Costa Alexandre D T, Garlid Keith D, West Ian C, Lincoln Thomas M, Downey James M, Cohen Michael V, Critz Stuart D
Department of Biology, Portland State University, Portland, Ore, USA.
Circ Res. 2005 Aug 19;97(4):329-36. doi: 10.1161/01.RES.0000178451.08719.5b. Epub 2005 Jul 21.
Ischemic and pharmacological preconditioning can be triggered by an intracellular signaling pathway in which Gi-coupled surface receptors activate a cascade including phosphatidylinositol 3-kinase, endothelial nitric oxide synthase, guanylyl cyclase, and protein kinase G (PKG). Activated PKG opens mitochondrial KATP channels (mitoKATP) which increase production of reactive oxygen species. Steps between PKG and mitoKATP opening are unknown. We describe effects of adding purified PKG and cGMP on K+ transport in isolated mitochondria. Light scattering and respiration measurements indicate PKG induces opening of mitoKATP similar to KATP channel openers like diazoxide and cromakalim in heart, liver, and brain mitochondria. This effect was blocked by mitoKATP inhibitors 5-hydroxydecanoate, tetraphenylphosphonium, and glibenclamide, PKG-selective inhibitor KT5823, and protein kinase C (PKC) inhibitors chelerythrine, Ro318220, and PKC-epsilon peptide antagonist epsilonV(1-2). MitoKATP are opened by the PKC activator 12-phorbol 13-myristate acetate. We conclude PKG is the terminal cytosolic component of the trigger pathway; it transmits the cardioprotective signal from cytosol to inner mitochondrial membrane by a pathway that includes PKC-epsilon.
缺血预处理和药物预处理可由细胞内信号通路触发，其中与Gi偶联的表面受体激活一个级联反应，包括磷脂酰肌醇3激酶、内皮型一氧化氮合酶、鸟苷酸环化酶和蛋白激酶G（PKG）。激活的PKG会打开线粒体ATP敏感性钾通道（mitoKATP），从而增加活性氧的产生。PKG与mitoKATP开放之间的步骤尚不清楚。我们描述了添加纯化的PKG和环鸟苷酸（cGMP）对分离线粒体中钾离子转运的影响。光散射和呼吸测量表明，PKG诱导mitoKATP开放，类似于心脏、肝脏和脑线粒体中的ATP敏感性钾通道开放剂如二氮嗪和克罗卡林。这种效应被mitoKATP抑制剂5-羟基癸酸、四苯基鏻和格列本脲、PKG选择性抑制剂KT5823以及蛋白激酶C（PKC）抑制剂白屈菜红碱、Ro318220和PKC-ε肽拮抗剂εV(1-2)所阻断。PKC激活剂12-佛波醇13-肉豆蔻酸酯可打开mitoKATP。我们得出结论，PKG是触发通路的终端胞质成分；它通过一条包括PKC-ε的途径将心脏保护信号从胞质传递到线粒体内膜。
