Structure, Turnover and Safeguard of Mitochondria

摘要 线粒体是控制细胞生死的重要细胞器。线粒体高度集中在 动态：它们生长、分裂和融合，当它们最终被破坏时，经历退化 线粒体分裂是由动力蛋白相关的GTPase，Drp1介导的，而融合是由两个 动力蛋白相关的GTP酶、OPA1和丝裂原蛋白。这些GTP酶在人类疾病中发生突变，包括 神经发育障碍、夏科-玛丽-牙神经病和视神经萎缩。这些变化的活动 蛋白质还与代谢综合征、心血管疾病和与年龄有关的疾病有关 神经退行性变。我的实验室的目标是破译控制线粒体的分子机制 构建基础生物学并将其转化为疾病干预措施。在过去的二十年里，我们已经 鉴定和鉴定了膜融合和膜融合核心反应中三种基本的GTP酶 组织。线粒体动力学的作用正在不断扩大，现在包括大小控制 线粒体，它们的分布和周转，以及神经元、心肌细胞、干细胞和 免疫细胞。最近，线粒体分裂和融合的机制变得明显 比最初想象的要复杂得多，涉及细胞器间的相互作用和反馈反应 监测和调节它们的平衡。新兴的新生物学正在改变线粒体结构领域 和动态感。在接下来的5年里，我们将解决这一智力进化带来的重要问题。 首先，令我们惊讶的是，我们发现Drp1将内质网(ER)塑造成细管，形成 与线粒体收缩部位。DRP1产生的内质网-线粒体接触位点强烈促进 线粒体分裂。我们将研究Drp1是如何创建ER-线粒体接触位点的 特异性地作用于线粒体分裂，与内质网结合，并使内质网膜变形。 第二，我们发现了一条由Drp1控制的线粒体更新的生理途径，即Parkin/PINK1- 小鼠的独立有丝分裂吞噬。这条路径最上游的事件是识别和标记损坏 线粒体蛋白的泛素化。我们最初的实验表明，泛素化 发生在两个阶段-可逆的启动和承诺的扩增。我们将决定什么 泛素连接酶复合体如何识别和标记每一阶段的线粒体 体内线粒体受损。第三，我们发现了第一个感觉到压力反应(MitoSafe)的例子 并通过控制融合和分裂之间的平衡来调整线粒体结构。我们会 探讨MitoSafe的分子基础及其在小鼠体内的生理作用。米拉赠款将使 我们希望发现线粒体结构及其在体内的生理作用和调节的新逻辑。

Summary Mitochondria are essential organelles that control the life and death of cells. Mitochondria are highly dynamic: They grow, divide, and fuse, and when they eventually become damaged, undergo degradation Mitochondrial division is mediated by a dynamin-related GTPase, DRP1, while fusion is mediated by two dynamin-related GTPases, OPA1 and mitofusin. These GTPases are mutated in human diseases, including neurodevelopmental disorder, Charcot-Marie-Tooth neuropathy, and optic atrophy. Altered activities of these proteins have also been linked to metabolic syndrome, cardiovascular disease, and age-related neurodegeneration. My laboratory’s goal is to decipher the molecular mechanisms that control mitochondrial structure and translate the fundamental biology to disease interventions. In the past two decades, we have identified and characterized the three essential GTPases in the core reactions of membrane fusion and division. The roles of mitochondrial dynamics are ever-expanding, and now include size control of mitochondria, their distribution and turnover, and differentiation of neurons, cardiomyocytes, stem cells, and immune cells. Most recently, it became evident that the mechanisms of mitochondrial division and fusion are much more complex than initially imagined, involving inter-organelle interactions and a feedback response that monitors and tunes their balance. The emerging new biology is transforming the field of mitochondrial structure and dynamics. In the next 5 years, we will address the important questions raised by this intellectual evolution. First, to our surprise, we found that DRP1 shapes the endoplasmic reticulum (ER) into tubules that form contract sites with mitochondria. DRP1-produced ER-mitochondria contact sites strongly promote mitochondrial division. We will investigate how DRP1 creates ER-mitochondria contact sites that specifically function in mitochondrial division, associates with the ER, and deforms the ER membrane. Second, we discovered a physiological pathway of mitochondrial turnover via DRP1-controlled, Parkin/PINK1- independent mitophagy in mice. This pathway’s most upstream event is to recognize and mark damaged mitochondria by ubiquitination of mitochondrial proteins. Our initial experiments suggested that ubiquitination occurs in two phases – reversible initiation and committed amplification. We will determine what ubiquitinates mitochondria in each phase, and how the ubiquitin ligase complexes recognize and label damaged mitochondria in vivo. Third, we found the first example of a stress response (MitoSafe) that senses and adjusts the mitochondrial structure by controlling the balance between fusion and division. We will explore the molecular basis of MitoSafe and its physiological roles in mice. The MIRA grant will enable us to discover the new logics of mitochondrial structure and its physiological role and regulation in vivo.