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Life Sciences, Biochemistry; Nuclear Magnetic Resonance Spectroscopy, Metabolomics, Biomarker, Random Forest.
Online: 1 August 2018 (11:30:39 CEST)
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Background: Diabetes is among the most prevalent diseases worldwide, of all the affected individuals a significant proportion of the population remains undiagnosed because of a lack of specific symptoms early in this disorder and inadequate diagnostics. Diabetes and its associated sequela, i.e., comorbidity are associated with microvascular and macrovascular complications. As diabetes is characterized by an altered metabolism of key metabolites and regulatory pathways. Metabolic phenotyping can provide us with a better understanding of the unique set of regulatory perturbations that predispose to diabetes and its associated comorbidities.
Methodology: The present study utilizes the analytical platform NMR spectroscopy coupled with Random Forest statistical analysis to identify the discriminatory metabolites of diabetes (DB) and diabetes-related comorbidity (DC) along with the healthy control (HC) subjects. A combined and pairwise analysis was performed, between the serum samples of HC (n=50), and DB (n=38), and DC (n=35) individuals to identify the discriminatory metabolites responsible for class separation. The perturbed metabolites were further rigorously validated using t-test, AUROC analysis to examine the statistical significance of the identified metabolites.
Results: The DB and DC patients were well discriminated from HC. However, 15 metabolites were found to be significantly perturbed in DC patients compared to DB, the identified panel of metabolites are TCA cycle (succinate, citrate), methylamine metabolism (trimethylamine, methylamine, betaine), -intermediates; energy metabolites (glucose, lactate, pyruvate); and amino acids (valine, arginine, glutamate, methionine, proline and threonine). The metabolites were further used to identify the perturbed metabolic pathway and correlation of metabolites in DC patients.
Conclusion: The 1H NMR metabolomics may prove a promising technique to differentiate and predict diabetes and its comorbidities on their onset or progression by determining the altered levels of the metabolites in serum.
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Life Sciences, Biochemistry; PhaC synthase; classification; dimerization; substrate binding; exit cavity; C3-C14 alkanes; polymer composition
Online: 26 July 2018 (12:03:44 CEST)
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PHA synthases (PhaC) are grouped into four classes based on the kinetics and mechanisms of reaction. The grouping of PhaC enzymes into four classes is dependent on substrate specificity, according to the preference in forming short chain length (scl) or medium chain length (mcl) polymers: class I, class III, and class IV produce scl-PHAs depending on propionate, butyrate, valerate and hexanoate precursors, while class II phaC synthesize mcl-PHAs based on the alkane (C6 to C14) precursors. PHA synthases of class I, in particular PhaCCs from Chromobacterium USM2 and PhaCCn/RePhaC1 from Cupriavidus necator/R. eutropha, have been analysed and the crystal structures of the C-domains have been determined. PhaCCn/RePhaC1 was also studied by small angle X-ray scattering (SAXS) analysis. Models have been proposed for dimerization, catalysis mechanism, substrate recognition and affinity, product formation and product egress route. The assays based on amino acid substitution by mutagenesis have been useful to validate the hypothesis on the role of amino acids in catalysis and in accommodation of bulky substrates, for the synthesis of PHB co-polymers and medium chain length-PHA polymers with optimized chemical properties.
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Life Sciences, Biochemistry; Carica papaya; fermented papaya preparation (FPP); free radical scavenging; antioxidant; oxidative stress; anti-diabetic; anti-carcinogenic
Online: 24 July 2018 (11:39:50 CEST)
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The simplistic morphological characteristics of the Carica papaya, papaya or ‘pawpaw’ should not be the cause for underestimating its potential as a nutraceutical. The market for papaya has been expanding at a staggering rate, partly due to its applicability as a biofortified product, but mostly for its phytochemical properties and traditional health benefits. Recent characterization studies have showed that the entirety of papaya or using a formulation of fermented papaya promotion (FPP) displays effective free radical scavenging abilities, thought to be influenced by its phenolic, carotenoids, flavonoid or amino acid profile. Aiming at reducing the impact of free radical-induced oxidative damage in the human system, the antioxidant properties of FPP have been found to potently target a broad spectrum of diseases ranging from neurological impairments such as senile dementia to systemic diseases, to its interference at the cellular level and support of normal biological ageing processes. FPP has thus been extensively investigated for its ability to exert cellular protective effects and reduce oxidative stress via mitigation of genetic damage, lipid peroxidation and enzymatic inactivation in diseases. Oxidative stress reduction strategies using FPP and its holistic approach in disease prevention and management, with a focus on diabetes, cancer and cognitive health, contributes unequivocally to wellness in an aging population.
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Life Sciences, Biochemistry; genetic code expansion, protein kinase B, phosphoinositide dependent kinase 1 (PDK1), phosphoseryl-tRNA synthetase (SepRS), tRNASep
Online: 21 July 2018 (12:35:26 CEST)
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Akt1 is a proto-oncogene that is over active in most cancers. Akt1 activation requires phosphorylation at Thr308; phosphorylation at Ser473 further enhances catalytic activity. Akt1 activity is also regulated via interactions between the kinase domain and the N-terminal auto-inhibitory pleckstrin homology (PH) domain. As it was previously difficult to produce Akt1 in site-specifically phosphorylated forms, the contribution of each activating phosphorylation site to auto-inhibition was unknown. Using a combination of genetic code expansion and in vivo enzymatic phosphorylation, we produced Akt1 variants containing programmed phosphorylation to probe the interplay between Akt1 phosphorylation status and the auto-inhibitory function of the PH domain. Deletion of the PH domain increased the enzyme activity for all three phosphorylated Akt1 variants. For the doubly phosphorylated enzyme, deletion of the PH domain relieved auto-inhibition by 295-fold. We next found that phosphorylation at Ser473 provided resistance to chemical inhibition by Akti-1/2 inhibitor VIII. The Akti-1/2 inhibitor was most effective against pAkt1T308 and showed 4-fold decreased potency with Akt1 variants phosphorylated at Ser473. The data highlight the need to design more potent Akt1 inhibitors that are effective against the doubly phosphorylated and most pathogenic form of Akt1.
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Life Sciences, Biochemistry; hepcidin-25; copper; nickel; ATCUN motif; metal complex; MS; NMR structure; metal peptide, metalloprotein; metallopeptide, isomerization, racemization, purity, reference material
Online: 14 June 2018 (11:33:21 CEST)
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Hepcidin-25 was identified as the main iron regulator in the human body by binding to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II)-binding site known as ATCUN (amino terminal Cu(II)- and Ni(II)- binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the formed complex of hepcidin-25 with copper could reveal insights into its biological role. The present work is mainly focused on the study of the metal-bound form of hepcidin-25, which could be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25, which was achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandem mass spectrometry MS/MS, high resolution mass spectrometry HRMS) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a 3D model of hepcidin-25 with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or reference material comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others.
