Biology subjects

Das, M.

Publications and source records attributed to Das, M..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

SKAP binding to microtubules reduces friction at the kinetochore-microtubule interface and increases attachment stability under force

The kinetochore links chromosomes to spindle microtubules to drive chromosome segregation at cell division. We recently uncovered that the kinetochore complex Astrin-SKAP, which binds microtubules, reduces rather than increases friction at the mammalian kinetochore-microtubule interface. How it does so is not known. Astrin-SKAP could affect how other kinetochore complexes bind microtubules, reducing their friction along microtubules, or it could itself bind microtubules with similar affinity but lower friction than other attachment factors. Using SKAP mutants unable to bind microtubules, live imaging and laser ablation, we show that SKAPs microtubule binding is essential for sister kinetochore coordination, force dissipation at the interface and attachment responsiveness to force changes. Further, we show that SKAPs microtubule binding is essential to prevent chromosome detachment under both spindle forces and microneedle-generated forces. Together, our findings indicate that SKAPs microtubule binding reduces kinetochore friction and increases attachment responsiveness and stability under force. We propose that having complexes with both high and low sliding friction on microtubules, making a mechanically heterogeneous interface, is key to maintaining robust attachments under force and thus accurate segregation.

cell biology↗

bioRxiv2024

LCN2 promotes focal adhesion formation and invasion by stimulating Src activation.

Previous work has demonstrated that Lipocalin2 (LCN2) expression promotes invasion and migration in multiple tumor types. The mechanisms by which LCN2 promotes invasion and migration remain unclear. Previous work from our laboratory demonstrated that LCN2 promotes actin filament formation by inhibiting actin glutathionylation. In this report, we demonstrate that in addition to inhibiting actin glutathionylation, LCN2 stimulates invasion by promoting the formation of focal adhesions, which is independent of the ability of LCN2 to bind iron. LCN2 promotes focal adhesion formation by promoting the activation of c-Src by stimulating the expression of the transcription factor ETS1. ETS1 activates the expression of the protein phosphatase, PTP1B, resulting in the auto-activation of c-Src and increased paxillin phosphorylation leading to focal adhesion formation. These results demonstrate that LCN2 has iron-dependent and independent functions in promoting invasion and highlight the multiple mechanisms by which LCN2 promotes invasion and suggest that c-Src inhibitors could be used to treat invasive colorectal cancer. SUMMARYExpression of LCN2 is elevated in invasive colorectal cancer. We demonstrate that LCN2 promotes invasion by stimulating the formation of focal adhesions by promoting Src activation.

cell biology↗

bioRxiv2024

A Mycobacterium tuberculosis secreted virulence factor disrupts host snRNP biogenesis

We earlier reported that Mycobacterium tuberculosis (Mtb) alters host RNA splicing to help its intracellular growth. Here, we report an unprecedented mechanism whereby a secreted virulence factor from Mtb interferes with the biogenesis of key spliceosomal components, causing an altered RNA splicing pattern. A high-throughput yeast-2-hybrid screen identified several Mtb-secreted proteins that can interact with the host RNA splicing factors (SFs). Through custom-designed in-cell assays, we show that one of those proteins, Rv1435c, targets specific exon-skipping events to alter RNA splicing. We show that Rv14345c or host splicing regulator 1 (hsr1) facilitates direct interaction between Mtb phagosomes and U5 snRNA and SNRPF, key components of the snRNPs. Genetic deletion of hsr1 reverses the specific exon-skipping events caused by WT Mtb infection. The{Delta} hsr1 strain shows compromised growth during ex vivo infection in the macrophages and in vivo infection in the mice. Tissue sections from the WT Mtb or{Delta} hsr1-infected mice showed significant hsr1-dependent SNRPF staining, a phenomenon also noted in the human intestinal tuberculosis (ITB) biopsies. We infer that hsr1 is a virulence factor which alters RNA splicing by interacting with U5snRNA and SNRPF. The splicing regulators from the host and pathogen are novel targets for anti-tuberculosis therapy.

