Vemula, P. | Search bioRxiv

bioRxiv2023

Phase Separation of a Novel form of Euchromatic Histone Methyltransferase1 (EHMT1N/C) into cytoplasmic RNA viral Inclusion bodies facilitates their coalescence, thereby enhancing viral replication

Protein lysine methyltransferases (PKMTs) methylate histone and non-histone proteins to regulate biological outcomes such as development and disease including viral infection. While PKMTs have been extensively studied for modulating the antiviral responses via host gene regulation, their role in methylation of proteins encoded by viruses and its impact on host-pathogen interactions remain poorly understood. In this study, we discovered a distinct nucleo-cytoplasmic form of Euchromatic Histone Methyltransferase1(EHMT1N/C), a PKMT, that phase separates into viral inclusion bodies (IBs) upon cytoplasmic RNA-virus infection (Sendai Virus). EHMT1N/C interacts with cytoplasmic EHMT2 and methylates SeV-Nucleoprotein upon infection. Elevated nucleoprotein methylation during infection correlated with coalescence of small IBs into large mature platforms for efficient replication. Inhibition of EHMT activity by pharmacological inhibitors or genetic depletion of EHMT1N/C reduced the size of IBs with a concomitant reduction in replication. Since IB formation is conserved among all cytoplasmic RNA-viruses, our study will have strong implications in understanding the mechanisms regulating IB formation, discerning RNA viral pathogenesis and designing therapeutic strategies.

cell biology↗

bioRxiv2022

Evaluating the efficacy of commercially available antisense oligonucleotides to reduce mouse and human tau in vivo

Tauopathies, including Alzheimers disease (AD), are neurodegenerative diseases characterized by the accumulation of tau protein encoded by the MAPT (Microtubule Associated Protein Tau) gene. Various strategies targeting mechanisms to reduce tau pathology have been proposed and several tau-directed therapies are being investigated in clinical trials. Our lab previously developed a novel strategy to lower tau protein levels using antisense oligonucleotides (ASOs), showing that human tau (hTau) reduction in aged PS19 tauopathy mice reversed phosphorylated tau pathology, spared neurons, and prolonged survival. Currently, the tau-lowering ASO is being evaluated in the clinical trials with successful phase 1b results. Similarly, preclinical and clinical studies have demonstrated the use of other ASOs as effective therapeutic strategies. Acquiring ASOs for research purposes may be limited by partnerships with pharmaceutical companies. However, ASOs can be obtained through commercial vendors. The current study evaluates the efficacy of mouse and human tau-targeting ASOs obtained from a commercial vendor in various mouse models. We show that mice treated with purchased ASOs distribute among various brain cell types including neurons, microglia, and astrocytes. Mice treated with tau lowering ASOs show decreased mouse or human tau mRNA and protein levels. In addition, human tau lowering ASO-treated PS19 mice showed decreased phosphorylated tau (AT8) and gliosis relative to saline-treated PS19 mice. The results obtained in PS19 mice are consistent with data obtained from our previous study using a non-commercial tau-lowering ASO. Overall, the present study demonstrates the efficacy of commercially-available tau targeting ASOs in vivo to support their broad use by researchers.

neuroscience↗