CAR and TCR T cells therapies were inadequate at points. CRISPR Cas9 genome-editing tool has a significant potential for these two cell-based therapies. As a specialized gene-editing technique, CRISPR Cas9 is used to repair genetic alternation with minimum damage. It is used as an adjunct to Immunotherapy to stimulate a more robust immune response. CRISPR has long outpaced other target-specific genome editing methods such as ZFNs and TALEN due to its high efficiency, competence in targeting, and stable operating condition. CRISPR can overcome the two major drawbacks of universal CAR T cells: allorejection and graft-vs-host disease. TCR-based T cell treatment can reduce inappropriate binding between endogenous and transgenic TCR, resulting in a reduction of severe toxicity. The CAR and TCR T based cell therapies uphold an excellent future for tumor malignancies This article has elucidated the administration of CRISPR Cas9 in Novel Cellular Immunotherapy, CAR, and TCR T cell therapy. However, this article did not fail to observe this technology's ethical concerns, limitations, and challenges. Furthermore, the article compares CRISPR-mediated allogeneic CAR T cell to TCR-T cell therapy.
ARTICLE | doi:10.20944/preprints202106.0357.v1
Subject: Life Sciences, Biochemistry Keywords: CYP1B1; craniofacial development; CRISPR/Cas9; Congenital glaucoma; knockout zebrafish.
Online: 14 June 2021 (11:53:54 CEST)
CYP1B1 loss-of-function (LoF) is the main known genetic alteration present in recessive primary congenital glaucoma (PCG), an infrequent disease characterized by delayed embryonic development of the ocular iridocorneal angle and caused by poorly understood molecular mechanisms. To model CYP1B1 LoF underlying PCG, we developed a cyp1b1 knockout (KO) zebrafish line using CRISPR/Cas9 genome editing. This line carries the c.535_667del frameshift mutation that results in a 72% mRNA reduction with residual mRNA predicted to produce an inactive truncated protein (p.(His179Glyfs*6)). Craniofacial defects and jaw maldevelopment were observed in 23% of somatic mosaic F0 crispant larvae (144 hpf). These early phenotypes were not detected in KO F3 larvae (144 hpf) but 27% of adult fishes (4 months) showed uni or bilateral craniofacial alterations, indicating the existence of incomplete penetrance and variable expressivity. These phenotypes increased to 86% in the adult offspring of inbred progenitors with craniofacial defects. No glaucoma-related phenotypes were observed in the cyp1b1 mutants. Transcriptomic analyses of the offspring (7dpf) of KO cyp1b1 progenitors with adult-onset craniofacial defects revealed that differentially expressed genes were functionally enriched in groups related with extracellular matrix and cell adhesion, cell growth and proliferation, lipid metabolism (retinoids, steroids, and fatty acids, and oxidation-reduction processes which included several cytochrome P450 genes) and inflammation. In summary, this study shows the complexity of phenotypes and molecular pathways associated with cyp1b1 LoF, with species-dependency, and provides evidence for dysregulation of extracellular matrix gene expression as one of the mechanisms underlaying pathogenicity associated with cyp1b1 disruption.
REVIEW | doi:10.20944/preprints202011.0264.v1
Subject: Biology, Anatomy & Morphology Keywords: Bioethanol; Kluyveromyces marxianus; Omics technologies; gTME, and CRISPR-Cas9
Online: 9 November 2020 (08:38:20 CET)
Bioethanol has been considered as an excellent alternative to fossil fuels since it importantly contributes to the reduced consumption of the crude oil and to the alleviation of environmental pollution . Up to now, the baker yeast Saccharomyces cerevisiae is the most common eukaryotic microorganism used in ethanol production. The inability of S. cerevisiae to grow on pentoses, however, hinders its effective growth on plant biomass hydrolysates, which contain large amounts of C5 and C12 sugars. The industrial-scale bioprocessing requires high temperature bioreactors, diverse carbon sources, and the high titer production of volatile compounds . These criteria indicate that the search for alternative microbes possessing useful traits that meet the required standards of bioethanol production is necessary. Compared to other yeasts, Kluyveromyces marxianus has several advantages over the others, e.g. it could grow on a broad spectrum of substrates (C5, C6 and C12 sugars) , tolerate to high temperature, toxin [4,5] and a wide range of pH values , and produce volatile short-chain ester . K. marxianus also shows a high ethanol production rate at high temperature and is a Crabtree-negative species . These attributes make K. marxianus a promise as an industrial host for the biosynthesis of biofuels and other valuable chemicals.
Subject: Life Sciences, Molecular Biology Keywords: BE4; CRISPR-Cas9; Tyr; cytosine base editing; mouse model
Online: 30 December 2019 (11:16:30 CET)
Most human genetic disease arises from point mutations. These genetic diseases can theoretically be corrected by gene therapy but clinic practice is still far from mature. Nearly half of the pathogenic single-nucleotide polymorphisms (SNPs) are caused by G:C>A:T or T:A>C:G base changes. The best current methods to repair these changes are by base editing without footprint using recently developed CRISPR-Cas9 technology by David Liu’s lab. These base editing methods have been confirmed with precision and efficiency in cultured mammalian cells, but it is barely confirmed and the efficiency is still very low. Animal models are important in dissecting pathogenic mechanism for human genetic diseases and efficacy testing of base correction in vivo. Cytidine base editor BE4 is a newly developed version of cytidine base editing system that converts cytidine (C) to uridine (U) in cultured mammalian cells but has not been proven in vivo. In this study, we have tested this system in cells to inactivate GFP gene and in mice by introducing single-base substitution that leads to a stop codon in tyrosinase gene. High percentage albino coat-colored mice were obtained from black coat-colored donor zygotes after pronuclei microinjection. Sequencing results showed that expected base changes were obtained with high precision and efficiency (56.25%). There are no off-targeting events identified in predicted off-target sites. Results confirm BE4 system can work in vivo with high precision and efficacy, and has great potentials in clinic to repair human genetic mutations.
ARTICLE | doi:10.20944/preprints202201.0211.v1
Subject: Biology, Plant Sciences Keywords: microalgae; CRISPR/Cas9; gene editing; spermidine; SPD1; auxotrophy; selectable marker
Online: 14 January 2022 (11:55:22 CET)
Biotechnological application of the green microalga Chlamydomonas reinhardtii hinges on the availability of selectable markers for effective expression of multiple transgenes. However, biological safety concerns limit the establishment of new antibiotic resistance genes and until today, only few auxotrophic markers exist for C. reinhardtii. The recent improvements in gene editing via CRISPR/Cas9 allows directed exploration of new endogenous selectable markers. Since editing frequencies with CRISPR/Cas9 techniques are often low, the Cas9-sgRNA ribonucleoprotein (RNP) delivery protocol was strategically optimized by applying nitrogen starvation to the pre-culture, increasing editing frequencies from 10% to 66% after pre-selection. Probing the essential polyamine biosynthesis pathway, the spermidine synthase gene (SPD1) is shown to be a potent selectable marker with versatile biotechnological applicability. Very low levels of spermidine (0.75 mg/L) were required to maintain normal mixotrophic and phototrophic growth in newly designed spermidine auxotrophic strains. Complementation of these strains with a synthetic SPD1 gene was achieved when the mature protein was targeted to either the cytosol or the chloroplast. This work highlights the potential of new selectable markers for biotechnology as well as basic research and proposes an effective pipeline for the identification of new auxotrophies in C. reinhardtii.
Subject: Medicine & Pharmacology, Gastroenterology Keywords: CRISPR/Cas9; celiac disease; wheat; sgRNA; gluten; low-immunogenic wheat
Online: 29 September 2021 (15:39:12 CEST)
Wheat gluten contains epitopes that trigger celiac disease (CD). A life-long strict gluten-free diet is the only treatment accepted for CD. However, very low-gluten wheat may provide an alternative treatment to CD. Conventional plant breeding methods are not sufficient to produce celiac-safe wheat. RNA interference technology, to some extent, succeeded in the development of safer wheat varieties. However, these varieties had multiple challenges in their implementation. Clustered Regularly Interspaced Short Palindromic Repeats-associated nuclease 9 (CRISPR/Cas9) is a versatile gene-editing tool that has the ability to edit the immunogenic gluten genes. So far, only a few studies have applied CRISPR/Cas9 to modify the wheat genome. In this article, we reviewed published literature that applied CRISPR/Cas9 in wheat genome editing to investigate the current status of the CRISPR/Cas9 system to produce a low-immunogenic wheat variety. We found that in recent years, the CRISPR/Cas9 system has been continuously improved to edit the complex hexaploid wheat genome. Although some reduced immunogenic wheat varieties have been reported, CRISPR/Cas9 has still not been fully explored in editing the wheat genome. We conclude that further studies are required to apply the CRISPR/Cas9 gene-editing system efficiently for the development of celiac-safe wheat variety and to establish it as a “tool to celiac safe wheat.”
Subject: Life Sciences, Biochemistry Keywords: Mollusc; selective breeding; gene editing; disease resistance; transgenesis; CRISPR/Cas9
Online: 15 October 2020 (16:06:27 CEST)
Molluscan aquaculture is a major contributor to global seafood production, but is hampered by infectious disease outbreaks which can cause serious economic losses. Selective breeding has been widely used to improve disease resistance in major agricultural and aquaculture species, and has clear potential in molluscs, albeit its commercial application remains at a formative stage. Advances in genomic technologies, especially development of cost-efficient genomic selection, have potential to accelerate genetic improvement. However, tailored approaches are required due to the distinctive reproductive and lifecycle characteristics of molluscan species. Transgenesis and genome editing, in particular CRISPR/Cas systems, have been successfully trialled in molluscs, and may further understanding and improvement of genetic resistance to disease through targeted changes to the host genome. Whole organism genome editing is achievable on a much greater scale compared to other farmed species, making genome-wide CRISPR screening approaches plausible. This review discusses the current state and future potential of selective breeding, genomic tools, and genome editing approaches to understand and improve host resistance to infectious disease in molluscs.
REVIEW | doi:10.20944/preprints202007.0578.v1
Subject: Biology, Plant Sciences Keywords: CRISPR; CAS9; CAS12a; NHEJ; Base editing; PAM; Temperature Sensitivity; Agriculture
Online: 24 July 2020 (11:43:03 CEST)
Global population is predicted to approach 10 billion by 2050, an increase of over 2 billion from today. To meet the demands of growing, geographically and socio-economically diversified nations, we need to diversity and expand agricultural production. This expansion of agricultural productivity will need to occur under increasing biotic, and environmental constraints driven by climate change. Clustered regularly interspaced short palindromic repeats-site directed nucleases (CRISPR-SDN) and similar genome editing technologies will likely be key enablers to meet future agricultural needs. While the application of CRISPR-Cas9 mediated genome editing has led the way, the use of CRISPR-Cas12a is also increasing significantly for genome engineering of plants. The popularity of the CRISPR-Cas12a, the type V (class-II) system, is gaining momentum because of its versatility and simplified features. These include the use of a small guide RNA devoid of trans-activating crispr RNA (tracrRNA), targeting of T-rich regions of the genome where Cas9 is not suitable for use, RNA processing capability facilitating simpler multiplexing, and its ability to generate double strand breaks (DSB) with staggered ends. Many monocot and dicot species have been successfully edited using this Cas12a system and further research is ongoing to improve its efficiency in plants, including improving the temperature stability of the Cas12a enzyme, identifying new variants of Cas12a or synthetically producing Cas12a with flexible PAM sequences. In this review we provide a comparative survey of CRISPR-Cas12a and Cas9, and provide a perspective on applications of CRISPR-Cas12 in agriculture.
