RAGE, Diabetes and Myocardial Infarction

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DESCRIPTION (provided by applicant): Earlier studies from our laboratory have uncovered key roles for RAGE in myocardial infarction, as global deletion RAGE resulted in decreased myocardial necrosis, increased functional recovery and preservation of ATP compared to wild-type mice after ischemia/reperfusion (I/R) in the isolated perfused heart or after occlusion/reperfusion of the left anterior descending (LAD) coronary artery. RAGE is expressed broadly in multiple cell types that impact on the heart's response to I/R injury, such as monocytes/macrophages, endothelial cells and cardiomyocytes. RAGE contributes to oxidative stress consequent to I/R and influences mitochondrial dysfunction that accompanies injury to the heart. In this application, we will probe the "cross- talk" between inflammatory, vascular and cardiomyocyte stresses evoked by I/R in the heart using murine models, both in the absence and presence of diabetes. Our overall hypothesis is that RAGE signaling in monocytes/macrophages, endothelial cells and cardiomyocytes is, overall, highly detrimental to the injured heart. We predict that in I/R, monocytes/macrophages produce damaging mediators that disrupt effective healing and that RAGE-dependent endothelial stress, particularly in diabetes, thwarts effective remodeling. Lastly, we predict that cardiomyocyte RAGE, highly upregulated in the murine heart after I/R, signals devastating metabolic consequences in the healing myocardium, which trigger mitochondrial dysfunction, in part through GSK-3b and apoptotic events. Two novel findings in our laboratory suggest roles for mDia-1, a member of the formin homology domain protein family and an effector of RhoGTPases, and the ROCK 1 signaling pathway in RAGE-mediated cardiovascular stress. In this application, we will probe the role of RAGE in the full context of RAGE-dependent mDia-1 and/or ROCK signaling in the heart. Only by a full understanding of potentially adaptive roles for cell-specific RAGE signaling in myocardial infarction, and the proximate signaling cascades stimulated by this receptor in I/R, will the optimal design of RAGE antagonism be achieved.