Biology subjects

Sehgal, D.

Publications and source records attributed to Sehgal, D..

4 recordsLinked to original sources

bioRxiv2025

Microbial Scl1 Activates TGFBR1 receptor kinase signalling to Drive Fibrosis-Inflammation Axis in Alcohol-Associated Liver Disease

Background and AimsAlcohol consumption alters gut microbiota, which can affect metabolism, immune regulation, and signalling pathways and lead to alcohol-associated liver disease (ALD). We investigated how alcohol-associated gut microbiota (AGMs) modulate liver kinome signalling to drive inflammation and fibrosis in ALD. MethodLiver kinome and metaproteome changes were studied in rats (n=6/group) colonized with stool of severe alcohol-related hepatitis (SAH) patients (SAH[->]healthy-rats) or healthy human donors (HD[->]ALD-rats). AGM-associated liver kinome changes were cross-correlated with bacterial genera. A bacterial protein; Streptococcal collagen-like protein 1 (Scl1) was identified with affinity for TGF{beta}R1. This was validated by molecular docking and immunoprecipitation-LCMS assay. Expression of Streptococcus pneumonia and pyogenes was done in stool of SAH patients (n=10). Also, Scl1 was quantified in patient stool (n=24) and liver tissue (n=19) samples. Validation was performed by assessing Scl1 level in plasma and Streptococcus level in stool samples before and after fecal microbiota transplantation (FMT) in SAH patients. ResultsStool metaproteomics showed significant increase in 10 bacterial genera (Streptococcus, Staphylococcus, and Clostridium) in SAH[->]Healthy-rats, mirroring changes seen in ALD-rats (FC>1.5, p<0.05). Clusters of Orthologous Groups analysis indicated increased post-translational modifications (PTMs) and decreased lipid metabolism in ALD-rats and SAH[->]Healthy-rats. Liver kinome profiling showed 85 upregulated kinases in SAH[->]Healthy-rats, with 34 overlapping with ALD-rats, associated with inflammation (Mapk14, Map3k10 and others), fibrosis (Tgfbr1, Igf1r, and others), lipid metabolism (Cdk14, Cdk18) and regeneration (Met, Bmpr1a and others). FMT from healthy human-donors to ALD-rats reversed the expression of Streptococcus (10-fold), Staphylococcus (3-fold), and Clostridium (5-fold), along with 18 kinases associated with inflammation (Btk, Camk4, Nuak1) and fibrosis (Tgfbr1, Col4a1, Fgfr2 and others). Strong association (r{superscript 2}>0.9, p<0.05) was seen between Streptococcus abundance and fibrosis and inflammation-related kinases. Level of Scl1 was significantly high in SAH and ALD-rat stool samples (FC>2, p<0.05). It showed strong affinity for TGF{beta}R1, as validated by molecular docking (>86%confidence) and immunoprecipitation assays (>100FC,p<0.05), indicating it as a potential ligand for TGF{beta}R1. Concordantly, expression of Scl1 was highest amongst all the known ligands for TGF{beta}R1 (p<0.05) suggesting Scl1 is a major contributor for TGF{beta}R1 activation and its downstream signalling in these patients. Following fecal microbiota transplantation, expression of Scl1 in plasma and Streptococcus levels in stool were significantly reduced by 2.1-folds and 1.9 folds respectively in SAH patients. Further, Scl1 levels SAH plasma is capable of predicting poor therapeutic response and 30-day mortality with high accuracy (AUC=0.92, cutoff >70 normalized abundance). ConclusionAlcohol induced gut dysbiosis alters the liver kinome, promoting inflammation, fibrosis, and lipid dysregulation. Streptococcal Scl1 is identified as a bacterial protein mimicking human collagen and capable of activating fibrotic signalling pathway through TGF{beta}R1in liver and is capable of predicting poor response in SAH. FMT from healthy donor restores microbial imbalance and harmful microbial-host interactions.

microbiology↗

bioRxiv2023

Interaction of SCoV-2 NSP7 or NSP8 alone may cause constriction of the RNA entry channel in NSP12: Implications for novel RdRp inhibitor drug discovery