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Life Sciences, Biochemistry; Trypanosoma cruzi; benznidazole; resistance; quantum mechanics; molecular mechanics
Online: 1 June 2018 (10:22:17 CEST)
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The Chagas disease (CD) is an endemic infectious disease in a large part of Latin America. This disease is characterized by the fact of being caused by the parasite Trypanosoma cruzi. Some symptoms of this disease are cardiopathies and gastrointestinal problems. Therefore, the commonly used treatment consists of nitro drugs such as benznidazole and nifurtimox, which target the nitroreductase enzyme that docks to the coenzyme flavin mononucleotide (FMN) and an oxidation-reduction reaction is generated. From this reaction, the nitro chemical function of benznidazole and nifurtimox is reduced to amine. This amine in turn interacts with the parasite´s DNA. In vitro tests experimentally help in the study of the parasite resistance to the drug benznidazole. This fact could explain how nonsynonymous mutations in the nitroreductase (NTR) enzyme do not allow the anchorage of the FMN coenzyme and as a consequence the parasite susceptibility to benznidazole decreases as the drug cannot be reduced. The structural relations from the hybrid Quantum Mechanics-Molecular Mechanics (QM/MM) allow to detect the small changes generated in the system, considering a charge distribution associated with the structure, angle changes, interaction distances, potential surface calculations between the wildtype enzyme and the mutation found.
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Life Sciences, Biochemistry; LC-QQQ; liquid chromatography; triple quadrupole; vitamin D; 25(OH)D; plants; algae
Online: 24 May 2018 (09:27:21 CEST)
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Vitamin D has previously been quantified in some plants and algae, particularly in leaves of the Solanaceae family. We measured the vitamin D content of Australian native food plants and Australian-grown edible seaweed. Using liquid chromatography with triple quadrupole mass spectrometry, 13 samples (including leaf, fruit and seed) were analysed in duplicate for vitamin D2, vitamin D3, 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3. Five samples contained vitamin D2: raw wattleseed (Acacia victoriae) (0.03 µg/100 g dry weight (DW)); fresh and dried lemon myrtle (Backhousia citriodora) leaves (0.03 and 0.24 µg/100 g DW, respectively); dried leaves and berries of Tasmanian mountain pepper (Tasmannia lanceolata) (0.67 and 0.05 µg/100 g DW, respectively). Fresh kombu (Lessonia corrugata) contained vitamin D3 (0.01 µg/100 g DW). Detected amounts were low; however, it is possible that exposure to ultraviolet radiation may increase the vitamin D content of plants and algae if vitamin D precursors are present.
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Life Sciences, Biochemistry; carbonic anhydrase, enzyme inhibition, metalloenzymes, amino acid, glaucoma, tumors
Online: 9 May 2018 (13:55:15 CEST)
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Carbonic Anhydrases (CAs) are a superfamily of metalloenzymes widespread in all life kingdoms, classified into seven genetically different families (α-θ). These enzymes catalyse the reversible hydration of carbonic anhydride (CO2), generating bicarbonate (HCO3-) and protons (H+). Fifteen isoforms of human CA (hCA I-XV) have been isolated, their presence being fundamental for the regulation of many physiological processes. In addition, overexpression of some isoforms has been associated with the outbreak or the progression of several diseases. For this reason, for a long time CA inhibitors (CAIs) are used in the control of glaucoma and as diuretics. Furthermore, the search for new potential CAIs for other pharmacological applications is a very active field. Amino acids constitute the smallest fundamental monomers of protein and, due to their useful bivalent chemical properties, are widely used in organic chemistry. Both proteinogenic and non-proteinogenic amino acids have been extensively used to synthesize CAIs. This article provides an overview of the different strategies that have been used to design new CAIs containing amino acids, and how these bivalent molecules influence the properties of the inhibitors.
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Life Sciences, Biochemistry; Non-small cell lung cancer; Lambertianic acid; Apoptosis; TRAIL; XIAP; NF-B
Online: 18 April 2018 (15:25:10 CEST)
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Lambertianic acid (LA) is a biologically active compound from the leaves of Pinus koraiensis. In the present study, apoptotic mechanisms of LA plus TNF-related apoptosis-inducing ligand (TRAIL) were elucidated in non-small cell lung cancer cells (NSCLCs). Cytotoxicity assay, flow cytometry, immunoprecipitation and Western blotting were performed. Here, combined treatment of LA and TRAIL increased cytotoxicity, sub-G1 population and cleaved poly (ADP-ribose) polymerase (PARP) and caspase3/8/9 in A549 and H1299 cells compared to LA or TRAIL alone. Furthermore, combined treatment of LA and TRAIL significantly decreased anti-apoptotic proteins such as B-cell lymphoma 2 (Bcl-2), Fas-like inhibitor protein (FLIP) and X-linked inhibitor of apoptosis protein (XIAP) and enhanced the activation of pro-apoptotic proteins Bid compared to LA or TRAIL alone. In addition, combined treatment of LA and TRAIL upregulated the expression of Death receptor 4 (DR4) and downregulated phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells (p-NF-B), inhibitory protein of kB family (p-IB) and FLIP in A549 and H1299 cells along with disrupted binding of XIAP with caspase3 or NF-B. Overall, these findings suggest that lambertianic acid enhances TRAIL-induced apoptosis via inhibition of XIAP/NF-B in TRAIL resistant NSCLCs.
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Life Sciences, Biochemistry; axon guidance; DRS; HGPPS; CFEOM3; in silico; systems biology; PPI network
Online: 18 April 2018 (08:23:58 CEST)
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Axon guidance is a crucial process for growth of the central and peripheral nervous systems. In this study, 3 axon guidance related disorders, namely- Duane Retraction Syndrome (DRS) , Horizontal Gaze Palsy with Progressive Scoliosis (HGPPS) and Congenital fibrosis of the extraocular muscles type 3 (CFEOM3) were studied using various Systems Biology tools to identify the genes and proteins involved with them to get a better idea about the underlying molecular mechanisms including the regulatory mechanisms. Based on the analyses carried out, 7 significant modules have been identified from the PPI network. Five pathways/processes have been found to be significantly associated with DRS, HGPPS and CFEOM3 associated genes. From the PPI network, 3 have been identified as hub proteins- DRD2, UBC and CUL3.
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Life Sciences, Biochemistry; connexins; gap junctions; transcription; translation; post-translational modifications; trafficking
Online: 20 March 2018 (05:27:38 CET)
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Connexins are tetraspan transmembrane proteins that form gap junctions and facilitate direct intercellular communication, a critical feature for the development, function and homeostasis of tissues and organs. In addition, a growing number of gap junction-independent functions are being ascribed to these proteins. The connexin gene family is under extensive regulation at the transcriptional and post-transcriptional level, and undergoes numerous modifications at the protein level, including phosphorylation, which ultimately affects their trafficking, stability and function. Here, we summarize these key regulatory events, with emphasis on how these affect their multi-functionality in health and disease.
