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.