Unravelling the mechanistic basis of age-related mitochondrial membrane reorganizations in the ascomycete Podospora anserina

线粒体是具有许多重要功能的真核细胞器（例如ATP生成，铁/硫簇的生物合成）。因此，功能损伤导致变性、各种疾病的发展和生物衰老。我们使用丝状子囊菌鹅足孢作为一种成熟的衰老模型，具有强大的线粒体衰老病因学。在衰老过程中，鹅绒鸡线粒体DNA发生重组，线粒体形态和超微结构发生明显变化。在dfg支持的项目的第一阶段，我们专注于线粒体f1fo - atp合酶在线粒体嵴超微结构形成中的作用。我们通过实验验证了一个模型，该模型依赖于早期的电子冷冻断层扫描数据，表明f1fo - atp合成酶二聚体的年龄相关解离是衰老过程中板层线粒体向泡状线粒体转变的原因。f1fo - atp合成酶二聚体是嵴尖端形成所必需的。我们证明了atp合成酶亚基e和g参与了典型嵴的形成。我们还发现，亚基e编码基因的缺失可诱导线粒体自噬（mitophagy），从而潜在地补偿两种f1fo - atp合成酶二聚体组装因子的消融所造成的损伤。在该项目的第二个阶段，我们现在计划集中在两个主要主题上，这两个主题将填补与线粒体生物发生有关的途径网络中现有的空白，这些途径具有最有效的功能。在第一个子项目中，我们将特别强调自噬在线粒体中所起的作用，线粒体在F1Fo atp合酶二聚体形成中受损。第二个子项目将研究MICOS（“线粒体接触位点和嵴组织系统”）的作用，MICOS是一种大分子蛋白质复合物，参与嵴连接的形成。在线粒体超微结构的年龄相关变化过程中，需要对MICOS进行重建。我们首先将分析该复合体在猪绒球菌中的组成，并分别生成和分析两个核心亚基PaMIC10和PaMIC60丰度被调节（即敲除和过表达）的菌株。随后，我们将通过实验分析MICOS在线粒体内膜年龄相关重塑中的作用。这两个子项目都依赖于一组有希望的数据和在第一个供资期间制定的实验先决条件。总的来说，我们将对生物系统衰老过程中涉及线粒体动态重组的成分和机制产生先进的新见解。

Mitochondria are eukaryotic cell organelles with a number of important functions (e.g ATP generation, biosynthesis of Fe/S clusters). Accordingly, functional impairments lead to degeneration, the development of different diseases and to biological aging. We use the filamentous ascomycete Podospora anserina as a well-established aging model with a strong mitochondrial etiology of aging. During aging of P. anserina gross reorganizations of the mitochondrial DNA and pronounced changes in mitochondrial morphology and ultrastructure occur. In the first period of the DFG-supported project we focused on the role of the mitochondrial F1Fo-ATP-synthase in shaping the ultrastructure of mitochondrial cristae. We experimentally validated a model which relies on earlier electron cryotomography data suggesting that the age-associated dissociation of F1Fo-ATP-synthase dimers, which are essential for the formation of cristae tips, is responsible for the transition of lamellar to vesicular mitochondria during aging. We demonstrated that ATP-synthase subunits e and g are involved in formation of typical cristae. We also showed that deletion of the gene coding for the subunit e induces bulk and mitochondrial autophagy (mitophagy) and thereby potentially compensates impairments caused by the ablation of the two F1Fo-ATP-synthase dimer assembly factors. In a second period of the project we now plan to concentrate on two main topics that will close existing gaps in the network of pathways involved in the biogenesis of mitochondria with most efficient functions. In the first subproject we will put special emphasis on the role of autophagy in strains with mitochondria which are impaired in F1Fo ATP-synthase dimer formation. The second subproject will investigate the role of MICOS (“mitochondrial contact site and cristae organizing system”), a macromolecular protein complex involved in the formation of cristae junctions. During the age-associated changes in mitochondrial ultrastructure MICOS needs to be remodeled. We first will analyze the composition of this complex in P. anserina and generate and analyze strains with modulated abundance (i.e. knockout and overexpression) of the two core subunits PaMIC10 and PaMIC60, respectively. Subsequently, we will experimentally analyze the role of MICOS in age-associated remodeling of the inner mitochondrial membrane. Both subprojects rely on a body of promising data and on experimental prerequisites elaborated in the first funding period. Overall, we will generate advanced new insights into components and mechanisms involved in the dynamic reorganization of mitochondria during aging of biological systems.