Biology subjects

Karisetty, B. C.

Publications and source records attributed to Karisetty, B. C..

5 recordsLinked to original sources

bioRxiv2026

RSAD2/VIPERIN and CMPK2 Coordinate an Immunometabolic Response to Epstein-Barr Virus

Epstein-Barr Virus (EBV) infection and reactivation in B-lymphocytes is tightly regulated by host antiviral response genes. In the present study, we identify interferon stimulated genes RSAD2 (radical S-adenosyl methionine domain-containing 2) and CMPK2 (Cytidine/Uridine Monophosphate Kinase 2) as key modulators of EBV expression and cellular response during EBV infection and reactivation. EBV primary infection and reactivation lead to a coordinated up-regulation of RSAD2 and CMPK2. Depletion of RSAD2 reduced cell viability and limited EBV reactivation, while depletion of CMPK2 led to reactivation of EBV lytic gene expression during latency. Transcriptomic analysis revealed that RSAD2 and CMPK2 have overlapping functions in regulating IFN-signaling pathways, as well as oxidative phosphorylation, protein translation, and unfolded protein response during reactivation. Despite distinct subcellular localizations, RSAD2 at the Endoplasmic Reticulum (ER), and CMPK2 in mitochondria, both genes converge on shared immunometabolic pathways, including control of Gasdermin D (GSDMD) associated pyroptosis and ATF-4 associated unfolded protein response (UPR). EBV reactivation induced formation of antiviral ribonucleotide ddhCTP during lytic EBV reactivation which was strictly dependent on RSAD2. Knockdown of RSAD2 and CMPK2 had significant effects on global metabolites consistent with a remodeling of glycolysis, fatty acid biosynthesis and degradation of superoxides. These observations demonstrate that RSAD2-CMPK2 function in a coordinated ER-mitochondria stress-Interferon signaling axis that shapes EBV reactivation and host immune control, including a novel layer of immunometabolic regulation modulating viral latency and reactivation. Authors SummaryUnderstanding how Epstein-Barr virus (EBV) regulates host factors to control infection, latency and reactivation is critical for developing targeted therapies against EBV-associated diseases. This study identifies Interferon Stimulated Genes RSAD2 (Viperin) and CMPK2 as key regulators of EBV reactivation and host interferon responses in B-cells. Despite distinct organelle localizations, both genes converge on a shared immunometabolic pathways, revealing a coordinated ER-mitochondria axis that shapes viral expression and immune signaling. These findings provide new insights into the roles of host antiviral effectors and uncover potential targets for modulating EBV activity in inflammatory and oncogenic contexts.

microbiology↗

bioRxiv2025

Histone Variant H2A.Z Cooperates with EBNA1 to Maintain Epstein-Barr Virus Latent Epigenome

Chromatin structure plays a central role in the regulation of Epstein-Barr Virus (EBV) latency. The histone variant H2A.Z.1 has been implicated in chromatin structures associated with initiation of transcription and DNA replication. Here, we investigate the functional role of H2AZ.1 in the regulation of EBV chromatin, gene expression and copy number during latent infection. We found that H2A.Z.1 is highly enriched with EBNA1 binding sites at oriP and Qp, and to a lesser extent with transcriptionally active CTCF binding sites on the EBV genomes in both Mutu I Burkitt lymphoma (BL) and SNU719 EBV-associated gastric carcinoma (EBVaGC) cell lines. RNA-interference depletion of H2A.Z.1 resulted in the reactivation of viral lytic genes (ZTA and EAD) and increases viral DNA copy numbers in both MutuI and SNU719 cells. H2A.Z depletion also led to a decrease in EBNA1 binding to oriP and Qp, on the viral episome as well as on oriP plasmids independently of other viral genes and genomes. H2A.Z.1 depletion also reduced peaks of H3K27ac and H4K20me3 at regulatory elements in the EBV genome. In the cellular genome, H2A.Z.1 colocalized with only a subset of EBNA1 binding sites and H2A.Z.1 depletion altered transcription of genes associated with myc targets and mTORC1 signaling. Taken together, these findings indicate that H2A.Z.1 cooperates with EBNA1 to regulate chromatin structures important for epigenetic programming of the latent episome. ImportanceCellular factors the restrict latent viral reactivation are of fundamental importance. We have found that the cellular histone variant H2A.Z functions in cooperation with the Epstein-Barr Virus (EBV) latency maintenance protein EBNA1 to establish a stable epigenome and restrict lytic cycle reactivation during latency. We show that H2A.Z co-occupies EBNA1 binding sites on the EBV and host genome, and that depletion of H2A.Z leads to robust reactivation of EBV from latency. H2A.Z is important for the function of EBNA1 at the origin of plasmid (oriP) replication and establishing EBV epigenetic marks. H2A.Z binds with EBNA1 at cellular binding sites and controls the expression of cellular genes in the cMyc and mTORC1 pathways that are also implicated in control of EBV latency.

molecular biology↗

bioRxiv2024

A Novel Human TBCK- Neuronal Cell Model Results in Severe Neurodegeneration and Partial Rescue with Mitochondrial Fission Inhibition

