人类线粒体ClpXP蛋白酶底物的鉴定及其对Perrault综合征的意义

文献信息

中文摘要

ClpXP ATP依赖性解折叠酶-蛋白酶复合物在线粒体蛋白质稳态维持中发挥重要作用。已在Perrault综合征3型（PRLTS3）患者中鉴定出CLPP的致病性变异，该病是一种罕见的隐性线粒体疾病，以感音神经性听力损失、卵巢功能障碍和神经系统异常为特征。然而，这些ClpP变异如何导致该疾病仍不清楚。在此，我们通过对PRLTS3患者来源的成纤维细胞进行蛋白质组学分析，并结合诱导多能干细胞（iPSCs）及iPSC来源的神经祖细胞的后续研究以及体外生化实验，鉴定了ClpXP的三个细胞底物。这些底物是：CHCHD2，一种氧化磷酸化和线粒体应激反应的双细胞器调节因子；ALAS1，催化血红素生物合成的限速步骤；以及TFAM，一种必需的线粒体转录因子。ClpXP对这些底物的高效降解需要衔接蛋白PDIP38。我们提出，这些底物细胞水平的失调可能参与PRLTS3的病因学。

英文摘要

The ClpXP ATP-dependent unfoldase-protease complex plays important roles in maintaining protein homeostasis in the mitochondria. Pathogenic variants of CLPP have been identified in patients with Perrault syndrome type 3 (PRLTS3), a rare recessive mitochondrial disease characterized by sensorineural hearing loss, ovarian dysfunction, and neurological abnormalities. However, it remains unclear how these ClpP variants cause this disease. Here we identify three cellular substrates of ClpXP using proteomic analysis of PRLTS3 patient-derived fibroblasts, with follow up studies using induced pluripotent stem cells (iPSCs) and iPSC-derived neural progenitor cells, alongside in vitro biochemical assays. These substrates are: CHCHD2, a bi-organellar regulator of oxidative phosphorylation and mitochondrial stress responses; ALAS1, which catalyzes the rate-limiting step in heme biosynthesis; and TFAM, an essential mitochondrial transcription factor. Efficient degradation of these substrates by ClpXP requires the adaptor protein PDIP38. We propose that dysregulated cellular levels of these substrates might contribute to the etiology of PRLTS3.