Molecular Mechanisms of Apoptosis Regulation Through IP3 Receptors

项目摘要/摘要 肌醇1，4，5-三磷酸受体(IP3Rs)是细胞内主要的钙释放通道。 可兴奋的细胞。IP3R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，细胞凋亡和坏死。由于它在细胞命运决定中的不同角色，它可能是 毫不奇怪，肿瘤细胞可以通过增选和修饰IP3R介导的基因来获得选择性优势 作为这些过程基础的CA2信令网络。细胞用来逃脱编程的一种机制 细胞死亡是指增加抗细胞凋亡的bcl2蛋白的表达，包括Bcl2、Bclxl和Mcl-1。其中 BCL2蛋白在细胞中具有不同的抗细胞凋亡作用，可与IP3R结合，调节细胞内钙动态。尽管 广泛研究IP3R在细胞凋亡中的作用及bcl2-IP3R的抗凋亡作用 相互作用，IP3R门控和bcl2蛋白调节的机制了解得很少 在分子水平上。然而，很明显，BCL2-IP3R的相互作用促进了细胞的存活，以响应 细胞凋零的侮辱。BCL2和IP3R的相互作用在增强的线粒体之间对细胞的节流 通过激活依赖于钙的酶和代谢产物的生物能量学，以及通过大量的 钙离子流入线粒体，导致线粒体钙超载和外膜通透， 在细胞凋亡中的承诺步骤。在拟议的工作中，职能和结构办法将是 用来建立钙和IP3激活IP3R和抑制IP3R的机理理解 通过高浓度的钙离子。此外，通过单通道研究和BCL2-IP3R的解决方案 复杂的结构，将为bcl2蛋白调节IP3R的机制奠定基础。这项工作 将提供一个新的框架，通过它我们可以理解IP3R介导的细胞死亡，为新的 理解和设计治疗学。

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.