ARTICLE | doi:10.20944/preprints202003.0424.v1
Subject: Life Sciences, Genetics Keywords: primary congenital glaucoma; exome sequencing; GUCA1C; GCAP3; zebrafish; CRISPR/Cas9
Online: 29 March 2020 (06:33:17 CEST)
Primary congenital glaucoma (PCG) is a heterogeneous, inherited, and severe optical neuropathy caused by apoptotic degeneration of the retinal ganglion cell layer. Whole-exome sequencing analysis of one PCG family identified two affected siblings who carried a low-frequency homozygous nonsense GUCA1C variant (c.52G>T/p.Glu18Ter/rs143174402). This gene encodes GCAP3, a member of the guanylate cyclase activating protein family, involved in phototransduction and with a potential role in intraocular pressure regulation. Segregation analysis supported the notion that the variant was coinherited with the disease in an autosomal recessive fashion. GCAP3 was detected immunohistochemically in the adult human ocular ciliary epithelium and retina. To evaluate the ocular effect of GUCA1C loss-of-function, a guca1c knockout zebrafish line was generated by CRISPR/Cas9 genome editing. Immunohistochemistry demonstrated the presence of GCAP3 in the non-pigmented ciliary epithelium and retina of adult wild-type fishes. Knockout animals presented up-regulation of the glial fibrillary acidic protein in Müller cells and evidence of retinal ganglion cell apoptosis, indicating the existence of gliosis and glaucoma-like retinal damage. In summary, our data provide evidence for the role of GUCA1C as a candidate gene in PCG and offer new insights into the function of this gene in the ocular anterior segment and the retina.
ARTICLE | doi:10.20944/preprints201811.0159.v1
Subject: Biology, Entomology Keywords: Bombyx mori; BmNPV; antiviral therapeutic; CRISPR/Cas9; multi-gene editing
Online: 7 November 2018 (10:23:52 CET)
Clustered regularly interspaced short palindromic repeats/associated protein 9 nuclease (CRISPR/Cas9) technology guided by a single-guide RNA (sgRNA) has recently opened a new avenue for antiviral therapy. A unique capability of the CRISPR/Cas9 system is multiple genome engineering. However, there are few applications in insect viruses by a single Cas9 enzyme targeting two or more sgRNA at different genomic sites for simultaneous production of multiple DNA breaks. To address the need for multi-gene editing and sustained delivery of multiplex CRISPR/Cas9-based genome engineering tools, we developed a one-vector (pSL1180-Cas9-U6-sgRNA) system to express multiple sgRNA and Cas9 protein to excise Bombyx mori nucleopolyhedrovirus (BmNPV) in insect cells. Here, ie-1, gp64, lef-11, and dnapol genes were screened and identified as multiple sgRNA editing sites according to the BmNPV system infection and DNA replication mechanism. Furthermore, we constructed a multiplex editing vector sgMultiple to efficiently regulate multiplex gene editing steps and inhibit BmNPV replication after viral infection. This is the first report that describes the application of multiplex CRISPR/Cas9 system inhibiting insect virus replication. This multiplex system can significant enable the potential of CRISPR/Cas9-based multiplex genome engineering in transgenic silkworms.
REVIEW | doi:10.20944/preprints202107.0182.v1
Subject: Life Sciences, Biochemistry Keywords: CRISPR-Cas9; Genome editing; plant editing; bacterial immune system; genetic disease
Online: 8 July 2021 (09:50:22 CEST)
Clustered regularly interspaced short palindromic repeats or CRISPR, one of the major technological tools from nature's toolbox, has revolutionized the scientific world with its potential use in humans and plants. CRISPR Cas9 was first known as an adaptive immune system of bacteria. It is a system that cleaves foreign DNA. It has been exploited to be used as a genome editing tool for correcting genetic diseases in humans, for plants to create stress-resistant plants, and for a variety of different purposes. This review provides a basic overview of its applications in different areas of biological research. It has immense potential for a variety of researches, but it's still a mystery for science. It feels like scientists just know a tip of an iceberg.
ARTICLE | doi:10.20944/preprints202105.0142.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Cancer Immunotherapy; Cancer Vaccine; Cancer Antigens; CRISPR-Cas9; Engineered T Cells.
Online: 7 May 2021 (11:10:13 CEST)
The mechanisms involved in immune responses to cancer have been extensively studied for several decades and, considerable attention has been paid to harnessing the immune system's therapeutic potential. Cancer immunotherapy has established itself as a promising new treatment option for a variety of cancer types. Various strategies including cancer vaccines, monoclonal antibodies (mAbs), adoptive T-cell-cancer therapy and immune test therapy have gained prominence through immunotherapy. However, it remains to be accomplished the full potential of cancer immunotherapy. In spite of having startling aspects, the cancer immunotherapies have some difficulties including the inability to effectively targeting the cancer antigens and the abnormalities in patient response. With the advancement of technology, this system has changed the genome-based immunotherapy process in the human body including generation of engineered T cells. Due to its high specificity, CRISPR-Cas9 has become a simple and flexible genome-editing tool to target nearly any genomic locus. Recently, the CD19-mediated CAR-T cell (chimeric antigen receptor T cell) therapy has opened a new avenue for the treatment of human cancer, though low efficiency is a major drawback of this process. Thus, increasing the efficiency of the CAR-T cell (engineered T cells that induce the chimeric antigen receptor) by using CRISPR-Cas9 technology could be a better weapon to fight against the cancer. In this review, we have broadly focused on the use of CRISPR-Cas9 technology for the modification of the T-cell, which can specifically recognize cancer cells and be used as immune therapeutics against cancer. We have also demonstrated the other potential strategies for the treatment of cancer.
ARTICLE | doi:10.20944/preprints202011.0723.v1
Subject: Life Sciences, Biochemistry Keywords: Fanconi anemia; gene editing; FANCA; head and neck cancer; CRISPR/Cas9
Online: 30 November 2020 (11:55:45 CET)
Fanconi anemia (FA) patients have an exacerbated risk of head and neck squamous cell carcinoma (HNSCC). Treatment is challenging as FA patients display enhanced toxicity to standard treatments, including radio/chemotherapy. Therefore better therapies as well as new disease models are urgently needed. We have used CRISPR/Cas9 editing tools in order to interrupt the human FANCA gene by the generation of insertions/deletions (indels) in exon 4 in two cancer cell lines from sporadic HNSCC having no mutation in FA-genes: CAL27 and CAL33 cells. Our approach allowed efficient editing, subsequent purification of single-cell clones, and Sanger sequencing validation at the edited locus. Clones having frameshift indels in homozygosis did not express FANCA protein and were selected for further analysis. When compared with parental CAL27 and CAL33, FANCA-mutant cell clones displayed a FA-phenotype as they i) are highly sensitive to DNA interstrand crosslink (ICL) agents such as mitomycin C (MMC) or cisplatin, ii) do not monoubiquitinate FANCD2 upon MMC treatment and therefore iii) do not form FANCD2 nuclear foci, and iv) they display increased chromosome fragility and G2 arrest after diepoxybutane (DEB) treatment. These FANCA-mutant clones display similar growth rates as their parental cells. Interestingly, mutant cells acquire phenotypes associated with more aggressive disease, such as increased migration in wound healing assays. Therefore, CAL27 and CAL33 cells with FANCA mutations are phenocopies of FA-HNSCC cells.
ARTICLE | doi:10.20944/preprints202005.0134.v1
Subject: Life Sciences, Molecular Biology Keywords: Crispr-Cas9; ACE2 gene; SARS-CoV-2; new coronavirus; COVID-19
Online: 7 May 2020 (15:26:06 CEST)
The human angiotensin-converting enzyme 2 (ACE2) has a crucial role on blood pressure control; however, ACE2 is also the primary SARS-CoV-2 (S domain) virus receptor. Inhibiting or even reducing the expression of the native ACE2 might diminish the viral entry into the cells, but may cause a failure of ACE2 biological activity, primarily in patients with comorbidities, including diabetes mellitus or hypertension. Since the ACE2 catalytic site and the SARS-Cov-2 receptor are distinct, we designed a Crispr-Cas9 model system, predicting the respective sequences for a guide RNA (gRNA) and a single-stranded oligo dideoxy nucleotide (ssODN), to introduce point mutations into the exon 1 of the human ACE2 gene, which encodes the alpha-helix, implicated on the binding of the SARS-CoV-2 envelope S protein. Protein modeling predicted that the specific substitutions of residues Phe28, Lys31, and Tyr41 for Ala at the ACE2 alpha-helix do not significantly alter ACE2 native conformation. The analysis of the impact of these mutations on ACE2 receptor function predicted a weakening of the binding of the SARS-CoV-2 protein S. An experimental genome editing of cells based on these Crispr-Cas9 elements might reduce the SARS-CoV-2 ability to enter the epithelial cell, preserving the biological activity of ACE2 enzyme.
REVIEW | doi:10.20944/preprints201710.0065.v1
Subject: Life Sciences, Genetics Keywords: hepatitis B virus; chronic hepatitis B; cccDNA; CRISPR/Cas9; gene therapy
Online: 10 October 2017 (17:59:11 CEST)
BACKGROUND: Chronic hepatitis B infected with Hepatitis B virus remains a major health concern worldwide. Despite standard interferon-α and nucleotide analogues have been shown to reduce the deterioration of liver disease among chronic hepatitis B patients, covalently closed circular DNA was still difficult to eradicate. METHODS: A literature search of Pubmed and Web of science was performed with the following key words: ‘CRISPR’, ‘CRISPR/Cas9’, ‘hepatitis B’, ‘HBV’, ‘chronic hepatitis B’ and ‘HBV cccDNA’. The information about CRISPR/Cas9 for the treatment of HBV cccDNA or hepatitis B was reviewed. RESULTS: CRISPR/Cas9 could treat hepatitis B through suppressing or clearing HBV cccDNA with different gRNAs. CONCLUSION: With the emergence of CRISPR/Cas9 (the RNA-guided clustered regulatory interspaced short palindromic repeats, CRISPR) editing technology, clearance of hepatitis B virus and better prevention of liver carcinoma seemed to be possible.
REVIEW | doi:10.20944/preprints202212.0529.v1
Subject: Life Sciences, Biotechnology Keywords: CRISPR; Cas9 ribonucleoprotein; virus-like particles; exosomes; HIV assembly and disassembly; delivery
Online: 28 December 2022 (06:11:59 CET)
Rapid progress in gene editing based on clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) has revolutionized the study of gene and genome function and genetic disease correction. While numerous genetically modified cellular and animal models have been created to understand biological processes, the clinical application of CRISPR/Cas tools has been impeded by off-targeting and delivery problems. It is generally accepted that the delivery of CRISPR in the form of a ribonucleoprotein complex (RNP) substantially reduces the time of DNA exposure to the effector nuclease, minimizing off-target effects and facilitating clinical usage. This review focuses on CRISPR/Cas RNP delivery with retro/lentiviral particles and exosomes, whose parallel production by cells transfected with viral vectors is underestimated. We critically evaluate specific mechanisms of extracellular particle formation and loading with CRISPR/Cas for each system. Additionally, the details of Cas-nanoparticle entry and uncoating, previously unappreciated in the context of gene editing efficiency, are discussed. Based on existing knowledge about the consequences of intervention in retroviral assembly, entry, or exosome formation, we outline the potential problems with CRISPR/Cas delivery using extracellular nanoparticles and ways to address them.
REVIEW | doi:10.20944/preprints202103.0277.v1
Subject: Biology, Anatomy & Morphology Keywords: CRISPR/Cas9; Disease resistance; Future perspective; Improvement of plants; Molecular scissor; Revolution
Online: 10 March 2021 (11:10:58 CET)
The growing population meet the challenge for agricultural production. CRISPR/Cas9 technology is based on plant research for the development of the new varieties as well as disease resistance crops. In addition the deletion of significant characters makes the new alleles from the CRISPR/Cas9. Recent and reliable molecular scissor for genetic engineering. The review is focused on the various application of the CRISPR/Cas9 technology in plant enhancement of plant disease resistance, stress burden in plant, nutritional improvement, and quality of crops from the CRISPR/Cas9 system. The clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein9 (cas9) is adopted from the prokaryotic type II system. CRISPR/Cas9 is simplicity and efficiency than ZENs and TALENs for the genome engineering. Due to rapid growing of the CRISPR/Cas9 system has been formulate the adaptation of many plant species. The current advancement of plants and future schemes of improve of CRISPR technology has been presented in contest of multiplex editing, knowledge on induced mutation whether the factor effect in CRISPR/Cas9 technology in plant. Remarkable perspective and challenges of CRISPR/Cas9 technology in significance of plant genetic modification.