molecular biology↗

bioRxiv2024

Bridging DNA contacts allow Dps from E. coli to condense DNA

The DNA-binding protein from starved cells (Dps) plays a crucial role in maintaining bacterial cell viability during periods of stress. Dps is a nucleoid-associated protein that interacts with DNA to create biomolecular condensates in live bacteria. Purified Dps protein can also rapidly form large complexes when combined with DNA in vitro. However, the mechanism that allows these complexes to nucleate on DNA remains unclear. Here, we examine how DNA topology influences the formation of Dps-DNA complexes. We find that DNA supercoils offer the most preferred template for the nucleation of condensed Dps structures. More generally, bridging contacts between different regions of DNA can facilitate the nucleation of condensed Dps structures. In contrast, Dps shows little affinity for stretched linear DNA before it is relaxed. Once DNA is condensed, Dps forms a stable complex that can form inter-strand contacts with nearby DNA, even without free Dps present in solution. Taken together, our results establish the important role played by bridging contacts between DNA strands in nucleating and stabilizing Dps complexes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/576774v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@1e4d842org.highwire.dtl.DTLVardef@131f3c6org.highwire.dtl.DTLVardef@7b6358org.highwire.dtl.DTLVardef@b73c32_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract.C_FLOATNO Working model of nucleation and formation of Dps-DNA complex. Regions of supercoiled or stochastically bent DNA act as nucleation points for the formation of Dps-DNA complexes by allowing Dps to form bridging contacts. Dps does not readily bind to straight stretches of DNA in isolation. Once Dps-DNA complexes are formed they can form bridging contacts to bind additional DNA. C_FIG

biophysics↗

bioRxiv2024

Curtailed CaSR expression in peripheral blood mononuclear cells is associated with hypertension

The calcium-sensing receptor (CaSR) is a GPCR family member. CaSR is abundantly expressed in the parathyroid gland and controls calcium homeostasis. There are no particular discoveries involving CaSR expression in hypertensive peripheral blood mononuclear cells. We investigated lower CaSR expression in hypertensive human and animal models. Nitric oxide (NO) has an important role in vascular function. Impaired NO production disrupts CaSR-mediated fine adjustment of the intra- and extracellular [Ca2+] gradients. According to the law Ca2+ transportation through Ca channels maintains its connection from the circulatory micro-vascular bed to interstitial space, influenced by capillary and interstitial fluid hydrostatic pressure, as well as oncotic pressure. In that situation, the alterations in Ca2+ microenvironment and dynamics remain unknown. CaSR on circulatory mononuclear cells may detect changes in the Ca2+ microenvironment in the ISF of endothelial cells-VSMC and endothelium lining in hypertension. In this experiment, the decreased expression of CaSR revealed a molecular sensor in the presence of elevated blood pressure.

biochemistry↗

bioRxiv2024

Northeast India: Genetic Inconsistency across Ethnicity and Geography

The genetic landscape of South Asia is intriguing. In a vast geographical region like India, mostly genes follow geography, whereas in a smaller geographical region e.g., Nepal, the genetic landscape is more akin to languages. Moreover, in neighboring regions like East and Southeast Asia, language is the major denominator of the genes. However, these are not just the two alternatives, in many geographical pockets, ethnicity plays a stronger role than either of these. Being a crossroads of South and Southeast Asia, the Himalayan region is mostly populated by people speaking the Trans-Himalayan language. Archaeological and anthropological studies suggest migration and cultural diffusion in this region with the Tibetan plateau in the North. To understand this complex pattern, we have performed a fine-grained genetic analysis of the major Mizo population and its various clans living in the Himalayan geography. We have investigated 110 individuals belonging to seven different clans of Mizo people for a hundred thousand autosomal markers. We have used various statistical methods and tested the role of ethnicity and geography in shaping the genetic landscape of the Himalayan region. In contrast to the East and Southeast Asian genetic landscape, our results suggested that the fine-scaled genetic structure of Northeast India is much more complex and a mixture of interplay between languages, ethnicity, and geography. Allelic frequency-based analyses indicated that a novel Trans-Himalayan ancestry unite all the populations of this region.

