Dhar Sanjit K, Scott Timothy, Wang Chi, Fan Teresa W M, St Clair Daret K
Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, 40536-0509, USA.
Markey Cancer Center, University of Kentucky, Lexington, KY, 40536-0509, USA.
Free Radic Biol Med. 2022 Feb 1;179:181-189. doi: 10.1016/j.freeradbiomed.2021.12.309. Epub 2021 Dec 28.
Mitochondria are central to the metabolic circuitry that generates superoxide radicals/anions (O) as a by-product of oxygen metabolism. By regulating superoxide levels, manganese superoxide dismutase plays important roles in numerous biochemical and molecular events essential for the survival of aerobic life. In this study, we used MitoParaquat (mPQ) to generate mitochondria-specific O and stable isotope-resolved metabolomics tracing in primary human epidermal keratinocytes to investigate how O generated in mitochondria regulates gene expression. The results reveal that isocitrate is blocked from conversion to α-ketoglutarate and that acetyl-coenzyme A (CoA) accumulates, which is consistent with a reduction in oxygen consumption rate and inactivation of isocitrate dehydrogenase (IDH) activity. Since acetyl-CoA is linked to histone acetylation and gene regulation, we determined the effect of mPQ on histone acetylation. The results demonstrate an increase in histone H3 acetylation at lysines 9 and 14. Suppression of IDH increased histone acetylation, providing a direct link between metabolism and epigenetic alterations. The activity of histone acetyltransferase p300 increased after mPQ treatment, which is consistent with histone acetylation. Importantly, mPQ selectively increased the nuclear levels and activity of the oxidative stress-sensitive nuclear factor erythroid 2-related factor 2. Together, the results establish a new paradigm that recognizes O as an initiator of metabolic reprogramming that activates epigenetic regulation of gene transcription in response to mitochondrial dysfunction.
线粒体是代谢回路的核心，该代谢回路会产生超氧自由基/阴离子（O）作为氧代谢的副产物。通过调节超氧水平，锰超氧化物歧化酶在需氧生命生存所必需的众多生化和分子事件中发挥重要作用。在本研究中，我们使用线粒体百草枯（mPQ）在原代人表皮角质形成细胞中产生线粒体特异性O并进行稳定同位素分辨代谢组学追踪，以研究线粒体中产生的O如何调节基因表达。结果显示，异柠檬酸转化为α-酮戊二酸的过程受阻，乙酰辅酶A（CoA）积累，这与氧消耗率降低和异柠檬酸脱氢酶（IDH）活性失活一致。由于乙酰辅酶A与组蛋白乙酰化和基因调控相关，我们确定了mPQ对组蛋白乙酰化的影响。结果表明，赖氨酸9和14处的组蛋白H3乙酰化增加。抑制IDH可增加组蛋白乙酰化，这在代谢与表观遗传改变之间建立了直接联系。mPQ处理后，组蛋白乙酰转移酶p300的活性增加，这与组蛋白乙酰化一致。重要的是，mPQ选择性地增加了氧化应激敏感核因子红细胞2相关因子2的核水平和活性。总之，这些结果建立了一种新的模式，即认识到O是代谢重编程的启动因子，它可响应线粒体功能障碍激活基因转录的表观遗传调控。
