Biology subjects

Srinivasan, S.

Publications and source records attributed to Srinivasan, S..

At least 109 records · Page 6Linked to original sources

bioRxiv2022

Two unique biological response-modifier glucans beneficially regulating gut microbiota and faecal metabolome in a non-alcoholic steatohepatitis animal model, with potential for applications in human health and disease

ObjectiveThe gut microbiome and its metabolites, influenced by age and stress, reflect the metabolism and immune systems health. We assessed the gut microbiota and faecal metabolome in a Stelic Animal Model of non-alcoholic steatohepatitis (NASH). DesignThis model was subjected to the following treatments: reverse osmosis water, AFO-202, N-163, AFO-202+N-163, and telmisartan. Faecal samples were collected at 6 weeks and 9 weeks of age. The gut microbiome was analysed using 16S ribosomal RNA sequence acquired by next-generation sequencing and the faecal metabolome using gas chromatography-mass spectrometry. ResultsThe gut microbial diversity increased greatly in the AFO-202+N-163 group. Post-intervention, the abundance of Firmicutes decreased, while that of Bacteroides increased and was the highest in the AFO-202+N-163 group. The decrease in the Enterobacteria and other Firmicutes abundance and in the Turicibacter and Bilophila abundance was the highest in the AFO-202 and N-163 groups, respectively. The Lactobacillus abundance increased the most in the AFO-202+N-163 group. The faecal metabolites spermidine and tryptophan, beneficial against inflammation and NASH, respectively, were greatly increased in the N-163 group. Succinic acid, beneficial in neurodevelopmental and neurodegenerative diseases, increased in the AFO-202 group. Decrease in fructose was the highest in the AFO-202 group. Leucine and phenylalanine decreased, whereas ornithine, which is beneficial against chronic immune-metabolic-inflammatory pathologies, increased in the AFO-202+N-163 group. ConclusionAFO-202 treatment in mice is beneficial against neurodevelopmental and neurodegenerative diseases and has prophylactic potential against metabolic conditions. N-163 treatment has anti-inflammatory effects against organ fibrosis and neuroinflammatory conditions. In combination, they present anticancer activity. Key messagesO_LIThe influence of gut microbiome on fecal metabolome and their association to several diseases is already known. C_LIO_LIThis study proves the efficacy of 1,3-1,6 beta glucans with pre-biotic potentials, beneficially influencing both gut microbiome and metabolome. C_LIO_LIThese results recommends for an in-depth exploration of relationship among pre-biotics, gut microbiome and gut-multi-organ axes on the fundamentals of disease onset. C_LIO_LIHidden prophylactic and therapeutic solutions to non-contagious diseases with Aureobasidium pullulans produced 1,3-1,6 beta glucans may be unveiled. C_LI

microbiology↗

bioRxiv2021

Ligand-induced transmembrane conformational coupling in monomeric EGFR

Single pass cell surface receptors regulate cellular processes by transmitting ligand-encoded signals across the plasma membrane via changes to their extracellular and intracellular conformations. While receptor-receptor interactions are established as key aspects of transmembrane signaling, the contribution from the single helix of a monomeric receptor has been challenging to isolate due to the complexity and ligand-dependence of the receptor-receptor interactions. By combining membrane nanodiscs produced wtih cell-free expression, single-molecule Forster Resonance Energy Transfer measurements, and molecular dynamics simulations, we report that ligand binding induces intracellular conformational changes within monomeric, full-length epidermal growth factor receptor (EGFR). Our observations establish the existence of extracellular/intracellular conformational coupling within a single receptor molecule. We implicate a series of electrostatic interactions in the conformational coupling and find the coupling is inhibited by targeted therapeutics and mutations that also inhibit phosphorylation in cells. Collectively, these results introduce a facile mechanism to link the extracellular and intracellular regions through the single transmembrane helix of monomeric EGFR, and raise the possibility that intramolecular transmembrane conformational changes are common to single-pass membrane proteins.

biophysics↗

bioRxiv2021

A basement membrane discovery pipeline uncovers network complexity, new regulators, and human disease associations

