Biology subjects

Jana, I. D.

Publications and source records attributed to Jana, I. D..

4 recordsLinked to original sources

bioRxiv2025

Influenza virus recruits PKCa-MEK1-ERK2 complex to regulate nuclear export of viral ribonucleoproteins and promote virus replication.

Host kinases had long been implicated in regulating various steps of influenza virus replication cycle. Previous studies showed that the protein kinase C (PKC) activated mitogen activated protein kinase (MEK)/ extracellular signal-regulated kinase (ERK) cascade promotes nuclear export of viral ribonucleoprotein complexes (RNPs), by triggering phosphorylation of viral nucleoprotein (NP), the major constituent of RNPs. But, the molecular mechanism by which PKC coordinates with specific members of the MAPK pathway to regulate NP phosphorylation remained obscure. Additionally, the molecular interactions of these kinases with NP and the spatiotemporal dynamics of such interactions have never been investigated. Here we unravel the existence of a tripartite PKC-MEK1-ERK2 complex that associates with influenza virus NP and mediates its phosphorylation during the course of infection. Using an analogue sensitive kinase, we show that ERK2 can directly phosphorylate NP at specific serine-threonine residues, which promote vRNP nuclear export and are indispensable for virus propagation. PKC not only activates the MAP kinase, but acts as a scaffold for mediating stable interactions between MEK1, ERK2 and NP, thereby forming an NP associated multi-kinase complex that facilitate its phosphorylation. This multiprotein complex localizes in the nucleus early during infection but into cytoplasm at later stages and overexpression of a dominant negative PKC blocks this complex formation, NP phosphorylation, vRNP export and progeny virus production. These data not only unravel a complex network of virus-host interactions supporting different influenza A and B virus replication, but also shade light upon an unexplored avenue of PKC mediated regulation MAPK pathway. SignificanceThe substrate specificity of kinases is the key for precise regulation of various signaling cascades and can be governed by direct kinase-substrate interaction or indirect interaction mediated through scaffolding or anchoring proteins. This study shows how influenza virus exploit a well-known cellular kinase, PKC, as a scaffold protein to activate and recruit other cellular kinases, MEK1 and ERK2, upon viral replication machinery, RNPs. This RNP associated multi-kinase complex facilitates ERK2 mediated phosphorylation of viral NP protein, which regulates RNP nuclear export and ultimately the production of new virion particles. This work elucidates an unconventional mechanism of kinase-substrate interaction which is critical for influenza virus replication and hence paves the way towards the development of novel host directed anti-influenza therapy.

molecular biology↗

bioRxiv2024

Identification of novel thiazole derivatives as flaviviral protease inhibitors against DENV and JEV

Flaviviruses are the causative agents of viral hemorrhagic fever (VHF) globally and have demonstrated the capacity to result in fatal outcomes if not managed effectively. Among different types of flaviviruses, dengue (DENV) and Japanese encephalitis (JEV) are the most common in tropical and subtropical countries. Given the scarcity of effective vaccines against flaviviral infections, small molecule agents that target crucial viral proteins emerge as the sole feasible option. This study outlines the synthesis of novel thiazole compounds as flavivirus NS2B-NS3 protease inhibitor and characterization of their antiviral activity against DENV and JEV. We synthesized a heterocyclic template derived from a substrate-based retrotripeptide dengue protease inhibitor, leading to forty-eight thiazole derivatives. Two compounds demonstrated significant inhibition of dengue virus protease activity in vitro. Comprehensive characterization of these two compounds was conducted through biochemical assay which revealed an uncompetitive mode of inhibition. Subsequent cell-based assays using Dengue and Japanese encephalitis viruses as representatives Flaviviruses imparted the potential of these compounds to block viral RNA synthesis, and viral replication. Finally time-course experiments unveiled that the two compounds impeded the accumulation of viral genomic RNA primarily at later stages of infection, aligning with their capacity to hinder NS2B-NS3 protease activity, polyprotein processing and viral genomic RNA replication. Together our work presents the development and validation of flavivirus protease inhibitors with therapeutic potential against Dengue and Japanese encephalitis virus.

microbiology↗

bioRxiv2022

Targeting an evolutionarily conserved "E-L-L" motif in the spike protein to develop a small molecule fusion inhibitor against SARS-CoV-2

As newer variants of SARS-CoV-2 continue to pose major threats to global human health and economy, identifying novel druggable antiviral targets is the key towards sustenance. Here, we identify an evolutionary conserved "E-L-L" motif present within the HR2 domain of all human and non-human coronavirus spike (S) proteins that play a crucial role in stabilizing the post-fusion six-helix bundle (6-HB) structure and thus, fusion-mediated viral entry. Mutations within this motif reduce the fusogenicity of the S protein without affecting its stability or membrane localization. We found that posaconazole, an FDA-approved drug, binds to this "E-L-L" motif resulting in effective inhibition of SARS-CoV-2 infection in cells. While posaconazole exhibits high efficacy towards blocking S protein-mediated viral entry, mutations within the "E-L-L" motif rendered the protein completely resistant to the drug, establishing its specificity towards this motif. Our data demonstrate that posaconazole restricts early stages of infection through specific inhibition of membrane fusion and viral genome release into the host cell and is equally effective towards all major variants of concerns of SARS-CoV-2 including beta, kappa, delta, and omicron. Together, we show that this conserved essential "E-L-L" motif is an ideal target for the development of prophylactic and therapeutic interventions against SARS-CoV-2.

biochemistry↗

bioRxiv2020

Development of a copper-graphene nanocomposite based transparent coating with antiviral activity against influenza virus

Respiratory infections by RNA viruses are one of the major burdens upon global health and economy. Viruses like influenza or coronaviruses can be transmitted through respiratory droplets or contaminated surfaces. An effective antiviral coating can decrease the viability of the virus particles in the outside environment significantly, hence reducing their transmission rate. In this work, we have screened a series of nanoparticles and their composites for antiviral activity using Nano Luciferase based highly sensitive influenza A reporter virus. Using this screening system, we have identified copper-graphene (Cu-Gr) nanocomposite shows strong antiviral activity. Extensive material and biological characterization of the nanocomposite suggested a unique metal oxide embedded graphene sheet architecture that can inactivate the virion particles only within 30 minutes of pre-incubation and subsequently interferes with the entry of these virion particles into the host cell. This ultimately results in reduced viral gene expression, replication and production of progeny virus particles, slowing down the overall pace of progression of infection. Using PVA as a capping agent, we have been able to generate a Cu-Gr nanocomposite based highly transparent coating that retains its original antiviral activity in the solid form.

microbiology↗