Regulation of T Cell Responses by Chaperone-Mediated Autophagy

Abstract T cell activation requires a tight regulation of positive and negative modulators of signaling pathways downstream of the T cell receptor (TCR). Degradation of specific proteins following TCR engagement is an essential regulatory mechanism that ensures efficient T cell responses. Chaperone-mediated autophagy (CMA) is an inducible form of autophagy that selectively degrades soluble cytosolic proteins that present a pentapetide targeting motif. The ability of CMA to selectively degrade proteins makes this type of autophagy a candidate to contribute to the regulation of the levels of specific signaling intermediates in response to different stimuli. We have recently shown that CMA is activated in CD4+ T cells in response to TCR engagement to regulate signaling pathways downstream of the TCR by selectively targeting inhibitors of TCR signaling for degradation in the lysosomes. In this proposal we intend to elucidate the molecular mechanisms that explain how this specific form of autophagy modulates CD4+ T cell function and characterize how CMA regulates adaptive immune responses in vivo. Our overall goal is to define CMA as a novel regulatory mechanism of T cell activation and to determine the possibility of targeting CMA to modulate T cell responses.