Biology subjects

Ghosh, S.

Publications and source records attributed to Ghosh, S..

At least 271 records · Page 15Linked to original sources

bioRxiv2022

Immunomodulatory actions of a kynurenine-derived endogenous electrophile.

The inflammatory upregulation of kynurenine metabolism induces immunomodulatory responses via incompletely understood mechanisms. We report that increases in cellular and systemic kynurenine levels yield the electrophilic derivative kynurenine-carboxyketoalkene (Kyn-CKA), as evidenced by the accumulation of thiol-conjugates and saturated metabolites. Under physiological conditions, Kyn-CKA induces Nrf2-regulated genes and inhibits NF-{kappa}B and NLRP3-dependent pro-inflammatory signaling. Sickle Cell Disease (SCD) is a hereditary hemolytic condition characterized by basal inflammation and recurrent vaso-occlusive crises. Both a transgenic SCD murine model and SCD patients exhibit increased kynurenine synthesis and elevated Kyn-CKA metabolite levels. Plasma hemin and kynurenine concentrations are positively correlated, indicating that Kyn-CKA synthesis in SCD is upregulated during pathogenic vascular stress. Remarkably, exogenous administration of Kyn-CKA abrogated pulmonary microvasculature occlusion in SCD mice, an important factor in the development of lung injury. These findings demonstrate that the upregulation of kynurenine synthesis and its metabolism to Kyn-CKA is an adaptive response that attenuates inflammation and protects tissues. One-Sentence SummaryKyn-CKA is a kynurenine-derived signaling mediator that transduces its immunomodulatory protective actions and attenuates vaso-occlusion in sickle cell disease.

immunology↗

bioRxiv2021

Phosphorylation of interfacial phosphosite leads to increased binding of Rap-Raf complex

The effect of phosphorylation of a serine residue in the Rap protein, residing at the complex interface of Rap-Raf complex is studied using atomistic molecular dynamics simulations. As the phosphosite of interest (SER39) is buried at the interface of the Rap-Raf complex, phosphorylation of only Rap protein was simulated and then complexed with the RBD of Raf for further analysis of complex stability. Our simulations reveal that the phosophorylation increases the binding of complex through strong electrostatic interactions and changes the charge distribution of the interface significantly. This is manifested as an increase in stable salt-bridge interactions between the Rap and Raf of the complex. Network analysis clearly shows that the phosphorylation of SER39 reorganizes the community network to include the entire region of Raf chain, including, Raf L4 loop potentially affecting downstream signalling.

biophysics↗

bioRxiv2021

Isolation and Characterization of SARS-CoV-2 strains circulating in Eastern India.

Emergence of SARS-CoV-2 as a serious pandemic has altered the global socioeconomic dynamics. The wide prevalence, high death counts and rapid emergence of new variants urge for establishment of research infrastructure to facilitate rapid development of efficient therapeutic modalities and preventive measures. In agreement with this, five SARS-CoV2 strains (ILS01, ILS02, ILS03, ILS15 and ILS24) of four different clades (19A, 19B, 20A and 20B) were isolated from patient swab samples collected during the 1st COVID-19 wave in Odisha, India. The viral isolates were adapted to in-vitro cultures and further characterized to identify strain specific variations in viral growth characteristics. All the five isolates showed substantial amount of virus induced CPE however ILS03 belonging to 20A clade displayed highest level of CPE. Time kinetics experiment revealed spike protein expression was evident after 16th hours post infection in all five isolates. ILS03 induced around 90% of cytotoxicity. Further, the susceptibility of various cell lines (human hepatoma cell line (Huh-7), CaCo2 cell line, HEK-293T cells, Vero, Vero-E6, BHK-21, THP-1 cell line and RAW 264.7 cells) were assessed. Surprisingly, it was found that the human monocyte cells THP-1 and murine macrophage cell line RAW 264.7 were permissive to all the SARS-CoV-2 isolates. The neutralization susceptibility of viral isolates to vaccine-induced antibodies was determined using sera from individuals vaccinated in the Government run vaccine drive in India. The micro-neutralization assay suggested that both Covaxin and Covishield vaccines were equally effective (100% neutralization) against all of the isolates. The whole genome sequencing of culture adapted viral isolates and viral genome from patient oropharyngeal swab sample suggested that repetitive passaging of SARS-CoV2 virus in Vero-E6 cells did not lead to emergence of many mutations during the adaptation in cell culture. Phylogenetic analyses revealed that the five isolates clustered to respective clades. The major goal was to isolate and adapt SARS-CoV-2 viruses in in-vitro cell culture with minimal modification to facilitate research activities involved in understanding the molecular virology, host-virus interactions, application of these strains for drug discovery and animal challenge models development which eventually will contribute towards the development of effective and reliable therapeutics.