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Life Sciences, Biochemistry; Alzheimer disease; Amyloid β-protein; Antibodies; Cross-reactions; Nucleotide aptamers; Oligonucleotide ligands; Systematic evolution of ligands by exponential enrichment; Specificity; Therapeutics
Online: 5 February 2018 (22:37:02 CET)
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Aptamers are versatile oligonucleotide ligands used for molecular recognition of diverse targets. However, application of aptamers to the field of amyloid β-protein (Aβ) has been limited so far. Aβ is an intrinsically disordered protein that exists in a dynamic conformational equilibrium, presenting time-dependent ensembles of short-lived, metastable structures and assemblies that have been generally difficult to isolate and characterize. Moreover, despite understanding of potential physiological roles of Aβ, this peptide has been linked to the pathogenesis of Alzheimer disease, and its pathogenic roles remain controversial. Accumulated scientific evidence thus far highlights undesirable or nonspecific interactions between selected aptamers and different Aβ assemblies likely due to metastable nature of Aβ or inherent affinity of RNA oligonucleotides to β-sheet-rich fibrillar structures of amyloidogenic proteins. Accordingly, lessons drawn from Aβ–aptamer studies emphasize that purity and uniformity of the protein target and rigorous characterization of aptamers’ specificity are important for realizing and garnering the full potential of aptamers selected for recongizing Aβ or other intrinsically disordered proteins. This review summarizes studies of aptamers selected for recognizing different Aβ assemblies and highlights controversies, difficulties, and limitations of such studies.
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Life Sciences, Biochemistry; sulfoxidation; epoxidation; two-component monooxygenase; flavoprotein; enantioselective biotransformation; fusion protein; protein linker; soil microorganism
Online: 25 January 2018 (17:14:33 CET)
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VpStyA1 and VpStyA2B of Variovorax paradoxus EPS is annotated and characterized as the first representative of an E2-type styrene monooxygenase of proteobacteria. It comprises a single epoxidase (VpStyA1) and a fusion protein (VpStyA2B) which serves mainly as NADH:FAD-oxidoreductase. VpStyA2B had a Km of 33.6 ± 4.0 µM for FAD and a kcat of 22.3 ± 1.1 s-1. VpStyA2B and VpStyA1 showed monooxygenase activity on styrene of 0.14 U mg-1 and 0.46 U mg-1 as well as on benzyl methyl sulfide of 1.62 U mg-1 and of 3.11 U mg-1. A putative fusion region at position 408 (AREAV) was mutated to provide insights on VpStyA2B-function. The best mutant (408-AAAAA) obtained showed a 6.6-times higher affinity for FAD while keeping the NADH-affinity and -oxidation activity. Corresponding epoxidase activity increased (1.6-times). But, other mutants showed still NADH:FAD-oxidoreductase activity, but lost mostly their epoxidase activity indicating effects on the monooxygenase-part as well. Thus, this monooxygenase system represents an interesting candidate for biocatalyst development.
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Life Sciences, Biochemistry; DCP-LA; PKCε; protein tyrosine phosphatase 1B; Akt; GSK-3β; tauopathy
Online: 17 January 2018 (05:26:21 CET)
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Abnormal Tau phosphorylation and aggregation into neuronal paired helical filaments and neurofibrillary tangles cause tauopathies, a class of neurodegenerative diseases, that include Alzheimer’s disease, frontotemporal dementia and parkinsonism linked to chromosome 17, progressive supranuclear palsy, Pick's disease, and corticobasal degeneration. Glycogen synthase kinase-3β (GSK-3β) is the most critical kinase to phosphorylate Tau. We have developed the linoleic acid derivative 8-[2-(2-pentyl-cyclopropylmethyl)-cyclopropyl]-octanoic acid (DCP-LA), with cyclopropane rings instead of cis-double bonds, as an anti-dementia drug. DCP-LA serves as a selective activator of PKCε and a potent inhibitor of protein tyrosine phosphatase 1B (PTP1B). DCP-LA prevents Tau phosphorylation due to PKCε-mediated direct inactivation of GSK-3β, to PKCε/Akt-mediated inactivation of GSK-3β, and to receptor tyrosine kinase-mediated inactivation of GSK-3β in association with PTP1B inhibition. DCP-LA targeting GSK-3β, thus, could become a valid drug for treatment of tauopathies.
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Life Sciences, Biochemistry; graphene; electrochemical biosensors; cancer; diagnosis; electrical detection; Alzheimer’s disease; dementia; neurodegenerative disorders; cardiovascular; blood biomarkers; antibodies; proteins
Online: 2 January 2018 (05:21:45 CET)
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We report on the development of chemical vapour deposition (CVD) based graphene field effect transistor (GFET) immunosensors for the sensitive detection of Human Chorionic Gonadotropin (hCG), a glycoprotein risk biomarker of certain cancers. The GFET sensors were fabricated on Si/SiO2 substrate using photolithography with evaporated chromium and sputtered gold contacts. GFET channels were functionalized with a linker molecule to immobile anti-hCG antibody on the surface of graphene. Binding reaction of the antibody with varying concentration levels of hCG antigen demonstrated the limit of detection of the GFET sensors to be below 1 pg/mL using four-probe electrical measurements. We also show annealing can significantly improve the carrier transport properties of GFETs and shift the Dirac point (Fermi level) with reduced p-doping in back-gated measurements. The developed GFET biosensors are generic and could find applications in a broad range of medical diagnostics in addition to cancer, such as neurodegenerative (Alzheimer’s, Parkinson’s and Lewy body) and cardiovascular disorders.
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Life Sciences, Biochemistry; purple sweetpotato; anthocyanin; polyphenolics; caffeoylquinic acid; temperature
Online: 25 December 2017 (10:01:14 CET)
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The health benefits of purple sweetpotato, which is used as an edible food in its natural state and in processed foods and as a natural color pigment, have been recognized. In Japan, sweetpotato has been economically produced in regions below 36°4′N latitude, however, cultivation areas are beginning to expand further north. The anthocyanin and polyphenolics in purple sweetpotatoes cultivated in different locations; I (42°92′ N, 143°04′ E), II (35°99′ N, 140°01′ E), and III (31°72′ N, 131°03′ E), were compared over two years. Total anthocyanin and polyphenolic contents in purple sweetpotatoes tended to be high in location I. Their contents significantly differed over the two years in locations I and III and was dependent on temperature during cultivation. The anthocyanin and polyphenolic compositions differed between locations. The peonidin/cyanidin ratios were higher in location III compared with I and II in all varieties. The relative amount of chlorogenic acid was higher in location I, while the amount of 3,4- and 4,5-dicaffeoyolquinic acids were higher in location III, suggesting that the variability of the anthocyanin and polyphenolic content and composition was dependent on cultivation conditions. This study suggested that northern areas in Japan are an alternative production area and may yield higher amounts of anthocyanin and polyphenolics.
