X射线全身照射对小鼠骨髓细胞CyclinD、CDK4表达的影响

Effect of whole body irradiation with X-rays on CyclinD,CDK4 gene expressions of bone marrow cells in mice

目的 研究X射线全身照射对小鼠骨髓细胞CyclinD、CDK4表达的影响 ,以探讨电离辐射诱导小鼠骨髓细胞G1 阻滞的分子机理。方法 采用Northernblot和半定量RT PCR方法分别检测CDK4、CyclinD基因转录水平变化 ;流式细胞仪检测了X射线全身照射小鼠骨髓细胞CyclinD、CDK4的表达及周期时程的变化。结果 2GyX射线全身照射后 12h骨髓细胞出现G1 期细胞百分数升高 (P <0 0 5 ) ,G2 +M期细胞百分数于照后 4h及 12h升高 (P <0 0 5 ) ;CyclinD基因转录水平从2h开始下降 ,48h达到最低 ,照后 72h恢复至正常水平 ,CDK4的变化趋势与CyclinD相似 ,只是从 8h开始下降 ,48h达到最低 ,照后 72h恢复假照组水平 ;CyclinD蛋白表达在照射后 2、4、2 4、48h显著降低 (P <0 0 1) ,CDK4蛋白表达在照射后 2h开始急剧下降 ,持续至照射后 48h仍未恢复到对照水平 (P <0 0 1)。结论 2GyX射线全身照射可诱导小鼠骨髓细胞发生G1 、G2 阻滞 ;CyclinD、CDK4基因及其蛋白产物可能在电离辐射诱导的小鼠骨髓细胞周期阻滞中起重要作用。

Objective For elucidating the molecular mechanism of G-1 arrest induced by ionizing radiation,CyclinD,CDK4 gene expressions of bone marrow cells in mice after whole body irradiation(WBI) with X-rays were studied. Methods Northern blot and semi-quantitative RT-PCR were used to detect CDK4,CyclinD mRNA levels, and flow cytometry (FCM) was adopted to analyze the protein product of CyclinD,CDK4 and the changes in cell cycle progression in Kunming mice following WBI with X-rays. Results The data showed an elevation of the percentage of cells in G-1 phase at 12 h (P<0.05) and an increase of cells in G-2+M phase at 4 h and 12 h after 2^0 Gy WBI.CyclinD mRNA level began to decrease at 2 h,reached its minimum at 48 h,and began to recover to the sham-irradiation level at 72 h after WBI with 2 Gy X-rays.CDK4 mRNA level had the same tendency with that of CyclinD,and it decreased begining from 8 h,reached its minimum at 48 h,and began to recover to the-irradiation level at 72 h.Both their protein expressions decreased begining from 2 h.The recovery of CyclinD was detectable at 72 h after 2 Gy irradiation,while CDK4 did not recover. Conclusions 2 Gy X-rays could cause the G-1 and G-2 arrest in bone marrow cells, and CyclinD,CDK4 might play important roles in the cell cycle arrest induced by ionizing radiation.;