microbiology↗

bioRxiv2021

ESR2 regulates indian hedgehog signaling in neonatal rat ovary

The transcriptional regulatory function of estrogen receptor {beta} (ESR2) is essential for the regulation of primordial follicle activation (PFA). Increased PFA due to the loss of ESR2 becomes evident as early as postnatal day 8 (PND8). To identify the ESR2-regulated genes that control PFA, we performed RNA-seq analyses of wildtype, and Esr2 knockout (Esr2KO) neonatal rat ovaries collected on PND4, PND6, and PND8. Among the differentially expressed genes in Esr2KO ovaries, indian hedgehog (Ihh) displayed the highest downregulation among the ovary enriched genes. IHH regulated genes including Hhip as well as the steroidogenic enzymes were also downregulated in Esr2KO rat ovaries. Remarkably, the expression of Ihh in Esr2KO ovaries was not upregulated despite the high levels of Gdf9 and Bmp15, which are known regulators of Ihh expression in granulosa cells. Our findings suggest that indian hedgehog signaling in the neonatal rat ovary is dependent on ESR2.

developmental biology↗

bioRxiv2021

High throughput screening of a new fluorescent G-quadruplex ligand having telomerase inhibitory activity in human A549 cells

Genome-wide analysis showed that putative G-quadruplex DNA structures are prevalent in the human genome. The presence of G-quadruplex structure in the telomere and promoter region of certain oncogenes inspired people to use G-quadruplex ligand as anti-cancer agents. G-quadruplex structures, stabilized by ligand at telomere are resolved by telomerase making the cancer cells resistant to G-quadruplex ligand. So, identification of a new G-quadruplex ligand having anti-telomerase activity would be a promising strategy for cancer therapy as about 85% of human cancers are telomerase positive. A set of the drug-like compounds were screened from the ZINC database randomly and 2284 ligands were chosen following Lipinskis rule of five that were docked with five different G-quadruplex DNA sequences in idock. We screened 43 potential G-quadruplex binders using Z-score as a normalization scoring function. The compound (ZINC ID-05220992) gave the best score (average idock = -10.17 kcal/mol, average normalized idock = -3.42). We performed G4 FID assay, CD analysis to understand its binding with three different G-quadruplex DNA sequences, and checked its anti-telomerase activity in A549 cells using TRAP assay. We observed that this compound had an intrinsic fluorescence, capability to stain live cells with a blue fluorescence, and a specific affinity to only 22AG out of three different G-quadruplex DNA sequences under study. It showed cytotoxicity, good permeability to live cells, and a significant reduction of telomerase activity in human A549 cells at a very low dose. So, this compound has strong potential to be an anti-cancer drug. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/470216v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@116cce1org.highwire.dtl.DTLVardef@1e500c1org.highwire.dtl.DTLVardef@194a0b3org.highwire.dtl.DTLVardef@c258fe_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIA set of compounds were screened randomly by a High throughput method and Lipinskis rule of five from ZINC database to identify potential G4-binders. C_LIO_LIThe compound (ZINC ID-05220992) was screened after docking with five G-quadruplex DNA C_LIO_LIIt binds G-quadruplex DNA 22AG as detected by TO displacement and CD spectroscopy. C_LIO_LIIt inhibits telomerase activity in A549 cells and also cytotoxic to this cell. C_LIO_LIIt penetrates live A549 cell in culture and stains it with blue fluorescence C_LI

molecular biology↗

bioRxiv2021

Joint Learning of Full-structure Noise in Hierarchical Bayesian Regression Models

