Molecular pathway of G1 arrest of thymocytes induced by ionizing radiation

Objective: To investigate the molecular pathway of G1 arrest of thymocytes induced by ionizing radiation. Methods: Flow cytometry (FCM) was used to analyze cell cycle stained with propidium iodide (PI). And FCM was also used to analyze protein expression of thymocytes for their immunofluorescence stained with monoclonal antibodies. Results: It was found that G1 phase cells of thymocytes increased significantly 12 h after whole body irradiation (WBI) with doses of 0.5, 1.0 and 2.0 Gy, and 24 h following 2 Gy WBI in mice. The results also showed the increases of p53+ cells of thymocytes at 1 h to 8 h, p21+ cells at 4 h to 48 h, and MDM2+ cells at 4 h and 8 h after 2 Gy WBI in mice. But no change was found in GADD45+ cells. Conclusion: G1 arrest could be induced by single WBI with 0.5 Gy to 2.0 Gy X-rays, and its molecular control might be established through the p53-p21 pathway