Neuroprotective effect of HSP27 in Cerebral Ischemia

描述（由申请人提供）：HSP27是小热休克蛋白家族的一员，热休克蛋白是一组普遍存在的应激蛋白，几乎在所有生物中表达。脑缺血后，HSP27在脑内的表达被显著诱导，实验证据表明，HSP27是一种有前景的内源性神经保护剂，可预防损伤性神经元细胞死亡。本研究旨在探讨HSP27在脑缺血模型中的神经保护作用及其潜在的分子机制。需要验证的总体假设是，HSP27的表达增强和磷酸化依赖激活通过新的抗凋亡机制保护缺血性脑损伤。我们最近创建了过表达野生型HSP27或非磷酸化HSP27突变体的转基因小鼠。通过转基因和基因转染两种方法，我们已经获得了令人兴奋的初步结果，表明HSP27在体内和体外均可保护缺血性细胞死亡，HSP27的神经保护作用依赖于磷酸化介导的蛋白质激活，HSP27可能通过直接抑制ASK1和ASK1依赖的凋亡信号通路来实现神经保护作用。本申请中提出的研究将进一步探索HSP27作为脑缺血的神经保护分子，本研究的结果可能对中风的治疗有未来的意义。提议的具体目标如下：目标1。验证转基因过表达和磷酸化依赖性激活HSP27对局灶性缺血性脑损伤的保护作用。目标2。验证HSP27对缺血性神经元损伤的神经保护作用是通过新的抗凋亡机制介导的，该机制涉及破坏ask1依赖的凋亡信号通路。目标3。验证TAT蛋白转导结构域介导的HSP27进入脑保护局灶性缺血性脑损伤的假设。提出了体内和体外模型的研究。局灶性脑缺血的体内动物模型模拟了临床缺血后脑的许多病理生理变化。体外模型将通过允许进行精确的机制研究来补充体内研究。

DESCRIPTION (provided by applicant): HSP27 is a member of the small heat shock protein family, a group of ubiquitous stress proteins that are expressed in virtually all organisms. The expression of HSP27 is markedly induced in the brain after cerebral ischemia, and experimental evidence suggests that HSP27 is a promising endogenous neuroprotectant against injury-induced neuronal cell death. The studies outlined in this proposal attempt to investigate the neuroprotective effect of HSP27 and the underlying molecular mechanism in models of cerebral ischemia. The overall hypothesis to be tested is that enhanced expression and phosphorylation- dependent activation of HSP27 protects against ischemic brain injury via novel anti-apoptotic mechanisms. We have recently created transgenic mice overexpressing either the wild-type HSP27 or a non- phosphorylatable HSP27 mutant. Using both transgenic and gene-transfection approaches, we have obtained exciting preliminary results suggesting that overexpression of HSP27 protects against ischemic cell death in both in vivo and in vitro settings, that the neuroprotective effect of HSP27 is dependent on phosphorylation-mediated activation of the protein, and that HSP27 may achieve the neuroprotective effect by directly inhibiting ASK1 and ASK1-dependent apoptosis signaling pathways. The proposed studies outlined in this application will further explore HSP27 as a neuroprotective molecule in cerebral ischemia, and results from this research may have future therapeutic implications for stroke. The following specific objectives are proposed: Aim 1. Test the hypothesis that transgenic overexpression and phosphorylation-dependent activation of HSP27 protects against focal ischemic brain injury. Aim 2. Test the hypothesis that the neuroprotective effect of HSP27 against ischemic neuronal injury is mediated via novel anti-apoptotic mechanisms involving the disruption of ASK1-dependent apoptosis signaling pathways. Aim 3. Test the hypothesis that TAT protein transduction domain-mediated delivery of HSP27 into the brain protects against focal ischemic brain injury. Studies in both in vivo and in vitro models are proposed. The in vivo animal model of focal cerebral ischemia mimics many aspects of pathophysiological changes in the brain after clinical ischemia. The in vitro models will complement the in vivo studies by allowing for precise mechanistic studies to be performed.