蛋白酶体去磷酸化修饰在肿瘤生成中的调控机制研究

Ubiquitin-proteasome system is the primary way by which proteins in cells degrade, and it plays a significant role in all sorts of cellular physiological processes, such as cell cycle, apoptosis, and DNA repair. On the other hand, proteasomal dysregulation is closely related to the pathogenesis of multiple diseases, particularly the tumor. It is also served as the target for kinds of antitumor medicine, yet the mechanism remains unclear. The applicant has found that Rpn1, a subunit of proteasome had direct interactions with phosphatase UBLCP1, which impaired the assembly and activity of proteasome. Moreover, UBLCP1 in ovarian carcinoma cells significantly suppressed the survival of tumor cells. During this study, the applicant will use combinational methods of biochemistry, molecular and cellular biology, and tumor biology, seeking to identify the exact subunit of proteasome that UBLCP1 has direct effect on and the underlying mechanism it works on proteasomal regulation and cancer cell behaviors. In detail, this project aims at investigating the precise mechanism of the regulatory effects of UBLCP1 dephosphorylation on the assembly and activity of proteasome and the stability of the downstream substrates, and, how dephosphorylated proteasome affects the survival and proliferation of the tumor cells, and the DNA repair process of tumor cells. We expect to unveil the regulatory role of proteasome dephosphorylation in tumor cells and provide novel insights on UBLCP1 as a potential target for cancer therapy.

泛素-蛋白酶体系统是细胞内蛋白质降解的主要途径，对细胞周期、凋亡、DNA修复等细胞生理过程均有重要作用。蛋白酶体的调控异常与肿瘤等多种疾病的发生密切相关，同时也是部分抗癌药物的靶标，但其具体分子机制仍不清楚。申请人前期的研究发现，蛋白酶体亚基Rpn1与蛋白磷酸酶UBLCP1存在直接相互作用；后者抑制蛋白酶体的组装与活性；同时，在卵巢癌细胞中过表达UBLCP1显著抑制肿瘤细胞的存活。申请人将以此为切入点，综合应用生化、分子、细胞和肿瘤学方法，系统深入地探寻受UBLCP1直接调控的蛋白酶体亚基，研究蛋白酶体的组装、活性以及下游底物稳定性受UBLCP1去磷酸化调节的机制，并探讨蛋白酶体去磷酸化修饰后对肿瘤细胞存活与增殖以及对DNA损伤修复的影响。通过本项目的研究，希望能够揭示蛋白酶体的去磷酸化调控修饰对肿瘤发生发展的作用及分子机制，并为探索UBLCP1作为新型靶向抗肿瘤药物提供新思路。