CELL-CYCLE SPECIFICITY OF FAS-MEDIATED APOPTOSIS IN WIL-2 CELLS

Antibodies to Fas/APO1 receptor induce effective apoptosis in WIL-2 ce lls of the human B-lymphoid line, Quantitative assessment of the exten t of the death in cells synchronized by thymidine block revealed a sig nificant increase in their sensitivity to the cytocidal effect mediate d by Fas/APO1 during the G(1) phase of the cell cycle, Western analysi s of the content of the p53 antigen in the cytoplasm and nuclei of the cells showed that the Fas/APO1-induced death is accompanied by massiv e translocation of the p53 from the cytoplasm to the nucleus, These fi ndings suggest that cell vulnerability to the Fas/APO1-mediated apopto sis is subjected to regulation by cell cycle-dependent mechanisms, one of which is probably the function of the p53 antigen. (C) 1997 Federa tion of European Biochemical Societies.