AMP-activated protein kinase in the ischemic heart

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DESCRIPTION (provided by applicant): The overall aim of our research is to define the cellular and molecular mechanisms determining the response of the heart to myocardial ischemia, with the long-term goal to develop novel therapeutic approaches for patients with coronary artery disease. The AMP-activated protein kinase (AMPK) is emerging as an important intracellular signaling pathway with important relevance to human disease, including ischemic heart disease, diabetes, and cancer. AMPK modulates major metabolic pathways, gene transcription, and mitochondrial biogenesis. Our laboratory has elucidated the importance of AMPK in the heart, where it protects against myocardial injury during ischemia and reperfusion. Impaired AMPK activation in the heart compromises ischemic glucose transport, impairs post-ischemic contractile function and exacerbates necrosis and apoptosis during ischemia-reperfusion. We have also recently introduced a novel paradigm for AMPK activation, based on our discovery that the cytokine macrophage migration inhibitory factor (MIF) has an autocrine/paracrine effect to amplify AMPK activation during ischemia. Isolated hearts from MIF knockout mice have impaired AMPK activation and poor ischemic tolerance, suggesting that MIF has a physiological role in the response to ischemia. These results have potential clinical importance, since we also found that a common polymorphism in the MIF promoter leads to impaired MIF secretion and AMPK activation during hypoxia in human cells. The proposed experiments will build on our prior research and address key new questions that will elucidate the regulation of the AMPK pathway and its potential for therapeutic application. We will 1) determine the molecular signal transduction mechanisms through which MIF activates AMPK and the specific role of cardiomyocte-derived MIF during ischemia, 2) define the roles of the tumor suppressing kinase LKB1 and calcium calmodulin-activated protein kinase kinase (CaMKK2) in AMPK activation in the ischemic heart and 3) develop therapeutic approaches with novel AMPK activators to protect the heart against ischemic injury. The experiments outlined in the current proposal utilize innovative cellular, molecular, genetic and physiologic approaches that we have developed during the prior funding period. They draw on the investigators' combined expertise in the areas of cellular cardiac metabolism, ischemic heart disease, MIF biology and inflammatory disease. Through the combined use of pharmacologic reagents and genetic models, the proposed experiments will determine whether activation of AMPK is an effective strategy to protect the heart against ischemic injury. Thus, the proposed research aims to define novel biological aspects of ischemic heart disease and incorporates translational strategies that have promise to lead to novel treatment strategies for patients with coronary artery disease. PUBLIC HEALTH RELEVANCE: People with hardening of the arteries or coronary artery disease can develop heart attacks from a lack of blood flow and oxygen delivery to their heart muscle. The purpose of this research is to identify key molecules in the heart that can prevent damage during a heart attack. We propose to develop novel strategies, directed at these molecules, that may lead to the development of new treatments for patients with coronary artery disease.