ARTICLE | doi:10.20944/preprints202008.0619.v1
Subject: Biology, Plant Sciences Keywords: CRISPR-Cas9; course-based undergraduate research experience; CURE; remote learning; plant biology
Online: 27 August 2020 (12:29:53 CEST)
Gene editing tools such as CRISPR-Cas9 have created unprecedented opportunities for genetic studies in plants and animals. We designed a course-based undergraduate research experience (CURE) to train introductory biology students in the concepts and implementation of gene editing technology as well as develop their soft skills in data management and scientific communication. We present two versions of the course that can be implemented with twice-weekly meetings over a five-week period. In the remote-learning version, students perform homology searches, design guide RNAs and primers, and learn the principles of molecular cloning. This version is appropriate when access to laboratory equipment or in-person instruction is limited, such as closures that have occurred in response to the Covid-19 pandemic. In the in-person version, students design guide RNAs, clone CRISPR-Cas9 constructs, and perform genetic transformation of the model plant Arabidopsis thaliana. The highly parallel nature of the CURE makes it possible to target dozens to hundreds of genes, depending on the number of course sections available. Applying this approach in a sensitized mutant background enables focused reverse genetic screens for genetic suppressors or enhancers. The course can be readily adapted to other organisms or projects that employ gene editing.
REVIEW | doi:10.20944/preprints202209.0117.v1
Subject: Life Sciences, Biotechnology Keywords: abiotic stress tolerance; base editing; CRISPR/Cas9; crop production; gene editing; prime editing
Online: 8 September 2022 (03:31:39 CEST)
Abiotic stresses, including drought, salinity, cold, heat, and heavy metals, extensively reduce global agricultural production. Approaches such as conventional breeding and transgenic breeding have been widely used to cope with these environmental stresses. The clustered regularly interspaced short palindromic repeat- Cas (CRISPR/Cas) based gene-editing tool has revolutionized due to its simplicity, accessibility, adaptability, flexibility, and wide applicability. This system has a great potential to build up crop varieties with enhanced tolerance against abiotic stresses. In this review, we summarize the most recent findings on understanding the mechanism of abiotic stress response in plants and the application of CRISPR/Cas mediated gene-editing system towards enhanced tolerance to drought, salinity, cold, heat, and heavy metals stresses. Furthermore, in this review, we highlighted the recent advancements in prime editing and base editing tools for crop improvement.
REVIEW | doi:10.20944/preprints202201.0137.v1
Subject: Life Sciences, Immunology Keywords: Adoptive T cell therapy; CAR T cells; CRISPR/Cas9; gene modifications; T cells
Online: 11 January 2022 (12:57:40 CET)
Adaptive T cell immunotherapy holds great promise for the successful treatment of leukemia as well as other types of cancers. More recently, it was also shown to be an effective treatment option for chronic virus infections in immunosuppressed patients. Autologous or allogeneic T cells used for immunotherapy are usually genetically modified to express novel T cell or chimeric antigen receptors. The production of such cells was significantly simplified with the CRISPR/Cas system allowing deletion or insertion of novel genes at specific locations within the genome. In this review, we describe recent methodological breakthroughs important for the conduction of these genetic modifications, summarize crucial points to be considered when conducting such experiments, and highlight the potential pitfalls of these approaches.
ARTICLE | doi:10.20944/preprints202104.0474.v1
Subject: Life Sciences, Biochemistry Keywords: CRISPR/Cas9; knockout; rescue; desiccation tolerance; anhydrobiosis; Polypedilum vanderplanki; HSF1; insect cell; Pv11
Online: 19 April 2021 (12:17:34 CEST)
Pv11, an insect cell line established from the midge Polypedilum vanderplanki, is capable of ametabolic desiccation tolerance, so-called anhydrobiosis. We previously discovered that heat shock factor 1 (HSF1) contributes to the acquisition of desiccation tolerance by Pv11 cells, but the mechanistic details have yet to be elucidated. Here, by analyzing the gene expression profiles of newly established HSF1-knockout and -rescue cell lines, we show that HSF1 has a genome-wide effect on gene regulation in Pv11. HSF1-knockout cells exhibit a reduced desiccation survival rate, but this is completely restored in HSF1-rescue cells. By comparing mRNA profiles of the two cell lines, we reveal that HSF1 induces anhydrobiosis-related genes, especially genes encoding late embryogenesis abundant proteins and thioredoxins, but represses a group of genes involved in basal cellular processes, thus promoting an ametabolic state in the cell. In addition, HSF1 binding motifs are enriched in the promoters of anhydrobiosis-related genes and we demonstrate binding of HSF1 to these promoters by ChIP-qPCR. Thus, HSF1 directly regulates the transcription of anhydrobiosis-related genes and consequently plays a pivotal role in the induction of anhydrobiotic ability in Pv11 cells.
ARTICLE | doi:10.20944/preprints202010.0102.v1
Subject: Life Sciences, Biochemistry Keywords: lncRNA; LINC00961; SPAAR; scRNASeq; CRISPR/Cas9; cardiovascular physiology; fetal growth restriction; myocardial infarction
Online: 5 October 2020 (17:47:46 CEST)
Long non-coding RNAs (lncRNAs) have structural and functional roles in development and disease. We have previously shown that the LINC00961/SPAAR locus regulates endothelial cell function, and that both the lncRNA and micropeptide counter-regulate angiogenesis. To assess human cardiac cell SPAAR expression we mined a publicly available scRNSeq dataset and confirmed LINC00961 locus expression and hypoxic response in a murine endothelial cell line. We investigated post-natal growth and development, basal cardiac function, the cardiac functional response and tissue-specific response to myocardial infarction. To investigate the contribution of the LINC00961/SPAAR locus to determination of longitudinal growth, cardiac function, and response to myocardial infarction, we used a novel CRISPR/Cas9 locus knockout mouse line. Data mining suggested that SPAAR is predominantly expressed in human cardiac endothelial cells and fibroblasts, while murine LINC00961 expression is hypoxia-responsive in mouse endothelial cells. LINC00961-/- mice displayed a sex-specific delay in longitudinal growth and development, smaller left ventricular systolic and diastolic areas and volumes, and greater risk area following myocardial infarction compared with wildtype littermates. These data suggest a role for the LINC00961/SPAAR locus in cardiac endothelial cell and fibroblast cell function and hypoxic-response, and in growth and development, and basal cardiovascular function in adulthood.
REVIEW | doi:10.20944/preprints202009.0490.v1
Subject: Biology, Other Keywords: base editing; prime editing; ABE; SCD; sickle cell disease; sickle cell anemia; CRISPR; Cas9
Online: 21 September 2020 (04:23:21 CEST)
Sickle cell disease is characterized by stiff, “sickled” red blood cells that have difficulty moving through the bloodstream and do not efficiently carry oxygen. It is an inherited disease with severely limited treatment options, and is caused by a point mutation. Its prevalence in black and brown communities makes the already limited treatment options even less accessible. Base editing and prime editing are two relatively recent discoveries in the field of genome editing and were developed after the groundbreaking discovery of the CRISPR Cas9 system. While not fully tested, they hold a lot of promise in providing alternative treatment options for sickle cell disease. Both editing systems are able to install individual point mutations in the beta globin gene, which is where the sickle cell mutation occurs, and can thus cure sickle cell disease (in theory). In this paper we outline the mechanisms of CRISPR-Cas9 systems and base and prime editing, and provide insight into how to apply them to treat SCD. Further investigation should be done on specific editing systems and designs to use to ensure optimal treatment of SCD.
ARTICLE | doi:10.20944/preprints201810.0451.v1
Subject: Life Sciences, Molecular Biology Keywords: CTCF; tumour suppressor gene; haploinsufficiency; zinc finger; CRISPR/Cas9; cancer; endometrial cancer; gene editing
Online: 19 October 2018 (11:29:01 CEST)
CCCTC-binding factor (CTCF) is a conserved transcription factor that performs diverse roles in transcriptional regulation and chromatin architecture. Cancer genome sequencing reveals diverse acquired mutations in CTCF, which we have shown, functions as a tumour suppressor gene. While CTCF is essential for embryonic development, little is known of its absolute requirement in somatic cells and the consequences of CTCF haploinsufficiency. We examined the consequences of CTCF depletion in immortalised human and mouse cells using shRNA knockdown and CRISPR/Cas9 genome editing and examined the growth and development of heterozygous Ctcf (Ctcf+/-) mice. We also analysed the impact of CTCF haploinsufficiency by examining gene expression changes in CTCF-altered endometrial carcinoma. Knockdown and CRISPR/Cas9-mediated editing of CTCF reduced the cellular growth and colony-forming ability of K562 cells. CTCF knockdown also induced cell cycle arrest and a pro-survival response to apoptotic insult. However, in p53 shRNA-immortalised Ctcf+/- MEFs we observed the opposite: increased cellular proliferation, colony formation, cell cycle progression and decreased survival after apoptotic insult compared to wild type MEFs. CRISPR/Cas9-mediated targeting in Ctcf+/- MEFs revealed a predominance of in-frame microdeletions in Ctcf in surviving clones, however protein expression could not be ablated. Examination of CTCF mutations in endometrial cancers showed locus-specific alterations in gene expression due to CTCF haploinsufficiency, in concert with downregulation of tumour suppressor genes and upregulation of estrogen-responsive genes. Depletion of CTCF expression imparts a dramatic negative effect on normal cell function. However, CTCF haploinsufficiency can have growth-promoting effects consistent with known cancer hallmarks in the presence of additional genetic hits. Our results confirm the absolute requirement for CTCF expression in somatic cells and provide definitive evidence of CTCF’s role as a haploinsufficient tumour suppressor gene. CTCF genetic alterations in endometrial cancer indicate that gene dysregulation is a likely consequence of CTCF loss, contributing to, but not solely driving cancer growth.
ARTICLE | doi:10.20944/preprints202212.0442.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: P21; CDKN1A; glioblastoma; senescence; cancer senescence; gene overexpression; gene knock-in; CRISPR/Cas9; dCas; dCas-VPR
Online: 23 December 2022 (04:10:22 CET)
High-grade gliomas are the most common and aggressive adult primary brain tumors with a median survival of only 12-15 months. Current standard therapy consists of maximal safe surgical resection followed by DNA-damaging agents, such as irradiation and chemotherapy that can delay but not prevent inevitable recurrence. Some have interpreted glioma recurrence as evidence of glioma stem cells which persist in a relatively quiescent state after irradiation and chemotherapy, before the ultimate cell cycle re-entry and glioma recurrence. Conversely, latent cancer cells with a therapy-induced senescent phenotype have been shown to escape senescence, giving rise to more aggressive stem-like tumor cells than those present in the original tumor. Therefore, approaches are needed to either eliminate or keep these glioma-initiating cells in a senescent state for a longer time to prolong survival. In our current study, we demonstrate that the radiation-induced cell cycle inhibitor P21 can provide a powerful route to induce cell death in short-term explants of PDXs derived from three molecularly diverse human gliomas. Additionally, cells not killed by P21 overexpression were maintained in a stable senescent state for longer than control cells. Collectively, these data suggest that P21 activation may provide an attractive therapeutic target to improve therapeutic outcomes.
Subject: Life Sciences, Biochemistry Keywords: synthetic biology; CRISPR; Cas9; biotechnology; biodesign; nickase; base editing; prime editing; genome editing; ethics; responsible innovation
Online: 1 October 2020 (08:38:22 CEST)
The RNA-guided endonuclease system CRISPR-Cas9 has been extensively modified since its discovery, allowing its capabilities to be extending far beyond double-stranded cleavage to high fidelity insertions, deletions, and single base edits. Such innovations have been possible due to the modular architecture of CRISPR-Cas9 and the robustness of its component parts to modifications and the fusion of new functional elements. Here, we review the broad toolkit of CRISPR-Cas9-based systems now available for diverse genome editing tasks. We provide an overview of their core molecular structure and mechanism and distil the design principles used to engineer their diverse functionalities. We end by looking beyond the biochemistry and towards the societal and ethical challenges that these CRISPR-Cas9 systems face if their transformative capabilities are to be deployed in a safe and acceptable manner.
