Mechanisms of Atherogenesis in Insulin Resistance

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DESCRIPTION (provided by applicant): The epidemic of obesity is causing a sharp rise in the incidence of insulin resistance and its major complication, atherosclerotic cardiovascular disease (CVD). Thus, there is great interest in understanding the role of insulin resistance in both hepatic dyslipidemia, which triggers and maintains atherosclerosis, and in atherogenic events occurring in the plaque cells themselves. The proposed PPG will bring together experts in these different areas working towards a common goal and with a proven record of success over the last 5 years of funding. The overall theme of the PPG is to elucidate novel signal transduction pathways in the liver and in lesional macrophages (Mfs) and endothelial cells (ECs) that contribute to the dyslipidemia and accelerated atherosclerotic lesion progression in insulin-resistant states. In Project 1, Dr. Tabas will focus on the enzyme CaMKII, which has a critical role in (a) both basal and insulin resistance-exacerbated apoptosis of endoplasmic reticulum (ER)-stressed Mfs, which leads to plaque necrosis; and (b) in hepatic derived metabolic disturbances, including dyslipidemia and alterations in FoxO signaling, in obesity and insulin resistance. In Project 2, Dr. Tall will investigate the cellular-molecular mechanisms of hepatic-derived dyslipidemia in insulin resistance, with, emphasis on a novel mTORC1-Sortilin1 pathway that is relevant to recent human genetic studies and, as recent data shows, linked to ER stress and CaMKII. In Project 3, Dr. Accili will focus on vascular ECs as a key site of interaction between insulin resistance and hyperglycemia in atherosclerosis. The emphasis will be on how insulin resistance and hyperglycemia signal through the FoxO proteins to promote atherogenic processes in ECs. Each project will be supported by the Lesion Analysis/Biostatistics Core, in which Dr. Welch's team will provide assistance and expertise in atherosclerosis assays and in biomathematics. The common sub-themes among the projects include: (a) molecules and pathways involved in pro-atherogenic lesional cell dysfunction (Mfs, ECs), including FoxO's, ER stress, CaMKII, mTORC1 (all 3 projects); (b) pathways involved insulin resistance-induced dyslipidemia, including FoxO's, ER stress, mTORC1, Sortilin1, and CaMKII (Projects 1 and 2 in collaboration with Dr. Accili); and (c) mouse models of atherosclerotic lesion development and advanced plaque progression/plaque necrosis (all 3 projects and Core A). The synergistic and highly interactive nature of these projects and the complementary expertise in atherosclerosis and diabetes will enable a unique opportunity to address the emerging epidemic of insulin resistance-associated heart disease.