Background and ObjectivesTBCK syndrome is a rare fatal pediatric neurodegenerative disease caused by biallelic loss-of-function mutations in the TBCK gene. Previous studies by our lab and others have implicated mTOR, autophagy, lysosomes, and intracellular mRNA transport, however the exact primary pathologic mechanism is unknown. This gap has prevented the development of targeted therapies. MethodsWe employed a human neural progenitor cell line (NPC), ReNcell VM, which can differentiate into neurons and astrocytes, to understand the role of TBCK in mTORC1 activity and neuronal autophagy and cellular mechanisms of pathology. We used shRNA technology to knockdown TBCK in ReNcells. ResultsThese data showed that loss of TBCK did not inhibit mTORC1 activity in neither NPC nor neurons. Additionally, analysis of eight patient-derived cells and TBCK knock down HeLa cells showed that mTORC1 inhibition is inconsistent across different patients and cell types. We showed that TBCK knockdown in ReNcells affected NPC differentiation to neurons and astrocytes. Specifically, differentiation defects are coupled to cell cycle defects in NPC and increased cell death during differentiation. RNAseq analysis indicated the downregulation of several different neurodevelopmental and differentiation pathways. We observed a higher number of LC3-positive vesicles in the soma and neurites of TBCK knockdown cells. Further, TBCK knockdown altered mitochondrial dynamics and membrane potential in NPC, neurons and astrocytes. We found partial mitochondrial rescue with the mitochondrial fission inhibitor mdivi- 1. DiscussionThis work outlines a new Human Cell Model for TBCK-related neurodegeneration and the essential role of mitochondrial health and partial rescue with mitochondrial fission inhibitor. This data, along with human neurons and astrocytes, illuminate mechanisms of neurodegeneration and provide a possible novel therapeutic avenue for affected patients.

neuroscience↗

bioRxiv2021

Chromatin and transcriptomic profiling uncover dysregulation of the Tip60 HAT/HDAC2 epigenomic landscape in the neurodegenerative brain

Disruption of histone acetylation mediated gene control is a critical step in Alzheimers Disease (AD), yet chromatin analysis of antagonistic histone acetyltransferases (HATs) and histone deacetylases (HDACs) causing these alterations remains uncharacterized. We report the first Tip60 HAT versus HDAC2 chromatin and transcriptional profiling study in Drosophila brains that model early human AD. We find Tip60 and HDAC2 predominantly recruited to identical neuronal genes. Moreover, AD brains exhibit robust genome-wide early alterations that include enhanced HDAC2 and reduced Tip60 binding and transcriptional dysregulation. Orthologous human genes to co-Tip60/HDAC2 Drosophila neural targets exhibit conserved disruption patterns in AD patient hippocampi. Notably, we discovered distinct transcription factor (TF) binding sites within Tip60/HDAC2 co-peaks in neuronal genes, implicating them in co-enzyme recruitment. Increased Tip60 protects against transcriptional dysregulation and enhanced HDAC2 enrichment genome-wide. We advocate Tip60 HAT/HDAC2 mediated epigenetic neuronal gene disruption as a genome-wide initial causal event in AD.

genomics↗

bioRxiv2020

Transcriptome analysis uncovers distinct modes of epigenetic gene changes in early versus late stages of amyloid-β induced Alzheimer's disease pathology

Alzheimers disease (AD) is an age-related neurodegenerative disorder hallmarked by amyloid-{beta} (A{beta}) plaque accumulation, neuronal cell death, and cognitive deficits that worsen during disease progression. Histone acetylation dysregulation, caused by an imbalance between reduced histone acetyltransferases (HAT) Tip60 and increased histone deacetylase 2 (HDAC2) levels, can directly contribute to AD pathology. However, whether such AD-associated neuroepigenetic alterations occur in response to A{beta} peptide production and can be protected against by increasing Tip60 levels over the course of neurodegenerative progression remains unknown. Here we profile Tip60 HAT/HDAC2 dynamics and transcriptome-wide changes across early and late stage AD pathology in the Drosophila brain produced solely by human amyloid-{beta}42. We show that early A{beta}42 induction leads to disruption of Tip60 HAT/HDAC2 balance during early neurodegenerative stages preceding A{beta} plaque accumulation that persists into late AD stages. Correlative transcriptome-wide studies reveal alterations in biological processes we classified as transient (early-stage only), late-onset (late-stage only), and constant (both). Increasing Tip60 HAT levels in the A{beta}42 fly brain protects against AD functional pathologies that include A{beta} plaque accumulation, neural cell death, cognitive deficits, and shorter life-span. Strikingly, Tip60 protects against A{beta}42-induced transcriptomic alterations via distinct mechanisms during early and late stages of neurodegeneration. Our findings reveal distinct modes of neuroepigenetic gene changes and Tip60 neuroprotection in early versus late stages in AD that can serve as early biomarkers for AD, and support the therapeutic potential of Tip60 over the course of AD progression.

neuroscience↗