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：我是威廉S.米德尔顿纪念退伍军人管理局和医学助理教授 在威斯康星州大学医学和公共卫生学院。我在西北大学获得医学博士学位 大学毕业，在约翰霍普金斯医院完成内科住院医师实习，在 匹兹堡大学在我的奖学金培训期间，我专门在博士的实验室额外的时间。 Ferhaan Ahmad研究遗传性心肌病的机制，这最终导致了对 缺血再灌注损伤的心脏保护机制，由于我的临床兴趣，介入 心脏病学我被招募到威廉·S米德尔顿纪念弗吉尼亚州和威斯康星州大学提供 增加了对退伍军人患者的介入心脏病学覆盖，但也继续我在心脏保护方面的工作 提供启动资金、机构指导和实验室资源。 研究项目：线粒体K+通量的激活在缺血性损伤模型中赋予心脏保护作用。的 调节K+通量的潜在通道，即假定的线粒体ATP敏感性钾通道 （mitoKATP）与心脏保护最密切相关。然而，mitoKATP的分子身份是未知的， 代表了知识的关键差距，以发现靶向线粒体K+循环的疗法。先前研究 我的初步数据为磺酰脲受体2A的一个短的55 kDa剪接变体提供了证据 （SUR 2A-55）靶向线粒体，调节mitoKATP活性，使葡萄糖代谢增加， 当过表达时，保护心脏免受缺血-再灌注损伤。此外，先前的研究和我的 初步数据表明，肾脏外髓K+通道（ROMK）在线粒体ATP敏感性 K+转运和心脏保护。在该提案中，我们假设SUR 2A-55与ROMK 2结合， 形成心脏mitoKATP通道，通过激活线粒体K+循环阻断缺血性损伤 和增强葡萄糖代谢。通过靶向线粒体和心肌底物利用， SUR 2A-55代表了缺血性心脏病治疗的新靶点。我们建议对此进行调查 有三个具体目标的假设。具体目标1：确定SUR 2A-55是否与心脏中的ROMK相关 线粒体的钾通道。免疫亲和富集-质谱联用 将用于检查SUR 2A-55和ROMK 2之间的潜在关联。具体目标2：确定是否 心脏ROMK功能的丧失阻止了mitoKATP的激活和心脏保护。我们将测试 ROMK的药理学抑制或基因敲低阻止了mitoKATP的激活， 缺血预适应具体目标3：检查TGSUR 2A-55小鼠如何利用代谢底物， 在局部缺血过程中对葡萄糖的利用优于脂肪酸是否有助于心脏保护。 将评估静息和缺血后离体悬心的葡萄糖和脂肪酸代谢 在TGSUR 2A-55和WT小鼠中。 职业规划：我的长期职业目标是成为一名独立资助的VA医生，科学家， 通过靶向心脏线粒体和代谢治疗缺血性心脏病领域的领导者。我 VA的主要研究导师Nihal Ahmad博士将指导我的进展和培训。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。从这个VA的结果 CDA将为我提供初步数据和研究经验，以制定具有竞争力的MERIT评审 建议进一步开发缺血性心脏病的新治疗靶点。 环境：我将在弗吉尼亚州和威斯康星州大学完成拟议的研究。两 组织提供了一个非常友好的氛围和强大的机构支持，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.