Tiam1/Rac1 complex controls Il17a transcription and autoimmunity

Ahmed T. Kurdi, Ribal Bassil, Marta Olah, Chuan Wu, Sheng Xiao, Mariko Taga, Michael Frangieh, Thomas Buttrick, William Orent, Elizabeth M. Bradshaw, Samia J. Khoury, Wassim Elyaman

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


RORγt is a master transcription factor of Th17 cells and considered as a promising drug target for the treatment of autoimmune diseases. Here, we show the guanine nucleotide exchange factor, Tiam1, and its cognate Rho-family G protein, Rac1, regulate interleukin (IL)17A transcription and autoimmunity. Whereas Tiam1 genetic deficiency weakens IL-17A expression partially and inhibits the development of experimental autoimmune encephalomyelitis (EAE), deletion of Rac1 in T cells exhibits more robust effects on Th17 cells and EAE. We demonstrate Tiam1 and Rac1 form a complex with RORγt in the nuclear compartment of Th17 cells, and together bind and activate the Il17 promoter. The clinical relevance of these findings is emphasized by pharmacological targeting of Rac1 that suppresses both murine and human Th17 cells as well as EAE. Thus, our findings highlight a regulatory pathway of Tiam1/Rac1 in Th17 cells and suggest that it may be a therapeutic target in multiple sclerosis.

Original languageEnglish
Article number13048
JournalNature Communications
StatePublished - Oct 11 2016
Externally publishedYes


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