电离辐射对小鼠胸腺细胞p16、CyclinD1、CDK4表达的影响

EFFECT OF IONIZING RADIATION ON EXPRESSIONS OF p16、CyclinD1 and CDK4 IN MOUSE THYMOCYCTES

采用流式细胞术 (FCM)检测了不同剂量X射线全身照射后 ,昆明种小鼠胸腺细胞p16、CyclinD1、CDK4蛋白表达的时程变化和量效关系。结果表明 ,2GyX射线照射后 8h小鼠胸腺细胞p16表达明显增高 ,2 4h达到峰值 ,持续至照射后 4 8h ,72h降至正常水平 ;CDK4表达水平在照射后8h明显降低 ,12h降至最低 ,照射后 4 8h恢复近正常水平 ;周期蛋白CyclinD1表达轻度下调。不同剂量 (0 .5 - 4Gy)照射后p16蛋白表达随着剂量的增加而增加 ,2Gy组与假照射组相比显著增多 (p<0 .0 1) ;CDK4蛋白表达在 2Gy照射后明显低于假照射组 (p <0 .0 1) ;CyclinD1表达在 0 .5 - 2Gy照射后可见下降趋势。结果提示 :p16 /CyclinD1/CDK4 /pRb通路在电离辐射诱导胸腺细胞G1期阻滞中可能起着十分重要的作用。

Using flow cytometry (FCM) , The changes in expressions of p16,CyclinD1 and CDK4 in the thymocytes of mice treated with different doses of whole-body irradiation or with a fixed dose and different post-irradiation intervals were analyzed. The results showed that the expression of p16 protein in mouse thymocytes began to increase significantly at 8h after 2Gy X irradiation, reached the peak level at 24h, kept a high level until 48h, and recovered at 72h. The CDK 4 protein expression decreased at 8h after 2Gy irradiation, reached the bottom level at 12h, and recovered at 48h. The expression of CyclinD1 protein showed a little reduction only after 2Gy irradiation . Overexpression of p16 depended on the doses of radiation (0.5-4Gy). The expression of p16 in 2Gy group was significantly increased in comparison with that in the sham-irradiated group ( p <0.01). The reduction of CDK4 expression was significant in 2Gy group ( p <0.01). CyclinD1 expression showed its decrease after 0.5-2Gy irradiation. These results suggested that p16/CyclinD1/CDK4/pRb pathway might play an important role in G 1 arrest of thymocytes induced by ionizing radiation.