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Tiam1/Rac1 complex controls Il17a transcription and autoimmunity.

Nature communications (2016-10-12)
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
ABSTRACT

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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Anti-β-Actin−Peroxidase antibody, Mouse monoclonal, clone AC-15, purified from hybridoma cell culture
Sigma-Aldrich
Duolink® In Situ Red Starter Kit Mouse/Rabbit
Sigma-Aldrich
Anti-Tiam1 Rabbit pAb, liquid, Calbiochem®