Mapping REV-ERBα’s Protein-Protein Interactions to Understand TH17 Cell Regulation and Inflammation 2258028

Abstract Introduction TH17 cells are a subset of CD4+ T cells that mediate autoimmune and chronic inflammatory pathology. Our lab has previously demonstrated that REV-ERBα, a member of the nuclear receptor superfamily of ligand-regulated transcription factors, represses TH17 development in vitro and protects against relevant models of disease in vivo. While REV-ERBα’s target genes and binding sites have been identified across multiple tissues, little is known about the transcriptional machinery that drives its function. Methods We coupled MiniTurboID proximity labeling with label-free proteomics to 1) identify key proteins that facilitate REV-ERBα-mediated gene repression in primary, murine TH17 cells and 2) further understand how ligands modulate this process. Furthermore, we have conducted a pooled in vivo RNAi screen to examine our proteomics hits in a physiologically relevant context. Specifically, we utilized Il17a reporter REV-ERB deficient and sufficient T-cells along with shRNAs targeting our identified REV-ERBα interactors in a mouse model of colitis. Results Comparison of the REV-ERBα interactome induced by the presence and absence of endogenous ligand binding reveals potential canonical and non-canonical mechanisms of repression. Additionally, comparison of the shRNAs enriched in colon cells expressing high versus low levels of IL-17A have elucidated which REV-ERBα interactors regulate TH17 pathogenicity in a REV-ERB-dependent manner. Conclusion Ultimately, these efforts aim to bolster our understanding of the REV-ERBs, nuclear receptor biology, and TH17 pathogenesis–all of which may inform the development of focused therapeutics for treatment of autoimmune and chronic inflammatory diseases. Funding Source NA Topic Categories Basic Autoimmunity (BA)