Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, Salzburg, Austria.
Biochem Biophys Res Commun. 2012 Jan 20;417(3):1052-7. doi: 10.1016/j.bbrc.2011.12.093. Epub 2011 Dec 26.
Mitochondrial DNA (mtDNA) depletion syndromes are generally associated with reduced activities of oxidative phosphorylation (OXPHOS) enzymes that contain subunits encoded by mtDNA. Conversely, entirely nuclear encoded mitochondrial enzymes in these syndromes, such as the tricarboxylic acid cycle enzyme citrate synthase (CS) and OXPHOS complex II, usually exhibit normal or compensatory enhanced activities. Here we report that a human cell line devoid of mtDNA (HEK293 ρ(0) cells) has diminished activities of both complex II and CS. This finding indicates the existence of a feedback mechanism in ρ(0) cells that downregulates the expression of entirely nuclear encoded components of mitochondrial energy metabolism.
线粒体 DNA（mtDNA）耗竭综合征通常与氧化磷酸化（OXPHOS）酶的活性降低有关，这些酶包含由 mtDNA 编码的亚基。相反，在这些综合征中完全由核编码的线粒体酶，如三羧酸循环酶柠檬酸合酶（CS）和 OXPHOS 复合物 II，通常表现出正常或代偿性增强的活性。在这里，我们报告说，缺乏 mtDNA 的人细胞系（HEK293 ρ(0)细胞）中复合物 II 和 CS 的活性都降低了。这一发现表明 ρ(0)细胞中存在一种反馈机制，下调线粒体能量代谢的完全核编码成分的表达。
