Mechanistic insights into the cardioprotective effects of mABC1 protein

项目简介/摘要申请人Hossein Ardehali，医学博士，2004年在约翰霍普金斯医院完成住院医师和研究员培训，此后一直担任西北大学医学、分子药理学和生物化学助理教授。他刚刚完成了K08奖助金（2005年获得资助，优先级得分为120），并在2007年获得了R01奖助金，优先级得分为第4百分位。候选人对在学术机构中从事基础科学研究和患者护理有浓厚的兴趣，西北大学已经并将继续提供良好的支持环境。Ardehali博士的长期目标是成为心脏生物学领域的成功研究者，并将基础科学发现应用于临床实践，希望开发缺血性心脏病的新疗法。该提案详细介绍了Ardehali博士的研究职业发展计划，该计划整合了四个目标：1)参加科学充实计划，2)建立基于他的临床和科学优势的独特研究领域，3)提高实验室的方法能力，4)培养与该领域领先科学家的合作。申请人的主要重点是一种新型线粒体蛋白的功能表征，线粒体atp结合盒蛋白1 （mABC1）。申请人已经证明，mABC1的过表达可防止细胞死亡，但该蛋白的主要功能尚不清楚。申请人实验室最近的结果表明，分离心肌细胞中mABC1的下调导致线粒体铁的增加和细胞内含铁硫簇（Fe/S）蛋白质活性的降低。他还培育了心脏特异性mABC1基因敲除（KO）和转基因（TG）动物。心脏特异性mABC1 KO导致线粒体铁积累并导致心肌病的发展，而mABC1 TG小鼠对阿霉素诱导的心脏毒性具有抗性，线粒体铁水平较低。综上所述，这些结果表明mABC1参与线粒体铁稳态和铁/硫团簇的线粒体外运输，并且该蛋白在心脏中的过度表达可防止阿霉素诱导的心脏毒性。该建议的中心假设是mABC1受mTOR通路调节，mABC1的心脏保护作用是通过减少自噬和改善线粒体的生物发生和功能来实现的。在Aim 1中，申请人将评估mTOR通路对mABC1的调控。在Aim 2中，将评估mABC1调节对细胞铁通量的影响，Aim 3将通过研究线粒体功能和自噬对mABC1调节的响应来评估mABC1细胞保护作用的机制。提出的研究是合乎逻辑的和引人注目的实验序列，旨在跟进我们的关键观察，即mABC1对细胞死亡具有保护作用，并在线粒体铁稳态和铁/S集群输出线粒体中发挥作用。

DESCRIPTION (provided by applicant): The Project Summary/Abstract The applicant, Hossein Ardehali, M.D., Ph.D., completed his residency and fellowship training at The Johns Hopkins Hospital in 2004 and has been an Assistant Professor of Medicine, Molecular Pharmacology and Biological Chemistry at Northwestern University since then. He just completed a K08 grant (funded in 2005 with a priority score of 120), and has an active R01 grant that was funded in 2007 with a score of 4th percentile. The candidate has a solid interest in pursuing basic science research along with patient care in an academic institution, and Northwestern has and will continue to provide an excellent supportive environment. Dr. Ardehali's long term goals are to become a successful investigator in the field of cardiobiology and to apply basic science discoveries to clinical practice with the hope of developing new treatments for ischemic heart disease. This proposal details Dr. Ardehali's research career development plan that integrates four objectives: 1) to attend scientific enrichment programs, 2) to establish distinct areas of research that builds upon his clinical and scientific strengths, 3) to improve the methodological capability of the lab, and 4) to cultivate collaboration with leading scientists in the field. The applicant's major focus is on functional characterization of a novel mitochondrial protein, mitochondrial ATP-binding cassette protein 1 (mABC1). The applicant had shown that overexpression of mABC1 leads to protection against cell death, but the primary function of the protein is not known. Recent results from the applicant's lab indicate that downregulation of mABC1 in isolated cardiomyocytes results in an increase in mitochondrial iron and a reduction in the activity of cytosolic iron-sulfur cluster (Fe/S) containing proteins. He has also generated cardiac specific mABC1 knockout (KO) and transgenic (TG) animals. Heart specific mABC1 KO results in mitochondrial iron accumulation and leads to the development of cardiomyopathy, while mABC1 TG mice are resistant to doxorubicin-induced cardiotoxicity and have lower mitochondrial iron levels. Together, these results suggest that mABC1 is involved in mitochondrial iron homeostasis and the transport of Fe/S clusters out of the mitochondria, and overexpression of the protein in the heart protects against doxorubicin induced cardiotoxicity. The central hypothesis of this proposal is that mABC1 is regulated by mTOR pathway and that the cardioprotective effects of mABC1 are through a reduction in autophagy and an improvement in mitochondrial biogenesis and function. In Aim 1, the applicant will evaluate regulation of mABC1 by mTOR pathway. In Aim 2, the effects of mABC1 modulation on cellular iron flux will be assessed, and Aim 3 will evaluate the mechanism for the cytoprotective effects of mABC1 by studying mitochondrial function and autophagy in response to mABC1 modulation. The proposed studies are logical and compelling sequence of experiments designed to follow up on our key observation that mABC1 is protective against cell death and plays a role in mitochondrial iron homeostasis and Fe/S cluster export out of mitochondria. PUBLIC HEALTH RELEVANCE: Project narrative Iron is a required component of heart cells and is essential for their baseline function. We have shown that a protein called mABC1 is protective against cardiac cell death and plays a role in regulating mitochondrial iron levels. Furthermore, mice that have high levels of mABC1 protein are protected against the toxic effects of the cancer drug doxorubicin. Here, we will study how mABC1 levels are regulated in the heart and will study the mechanism for its protective effects.