evolutionary biology↗

bioRxiv2023

A mitochondrial quality control mechanism reverses the phagosome maturation arrest caused by Mycobacterium tuberculosis

Phagosome maturation arrest (PMA) imposed by Mycobacterium tuberculosis (Mtb) is a classic tool that helps Mtb evade macrophage anti-bacterial responses. The exclusion of RAB7, a small GTPase, from Mtb-phagosomes causes PMA. Here, we report an unexpected mechanism that triggers crosstalk between the mitochondrial quality control (MQC) and the phagosome maturation pathways that reverses the PMA. CRISPR-mediated p62/SQSTM1 depletion (p62KD) does not appear to impact mitochondrial quality. The p62KD cells are restrictive to Mtb growth, triggered by an increasingly oxidative environment and increased lysosomal targeting. The lysosomal targeting of Mtb is facilitated by enhanced TOM20+ mitochondria-derived vesicles (MDVs) biogenesis, a key MQC mechanism. In p62KD cells, TOM20+-MDVs biogenesis is MIRO1/MIRO2-dependent and gets delivered to lysosomes for degradation in a RAB7-dependent manner. Upon infection in p62KD cells, TOM20+-MDVs get extensively targeted to Mtb-phagosomes, inadvertently facilitating RAB7 recruitment, PMA reversal and lysosomal targeting of Mtb; the phenotype also replicated in p62/SQSTM1 knockout cells. Triggering MQC collapse in p62KDcells further diminishes Mtb survival, signifying cooperation between redox- and lysosome-mediated mechanisms. The MQC-anti-bacterial pathway crosstalk could be exploited for host-directed anti-tuberculosis therapies.

microbiology↗

bioRxiv2023

Neutrophil-derived IL-17 limits protective host responses and promotes tuberculosis pathogenesis

The protective correlates of Mycobacterium tuberculosis (Mtb) infection-elicited host immune responses are incompletely understood. Here, we report pro-pathogenic crosstalk involving Ly6G+granulocytes (Ly6G+Gra), IL-17 and COX2. We show that in the lungs of Mtb-infected wildtype mice, either BCG-vaccinated or not, most intracellular bacilli are Ly6G+Gra-resident four weeks post-infection onwards. In the genetically susceptible IFN{psi} -/- mice, excessive Ly6G+Gra infiltration correlates with severe bacteraemia. Neutralizing IL-17 (anti-IL17mAb) and COX2 inhibition by celecoxib reverse Ly6G+Gra infiltration, associated pathology and death in IFN{psi} -/- mice. Surprisingly, Ly6G+Gra also serves as the major source of IL-17 in the lungs of Mtb-infected WT or IFN{psi} -/- mice. The IL-17-COX2-Ly6G+Gra interplay also operates in WT mice. Inhibiting ROR{psi}t, the key transcription factor for IL-17 production or COX2, reduces the bacterial burden in Ly6G+Gra, leading to reduced bacterial burden and pathology in the lungs of WT mice. In the Mtb-infected WT mice, COX2 inhibition abrogates IL-17 levels in the lung homogenates and significantly enhances BCGs protective efficacy, mainly by targeting the Ly6G+Gra-resident Mtb pool, a phenotype also observed when IL-17 is blocked by ROR{psi}t inhibitor. Furthermore, in pulmonary TB patients, high neutrophil count and IL-17 correlated with adverse treatment outcomes. Together, our results suggest that IL-17 and PGE2 are the negative correlates of protection, and we propose targeting the pro-pathogenic IL-17-COX2-Ly6G+Gra axis for TB prevention and therapy.

