Objective: To investigate the effect of the ubiquitylation of eIF3I on cell proliferation through cyclin protein and cell cycle. Methods: Point mutation was made to construct mutant K282R and the ubiquitylation was compared with the wild type eIF3IWestern blotting was used to detect the level of ubiquitylation and cyclin Dl expression. Flow cytometry was used to study the cell cycle of Hela. Results: Over-expression of wild type eIF3I enhanced the expression of cyclin Dl and promoted cell cycle in Hela. Compared with that in the wild type eIF3I, the K282R mutant had reduced ubiquitylation and higher level of protein, and promoted cell cycle more strongly. Conclusion: Inhibiting eIF3I's degradation via ubiquitin-proteasome can enhance the expression of cyclin Dl and promote proliferation of cervical cancer cells, implicating a role of eIF3I in cell growth and tumorigenesis.%目的:研究eIF3I蛋白在细胞中的泛素化修饰,阐明其对人宫颈癌细胞系Hela增殖的影响.方法:通过点突变技术获得突变体K282R,与野生型eIF3I比较泛素化的水平,研究细胞内的泛素化修饰调控.经流式细胞仪分析细胞周期,研究野生型蛋白eIF3I和突变体K282R对Hela细胞的细胞周期影响.再从周期蛋白水平研究eIF3I对细胞增殖的调控作用.结果:突变体K282R比野生型eIF3I蛋白的外源表达量大.在Hela细胞中K282R突变体的泛素化水平低,抑制了该蛋白的泛素-蛋白酶体途径降解.过表达eIF3I能上调周期蛋白Cyclin D1的表达量,促进细胞进入由G1期进入S期.同时,泛素化程度低的突变体K282R具有较强的促进细胞增殖的作用.结论:抑制eIF3I的泛素-蛋白酶体途径降解能上调周期蛋白CyclinD1的表达,促进肿瘤细胞增殖,提示eIF3I在细胞增殖和肿瘤发生发展中发挥作用.
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