Biology subjects

Tripathi, S. K.

Publications and source records attributed to Tripathi, S. K..

6 recordsLinked to original sources

bioRxiv2026

CD19 CAR Engineered T Regulatory Cells Promote Durable Immune Tolerance in Experimental Systemic Lupus Erythematosus

While the immune reset induced by CD19 CAR T therapies has shown striking promise in systemic lupus erythematosus (SLE), the nature and duration of benefit mediated by B cell depletion remains unclear. Loss of tolerance in SLE is driven by extrafollicular and germinal center interactions between dendritic cells and self-reactive T and B cells. We hypothesized that CD19 CAR-engineered regulatory T cells (CAR19 EngTreg), capable of suppressing multiple autoimmune effector cell types, might promote long-term tolerance without producing high-levels of inflammatory mediators. To generate CAR19 EngTreg, we combined CD19 CAR delivery with homology directed repair at the FOXP3 locus to drive constitutive, stable FOXP3 expression in CD4 T cells. CAR19 EngTreg expressed canonical Treg markers; exhibited minimal inflammatory cytokine production; and blocked human B cell differentiation into antibody secreting plasma cells. In humanized mouse models, transfer of CAR19 EngTreg led to a reduction in B cell numbers with low inflammatory cytokine production relative to CD19 CAR Teff, and reduced tissue inflammation. In a short-term, in vivo imiquimod-induced inflammatory model, murine CAR19 EngTreg reduced skin pathology, spleen size, and inflammatory cytokines. Finally, in two distinct mouse models of lupus, CAR19 EngTreg persisted for >4 months leading to reduced autoimmune T and B effector populations, sustained reduction in multiple autoantibodies and improved renal function and histopathology. Thus, CAR19 EngTreg may offer a promising and durable therapeutic avenue for B cell-mediated autoimmune disorders capable of long-term regulation of both autoreactive B and T cells.

immunology↗

bioRxiv2023

p53 translational isoform {triangleup}40p53 orchestrates cellular SGSH levels via microRNA-4671-5p to modulate cell cycle

{Delta}40p53, the only translational isoform of p53, modulates the full-length p53 (FLp53) activity and independently regulates targets such as the miR-186-5p-YY1 axis. To identify additional miRNAs regulated by {Delta}40p53, we performed small RNA sequencing. We found that overexpression of {Delta}40p53, but not FLp53, significantly downregulated miR-4671-5p. Expression of both isoforms at varying ratios revealed that miR-4671-5p may be modulated by FLp53 in a {Delta}40p53-dependent manner. In silico analysis identified SGSH (N-sulfoglucosamine sulfohydrolase) as a potential miR-4671-5p target. SGSH expression showed inverse correlation with miR-4671-5p in cancer datasets and prognostic significance. SGSH mRNA and protein levels were reduced upon miR-4671-5p overexpression or si{Delta}40p53 treatment, confirming regulatory linkage. Functionally, miR-4671-5p overexpression induced intra-S-phase cell cycle arrest, implicating SGSH in cell cycle regulation. These results reveal a novel {Delta}40p53-miR-4671-5p-SGSH axis that impacts cell cycle progression and may contribute to cancer outcomes. Our findings highlight the distinct regulatory role of {Delta}40p53, independent of FLp53, in maintaining cellular and metabolic homeostasis via miRNA-mediated mechanisms.

molecular biology↗

bioRxiv2022

Discovery, Synthesis, and Optimization of 1,2,4-Triazolyl Pyridines Targeting Mycobacterium tuberculosis

Tuberculosis (TB) results in 1.5 million deaths every year. The rise in multi-drug resistant TB underscores the urgent need to develop new antibacterials, particularly those with new chemical entities and/or novel mechanisms of action that can be used in combination therapy with existing drugs to prevent the rapid emergence of resistance. Herein, we report the discovery and synthesis of a new series of compounds containing a 3-thio-1,2,4-triazole moiety that show inhibition of Mycobacterium tuberculosis (Mtb) growth and survival. Structure-activity relationship studies led us to identify potent analogs displaying nanomolar inhibitor activity, specifically against Mtb. These potent analogs exhibit a promising ADME/pharmacokinetic profile and no cytotoxicity in mammalian cells at over 100 times the effective dose in Mtb. Our preliminary investigations into the mechanism of action suggest this series is not engaging promiscuous targets and, thereby, could be acting on a novel target. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/516356v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@1fd7a78org.highwire.dtl.DTLVardef@738c7dorg.highwire.dtl.DTLVardef@c7957org.highwire.dtl.DTLVardef@f26ae3_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2021

6',6'-Difluoro-aristeromycin is a potent inhibitor of MERS-coronavirus replication