immunology↗

bioRxiv2023

Cohesin forms fountains at active enhancers in C. elegans

Transcriptional enhancers must locate their target genes with both precision and efficiency. In mammals, this specificity is facilitated by topologically associated domains (TADs), which restrict the enhancer search space through three-dimensional genome organization. In contrast, the nematode genome lacks such TAD-based segmentation despite harboring over 30000 sequences with chromatin signature characteristic of enhancers, thereby raising the question of how enhancer-promoter specificity is achieved. Using high-resolution Hi-C in C. elegans, we identify distinct 3D chromatin structures surrounding active enhancers, which we term fountains. These structures span 38 kb in average, are unique to active enhancers, and are enriched for the major somatic cohesin complex. Fountains collapse upon in vivo cohesin cleavage, indicating their cohesin dependency. Notably, fountains accumulate topological stress, as evidenced by the enrichment of topoisomerases and the psoralen-binding signature of negatively-supercoiled DNA. Functionally, fountain disassembly correlates with transcriptional upregulation of active enhancer-proximal genes, suggesting that fountains act as spatial repressors of enhancer activity. This repression is particularly pronounced for neuronal genes, including the skn-1/Nrf gene, which becomes upregulated, switches isoform and transcription start site upon cohesin loss in a pair of head neurons. Behaviorally, cohesin cleavage alters nematode movement and foraging behavior, linking enhancer-driven transcriptional changes to neural circuit function and organismal phenotypes, reminiscent of pathologies caused by cohesin mutations in humans. Together, our findings uncover fountains as a novel 3D chromatin feature that modulates enhancer activity in a TAD-less genome, establishing a mechanistic link between genome architecture, gene regulation and behavior.

genomics↗

bioRxiv2023

Functional loss of rffG and rfbB, encoding dTDP-glucose 4,6-dehydratase, changes colony morphology, cell shape, motility and virulence in Salmonella Typhimurium

Lipopolysaccharide (LPS) O-antigen and enterobacterial common antigen (ECA) play crucial roles in maintaining the structural integrity of the outer membrane in Gram-negative bacteria. Previous studies conducted with either LPS or ECA mutants have highlighted the importance of these cell surface polysaccharides in the physiology of Salmonella enterica serovar Typhimurium (S. Typhimurium). However, the functional consequences resulting from the abrogation of both O-antigen and ECA synthesis in S. Typhimurium are not well studied. In the present study, we generated single and double gene-deleted mutants of rffG and rfbB, which are paralogs, encoding dTDP-glucose 4,6-dehydratase that catalyze steps in the synthesis of both O-antigen and ECA. The functional loss of both rffG and rfbB ({Delta}rffG{Delta}rfbB), but not in single gene-deleted strains, results in a round cell morphology, smaller colony formation and altered LPS profile. In addition, the {Delta}rffG{Delta}rfbB strain displays defects in outer membrane permeability, causing hypersensitivity to bile and cell wall targeting antibiotics, e.g., meropenem and polymyxin B. Transcriptomic analysis identified flagellar and SPI-1 pathway to be highly down-regulated in the {Delta}rffG{Delta}rfbB strain which leads to impaired swimming and swarming motility and lower adhesion and invasion of HeLa cells. Importantly, the {Delta}rffG{Delta}rfbB strain is less proficient in colonizing Peyers patches, spleen and liver, is unable to induce pro-inflammatory cytokines and is attenuated in both the oral and intra-peritoneal models of S. Typhimurium infection in mice. Overall, this study highlights the importance of rffG and rfbB in maintaining cell wall integrity, colony and cellular morphology, motility and virulence in S. Typhimurium.

microbiology↗

bioRxiv2023

Seasonal plasticity and energy efficiency in migratory buntings is an assemblage of alterations in metabolic and gut microbe adaptations.

