Biology subjects

Mohan, M.

Publications and source records attributed to Mohan, M..

3 recordsLinked to original sources

bioRxiv2021

Elucidation of the molecular interactions that enable stable interaction between HIV protease inhibitor ritonavir and human DNA repair enzyme ALKBH2: a molecular dynamics simulation study

The human DNA repair enzyme AlkB homologue-2 and 3 (ALKBH2 and ALKKBH3) repairs methyl adducts from genomic DNA. Overexpression of ALKBH2 and ALKBH3 has been implicated in both tumorigenesis and chemotherapy resistance in some cancers, including glioblastoma and renal cancer rendering it a potential therapeutic target and a diagnostic marker. However, no inhibitor is available against these important DNA repair proteins. Intending to repurpose a drug as an inhibitor of ALKBH2/ALKBH3, we performed in silico evaluation of HIV protease inhibitors and identified Ritonavir as an ALKBH2-interacting molecule. Using molecular dynamics simulation, we elucidated the molecular details of Ritonavir-ALKBH2 interaction. The present work highlights that Ritonavir might be used to target the ALKBH2-mediated DNA alkylation repair.

bioinformatics↗

bioRxiv2020

Insulin inhibits protein phosphatase 2A to impair β-adrenergic receptor function

Insulin impairs {beta}2-adrenergic receptor ({beta}2AR) function through G protein-coupled receptor kinase 2 (GRK2) by phosphorylation but less is known about dephosphorylation mechanisms mediated by protein phosphatase 2A (PP2A). Pharmacologic or genetic inhibition of phosphoinositide 3-kinase {gamma} (PI3K{gamma}) unexpectedly resulted in significant reduction of insulin-mediated {beta}2AR phosphorylation. Interestingly, {beta}2AR-associated phosphatase activity was inhibited by insulin but was reversed by knock-down of PI3K{gamma} showing negative regulation of PP2A by PI3K{gamma}. Co-immunoprecipitation and surface plasmon resonance studies using purified proteins showed that GRK2 and PI3K{gamma} form a complex and could be recruited to {beta}2ARs as GRK2 interacts with insulin receptor substrate following insulin treatment. Consistently, {beta}-blocker pretreatment did not reduce insulin-mediated {beta}2AR phosphorylation indicating agonist- and G{beta}{gamma}-independent non-canonical regulation of receptor function. Mechanistically, PI3K{gamma} inhibits PP2A activity at the {beta}AR complex by phosphorylating an intracellular inhibitor of PP2A (I2PP2A). Knock-down or CRISPR ablation of endogenous I2PP2A unlocked PP2A inhibition mediating {beta}2AR dephosphorylation showing an unappreciated acute regulation of PP2A in mediating insulin-{beta}2AR cross-talk. SummaryInsulin impairs {beta}2-adrenergic receptor ({beta}2AR) function through G protein-coupled receptor kinase 2 (GRK2). We show that insulin simultaneously inhibits protein phosphatase 2A (PP2A) sustaining {beta}2AR functional impairment. Unexpectedly, releasing PP2A inhibition by PI3K{gamma} preserves {beta}2AR function despite intact insulin-driven GRK2-mechanisms.

biochemistry↗

bioRxiv2020

Initial insights into the genetic epidemiology of SARS-CoV-2 isolates from Kerala suggest local spread from limited introductions

Coronavirus disease 2019 (COVID-19) rapidly spread from a city in China to almost every country in the world, affecting millions of individuals. Genomic approaches have been extensively used to understand the evolution and epidemiology of SARS-CoV-2 across the world. Kerala is a unique state in India well connected with the rest of the world through a large number of expatriates, trade, and tourism. The first case of COVID-19 in India was reported in Kerala in January 2020, during the initial days of the pandemic. The rapid increase in the COVID-19 cases in the state of Kerala has necessitated the understanding of the genetic epidemiology of circulating virus, evolution, and mutations in SARS-CoV-2. We sequenced a total of 200 samples from patients at a tertiary hospital in Kerala using COVIDSeq protocol at a mean coverage of 7,755X. The analysis identified 166 unique high-quality variants encompassing 4 novel variants and 89 new variants identified for the first time in SARS-CoV-2 samples isolated from India. Phylogenetic and haplotype analysis revealed that the circulating population of the virus was dominated (94.6% of genomes) by three distinct introductions followed by local spread, apart from identifying polytomies suggesting recent outbreaks. The genomes formed a monophyletic distribution exclusively mapping to the A2a clade. Further analysis of the functional variants revealed two variants in the S gene of the virus reportedly associated with increased infectivity and 5 variants that mapped to five primer/probe binding sites that could potentially compromise the efficacy of RT-PCR detection. To the best of our knowledge, this is the first and most comprehensive report of genetic epidemiology and evolution of SARS-CoV-2 isolates from Kerala.

genomics↗