Basement membranes (BMs) are ubiquitous extracellular matrices whose composition remains elusive, limiting our understanding of BM regulation and function. By developing a bioinformatic and in vivo discovery pipeline, we define a network of 222 human proteins localized to BMs. Network analysis and screening in C. elegans and zebrafish identified new BM regulators, including ADAMTS, ROBO, and TGF{beta}. More than 100 BM-network genes associate with human phenotypes and by screening 63,039 genomes from families with rare disorders, we discovered loss-of-function variants in LAMA5, MPZL2, and MATN2, and show they regulate BM composition and function. This cross-disciplinary study establishes the immense complexity and role of BMs in human health.

cell biology↗

bioRxiv2021

A Comparative Genome-wide Transcriptome Analysis of Glucocorticoid Responder and Non-Responder Primary Human Trabecular Meshwork Cells

The genome-wide gene expression analysis of primary human trabecular meshwork (HTM) cells with known glucocorticoid (GC) responsiveness was not reported earlier. Therefore, the purpose of this study was to investigate genes and pathways involved in the GC responsiveness in human trabecular meshwork (HTM) cells using RNA sequencing. A perfusion cultured human anterior segment ex vivo model was utilized to identify the induction of GC-induced ocular hypertension in one eye of a paired eyes after dexamethasone treatment based on the maximum intraocular pressure response and in the contralateral eye, HTM cells were isolated to classify GC-responder and non-responder cells. Some previously reported and unique genes and their associated pathways were identified in HTM cells in response to dexamethasone treatment versus vehicle control and more significantly in GC-responder and non-responder cells. This study will open up the possibility of identifying suitable molecular targets which have the potential to treat GC-induced ocular hypertension/glaucoma.

genomics↗

bioRxiv2021

The genome trilogy of Anopheles stephensi, an urban malaria vector, reveals structure of a locus associated with adaptation to environmental heterogeneity

BackgroundAnopheles stephensi is the most menacing malaria vector to watch for in newly urbanizing parts of the world. The fitness is reported to be a direct consequence of the vector adapting to laying eggs in over-head water tanks with street-side water puddles polluted by oil and sewage. Large frequent inversions of malaria vectors are implicated in adaptation. ResultsWe report the assembly of a strain of An. stephensi of the type-form, collected from a construction site from Chennai (IndCh) in 2016. The genome completes the trilogy with respect to a 16 Mbp inversion (2Rb) in An. stephensi associated with adaptation to environmental heterogeneity. Comparative genome analysis revealed breakpoint structure and allowed extraction of 22,650 segregating SNPs for typing this inversion. Using whole genome sequencing of 82 individual mosquitoes, we conclude that one third of both wild and laboratory populations maintain heterozygous genotype of 2Rb. The large number of SNPs are tailored to assign inversion genotype directly from 1740 exonic SNPs 80% of which are expressed in various developmental stages. ConclusionsThe genome trilogy approach accelerates study of fine structure and typing of important inversions in malaria vectors putting the genome resources for the much understudied An. stephensi, on par with the extensively studied malaria vector, Anopheles gambiae. We argue that the IndCh genome is relevant for field translation work compared to those reported earlier by showing that individuals from diverse populations cluster with IndCh pointing to significant commerce between cities, perhaps, allowing for survival of the fittest strain.

genomics↗

bioRxiv2021

End-to-end computational approach to the design of RNA biosensors for miRNA biomarkers of cervical cancer

Cervical cancer is a global public health subject as it affects women in the reproductive ages, and accounts for the second largest burden among cancer patients worldwide with an unforgiving 50% mortality rate. Poor awareness and access to effective diagnosis have led to this enormous disease burden, calling for point-of-care, minimally invasive diagnosis methods. Here, an end-to-end quantitative approach for a new kind of diagnosis has been developed, comprising identification of optimal biomarkers, design of the sensor, and simulation of the diagnostic circuit. Using miRNA expression data in the public domain, we identified circulating miRNA biomarkers specific to cervical cancer using multi-tier screening. Synthetic riboregulators called toehold switches specific for the biomarker panel were then designed. To predict the dynamic range of toehold switches for use in genetic circuits as biosensors, we developed a generic grammar of these switches, and built a multivariate linear regression model using thermodynamic features derived from RNA secondary structure and interaction. The model yielded predictions of toehold efficacy with an adjusted R2 = 0.59. Reaction kinetics modelling was performed to predict the sensitivity of the second-generation toehold switches to the miRNA biomarkers. Simulations showed a linear response between 10nM and 100nM before saturation. Our study demonstrates an end-to-end workflow for the efficient design of genetic circuits geared towards the effective detection of unique genomic signatures that would be increasingly important in todays world. The approach has the potential to direct experimental efforts and minimise costs. All resources including the machine learning toolkit, reaction kinetics simulation, designed toehold sequences, genetic circuits, data and sbml files for replicating and utilizing our study are provided open-source with the iGEM Foundation (https://github.com/igem2019) under GNU GPLv3 licence.

