Protection from Palmitate-Induced Mitochondrial DNA Damage Prevents from Mitochondrial Oxidative Stress, Mitochondrial Dysfunction, Apoptosis, and Impaired Insulin Signaling in Rat L6 Skeletal Muscle Cells
Protection from Palmitate-Induced Mitochondrial DNA Damage Prevents from Mitochondrial Oxidative Stress, Mitochondrial Dysfunction, Apoptosis, and Impaired Insulin Signaling in Rat L6 Skeletal Muscle Cells
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DOI：
10.1210/en.2011-1442
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发表时间：
2012-01-01
期刊：
影响因子：
4.8
通讯作者：
Rachek, Lyudmila I.
中科院分区：
文献类型：
--
作者：
Yuzefovych, Larysa V.;Solodushko, Viktoriya A.;Rachek, Lyudmila I.
饱和游离脂肪酸与2型糖尿病中观察到的氧化应激、线粒体功能障碍、细胞凋亡和胰岛素抵抗的增加有关。本研究的目的是确定棕榈酸诱导的线粒体DNA（mtDNA）损伤是否导致骨骼肌细胞中氧化应激增加、线粒体功能障碍、细胞凋亡、胰岛素信号传导受损和葡萄糖摄取减少。使用腺病毒载体将DNA修复酶人8-氧代鸟嘌呤DNA糖基化酶/（脱嘌呤/脱嘧啶）裂解酶（hOGG 1）递送至L 6肌管中的线粒体。棕榈酸暴露后，我们评估了线粒体DNA损伤，线粒体功能，线粒体活性氧的产生，细胞凋亡，胰岛素信号通路和葡萄糖摄取。通过靶向线粒体的hOGG 1过表达保护线粒体DNA免受棕榈酸诱导的损伤显著减少了棕榈酸诱导的线粒体超氧化物产生，恢复了ATP水平的下降，减少了c-Jun N-末端激酶（JNK）激酶的激活，阻止了细胞进入凋亡，增加胰岛素刺激的丝氨酸-苏氨酸激酶（Akt）（Ser 473）磷酸化和胰岛素受体底物-1的酪氨酸磷酸化，从而增强葡萄糖转运蛋白4向质膜的转运，并恢复胰岛素信号传导。添加JNK的特异性抑制剂模拟了线粒体过表达hOGG 1的作用，并部分恢复了胰岛素敏感性，从而证实了L 6肌管中线粒体DNA损伤和随后的氧化应激和JNK激活在胰岛素信号传导中的增加。我们的研究结果首次报道了线粒体DNA损伤是棕榈酸诱导的线粒体功能障碍和胰岛素信号转导受损的近端原因，并提供了强有力的证据，表明将DNA修复酶靶向骨骼肌线粒体可能是胰岛素抵抗的潜在治疗方法。（内分泌学153：92-100，2012）
Saturated free fatty acids have been implicated in the increase of oxidative stress, mitochondrial dysfunction, apoptosis, and insulin resistance seen in type 2 diabetes. The purpose of this study was to determine whether palmitate-induced mitochondrial DNA (mtDNA) damage contributed to increased oxidative stress, mitochondrial dysfunction, apoptosis, impaired insulin signaling, and reduced glucose uptake in skeletal muscle cells. Adenoviral vectors were used to deliver the DNA repair enzyme human 8-oxoguanine DNA glycosylase/(apurinic/apyrimidinic) lyase (hOGG1) to mitochondria in L6 myotubes. After palmitate exposure, we evaluated mtDNA damage, mitochondrial function, production of mitochondrial reactive oxygen species, apoptosis, insulin signaling pathways, and glucose uptake. Protection of mtDNA from palmitate-induced damage by overexpression of hOGG1 targeted to mitochondria significantly diminished palmitate-induced mitochondrial superoxide production, restored the decline in ATP levels, reduced activation of c-Jun N-terminal kinase (JNK) kinase, prevented cells from entering apoptosis, increased insulin-stimulated phosphorylation of serine-threonine kinase (Akt) (Ser473) and tyrosine phosphorylation of insulin receptor substrate-1, and thereby enhanced glucose transporter 4 translocation to plasma membrane, and restored insulin signaling. Addition of a specific inhibitor of JNK mimicked the effect of mitochondrial overexpression of hOGG1 and partially restored insulin sensitivity, thus confirming the involvement of mtDNA damage and subsequent increase of oxidative stress and JNK activation in insulin signaling in L6 myotubes. Our results are the first to report that mtDNA damageis the proximal cause in palmitate-induced mitochondrial dysfunction and impaired insulin signaling and provide strong evidence that targeting DNA repair enzymes into mitochondria in skeletal muscles could be a potential therapeutic treatment for insulin resistance. (Endocrinology 153: 92-100, 2012)