Abstract
It was found previously that the expression of p21 mRNA and protein is deficient in CHO-K1 cells. And also, after 25 J/m2 of UV irradiation, significant death of CHO-K1 cells appears. And after overexpression of human p21 gene in CHO-K1 cells, this UV induced apoptosis can be reduced. p21 acts as a general cdk inhibitor. In order to know which cdk is involved in this UVC induced apoptosis, we constructed a p16 expression plasmid, and transfected it into CHO-K1 cells to see if the expression of p16 protein in CHO-K1 cells can reduce the UV-induced apoptosis. p16 is a inhibitor of cdk 4, 6 . From the flow cytometry result, we found that overexpression of p16 in CHO-K1 cells was unable to inhibit the UV-induced apoptosis. Moreover, the cdk4 kinase activity remained unchanged following UV irradiation. Thus, cdk 4, 6 play little or no roles in UVC induced apoptosis in CHO-K1 cells.