εPKC phosphorylates the mitochondrial K+ATP channel during induction of ischemic preconditioning in the rat hippocampus
εPKC phosphorylates the mitochondrial K+ATP channel during induction of ischemic preconditioning in the rat hippocampus
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DOI：
10.1016/j.brainres.2007.09.073
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发表时间：
2007-12-12
期刊：
影响因子：
2.9
通讯作者：
Perez-Pinzon, Miguel A.
中科院分区：
文献类型：
--
作者：
Raval, Ami P.;Dave, Kunjan R.;Perez-Pinzon, Miguel A.
缺血预处理（IPC）对脑缺血的神经保护作用需要脑蛋白激酶C（PKC）的转位。我们实验室的一个主要目标是确定ePKC提供保护的细胞靶点。我们验证了IPC后PKC靶向线粒体K-ATP（+）通道（mtK（ATP）（+））的假设。我们的研究结果表明，IPC后大鼠海马线粒体中的PKC的快速易位。由于在其他组织中，PKC靶向mtK（ATP）（+）通道，但其在脑线粒体中的存在是有争议的，我们确定了从大鼠海马分离的线粒体中K-ATP（+）通道特异性亚基（Kir6.1和Kir6.2）的存在。接下来，我们确定mtK（ATP）（+）通道是否在IPC诱导中起作用。在海马器官型脑片培养中，通过氧-糖剥夺诱导IPC和致死性缺血。使用碘化丙啶染色定量CA 1区域中的后续细胞死亡。在致死性缺血前48 h给予K-ATP（+）通道开放剂二氮嗪或吡那地尔可保护海马CA 1区神经元，模拟IPC或PKC激动剂诱导的预处理诱导的神经保护作用。用5-羟基癸酸阻断mtK（ATP）（+）通道，可阻断IPC或PKC预处理的神经保护作用。缺血性预处理和PKC激动剂介导的预处理均导致mtK（ATP）（+）通道亚基Kir6.2磷酸化。IPC后，选择性抑制PKC活化阻止了Kir6.2磷酸化，这与Kir6.2作为PKC或其下游效应物的磷酸化靶点一致。我们的结果支持了以下假设：脑内mtK（ATP）（+）通道是IPC的重要靶点，也是PKC启动的信号转导途径。(c)2007 Elsevier B. V.保留所有权利。
Neuroprotection against cerebral ischemia conferred by ischemic preconditioning (IPC) requires translocation of epsilon protein kinase C (epsilon PKC). A major goal in our laboratory is to define the cellular targets by which ePKC confers protection. We tested the hypothesis that epsilon PKC targets the mitochondrial K-ATP(+) channel (mtK(ATP)(+)) after IPC. Our results demonstrated a rapid translocation of epsilon PKC to rat hippocampal mitochondria after IPC. Because in other tissues epsilon PKC targets mtK(ATP)(+) channels, but its presence in brain mitochondria is controversial, we determined the presence of the K-ATP(+) channel-specific subunits (Kir6.1 and Kir6.2) in mitochondria isolated from rat hippocampus. Next, we determined whether mtK(ATP)(+) channels play a role in the IPC induction. In hippocampal organotypic slice cultures, IPC and lethal ischemia were induced by oxygen-glucose deprivation. Subsequent cell death in the CA1 region was quantified using propidium iodide staining. Treatment with the K-ATP(+) channel openers diazoxide or pinacidil 48 h prior to lethal ischemia protected hippocampal CA1 neurons, mimicking the induction of neuroprotection conferred by either IPC or epsilon PKC agonist-induced preconditioning. Blockade of mtK(ATP)(+) channels using 5-hydroxydecanoic acid abolished the neuroprotection due to either IPC or epsilon PKC preconditioning. Both ischemic and epsilon PKC agonist-mediated preconditioning resulted in phosphorylation of the mtK(ATP)(+) channel subunit Kir6.2. After IPC, selective inhibition of epsilon PKC activation prevented Kir6.2 phosphorylation, consistent with Kir6.2 as a phosphorylation target of epsilon PKC or its downstream effectors. Our results support the hypothesis that the brain mtK(ATP)(+) channel is an important target of IPC and the signal transduction pathways initiated by epsilon PKC. (c) 2007 Elsevier B.V. All rights reserved.