PDF(Pubmed)
Abstract：
In the present study, we examined the mitochondrial hydrogen peroxide (mH2O2) generating capacity of α-ketoglutarate dehydrogenase (KGDH) and compared it to components of the electron transport chain using liver mitochondria isolated from male and female C57BL6N mice. We show for the first time there are some sex dimorphisms in the production of mH2O2 by electron transport chain complexes I and III when mitochondria are fueled with different substrates. However, in our investigations into these sex effects, we made the unexpected and compelling discovery that 1) KGDH serves as a major mH2O2 supplier in male and female liver mitochondria and 2) KGDH can form mH2O2 when liver mitochondria are energized with fatty acids but only when malate is used to prime the Krebs cycle. Surprisingly, 2-keto-3-methylvaleric acid (KMV), a site-specific inhibitor for KGDH, nearly abolished mH2O2 generation in both male and female liver mitochondria oxidizing palmitoyl-carnitine. KMV inhibited mH2O2 production in liver mitochondria from male and female mice oxidizing myristoyl-, octanoyl-, or butyryl-carnitine as well. S1QEL 1.1 (S1) and S3QEL 2 (S3), compounds that inhibit reactive oxygen species generation by complexes I and III, respectively, without interfering with OxPhos and respiration, had a negligible effect on the rate of mH2O2 production when pyruvate or acyl-carnitines were used as fuels. However, inclusion of KMV in reaction mixtures containing S1 and/or S3 almost abolished mH2O2 generation. Together, our findings suggest KGDH is the main mH2O2 generator in liver mitochondria, even when fatty acids are used as fuel.
摘要：
在本研究中,我们检查了α-酮戊二酸脱氢酶（KGDH）的线粒体过氧化氢（mH2O2）产生能力，并使用从雄性和雌性C57BL6N小鼠分离的肝脏线粒体将其与电子传递链（ETC）的成分进行了比较。我们首次显示，当线粒体以不同底物为燃料时，ETC复合物I和III在mH2O2的产生中存在一些性别二态。然而,在我们对这些性影响的调查中，我们意外发现:1.KGDH是男性和女性肝线粒体和2的主要mH2O2供应商。当线粒体被脂肪酸激活时，KGDH可以形成mH2O2，但只有当苹果酸被用来引发克雷布斯循环时。令人惊讶的是,2-酮-3-甲基戊酸（KMV），KGDH的位点特异性抑制剂，在氧化棕榈酰肉碱的男性和女性肝脏线粒体中几乎消除了mH2O2的产生。KMV抑制氧化肉豆蔻酰基-的雄性和雌性小鼠肝脏线粒体中mH2O2的产生，辛酰基-,或者丁酰肉碱.S1QEL1.1(S1)和S3QEL2(S3)，抑制复合物I和III产生活性氧（ROS）的化合物，分别,不干扰OxPhos，当丙酮酸或酰基肉碱用作燃料时，对mH2O2产生速率的影响可忽略不计。然而,在含有S1和/或S3的反应混合物中包含KMV几乎消除了mH2O2的产生。一起,我们的发现表明KGDH是肝脏线粒体中主要的mH2O2发生器，即使使用脂肪酸作为燃料。
