AMP-activated protein kinase in the ischemic heart

描述(申请人提供)：我们研究的总体目标是确定决定心脏对心肌缺血反应的细胞和分子机制，长期目标是为冠心病患者开发新的治疗方法。AMP激活的蛋白激酶(AMPK)是一种重要的细胞内信号通路，与包括缺血性心脏病、糖尿病和癌症在内的人类疾病密切相关。AMPK调节主要代谢途径、基因转录和线粒体生物发生。我们的实验室已经阐明了AMPK在心脏中的重要性，在那里它可以保护缺血和再灌注期间的心肌损伤。心脏AMPK活性受损损害了缺血葡萄糖的转运，损害了缺血后的收缩功能，加剧了缺血再灌流过程中的坏死和细胞凋亡。我们最近还引入了一种新的AMPK激活范式，基于我们发现细胞因子巨噬细胞移动抑制因子(MIF)在缺血时具有自分泌/旁分泌效应来放大AMPK的激活。MIF基因敲除小鼠的离体心脏AMPK活性受损，缺血耐受性差，提示MIF在对缺血的反应中具有生理作用。这些结果具有潜在的临床意义，因为我们还发现MIF启动子的一个常见多态性导致人类细胞在缺氧时MIF分泌和AMPK激活受损。拟议的实验将建立在我们之前的研究基础上，并解决关键的新问题，这些问题将阐明AMPK通路的调节及其治疗应用的潜力。我们将1)确定MIF激活AMPK的分子信号转导机制和心肌细胞来源的MIF在缺血时的特殊作用；2)确定肿瘤抑制蛋白LKB1和钙钙调素激活的蛋白激酶2在缺血心脏AMPK激活中的作用；3)开发新型AMPK激动剂的治疗方法，以保护心脏免受缺血损伤。目前提案中概述的实验利用了我们在前一个资助期开发的创新细胞、分子、遗传和生理学方法。他们利用了研究人员在细胞心脏代谢、缺血性心脏病、MIF生物学和炎症性疾病等领域的综合专业知识。通过联合使用药理试剂和遗传模型，拟议的实验将确定激活AMPK是否是保护心脏免受缺血损伤的有效策略。因此，这项拟议的研究旨在定义缺血性心脏病的新生物学方面，并纳入有望为冠心病患者带来新的治疗策略的翻译策略。与公共卫生相关：患有动脉硬化或冠状动脉疾病的人可能会因缺乏血液流动和向心肌输送氧气而发生心脏病发作。这项研究的目的是确定心脏中可以防止心脏病发作期间受损的关键分子。我们建议针对这些分子开发新的策略，这可能会导致冠心病患者的新治疗方法的开发。

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.