ARTICLE | doi:10.20944/preprints202106.0169.v1
Subject: Life Sciences, Biochemistry Keywords: melanoma initiating cells; CD133; drug resistance; apoptosis; caspase activation; CRISPR-Cas9 knockout; AKT; BAD; BCL-2 family
Online: 7 June 2021 (12:11:10 CEST)
Malignant melanoma is a lethal skin cancer containing melanoma-initiating cells (MIC), implicated in tumorigenesis, invasion, and drug resistance, and characterized by elevated expression of stem cell markers, such as CD133. We previously showed that siRNA knockdown of CD133 enhances apoptosis induced by the MEK inhibitor trametinib in melanoma cells. The current study investigates underlying mechanisms of CD133’s anti-apoptotic activity in patient-derived BAKP and POT cells, harboring difficult-to-treat NRASQ61K and NRASQ61R drivers, after CRISPR-Cas9 CD133 knockdown or Dox-inducible expression of CD133. To maintain stable expression of CD133, MACS-sorted CD133(+) positive cells were expanded by ROCK-mediated conditional reprogramming of BAKP melanoma cells (BAKR). BAKR showed increased survival via reduced apoptosis after exposure to trametinib or DTIC, compared to BAKP. CRISPR-Cas9- mediated CD133 knockdown in BAKR cells (BAKR-T3) re-sensitized the cells, while CRISPR-Cas9 knockdown of CD133 in parental BAKP and POT cells even further increased trametinib-induced apoptosis (cleaved PARP) by reducing levels of anti-apoptotic BCL-xL, p-AKT, and p-BAD, and increasing pro-apoptotic BAD and active BAX. Dox-induced CD133 overexpression had the opposite effect, and blocked trametinib-induced apoptosis in both cell lines, coincident with elevated p-AKT, p-BAD, BCL-2 and BCL-xL and decreased levels of the active form of BAX and caspases-3 and -9. The roles of CD133 in AKT and BAD phosphorylation, or in the upregulation of anti-apoptotic BCL-2 family members, was further investigated by AKT knockout with siRNA, or inhibition of BCL-2 family members with navitoclax (ABT-263). Similar to CD133 knockdown, AKT1/2 siRNA knockdown in BAKP cells also reduced p-BAD. CD133 knockdown (T3)-mediated reduction of pBAD levels was equivalent in AKT-knockdown or AKT control cells indicating that CD133 may be upstream of AKT signaling. In BAKP cells treated with trametinib and/or ABT-263, effects of ABT-263 mirrored CD133 knockdown, since levels of active BAX and cleaved-PARP in BAKP-SC (CD133-) cells increased to the same level as that exhibited by BAKP-T3 cells (CD133+). CD133 may therefore activate a survival pathway where 1) increased phosphorylation of AKT induces 2) phosphorylation and inactivation of BAD, 3) decrease in the active form of BAX, and 4) reduction in caspase-mediated PARP cleavage, indicating apoptosis suppression leading to drug resistance in melanomas. Targeting survival pathways by which CD133 may confer chemoresistance in MICs can contribute to development of more effective treatments for patients with high-risk melanoma.
REVIEW | doi:10.20944/preprints201810.0010.v1
Subject: Medicine & Pharmacology, Ophthalmology Keywords: Gene therapy, gene editing, CRISPR/Cas9, Cas12a, dual AAV, triple AAV, clinical trials, retina, hereditary retinal dystrophies
Online: 1 October 2018 (13:52:23 CEST)
Recently, there have been revolutions in the development of both gene therapy and genome surgical treatments for inherited diseases. Much of this progress has been centered around hereditary retinal dystrophies, because the eye is an immune-privileged and anatomically ideal target. Gene therapy treatments, already demonstrated to be safe and efficacious in numerous clinical trials, are benefitting from the development of new viral vectors, such as dual and triple AAVs. CRISPR/Ca9, which revolutionized the field of gene editing, is being adapted into more precise “high fidelity” and catalytically dead variants. New CRISPR endonucleases, such as CjCas9 and Cas12a, are generating excitement in the field as well. Stem cell therapy has emerged as a promising alternative, allowing human embryo derived stem cells and induced pluripotent stem cells to be edited precisely in vitro and then reintroduced into the body. This article highlights recent progress made in gene therapy and genome surgery for retinal disorders, and it provides an update on precision medicine FDA treatment trials.
REVIEW | doi:10.20944/preprints201907.0211.v2
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: HIV-1; CRISPR-Cas9; T-cells; lipid nanoparticles; gut-associated-lymphoid tissue; Co-receptors; Probiotics; GI Tract,; Gene Editing
Online: 13 April 2020 (10:57:52 CEST)
HIV-1 is a complicated and perplexing virus. It infects T cells, reverse transcribes its RNA into DNA, utilizes its host DNA machinery to replicate its HIV-DNA, translates the HIV-DNA into proteins, assembles itself for a budding escape from the T cell, and rapidly mutates its conformation. Partially, due to its complexity, there remains no cure for HIV or AIDs. However, recently with the discovery of TALENs, the use of zinc fingers, and most of all the applications of CRISPR-Cas9 technology, has given researchers new hope in finding alternative gene therapies and treatments for diseases. With more focus on CRISPR-Cas9, this new and novel technology uses a guiding RNA, sgRNA, to lead a Cas9 nuclease to its target for deletion or to change that DNA site. CRISPR-Cas9 can delete point mutations and multiple DNA sites. Because CRISPR can alter DNA sequences, several scientists have conducted research into CRISPR, possibly treating more diseases such as cancer, diabetes, and even HIV. HIV-1 drew the focus of a researcher named Dr. Ebina in 2013 when he was the first to design and apply CRISPR-Cas9 to genes found in the binding sites of HIV-1, inhibiting HIV-1 gene expression. Since 2013, several other researchers have blocked HIV replication and infection through CRISPR-Cas9 targeting the receptors of T cells called the CC chemokine receptor 5 or CCR5. HIV-1 binds to the CD4 receptor of T cells, which consists of co-receptors CCR5 and CXCR4. If CCR5 expression can be removed, the HIV virus cannot bind to T-cells, blocking the initial attachment stage, and discontinuing the infection. However, there remain obstacles and issues for the CRISPR deletion of CCR5 for treating HIV-1. The issues include: 1) finding new and safe methods of CRISPR-Cas9 delivery, 2) clearing the latent HIV reservoirs, 3) improving the sgRNA design to avoid off-target mutations or deletions, and 4) effectively analyze the viral escape of HIV from CRISPR-Cas9 modifications. Therefore, the purpose of this review is to discuss possible techniques for removing the obstacles that can lessen the potential of CRISPR to delete CCR5, repressing HIV-1 into long-term remission or a functional cure.
REVIEW | doi:10.20944/preprints202006.0025.v1
Online: 4 June 2020 (06:03:16 CEST)
COVID-19 represents an unprecedented threat to global public health and economies. Assays are urgently needed for rapid detection and diagnosis of SARS-CoV-2-infected patients in order to inform treatment and quarantine strategies. Establishing globally accepted easy-to-access diagnostic tests is extremely important to understanding the epidemiology of the present pandemic. While nucleic acid-based tests are considered to be more sensitive with respect to serological tests, but the present gold standard RT-PCR-based assays possess limitations such as low sample throughput, requirement for sophisticated reagents and instrumentation. To overcome these shortcomings, recent efforts of incorporating LAMP-based isothermal detection, and minimizing the number of reagents required are on rise. Novel CRISPR- and other nuclease-based techniques, when merge with isothermal and allied technologies, promises to provide sensitive and rapid detection of SARS-CoV-2 nucleic acids. Here we discuss and present compilation of state-of-the-art CRISPR based detection techniques for use in COVID diagnosis and epidemiology.
ARTICLE | doi:10.20944/preprints202205.0008.v1
Subject: Life Sciences, Molecular Biology Keywords: Chronic Myeloid Leukaemia; BCR/ABL; CRISPR; Gene therapy; CRISPR-Trap.
Online: 4 May 2022 (12:30:11 CEST)
Chronic myeloid leukaemia (CML) is a haematological neoplasm driven by the BCR/ABL fusion oncogene. The monogenic aspect of the disease and the feasibility of ex vivo therapies in haematological disorders make CML an excellent candidate for gene therapy strategies. The ability to abolish any coding sequence by CRISPR-Cas9 nucleases offers a powerful therapeutic opportunity to CML patients. However, a definitive cure can only be achieved when only CRISPR-edited cells are selected. A gene-trapping approach combined with CRISPR technology would be an ideal approach to ensure this. Here, we have developed a CRISPR-Trap strategy that efficiently inserts a donor gene trap (SA-CMV-Venus) cassette into the BCR-ABL1-specific fusion point in the CML K562 human cell line. The trapping cassette interrupts the on-cogene coding sequence and expresses a reporter gene that enables the selection of edited cells. Quantitative expression analyses showed significantly higher level of expression of the BCR-Venus allele coupled with a drastically lower level of BCR/ABL expression in Venus+ cell fractions. Functional in vitro experiments showed cell proliferation arrest and apoptosis in selected Venus+ cells. Finally, xenograft experiments with the selected Venus+ cells showed a large reduction in tumour growth, thereby demonstrating a therapeutic benefit in vivo. This study is a proof of concept for the therapeutic potential of a CRISPR-Trap system as a novel strategy for gene elimination in haematological neoplasms.
REVIEW | doi:10.20944/preprints202211.0318.v1
Subject: Life Sciences, Molecular Biology Keywords: Genome editing 4; C. elegans 5; Genome engineering; CRISPR; CRISPR-Cas
Online: 17 November 2022 (02:22:43 CET)
CRISPR-Cas allows us to introduce desired genome editing, including mutations, epitopes, and deletions with unprecedented efficiency. The development of CRISPR-Cas has progressed to such an extent that it is now applicable in various fields with the help of model organisms. C. elegans is one of the pioneering animals in which numerous CRISPR-Cas strategies have been rapidly es-tablished over the past decade. Ironically, the emergence of numerous methods makes the right choice of method difficult. Choosing an appropriate selection or screening approach is the first step in planning a genome modification. This report summarizes the key features and applications of CRISPR-Cas methods using C. elegans and illustrates key strategies. Our overview of significant advances in CRISPR-Cas will help readers to understand current advances in genome editing and navigate various methods of CRISPR-Cas genome editing.
REVIEW | doi:10.20944/preprints202102.0033.v1
Subject: Biology, Plant Sciences Keywords: CRISPR interference; CRISPR/dCas9 system; crop improvement; gene silencing; RNAi; transcriptional regulation
Online: 1 February 2021 (13:31:04 CET)
RNA-guided genomic transcriptional regulation tools, namely Clustered Regularly Interspaced Short Palindromic Repeats interference (CRISPRi) and CRISPR-mediated gene activation (CRISPRa), are a powerful technology for the field of functional genomics. Deriving from the CRISPR/Cas9 system, both systems comprise a catalytically dead Cas9 (dCas9) and a single guide RNA (sgRNA). This type of dCas9 is incapable of cleaving DNA but retains its ability to specifically bind to DNA. The binding of the dCas9/sgRNA complex to a target gene results in transcriptional interference. The CRISPR/dCas9 system has been explored as a tool for transcriptional modulation and genome imaging. Despite its potential applications and benefits, the challenges and limitations faced by the CRISPR/dCas9 system include the off-target effects, PAM sequence requirement, efficient delivery methods, and the CRISPR/dCas9-interfered crops being labeled as genetically modified organisms in several countries. This review highlights the progression of CRISPR/dCas9 technology as well as its applications and potential challenges in crop improvement.
ARTICLE | doi:10.20944/preprints202005.0001.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: CRISPR-Cas9; high-content screening (HCS); fluorescent-activated cell sorting (FACS); Parkinson's disease (PD); patient-derived iPS; single-cell clones; isogenic cell lines; SNCA; alpha-synuclein; A30P
Online: 2 May 2020 (11:20:20 CEST)
The generation of isogenic induced pluripotent stem cell (iPSC) lines using CRISPR-Cas9 technology is a technically challenging, time-consuming process with variable efficiency. Here we use fluorescence-activated cell sorting (FACS) to sort biallelic CRISPR-Cas9 edited single-cell iPS clones into high-throughput 96-well microtiter plates. We used high-content screening (HCS) technology and generated an in-house developed algorithm to select the correctly edited isogenic clones for continued expansion and validation. In our model we have gene-corrected the iPSCs of a Parkinson’s disease (PD) patient carrying the autosomal dominantly inherited heterozygous c.88G>C mutation in the SNCA gene, which leads to the pathogenic p.A30P form of the alpha-synuclein protein. Undertaking a PCR restriction-digest mediated clonal selection strategy prior to sequencing, we were able to post-sort validate each isogenic clone using a quadruple screening strategy. Subsequent transfection with mRNA encoding excision-only transposase allows for the generation of footprint-free isogenic iPSC lines. These monoclonal isogenic iPSC lines retain a normal molecular genotype, express pluripotency markers and have the ability to differentiate into the three germ layers. This combinatory approach of FACS, HCS and post-sorted restriction digestion facilitates the generation of isogenic cell lines for disease modelling to be scaled-up on an automated platform.
