呼吸链复合物中核编码亚基和线粒体编码组分之间的动态表达偶联和化学计量平衡调控对于线粒体稳态的维持至关重要。然而，业界对于相关过程的调控机制和具体的功能关联尚知之甚少。近期的研究结果显示，呼吸链复合物IV的核编码亚基COX4可以调节线粒体编码组分COX1的翻译。而我们发现PET117蛋白会影响COX4对COX1表达的调控作用。我们的预数据还显示，COX4与PET117之间存在相互作用和调控关系。另外，PET117-KD或者PET117-KO会降低COX1蛋白水平。 因此，PET117可能是COX4调节COX1表达的过程中一个关键的介导者。在本项目中，我们将对体外和在体水平PET117的生物学功能及其在COX4与COX1表达协调过程中的调节作用做进一步的研究，以期发现调控核编码基因和线粒体编码基因的表达互作的新机制，为解析线粒体功能稳态调控机理和线粒体相关疾病的分子病因提供重要线索。

Dynamically coordinated expression and balanced stoichiometric production of respiratory chain complex subunits， encoded by nuclear genome and mitochondrial DNA， is very essential for the maintenance of mitochondrial homeostasis. However, our current understanding of the underlying regulatory mechanism(s) and the functional relevance is still very limited. Recent studies demonstrated that the nulear-encoded COX4 protein, one subunit of Complex IV, can modulate the translation of its mitochondrial-encoded counterpart protein COX1. In our investigation, we found that a mitochondrial protein PET117 can affect the regulatory effect(s) of COX4 protein on COX1 expression. Our preliminary data also indicated that COX4 can interact with and regulate PET117. We found that either PET117-KD or PET117-KO in the cells can cause down regulation of COX1 protein. Together, we hypothesize that PET117 protein may function as a key factor mediating the regulatory effects of COX4 on COX1 expression. In the proposed study, we will further characterize the in vitro and in vivo biological functions of PET117 protein, as well as its role（s） in mediating expression coordination between COX4 and COX1, and try to uncover previously unrecognized regulatory mechanism(s) underlying nuclear-mitochondrial gene expression coupling. Our study would offer important insights and contribute to deciphering the mechanisms of mitochondrial homeostasis and molecular etiology of mitochondrial diseases.