The mechanism of cardio-protection from a sulfonylurea receptor isoform 2 splice variant (SUR2A-55) and its role in regulating ROMK activity, the putative mitochondrial ATP sensitive potassium channel

应聘者：我是退伍军人事务部威廉·S·米德尔顿纪念医院的心脏病专家和医学助理教授 在威斯康星大学医学和公共卫生学院。我在西北大学获得了医学博士学位 大学，并在约翰霍普金斯医院完成内科住院医师和心脏病学研究员 匹兹堡大学。在我的研究员培训期间，我把额外的时间花在了Dr。 Ferhaan Ahmad研究遗传性心肌病的机制，这最终导致了对 由于我对介入治疗的临床兴趣，缺血再灌注损伤中的心脏保护机制 心脏科。我被招募到威廉·S·米德尔顿纪念退伍军人管理局和威斯康星大学提供 扩大对退伍军人患者的介入心脏病学覆盖范围，同时继续我在心脏保护方面的工作 利用启动资金、机构指导和实验室资源。 研究项目：线粒体K+通量的激活在缺血损伤模型中提供心肌保护。的 调节K+流的潜在通道，可能是线粒体对ATP敏感的钾通道 (MitoKATP)与心脏保护关系最为密切。然而，mitoKATP的分子同一性尚不清楚， 代表了在发现针对线粒体K+循环的治疗方法方面的关键知识差距。先前的研究 我的初步数据为磺酰脲受体2A的短小55 kDa剪接变异体提供了证据 (SUR2A-55)，靶向线粒体，调节mitoKATP活性，促进葡萄糖代谢和 在过度表达时保护心脏免受缺血再灌注损伤。此外，以前的研究和我的 初步数据提示肾外髓质钾通道(ROMK)在线粒体ATP敏感性中的作用 钾离子转运与心脏保护。在本提案中，我们假设SUR2A-55与ROMK2结合以 形成心脏mitoKATP通道，通过激活线粒体K+循环来阻断缺血性损伤 和增强葡萄糖代谢。通过以线粒体和心肌底物利用为目标， SUR2A-55是治疗缺血性心脏病的新靶点。我们建议对此进行调查 有三个具体目标的假设。特定目标1：确定SUR2A-55是否与心脏ROMK相关 形成线粒体K+通道。免疫亲和富集质谱联用 将用于研究SUR2A-55和ROMK2之间的潜在关联。具体目标2：确定 心脏ROMK功能的丧失阻止了线粒体KATP的激活和心脏保护。我们将测试一下 ROMK的药物抑制或基因敲除可阻止mitoKATP的激活和保护 缺血预适应。具体目标3：研究TGSUR2A-55小鼠如何利用代谢底物和 在缺血期间优先利用葡萄糖而不是脂肪酸是否有助于心脏保护。 将评估静息和缺血后离体悬吊心脏的葡萄糖和脂肪酸代谢 TGSUR2A-55和WT小鼠。 职业规划：我的长期职业目标是成为一名独立资助的退伍军人管理局内科医生兼科学家 通过靶向心肌线粒体和新陈代谢治疗缺血性心脏病领域的领导者。我的 退伍军人管理局的主要研究导师Nihal Ahmad博士将指导我的进步和培训。我的其他导师和 合作者将提供培训，以实现我的研究目标和职业目标。这次退伍军人管理局的结果 CDA将为我提供初步数据和研究经验，以制定竞争优势评估 建议进一步开发治疗缺血性心脏病的新靶点。 环境：我将在退伍军人管理局和威斯康星大学完成拟议的研究。两者都有 各组织提供特别的合议性氛围和强有力的机构支持，包括 实验室资源、设备和核心设施。

Candidate: I am a staff cardiologist at the William S. Middleton Memorial VA and Assistant Professor of Medicine at the University of Wisconsin School of Medicine and Public Health. I obtained my MD from Northwestern University and completed internal medicine residency at Johns Hopkins Hospital and cardiology fellowship at the University of Pittsburgh. During my fellowship training I dedicated additional time in the laboratory of Dr. Ferhaan Ahmad to study mechanisms of genetic cardiomyopathies, which eventually led to the study of cardioprotective mechanisms in ischemia reperfusion injury due to my clinical interest in interventional cardiology. I was recruited to the William S. Middleton Memorial VA and University of Wisconsin to provide increased interventional cardiology coverage to Veteran patients but to also continue my work in cardioprotection with start-up funds, institutional mentorship and laboratory resources. Research Project: Activation of mitochondrial K+ flux confers cardioprotection in models of ischemic injury. Of the potential channels that modulate K+ flux, the putative mitochondrial ATP-sensitive potassium channel (mitoKATP) is most closely related to cardioprotection. However the molecular identity of mitoKATP is unknown and represents a critical gap in knowledge to discover therapies that target the mitochondrial K+ cycle. Prior studies and my preliminary data provide evidence for a short 55 kDa splice variant of the sulfonylurea receptor 2A (SUR2A-55) that targets mitochondria, regulates mitoKATP activity, enables increased glucose metabolism and protects the heart from ischemia-reperfusion injury when overexpressed. In addition, prior studies and my preliminary data suggest a role for the renal outer medullary K+ channel (ROMK) in mitochondrial ATP sensitive K+ transport and cardioprotection. In this proposal we hypothesize that SUR2A-55 combines with ROMK2 to form a cardiac mitoKATP channel that blocks ischemic injury by activating the mitochondrial K+ cycle and enhancing glucose metabolism. By targeting both mitochondria and myocardial substrate utilization, SUR2A-55 represents a novel target in the treatment of ischemic heart disease. We propose to investigate this hypothesis with three specific aims. Specific Aim 1: Determine if SUR2A-55 associates with ROMK in cardiac mitochondria to form a mitochondrial K+ channel. Immuno-affinity enrichment coupled with mass spectroscopy will be used to examine potential associations between SUR2A-55 and ROMK2. Specific Aim 2: Determine if the loss of function of cardiac ROMK prevents activation of mitoKATP and cardioprotection. We will test whether pharmacologic inhibition or genetic knockdown of ROMK prevents activation of mitoKATP and protection from ischemic preconditioning. Specific Aim 3: Examine how TGSUR2A-55 mice utilize metabolic substrates and whether a preference for glucose utilization over fatty acids during ischemia contributes to cardioprotection. Glucose and fatty acid metabolism from isolated hanging hearts during rest and after ischemia will be assessed in TGSUR2A-55 and WT mice. Career Plan: My long-term career goal is to become an independently funded VA physician-scientist who is a leader in the field of treating ischemic heart disease by targeting cardiac mitochondria and metabolism. My primary VA research mentor, Dr. Nihal Ahmad, will guide my progress and training. My additional mentors and collaborators will provide training to accomplish my research aims and career goals. The results from this VA CDA will provide me with the preliminary data and research experience to formulate a competitive MERIT Review proposal to further develop novel therapeutic targets for ischemic heart disease. Environment: I will complete the proposed research at the VA and the University of Wisconsin. Both organizations provide an exceptionally collegial atmosphere and strong institutional support that include laboratory resources, equipment, and core facilities.