A conserved module required for mitochondrial function and viability under stress

描述（由申请人提供）：进行性线粒体氧化损伤和功能障碍是许多人类疾病发病的基础。利用酵母模型系统，我们已经证明，在线粒体应激条件下，线粒体招募了新的蛋白质寿命相关的线粒体应激反应1 （Lms1）。当Lms1被耗尽时，氧化应激会导致呼吸功能丧失，并随着时间的推移显著加速生存能力的丧失。Lms1在体内与Cdc48结合，Cdc48是一种atp酶，参与内质网（ERAD途径）蛋白质的反转录和降解。这些观察结果已经扩展到秀丽隐杆线虫，其中Lms1的敲低导致过氧化物敏感性和寿命缩短，氧化应激诱导细胞质到线粒体易位。我们认为Lms1是一个重要的泛真核系统的组成部分，可以保护细胞免受氧化应激和线粒体功能障碍的致命影响。我们假设它能感知线粒体应激，并通过Cdc48的募集，对错误折叠或受损的线粒体蛋白进行降解。我们在此提议确定：1)调节Lms1线粒体易位的机制。我们将确定：1)线粒体功能障碍信号的位置和特异性；2)如何将该信号中继到Lms1；3) Lms1线粒体受体的身份。II) Lms1在保持线粒体活性和活力方面的功能。我们将：1)全面鉴定Lms1- Cdc48配合物的组分；2)确定Lms1-Cdc48相互作用的性质和调控；3)了解在lms1突变体中观察到的线粒体缺陷。哺乳动物Lms1的调控和功能。我们将：1)使用培养细胞检查哺乳动物Lms1的调节和功能；2)使用Lms1-/-小鼠，确定该蛋白在维持线粒体功能中的生理作用，特别是在心肌细胞中。

DESCRIPTION (provided by applicant): Progressive mitochondrial oxidative damage and dysfunction is fundamental to the pathogenesis of many human diseases. Using a yeast model system, we have shown that the novel protein Lifespan-associated Mitochondrial Stress-responsive 1 (Lms1) is recruited to mitochondria under conditions of mitochondrial stress. When Lms1 is depleted, oxidative stress induces loss of respiratory function and markedly accelerated loss of viability over time. Lms1 associates in vivo with Cdc48, an ATPase integral to the retrotranslocation and degradation of proteins from the endoplasmic reticulum (ERAD pathway). These observations have been extended to C. elegans, wherein knockdown of Lms1 leads to peroxide sensitivity and decreased lifespan and oxidative stress induces cytosol to mitochondria translocation. We propose that Lms1 is a component of an important pan-eukaryotic system for protection from the lethal effects of oxidative stress and mitochondrial dysfunction. We hypothesize that it senses mitochondrial stress and, through Cdc48 recruitment, enacts the degradation of misfolded or damaged mitochondrial protein. We hereby propose to determine: I) The mechanisms regulating Lms1 mitochondrial translocation. We will determine: 1) the location and specificity of the mitochondrial dysfunction signal; 2) how this signal is relayed to Lms1; and 3) the identity of the Lms1 mitochondrial receptor. II) The function of Lms1 in preserving mitochondrial activity and viability. We will: 1) comprehensively identify the components of the Lms1- Cdc48 complex; 2) determine the nature and regulation of the Lms1-Cdc48 interaction; and 3) understand the mitochondrial defect observed in the lms1 mutant. III) Lms1 regulation and function in mammals. We will: 1) examine mammalian Lms1 regulation and function using cultured cells; and 2) using an Lms1-/- mouse, determine the physiological role of this protein in maintaining mitochondrial function, particularly in cardiomyocytes. PUBLIC HEALTH RELEVANCE: Many human diseases are caused by a progressive deterioration of the function of mitochondria. We have discovered a widespread cellular system that acts to prevent this type of deterioration and have shown that it protects both yeast and nematodes from certain types of damage. We suggest that it will be equally important in humans and propose to further understand its biochemical and physiological role.