We consider the reconstruction of brain activity from electroencephalography (EEG). This inverse problem can be formulated as a linear regression with independent Gaussian scale mixture priors for both the source and noise components. Crucial factors influencing the accuracy of the source estimation are not only the noise level but also its correlation structure, but existing approaches have not addressed the estimation of noise covariance matrices with full structure. To address this shortcoming, we develop hierarchical Bayesian (type-II maximum likelihood) models for observations with latent variables for source and noise, which are estimated jointly from data. As an extension to classical sparse Bayesian learning (SBL), where across-sensor observations are assumed to be independent and identically distributed, we consider Gaussian noise with full covariance structure. Using the majorization-maximization framework and Riemannian geometry, we derive an efficient algorithm for updating the noise covariance along the manifold of positive definite matrices. We demonstrate that our algorithm has guaranteed and fast convergence and validate it in simulations and with real MEG data. Our results demonstrate that the novel framework significantly improves upon state-of-the-art techniques in the real-world scenario where the noise is indeed non-diagonal and full-structured. Our method has applications in many domains beyond biomagnetic inverse problems.

neuroscience↗

bioRxiv2021

Combining dictionary- and rule-based approximate entity linking with tuned BioBERT

Chemical named entity recognition (NER) is a significant step for many downstream applications like entity linking for the chemical text-mining pipeline. However, the identification of chemical entities in a biomedical text is a challenging task due to the diverse morphology of chemical entities and the different types of chemical nomenclature. In this work, we describe our approach that was submitted for BioCreative version 7 challenge Track 2, focusing on the Chemical Identification task for identifying chemical entities and entity linking, using MeSH. For this purpose, we have applied a two-stage approach as follows (a) usage of fine-tuned BioBERT for identification of chemical entities (b) semantic approximate search in MeSH and PubChem databases for entity linking. There was some friction between the two approaches, as our rule-based approach did not harmonise optimally with partially recognized words forwarded by the BERT component. For our future work, we aim to resolve the issue of the artefacts arising from BERT tokenizers and develop joint learning of chemical named entity recognition and entity linking using pre-trained transformer-based models and compare their performance with our preliminary approach. Next, we will improve the efficiency of our approximate search in reference databases during entity linking. This task is non-trivial as it entails determining similarity scores of large sets of trees with respect to a query tree. Ideally, this will enable flexible parametrization and rule selection for the entity linking search.

bioinformatics↗

bioRxiv2021

Natural variation in gene expression and Zika virus susceptibility revealed by villages of neural progenitor cells

Variation in the human genome contributes to abundant diversity in human traits and vulnerabilities, but the underlying molecular and cellular mechanisms are not yet known, and will need scalable approaches to accelerate their recognition. Here, we advanced and applied an experimental platform that analyzes genetic, molecular, and phenotypic heterogeneity across cells from very many human donors cultured in a single, shared in vitro environment, with algorithms (Dropulation and Census-seq) for assigning phenotypes to individual donors. We used natural genetic variation and synthetic (CRISPR-Cas9) genetic perturbations to analyze the vulnerability of neural progenitor cells to infection with Zika virus. These analyses identified a common variant in the antiviral IFITM3 gene that regulated IFITM3 expression and explained most inter-individual variation in NPCs susceptibility to Zika virus infectivity. These and other approaches could provide scalable ways to recognize the impact of genes and genetic variation on cellular phenotypes. HIGHLIGHTSO_LIMeasuring cellular phenotypes in iPSCs and hPSC-derived NPCs from many donors C_LIO_LIEffects of donor sex, cell source, genetic and other variables on hPSC RNA expression C_LIO_LINatural genetic variation and synthetic perturbation screens both identify IFITM3 in NPC susceptibility to Zika virus C_LIO_LIA common genetic variant in IFITM3 explains most inter-individual variation in NPC susceptibility to Zika virus C_LI

genomics↗

bioRxiv2021

A novel innate pathogen sensing strategy involving ubiquitination of bacterial surface proteins