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has highlighted the lack of treatments to combat infections with human or (potentially) zoonotic CoVs. Thus, it is critical to develop and evaluate antiviral compounds that either directly target CoV functions or modulate host functions involved in viral replication. Here, we demonstrate that low-micromolar concentrations of 6',6'-difluoro-aristeromycin (DFA), an adenosine nucleoside analogue, strongly inhibit the replication of Middle East respiratory syndrome coronavirus (MERS-CoV) in a cell-based infection assay. DFA was designed to target S-adenosylhomocysteine (SAH) hydrolase and, consequently, may affect intracellular levels of the methyl donor S-adenosylmethionine, which is used by two CoV methyltransferases involved in the capping of the 5 end of the viral mRNAs. Passaging of wild-type MERS-CoV in the presence of DFA selected a virus population with a [~]100-fold decreased DFA sensitivity, which carried various amino acid substitutions in viral nonstructural proteins (nsps). Specifically, mutations were present in the RNA polymerase subunit (nsp12) and in nsp13, the helicase subunit containing a nucleoside triphosphate hydrolase activity that has been implicated in CoV capping. We hypothesize that DFA directly or indirectly affects viral cap methylation, either by inhibiting the viral enzymes involved or by binding to SAH hydrolase. We also evaluated the antiviral activity of DFA against other betacoronaviruses, but found it to have limited impact on their replication, while being quite cytotoxic to the Calu-3 cells used for this comparison. Nevertheless, our results justify the further characterization of DFA derivatives as an inhibitor of MERS-CoV replication. ImportanceCurrently, there is a lack of antiviral drugs with proven efficacy against human CoV infections including the MERS-CoV that is endemic in the Middle East, the pandemic SARS-CoV-2 and potential future zoonotic CoV. This highlights the importance to investigate new drug targets and identify compounds that can be used to inhibit CoV replication. In this study, we characterize the inhibitory effect of DFA on MERS-CoV replication by phenotypic studies, time-of-addition studies, and the generation and genotyping of a DFA-resistant virus population. Our results revealed that DFA needs further improvement to reduce its cytotoxic side-effects and potentially enhance its broad-spectrum activity. Despite this observation, we think that DFA can be used to understand the function and metabolic interactions of the CoV RNA-synthesizing machinery, or as a starting point for the design of new compounds of the same class.

microbiology↗

bioRxiv2021

Mapping Interactome Networks of FOSL1 and FOSL2 in Human Th17 Cells

Dysregulated function of Th17 cells has implications in immunodeficiencies and autoimmune disorders. Th17 cell-differentiation is orchestrated by a complex network of transcription factors, including several members of the activator protein (AP-1) family. Among these, FOSL1 and FOSL2 influence the effector responses of Th17 cells. However, the molecular mechanisms underlying these functions are unclear, owing to the poorly characterized protein interaction networks of these factors. Here, we establish the first interactomes of FOSL1 and FOSL2 in human Th17 cells, using affinity purification-mass spectrometry analysis. In addition to the known JUN proteins, we identified several novel binding partners of FOSL1 and FOSL2. Gene ontology analysis found a major fraction of these interactors to be associated with RNA binding activity, which suggests new mechanistic links. Intriguingly, 29 proteins were found to share interactions with FOSL1 and FOSL2, and these included key regulators of Th17-fate. We further validated the binding partners identified in this study by using parallel reaction monitoring targeted mass-spectrometry and other methods. Our study provides key insights into the interaction-based signaling mechanisms of FOSL factors that potentially govern Th17 cell-differentiation and associated pathologies.

immunology↗

bioRxiv2021

The AP-1 factors FOSL1 and FOSL2 co-regulate human Th17 responses

Th17 cells protect mucosal barriers, but their aberrant activity can cause autoimmunity. Molecular networks dictating human Th17 function are largely unexplored, and this hinders disease-studies. Here, we investigated the roles of the AP-1 factors, FOSL1 and FOSL2, in inducing human Th17 responses. Transient knockdown and over-expression strategies found the two proteins to inhibit Th17-cell identity, while revealing a distinct cooperativity between their functions. Strikingly, FOSL1 plays different roles in human and mouse and FOSL-mediated Th17 regulation is opposed by the AP-1 factor, BATF. Genome-wide occupancy analysis demonstrated the co-localization of FOSL1, FOSL2 and BATF in the vicinity of key Th17 genes. The functional interplay among these factors is possibly governed by sharing interactions with a common set of lineage-associated proteins. We further discovered that the genomic binding sites of these factors harbour a large number of disease-linked SNPs, many of which alter the ability of a given factor to bind DNA. Our findings thus provide crucial insights into the transcriptional regulation of human Th17 function and associated pathologies. ONE SENTENCE SUMMARYFOSL1- and FOSL2-mediated transcription during early human Th17 differentiation

immunology↗