X射线全身照射对小鼠胸腺细胞Cyclin B1和p34cdc2蛋白表达的影响

本文采用免疫组织化学法研究了低、高剂量X射线全身照射后不同时间小鼠胸腺细胞CyclinB1和p34^cdc2蛋白表达的变化。结果表明,与假照组相比,75mGy X射线全身照射后8h小鼠胸腺细胞CyclinB1蛋白表达开始升高,12h达高峰,48h恢复至正常水平;而2Gy照射后4h小鼠胸腺细胞CyclinB1蛋白表达开始降低,12h降至最低,24h有回升趋势,48h恢复至假照水平。p34^cdc2蛋白的表达,与假照组相比,75mGy照射后4～48h未见明显变化;而2Gy照射后的时程变化与相同剂量照射后CyclinB1蛋白表达的变化基本一致。提示：低剂量X射线全身照射可诱导小鼠胸腺细胞CyclinB1蛋白表达增强,从而促进细胞周期进程,但对p34^cdc2表达无影响;相反,较高剂量照射导致CyclinB1和p34^cdc2蛋白表达均下降,最终发生G2阻滞。

EFFECTS OF WHOLE BODY IRRADIATIONWITH X-RAYS ON CYCLIN B1 AND p34cdc2PROTEIN EXPRESSION IN MOUSE THYMOCYTES

The effects of whole body X irradiation (WBI) with low and high doses on Cyclin B 1 and p34 cdc2 protein expression in the thymocytes of mice were studied using immunohistochemistry. The results showed that comparing the control group Cyclin B 1 protein expression increased at 8 h after WBI with 75 mGy, reaching its peak at 12 h followed by its return to normal level at 48 h. Cyclin B 1 protein expression decreased at 4 h after WBI with 2 Gy, reaching its lowest level at 12 h, followed by a return to the control level at 48 h. At the same time, the changes of p34 cdc2 protein expression were observed. Comparing the control group, there were no changes in p34 cdc2 protein expression after WBI with 75 mGy, the time course of p34 cdc2 protein expression after WBI with 2 Gy was the same as Cyclin B 1 after the same dose. The results indicated that low dose irradiation could induce the increase of Cyclin B 1 protein expression accompanied with acceleration of cell cycle progression. In contrast, high dose irradiation could induce a decrease of expression of both proteins finally result in G 2 arrest. (