Sensing of pathogens by ubiquitination is critical for maintaining cytosolic sanctity. However, universal ubiquitination targets on bacteria, especially of proteinaceous origin, remain unidentified. Here, we unveil a novel strategy, involving recognition of degron-like motifs for identification of first protein-based ubiquitination substrates on phylogenetically distinct bacteria. Such motifs can form a new class of intra-cytosolic pathogen associated molecular patterns (PAMPs) as their incorporation enables identification of non-ubiquitin targets by host Ub-ligases. We find SCFFBW7 E3-ligase, supported by the regulatory kinase, GSK3{beta}, is crucial for effective pathogen detection and clearance. This may explain the enhanced risk of infections in Chronic Lymphocytic Leukaemia patients bearing FBXW7 mutations. We conclude that exploitation of such ubiquitous pathogen sensing strategy allows conservation of cellular resources and boost anti-microbial immunity. One Sentence SummaryUbiquitination of bacterial surface proteins fosters sensing and clearance of diverse pathogens

microbiology↗

bioRxiv2021

Control of protein activity by photoinduced spin polarized charge reorganization

Considerable electric fields are present within living cells, and the role of bioelectricity has been well established at the organismal level. Yet little is known about electric-field effects on protein function. Here we use phototriggered charge injection from a site-specifically attached ruthenium photosensitizer to directly demonstrate the effects of charge redistribution within a protein. We find that binding of an antibody to phosphoglycerate kinase (PGK) is increased two folds under illumination. Remarkably, illumination is found to suppress the enzymatic activity of PGK by a factor as large as three. These responses are sensitive to the photosensitizer position on the protein. Surprisingly, left (but not right) circularly polarized light elicits these responses, indicating that the electrons involved in the observed dynamics are spin polarized, due to spin filtration by protein chiral structures. Our results directly establish the contribution of electrical polarization as an allosteric signal within proteins. Future experiments with phototriggered charge injection will allow delineation of charge rearrangement pathways within proteins and will further depict their effects on protein function. Significance StatementThe role of well-placed charges within proteins in mediating biological functions, from protein-protein association to enzyme kinetics, is well documented. Here we go beyond this static picture and show that charge motions can exert significant effects on protein function. Injecting charge from a photosensitizer, we demonstrate a three-fold decrease in enzymatic activity and a two-fold increase of antibody-antigen binding. These effects depend on the specific position of the photosensitizer on the protein. Our results point to charge reorganization as a form of allostery that complements known allosteric mechanisms such as conformational changes and dynamics.

biophysics↗

bioRxiv2021

A Mediterranean-like fat blend protects against the development of severe colitis in the mucin-2 deficient murine model

The Mediterranean diet (MD) is a health-promoting, moderate fat diet (~ 40% energy). It is not known if the blend of fats found in the MD contribute to the beneficial protective effects. We compared the MD fat blend (high monounsaturated, 2:1 n-6:n-3 polyunsaturated and moderate saturated fat) to isocaloric diets composed with corn oil (CO, n-6 polyunsaturated-rich), olive oil (high monounsaturated-rich) or milk fat (MF, saturated-rich) on spontaneous colitis development in Muc2-/- mice. The MD resulted in lower clinical and histopathological scores, and induced tolerogenic CD103+CD11b+ dendritic, Th22 and IL-17+IL-22+ cells important for intestinal barrier repair. MD also reduced attendant insulin resistance and a shift to a higher health-promoting gut microbes including Lactobacillus B. animalis and Muribaculaceae, whereas CO showed higher prevalence of mucin-degraders (Akkermansia muciniphila) and colitis promoters (Enterobacteriaceae). Our findings suggest that the MD fat blend could be recommended as a maintenance diet for colitis.