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Life Sciences, Biochemistry; epigenome; DNA modification; cytosine methylation; gene regulation; histone modification; 5-methylcytosine; stress response
Online: 25 December 2017 (09:43:03 CET)
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Genome-wide epigenetic changes in plants are being reported during the development and environmental stresses, which are often correlated with gene expression at the transcriptional level. Sum total of the biochemical changes in nuclear DNA, post-translational modifications in histone proteins and variations in the biogenesis of non-coding RNAs in a cell is known as epigenome. These changes are often responsible for variation in expression of the gene without any change in the underlying nucleotide sequence. The changes might also cause variation in chromatin structure resulting into the changes in function/activity of the genome. The epigenomic changes are dynamic with respect to the endogenous and/or environmental stimuli which affect phenotypic plasticity of the organism. Both, the epigenetic changes and variation in gene expression might return to the pre-stress state soon after withdrawal of the stress. However, a part of the epigenetic changes may be retained which is reported to play role in acclimatization, adaptation as well as in the evolutionary processes. Understanding epigenome-engineering for improved stress tolerance in plants has become essential for better utilization of the genetic factors. This review delineates the importance of epigenomics towards possible improvement of plant’s responses to environmental stresses for climate resilient agriculture.
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Life Sciences, Biochemistry; algae; Euglena; biotechnology; carbohydrates; N-glycan; sugar nucleotide
Online: 17 December 2017 (08:55:09 CET)
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Euglena gracilis is an alga of great biotechnological interest and extensive metabolic capacity, able to make high levels of bioactive compounds, such as polyunsaturated fatty acids, vitamins and β-glucan. Previous work has shown that Euglena expresses a wide range of carbohydrate-active enzymes, suggesting an unexpectedly high capacity for the synthesis of complex carbohydrates for a single-celled organism. Here, we present an analysis of some of the carbohydrates synthesised by Euglena gracilis. Analysis of the sugar nucleotide pool showed that there are the substrates necessary for synthesis of complex polysaccharides, including the unusual sugar galactofuranose. Lectin- and antibody-based profiling of whole cells and extracted carbohydrates revealed a complex galactan, xylan and aminosugar based surface. Protein N-glycan profiling, however, indicated that just simple high mannose-type glycans are present and that they are partially modified with putative aminoethylphosphonate moieties. Together, these data indicate that Euglena possesses a complex glycan surface, unrelated to plant cell walls, while its protein glycosylation is simple. Taken together, these findings suggest that Euglena gracilis may lend itself to the production of pharmaceutical glycoproteins.
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Life Sciences, Biochemistry; Bryopsis plumosa; BPL3; lectin; hemagglutinin; recombinant; tandem repeat; GlcNAc; GalNAc
Online: 28 November 2017 (07:20:39 CET)
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Lectins, characterized by their carbohydrate-binding ability, have an extensive practical application. However, their industrial use is limited by low yields, and few active recombinant lectins have been reported. In this study, the algal lectin BPL-3 (Bryopsis plumosa lectin 3) was successfully produced using a bacterial expression system, BL21(DE3), with an artificial repeated structure (dimeric construct). Recombinant dimeric BPL3 (rD2BPL3) was confirmed by LC-MS/MS spectrometry. Expression efficiency was greater for the construct with the repeat structure (rD2BPL3) than the monomeric form (rD1BPL3). Optimal conditions for expression were 1 mM IPTG at 20 °C. Recombinant lectin was purified under denaturing conditions and refolded by the flash dilution method. Recombinant BPL3 was solubilized in 1× PBS containing 2 M urea. rD2BPL3 showed strong hemagglutination activity using human erythrocytes, similar to that of native BPL3. rD2BPL3 had a similar sugar specificity to that of the native protein, i.e., to N-acetyl-glucosamine (GlcNAc) and N-acetyl-galactosamine (GalNAc). Glycan array results showed that recombinant BPL3 and native BPL3 exhibited different binding properties. Both showed weak binding activity to α-Man-Sp. Native BPL3 showed strong binding specificity to the alpha conformation of amino sugars, and rD2BPL3 had binding activity to the beta conformation. The process developed in this study was suitable for the quality-controlled production of high amounts of soluble recombinant lectins.
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Life Sciences, Biochemistry; false discovery rate; machine learning; protein function prediction; support vector machine; BLAST
Online: 24 November 2017 (11:14:05 CET)
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The knowledge of protein function is essential for the study of biological processes, the understanding of disease mechanism and the exploration of novel therapeutic target. Apart from experimental methods, a number of in-silico approaches have been developed and extensively used for protein function prediction. Among these approaches, BLAST predicts functions based on protein sequence similarity, and machine learning predicts functional families from protein sequences irrespective of their similarity, which complements BLAST and other methods in predicting diverse classes of proteins including distantly related proteins and homologous proteins of different functions. However, their identification accuracies and the false discovery rate have not yet been assessed so far, which greatly limits the usage of these prediction algorithms. Herein, a comprehensive comparison of the performances among four popular functional prediction algorithms (BLAST, SVM, PNN and KNN) was conducted. In particular, the performance of these algorithms were systematically assessed by four metrics (sensitivity, specificity, accuracy and Matthews correlation coefficient) based on the independent test datasets generated from 93 protein families defined by UniProtKB Keywords. Moreover, the false discovery rates of these algorithms were evaluated by scanning the genomes of four representative model species (homo sapiens, arabidopsis thaliana, saccharomyces cerevisiae and mycobacterium tuberculosis). As a result, the substantially higher sensitivity and stability of BLAST and SVM were observed compared with that of PNN and KNN. But the machine learning algorithms (PNN, KNN and SVM) were found capable of significantly reducing the false discovery rate (SVM < PNN ≈ KNN). In summary, this study comprehensively assessed the performance of four popular algorithms applied to protein function prediction, which could facilitate the selection of the most appropriate method in the related biomedical research.
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Life Sciences, Biochemistry; ncRNAs; ovarian cancer; chemoresistance
Online: 4 October 2017 (11:59:09 CEST)
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With the advancement of next generation sequencing in past several years, a rising number of non-coding RNAs have been found as new actors to regulate gene expression. Non-coding RNAs not only play important roles in carcinogenesis, but also affect the clinical treatment strategies. They have been proved to be deeply correlated with chemoresistance in several cancers. Ovarian cancer is the leading cause of death in gynecological malignancy, with low 5-year survival rate. Most patients are identified when they have late-stage disease. This review mainly makes a compilation of the most relevant research literature in this field with the purpose of shedding light on the relation between ncRNAs and chemoresistance in ovarian cancer.
