Mechanism of Bax/Bak Activation During Apoptosis

细胞凋亡是一个重要的细胞死亡程序，控制正常发育和维持稳态。 细胞凋亡的异常调控导致许多疾病，如神经退行性变、自身免疫性疾病、 疾病和癌症。细胞凋亡依赖性途径是主要的细胞凋亡途径， 由Bcl-2家族蛋白调节和执行。Bcl-2家族包括五个抗凋亡成员，两个 效应蛋白Bax和巴克，以及8种促凋亡的仅BH 3蛋白。它们控制着线粒体 线粒体外膜透化（MOMP）是一个中心控制点， 到凋亡。我们的长期目标是阐明信号通路和分子机制 负责细胞凋亡，并提供积极的影响，发展更多的 有效和特异性的治疗方法，以对抗糖尿病相关疾病。虽然基因和生物化学研究 长期以来，Bax和巴克作为MOMP的两个重要效应物的作用，Bax/巴克的机制 激活，通常被认为是细胞的生死开关，已经在细胞中进行了深入的研究。 过去二十年目前的共识是，虽然所有促凋亡的BH3-only蛋白抑制抗凋亡的BH3-only蛋白。 凋亡Bcl-2蛋白，一个仅含BH 3蛋白的亚类，在细胞凋亡过程中直接参与并激活Bax和巴克。 凋亡然而，在我们的初步研究中，我们提供的遗传证据表明，这种仅含BH3的 Bax/巴克激活和凋亡不需要蛋白介导的直接激活。相反，我们的结果 提示在仅BH 3蛋白介导的抗凋亡Bcl-2蛋白的中和作用后，Bax/巴克 经历一个膜依赖性的自发激活过程。根据我们的初步研究， 提出了一个新的Bax/巴克激活模型，这将主要通过遗传学，细胞生物学， 生物化学方法。提出了以下三个目标。在目标1中，我们将研究 BH3-only蛋白和其他潜在的直接激活剂在Bax/巴克激活后的抗- 凋亡Bcl-2蛋白。在目的2中，我们将研究线粒体外膜在细胞凋亡中的作用。 Bax/巴克激活的调节。目的3：研究Bcl-2蛋白抗凋亡的机制。 介导的Bax/巴克激活的抑制。总的来说，我们提出的研究有望阐明 凋亡过程中Bax/巴克激活的机制。这一提议可能不仅会解开长期以来 这是细胞凋亡研究中的一个未解之谜，也为治疗干预提供了新的靶点。

Apoptosis is an essential cellular death program that controls proper development and maintains homeostasis. Aberrant regulation of apoptosis contributes to many diseases, such as neurodegeneration, autoimmune diseases, and cancer. The mitochondria-dependent pathway is a major apoptotic pathway, and is primarily regulated and executed by the Bcl-2 family proteins. The Bcl-2 family includes five anti-apoptotic members, two effector proteins Bax and Bak, and eight pro-apoptotic BH3-only proteins. They control the mitochondrial pathway at the step of mitochondrial outer membrane permeabilization (MOMP), a central control point leading to apoptosis. Our long term goal is to elucidate the signaling pathways and molecular mechanisms responsible for mitochondria-dependent apoptosis, and provide positive impact on the development of more potent and specific therapies against apoptosis-related diseases. While genetic and biochemical studies have long established the role of Bax and Bak as two essential effectors of MOMP, the mechanism of Bax/Bak activation, commonly considered the life-to-death switch of the cells, has been intensively investigated in the past two decades. The current consensus is that while all pro-apoptotic BH3-only proteins suppress the anti- apoptotic Bcl-2 proteins, a subset of BH3-only proteins directly engage and activate Bax and Bak during apoptosis. However, in our preliminary studies, we provide genetic evidence suggesting that such a BH3-only protein-mediated direct activation is not necessary for Bax/Bak activation and apoptosis. Instead, our results suggest that upon the BH3-only protein-mediated neutralization of the anti-apoptotic Bcl-2 proteins, Bax/Bak undergo a membrane-dependent, spontaneous activation process. Based on our preliminary studies, we propose a new model of Bax/Bak activation, which will be examined primarily by genetics, cell biology, and biochemical approaches. The following three Aims are proposed. In Aim 1, we will examine the role of the BH3-only proteins and other potential direct activators in Bax/Bak activation following the inactivation of anti- apoptotic Bcl-2 proteins. In Aim 2, we will investigate the involvement of mitochondrial outer membrane in the regulation of Bax/Bak activation. In Aim 3, we will investigate the mechanism of anti-apoptotic Bcl-2 protein- mediated suppression of the Bax/Bak activation. Overall, our proposed studies are expected to elucidate the mechanism of Bax/Bak activation during apoptosis. This proposal may not only unravel one of the long standing mysteries in apoptosis research, but also provide novel targets for therapeutic intervention.