immunology↗

bioRxiv2021

Enzyme Aggregation and Fragmentation Induced by Catalysis Relevant Species

It is usually assumed that enzymes retain their native structure during catalysis. However, the aggregation and fragmentation of proteins can be difficult to detect and sometimes conclusions are drawn based on the assumption that the protein is in its native form. We have examined three model enzymes, alkaline phosphatase (AkP), hexokinase (HK) and glucose oxidase (GOx). We find that these enzymes aggregate or fragment after addition of chemical species directly related to their catalysis. We used several independent techniques to study this behavior. Specifically, we found that glucose oxidase and hexokinase fragment in the presence of D-Glucose but not L-glucose, while hexokinase aggregates in the presence of Mg2+ ion and either ATP or ADP at low pH. Alkaline phosphatase aggregates in the presence of Zn2+ ion and inorganic phosphate. The aggregation of hexokinase and alkaline phosphatase does not appear to attenuate their catalytic activity. Our study indicates that specific multimeric structures of native enzymes may not be retained during catalysis and suggests pathways for different enzymes to associate or separate over the course of substrate turnover.

biophysics↗

bioRxiv2021

Analysis of changes occurring in Codon Positions due to mutations through the cellular automata transition rules

Variation in the nucleotides of a codon may cause variations in the evolutionary patterns of a DNA or amino acid sequence. To address the capability of each position of a codon to have non-synonymous mutations, the concept of degree of mutation has been introduced. The degree of mutation of a particular position of codon defines the number of non-synonymous mutations occurring for the substitution of nucleotides at each position of a codon, when other two positions of that codon remain unaltered. A Cellular Automaton (CA), is used as a tool to model the mutations of any one of the four DNA bases A, C, T and G at a time where the DNA bases correspond to the states of the CA cells. Point mutation (substitution type) of a codon which characterizes changes in the amino acids, have been associated with local transition rules of a CA. Though there can be [Formula] transitions of a 4-state CA with 3-neighbourhood cells, here it has been possible to represent all possible point mutations of a codon in terms of combinations of 16 local transition functions of the CA. Further these rules are divided into 4 classes of equivalence. Also, according to the nature of mutations, the 16 local CA rules of substitutions are classified into 3 sets namely, No Mutation, Transition and Transversion. The experiment has been carried out with three sets of single nucleotide variations(SNVs) of three different viruses but the symptoms of the diseases caused by them are to some extent similar to each other. They are SARS-CoV-1, SARS-CoV-2 and H1N1 Type A viruses. The aim is to understand the impact of nucleotide substitutions at different positions of a codon with respect to a particular disease phenotype.

systems biology↗

bioRxiv2021

Spontaneous emergence of non-convertible cell states with CD24-High phenotype results in phenotypic heterogeneity that associates with poor prognosis in oral cancer

