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

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 (P0.05) 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.;