Ischemic preconditioning targets the respiration of synaptic mitochondria via protein kinase Cε
Ischemic preconditioning targets the respiration of synaptic mitochondria via protein kinase Cε
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DOI：
10.1523/jneurosci.5471-07.2008
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发表时间：
2008-04-16
影响因子：
5.3
通讯作者：
Perez-Pinzon, Miguel A.
中科院分区：
文献类型：
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作者：
Dave, Kunjan R.;DeFazio, R. Anthony;Perez-Pinzon, Miguel A.
在大脑中，缺血预适应(IPC)可减轻缺血后线粒体功能障碍，并提供神经保护。Epsilon蛋白激酶C(epsilon Protein Kinase C，epsilon PKC)的激活被认为是IPC的关键神经保护途径。我们验证了IPC增加大鼠海马区突触体内epsilon PKC水平的假设，从而改善了突触线粒体的呼吸。再灌流2d，即神经保护的高峰期，预适应使假手术组大鼠海马区突触小体PKC的表达水平显著升高至152%。我们检测了预适应后2d，epsilon PKC激活对海马区突触线粒体呼吸的影响。用特定的epsilon PKC活化肽Tat-psi epsilon Rack(TAT-psi epsilon-活化C激酶受体)处理后，在有底物存在的情况下，复合体I、II和IV的耗氧率分别增加到对照(单独使用TAT肽)的157、153和131%。同时，我们发现预适应动物突触体内的epsilon PKC激活导致了线粒体呼吸链蛋白磷酸化水平的改变：复合体I的18 kDa亚基的丝氨酸和酪氨酸磷酸化增加，复合体III的FES蛋白的丝氨酸磷酸化降低，环氧合酶IV(细胞色素氧化酶IV)的苏氨酸磷酸化增加，线粒体膜电位增加，H_2O_2产生减少。总之，缺血预适应促进突触体epsilon PKC水平显著升高。Epsilon PKC的激活增加了突触体的呼吸和线粒体呼吸链蛋白的磷酸化。我们认为，在缺血预适应再灌流48h后，epsilon PKC处于突触线粒体的位置，通过直接磷酸化或激活epsilon PKC信号通路对缺血作出反应。
In the brain, ischemic preconditioning (IPC) diminishes mitochondrial dysfunction after ischemia and confers neuroprotection. Activation of epsilon protein kinase C (epsilon PKC) has been proposed to be a key neuroprotective pathway during IPC. We tested the hypothesis that IPC increases the levels of epsilon PKC in synaptosomes from rat hippocampus, resulting in improved synaptic mitochondrial respiration. Preconditioning significantly increased the level of hippocampal synaptosomal epsilon PKC to 152% of sham-operated animals at 2d of reperfusion, the time of peak neuroprotection. We tested the effect of epsilon PKC activation on hippocampal synaptic mitochondrial respiration 2d after preconditioning. Treatment with the specific epsilon PKC activating peptide, tat-psi epsilon RACK (tat-psi epsilon-receptor for activated C kinase), increased the rate of oxygen consumption in the presence of substrates for complexes I, II, and IV to 157, 153, and 131% of control (tat peptide alone). In parallel, we found that epsilon PKC activation in synaptosomes from preconditioned animals resulted in altered levels of phosphorylated mitochondrial respiratory chain proteins: increased serine and tyrosine phosphorylation of 18 kDa subunit of complex I, decreased serine phosphorylation of FeS protein in complex III, increased threonine phosphorylation of COX IV (cytochrome oxidase IV), increased mitochondrial membrane potential, and decreased H2O2 production. In brief, ischemic preconditioning promoted significant increases in the level of synaptosomal epsilon PKC. Activation of epsilon PKC increased synaptosomal mitochondrial respiration and phosphorylation of mitochondrial respiratory chain proteins. We propose that, at 48 h of reperfusion after ischemic preconditioning, epsilon PKC is poised at synaptic mitochondria to respond to ischemia either by direct phosphorylation or activation of the epsilon PKC signaling pathway.