Subject: Life Sciences, Cell & Developmental Biology Keywords: environment; virus; pollutant; evolution; exaptation; stem cells; transposons; APOBEC; ADAR,; ORF2p; cancer; Eco-Evo-Devo; symbiosis; ecological genomics; environmental stress; genetic recombination; biological plasticity; hypermutation; epigenetics; fractal systems; natural selection
Online: 19 July 2020 (19:35:46 CEST)
This article challenges the notion of the randomness of mutations in eukaryotic cells by unveiling stress-induced human non-random genome editing mechanisms. To account for the existence of such mechanisms, I have developed molecular concepts of the cell environment and cell environmental stressors and, making use of a large quantity of published data, hypothesized the origin of some crucial biological leaps along the evolutionary path of life on Earth under the pressure of natural selection, in particular, 1) virus-cell mating as a primordial form of sexual recombination and symbiosis; 2) Lamarckian CRISPR-Cas systems; 3) eukaryotic gene development; 4) antiviral activity of retrotransposon-guided mutagenic enzymes and finally; 5) the exaptation of antiviral mutagenic mechanisms to stress-induced genome editing mechanisms directed at “hypertranscribed” endogenous genes. Genes transcribed at their maximum rate (hypertranscribed), yet still unable to meet new chronic environmental demands generated by “pollution”, are inadequate and generate more and more intronic retrotransposon transcripts. In this scenario, RNA-guided mutagenic enzymes (e.g. AID/APOBECs), which have been shown to bind to retrotransposon RNA-repetitive sequences, would be surgically targeted by intronic retrotransposons on opened chromatin regions of the same “hypertranscribed” genes. RNA-guided mutagenic enzymes may therefore “Lamarkianly” generate single nucleotide polymorphisms (SNP) and copy number variations (CNV), as well as transposon transposition and chromosomal translocations in the restricted areas of hyperfunctional and inadequate genes, leaving intact the rest of the genome. CNV and SNP of hypertranscribed genes may allow cells to surgically explore a new fitness scenario, which increases their adaptability to stressful environmental conditions. Like the mechanisms of immunoglobulin somatic hypermutation, non-random genome editing mechanisms may generate several cell mutants, and those codifying for the most environmentally-adequate proteins would have a survival advantage and would therefore be Darwinianly selected. Non-random genome editing mechanisms represent a link between environmental changes and biological novelty and plasticity, and provide a molecular basis to reconcile gene-centered and “ecological” views of evolution.
BRIEF REPORT | doi:10.20944/preprints202003.0338.v3
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: Severe Acute Respiratory Syndrome Coronavirus-2; (soluble) ACE2; eosinophil; asthma; IL-10; Lung fibrosis; hypercapnic acidosis; hypoxia; infarction; hypertension; cardiac dysfunction; respiratory distress; coagulopathy; Angiotensin; renin; Ang (1-7); Ang (1-9); Mas receptor; AT2 receptor
Online: 6 May 2020 (04:40:25 CEST)
The article describes the rational for inhibition of the angiotensin-converting enzyme 2 (ACE2) pathways as specific targets in patients infected by SARS-CoV-2 in order to prevent the establishment of positive feedback loops triggered by COVID-19 in some predisposed subjects. Making use of a large quantity of published reports in which human/rodent ACE2 pathway inhibitors were administered in vivo, it is hypothesized a possible therapeutic pharmacological intervention through an inhibition strategy of the zinc metalloprotease ACE2 and its downstream pathway for SARS-CoV-2 patients. Of even more interest, metal (zinc) chelators and renin inhibitors (both FDA approved drugs) may also work alone or in combination in inhibiting the positive feedback loops, initially triggered by COVID-19 and subsequently sustained by hypoxia independently on viral trigger, when both arms of renin-angiotensin system (ACE2 and ACE) are upregulated, leading to critical, advanced and untreatable stages of the disease.
Subject: Life Sciences, Immunology Keywords: NK cell biology; NK cell subsets; NK activating receptors; cell adhesion molecules; granule polarization; cytotoxicity assay; cis interactions; trogocytosis; NK cell degranulation; NK-Based Immunotherapies
Online: 14 February 2020 (03:13:05 CET)
NK population is characterized by distinct NK cell subsets which respond differently to the various activating stimuli. For this reason, the determination of the optimal cytotoxic activation of the different NK subsets can be a crucial aspect to be exploited to counter cancer cells in oncologic patients. To evaluate how the triggering of different combination of activating receptors can affect the cytotoxic responses of different NK cell subsets, we developed a microbead-based degranulation assay. By using this new assay, we were able to detect CD107a+ degranulating NK cells even within the less cytotoxic subsets (i.e. resting CD56bright and unlicensed CD56dim NK cells), thus demonstrating its high sensitivity. Interestingly, signals delivered by the co-engagement of NKp46 with 2B4, but not with CD2 or DNAM-1, strongly cooperate to enhance degranulation on both licensed and unlicensed CD56dim NK cells. Of note, 2B4 is known to bind CD48 hematopoietic antigen, therefore this observation may provide the rationale why CD56dim subset expansion correlates with successful hematopoietic stem cell transplantation mediated by alloreactive NK cells against host T, DC and leukemic cells, while sparing host non-hematopoietic tissues and graft versus host disease. The assay further confirms that activation of LFA-1 on NK cells leads to their granule polarization, even if, in some cases, this also takes to an inhibition of NK degranulation, suggesting that LFA-1 engagement by ICAMs on target cells may differently affect NK cell response. Finally, we observed that NK cells undergo a time-dependent spontaneous (cytokine-independent) activation after blood withdrawal, an aspect that may strongly bias the evaluation of the resting NK cell response. Altogether our data may pave the way to develop new NK activation and expansion strategies that target the highly cytotoxic CD56dim NK cells and can be feasible and useful for cancer and viral infection treatment.