Inhibition of T Cell Activation by Cyclic Adenosine 5′-Monophosphate Requires Lipid Raft Targeting of Protein Kinase A Type I by the A-Kinase Anchoring Protein Ezrin

摘要: cAMP negatively regulates T cell immune responses by activation of type I protein kinase A (PKA), which in turn phosphorylates and activates C-terminal Src (Csk) lipid rafts. Using yeast two-hybrid screening, far-Western blot, immunoprecipitation immunofluorescense analyses, small interfering RNA-mediated knockdown, we identified Ezrin as the A-kinase anchoring that targets PKA to Furthermore, brings proximity its downstream substrate Csk rafts forming a multiprotein complex consisting PKA/Ezrin/Ezrin-binding 50, Csk, Csk-binding protein/phosphoprotein associated with glycosphingolipid-enriched microdomains. The is initially present immunological synapses when cells contact APCs subsequently exits distal pole. Introduction an disruptor peptide (Ht31) into competes binding thereby releases cAMP/PKA I-mediated inhibition proliferation. Finally, knockdown abrogates regulation IL-2. We propose essential assembly cAMP-mediated regulatory pathway modulates responses.