PurposeCellular dynamics between phenotypically heterogeneous subpopulations of cancer cells within individual tumor is shown to be responsible for drug tolerance and overall poor prognosis; however, evidences were largely missing in oral cancer. Therefore, this study was undertaken to describe the dynamic phenotypic states among oral cancer cells, its influence on transcriptomic heterogeneity as well as its clinical significance. Experimental DesignWe multiplexed phenotypic markers of putative oral-stem-like cancer cells (SLCCs) and characterized diversity among CD44-positive oral cancer cell subpopulations with respect to distinct expression of CD24 and aldehyde dehydrogenase (ALDH)-activity in multiple cell lines. Population trajectories were characterized by Markov model and cell states were defined based on the population specific RNA sequencing (RNAseq). ssGSEA based gene expression signatures were explore for prognostic significance. ResultsOral cancer cells followed two distinct patterns of spontaneous repopulation dynamics with stochastic inter-conversions on ALDH-axis, however a strict non-interconvertible transition on CD24-axis. Interestingly, plastic ALDH-axis was harnessed to enrich ALDHHigh subpopulations in response to Cisplatin treatment, to adapt a drug tolerant state. Phenotype-specific RNAseq results suggested the organization of subpopulations into hierarchical structure with possible maintenance of intermediate states of stemness within the differentiating oral cancer cells. Further, survival analysis with each subpopulation-specific gene signature strongly suggested that the cell-state dynamics may act as possible mechanism to drive ITH, resulting in poor prognosis in patient. ConclusionsOur results emphasized the prognostic power of the population dynamics in oral cancer. Importantly, we have described the phenotypic-composition of heterogeneous subpopulations critical for global tumor behaviour in oral cancer; which is a prerequisite knowledge important for precision treatment, however largely lacking for most solid tumors. Graphical AbstractWe have characterized diversity among CD44-positive oral cancer cells lines with respect to distinct expression of CD24 and ALDH-activity. Subpopulations showed stochastic inter-conversions on ALDH-axis but a strict non-interconvertible transition of CD24Low to CD24High phenotype, even in response to chemotherapy-induced stress. RNAseq study suggested the organization of subpopulations into hierarchical structure with possible maintenance of intermediate alternate states of stemness within the differentiating oral cancer cells. The described population dynamics demonstrtaed influence tumor behaviour possibly by increasing intratumoral heterogeneity in aggressive oral tumors. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/457509v3_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@1dc6a7org.highwire.dtl.DTLVardef@dd0948org.highwire.dtl.DTLVardef@18c9603org.highwire.dtl.DTLVardef@cca8fb_HPS_FORMAT_FIGEXP M_FIG C_FIG Translational relevanceIntratumoral heterogeneity (ITH) has been the clinically important factor, impacting aggressive cancer behaviour, drug tolerance and overall poor prognosis. Recent high-throughput studies have provided better cellular and molecular resolution of ITH; however, the prerequisite knowledge which defines the composition of subpopulations critical for global tumor behaviour is majorly lacking for most of the solid tumors. By combining phenotypic markers, we have defined four subpopulations of oral cancer cells. These subpopulations showed stochastic inter-conversions as well as a strict non-interconvertible transition among them to acheive heterogeneity. Importantly, transcriptional states of each subpopulations indicated a clinically relevant signatures for patient prognosis. Also, we observed interconversions of these subpopulations in response to Cisplatin to accumulate drug-tolerant cell state, as rapid and reversible strategy to respond to chemotherapy induced stress. Thus, the characteristics of described phenotypic subgroups may be translated to the clinic for estimating the extent of intratumoral heterogeneity in oral cancer patients.

cancer biology↗

bioRxiv2021

Cellular heterogeneity and molecular reprogramming of host response during influenza acute lung injury

Acute lung injury (ALI) caused by influenza A virus (IAV or influenza) manifests from dysregulated cellular interactions between hematopoietic and non-hematopoietic cells that develop into a pathologic host response. However, the lungs diverse cellular framework that dictates the pathologic host response and acute lung injury remains incompletely understood. We performed a single-cell RNA-seq (scRNA-seq) analysis of total lung cells in mice from severe influenza to examine the cellular heterogeneity and cell-specific regulation of host response. We observed that IAV infection resulted in significant myelopoiesis, predominantly monocyte, and macrophage subsets, which constituted over 50% of total immune cells. IAV infection resulted in the significant loss of endothelial and fibroblast cells, representing the most predominant non-hematopoietic cells and crucial to regulating inflammatory response and barrier integrity. We also show the cell-cell communication dynamics of interferon and chemokine signaling and global regulation of these responses in transition from homeostatic to IAV infection state. These data highlight a robust application of scRNA-seq technology in establishing the atlas of cellular heterogeneity from its homeostatic transition to infection state and the host response regulation in IAV-mediated lung pathology.

immunology↗

bioRxiv2021

Neuronal correlates of attentional selectivity and intensity in visual area V4 are invariant of motivational context

