Molecular Mechanisms of Apoptosis Regulation Through IP3 Receptors

项目总结/摘要 肌醇1，4，5-三磷酸受体（IP 3Rs）是非内皮细胞主要的胞内Ca ~（2+）释放通道。 可兴奋细胞IP 3R活性驱动许多细胞过程，包括细胞分裂、迁移、线粒体 生物能量学、自噬、凋亡和坏死。由于其在细胞命运决定中的不同作用， 毫不奇怪，肿瘤细胞可以通过选择和修饰IP 3R介导的 Ca 2+信号网络是这些过程的基础。细胞用来逃避编程的一种机制 细胞死亡是为了增加抗凋亡BCL 2蛋白的表达，包括Bcl-2、Bcl-xL和Mcl-1。之间 BCL 2蛋白在细胞中的各种抗凋亡作用，BCL 2蛋白结合IP 3R并调节Ca 2+动力学。尽管 IP 3R在细胞凋亡中的作用和BCL 2-IP 3R的抗细胞凋亡作用的广泛表征 相互作用，对BCL 2蛋白的IP 3R门控和调节机制的理解很少 在分子水平上。然而，清楚的是，BCL 2-IP 3R相互作用促进细胞存活，以响应 凋亡损伤BCL 2和IP 3R之间的相互作用在增强的线粒体之间节流细胞 通过激活Ca 2+依赖性酶和代谢物的生物能量学，以及通过大的 Ca 2+流入线粒体，导致线粒体Ca 2+过载和外膜透化， 细胞凋亡中的定型步骤。在拟议的工作中，将采用功能和结构方法， 用于建立Ca 2+和IP 3激活IP 3R以及抑制IP 3R的机制理解 高浓度的Ca 2+。此外，通过单通道的研究和解决方案的BCL 2-IP 3R 复杂的结构，由BCL 2蛋白调节IP 3R的机制基础将被开发。工作 将提供一个新的框架，通过它我们可以理解IP 3R介导的细胞死亡，为新的 理解和设计治疗方法。

Project Summary/Abstract Inositol 1,4,5-trisphosphate receptors (IP3Rs) are the primary intracellular Ca2+ release channels in non- excitable cells. IP3R activity drives numerous cellular processes including cell division, migration, mitochondrial bioenergetics, autophagy, apoptosis and necrosis. Due to its diverse roles in cell fate decisions, it is perhaps unsurprising that tumor cells can gain a selective advantage by co-opting and modifying the IP3R-mediated Ca2+ signaling networks that underlie these processes. One mechanism that cells use to escape programmed cell death is to increase expression of anti-apoptotic BCL2 proteins, including Bcl-2, Bcl-xL, and Mcl-1. Among their various anti-apoptotic roles in cells, BCL2 proteins bind to IP3R and modulate Ca2+ dynamics. Despite extensive characterization of the role of IP3R in apoptosis and the anti-apoptotic effects of BCL2-IP3R interactions, mechanistic understanding of IP3R gating and modulation by BCL2 proteins is poorly understood at the molecular level. It is clear, however, that BCL2-IP3R interactions promote cell survival in response to apoptotic insult. Interactions between BCL2 and IP3R throttle the cell between enhanced mitochondrial bioenergetics through activation of Ca2+-dependent enzymes and metabolites, and cell death through large Ca2+ flux into the mitochondrial, leading to mitochondrial Ca2+ overload and outer membrane permeabilization, the commitment step in apoptosis. In the proposed work, functional and structural approaches will be employed to establish a mechanistic understanding of activation of IP3R by Ca2+ and IP3, and inhibition of IP3R by high Ca2+ concentrations. Furthermore, through single channel studies and solution of a BCL2-IP3R complex structure, a mechanistic basis for the regulation of IP3R by BCL2 proteins will be developed. The work will provide a new framework by which we can understand IP3R-mediated cell death, paving the way for new understanding and the design of therapeutics.