REVIEW | doi:10.20944/preprints202105.0598.v1
Online: 25 May 2021 (09:58:47 CEST)
One of the biggest threats we face globally is the emergence of antimicrobial resistant (AMR) bacteria, which runs in parallel with a lack in the development of new antimicrobials. Among these AMR bacteria, pathogens belonging to the ESKAPE group can be highlighted (Enterococcus spp, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp) due to their profile of drug resistance and virulence. Therefore, innovative lines of treatment must be developed for these bacteria. In this review, we summarize the different strategies for the treatment and study of molecular mechanisms of AMR in the ESKAPE pathogens based on the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated (Cas) proteins' technologies: loss of plasmid or cellular viability, random mutation or gene deletion as well directed mutations that lead to a gene's loss of function.
ARTICLE | doi:10.20944/preprints202004.0232.v1
Online: 15 April 2020 (09:10:49 CEST)
Laminopathies are causally associated with mutations on Lamin A gene (LMNA). To date, more than 400 mutations in LMNA have been reported in patients. These mutations are widely distributed throughout the entire gene and are associated with a wide range of phenotypes. Unfortunately, little is known about the mechanisms underlying the effect of the majority of these mutations. This is the case of more than 40 mutations that are located at exon 4. Using CRISPR/Cas9 technology, we have generated a collection of Lmna exon 4 mutants in mouse C2C12 myoblasts. These cell models include different types of exon 4 deletions and the presence of R249W mutation, one of the human variants associated with a severe type of laminopathy (LMNA-associated congenital muscular dystrophy). We have characterized these clones by measuring their nuclear circularity, myogenic differentiation capacity in 2D and 3D conditions, DNA damage, and p-ERK and p-AKT levels. Our results indicate that Lmna exon 4 mutants show abnormal nuclear morphology. In addition, levels and/or subcellular localization of different members of the lamin and LINC complex are altered in all these mutants. Whereas no significant differences were observed for ERK and AKT activities, the accumulation of DNA damage was associated to the Lmna p.R249W mutant myoblasts. Finally, significant myogenic differentiation defects were detected in the Lmna exon 4 mutants. These results have key implications in the development of future therapeutic strategies for the treatment of laminopathies.
REVIEW | doi:10.20944/preprints201812.0001.v1
Online: 2 December 2018 (10:13:38 CET)
This review summarizes the use of CRISPR system in yeasts, identifying advantages and disadvantages of its applications. 39 articles were evaluated including 12 articles that discussed the advantages of new CRISPR systems that improved the initial system, and another 27 were evaluated, among these: three were applications in Cryptococcus neoformans, four in candida sp., three in Schizosaccharomyces pombe, nine in Saccharomyces cerevisiae, four in Yarrowia lipolytica, and four in industrially important yeasts such as Pichia pastoris and Saccharomyces pastorianus. It was concluded that the CRISPR system is one of the most versatile genetic editing systems available nowadays. It can be applied in different organisms for several effects including gene knock-outs, performing point mutations, gene expression, or even applying multiple edition operations in several genes. However, we recognize that numerous studies lack a control group of the mutated strains, which leaves many questions unanswered. For instance, the extent and precision of this techniques, it also represents a risk to biosecurity standards. Therefore, this review shows the compilation of CRISPR system information, which could be used to generate different alternatives in the industry and clinical fields.
REVIEW | doi:10.20944/preprints201912.0385.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: dilated cardiomyopathy (DCM); hypertrophic cardiomyopathy (HCM); restrictive cardiomyopathy (RCM); arrhythmogenic right ventricular cardiomyopathy (ARVC); left ventricular non-compaction cardiomyopathy (LVNC); Duchenne muscular dystrophy; dystrophin; genome editing; CRISPR/Cas9; Cpf1 (Cas12a)
Online: 29 December 2019 (13:41:48 CET)
Cardiomyopathies are diseases of heart muscle, a significant percentage of which are genetic in origin. Cardiomyopathies can be classified as dilated, hypertrophic, restrictive, arrhythmogenic right ventricular or left ventricular non-compaction, although mixed morphologies are possible. A subset of neuromuscular disorders, notably Duchenne and Becker muscular dystrophies, are also characterized by cardiomyopathy aside from skeletal myopathy. The global burden of cardiomyopathies is certainly high, necessitating further research and novel therapies. Genome editing tools, which include zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPR) systems have emerged as increasingly important technologies in studying this group of cardiovascular disorders. In this review, we discuss the applications of genome editing in the understanding and treatment of cardiomyopathy. We also describe recent advances in genome editing that may help improve these applications, and some future prospects for genome editing in cardiomyopathy treatment.
COMMUNICATION | doi:10.20944/preprints202005.0253.v1
Subject: Life Sciences, Genetics Keywords: Cas9; Cas12a; Cpf1; zebrafish; gene knockout; repair outcome
Online: 15 May 2020 (10:16:55 CEST)
CRISPR/Cas genome editing is a widely used research technology. Its simplest variant is gene knockout resulting from reparation errors after introduction of dsDNA breaks by Cas nuclease. We compared the outcomes of the break repair by two commonly used nucleases (SpCas9 and LbCas12a) in zebrafish embryos to reveal if application of one nuclease is advantageous in comparison to the other. To address this question, we injected ribonucleoprotein complexes of nucleases and corresponding guide RNAs in zebrafish zygotes and three days later sequenced the target gene regions. We found that LbCas12a breaks resulted in longer deletions and more rare inserts, in comparison to those generated by SpCas9, while the editing efficiencies of both nucleases were the same. On the other hand, overlapping protospacers were shown to lead to similarities in repair outcome, although they were cut by two different nucleases. Thus, our results indicate that the repair outcome depends both on the nuclease mode of action and on protospacer sequence.
REVIEW | doi:10.20944/preprints201811.0018.v1
Subject: Life Sciences, Genetics Keywords: Duchenne muscular dystrophy (DMD); CRISPR/Cas9; exon skipping therapy; gene editing; human induced pluripotent stem cells (hiPSCs); immortalized patient muscle cells; mdx mice; humanized dystrophic mouse models; deltaE50-MD dog model
Online: 2 November 2018 (05:14:23 CET)
Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive neuromuscular disease prevalent in 1 in 3500 to 5000 males worldwide. As a result of mutations that interrupt the reading frame of the dystrophin gene (DMD), DMD is characterized by a loss of dystrophin protein which leads to decreased muscle membrane integrity, which increases susceptibility to degeneration. CRISPR/Cas9 technology has garnered interest as an avenue for DMD therapy due to its potential for permanent exon skipping, which can restore the disrupted DMD reading frame in DMD and lead to dystrophin restoration. An RNA-guided DNA endonuclease system, CRISPR/Cas9 allows for the targeted editing of specific sequences in the genome. The efficacy and safety of CRISPR/Cas9 as a therapy for DMD has been evaluated by numerous studies in vitro and in vivo, with varying rates of success. Despite the potential of CRISPR/Cas9-mediated gene editing for the long-term treatment of DMD, its translation into the clinic is currently challenged by issues such as off-targeting, immune response activation, and sub-optimal in vivo delivery. Its nature as being mostly a personalized form of therapy also limits applicability to DMD patients, who exhibit a wide spectrum of mutations. This review summarizes the various CRISPR/Cas9 strategies that have been tested in vitro and in vivo for the treatment of DMD. Perspectives on the approach will be provided, and the challenges faced by CRISPR/Cas9 in its road to the clinic will be briefly discussed.
REVIEW | doi:10.20944/preprints202104.0543.v1
Subject: Life Sciences, Biochemistry Keywords: Pathogenic relationship; Symbiotic relationship; LUCA; Horizontal gene transfer; Recombination; Transposition; Disease pathogenesis; CRISPR-Cas & Anti-CRISPR system
Online: 20 April 2021 (12:56:45 CEST)
Mutual survival among different species of living organisms is quite common in our living world. That mutual survival can produce symbiotic or parasitic relationship among different living organisms. But at the same time, some relationships are harmful to the living organisms creating pathogenic relationships. Why some mutual survivals are beneficial, whereas some relationships are harmful creating different diseases in the living world? That harmful or pathological relationship producing different diseases in both the animal and plant kingdom has been extensively studied by the scientific community several times under the heading of ‘Host-pathogen interaction’ and ‘Disease pathogenesis’. But it is still not clear why some mutual survivals are beneficial or non-harmful, whereas some co-survivals are harmful producing different disease conditions in the living world mainly due to different immune mediated reactions or direct toxic effect of substances produced by an organism. To find the answer to this question, we have to search retrospectively to the evolutionary pattern of our diverse living world. If it is assumed that we have originated from Last Universal Common Ancestor (LUCA) by different cumulative mutations, horizontal gene transfer, mobile genetic elements (MGE), transposition and natural selection, then it would be quite pragmatic to consider that two things were moving side by side in our ancient living world. On one hand it’s purpose was to create the diversification of both unicellular and multi-cellular living world and on the other hand it’s another purpose was to maintain the specific identity of the living organisms. It is the second purpose or the maintenance of specific identity that ultimately led to the development of Immune system.
ARTICLE | doi:10.20944/preprints202208.0048.v1
Subject: Life Sciences, Immunology Keywords: antibody; immunotherapy; CRISPR/HDR; FC optimization; hybridoma
Online: 2 August 2022 (08:10:26 CEST)
Regulatory T cells (Tregs) are major drivers behind immunosuppressive mechanisms and present a major hurdle for cancer therapy. Tregs are characterized by high expression of CD25, which is a potentially valuable target for Treg depletion to alleviate immune suppression. The preclinical anti-CD25 (αCD25) antibody, clone PC-61, has met with modest anti-tumor activity, due to its capacity to clear Tregs from circulation and lymph nodes but not those that reside in the tumor. Optimization of the Fc domain of this antibody clone has been shown to enhance intratumoral Treg depletion capacity. Here, we generated a stable cell line that produces optimized recombinant Treg depleting antibodies. A genome engineering strategy in which CRISPR-Cas9 was combined with homology directed repair (CRISPR-HDR) was utilized to optimize the Fc domain of the hybridoma PC-61 for effector functions by switching it from the original rat IgG1 to a mouse IgG2a isotype. In a syngeneic tumor mouse model the resulting αCD25-m2a antibody mediated effective depletion of tumor resident Tregs leading to a high effector T cell (Teff) to Treg ratio. Moreover, combination of the αCD25-m2a with αPD-L1 treatment augmented tumor eradication in mice, demonstrating the potential for αCD25 as a cancer immunotherapy.
ARTICLE | doi:10.20944/preprints202201.0296.v1
Online: 20 January 2022 (10:28:07 CET)
Human gut microbiome is associated with various diseases, including autism spectrum disorders (ASD). Variations of the taxonomical composition in the gut microbiome of children with ASD have been observed repeatedly. However, features and parameters of the CRISPR-Cas systems in the gut microbiome of children with ASD have not been investigated yet. Here we demonstrate such an analysis in comparison with the healthy microbiome. For the identification of CRISPR-Cas systems, we used a combination of the publicly available tools suited for completed genomes with subsequent filtrations. In all considered datasets, the microbiomes of children with ASD contained fewer arrays per Gb of assembly, than the control group, but the arrays included more spacers on average. These patterns were observed systematically in our datasets, although their statistical significance hardly matched the thresholds. CRISPR arrays from the microbiomes of children with ASD differed from the control group neither in the fractions of spacers with protospacers from known genomes, nor in the sets of known bacteriophages providing protospacers. The majority of bacterial protospacers of the gut microbiome systems for both children with ASD and the healthy ones was located in the prophage islands.
ARTICLE | doi:10.20944/preprints202112.0372.v1
Online: 22 December 2021 (14:45:23 CET)
The production of bio-chemicals requires the use of microbial strains with efficient substrate conversion and excellent environmental robustness, such as Bacillus coagulans spp. So far the genomes of about 50 strains have been sequenced. Herein, we report a comparative genomic analysis of nine strains on the full repertoire of CAZymes, secretion systems, and resistance mechanisms to environmental challenges. Moreover, B. coagulans Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) immune system along with CRISPR-associated Cas) genes, was also analysed. Overall, this study expands our understanding of the strains genomic diversity of B. coagulans to fully exploit its potential in biotechnological applications.
