Karthikeyan Gopalakrishnan, Santos Janine H, Graziewicz Maria A, Copeland William C, Isaya Grazia, Van Houten Bennett, Resnick Michael A
Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA.
Hum Mol Genet. 2003 Dec 15;12(24):3331-42. doi: 10.1093/hmg/ddg349. Epub 2003 Oct 21.
Frataxin protein controls iron availability in mitochondria and reduced levels lead to the human disease, Friedreich's ataxia (FRDA). The molecular aspects of disease progression are not well understood. We developed a highly regulatable promoter system for expressing frataxin in yeast to address the consequences of chronically reduced amounts of this protein. Shutting off the promoter resulted in changes normally associated with loss of frataxin including iron accumulation within the mitochondria and the induction of mitochondrial petite mutants. While there was considerable oxidative damage to mitochondrial proteins, the petites were likely due to accumulation of mitochondrial DNA lesions and subsequent DNA loss. Chronically reduced frataxin levels resulted in similar response patterns. Furthermore, nuclear DNA damage was detected in a rad52 mutant, deficient in double-strand break repair. We conclude that reduced frataxin levels, which is more representative of the disease state, results in considerable oxidative damage in both mitochondrial and nuclear DNA.
铁调素蛋白控制线粒体中的铁供应，其水平降低会导致人类疾病——弗里德赖希共济失调（FRDA）。疾病进展的分子机制尚未完全明确。我们开发了一种高度可调控的启动子系统，用于在酵母中表达铁调素，以研究该蛋白长期减少的后果。关闭启动子会导致通常与铁调素缺失相关的变化，包括线粒体内铁积累以及线粒体小菌落突变体的诱导。虽然线粒体蛋白存在相当程度的氧化损伤，但小菌落可能是由于线粒体DNA损伤的积累以及随后的DNA丢失所致。铁调素水平长期降低会导致类似的反应模式。此外，在缺乏双链断裂修复的rad52突变体中检测到核DNA损伤。我们得出结论，更能代表疾病状态的铁调素水平降低会导致线粒体和核DNA都出现相当程度的氧化损伤。
