Regulation of Pathogenic T Helper 17 Cell Differentiation by Steroid Receptor Coactivator-3

Abstract

Summary: T helper 17 (Th17) cell development is programmed by the orphan nuclear receptor RORγt, but the underlying mechanism is not well understood. Nuclear receptor-mediated transcriptional activation depends on coactivators. Here, we show that steroid receptor coactivator-3 (SRC-3) critically regulates Th17 cell differentiation. Reduced incidence of experimental autoimmune encephalitis (EAE) associated with decreased Th17 cell generation in vivo was observed in mice with SRC-3 deletion specifically in T cells. In vitro, SRC-3 deficiency did not affect TGF-β/IL-6-induced Th17 cell generation but severely impaired pathogenic Th17 differentiation induced by IL-1/IL-6/IL-23. Microarray analysis revealed that SRC-3 not only regulates IL-17A but also IL-1R1 expression. SRC-3 bound to Il17a and Il1r1 loci in a RORγt-dependent manner and was required for recruitment of the p300 acetyltransferase. Thus, SRC-3 is critical for RORγt-dependent gene expression in Th17 cell-driven autoimmune diseases. : The unique transcriptional programs in IL-1-induced inflammatory Th17 cells have remained unclear. Tanaka et al. demonstrate that SRC-3 in CD4+ T helper cells functions as a specific coactivator of RORγt, a master transcription factor of Th17 cells, by regulating IL-1-IL1R1 signaling. Keywords: steroid receptor coactivator-3, pathogenic Th17, RORγt, EAE, IL1R1, IL17A, p300