Bc1-2 Family Proteins in the Ischemic Neuronal Injury

描述（由申请人提供）：中风或脑部发作引起的血管闭塞或中断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，但大量神经元死于细胞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，尽管它们如何在这一过程中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，与缺血性神经元死亡有关。两个促凋亡Bcl-2家族成员Bid和Bax可以通过触发包括细胞色素c释放在内的线粒体功能障碍来激活半胱天冬酶。在我们的初步研究中，我们发现在局灶性缺血模型中，bid缺陷小鼠对缺血性神经元死亡有明显的抗性。此外，Bid和Bax均缺乏的小鼠对缺血性损伤表现出更大的抵抗力。最后，在分子水平上，Bid和Bax可以相互作用，协同增强彼此的活性。因此，我们提出了我们的假设，即Bid和Bax都是通过诱导线粒体功能障碍和激活caspase级联而对缺血诱导的神经元凋亡性死亡的发展至关重要。此外，虽然这两种蛋白可能通过不同的机制被激活，但它们实现了将细胞外死亡刺激传递给线粒体，然后以协同方式启动执行的相同目标。我们将从以下几个方面具体检验这一假设：1)。探讨Bid和Bax对小鼠局灶性缺血模型神经元死亡的影响[2]。3)通过体外神经元损伤模型确定Bid和Baxc在神经元细胞线粒体损伤中的作用。目的探讨Bid和Bax在诱导脑分离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.