ARTICLE | doi:10.20944/preprints202112.0246.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: CRISPR; LNP; formulation; NHEJ; HDR; AF4; delivery
Online: 14 December 2021 (18:24:56 CET)
The CRISPR-Cas9 system is an emerging therapeutic tool with the potential to correct diverse ge-netic disorders. However, for gene therapy applications an efficient delivery vehicle is required, capable of delivering the CRISPR-Cas9 components into the cytosol of the intended target cell population. Once there, the ribonucleoprotein complex (RNP) can be transported into the nucleus. Lipid nanoparticles (LNP) serve as promising candidates for delivery of CRISPR-Cas9 RNP. These delivery vehicles have been optimized for the delivery of nucleic acids, such as mRNA. Co-delivery of Cas9 encoding mRNA with the accompanying sgRNA leads to translation of the Cas9 protein and formation of the Cas9 RNP inside the cell. Only recently, direct delivery of the CRISPR-Cas9 RNP complexes has been explored, which requires adjustments to the LNP formulation. In this study, the importance of buffer composition and cationic charge during RNP and ssDNA en-trapment in LNP are demonstrated. After optimizing several formulation parameters, LNP were prepared that were colloidally stable in human plasma and efficiently deliver the SpCas9 RNP and ssDNA for HDR-correction in reporter cells. Under optimal formulation conditions, gene knock-out and gene correction efficiencies as high as 80% and 20%, respectively were achieved at nanomolar CRISPR-Cas9 RNP concentrations.
ARTICLE | doi:10.20944/preprints202111.0210.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: CRISPR-Cas, Nucleic acid detection, Klebsiella pneumonia
Online: 11 November 2021 (12:57:06 CET)
Klebsiella pneumonia (K. pneumoniae) is a Gram-negative bacterium that causes nosocomial infections in the lung, bloodstream, and urinary tract. Therefore, detecting K. pneumoniae in early time is important in preventing severe infections. However, clinical detection of K. pneumoniae requires a long time of agar plate culture. Nucleic acid detection like qPCR is precise but requires expensive equipment. Recent research reveals that collateral cleavage activity of CRISPR-LbCas12a has been applied in nucleic acid detection. In this study, PCR combined with CRISPR-LbCas12a targeting the K. pneumoniae system was established. This system showed excellent detection specificity and sensitivity in both bench work and clinical samples. Due to its advantages, its application can meet different detection requirements in health centers where qPCR is not accessible.
ARTICLE | doi:10.20944/preprints202109.0362.v1
Online: 21 September 2021 (12:34:20 CEST)
Multiplex genome editing may induce genotoxicity and chromosomal rearrangements due to double-strand DNA breaks at multiple loci simultaneously induced by programmable nucleases, including CRISPR/Cas9. However, recently developed base-editing systems can directly substitute target sequences without double-strand breaks. Thus, the base-editing system is expected to be a safer method for multiplex genome-editing platforms for livestock. Target-AID is a base editing system composed of PmCDA1, a cytidine deaminase from sea lampreys, fused to Cas9 nickase. It can be used to substitute cytosine for thymine in 3-5 base editing windows, 18 bases upstream of the protospacer-adjacent motif site. In the current study, we demonstrated Target-AID-mediated base editing in porcine cells for the first time. We targeted multiple loci in the porcine genome using the Target-AID system and successfully induced target-specific base substitutions with up to 63.15% efficiency. This system can be used for the further production of various genome-engineered pigs.
REVIEW | doi:10.20944/preprints202011.0603.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: genome editing, agriculture, crispr, talen, specificity, off-target
Online: 24 November 2020 (08:35:00 CET)
We are in a new chapter of crop and livestock improvement with the emergence of genome editing. This latest generation of molecular tools can be used to make targeted changes in a genome including insertions, deletions, and mutations. With new advances comes new risks for unintended changes and impacts, thus the need for appropriate risk assessment for product development and to inform regulatory measures. Though CRISPR/Cas has arisen as the predominant technology, there are multiple types of genome editing tools each with pros and cons depending on the organism and desired outcome. Furthermore, each editing tool differs in specificity as they may edit non-intended sites, referred to as off-target edits. The consensus of the agricultural editing community is to avoid off-target editing through design and detection, instead of determining whether off-target editing in each case is detrimental. The design of a targeting component, the tool chosen, and the identification of the edit(s) made are the critical factors in avoiding off-target edits and confirming intended edits in final products that are released commercially. The limited amount of head-to-head comparisons of genome editing tools in diverse crops and livestock make it difficult to develop broad conclusions and best practices, which is further compounded by the diversity of techniques, targets, and processes. Developers and breeders should consult the literature and test as needed to determine which editing technology will be the most effective for their purposes, especially as more tools with altered efficiency and specificity become available. Yet, the lack of off-target edits in studies that employed careful design of targeting components followed by wide testing for on- and off-target edits bodes well for the use of genome editing with proper precautions of target selection and screening.
REVIEW | doi:10.20944/preprints202111.0235.v1
Subject: Life Sciences, Biochemistry Keywords: Cystic Fibrosis; CFTR gene; CRISPR/Cas; pegRNA; Cationic Liposome
Online: 12 November 2021 (15:34:03 CET)
Cystic Fibrosis is a rare genetic disease that affects the transmission of chloride ions due to mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene. Even though there are nearly 2000 mutations identified to be related to the condition, the most common mutation is F508del; deletion of a phenylalanine residue at 508. On the other hand, G542X which is a Class I mutation is also found very commonly and there are no modulator treatments available for it. Furthermore, it was investigated that R553X mutation can as well be corrected simultaneously with G542X mutation. Therefore, the main focus is on designing a gene therapy project that can correct all these three mutations at once by utilizing the prime editing technique via lipid-based delivery. In this way, the mutations can be edited through plasmids that were designed containing 2 pegRNAs and the Cas enzyme. To implement such an approach efficiently, both ex vivo, an animal model, and in vivo steps are to be designed. For the cell line, fibroblasts are selected due to their simplicity and low cost. The animal model of the experiment is determined to be a ferret concerning the high similarity to the human's CFTR protein and finally, the procedure will follow on a direct application in human Cystic Fibrosis patients. The plasmids are thought to be delivered through a cationic liposome that will reach the lungs with the aid of a nebulizer. At the last stage of the experimental procedure, Sanger Sequencing will be done to see if the desired edit within the CFTR has been performed successfully, and Next Generation Sequencing will be executed to see if there has been an off-target mutation in the remainder of the genome. Whereas for detecting the presence and expression of CFTR protein in humans, immunodetection with flow cytometry will be conducted.
REVIEW | doi:10.20944/preprints201810.0714.v1
Subject: Biology, Other Keywords: ncRNA; cis-encoded ncRNA; trans-encoded ncRNA; riboswitch; CRISPR.
Online: 30 October 2018 (08:48:47 CET)
Genes encoding regulatory RNAs known as short RNAs (sRNAs) or non-coding sRNAs (ncRNAs), modulate physiological responses through different mechanisms, through RNA-RNA interaction or RNA-protein interaction. These molecules transcribed in trans and in cis relative to the target RNA. They are located between the coding regions of proteins, i.e., in the intergenic regions of the genome and show signals of promoters and termini sequences generally Rho-independent. The size of the ncRNAs genes ranges from ~ 50 to ~ 500 nucleotides and several transcripts are processed by RNase with smaller end products, which modulate physiological responses through different mechanisms, by RNA-RNA interaction or RNA-protein interactions and some interactions may be stabilized by the Hfq chaperone. The Riboswitches constitute another class of ncRNAs, located in the 5'UTR region of an mRNA that promote transcriptional regulation through their interaction with a linker molecule. Recently, in prokaryotes, CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) regions have described, which repeats of sequences of palindromic bases are. Each replicate consists of short segments of "spacer DNA" from exposures prior to a bacteriophage virus or exogenous plasmid. The CRISPR system consists of an immune system of resistance to exogenous molecules.
ARTICLE | doi:10.20944/preprints201811.0279.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: copper importers CTR1 and DMT1; CRICPR-Cas9; cisplatin; silver; signaling; copper homeodynamics
Online: 12 November 2018 (10:05:01 CET)
Copper, the highly toxicity micronutrient, plays two essential roles: it is a catalytic and structural cofactor for Cu-dependent enzymes, and it acts as a secondary messenger. In the cells, copper is imported by CTR1, a transmembrane high-affinity copper importer, and DMT1 (divalent metal transporter). In cytosol, enzyme-specific chaperones receive copper from CTR1 C-terminus and deliver it to their apoenzymes. DMT1 cannot be a donor of catalytic copper because it does not have cytosol domain which is required for copper transfer to the Cu-chaperons and following to cuproenzymes. Here we assume that DMT1 can mediate copper way required for regulatory copper pool. To verify this thought, we used CRISPR/Cas9 to generate H1299 cell line with CTR1 or DMT1 single knockout (KO) and CTR1/DMT1 double knockout (DKO). To confirm KOs of the genes qRT-PCR were used. Two independent clones for each gene were selected for further studies. In CTR1-KO cells, expression of the DMT1 gene was significantly increased. In subcellular compartments, copper concentration decreased dramatically in DKO cells. CTR1-KO cells, but not DMT1-KO, demonstrated reduced sensitivity to cisplatin and silver ions, agents that enter the cell through CTR1. The expression of genes, whose protein products require copper: HIF1α, XIAP, COMMD1, CCS, Cp, but not SOD1 and NF-kB, changed their level. Perhaps these data will help to understand how the disturbances of copper homeodynamics lead to the development of neurodegenerative and oncological disorders. Possibility of using CTR1 KO and DMT1 KO cells to study homeodynamics of catalytic and signaling copper selectively is discussed.
REVIEW | doi:10.20944/preprints202212.0184.v1
Subject: Biology, Plant Sciences Keywords: CRISPR; genome editing; gene editing; forage grass; abiotic stress; plant
Online: 12 December 2022 (01:38:47 CET)
Due to an increase in the consumption of food, feed, and fuel and to meet global food security needs for the rapidly growing human population, there is a necessity to obtain high-yielding crops that can adapt to future climate changes. Currently, the main feed source used for ruminant livestock production is forage grasses. In temperate climate zones, perennial grasses grown for feed are widely distributed and tend to suffer under unfavorable environmental conditions. Gene editing has been shown to be an effective tool for the development of abiotic stress-resistant plants. The highly versatile CRISPR-Cas system enables increasingly complex modifications in genomes while maintaining precision and low off-target frequency mutations. In this review, we provide an overview of forage grass species that have been subjected to gene editing. We offer a perspective view on the generation of plants resilient to abiotic stresses. Due to the broad factors contributing to these stresses the review focuses on drought, salt, heat, and cold stresses. The application of new genomic techniques (e.g., CRISPR-Cas) allows addressing several challenges caused by climate change and abiotic stresses for developing forage grass cultivars with improved adaptation to the future climatic conditions. Gene editing will contribute towards developing safe and sustainable food systems.
REVIEW | doi:10.20944/preprints202209.0454.v1
Subject: Biology, Entomology Keywords: CRISPR-Cas technology; pest management; plant stress resistance; insect resistance
Online: 29 September 2022 (07:08:41 CEST)
Global crop yield and food security are being threatened by phytophagous insects. Innovative methods are required to increase agricultural output while reducing reliance on hazardous synthetic insecticides. It appears to be quite effective at reducing production costs and boosting farm profitability to use the ground-breaking CRISPR-Cas technology to create plants that are insect resistant. In contrast, this new technique can modify an insect's genome to either produce gene drive or get beyond an insect's tolerance to various insecticides. This paper reviews and critically discusses the use of CRISPR-Cas genome editing technology in long-term insect pest management. The emphasis of this review is on the prospective uses of the CRISPR-Cas system for insect stress management in crop production by creating genome-edited crops and insects. The potential and difficulties of using CRISPR-Cas technology to reduce pest stress in crop plants are critically examined and discussed.