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Life Sciences, Biochemistry; omega-3; PUFA; chemoresistance; membrane; DHA; EPA
Online: 29 September 2017 (18:32:40 CEST)
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The efficacy of chemotherapy depends on sensitivity and intrinsic or acquired drug resistance of cancer cells. The n-3 long chain polyunsaturated fatty acids (n-3 LCPUFAs) are considered chemosensitizing agents and revertants of multidrug resistance by pleiotropic mechanisms. The specific mechanisms are not fully understood, but nowadays, it is widely accepted that there are a complex network of mechanisms, including alteration in gene expression, modulation of cellular proliferation and differentiation, induction of apoptosis, generation of reactive oxygen species and lipid peroxidation. A crucial mechanism in the control of cell drug uptake and efflux is related to n-3 LCPUFA influence on membrane lipid composition. The incorporation of docosahexaenoic acid in the lipid rafts produces significant changes in their physical-chemical properties affecting content and functions of transmembrane proteins, such as growth factors, receptors and ATP-binding cassette transporters. Of note, n-3 LCPUFAs often impact on the lipid compositions more in chemoresistant cells than in chemosensitive cells, suggesting their adjuvant role in cancer treatment.
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Life Sciences, Biochemistry; MAPLE; Matrix Assisted Pulsed Laser Evaporation; microemulsion; lipase; thin film
Online: 21 September 2017 (17:10:01 CEST)
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MAPLE (matrix assisted pulsed laser evaporation) depositions of Candida Rugosa lipase were carried out from ice matrices whose composition is optimized in order to minimize conformational damage of the protein, which strongly influences its catalytic activity. To induce lid opening and to protect lipase during the MAPLE process, pentane and m-DOPA amino acid were added to the liquid matrix giving a target formed by a frozen water-lipase-pentane microemulsion. FTIR and AFM were used to investigate the structure of MAPLE deposited lipase films. The ability of MAPLE films to promote transesterification was determined by thin layer chromatography. It was shown that m-DOPA has influence on the aggregation but not on the unfolding of lipase induced by MAPLE, while the microemulsion formed by the addition of pentane to the target composition is effective in protecting lipase during the MAPLE process. MAPLE deposited lipases showed a modified specificity.
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Life Sciences, Biochemistry; Glyoxalases; urological malignancies; prostate cancer; kidney cancer; bladder cancer testicular cancer
Online: 15 September 2017 (14:28:24 CEST)
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Urological cancers include a spectrum of malignancies affecting organs of the reproductive and/or urinary systems, such as prostate, kidney, bladder, and testis. Despite improved primary prevention, detection and treatment, urological cancers are still characterized by an increasing incidence and mortality worldwide and although advances have been made toward understanding the molecular basis of these diseases, a complete insight of the pathogenic mechanisms is still a research challenge for defining safer pharmacological therapies and prognostic factors, especially for the metastatic stage of these neoplasms for which no effective therapies exist. Glyoxalases are enzymes that catalyzes the glutathione-dependent metabolism of cytotoxic methylglyoxal (MG), thus protecting against cellular damage and apoptosis. They are generally overexpressed in numerous cancers as a survival strategy by providing a safeguard through enhancement of MG detoxification. Increasing evidence suggest that glyoxalases, especially Glo1, would act as oncogenes in urological malignancies and be central to their initiation, growth and progression. In this review, we highlight the critical role of glyoxalases as regulators of tumorigenesis in the prostate through modulation of various critical signaling pathways, and provide an overview of the current knowledge on glyoxalases in bladder, kidney and testis cancers. We also discuss the promise and challenges for Glo1 inhibitors as future anti-PCa therapeutics and the potential of glyoxalases as biomarkers for PCa diagnosis.
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Life Sciences, Biochemistry; insulin; phenolic derivatives; crystallography; powder diffraction
Online: 12 July 2017 (04:11:12 CEST)
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Human Insulin (HI) is a well-characterized natural hormone which regulates glycose levels into the blood-stream and is widely used for diabetes treatment. Numerous studies have manifested that despite significant efforts devoted to structural characterization of this molecule and its complexes with organic compounds (ligands), there is still a rich diagram of phase transitions and novel crystalline forms to be discovered. Towards the improvement of drug delivery, identification of new insulin polymorphs from polycrystalline samples, simulating the commercially available drugs, is feasible today via macromolecular X- ray powder diffraction (XRPD). This approach has been developed and is considered as a respectable method, which can be employed in biosciences for various purposes such as observing phase transitions and characterizing bulk pharmaceuticals. An overview of structural studies on human insulin complexes performed over the past decade employing both synchrotron and laboratory sources for XRPD measurements, is reported herein. This review aims to assemble all recent advances in diabetes treatment field in terms of drug formulation, verifying in parallel the efficiency and applicability of protein XRPD for quick and accurate preliminary structural characterization in large scale.
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Life Sciences, Biochemistry; DNA polymerase δ; PDIP46; poldip3; PDIP38; poldip2; DNA replication; enzyme regulation; DNA damage response; p12 subunit; E3 ligases; cell cycle
Online: 10 July 2017 (08:44:53 CEST)
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This review focuses on the regulation and modulation of human DNA polymerase δ (Pol δ). The emphasis is on mechanisms that regulate the activity and properties of Pol δ in DNA repair and replication. The areas covered are the degradation of the p12 subunit of Pol δ, which converts it from a heterotetramer (Pol δ4) to a heterotrimer (Pol δ3), in response to DNA damage and also during the cell cycle. The biochemical mechanisms that lead to degradation of p12 are reviewed, as well as the properties of Pol δ4 and Pol δ3 that provide insights into their functions in DNA replication and repair. The second focus of the review involves the functions of two Pol δ binding proteins, PDIP46 and PDIP38, both of which are multi-functional proteins. PDIP46 is a novel activator of Pol δ4, and the impact of this function is discussed in relation to its potential roles in DNA replication. Several new models for the roles of Pol δ3 and Pol δ4 in leading and lagging strand DNA synthesis that integrate a role for PDIP46 are presented. PDIP38 has multiple cellular localizations including the mitochondria, the splicesosomes and the nucleus. It has been implicated in a number of cellular functions, including the regulation of specialized DNA polymerases, mitosis, the DNA damage response, Mdm2 alternative splicing and the regulation of the Nox4 NADPH oxidase.
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Life Sciences, Biochemistry; flavonoids; nitric oxide (•NO); nitrosation; nitrous acid; quinones; redox reactions; stomach; thiocyanic acid.
