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参与肿瘤发生和内在癌症治疗抵抗。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与肌醇1,4,5-三磷酸受体（IP3R）相互作用，从而抑制ip3诱导的钙升高，IP3R是内质网（ER）上的一个ip3门控钙通道。在目前的资助期内，我们使用FRET在细胞中证明了这种相互作用，并绘制了Bcl-2和IP3R上的相互作用位点。基于这些信息，我们开发了Bcl-2-IP3R相互作用的肽抑制剂肽2。当这种肽被传递到细胞中时，逆转了Bcl-2对促凋亡钙信号的抑制，并引发延长的钙振荡，从而升高促凋亡蛋白Bim。本研究通过研究Bcl-2-IP3R相互作用调节IP3R通道活性从而抑制IP3依赖性钙升高的基本机制来继续这项工作。此外，本研究还探讨了肽2介导的Bcl-2-IP3R相互作用抑制触发钙振荡并增加Bim水平的机制。最后，本提案探讨了靶向Bcl-2- ip3r相互作用的概念，以治疗Bcl-2过表达的癌症，包括慢性淋巴细胞白血病，与其他治疗药物协同作用。

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.