Flexibly switching attentional strategies is crucial for adaptive behavior in changing environments. Depending on the context, task demand employs different degrees of the two fundamental components of attention- attentional selectivity (preferentially attending to one location in visual space) and effort (the total non-selective intensity of attention). Neuronal responses in the visual cortex that show modulation with changes in either selective attention or effort are reported to partially represent motivational aspect of the task context. The relative contributions and interactions of these two components of attention to modulate neuronal signals and their sensitivity to distinct motivational drives are poorly understood. To address this question, we independently controlled monkeys spatially selective attention and non-selective attentional intensity in the same experimental session during a novel visual orientation change detection task. Attention was controlled either by adjusting the relative difficulty of the orientation changes at the two locations or by the reward associated with stimuli at two locations while simultaneously recording spikes from populations of neurons in area V4. We found that V4 neurons are robustly modulated by either selective attention or attentional intensity. Notably, as attentional selectivity for a neurons receptive field location decreased, its responses became weaker, despite an increase in the animals overall attentional intensity. This strong interaction between attentional selectivity and intensity could be identified in single trial spike trains. A simple divisive normalization of spatially distributed attention performances can explain the interaction between attention components well at the single neuron level. The effects of attentional selectivity and attentional intensity on neuronal responses were the same regardless of whether the changes were motivated by reward or task difficulty. These results provide a detailed cellular-level mechanism of how fundamental components of attention integrate and affect sensory processing in varying motivational and stimulus contexts.

neuroscience↗

bioRxiv2021

Telmisartan restricts Chikungunya virus infection in vitro and in vivo through the AT1/ PPAR-γ/MAPKs pathways

Chikungunya virus (CHIKV) has re-emerged as a global public health threat. The inflammatory pathways of RAS and PPAR-{gamma} are usually involved in viral infections. Thus, Telmisartan (TM) with known capacity to block AT1 receptor and activate PPAR-{gamma}, was investigated against CHIKV. The anti-CHIKV effect of TM was investigated in vitro (Vero, RAW 264.7 cells and hPBMCs) and in vivo (C57BL/6 mice). TM was found to abrogate CHIKV infection efficiently (IC50 of 15.34-20.89{micro}M in the Vero and RAW 264.7 cells respectively). Viral RNA and proteins were reduced remarkably with the TM driven modulation of host m-TOR signaling. Additionally, TM interfered in the early and late stages of CHIKV life cycle with efficacy in both pre and post-treatment assay. Moreover, the agonist of AT1 receptor and antagonist of PPAR-{gamma} increased CHIKV infection suggesting TMs anti-viral potential by modulating host factors. Besides, reduced activation of all major MAPKs, NF-{kappa}B (p65) and cytokines by TM through the inflammatory axis supported the fact that the anti-CHIKV efficacy of TM is partly mediated through the AT1/PPAR-{gamma}/MAPKs pathways. Interestingly, at the human equivalent dose, TM abrogated CHIKV infection and inflammation significantly leading to reduced clinical score and complete survival of C57BL/6 mice. Additionally, TM reduced infection in hPBMC derived monocyte-macrophage populations in vitro. Hence, TM was found to reduce CHIKV infection by targeting both viral and host factors. Considering its safety and in vivo efficacy, it can be a suitable candidate in future for repurposing against CHIKV.

microbiology↗

bioRxiv2021

A local insulin reservoir ensures developmental progression in condition of nutrient shortage in Drosophila

Insulin/IGF signalling (IIS) controls many aspects of development and physiology. In Drosophila, a conserved family of insulin-like peptides (Ilp) is produced by brain neurosecretory cells and exerts systemic functions. Here, we describe the local uptake and storage of Ilps in the Corpora Cardiaca (CC), a group of alpha cell homolog that produces the glucagon-like hormone AKH. Dilp uptake relies on the expression of Impl2, an IGF-BP that accumulates in the CCs. During nutrient shortage, this specific reserve of Ilps is released and activates IIS in a paracrine manner in the prothoracic gland, securing accelerated entry into pupal development through the production of the steroid hormone ecdysone. We therefore uncover a sparing mechanism whereby local Ilp storage and release activates the production of steroids and ensures early developmental progression in adverse food conditions. Highlights- Dilps are uptaken by CC cells through the IGF-BP Imp-L2 - the CC-Dilp store is released upon nutrient shortage and activates IIS through CC projections on the PG - upon nutrient shortage, IIS activation in the PG ensures an accelerated transition from larval feeding stage to metamorphosis.

developmental biology↗