Molecular Mechanisms of Mitochondrial Ca2+ Transport

线粒体钙摄取是能量代谢、细胞信号和动力学的核心，但 对潜在的分子机制和生理学的探索才刚刚开始 孔道形成蛋白MCU和EF手蛋白MICU1的发现 钙离子转运蛋白的关键调节因子，表现出显著的协同进化和协同表达。 最近，MICU2/3，MICU1的Paralog of MICU1，MCUb，MCU的显性否定形式，Emre，And 还描述了用于MCU的适配器和单板车的另一调节器MCUR1。 尽管有一个持久而巨大的驱动力支持线粒体钙摄取，但有一个 [Ca~(2+)]对单一转运体(MTCU)电流的严格而复杂的调节。胞质钙离子 对MCU的敏感性是由MICU通过其EF手授予的。我们和其他人的工作 提供证据表明，需要MICU1来保持MCU在亚微摩尔细胞质中的闭合 [Ca~(2+)]([Ca~(2+)]c)，并促进协作式MCU以更高的[Ca~(2+)]c.开放。 年项目期间，我们已经建立了第一个MICU1小鼠模型并进行了演示 MICU1缺失增加了对线粒体钙超载和细胞死亡的敏感性 无论是在体内还是体外。重要的是，与MICU1功能丧失相关的人类疾病 在许多患者中也有报道。因此，对转导作用的机制的描述 MTCU的功能意义和药理靶向是 意义重大。此外，由于我们团队中相关技能的补充，以及我们的 以往在单行商研究方面的成功和强大的工具包，我们是唯一有资格的 在这一区域移动操纵杆。我们的假设是：(1)MICU1使用3种不同的相互作用 与MCU、EmRE和MICU结合的部位，以传递钙离子的影响，从而控制跨膜离子通量 MTCU，(2)MTCU组分的相对表达水平的差异决定 MTCU的组织特异性区分钙敏感性和药理性质，(3)在 MICU1基因缺陷小鼠的肝脏和大脑，对生理刺激和 守门能力受损会明显影响对各种压力条件的反应 和MTCU的协同激活。对这些想法的测试将提供线索 控制MTCU的基本机制，潜在的药物靶点和 发病机制是由MTCU成分的扰动引起的。研究将利用这两种方法 新的人类和小鼠遗传模型和成像方法。

Mitochondrial Ca2+ uptake is central to energy metabolism, cell signaling and dynamics but exploration of the underlying molecular mechanisms and physiology has just started with the discovery of MCU, a pore-forming protein and MICU1, an EF-hand protein described as a critical regulator of the Ca2+ uniporter, which display striking co-evolution and co-expression. Recently, MICU2/3, paralogs of MICU1, MCUb, a dominant negative form of MCU, EMRE, an adaptor for MCU, and MCUR1, another regulator of the uniporter have also been described. Although a permanent and huge driving force supports mitochondrial Ca2+ uptake, there is a strict and complex regulation of the uniporter (mtCU) current by [Ca2+]. Cytoplasmic Ca2+ sensitivity to the MCU is conferred by MICUs via their EF hands. Work by us and others provided evidence that MICU1 is needed to keep the MCU closed at submicromolar cytoplasmic [Ca2+] ([Ca2+]c) and to promote co-operative MCU opening at higher [Ca2+]c. In the past <1.5 year project period, we have established the first mouse model for MICU1 and demonstrated that deletion of MICU1 increases the sensitivity to mitochondrial Ca2+ overload and cell death both in vivo and in vitro. Importantly, human disease associated with MICU1 loss of function has also been described in many patients. Thus, delineation of the mechanism relaying the effect of Ca2+ to the pore, and the functional significance and pharmacological targeting of mtCU are of vast significance. Moreover, because of complementing relevant skills in our group, and our previous success in and powerful toolkit for the study of the uniporter, we are uniquely qualified to move the stick in this area. Our hypotheses are that (1) MICU1 employs 3 distinct interaction sites for binding MCU, EMRE, and MICUs to relay the effect of Ca2+ to control the ion flux across the mtCU, (2) differences in the relative expression level of the mtCU components determine the tissue specific differential Ca2+ sensitivity and pharmacological properties of the mtCU, (3) in the liver and (4) the brain of MICU1-deficient mice, responses to physiological stimulation and responses to various stress conditions can be distinctively affected by impaired gatekeeping and cooperative activation of the mtCU, respectively. Testing of these ideas will provide clues to the fundamental mechanism controlling mtCU, to potential drug targets and to the pathogenesis initiated by perturbation of the mtCU constituents. The studies will utilize both novel human and murine genetic models and imaging methods.