ARTICLE | doi:10.20944/preprints202107.0457.v1
Subject: Life Sciences, Microbiology Keywords: Latilactobacillus sakei; comparative genomics; carbohydrate utilization; antibiotic tolerance; CRISPR-Cas
Online: 20 July 2021 (15:02:42 CEST)
Increasing attention has been paid to the potential probiotic effects of Latilactobacillus sakei. To explore the genetic diversity of L. sakei, 14 strains isolated from different niches (feces, fermented kimchi and meat products) and 54 published strains were compared and analyzed. The results showed that the average genome size and GC content of L. sakei were 1.98Mb and 41.22%, respectively. Its core genome mainly encodes translation and transcription, amino acid synthesis, glucose metabolism and defense functions. L. sakei has an open pan-genomic characteristics, and its pan-gene curve shows an upward trend. L. sakei has open pan-genome feature, and its pan-genome curve is on the rise. The genetic diversity of L. sakei is mainly reflected in carbohydrate utilization, antibiotic tolerance, and immune/competition-related factors, such as clustering regular interval short palindromic repeat sequence (CRISPR)-Cas. The CRISPR system is mainly IIA type, and a few are IIC types. This work provides a basis for the study of this species.
REVIEW | doi:10.20944/preprints202201.0265.v1
Subject: Life Sciences, Genetics Keywords: CRISPR; gene editing; Duchenne muscular dystrophy (DMD); exon skipping; NHEJ; dystrophin
Online: 18 January 2022 (17:30:37 CET)
Duchenne muscular dystrophy (DMD) is an X-linked recessive neuromuscular disorder with a prevalence of approximately 1 in 3,500-5,000 males. DMD manifests as childhood-onset muscle degeneration, followed by loss of ambulation, cardiomyopathy, and death in early adulthood due to a lack of functional dystrophin protein. Out-of-frame mutations in the dystrophin gene are the most common underlying cause of DMD. Gene editing via the clustered regularly interspaced short palindromic repeats (CRISPR) system is a promising therapeutic for DMD, as it can permanently correct DMD mutations and thus restore the reading frame, allowing for the production of functional dystrophin. The specific mechanism of gene editing can vary based on a variety of factors such as the number of cuts generated by CRISPR, the presence of an exogenous DNA template, or the current cell cycle stage. CRISPR-mediated gene editing for DMD has been tested both in vitro and in vivo, with many of these studies discussed herein. Additionally, novel modifications to the CRISPR system such as base or prime editors allow for more precise gene editing. Despite recent advances, limitations remain including delivery efficiency, off-target mutagenesis, and long-term maintenance of dystrophin. Further studies focusing on safety and accuracy of the CRISPR system are necessary prior to clinical translation.
REVIEW | doi:10.20944/preprints202004.0080.v1
Subject: Life Sciences, Biotechnology Keywords: cancer-related viruses; CRISPR-Cas diagnostic tools; DETECTR; infectious disease; SHERLOCKv2
Online: 7 April 2020 (09:43:22 CEST)
Sensitive and precise nucleic acid detection is critical for clinical diagnostics and biotechnological advancements. Diagnostic in infectious disease field is very unique from diagnosing any other disease, that is time is of the essence; in outbreaks people die even with each passing hour in some cases, if the correct diagnosis wasn't make; for example Zika in particularly is a very challenging virus to diagnose, because it's in very few numbers of copies in the infected person, so it need high sensitive diagnostic approach to spot it, In particular, the advanced tools SHERLOCKv2 and DETECTR, give almost an immediate detection of attomolar amounts of pathogenic nucleic acids with specificity similar to that of PCR but with slight technical settings and that will guide the correct intervention for the patient. SHERLOCKv2 and DETECTR technologies are game changers for our ability to identify infectious disease and rapid detection of tumor DNA or cancer-related viruses with ultra-sensitive tests that don’t require a lot of complicated processing to go through. In this paper, we will review cutting-edge infectious disease diagnosis by CRISPR-Cas systems.
OPINION | doi:10.20944/preprints201608.0016.v1
Subject: Life Sciences, Molecular Biology Keywords: parallel DNA; antiparallel DNA; PCR; CRISPR; nucleic acid hybridization; microarray; siRNA
Online: 2 August 2016 (10:42:27 CEST)
Many fundamental molecular techniques (PCR, Microarray, Southern and northern hybridization, siRNA, CRISPR/Cas9 etc.) developed so far shows errors. I wish to highlight these molecular techniques are developed on basis of Watson-Crick DNA model, ignoring the concept of parallel stranded DNA. Through this opinion article, I wish to highlight specificity and accuracy of these molecular techniques can be enhanced by considering both parallel and anti parallel hybridization of DNA. Hopefully my views will also solve issue of irreproducibility in life science research.
REVIEW | doi:10.20944/preprints202207.0404.v1
Subject: Biology, Plant Sciences Keywords: Abiotic stress; biotic stress; biotechnology; climate change; CRISPR; crop improvement; genome editing
Online: 26 July 2022 (10:44:22 CEST)
Climate change poses a serious threat to global agricultural activity and food production. To address this issue, plant genome editing technologies have been developed to provide an alternative solution for crop improvement. Unlike conventional breeding techniques (e.g., selective breeding and mutation breeding), modern genome editing tools offer more targeted and specific alterations of the plant genome to produce crops with desired traits, such as higher yield and/or stronger resilience to the changing environment. In this review, we discuss the current development and future applications of genome editing technologies in mitigating the impacts of biotic and abiotic stresses on agriculture. We focus specifically on the CRISPR/Cas system, which has been the center of attention in the last few years as a revolutionary genome-editing tool in various species. We also conducted a bibliographic analysis on CRISPR-related papers published from 2012 to 2021 (10 years) to identify trends and possible gaps in the CRISPR/Cas-related plant research. In addition, this review article outlines the current shortcomings and challenges of employing genome editing technologies in agriculture with notes on future prospective. We believe combining conventional and more innovative technologies in agriculture would be the key to optimizing crop improvement beyond the limitations of traditional agricultural practices.
ARTICLE | doi:10.20944/preprints202105.0333.v1
Subject: Life Sciences, Biochemistry Keywords: genome editing; CRISPR; protoplast; , targeted mutagenesis; TREX2; construct validation; transi-ent expression
Online: 14 May 2021 (13:44:26 CEST)
Cas endonuclease-mediated genome editing provides a long-awaited molecular biological approach to the modification of predefined genomic target sequences in living organisms. Although cas9/guide (g)RNA constructs are straightforward to assemble and can be customized to target virtually any site in the plant genome, the implementation of this technology can be cumbersome, especially in species like Triticale that are difficult to transform, for which only limited genome information is available and/or which carry comparatively large genomes. To cope with these challenges, we have pre-validated cas9/gRNA constructs (1) by frameshift restitution of a reporter gene co-introduced by ballistic DNA transfer to barley epidermis cells, and (2) via transfection in Triticale protoplasts followed by either a T7E1-based cleavage assay or by deep-sequencing of target-specific PCR amplicons. For exemplification, we addressed the Triticale ABA 8’-hydroxylase 1 gene, one of the putative determinants of pre-harvest sprouting of grains. We further show that in-del induction frequency in Triticale can be increased by TREX2 nuclease activity, which holds true for both well- and poorly performing gRNAs. The presented results constitute a sound basis for the targeted induction of heritable modifications in Triticale genes.
REVIEW | doi:10.20944/preprints202003.0048.v1
Subject: Life Sciences, Genetics Keywords: Duchenne muscular dystrophy; CRISPR; animal models; in vivo testing; dystrophin; mutant generation
Online: 4 March 2020 (04:58:48 CET)
Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive neuromuscular disorder most commonly caused by mutations disrupting the reading frame of the dystrophin (DMD) gene. DMD codes for dystrophin, which is critical for maintaining the integrity of muscle cell membranes. Without dystrophin, muscle cells receive heightened mechanical stress, becoming more susceptible to damage. An active body of research continues to explore therapeutic treatments for DMD as well as to further our understanding of the disease. These efforts rely on having reliable animal models that accurately recapitulate disease presentation in humans. While current animal models of DMD have served this purpose quite well, each comes with their own limitations. To help overcome this, clustered regularly interspaced short palindromic repeats (CRISPR)-based technology has been extremely useful in creating novel animal models for DMD. This review focuses on animal models developed for DMD that have been created using CRISPR, their advantages and disadvantages as well as their applications in the DMD field.
ARTICLE | doi:10.20944/preprints202002.0238.v1
Subject: Biology, Other Keywords: oxytocin; cellular morphology; neurite outgrowth; neurite retraction; autism; MEF2A; CRISPR-Cas; hyperconnectivity
Online: 17 February 2020 (03:44:01 CET)
The neuropeptide oxytocin (OT) is a well-described modulator of socio-emotional traits, such as anxiety, stress, social behavior, and pair-bonding, however, when dysregulated, it is associated with adverse psychiatric traits, like various aspects of autism spectrum disorder (ASD). In this study, we identify the transcription factor MEF2A as the common link between OT and cellular changes symptomatic for ASD, encompassing neuronal morphology, connectivity, and mitochondrial function. We provide evidence for MEF2A as the decisive factor defining the cellular response to OT: while OT induces neurite retraction in MEF2A expressing neurons, OT causes neurite outgrowth in absence of MEF2A. A CRISPR-Cas-mediated knockout of MEF2A and retransfection of an active version or permanently inactive mutant, respectively, validated our findings. We also identified the phosphatase calcineurin as the main upstream regulator of OT-induced MEF2A signaling. Further, MEF2A signaling dampens mitochondrial functioning in neurons, as MEF2A knockout cells show increased maximal cellular respiration, spare-respiratory capacity, and total cellular ATP. In summary, we reveal a central role for OT-induced MEF2A as major regulator of cellular morphology as well as neuronal connectivity and mitochondrial functioning, with broad implications for a potential treatment of disorders based on morphological alterations or mitochondrial dysfunction.
REVIEW | doi:10.20944/preprints201906.0032.v1
Subject: Life Sciences, Molecular Biology Keywords: nucleic acids analogs, antisense, CRISPR, antibiotic resistance, myotonic dystrophy, cholesterol, hematologic malignancy,
Online: 5 June 2019 (08:11:12 CEST)
Oligonucleotides are key compounds widely used for research, diagnostics, and therapeutics. The rapid increase in oligonucleotide-based applications, together with the progress in nucleic acids research, led to the design of nucleotide analogs that when being part of these oligomers enhance their efficiency, bioavailability, or stability. One of the most useful nucleotide analogs are the first-generation bridge nucleic acids (BNA), also known as locked nucleic acids (LNA), which were used in combination with ribonucleotides, deoxyribonucleotides, or other analogs to construct oligomers with diverse applications. However, there is still room to improve their efficiency, bioavailability, stability, and, importantly, toxicity. A second generation BNA, BNANC (2'-O,4'-aminoethylene bridged nucleic acid), has been recently made available. Oligomers containing these analogs not only showed less toxicity when compared to LNA-containing compounds but in some cases also exhibited higher specificity. Although there are still few applications where BNANC-containing compounds were researched, the results are very promising warranting more efforts in incorporating these analogs for other applications. Furthermore, newer BNA compounds will be introduced in the near future offering great hope to oligonucleotide-based fields of research and applications.
ARTICLE | doi:10.20944/preprints201902.0266.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: β2-adrenergic receptor; cAMP; cardiac myocytes; CRISPR; Epac1; fibrosis; osteopontin; signal transduction
Online: 1 March 2019 (05:15:17 CET)
Cardiac β2-adrenergic receptors (ARs) are known to inhibit collagen production and fibrosis in cardiac fibroblasts and myocytes. The β2AR is a Gs protein-coupled receptor (GPCR) and, upon its activation, stimulates generation of cyclic 3', 5'-adenosine monophosphate (cAMP). cAMP has two effectors: protein kinase A (PKA) and the exchange protein directly activated by cAMP (Epac). Epac1 has been shown to inhibit cardiac fibroblast activation and fibrosis. Osteopontin (OPN) is a ubiquitous pro-inﬂammatory cytokine, mediating also fibrosis in several tissues, including the heart. OPN underlies several cardiovascular pathologies, including atherosclerosis and cardiac adverse remodeling. We have found that the cardiotoxic hormone aldosterone transcriptionally upregulates OPN in H9c2 rat cardiac myoblasts, an effect prevented by endogenous β2AR activation. Additionally, CRISPR-mediated OPN deletion enhances cAMP generation in response to both b1AR and β2AR activation in H9c2 cardiomyocytes, leading to upregulation of Epac1 protein levels. These effects render β2AR stimulation capable of completely abrogating transforming growth factor (TGF)-β-dependent fibrosis in OPN-lacking H9c2 cardiomyocytes. Finally, OPN interacts constitutively with Gas subunits in H9c2 cardiac cells. Thus, we have uncovered a direct inhibitory role of OPN in cardiac β2AR anti-fibrotic signaling via cAMP/Epac1. OPN blockade could be of value in the treatment and/or prevention of cardiac fibrosis.