Online: 28 June 2017 (07:41:14 CEST)
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Foods are mixed with saliva in the oral cavity and swallowed. During staying in the stomach, saliva is contentiously provided to mix with the ingested foods. Because a salivary component nitrite is protonated to produce active nitrous acid at acidic pH, the redox reactions of nitrous acid with phenolic compounds in foods become possible in the stomach. In the reactions, nitrous acid is reduced to nitric oxide (•NO), producing various products from phenolic compounds. In the products, stable hydroxybezoyl benzofuranone derivatives, which are produced from quercetin and its 7-O-glucoside, are included. Caffeic acid, chlorogenic acid, and rutin are oxidized to quinones and the quinones can react with thiocyanic acid derived from saliva producing stable oxathiolone derivatives. 6,8-Dinitrosocatechis are produced from catechins by the redox reaction, and the dinitrocatechins are oxidized further by nitrous acid producing the quinones, which can make charge transfer complexes with the dinitrosocatechin and can react with thiocyanic acid producing the stable thiocyanate conjugates. In this way, various products can be produced by the reactions of salivary nitrite with dietary phenolic compounds, and reactive and toxic quinones formed by the reactions are postulated to be removed in the stomach by thiocyanic acid derived from saliva.
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Life Sciences, Biochemistry; proteins；time-varying； parallel； architectures；Conditional Random Fields (CRF)；Graphics Processing Units； Block Coordinate Descent algorithm
Online: 26 June 2017 (05:47:40 CEST)
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Proteins are the workhorses of the cell that perform biological functions by interacting with other proteins. Many statistical methods for protein-protein interaction (PPI) have been studied without considering time-dependent changes in networks and the functionalities. I introduced a novel method that models PPI networks as being dynamic in nature and evolving time-varying multivariate distribution with Conditional Random Fields (CRF). This research is directed towards implementing this new combinatorial algorithm on massively parallel architectures such as Graphics Processing Units (GPUs) for efficient computations for large scale bioinformatics datasets. I compared Conditional Random Fields (CRF) and the proposed novel method using CRF combined with the Block Coordinate Descent algorithm for human protein-protein interaction data set. Both are implemented on GPU-Accelerated Computing Architecture and the proposed novel method showed the advantages in predicting protein-protein interaction sites. I also show that the proposed approach is more efficient in 6.13% than standalone CRF++ in predicting protein-protein interaction sites.
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Life Sciences, Biochemistry; 8-prenylnaringenin; naringenin; cellular accumulation; glioblastoma; cytotoxicity; confocal microscopy
Online: 16 June 2017 (03:25:34 CEST)
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Gliomas are one of the most aggressive and treatment-resistant types of human cancer. One of the most promising field in gliomas cancer therapy is identification and evaluation of anticancer properties of compounds found in plants i.a. naringenin (N) and 8-prenylnaringenin (8PN). The prenyl group seem to be crucial to the anticancer activity of flavones, which may lead to enhanced cell membrane targeting and thus increased intracellular activity. Unfortunately, 8PN content in hop cones is from 10 to 100 times lower compared to other flavonoids i.e. xanthohumol. In this study we used a simple method for the synthesis of 8PN from isoxanthohumol, via O-demethylation with high, 97% of the isolated yield. Cellular accumulation and cytotoxicity of naringenin and 8-prenylnaringenin in normal (BJ) and cancer cells (U-118 MG) were also examined. Obtained data indicated that 8-prenylnaringenin exhibited higher toxicity against used cell lines than naringenin and both flavones inhibited stronger glioblastoma U-118 MG cells than normal fibroblasts. The anticancer properties of 8PN correlated with its significantly greater (37%), accumulation in glioblastoma cells than in normal fibroblasts. Additionally, naringenin indicated higher selectivity for glioblastoma as it was over 6 times more toxic for cancer than normal cells. Our results provide evidence that examined prenylated and non-prenylated flavanones have different biological activity against normal and cancer cell lines and this phenomenon may be useful in clinical practice to construct new, anticancer drugs for glioblastoma.
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Life Sciences, Biochemistry; loureirin B; Ins-1 cells; Insulin secretion; KATP channel; influx of Ca2+; expression of Cx43
Online: 26 May 2017 (04:52:12 CEST)
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The development of new diabetes drugs continues to be explored. Loureirin B, a flavonoid, extracted from Dracaena cochinchinensis, has been confirmed to increase insulin secretion and decrease blood glucose levels. For understanding the mechanism, a series of experiments had been employed based on computational methods and cell experiments. The insulin secretion significantly increased with the incubation of 0.01μM loureirin B for 4 hours. The viability of Ins-1 cells showed no significant difference with the treatment of loureirin B. Through computational methods, we hypothesized that loureirin B could interacts with KATP channels to promote insulin secretion. In cell experiments, it could be found that the current of KATP channel of Ins-1 cells was inhibited by the effect of loureirin B. After then, the voltage-dependent calcium channels were activated, the increase of Cx43 protein expression might mediate the Ca2+ to the intracellular. In summary, it could be concluded that loureirin B promoted insulin secretion mainly through inhibiting KATP current, the influx of Ca2+ to the Intracellular and the expression of Cx43.
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Life Sciences, Biochemistry; Cholangiocarcinoma; DNA methylation; Tumor suppressor gene; microRNA; DNA methylation inhibitor
Online: 16 May 2017 (18:08:59 CEST)
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Cholangiocarcinoma is an epithelial malignancy arising in the region between the intrahepatic bile ducts and the ampulla of Vater at the distal end of the common bile duct. The effect of current chemotherapy regimens against cholangiocarcinoma is limited, and the prognosis of patients with cholangiocarcinoma is poor. Aberrant DNA methylation and histone modification induce silencing of tumor suppressor genes and chromosomal instability during carcinogenesis. Studies have shown that the tumor suppressor genes and microRNAs (miRNAs) including MLH1, p14, p16, DAPK, miR-370 and miR-376c are frequently methylated in cholangiocarcinoma. Silencing of these tumor suppressor genes and miRNAs plays critical roles in the initiation and progression of cholangiocarcinoma. In addition, recent studies have demonstrated that DNA methylation inhibitors induce expression of endogenous retroviruses and exert the anti-tumor effect of via an anti-viral immune response. Aberrant DNA methylation of tumor suppressor genes and miRNAs could be a powerful biomarker for diagnosis and treatment of cholangiocarcinoma. Epigenetic therapy with DNA methylation inhibitors hold considerable promise for the treatment of cholangiocarcinoma through re-activation of tumor suppressor genes and miRNAs as well as induction of an anti-viral immune response.
