Molecular Mechanisms of Mitochondrial Ca2+ Transport

线粒体Ca 2+摄取是能量代谢、细胞信号传导和动力学的中心， 对潜在的分子机制和生理学的探索才刚刚开始， 发现MCU，一种孔形成蛋白和MICU 1，一种EF-手蛋白，被描述为 Ca 2+单向转运体的关键调节子，其显示出显著的共进化和共表达。 最近，MICU 2/3，MICU 1的旁系同源物，MCUb，MCU的显性阴性形式，EMRE， MCU适配器和另一种单向传输器调节器MCUR 1也作了描述。 虽然一个永久的和巨大的驱动力支持线粒体Ca 2+的摄取， [Ca 2 +]对单向转运体（mtCU）电流的严格和复杂的调节。细胞质ca 2 + 对MCU的灵敏度由MICU通过其EF指针赋予。我们和其他人的工作 提供的证据表明，需要MICU 1来保持MCU在亚微摩尔细胞质中关闭， [Ca2+]（[Ca 2 +]c），并在较高的[Ca 2 +]c下促进协同MCU开放。过去<1.5 在为期一年的项目期间，我们建立了第一个MICU 1小鼠模型，并证明了 MICU 1的缺失增加了对线粒体Ca 2+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MICU 1功能丧失相关的人类疾病 在许多患者中也有描述。因此，描绘的机制中继的影响， 钙离子进入孔道，mtCU的功能意义和药理靶向作用， 巨大的意义此外，由于我们小组的相关技能互补， 以前的成功和强大的工具包为uniporter的研究，我们是唯一合格的 在这个区域移动操纵杆。我们的假设是：（1）MICU 1采用3种不同的相互作用 结合MCU、EMRE和MICU的位点，以传递Ca 2+的作用，从而控制离子通量穿过 （2）mtCU组分的相对表达水平的差异决定了 mtCU的组织特异性差异Ca 2+敏感性和药理学性质，（3）在 肝脏和（4）MICU 1缺陷小鼠的大脑，对生理刺激的反应， 对各种压力条件的反应可以明显地受到受损的守门能力的影响 和协作激活mtCU。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， 由mtCU成分的扰动引发的发病机制。研究将利用这两个 新的人和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.