synthetic biology↗

bioRxiv2021

Induced ligno-suberin vascular coating and tyramine-derived hydroxycinnamic acid amides restrict Ralstonia solanacearum colonization in resistant tomato roots

The soil borne pathogen Ralstonia solanacearum is the causing agent of bacterial wilt, a devastating disease affecting major agricultural crops. R. solanacearum enters plants through the roots and reaches the vasculature, causing rapid wilting. We recently showed that tomato varieties resistant to bacterial wilt restrict bacterial movement in the plant. In the present work we go a step forward by identifying the physico-chemical nature of the barriers induced in resistant tomato roots in response to R. solanacearum. We describe that resistant tomato specifically responds to infection by assembling de novo a structural barrier at the vasculature formed by a ligno-suberin coating and tyramine-derived hydroxycinnamic acid amides (HCAAs). On the contrary, susceptible tomato does not form these reinforcements in response to the pathogen but instead displays lignin structural changes compatible with its degradation. Further, we show that overexpressing genes of the ligno-suberin pathway in a commercial susceptible variety of tomato restricts R. solanacearum movement inside the plant and slows disease progression, enhancing resistance to the pathogen. We thus propose that the induced barrier in resistant plants does not only restrict the movement of the pathogen, but may also prevent cell wall degradation by the pathogen and confer anti-microbial properties.

plant biology↗

bioRxiv2021

Enrichment analysis of GWAS data in autoimmunity delineates the multiple sclerosis-Epstein Barr virus association

We exploited genetic information to assess non-genetic influences in autoimmunity. We isolated gene modules whose products physically interact with environmental exposures related to autoimmunity, and analyzed their nominal statistical evidence of association with autoimmune and non-autoimmune diseases in genome-wide association studies (GWAS) data. Epstein Barr virus (EBV) and other Herpesviruses interactomes emerged as specifically associated with multiple sclerosis (MS), possibly under common regulatory mechanisms. Analyses of MS blood and brain transcriptomes, cytofluorimetric studies of endogenous EBV-infected lymphoblastoid lines, and lesion immunohistochemistry, confirmed a dysregulation of MS-associated EBV interactors, suggesting their contribution to CD40 signaling alterations in MS. These interactors resulted enriched in modules from inherited axonopathies-causing genes, supporting a link between EBV and neurodegeneration in MS, in accord with the observed transcriptomic dysregulations in MS brains. They were also enriched with top-ranked pharmaceutical targets prioritized on a genetic basis. This study delineates a disease-specific influence of herpesviruses on MS biology.

neuroscience↗

bioRxiv2021

Invivo and systematic analysis of random multigenic deletions associated with human diseases during epithelial morphogenesis using Drosophila

Random loss of multigenic loci on chromosomes, a crucial drive for evolution, occurs frequently in all living organisms. Analysis of such chromosomal disruption and understanding the consequences of their impact on the growth and development of multicellular organisms is challenging. In this report, we have addressed this issue using invivo mosaic analysis of deficiency lines in Drosophila. Genes on fly deficiency lines were compared with human orthologs for their implications in disease development during cytoskeletal processes and epithelial morphogenesis. The cytoskeletal phenotypes from the fly has been utilized to predict the function of human orthologs. In addition, as these Drosophila deficiency lines are equivalent to human microdeletions, based on the clonal behaviour and phenotypes generated, a systematic analysis has been carried out to establish the critical loci that correspond to Microdeletion Syndromes and Mendelian Disorders in humans. Further we have drawn the synteny that exists between these chromosomes and have identified critical region corresponding to defects. A few potential candidates that might have an implication in epithelial morphogenesis are also identified.