Circulatory system is the source of useful metabolites to enable organismal energy demands of muscle during different life states of birds including migration. In this study, we profiled the serum metabolites and fecal microbiome of redheaded buntings (Emberiza bruniceps) exhibiting diurnal non-migratory (nonM) pre-migratory (preM), migratory (M) and post-migratory (posM) states, when exposed to long days (14L:10D). Using gas chromatography, out of the identified 124 serum analytes, 38 showed significant variations (Fold change, VIP) between states. Out of these, 11 metabolites (short chain fatty acids, SCFAs-butanoate and hexanoate, lactate, pyruvate, ethylene and acetate oxime, pyridoxal phosphate (PLP), niacin, L-valine and carboximidic acids viz. phosphatidyl ethanolamine (PE) and diethyl carbamate) involved in energy pathways and enhanced immunity showed higher abundance in M state. While, upsurge of L-valine suggested energy contribution of glucogenic branched chain amino acids (BCAAs) in M state, that of leucine metabolite, was related to higher temperature in posM birds. Gut microbiota was analysed using faeces of buntings (n=6 each) during nonM and M states and alteration in bacterial compositions was observed; faeces of nonM birds were enriched in proteobacteria, while those of M were rich in firmicutes. This study reports the migratory state specific changes in the serum metabolome and faecal microbiome of the buntings and highlights the role of short chain fatty acids, SCFAs and branched chain amino acids, BCAAs during hypermetabolic state of migration.

animal behavior and cognition↗

bioRxiv2023

Mechanistic insights into the role of Ca2+-stimulated AMPK in the secretion of cellulases during carbon stress

The response of filamentous fungi towards recalcitrant carbohydrates is majorly governed by transcriptional activators of cellulase genes; however, little is known about the downstream events beyond transcription. We show here in Penicillium funiculosum that increasing the expression of a transcriptional activator CLR-2 in the catabolically derepressed strain, {Delta}Mig1, didnt exhibit a synergistic effect on cellulase production unless Ca2+ was simultaneously increased. The RNA-seq screen for Ca2+-activated kinases identified SNF1-AMPK and SSP1-AMPKK as being specific to cellulose induction. Deletion of snf1 led to negligible secretion of cellulase upon induction. Quantitative whole-cell proteomics followed by chemical-genetic experiments with snf1-deleted strain showed that Ca2+-signaling channelizes carbon, nitrogen and energy sources towards cellulase production. Further, Ca2+-signaling phosphorylates SNF1-AMPK via SSP1, which in turn downregulates the phospho-HOG1 levels, leading to stimulus for cellulase secretion during carbon stress. The findings reported here are significant for understanding fungal pathology and developing second-generation biorefineries.

cell biology↗

bioRxiv2023

In vitro and in vivo evidences propound therapeutic potential of Lipocalin 2 in cervical carcinoma

Cervical cancer (CC), the second most common in developing countries and the third most common in developed nations, is the fourth most common type of cancer in women overall. The HPV16 high-risk genotype of the virus, which is responsible for about 61% of cervical cancer incidences, was found to have higher LCN2 levels in advanced clinical CC stages. In this study, we assessed the impact of suppressing LCN2 activity after treatment with an anti-LCN2 monoclonal antibody (MAb) in both in vitro and in vivo settings. Anti-LCN2 antibody was found to reduce proliferation and invasion of HeLa cells, the first immortal cells from a HPV positive aggressive adenocarcinoma of the cervix. LCN2 and its ligand MMP9 was found to be highly expressed in the cells and abrogated on treatment with anti-LCN2. The five receptors of LCN2 - SLC22A17, MC1R, MC2R, MC4R and LRP2 were barely detected with or without treatment. Anti-LCN2 Mab caused tumors to regress and soften in vivo, in a xenograft mouse model. Analysis of histology images of the treated and untreated tumor established the necrotic capability of the therapeutic molecule explaining the regression and softening of the tumor. Differential gene expression analysis between untreated and treated tumor proved that LCN2 inhibition abolished the migratory, invasive, and hypoxic pathways while significantly increasing the necrosis and cell death pathways in tumor after treatment with the monoclonal antibody. LCN2 inhibition was shown molecularly to lead to tumor regression via a negative feedback loop of LCN2 through the TNF-IL17 axis exponentially increasing the effect of the anti-LCN2 monoclonal antibody. In conclusion, LCN2 appears to be a viable therapeutic target, and the monoclonal antibody used in this study can be further developed for clinical usage in cervical cancer.

