Fbw7 as a therapeutic target for treating ischemic brain injury

 描述(申请人提供)：缺血性中风是由于大脑动脉供血中断所致。中断可以是永久性的，也可以是暂时的。由于大脑对氧气和葡萄糖的需求很高且持续不变，血流中断会引发极端的应激反应，最终导致神经元死亡。此外，缺血后血供的恢复会引起严重的炎症反应，导致额外的神经元死亡(再灌流损伤)。在美国和欧洲，缺血性中风是主要的死亡原因之一，幸存者面临着包括永久性残疾在内的令人衰弱的后果，因此人们寻求可能预防或减少与缺血相关的神经元死亡的治疗方法。由于许多与缺血相关的神经元死亡和所有与再灌注相关的死亡都发生在最初的缺血事件发生后的几个小时和几天内，中风后的治疗干预可能是非常有益的。我们和其他人已经证明了含有BH结构域的生存因子Mcl-1对于神经元的生存至关重要，特别是在应激条件下。我们还证明了泛素连接酶SCFFbw7以Mcl-1为靶标，用于泛素介导的神经元蛋白分解。因此，RNAi介导的这种连接酶底物结合接头Fbw7的沉默增加了原代神经元培养中Mcl-1的稳定水平，并保护它们免受应激相关的凋亡。因此，我们开始了一个项目，以确定SCFFbw7的小分子抑制剂，以便开发对导致神经元凋亡的病理条件的治疗干预措施。尽管缺血性脑损伤引起的细胞死亡不是 凋亡性神经元死亡被认为是一个重要的因素，被认为仅仅是由于细胞凋亡。到目前为止，我们已经确定了一些小分子抑制剂，它们可以阻断EC50在低到中等皮摩尔范围内的原代培养神经元的应激介导的细胞凋亡。这些应激源包括缺氧、OGD和炎性细胞因子的治疗。一种化合物(20aS20)在小鼠体内的初步药代动力学分析表明，它在体内是稳定的，并表现出良好的中枢神经系统透过性。因此，我们计划使用这种化合物来确定靶向SCFFbw7在小鼠缺血性脑损伤模型中是否具有治疗效果。然后，展示疗效将证明以抑制SCFFbw7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.