genetics↗

bioRxiv2020

SQ3370 Activates Cytotoxic Drug via Click Chemistry at Tumor and Elicits Sustained Responses in Injected & Non-injected Lesions

While systemic immuno-oncology therapies have shown remarkable success, only a limited subset of patients benefit from them. Our Click Activated Protodrugs Against Cancer (CAPAC) Platform is a click chemistry-based approach that activates cancer drugs at a specific tumor with minimal systemic toxicity. CAPAC Platform is agnostic to tumor characteristics that can vary across patients and hence applicable to several types of tumors. We describe the benefits of SQ3370 (lead candidate of CAPAC) to achieve systemic anti-tumor responses in mice bearing two tumors. SQ3370 consists of a biopolymer, injected in a single lesion, followed by systemic doses of an attenuated protodrug of doxorubicin (Dox). SQ3370 was well-tolerated at 5.9-times the maximum dose of conventional Dox, increased survival by 63% and induced a systemic antitumor response against injected and non-injected lesions. The sustained anti-tumor response also correlated with immune activation measured at both lesions. SQ3370 could potentially benefit patients with micro-metastatic lesions.

bioengineering↗

bioRxiv2020

Diversity Across the Pancreatic Ductal Adenocarcinoma Disease Spectrum Revealed by Network-Anchored Functional Genomics

Cancers are highly complex ecosystems composed of molecularly distinct sub-populations of tumor cells, each exhibiting a unique spectrum of genetic features and phenotypes, and embedded within a complex organ context. To substantially improve clinical outcomes, there is a need to comprehensively define inter- and intra-tumor phenotypic diversity, as well as to understand the genetic dependencies that underlie discrete molecular subpopulations. To this end, we integrated CRISPR-based co-dependency annotations with a tissue-specific co-expression network developed from patient-derived models to establish CoDEX, a framework to quantitatively associate gene-cluster patterns with genetic vulnerabilities in pancreatic ductal adenocarcinoma (PDAC). Using CoDEX, we defined multiple prominent anticorrelated gene-cluster signatures and specific pathway dependencies, both across genetically distinct PDAC models and intratumorally at the single-cell level. Of these, one differential signature recapitulated the characteristics of classical and basal-like PDAC molecular subtypes on a continuous scale. Anchoring genetic dependencies identified through functional genomics within the gene-cluster signature defined fundamental vulnerabilities associated with transcriptomic signatures of PDAC subtypes. Subtype-associated dependencies were validated by feature-barcoded CRISPR knockout of prioritized basal-like-associated genetic vulnerabilities (SMAD4, ILK, and ZEB1) followed by scRNAseq in multiple PDAC models. Silencing of these genes resulted in a significant and directional clonal shift toward the classical-like signature of more indolent tumors. These results validate CoDEX as a novel, quantitative approach to identify specific genetic dependencies within defined molecular contexts that may guide clinical positioning of targeted therapeutics.

cancer biology↗

bioRxiv2020

Limited window for donation of convalescent plasma with high live-virus neutralizing antibodies for COVID-19 immunotherapy

The optimal timeframe for donating convalescent plasma to be used for COVID-19 immunotherapy is unknown. To address this important knowledge deficit, we determined in vitro live-virus neutralizing capacity and persistence of IgM and IgG antibody responses against the receptor-binding domain and S1 ectodomain of the SARS-CoV-2 spike glycoprotein in 540 convalescent plasma samples obtained from 175 COVID-19 plasma donors for up to 142 days post-symptom onset. Robust IgM, IgG, and viral neutralization responses to SARS-CoV-2 persist, in the aggregate, for at least 100 days post-symptom onset. However, a notable acceleration in decline in virus neutralization titers [≥]160, a value suitable for convalescent plasma therapy, was observed starting 60 days after first symptom onset. Together, these findings better define the optimal window for donating convalescent plasma useful for immunotherapy of COVID-19 patients and reveal important predictors of an ideal plasma donor, including age and COVID-19 disease severity score. One Sentence SummaryEvaluation of SARS-CoV-2 anti-spike protein IgM, IgG, and live-virus neutralizing titer profiles reveals that the optimal window for donating convalescent plasma for use in immunotherapy is within the first 60 days of symptom onset.