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Life Sciences, Biochemistry; alginate lyase; Vibrio sp.QD-5; alginate
Online: 8 May 2017 (09:27:58 CEST)
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The string of bacteria, Vibrio. sp. QD-5 utilizing alginate, was separated from rotten kelp. The results of genome sequencing showed that the strain QD-5 contained four alginate lyase genes.One of the alginate genes Aly-IV was cloned and linked to the plasmid pET-22b (+). The heterologous expressed alginate lyase aly-IVwas characterized，which possessed the theoretical molecular mass of 62 kDa, and theoretical isoelectric point (pI) of 5.12. - The enzyme aly-IV was purified and the activity reached 1256.78 U/mg, with optimal temperature of 35 oC and pH value of 8.9. Nurtured in the temperature below 25 oC for 30 minutes, the activity was almost stable. The result also suggested that the activity of enzyme was strongly affected by - NaCl whose optimal concentration was 15 mM in a lab environment The TLC and ESI-TOF-MS analysis suggested that the enzyme aly-IV could degrade sodium alginate and polyG in endo-lytic type, producing monomer, dimer and trimmer. So, aly-IV can also be widely applied to make large scale preparation of alginate oligosaccharides with low degree of polymerization (DP).
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Life Sciences, Biochemistry; Vitamin E; vitamin A; maternal serum; lactation; liquid chromatography.
Online: 2 May 2017 (17:20:34 CEST)
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Vitamin A and E are important during pregnancy, the neonatal period, and childhood. The objective of this study was to assess whether maternal RRR-a-tocopherol supplementation affects serum and breast milk retinol. Serum was collected at baseline and twenty days later, and breast milk, at baseline, and on days 1, 7, and 20 after delivery. After the baseline serum collection, the supplemented group (n=16) received a single 400 IU of RRR-α-tocopherol. The control group (n=18) was only performed collections. Retinol and alpha tocopherol levels were determined by liquid chromatography. Serum retinol and alpha tocopherol at baseline and 20 days after delivery indicated proper vitamin A (> 20 µg/dL) and E (> 516 μg/dL) statuses in the control and supplemented groups (p > 0.05). Colostrum retinol levels on days 1 and 7 after delivery were significantly higher in the supplemented group (p = 0.018 and p = 0.012, respectively). Maternal vitamin E supplementation increased colostrum retinol by 52.23% and 111.2%, 24 hours and 7 days, respectively. However, retinol in mature milk did not differ between the groups (p > 0.05). In conclusion, the supplementation with 400 IU of RRR-α-tocopherol improved vitamin A bioavailability in breast milk.
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Life Sciences, Biochemistry; GPCR; ubiquitination; β-arrestin; deubiquitinating enzyme; E3 ubiquitin ligase
Online: 21 April 2017 (06:23:26 CEST)
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G protein-coupled receptors (GPCRs) comprise the largest family of membrane receptors that control many cellular processes and consequently often serve as drug targets. These receptors undergo a strict regulation by mechanisms such as internalization and desensitization, which are strongly influenced by posttranslational modifications. Ubiquitination is a posttranslational modification with a broad range of functions that is currently gaining increased appreciation as a regulator of GPCR activity. The role of ubiquitination in directing GPCRs for lysosomal degradation has already been well-established. Furthermore, this modification can also play a role in targeting membrane and endoplasmic reticulum-associated receptors to the proteasome. Most recently, ubiquitination was also shown to be involved in GPCR signaling. In this review, we present current knowledge on the molecular basis of GPCR regulation by ubiquitination, and highlight the importance of E3 ubiquitin ligases, deubiquitinating enzymes and β-arrestins. Finally, we discuss classical and newly-discovered functions of ubiquitination in controlling GPCR activity.
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Life Sciences, Biochemistry; green tea catechins; prostate cancer; chemoprevention; metabolism; nanoparticles; epigenetic; proteostasis
Online: 31 March 2017 (12:46:15 CEST)
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Green Tea Catechins (GTCs) are a family of chemically related compounds usually classified as antioxidant molecules. Epidemiological evidences, supported by interventional studies, highlighted a more than promising role for GTCs in human Prostate Cancer (PCa) chemoprevention.In the last decades many efforts have been made to gain new insights into the mechanism of action of GTCs. Now it is clear that GTCs anticancer action can no longer be simplistically limited to their direct antioxidant/pro-oxidant properties. Recent contributions to the advancement of knowledge in this field have shown that GTCs specifically interact with cellular targets including, cell surface receptors, lipid rafts and endoplasmic reticulum, modulate gene expression through direct effect on transcription factors or indirect epigenetic mechanisms, interfere with intracellular proteostasis at various levels. Many of the effects observed in vitro are dose and cell context dependent and take place at concentration that cannot be achieved in vivo.Poor intestinal absorption together with an extensive systemic and enteric metabolism influence GTCs bioavailability through still poor understood mechanisms. Recent efforts to develop delivery systems that increase GTCs overall bioavailability, by mean of biopolymeric nanoparticles, represent the main way to translate preclinical results in a real clinical scenario for PCa chemoprevention.
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Life Sciences, Biochemistry; albumin; oxidative stress; exercise; ultra-marathon mountain race; protein oxidation
Online: 17 February 2017 (15:02:03 CET)
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The aim of this study was to examine the oxidation of human serum albumin (HSA) caused by oxidative stress after an exhaustive exercise such as ultra-marathon race. Thus, blood samples from 12 adult runners who underwent a 103 km mountain ultra-marathon race were collected pre- and 24, 48 and 72 h post race. HSA was partially purified using affinity chromatography and then was subjected to Western blot analysis for disulfide dimers determination, indicating oxidation. The results were correlated with those from a previous study in which the same samples were analyzed using different oxidative stress markers and a good correlation with protein carbonyls (PC) at all time points was observed. Moreover there was a significant correlation with static oxidation-reduction potential (sORP) at 24 h, and a negative correlation with capacity oxidation-reduction potential (cORP) at 24 and 48 h. In addition, an individual analysis of albumin dimers exhibited great inter-individual differences. This inter-individual variability in the oxidation of HSA may suggest different interventions (e.g. through diet) in order to confront the effects on athletes’ organism after a strenuous exercise. In conclusion, this study supported the importance of the assessment of albumin dimers as a predictive marker for exercise-induced oxidative stress.
