Neuroprotective effect of HSP27 in Cerebral Ischemia

描述（由申请人提供）：HSP 27是小热休克蛋白家族的成员，小热休克蛋白家族是一组普遍存在的应激蛋白，几乎在所有生物体中表达。脑缺血后脑组织中HSP 27的表达被显著诱导，实验证据表明HSP 27是一种有前途的内源性神经保护剂，可对抗损伤诱导的神经元细胞死亡。本研究拟探讨热休克蛋白27在脑缺血模型中的神经保护作用及其分子机制。待测试的总体假设是HSP 27的增强表达和磷酸化依赖性活化通过新的抗凋亡机制保护免于缺血性脑损伤。我们最近创建了过表达野生型HSP 27或非磷酸化HSP 27突变体的转基因小鼠。使用转基因和基因转染方法，我们已经获得了令人兴奋的初步结果，表明HSP 27的过表达在体内和体外环境中都能防止缺血性细胞死亡，HSP 27的神经保护作用依赖于磷酸化介导的蛋白激活，HSP27可能通过直接抑制ASK1及其依赖的凋亡信号通路发挥神经保护作用。本申请中概述的拟议研究将进一步探索HSP 27作为脑缺血中的神经保护分子，这项研究的结果可能对中风具有未来的治疗意义。提出了以下具体目标：目标1。验证HSP27的转基因过表达和磷酸化依赖性激活可保护局灶性缺血性脑损伤的假设。目标二。检验HSP 27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假设，该机制涉及ASK 1依赖性凋亡信号通路的破坏。目标3：测试达特蛋白转导结构域介导的HSP 27递送到脑中保护免于局灶性缺血性脑损伤的假设。提出了在体内和体外模型中的研究。局灶性脑缺血的体内动物模型模拟了临床缺血后脑中病理生理变化的许多方面。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.