p53及其下游基因在电离辐射诱导小鼠胸腺细胞G1期阻滞中的作用

采用流式细胞术和Ｎｏｒｔｈｅｒｎ ｂｌｏｔ检测了Ｘ射线全身照射后的昆明系小白鼠胸腺细胞的细胞周期、ｐ５３及其下游基因表达的变化。结果表明：⑴２ＧｙＸ射线全身照射后４ｈ，小鼠胸腺细胞Ｇ１期细胞百分数明显高于假照射组，２４ｈ达峰值，持续至照射后４８ｈ；⑵２Ｇｙ照射后ｐ５３蛋白表达在照射后１～８ｈ明显增高，ｐ２１蛋白表达在照射后４～４８ｈ明显增高，而ＧＡＤＤ４５蛋白表达示未南明显变化；⑶２ＧｙＸ射线照射

THE ROLE OF p53 AND ITS DOWN-STREAM GENE IN G1 ARREST OF MOUSE THYMOCYTES INDUCED BY IONIZING RADIATION

To elucidate the role of p53 and its down-stream gene in G1 arrest of mouse thymocytes induced by ionizing radiation, Flow cytometry (FCM) and northern blot were used to analyze the changes of cell cycle, expression of p53 and its down-stream gene of thymocytes of Kunming mice after whole body irradiation (WBI) with X-rays. The results indicatcd: (1) The number of G1 phase cells of thymocytes began to significantly incrcased at 4h after WBI with 2Gy X-rays, and reached the peak level at 24h, and kept a higher level until at least 48h. (2)The percentages of p53 + cells of mouse thymocytes increased from 1h to 8h, and p21+ from 4h to 8h after 2Gy WBI. Howevcr, no change was found in the percCntage of GADD45 + cells of mouse thymocytes. (3) WAF1 mRNA level began to incrcase at 1h.and reached the peak level at 2h, and kept a higher level till to 24h, and rccovered to sham-irradiation level at 48h after WBI. There was no change of GADD45 mRNA level, in accordance with its protein level change.These results suggested that p53-WAF1 pathway may be play an important role in the G1 arrest of mouse thymocytes induced by ionizing radiation.