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Life Sciences, Biochemistry; Aquatic-toxic effects; EU chemical regulation; Glyoxal-containing cellulose ether
Online: 31 January 2017 (12:10:39 CET)
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The objective of this study is to investigate the aquatic-toxic effects of glyoxal-containing cellulose ether with four different glyoxal concentrations (0, 1.4, 2.3 and 6.3%) in response to global chemical regulations, e.g., European Union Classification, Labeling and Packaging (EU CLP). Tests of the aquatic-toxic effects of glyoxal-containing cellulose ether on 11 freeze-dried microbial strains, Microcystis aeruginosa, Daphnia magna and zebrafish embryos were designed as an initial stage for toxicity screening, and were performed with the standardized toxicity test guidelines. Glyoxal-containing cellulose ether showed no significant toxic effects in the toxicity tests for the 11 freeze-dried microbial strains, Daphnia magna and zebrafish embryos. Alternatively, 6.3% glyoxal-containing cellulose ether led to more than a 60% reduction of Microcystis aeruginosa growth after 7 days of exposure. Approximately 10% developmental abnormalities (e.g., bent spine) in zebrafish embryos were also observed in the group exposed to 6.3% glyoxal-containing cellulose ether after 6 days of exposure. These results imply that <6.3% glyoxal-containing cellulose ether results in non-toxic effects on the acute toxicity of aquatic organisms. However, ≥6.3% glyoxal-containing cellulose ether may affect the health of aquatic organisms with long-term exposure. In order to better evaluate the eco-safety of cellulosic products contained in glyoxal, further studies regarding the toxic effects of glyoxal-containing cellulose ether with long-term exposure are required. The results from this study allow us to evaluate the auatic-toxic effects of glyoxal-containing cellulosic products, under EU chemical regulations, on the health of aquatic organisms.
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Life Sciences, Biochemistry; ATP-dependent proteolysis, Non-native membrane proteins, Periplasmic domain, Crystal structure, Photosystem II.
Online: 29 December 2016 (17:16:52 CET)
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Prompt removal of misfolded membrane proteins and misassembled membrane protein complexes is essential for membrane homeostasis. However, the elimination of these toxic proteins from the hydrophobic membrane environment has high energetic barriers. Transmembrane FtsH is the only known ATP-dependent protease responsible for this task, unlike other well-studied soluble ATP-dependent proteases. The mechanisms by which FtsH recognizes, unfolds, translocates, and proteolyzes its substrates remain unclear. Here, we report the crystal structures of the Thermotoga maritima FtsH periplasmic domain (PD) in an associative trimeric state at a 1.5-1.95 Å resolution. We also describe the pH-dependent oligomerization states of the isolated PD using dynamic light scattering. These observations help us understand how FtsH recognizes membrane-anchored misfolded proteins.
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Life Sciences, Biochemistry; Polyalthia suaveolens; Uvaria angolensis; Monodora tenuifolia; Plasmodium falciparum K1; toxicity; antimalarial
Online: 8 December 2016 (08:59:49 CET)
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The present study aimed at investigating the in vitro and in vivo susceptibility of malaria parasites to crude extracts and fractions from Polyalthia suaveolens, Uvaria angolensis, and Monodora tenuifolia. The ethanolic extracts were prepared by maceration, and were further partitioned using water, dichloromethane, hexane, and methanol. The most promising fraction was subjected to column chromatography and the sub-fractions tested for activity in vitro. The antiplasmodial effect of extracts and fractions was tested against the Chloroquine resistant (PfK1) strain in 96 wells microtiter plate format using SYBR green florescence assay. The promising fraction was further assessed for cytotoxicity and acute toxicity in Swiss albino mice and subsequently against the rodent malaria parasite, P. berghei. Qualitative phytochemical screening was also performed on the promising fraction. The methanol fractions exerted the overall better effect with that of the twigs of P. suaveolens (PStw(Ace)) showing the highest potency with a IC50 value of 3.24 µg/mL followed by the fractions of leaf of M. tenuifolia (MoTel(Ace), IC50= 3.84 µg/ml) and stem bark of P. suaveolens (IC50= 4.90 µg/ml). The phytochemical screening showed the presence of alkaloids, lactones, and phenols in the more active fraction of P. suaveolens (PStw(Ace)). The chromatographic fractionation of this fraction led to 12 sub-fractions with PS8 sub-fraction being the most active (IC50= 4.42 µg/mL). In vivo, oral administration of 2000 mg/kg b.w of fraction PStw(Ace) in mice showed no signs of toxicity. Also, fraction PStw(Ace) at 400 mg/kg b.w exerted the highest suppressive effect against P. berghei strain B throughout the 4 days experiment (% parasitaemia below 5.2%). Overall, the results achieved supported the use of the three plants in the traditional treatment of malaria in Cameroon. More interestingly, the methanolic fraction of the twigs extract from P. suaveolens might be of interest in future development of an antimalarial phytodrug.
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Life Sciences, Biochemistry; proximal tubule; LC3; ER stress; apoptosis; PKD
Online: 14 November 2016 (04:05:38 CET)
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Aquaporin-11 (AQP11) is an intracellular water channel expressed at the endoplasmic reticulum (ER) of the kidney proximal tubule. Its gene disruption in mice leads to intracellular vacuole formation at one week old and the subsequent development of polycystic kidneys at three week old. As the damaged proximal tubular cells with intracellular vacuoles later form cysts, autophagy may play a role in their survival. We examined the autophagy activity before and after the development of cysts in AQP11(-/-) kidneys. We first observed an enhanced expression of LC3 gene (Map1lc3b) as well as other autophagy-related genes in AQP11(-/-) mice by quantitative PCR analysis. We then examined the formation of autophagosomes visualized by a green fluorescent fusion protein, GFP–LC3 in its transgenic mice. The expression of GFP-LC3 puncta was increased in the proximal tubule of AQP11(-/-) mice before the cyst formation. Interestingly, they were also observed in the cyst-lining epithelial cell. Further PCR analyses revealed the enhanced expression of apoptosis- and ER stress-related caspase genes before and after the cyst formation suggesting that ER stress may have enhanced autophagy. We conclude that autophagy will play an important role in the development and the survival of the kidney cysts in AQP11(-/-) mice.
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Life Sciences, Biochemistry; mercury; antioxidants; cardiovascular diseases; cardiotoxicity; chelating agents
Online: 10 October 2016 (09:49:50 CEST)
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Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence show that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system.
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Life Sciences, Biochemistry; carbonic anhydrase; acetylcholinesterase; β-Lactam; 2-Azetidinone; enzyme inhibition; enzyme purification
Online: 30 September 2016 (05:38:45 CEST)
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β-Lactams are pharmacologically important compounds because of their various biological uses, including antibiotic and so on. β-Lactams were synthesized from benzylidene-inden derivatives and acetoxyacetyl chloride. The inhibitory effect of these compounds was also examined for human carbonic anhydrase I and II (hCA I, and II) and acetylcholinesterase (AChE). The results reveal that β-lactams are inhibitors of hCA I, II and AChE. The Ki values of β-lactams (2a-k) were 0.44-6.29 nM against hCA I, 0.93-8.34 nM against hCA II, and 0.25-1.13 nM against AChE. Our findings indicate that β-lactams (2a-k) inhibit both CA isoenzymes and AChE at low nanomolar concentrations.