Fbw7 as a therapeutic target for treating ischemic brain injury

 描述（由申请人提供）：缺血性卒中是由脑动脉供血中断引起的。中断可以是永久的或暂时的。由于大脑对氧气和葡萄糖的需求很高且持续不断，血流中断会引起极端的应激反应，最终导致神经元死亡。此外，缺血后血液供应的恢复诱导了严重的炎症反应，导致额外的神经元死亡（再灌注损伤）。由于缺血性中风是美国和欧洲的主要死亡原因之一，并且幸存者面临着使人衰弱的后果，包括永久性残疾，因此已经寻求可能预防或减少缺血相关神经元死亡的疗法。由于大部分缺血相关的神经元死亡和所有再灌注相关的死亡发生在初始缺血事件后的数小时和数天内，因此中风后的治疗干预具有高度有益的潜力。我们和其他人已经证明，BH结构域的生存因子，Mcl-1，是神经元的生存，特别是在应激条件下的关键。我们还证明了泛素连接酶SCFFbw 7靶向Mcl-1，用于神经元中泛素介导的蛋白水解。因此，RNAi介导的这种连接酶的底物结合衔接子Fbw 7的沉默增加了原代神经元培养物中Mcl-1的稳态水平，并保护它们免受应激相关的凋亡。因此，我们已经开始了一项计划，以确定SCFFbw 7的小分子抑制剂，以开发治疗性干预导致神经元凋亡的病理条件。虽然由于缺血性脑损伤引起的细胞死亡不是 认为仅仅是由于细胞凋亡，细胞凋亡性神经元死亡被认为是一个重要因素。到目前为止，我们已经确定了一些小分子抑制剂，阻断应激介导的细胞凋亡的原代培养的神经元与EC 50在低至中等皮摩尔范围。这些应激源包括缺氧、OGD和炎性细胞因子治疗。一种化合物（20 aS 20）在小鼠中的初步药代动力学分析表明，它在体内是稳定的，并显示出良好的CNS清除率。因此，我们计划使用这种化合物来确定靶向SCFFbw 7是否在缺血性脑损伤的小鼠模型中具有治疗效果。证明治疗功效将证明以抑制SCFFbw 7为中心的药物发现计划是合理的。

 DESCRIPTION (provided by applicant): Ischemic stroke results from interruption of brain arterial blood supply. The interruption can be permanent or transient. Since the requirements for oxygen and glucose in the brain are high and constant, interruption of blood flow induces extreme stress responses, leading ultimately to neuronal death. In addition, restoration of blood supply subsequent to ischemia induces a profound inflammatory response causing additional neuronal death (reperfusion injury). As ischemic stroke is one of the leading causes of death in both the United States and Europe, and survivors are faced with debilitating consequences, including permanent disability, therapies that might prevent or reduce ischemia-related neuronal death have been sought. Since much of the ischemia-related neuronal death and all of the reperfusion-related death occurs over the course of hours and days following the initial ischemic event, therapeutic intervention subsequent to a stroke has the potential to be highly beneficial. We and others have demonstrated that BH domain-containing survival factor, Mcl-1, is critical for neuronal survival, particularly under conditions of stress. We have also demonstrated that a ubiquitin ligase, SCFFbw7 targets Mcl-1 for ubiquitin-mediated proteolysis in neurons. Accordingly, RNAi- mediated silencing of the substrate-binding adaptor of this ligase, Fbw7, increases steady state levels of Mcl-1 in primary neuronal cultures and protects them from stress-associated apoptosis. We have therefore embarked on a program to identify small molecule inhibitors of SCFFbw7 in order to develop therapeutic interventions for pathological conditions resulting in neuronal apoptosis. Although cell death due to ischemic brain injury is not considered to be due solely to apoptosis, apoptotic neuronal death is thought to be a significant factor. To date we have identified a number of small molecule inhibitors that block stress-mediated apoptosis in primary cultured neurons with EC50s in the low- to mid-picomolar range. These stressors include hypoxia, OGD, and treatment with inflammatory cytokines. Preliminary pharmacokinetic analysis in the mouse of one compound (20aS20) indicates that it is stable in vivo and shows good CNS penetrance. Therefore, we plan to use this compound to determine if targeting SCFFbw7 has therapeutic efficacy in mouse models of ischemic brain injury. Demonstrating therapeutic efficacy would then justify a drug discovery program centered on inhibition of SCFFbw7.