immunology↗

bioRxiv2020

Global transcriptional regulators fine-tune the translational and metabolic machinery in Escherichia coli under anaerobic fermentation

Complex regulatory interactions between genetic and metabolic networks together confer robustness against external and internal perturbations in an organism such as Escherichia coli. In balanced exponential growth, this robustness is attributed to cost-effective metabolism by means of efficient resource allocation coordinated by the interplay of global transcriptional regulators with growth-rate dependent machinery. Here, we reappraise the role of global transcriptional regulators FNR, ArcA and IHF, integral to sustaining proteome-efficiency in anaerobic fermentative conditions, fundamental for optimal growth of E. coli. We reveal at the transcriptome and metabolome level, that absence of these global regulators ensued a disruption of nitrogen homeostasis, overexpression of otherwise unnecessary or hedging genes and impairment in core bottleneck steps and amino acid metabolism. Notably, our findings emphasize their importance in optimizing the metabolic proteome resources essential for rapid exponential growth. Consequentially, the perturbations in the metabolic proteome as a result of deletion of global regulators unbalances the ribosomal proteome share imposing a high translation program, though at the expense of lowered efficiency. We illustrate that disruption of this inherent trade-off between metabolic and ribosomal proteomic investment eventually culminate to lowered growth rates. Despite no changes in gene expression related to glucose import, our findings elucidate that the accumulations of intracellular metabolites directly modulated by growth rate, negatively impacts the glucose uptake. Our results employing the proteome allocation theory and quantitative experimental measurements, suffices to explain the physiological consequences of altered translational and metabolic efficiency in the cell, driven by the loss of these global regulators.

systems biology↗

bioRxiv2020

Classification of grain amaranths using chromosome-level genome assembly of ramdana, A. hypochondriacus

In the age of genomics-based crop improvement, a high-quality genome of a local landrace adapted to the local environmental conditions is critically important. Grain amaranths produce highly nutritional grains with a multitude of desirable properties including C4 photosynthesis highly sought-after in other crops. For improving the agronomic traits of grain amaranth and for the transfer of desirable traits to dicot crops, a reference genome of a local landrace is necessary. Towards this end, our lab had initiated sequencing the genome of Amaranthus (A.) hypochondriacus (A.hyp_K_white) and had reported a draft genome in 2014. We selected this landrace because it is well adapted for cultivation in India during the last century and is currently a candidate for TILLING-based crop improvement. More recently, a high-quality chromosome-level assembly of A. hypochondriacus (PI558499, Plainsman) was reported. Here, we report a chromosome-level assembly of A.hyp_K_white (AhKP) using low-coverage PacBio reads, contigs from the reported draft genome of A.hyp_K_white, raw HiC data and reference genome of Plainsman. The placement of A.hyp_K_white on the phylogenetic tree of grain amaranths of known accessions clearly suggests that A.hyp_K_white is genetically distal from Plainsman and is most closely related to the accession PI619259 from Nepal (Ramdana). Furthermore, the classification of another accession, Suvarna, adapted to the local environment and selected for yield and other desirable traits, is clearly A. cruentus. A classification based on hundreds of thousands of SNPs validated taxonomy-based classification for a majority of the accessions providing the opportunity for reclassification of a few.

genomics↗

bioRxiv2020

Activation of the Crtc2/Creb1 transcriptional network in skeletal muscle enhances weight loss during intermittent fasting

The Creb-Regulated Transcriptional Coactivator (Crtc) family of transcriptional coregulators drive Creb1-mediated transcription effects on metabolism in many tissues, but the in vivo effects of Crtc2/Creb1 transcription on skeletal muscle metabolism are not known. Skeletal muscle-specific overexpression of Crtc2 (Crtc 2 mice) induced greater mitochondrial activity, metabolic flux capacity for both carbohydrates and fats, improved glucose tolerance and insulin sensitivity, and increased oxidative capacity, supported by upregulation of key metabolic genes. Crtc2 overexpression led to greater weight loss during alternate day fasting (ADF), selective loss of fat rather than lean mass, supported by maintenance of higher energy expenditure during the fast. ADF downregulated most of the mitochondrial electron transport genes, and other regulators of mitochondrial function, that were substantially reversed by Crtc2-driven transcription. Glucocorticoids acted with AMPK to drive atrophy and mitophagy, which was reversed by Crtc2/Creb1 signaling. Crtc2/Creb1-mediated signaling coordinates metabolic adaptations in skeletal muscle that explain how Crtc2/Creb1 regulates metabolism and weight loss.