ARTICLE | doi:10.20944/preprints202109.0051.v1
Subject: Biology, Entomology Keywords: Helicoverpa zea; Bollworm; CRISPR; Cry1A; Bt Toxin; Genome Editing; Knockout; Functional Genomics; Resistance
Online: 3 September 2021 (08:19:44 CEST)
Members of the insect ATP binding cassette transporter subfamily C2 (ABCC2) in several moth species are known as receptors for the Cry1Ac insecticidal protein from Bacillus thuringiensis (Bt). Mutations that abolish the functional domains of ABCC2 are known to cause resistance to Cry1Ac, although the reported levels of resistance vary widely depending on insect species. In this study, the function of the ABCC2 gene as putative Cry1Ac receptor in Helicoverpa zea, a major pest of over 300 crops, was evaluated using CRISPR/Cas9 to progressively eliminate different functional ABCC2 domains. Results from bioassays with edited insect lines support that muta-tions in ABCC2 was associated with Cry1Ac resistance ratios (RR) ranging from 7.3- to 39.8-fold. No significant differences in susceptibility to Cry1Ac were detected between H. zea with partial or complete ABCC2 knockout, although highest levels of tolerance were observed when knocking out half of ABCC2. Based on >500-1,000-fold RRs reported in similar studies for closely related moth species, the low RRs observed in H. zea knockouts support that ABCC2 is not a major Cry1Ac receptor in this insect.
REVIEW | doi:10.20944/preprints202212.0231.v1
Subject: Life Sciences, Biotechnology Keywords: methylerythritol phosphate (MEP) pathway; photosynthesis; isoprenoids; lipids; biofuels; gene editing; CRISPR; riboswitch; riboregulators; nanocompartments
Online: 13 December 2022 (07:22:52 CET)
Cyanobacteria are photosynthetic microorganisms capable of using solar energy to convert CO2 and H2O into O2 and energy-rich organic compounds, thus enabling sustainable production of a wide range of bio-products. More and more strains of cyanobacteria are identified that show great promise as cell platforms for the generation of bioproducts. However, strain development is still required to optimize their biosynthesis and increase titers for industrial applications. This review describes the most well-known and newest most promising strains available to the community and gives an overview of current cyanobacterial biotechnology and the latest innovative strategies used for engineering cyanobacteria. We summarize advanced synthetic biology tools for modulating gene expression and their use in metabolic pathway engineering to increase the production of value-added compounds, such as terpenoids, fatty acids, and sugars, to provide a go-to source for scientists starting research in cyanobacterial metabolic engineering.
REVIEW | doi:10.20944/preprints202203.0089.v1
Subject: Life Sciences, Biotechnology Keywords: CRISPR-Cas; SARS-CoV-2; molecular diagnostics; isothermal amplification; comparative analysis; nucleic acid detection
Online: 7 March 2022 (04:53:25 CET)
The emergence of the COVID-19 pandemics prompted a fast development of novel diagnostic methods of the etiologic virus SARS-CoV-2. Methods based on CRISPR-Cas systems have been particularly promising because they can achieve a similar sensitivity and specificity to the golden standard RT-qPCR, especially when coupled to an isothermal pre-amplification step. Furthermore, they have also solved inherent limitations of RT-qPCR that impede its decentralized use and deployment in the field, such as the need for expensive equipment, high cost per reaction, and delivery of results in hours, among others. In this review, we evaluate publicly available methods to detect SARS-CoV-2 that are based on CRISPR-Cas and isothermal amplification. We critically analyze the steps required to obtain a successful result from clinical samples and pinpoint key experimental conditions and parameters that could be optimized or modified to improve clinical and analytical outputs. The COVID outbreak has propelled intensive research in a short time, which is paving the way to develop effective and very promising CRISPR-Cas systems for the precise detection of SARS-CoV-2. This review could also serve as an introductory guide to new labs delving into this technology.
REVIEW | doi:10.20944/preprints202011.0667.v1
Subject: Life Sciences, Biochemistry Keywords: Plant breeding; Genome editing; Molecular breeding; Prime editing; Base editing; CRISPR Cas; Epigenetics; Speed breeding
Online: 26 November 2020 (11:17:56 CET)
Conventional plant breeding methods exploit already existing genomic variation in plants to develop a variety in 8 to 10 years, which can decrease the genetic variability of the plant’s genome. The ever-increasing food demand for cereals crops cannot be met by traditional breeding methods. In order to increase food production in less time, there is a dire need to improve breeding methods. Several conventional and molecular breeding methods are being used to improve the crops traits. Molecular researchers have developed new genome editing tools like CRISPR/Cas9, CRISPR/Cpf1, prime editing, base editing, dcas9 epigenetic modification, and several other transgene-free genomes editing approaches. These genome editing tools can improve the desired traits precisely and efficiently. Moreover, a newly developed breeding method “Speed Breeding” has revolutionized the agriculture by shortening the crop cycle. It can produce 5-6 generations of cereals in a year. In this review, we have summarized all these conventional and molecular breeding approaches to improve cereal crops.
REVIEW | doi:10.20944/preprints201905.0386.v1
Subject: Life Sciences, Immunology Keywords: CRISPR, clonal selection, totipotent, multipotent, T cell receptors, B cell receptors, precommitted, lymphocyte, T cell vaccine, T cell vaccination
Online: 31 May 2019 (11:12:33 CEST)
Transfer factor is the name given to material derived from activated lymphocytes that is probably composed of a complex of a peptide and a short segment of RNA and which has the reported ability to transfer specific T cell immunity to uncommitted lymphocytes. Many independent groups around the world reported isolating transfer factors between 1955 and 1990 and demonstrating their ability to transfer passive immunity from one animal or individual to another, often within 24 hours of inoculation. Such activity is potentially revolutionary both in making T cell vaccines readily manufacturable and also because the existence of transfer factors would undermine the basic assumptions of the clonal selection theory, which currently dominates immunological theory. Unfortunately, lack of the microanalytical and synthetic techniques required to properly identify transfer factors, combined with safety factors associated with it derivation from blood sources susceptible to HIV and prion infections, put an end to transfer factor research after 1990. This paper reviews the evidence supporting transfer factor activity and suggests that this potentially revolutionary concept be resurrected and subjected to renewed scrutiny in light of CRISPR-Cas mechanisms and because of its potential to make possible T cell vaccination and provide a novel basis for understanding immunological function.
CONCEPT PAPER | doi:10.20944/preprints202009.0723.v1
Subject: Life Sciences, Biochemistry Keywords: Glycogen Storage Disease Type 1a, Glucose-6-phosphatase Catalytic Subunit (G6PC), Glucose-6-phosphatase (G6Pase), prime editing, mRNA delivery, CRISPR
Online: 30 September 2020 (08:05:17 CEST)
One of the rare diseases throughout the world is Glycogen Storage Disease, which appears due to problems in glycogen metabolism. Among various subtypes of GSD, GSD Type 1a is the most abundant one of GSD Type 1, seen in approximately 80% and caused by different kinds of mutations in the Glucose-6-Phosphatase Catalytic Subunit (G6PC) gene in human chromosome 17q21. G6PC gene encodes for glucose-6-phosphatase (G6Pase) protein, which cleaves glucose-6-phosphate into glucose and inorganic phosphate (Pi), and GSD Type 1a patients fail to breakdown glucose-6-phosphate due to several mutations in the G6PC gene. In our study, we aim to create new therapeutic approaches for GSD 1a. We collected mutation data of 57 GSD Type 1a patients from Turkey. According to the data, 16 types of mutations were observed in the G6PC gene. Allele frequencies of these mutations are calculated as 59% for R83C/H, 11% for W160*, 7% for G270V, and 28% for others which have less frequency. Up to now, the tertiary protein structure of G6Pase has not been structured yet. To understand the possible impacts of these mutations, we statistically obtained possible tertiary structure predictions of G6Pase by running 5 different tools. At the end of the study, we suggest two effective and promising gene therapy methods for GSD Type 1a, Prime Editing for R83C/H mutations, and mRNA delivery for other mutations, in addition to a promising, commercially available drug suggestion for patients with W160*, W86*, and S15* mutations, although the drug belongs to another disease.
Subject: Social Sciences, Economics Keywords: new plant engineering techniques (NPETs); new breeding techniques (NBTs); GMO; transgenic; genome editing; gene editing; cisgenic; CRISPR; RNAi; willingness to pay (WTP)
Online: 2 September 2021 (12:46:50 CEST)
We review the emerging international body of evidence on attitudes and willingness to pay (WTP) for novel foods produced with New Plant Engineering Techniques (NPETs). NPETs include genome/gene editing, cisgenesis, intragenesis, RNA interference and others. These novel foods are often beneficial for the environment and human health and more sustainable under increasingly prevalent climate extremes. These techniques can also improve animal welfare and disease resistance when applied to animals. Despite these promising attributes, evidence suggests that many, but not all consumers, discount these novel foods relative to conventional ones. Our systematic review sorts out findings to identify conditioning factors which can increase the acceptance of and WTP for these novel foods in a significant segment of consumers. International patterns of acceptance are identified. We also analyze how information and knowledge interact with consumer acceptance of these novel foods and technologies. Heterogeneity of consumers across cultures and borders, and in attitudes towards science and innovation emerges as key determinants of acceptance and WTP. Acceptance and WTP tend to increase when beneficial attributes—as opposed to producer-oriented cost-saving attributes—are generated by NPETs. NPETs improved foods are systematically less discounted than transgenic foods. Most of the valuation elicitations are based on hypothetical experiments and surveys and await validation through revealed preferences in actual purchases in food retailing environments.
HYPOTHESIS | doi:10.20944/preprints202010.0199.v1
Subject: Life Sciences, Biochemistry Keywords: CRISPR interference; error-prone polymerase chain reaction; ribosomal proteins; ribosome; viability assay; Bacillus subtilis; Escherichia coli; sequence space; conformational space; mutational map
Online: 9 October 2020 (12:24:14 CEST)
Ribosomes are macromolecular complexes important to protein translation, and thus, essential to life. Comprising an ensemble of ribosomal proteins and RNA molecules, ribosomes are conserved in structure and function across all domains of life, but recent structural studies have revealed differentiated structures of ribosomes from bacterial, archaea and eukaryotes. Additionally, unique ribosomal protein mass fingerprints have been found for individual species; thereby, indicating that ribosomes are differentiated in structure amongst different species. Given that structure defines function, differentiated function likely exists amongst ribosomes of different species, which could manifest as differences in translation efficiency that could impact on cell growth rate. But ribosomal proteins also hold phylogenetic significance in informing the evolutionary trajectory of each species. Such ribosomal proteins are thus not highly conserved and offers sufficient sequence space for the evolution of differentiated structure and function in different species. Using ribosomal proteins that hold phylogenetic significance as templates, this study sought to understand the mutational and conformational limits that define functional ribosomes. Specifically, ribosomal proteins in Bacillus subtilis that hold phylogenetic cues would be mutated through error-prone polymerase chain reaction to generate variants that are subsequently transformed into Escherichia coli. To help assess the functional properties of the heterologous ribosomal proteins, endogenous ribosomal protein genes would be inactivated by multiplex CRISPR interference. Since variants in ribosomal proteins would likely impact on ribosome function and translation efficiency, live/dead screening on LB agar would be effective as a preliminary screen for functional mutants. These mutants would subsequently be inoculated into liquid LB medium in 96 well plates to quantify relative growth rates between different strains harbouring different heterologous variants of ribosomal proteins. Plasmids containing different ribosomal protein mutants would be extracted from each functional strain and subjected to Sanger sequencing for determining the specific mutations involved. Collection of such mutations would provide a comprehensive mutational map that define the limits of ribosomal protein sequence space important to ribosome function. Furthermore, biochemical isolation of ribosomal proteins and their structural characterization by X-ray crystallography or cryo-electron microscopy would further illuminate the structural significance of each mutation on ribosome structure and function; thereby, elucidating the structural tolerance space for functional ribosomes. Overall, generating a diverse pool of mutant ribosomal proteins in viability assays followed by sequencing and structural characterization would help define the mutational and conformational limits of a functional and efficient ribosome.