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目的 :探讨 X射线全身照射诱导小鼠胸腺和脾细胞 G1期阻滞的分子机制。方法 :采用流式细胞术和斑点印迹杂交检测 X射线全身照射后昆明系小鼠胸腺和脾细胞中 MDM2 m RNA和蛋白表达的变化。结果 :2 Gy X射线全身照射后 4～ 8h小鼠胸腺细胞 MDM2蛋白的表达明显升高(P<0 .0 5)。时效和量效观察发现 ,无论是 75m Gy还是 2 Gy X射线全身照射 ,小鼠胸腺和脾细胞中 MDM2 m RNA水平在照后 1～ 48h均未见明显变化 ;0 .5～ 6Gy X射线全身照射后 4h,胸腺和脾细胞中 MDM2 m RNA转录亦未见显著改变。结论 :X射线全身照射可诱导小鼠淋巴细胞MDM2蛋白表达 ,从而限制 G1期阻滞的时间 ,使 DNA损伤修复后的细胞重新进入细胞周期
Objective: To investigate the molecular mechanism of G1 arrest in mouse thymus and spleen cells induced by X-ray. Methods: Flow cytometry and dot blot hybridization were used to detect the expression of MDM2 mRNA and protein in the thymus and spleen cells of Kunming mice after X-ray irradiation. Results: The MDM2 protein expression in thymocytes was significantly increased 4 ~ 8h after 2 Gy X-ray irradiation (P <0.05). The results of aging and dose-response showed that MDM2 m RNA level in mouse thymus and spleen cells did not change significantly from 1 to 48 hours after irradiation, no matter whether it was 75m Gy or 2 Gy whole body irradiation; 0.5-6Gy X-ray whole body 4h after irradiation, there was no significant change of MDM2 m RNA transcription in thymus and spleen cells. Conclusion: X-ray irradiation can induce the MDM2 protein expression in mouse lymphocytes, thus limiting the time of G1 arrest and re-entering the cell cycle after DNA damage repair