神经细胞中C3orf23调控酮戊二酸脱氢酶的作用与机制研究

Mitochondrial dysfunction is a common feature of multiple neurodegenerative diseases, while oxoglutarate dehydrogenase (OGDH) complex is a rate-limiting metabolic enzyme in mitochondria. This enzyme complex generates the majority of reactive oxygen species (ROS), while ROS hinders its activity. The reduction of OGDH complex activity is tensely correlated with the progress of neurodegenerative diseases, while mutations in its subunits and interacting proteins provide a route to neuronal dysfunctions. Despite its importance in mitochondrial metabolism and diseases, we still lack insight into the specific regulatory mechanism of this protein complex..Through an unbiased proteomics approach to characterize OGDH complex interactome, we identified a novel OGDH-specific binding protein (C3orf23). We also have exemplified that C3orf23 is vital for OGDH activity. Moreover, we found this protein to be predominantly expressed in pallium and cerebellum. All in all, our preliminary data implicates a novel regulatory mechanism of C3orf23 upon OGDH..To further elucidate how C3orf23 regulates OGDH activity in neural cells, we set forth four research objectives: 1. To illustrate how C3orf23 modulates OGDH activity by using a quantitative proteomics approach and biochemistry studies in vivo and in vitro. 2. To investigate how this regulation impacts mitochondrial and cell metabolism through a metabolomics and enzymology experiments approach with the use of cells and mouse tissue. 3. To examine how aging and neurodegenerative diseases impact this regulation using mouse models. 4. To uncover the binding structures of C3orf23 and OGDH..This proposed study will fortify our understanding of the regulatory mechanism of OGDH. It holds the potential to uncover procedures that could enhance OGDH activity in aging and neurodegenerative diseases.

线粒体能量代谢水平在神经退行性疾病中普遍降低，而酮戊二酸脱氢酶复合体（OGDHC）是线粒体中影响能量代谢的重要限速酶，其功能异常与认知障碍和神经退行性疾病密切相关。我们前期实验发现在神经系统中高表达的C3orf23能够特异性地与OGDH结合，并调节OGDHC的功能。我们推测在神经系统中高表达的C3orf23通过与OGDHC结合，保持OGDHC的活性，从而调节神经细胞中线粒体的代谢活性。为了深入研究该调节机制及其在神经细胞中的作用，在本课题中我们将研究以下科学问题：1.C3orf23如何调节OGDHC功能？2.C3orf23通过OGDHC影响神经细胞线粒体的哪些功能？3.神经细胞中影响C3orf23-OGDHC相互作用的因素有哪些？4.C3orf23蛋白与OGDH相互作用的结构基础是什么？这些研究将揭示一种调节酮戊二酸脱氢酶复合体功能的新机制；加深对于中枢神经系统中代谢调控的认识。

线粒体蛋白稳态是维持线粒体功能的重要分子机制，DNAJ/HSP40蛋白家族介导HSP70特异性的底物识别从而维持蛋白稳态。通过系统性的蛋白互作分析，我们发现了一个全新的线粒体DNAJ蛋白，也是线粒体内腔中发现的唯一的DNAJC 家族蛋白：TCAIM。该蛋白与酮戊二酸脱氢酶复合体E1亚基(OGDH)特异性的结合。有趣的是，尽管绝大多数DNAJ家族蛋白成员通过介导HSP70与其特异性底物相互作用是帮助底物蛋白的折叠；生物化学、酶学、代谢组学和结构生物的数据却显示：TCAIM对OGDH的作用是介导对正常折叠的OGDH蛋白的特异性降解。这一特殊的机制尚属首次被发现。在该研究的过程中，我们也发现TCAIM在线粒体谷氨酰胺代谢中的重要作用，并因此进一步影响肝脏和神经的代谢。拟在后续研究中进一步深入解析TCAIM的生物学功能