| WASH is an ARP2/3-activator of the WASP superfamily that functions during endosomal trafficking processes in collaboration with the retromer and sorting nexins, but its in vivo function has not been examined. To elucidate the physiological role of WASH in T cells we generated a WASH conditional knockout (WASHout) mouse model. Using CD4 Cre deletion, we find thymocyte development and naïve T cell activation are unaltered in the absence of WASH. Surprisingly, despite normal TCR signaling and IL-2 production, WASHout T cells demonstrate significantly reduced proliferative potential and fail to effectively induce experimental autoimmune encephalomyelitis. Interestingly, following activation, WASHout T cells fail to maintain surface levels of TCR, CD28, and LFA-1. Moreover, levels of the glucose transporter, GLUT1, are also reduced compared to WT T cells. We further demonstrate that the loss of surface expression in WASHout cells results from aberrant accumulation within the collapsed endosomal compartment, ultimately leading to degradation within the lysosome. Subsequently, activated WASHout T cells experience reduced glucose uptake and metabolic output. Thus, it appears that WASH is a newly recognized regulator of TCR, CD28, LFA-1 and GLUT1 endosome-to-membrane recycling. Aberrant trafficking of these key T cell proteins may potentially lead to attenuated proliferation and effector function. |
