Signaling Pathways and Epigenetic Regulations in the Control of RORγt Expression in T Helper 17 Cells

T helper 17 (Th17) cells constitute a unique T-cell lineage that plays a crucial role in inflammatory diseases. A decade ago, retinoic acid receptor-related orphan receptor-gamma t (ROR gamma t) was identified as the specific transcription factor required for Th17-cell lineage commitment. However, the underlying mechanisms involved in the regulation of the ROR gamma t expression remain largely unclear and therefore preclude the accurate identification and manipulation of Th17 cells. In this review, we summarize the recent advances to obtain an understanding of how ROR gamma t expression is controlled at the molecular level, highlighting the importance of signal transduction pathways and epigenetic regulations in the control of ROR gamma t expression in Th17 cells.