Bcl-2 function on the endoplasmic reticulum

描述（由申请人提供）：Bcl-2蛋白通过抑制细胞凋亡促进肿瘤发生和内在癌症治疗抗性。该基金支持的研究正在调查Bcl-2作用机制的一个特定方面，即抑制促进细胞凋亡的钙信号。我们发现Bcl-2与内质网（ER）上的1，4，5-三磷酸肌醇受体（IP 3R）（IP 3门控钙通道）相互作用，从而抑制IP 3诱导的钙升高。在当前的资助期内，我们使用FRET来证明细胞中的这种相互作用，并绘制了Bcl-2和IP 3R上的相互作用位点。基于此信息，我们开发了Bcl-2-IP 3R相互作用的肽抑制剂，肽2。这种肽，当被递送到细胞中时，逆转Bcl-2对促凋亡钙信号的抑制，并触发延长的钙振荡，从而升高促凋亡蛋白Bim。本提案通过研究Bcl-2-IP 3R相互作用调节IP 3R通道活性从而抑制IP 3依赖性钙升高的基本机制来继续这项工作。此外，该提议研究了肽2介导的Bcl-2-IP 3R相互作用的抑制触发钙振荡并增加Bim水平的机制。最后，该提案探索了靶向Bcl-2-IP 3R相互作用的概念，用于与其他治疗剂协同治疗Bcl-2过表达的癌症，包括慢性淋巴细胞白血病。 公共卫生相关性：Bcl-2是一种非常重要的蛋白质，有助于癌症。它的功能是抑制细胞的死亡。因此，当癌细胞含有过多的这种蛋白质时，它们不会死亡。因此，癌细胞积聚并对旨在诱导细胞死亡的治疗具有抗性。这项研究旨在更好地了解Bcl-2如何抑制细胞死亡。目的是了解Bcl-2如何与癌细胞内传导钙离子的通道相互作用并调节这些通道。这些离子在介导细胞死亡中很重要。我们的研究正在调查Bcl-2关闭这些通道从而阻止钙离子诱导细胞死亡的假设。通过了解这一过程，我们可能能够开发新的癌症治疗方法，克服Bcl-2的细胞死亡抑制功能。

DESCRIPTION (provided by applicant): The Bcl-2 protein contributes to both oncogenesis and intrinsic cancer treatment resistance by inhibiting apoptosis. Research supported by this grant is investigating one particular aspect of Bcl-2's mechanism of action, the inhibition of calcium signals that promote apoptosis. We discovered that Bcl-2 interacts with the inositol 1,4,5-trisphosphate receptor (IP3R), an IP3-gated calcium channel on the endoplasmic reticulum (ER), thus inhibiting IP3-induced calcium elevation. In the current funding period we used FRET to demonstrate this interaction in cells and mapped the interaction sites on both Bcl-2 and the IP3R. Based on this information we developed a peptide inhibitor of Bcl-2-IP3R interaction, Peptide 2. This peptide, when delivered into cells, reverses the inhibition of pro-apoptotic calcium signals by Bcl-2 and triggers prolonged calcium oscillations that elevate the pro-apoptotic protein Bim. The present proposal continues this work by investigating the fundamental mechanism by which Bcl-2-IP3R interaction regulates IP3R channel activity and thus inhibits IP3- dependent calcium elevation. Also, this proposal investigates the mechanism by which Peptide 2-mediated inhibition of Bcl-2-IP3R interaction triggers calcium oscillations and increases Bim levels. Finally, this proposal explores the concept of targeting Bcl-2-IP3R interaction for treatment of Bcl-2 over-expressing cancers, including chronic lymphocytic leukemia, in synergy with other therapeutic agents. PUBLIC HEALTH RELEVANCE: Bcl-2 is a very important protein that contributes to cancer. It functions to inhibit the death of cells. Therefore, when cancer cells have too much of this protein they fail to die. Thus, the cancer cells accumulate and are resistant to treatments designed to induce cell death. This proposal is for research to better understand how Bcl-2 inhibits cell death. The goal is to understand how Bcl-2 interacts with and regulates channels that conduct calcium ions within cancer cells. These ions are important in mediating cell death. Our research is investigating the hypothesis that Bcl-2 closes these channels and thus prevents the calcium ion from inducing cell death. By understanding this process we may be able to develop new treatments for cancer that overcome the cell death inhibiting function of Bcl-2.