Abstract 20279: Signalosomes Orchestrate Ouabain-Induced Intracellular Inotropic Signaling

Introduction: Receptor-mediated, intracellular signaling leading to cardioprotection and inotropy is orchestrated by signalosome. The caveolar vesicles bud off the plasma membrane, move to mitochondria, and use a terminal kinase to phosphorylate an outer membrane protein. This activates an inner membrane PKCe that opens the mitochondrial ATP-sensitive K+ channel (mitoKATP), which is required for positive inotropy induced by ouabain, Ca2+, and dobutamine. Hypothesis: We propose that positive inotropic signaling is mediated by a signalosome mechanism, whereby activation of its receptor, Na,K-ATPase, instigates the formation of a caveolar signaling complex that opens mitoKATP. Methods: We isolate signalosomes from Langendorff perfused rat hearts treated with ouabain, use light scattering to assay their ability to open mitoKATP in untreated isolated mitochondria, and investigate their molecular composition, assembly, and regulation using immunocytochemistry, quantitative proteomics, and bioinformatic approach...