From the Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan 48201.
From the Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan 48201
J Biol Chem. 2018 Apr 27;293(17):6517-6529. doi: 10.1074/jbc.RA117.001073. Epub 2018 Mar 14.
Coiled-coil-helix-coiled-coil-helix domain-containing 10 (CHCHD10) and CHCHD2 (MNRR1) are homologous proteins with 58% sequence identity and belong to the twin CXC family of proteins that mediate cellular stress responses. Despite the identification of several neurodegeneration-associated mutations in the gene, few studies have assessed its physiological role. Here, we investigated CHCHD10's function as a regulator of oxidative phosphorylation in the mitochondria and the nucleus. We show that CHCHD10 copurifies with cytochrome oxidase (COX) and up-regulates COX activity by serving as a scaffolding protein required for MNRR1 phosphorylation, mediated by ARG (ABL proto-oncogene 2, nonreceptor tyrosine kinase (ABL2)). The gene was maximally transcribed in cultured cells at 8% oxygen, unlike , which was maximally expressed at 4%, suggesting a fine-tuned oxygen-sensing system that adapts to the varying oxygen concentrations in the human body under physiological conditions. We show that nuclear CHCHD10 protein down-regulates the expression of genes harboring the oxygen-responsive element (ORE) in their promoters by interacting with and augmenting the activity of the largely uncharacterized transcriptional repressor CXXC finger protein 5 (CXXC5). We further show that two genetic CHCHD10 disease variants, G66V and P80L, in the mitochondria exhibit faulty interactions with MNRR1 and COX, reducing respiration and increasing reactive oxygen species (ROS), and in the nucleus abrogating transcriptional repression of ORE-containing genes. Our results reveal that CHCHD10 positively regulates mitochondrial respiration and contributes to transcriptional repression of ORE-containing genes in the nucleus, and that genetic CHCHD10 variants are impaired in these activities.
卷曲螺旋-双亮氨酸重复-卷曲螺旋-双亮氨酸重复结构域蛋白 10（CHCHD10）和 CHCHD2（MNRR1）是具有 58%序列同一性的同源蛋白，属于双 CXC 蛋白家族，可介导细胞应激反应。尽管在 基因中鉴定出了几种与神经退行性变相关的突变，但很少有研究评估其生理作用。在这里，我们研究了 CHCHD10 作为线粒体和核中氧化磷酸化调节因子的功能。我们表明，CHCHD10 与细胞色素 c 氧化酶（COX）共纯化，并通过充当 MNRR1 磷酸化所需的支架蛋白来上调 COX 活性，这种磷酸化由 ARG（ABL 原癌基因 2，非受体酪氨酸激酶（ABL2））介导。与 基因不同， 基因在培养细胞中在 8%的氧气下最大转录，而在 4%的氧气下最大表达，这表明存在一个精细的氧感应系统，可适应人体在生理条件下的不同氧气浓度。我们表明，核 CHCHD10 蛋白通过与在其启动子中含有氧反应元件（ORE）的基因相互作用，并增强尚未充分表征的转录抑制因子CXXC 手指蛋白 5（CXXC5）的活性，从而下调这些基因的表达。我们进一步表明，线粒体中两个遗传 CHCHD10 疾病变体，G66V 和 P80L，与 MNRR1 和 COX 的相互作用有缺陷，降低呼吸作用并增加活性氧（ROS），而在核中，它们会阻止 ORE 基因的转录抑制。我们的结果表明，CHCHD10 正向调节线粒体呼吸作用，并有助于核中 ORE 基因的转录抑制，而遗传 CHCHD10 变体在这些活性中受损。
