钙周期素结合蛋白的细胞周期依赖性转位现象

目的研究钙周期素结合蛋白（CacyBP／SIP）在胃癌细胞SGC7901中亚细胞定位与细胞周期的关系。方法利用双胸腺嘧啶脱氧核苷（胸苷）阻滞法将胃癌细胞SGC790l进行细胞周期同步化，流式细胞术检测细胞周期同步化效果。免疫荧光染色法观察CacyBP／SIP在不同时期的亚细胞定位。蛋白质印迹法检测CacyBP／SIP总蛋白及核蛋白在不同时期的表达水平。结果采用双胸苷阻滞法使SGC7901细胞阻滞于G，／s期，撤药后培养4h，细胞进入S期。大多数细胞在8～12h时进入G2／M期，16h又重新进入G1期。免疫荧光染色发现，在G1和S期时，CacyBP／SIP主要分布在细胞浆中，而在以G2期为主的细胞中，CacyBP／SIP聚集在核周或进入胞核，说明CacyBP／SIP存在细胞周期依赖性的核转位。在细胞的各时相中CacyBP／SIP总蛋白无明显变化，但在G2期时CacyBP／SIP的核蛋白表达水平增高。结论CacyBP／SIP存在细胞周期依赖的转位现象，可能参与了G2／M期的调控作用。

Cell cycle dependent translocation of calcyclin binding protein

Objective To investigate the relationship of the subcellular localization of calcyclin binding protein （CacyBP/SIP） with cell cycle in gastric cancer cell line SGC7901. Methods Double thymidine block was used to synchronize the cell cycle in SGC7901 cells. Flow cytometry was employed to identify the cell cycle synchronization. The localization of CacyBP/SIP protein was observed at the different phase of cell cycle by immunofluorescence staining. The expression levels of total protein and nucleoprotein CacyBP/SIP were detected by Western blotting at different cell cycles. Results Double thymidine block arrested the SGC7901 cells at GI/S phase, then the cells were at S phase in 4h after drug withdrawal. Most of cells got into G2 phase in 8 to 12h after culture and re-entered G1 phase in 16h. Immunofluorescence staining found that CacyBP/SIP was mainly distributed in the cytoplasm at GI/S phase, but then gathered into the perinuclear or nuclear at G2 phase, which indicates that CacyBP/SIP had the characteristics of nuclear translocation of cell cycle dependence. The total expression level of CacyBP/SIP protein had no obvious change at each phase, but the nuclear CacyBP/SIP protein at G2 phase was highest than at any other phases. Conclusion CacyBP/SIP displays cell cycle dependent translocation, and may participate in regulating G2/M phase.