RNA-dependent RNA polymerase (RdRP) is a critical component of the RNA virus life cycle, including SCoV-2. Among the Coronavirus-encoded proteins, non-structural protein 12 (NSP12) exhibits polymerase activity in collaboration with one unit of NSP7 and two units of NSP8, constituting the RdRp holoenzyme. While there is abundant information on SCoV-2 RdRp-mediated RNA replication, the influence of interplay among NSP12, NSP7, and NSP8 on template RNA binding and primer extension activity remains relatively unexplored and poorly understood. Here, we recreated a functional RdRp holoenzyme in vitro using recombinant SCoV-2 NSP12, NSP7, and NSP8, and established its functional activity. Subsequently, molecular interactions among the NSPs in the presence of a variety of templates and their effects on polymerase activity were studied, wherein we found that NSP12 alone exhibited notable polymerase activity that increased significantly in the presence of NSP7 and NSP8. However, this activity was completely shut down, and the template RNA-primer complex was detached from NSP12 when one of the two cofactors was present. Through computational analysis, we found that the template RNA entry channel was more constricted in the presence of one of the two cofactors, which was relatively more constricted in the presence of NSP8 compared to that in the presence of NSP7. In conclusion, we report that NSP7 and NSP8 together synergise to enhance the activity of NSP12, but antagonise when present alone. Our findings have implications for novel drug development, and compounds that obstruct the binding of NSP7 or NSP8 to NSP12 can have lethal effects on viral RNA replication.

molecular biology↗

bioRxiv2023

The International Weed Genomics Consortium: Community Resources for Weed Genomics Research

The International Weed Genomics Consortium is a collaborative group of researchers focused on developing genomic resources for the study of weedy plants. Weeds are attractive systems for basic and applied research due to their impacts on agricultural systems and capacity to swiftly adapt in response to anthropogenic selection pressures. Our goal is to use genomic information to develop sustainable and effective weed control methods and to provide insights about biotic and abiotic stress tolerance to assist crop breeding. Here, we outline resources under development by the consortium and highlight areas of research that will be impacted by these enabling resources.

genomics↗

bioRxiv2022

Allele mining, evolutionary genetic analysis of TaHKT1;5 gene and evaluation of salinity stress in selected lines of wheat.

This study reports the novel allelic diversity in HKT 1;5 gene (High Affinity Potassium Transporter) in bread wheat and its phylogenetic relationship among the paralogs/orthologs of in Triticum aestivum and its wild relatives. HKT 1;5 gene is a known and pivotal gene associated with the salinity tolerance in plants upon the discrimination of K+ over Na+ in leaves without change in Na+ concentration in root. This gene was sequenced in a diverse collection of bread wheat, durum wheat, wild relatives, and ditelosomic lines. Sequence analysis in bread wheat led to the identification of four alleles, which could be distinguished by number of SNPs. Sequence comparison between monocot bread wheat and dicot Arabidopsis thaliana revealed that the HKT1;5 gene is conserved at level of exonic regions; however, the presence of transposable elements especially in intronic regions is further intriguing towards evolutionary relatedness. Two paralogous or major alleles observed in Triticum monoccum and Aegilops tauschii were further categorized as sub-alleles based on their SNPs comparison. This gene was absent in T. urartu in accordance with existing evidence, while it was found in A. speltoides (an allelic variant) with a few base pairs insertion in the exon1 region causing a frameshift mutation with an altered amino acids and genomic database mining unveiled additional alleles in this species. Ditelosomic lines with 4DL and 4DS chromosomes revealed a higher similarity with bread and durum wheat respectively. Phylogenetic studies of HKT1;5 orthologs from different Poaceae species revealed the occurrence of five different ortholog groups with taxonomic consistency. Phenotyping based salinity stress experiment distinguished the unknown lines for salinity tolerance and sensitiveness in comparison with known reference lines and possible allelic comparison was made. The salinity stress analysis further revealed that some known drought/heat tolerance lines showed slightly better salinity tolerance with mean values and variability of traits than known saline tolerant wheat line at controlled ambient.

genetics↗