SummaryT helper 17 (Th17) cells regulate mucosal barrier defenses, but also promote multiple autoinflammatory diseases. Although many molecular determinants of Th17 cell differentiation have been described, the transcriptional programs that sustain Th17 cells in vivo remain obscure. The transcription factor RORγt is critical for Th17 cell differentiation, but a distinct role of the closely-related RORα, which is co-expressed in Th17 cells, is not known. Here we demonstrate that, although dispensable for Th17 cell differentiation, RORα governs optimal Th17 responses in peripheral tissues. Thus, the absence of RORα in T cells led to significant reductions in both RORγt expression and effector function amongst Th17 cells, due to need for cooperative RORα and RORγt binding to a newly-identified Rorc enhancer element that is essential for Th17 lineage maintenance in vivo. Altogether, these data point to a non-redundant role of RORα in Th17 lineage maintenance via reinforcement of the RORγt transcriptional program.
E16 Transcriptional regulation and role of the commensal microbiota in Th17 cell differentiation
