Biology subjects

Pandit, M.

Publications and source records attributed to Pandit, M..

4 recordsLinked to original sources

bioRxiv2026

EBV reprograms autoreactive B cells as antigen presenting cells in multiple sclerosis

Summary paragraphMultiple sclerosis (MS) is a chronic autoimmune disease targeting the central nervous system (CNS). MS develops almost exclusively in individuals previously infected with Epstein-Barr virus (EBV)1, yet the mechanisms linking EBV infection to MS pathogenesis remain incompletely defined. Here we characterized EBV-infected B cells in MS and demonstrated that EBV directly infects autoreactive anti-CNS antigen B cells and reprograms them into pro-inflammatory antigen-presenting cells (APCs). EBV B cells in MS were enriched within the CD27CD21low memory B-cell subset and exhibited upregulated B cell activation and APC transcriptional programs. Recombinant antibodies derived from MS blood and cerebrospinal fluid (CSF) EBV B cells bound brain tissue, and several cross-bound both MS-associated autoantigens and Epstein-Barr virus nuclear antigen-1 (EBNA1). In vitro, EBV B cells functioned as APCs that stimulated T peripheral helper cells, with associated activation of EBV- anti-CNS antigen B cells. Collectively, these findings support a mechanistic framework in which EBV infects and transcriptionally reprograms autoreactive anti-CNS antigen B cells into APCs that drive pathogenic anti-CNS antigen T cell and EBV- B cell responses in MS.

immunology↗

bioRxiv2024

DKC1-mediated pseudouridylation of rRNA targets hnRNP A1 to sustain IRES-dependent translation and ATF4-driven metabolic adaptation

The pseudouridine synthase DKC1 regulates internal ribosome entry site (IRES)-dependent translation and is upregulated in cancers by the MYC family of oncogenic transcription factors. We investigated the functional significance of DKC1 in MYCN-amplified neuroblastoma and its underlying mechanisms. A key function of DKC1 is to promote an ATF4-mediated gene expression program for amino acid metabolism and stress adaptation. We identified hnRNP A1, an IRES trans-acting factor, as a critical downstream mediator of DKC1 in sustaining ATF4 expression and IRES-dependent translation. We found that DKC1-mediated pseudouridylation at two specific 28S rRNA sites is essential for maintaining hnRNP A1 protein expression. Moreover, hnRNP A1 interacts with and stabilizes ATF4 mRNA, significantly increasing the protein expression of the ATF4 V1 variant, which contains an IRES element in its mRNA. Additionally, we found that cellular stress induces hnRNP A1, which is required for ATF4 induction under such conditions. Collectively, our study reveals a MYC-activated DKC1-hnRNP A1 axis that drives ATF4-mediated metabolic adaptation, supporting cancer cell survival under metabolic stress during cancer development.

cancer biology↗

bioRxiv2023

Anti-cancer drug Tamoxifen interferes with Mycobacterium tuberculosis PhoPR mediated signaling and inhibits mycobacterial growth

Two-component signaling (TCS) systems empower all bacteria, including intracellular pathogens like Mycobacterium tuberculosis (M. tb) to regulate key pathways governing growth, physiology and virulence. Amongst all M. tb TCS systems, PhoPR and DevRS have been studied extensively for their roles in regulating persistence and virulence. Here, we report that besides its cognate response regulator PhoP, the PhoR sensor kinase displays several non-cognate interactions that augment its role in pathogenesis. We demonstrate that PhoR phosphorylates the DevR response regulator and furthermore, is itself subjected to O-phosphorylation by PknK, a Ser/Thr protein kinase (STPK), connecting TCS pathways with "eukaryotic-like" STPK driven phosphosignaling. This intersection of non-canonical regulatory pathways and the coregulation of PhoP and DevR regulons make M. tb PhoR a potentially attractive drug target. We rationalized that disruption of PhoPR signaling cascade and the resulting dysregulation may result in decreased virulence of M. tb. We tested this hypothesis by performing a high-throughput screen for compounds that inhibit autophosphorylation of PhoR sensor kinase. Screening of pharmacologically active, small molecule libraries yielded 11 potential inhibitors, of which one compound, Tamoxifen was able to attenuate PhoR autophosphorylation at micromolar concentrations in vitro and in vivo. Tamoxifen not only inhibited growth of Mycobacterium bovis BCG in culture but also interrupted PhoPR-mediated downstream signaling. Quantitative expression analysis revealed suppression of target gene, aprA under acidic conditions. Our findings highlight TCS sensor kinases as promising drug targets and underscore the applicability of clinically relevant anti-cancer drug tamoxifen as a repurposed anti-TB drug.

biochemistry↗

bioRxiv2023

Early life pain alters the response to an immune challenge in adult male and female rats

Infants born prematurely are more likely to be admitted to the Neonatal Intensive Care Unit (NICU) where they experience upwards of 10-18 painful procedures each day, often with no anesthesia or analgesia. Pre-clinical studies have shown that early exposure to pain disrupts CNS development in multiple ways that persist into adulthood, with similar findings observed clinically. The present study explores the effects of neonatal injury on the response to an immune challenge in adulthood. Male and female rats were exposed to a short-term inflammatory insult induced by intraplantar administration of 1% carrageenan (CGN) on the day of birth (P0). In adulthood (P60-P90), rats were implanted with Thermicron iButtons to monitor core body temperature; 14 days later, lipopolysaccharide (LPS) was administered to elicit an immune response. Rats were sacrificed after 24 hours or at their peak fever point and brain tissue collected for immunohistochemical analysis. LPS administration resulted in a significantly greater febrile response in males and females exposed to early life pain compared to controls. Immunohistological analysis revealed sex and treatment differences in Fos labeling in several brain regions, including the PVN. No sex or treatment differences were observed for VGat, VGlut2, or EP3R expression in the MnPO; however, all three increased significantly following LPS administration. Together, these studies are consistent with clinical studies reporting children experiencing unresolved pain during the perinatal period show an increased severity of sickness behavior and altered immune signaling following exposure to a pathogen and will provide a foundation for future studies examining the biological underpinnings.

neuroscience↗