cancer biology↗

bioRxiv2023

Novel CAF-identifiers via transcriptomic analysis in oral cancer patients

BackgroundCancer-associated fibroblasts (CAFs), a prominent component of the tumor microenvironment, plays an important role in tumor development, invasion, and drug resistance. The expression of distinct "CAF markers," which separates CAFs from normal fibroblasts and epithelial cells, have traditionally been used to identify them. These commonly used CAF markers have been reported to differ greatly across microenvironmental subpopulations even within a cancer site. MethodsUsing an unbiased data analysis approach utilizing publicly available and in-house gene expression data from patient derived novel CAF cells, we identified a collection of markers in oral cancer to distinguish CAF populations from tumor epithelia and normal oral fibroblasts. ResultsCOL1A1, SPARC, COL1A2, COL3A1 and TIMP-1 were identified as potential markers which can be utilized to differentiate cancer associated fibroblast from all other cell types including normal fibroblasts in oral cancer.

cancer biology↗

bioRxiv2023

Establishment and Characterization of Three Novel CAF Cell Lines from HNSCC Patients

Due to the high rates of tobacco chewers, smokers, and alcohol consumers in India, Head and Neck Squamous Cell Carcinoma (HNSCC) is one of the primary causes of mortality. Being profoundly varied in nature, treating patients diagnosed with HNSCC can be difficult. An in vitro cell line model is needed to better comprehend the heterogeneity especially via the interaction with components of the microenvironment like Cancer Associated Fibroblasts (CAFs). The effectiveness of creating cell lines from head and neck cancers is, however, poor. Furthermore, except for the two reported earlier by us, no other CAF cell lines are available to study the cross-talk of the tumor with its microenvironment. In this study, we report three novel CAF lines, spontaneously immortalized from HPV negative male patients with habits of tobacco and diagnosed with squamous cell carcinoma of the upper alveolus, larynx and buccal mucosa as opposed to HPV positive non-habitual female patients with cancer of the tongue as previously reported. The CAFs increased the tumorigenicity of epithelial cells in indirect co-culture experiments. Negative staining with EpCAM, CD31 and CD45, while positive staining with FSP-1 determined their fibroblast specific lineage. The developed CAF cultures are the first of their kind from the mentioned sites, and they will be an invaluable tool for learning how tumor-stroma and tumor interact with one another and discovering newer targets and pathways for treating HNSCC.

