Fig. 2: Role of Rho GTPases in the adaptive immune system.

Abnormal T cells activation, accumulation, differentiation of different T cells subsets and inappropriate apoptosis are linked to IBD immunopathogenesis. Rho GTPases are involved in T cells basic functions. Migration of T cell initiates with enhanced adhension mediated by Rac and RhoA, the former also participates in lymphocyte homing. Cdc42, Rac and RhoA regulate T cell movement with different mechanisms. Effective T cell activation requires stable conjunction between T cell and APC and the signaling transduction. RhoA and Rac contribute to both the process while Cdc42 enhances the former process and inhibits the latter. RhoH and RhoG are also involved in signaling transduction, mainly exerting a positive and negative function, respectively. Rho GTPases also help lymphocytes differentiate into diverse effector or regulatory T cell subsets to participate in inflammatory and anti-inflammatory processes. Cdc42, Rac and RhoA are involved in the Fas/FasL induced apoptosis of T cell, both in the induction and late stage. WASp Wiskott-Aldrich syndrome protein, Arp2/3 actin-related protein 2/3, IS immunological synapse, ERM protein ezrin-radixin-moesin protein, JNK c-jun N-terminal kinase, AP-1 activate protein-1, NFAT nuclear factor of activated T cells, NF-κB nuclear factor of kappa B, IL-12 interluekin-12.