Role of prohibitin in ischemic brain injury

 描述（由申请人提供）：缺血性卒中仍然是最普遍和最具破坏性的神经系统疾病之一，其治疗选择有限。因此，迫切需要新的治疗方法。脑缺血在组织梗死的早期阶段引起严重的且通常不可逆的线粒体损伤。反过来，受损的线粒体通过产生自由基和促进细胞死亡进一步加剧脑损伤。对缺血性脑中线粒体功能如何受损的机制理解可能会揭示保护线粒体的新方法，并导致神经保护新策略的发展。我们发现缺血预处理可上调线粒体蛋白抑制素（prohibitin，PHB）的表达，并证明基因转移的PHB表达可保护体外培养的皮层神经元免受氧糖剥夺的损伤，保护海马CA 1区神经元免受短暂前脑缺血所致的迟发性变性的损伤。这些研究清楚地表明，一个强大的神经保护潜力的聚羟基丁酸酯，但有关的神经保护机制，特别是那些特别归因于线粒体，需要阐明。为此，我们开发了条件性的PHB转基因（PHB-Tg）小鼠，在神经元或星形胶质细胞中选择性地表达PHB。使用这些小鼠，我们建议测试的假设，即聚羟基丁酸，通过调节关键的线粒体功能，调节线粒体对缺血的易感性，并保护缺血性脑损伤。特别是，我们将使用一个局灶性脑缺血模型产生的大脑中动脉（MCA）的短暂闭塞，以调查是否条件神经元或星形胶质细胞表达的聚羟基丁酸改善缺血性脑损伤。此外，我们将研究生物能量机制的线粒体保护的聚羟基丁酸，其在保护线粒体网络的完整性，通过调节线粒体融合和分裂和嵴结构缺血神经元的作用。因此，本提案的研究结果将促进我们对PHB如何调节线粒体结构，功能和动力学的理解，并将为基于调节PHB表达的缺血性损伤提供新的治疗靶点。这些发现还将促进我们对通过调节线粒体动力学来控制神经元存活和死亡的基本过程的理解，并有可能为与线粒体功能障碍相关的其他神经系统疾病确定线粒体靶向治疗策略。

 DESCRIPTION (provided by applicant): Ischemic stroke remains one of the most prevalent and devastating neurological diseases for which limited treatment options are available. Therefore, new therapeutic approaches are sorely needed. Brain ischemia causes severe and often irreversible mitochondrial damage in the early phase of tissue infarction. In turn, damaged mitochondria further exacerbate brain injury by producing free radicals and promoting cell death. A mechanistic understanding of how mitochondrial function is impaired in the ischemic brain may unveil new approaches to protect mitochondria and lead to the development of new strategies for neuroprotection. We have discovered that the mitochondrial protein prohibitin (PHB) is upregulated by ischemic preconditioning and demonstrated that PHB expression by gene transfer protected cultured cortical neurons from oxygen glucose deprivation and hippocampal CA1 neurons from the delayed degeneration produced by transient forebrain ischemia in vivo. These studies clearly suggested a strong neuroprotective potential of PHB but mechanisms pertaining to the neuroprotection, especially those attributed specifically to mitochondria, need to be elucidated. For this purpose, we have developed conditional PHB transgenic (PHB-Tg) mice that express PHB selectively in neurons or astrocytes. Using these mice we propose to test the hypothesis that PHB, by regulating critical mitochondrial functions, modulates the mitochondria's susceptibility to ischemia and protects the ischemic brain from injury. In particular, we will use a model of focal cerebral ischemia produced by transient occlusion of the middle cerebral artery (MCA) to investigate whether conditional neuronal or astrocytic expression of PHB ameliorates ischemic brain injury. Furthermore, we will examine the bioenergetic mechanisms underlying mitochondrial protection by PHB, and its role in preserving mitochondrial network integrity by regulating mitochondrial fusion and fission and cristae structure in ischemic neurons. The findings of the research from the present proposal, therefore, will advance our understanding of how PHB modulates mitochondrial structure, function and dynamics, and will provide new therapeutic targets for ischemic injury based on modulating PHB expression. The findings will also advance our understanding of the fundamental processes governing neuronal survival and death through regulation of mitochondrial dynamics, and have the potential of identifying mitochondria targeted treatment strategies for other neurological diseases linked to mitochondrial dysfunction.