physiology↗

bioRxiv2020

Elucidating the regulatory role of CRP in coordinating protein biosynthesis machinery with metabolism that defines growth optimality in Escherichia coli

Evolution entails the orchestration of cellular resources together with mutations to achieve fitter phenotypes. Here, we determined the system-wide pleiotropic effects that redress the significant perturbations caused by the deletion of global transcriptional regulator CRP in Escherichia coli when evolved in the presence of glucose. We elucidated that absence of CRP results in alterations in key metabolic pathways instrumental for the precise functioning of protein biosynthesis machinery that subsequently corroborated with intracellular metabolite profiles. Apart from acquiring mutations in the promoter of glucose transporter ptsG, the evolved populations recovered the metabolic pathways to their pre-perturbed state with amelioration of protein biosynthesis machinery coupled with fine-tuned proteome re-allocation that enabled growth recovery. However, ineffective utilization of carbon towards biomass as perceived from ATP maintenance flux and costly amino acid accumulations poses a limitation. Overall, we comprehensively illustrate the genetic and metabolic adjustments underlying adaptive evolvability, fundamental for understanding the growth physiology.

systems biology↗

bioRxiv2020

Chemical Systems Biology Reveals Mechanisms of Dissociated Glucocorticoid Receptor Signaling

Glucocorticoids display remarkable anti-inflammatory activity, but their use is limited by on-target adverse effects including insulin resistance and skeletal muscle atrophy. We used a chemical systems biology approach, Ligand Class Analysis (LCA), to examine ligands designed to modulate glucocorticoid receptor activity through distinct structural mechanisms. These ligands displayed diverse activity profiles, providing the variance required to identify target genes and coregulator interactions that were highly predictive of their effects on myocyte glucose disposal and protein balance. Their anti-inflammatory effects were linked to glucose disposal but not muscle atrophy. This approach also predicted selective modulation in vivo, identifying compounds that were muscle sparing or anabolic for protein balance and mitochondrial potential. LCA defined the mechanistic links between the ligand-receptor interface and ligand-driven physiological outcomes, a general approach that can be applied to any ligand-regulated allosteric signaling system.

pharmacology and toxicology↗

bioRxiv2020

Relationship between Anti-Spike Protein Antibody Titers and SARS-CoV-2 In Vitro Virus Neutralization in Convalescent Plasma

Newly emerged pathogens such as SARS-CoV-2 highlight the urgent need for assays that detect levels of neutralizing antibodies that may be protective. We studied the relationship between anti-spike ectodomain (ECD) and anti-receptor binding domain (RBD) IgG titers, and SARS-CoV-2 virus neutralization (VN) titers generated by two different in vitro assays using convalescent plasma samples obtained from 68 COVID-19 patients, including 13 who donated plasma multiple times. Only 23% (16/68) of donors had been hospitalized. We also studied 16 samples from subjects found to have anti-spike protein IgG during surveillance screening of asymptomatic individuals. We report a strong positive correlation between both plasma anti-RBD and anti-ECD IgG titers, and in vitro VN titer. Anti-RBD plasma IgG correlated slightly better than anti-ECD IgG titer with VN titer. The probability of a VN titer [≥]160 was 80% or greater with anti-RBD or anti-ECD titers of [≥]1:1350. Thirty-seven percent (25/68) of convalescent plasma donors lacked VN titers [≥]160, the FDA-recommended level for convalescent plasma used for COVID-19 treatment. Dyspnea, hospitalization, and disease severity were significantly associated with higher VN titer. Frequent donation of convalescent plasma did not significantly decrease either VN or IgG titers. Analysis of 2,814 asymptomatic adults found 27 individuals with anti-RBD or anti-ECD IgG titers of [≥]1:1350, and evidence of VN [≥]1:160. Taken together, we conclude that anti-RBD or anti-ECD IgG titers can serve as a surrogate for VN titers to identify suitable plasma donors. Plasma anti-RBD or anti-ECD titer of [≥]1:1350 may provide critical information about protection against COVID-19 disease.

immunology↗