Bc1-2 Family Proteins in the Ischemic Neuronal Injury

描述（由申请人提供）：中风或脑发作导致的血管闭塞或破裂可导致脑缺血和缺氧，从而导致严重的神经元损伤。虽然受损的神经元通常死于坏死，但大量的神经元死于凋亡或程序性细胞死亡。对细胞凋亡基本机制的研究已经确定，一组半胱氨酸蛋白酶，即，半胱天冬酶负责执行死亡程序。半胱天冬酶积极参与缺血/缺氧诱导的神经元细胞死亡的发病机制，尽管它们在这个过程中如何被激活在很大程度上是难以捉摸的。Bcl-2家族蛋白是重要的细胞凋亡调节因子，并与缺血性神经元死亡有关。Bcl-2家族的两个促凋亡成员Bid和Bax可以通过触发线粒体功能障碍（包括细胞色素c释放）来激活半胱天冬酶。在我们的初步研究中，我们发现bid缺陷小鼠在局灶性缺血模型中对缺血性神经元死亡具有显著的抵抗力。此外，Bid和Bax缺陷的小鼠表现出对缺血性损伤的更大抵抗力。最后，在分子水平上，Bid和Bax可以相互作用并协同增强彼此的活性。因此，我们制定了我们的假设，投标和Bax是通过诱导线粒体功能障碍和激活caspase级联缺血诱导的神经元凋亡性死亡的发展至关重要。此外，虽然这两种蛋白质可能被不同的机制激活，但它们仍然实现了将细胞外死亡刺激传递到线粒体的相同目标，然后以协作方式启动执行。我们将具体从以下几个方面来检验这一假设：1）。在小鼠局灶性缺血模型中研究Bid和Bax对神经元死亡的贡献，2）。用体外神经元损伤模型来确定Bid和Bpoc在神经元细胞中线粒体损伤中的作用，以及3）。研究Bid和Bax在诱导脑线粒体功能障碍中的分子相互作用。

DESCRIPTION (provided by applicant): Vascular occlusion or disruption resulted from stroke, or brain attack, can lead to brain ischemia and hypoxia that can result in serious neuronal injury. While damaged neurons often die from necrosis, significant amount of neurons die from apoptosis, or programmed cell death. Studies on the basic mechanisms of apoptosis have established that a group of cysteine proteases, i.e., caspases, are responsible for the execution of the death program. Caspases actively participate in the pathogenesis of ischemia/hypoxia-induced neuronal cell death, although how they are activated in this process is largely elusive. Bcl-2 family proteins are important apoptosis regulators and have been implicated in ischemic neuronal death. Two pro-apoptosis Bcl-2 family members, Bid and Bax, can activate caspases by triggering mitochondrial dysfunction including cytochrome c release. In our preliminary studies, we found that bid-deficient mice were significantly resistant to ischemic neuronal death in a focal ischemia model. In addition, mice deficient in both Bid and Bax demonstrated an even bigger resistance to the ischemic injury. Finally, at the molecular level, Bid and Bax can interact with each other and synergistically enhance each other's activity. We have thus formulated our hypothesis that both Bid and Bax are critical to the development of ischemia-induced neuronal apoptotic death by inducing mitochondrial dysfunction and activating the caspase cascade. Furthermore, while the two proteins may be activated by different mechanisms, they nevertheless accomplish the same goal of transmitting extracellular death stimuli to mitochondria and then initiate the execution in a collaborative fashion. We will test this hypothesis specifically from the following aspects: 1). To investigate the contribution of Bid and Bax to neuronal death in a murine focal ischemia model, 2). To define the role of Bid and Baxc in mitochondrial damage in neuronal cells with an in vitro neuronal injury model, and 3). To characterize the molecular interactions of Bid and Bax in inducing dysfunction of mitochondria isolated from the brain.