cancer biology↗

bioRxiv2022

Dlg5 and Cadherins are key to peripheral glia integrity

Glial cells in the peripheral nerve wrap axons to insulate them and ensure efficient conduction of neuronal signals. In the myelin sheath, it is proposed that the autotypic tight junctions and adherens junctions form glia-glia complexes that stabilize the glia sheath in myelinating glia. Yet the role of adhesion junctions in non-myelinating glia of vertebrates or invertebrates has not been clearly established. Many components of adhering junctions contain PDZ (PSD-95, Dlg, ZO1) domains or are recruited to these junctions by PDZ binding motifs. To test for the role of PDZ domain proteins in glial sheath formation, we carried out an RNAi screen using Drosophila melanogaster to knockdown each of the 66 predicted PDZ domain proteins in the peripheral glia. We identified six PDZ genes with potential roles in glial morphology, and further investigated Discs-large 5 (Dlg5), a scaffolding protein with no previously known function in glia. Knockdown of Dlg5 disrupts subperineurial glia (SPG) morphology, including gaps in the membrane that coincide with disruption of septate junction proteins. To further our investigation of Dlg5, we focused on cadherins and found both N-Cadherin and E-Cadherin are expressed throughout peripheral glia. Knockdown of E-Cadherin phenocopied the loss of Dlg5 leading to gaps in the SPG and septate junctions while only simultaneous loss of both N-Cadherins (NCad, and CadN2) had the same effect. The loss of all three Cadherins enhanced these phenotypes as did loss of Dlg5 when paired with cadherin knockdown. This leads to a model where Dlg5 plays a role in conjunction with cadherins in glial membrane stabilization and septate junction formation in the subperineurial glia.

neuroscience↗

bioRxiv2022

Comparative efficacy of antiviral strategies targeting different stages of the viral life cycle: A viral quasispecies dynamics study

While the COVID-19 pandemic continues to impact public health worldwide significantly, the use of antiviral drugs and therapies has dramatically reduced the instances of severe disease and death. More broadly, the unprecedented use of antivirals also provides hope for preventing and mitigating similar viral outbreaks in the future. Here we ask: What are the comparative impact of antiviral therapeutics targeting different stages of the viral lifecycle? How do antiviral therapeutics impact the viral population in the bloodstream, or in other words, the viral load in high and low-immunity individuals? To address these questions, we use a model of viral quasispecies dynamics to examine the efficacy of antiviral strategies targeting three critical aspects of the viral life cycle, fecundity, reproduction rate, or infection rate. We find a linear relationship of the viral load with the change in fecundity and a power law with the change in the reproduction rate of the virus, with the viral load decreasing as the fecundity and the reproduction rates are decreased. Interestingly, however, for antivirals that target the infection rate, the viral load changes non-monotonically with the change in infection rate; the viral population initially increases and then decreases as the infection rate is decreased. The initial increase is especially pronounced for individuals with low immunity. By examining the viral population inside cells for such cases, we found that the therapeutics are only effective in such individuals if they stop the infection process entirely. Otherwise, the viral population inside cells does not go extinct. Our results predict the effectiveness of different antiviral strategies for COVID-19 and similar viral diseases and provide insights into the susceptibility of individuals with low immunity to effects like long covid.

biophysics↗

bioRxiv2022

Recombinant Human ACE2-Fc : A promising therapy for SARS-CoV2 infection

SARS-CoV2 entry is mediated by binding of viral spike-protein(S) to the transmembrane Angiotensin-Converting Enzyme-2 (ACE2) of the host cell. Thus, to prevent transmission of disease, strategies to abrogate the interaction are important. However, ACE2 cannot be blocked since its normal function is to convert the Angiotensin II peptide to Angiotensin(1-7) to reduce hypertension. This work reports a recombinant cell line secreting soluble ACE2-ectopic domain (MFcS2), modified to increase binding and production efficacy and fused to human immunoglobulin-Fc. While maintaining its enzymatic activity, the molecule trapped and neutralized SARS CoV2 virus in vitro with an IC50 of 64 nM. In vivo, with no pathology in the vital organs, it inhibited the viral load in lungs in SARS-CoV2 infected Golden-Syrian-hamster. The Intravenous pharmacokinetic profiling of MFcS2 in hamster at a dose of 5 mg/Kg presented a maximum serum concentration of 23.45 {micro}g/mL with a half-life of 29.5 hrs. These results suggest that MFcS2 could be used as an effective decoy based therapeutic strategy to treat COVID19. This work also reports usage of a novel oral-cancer cell line as in vitro model of SARS-Cov2 infection, validated by over expressing viral-defence pathways upon RNA-seq analysis and over-expression of ACE2 and TMPRSS upon growth in hyperglycaemic condition.

molecular biology↗