Cytoplasmic Localization of p21 Protects Trophoblast Giant Cells from DNA Damage Induced Apoptosis
Figure 8
Cytoplasmic p21 provided TGCs with resistance to DNA damage induced apoptosis.
(A) Wild-type TSCs (▪, 6×105 cells), cultured in standard TSC medium, were treated with 5 µM etoposide for up to three days. Wild-type TGCs (□, 6×105 cells) were produced by FGF4 deprivation of TSCs for three days, 5 µM etoposide was then added to the medium for up to three days. The number of cells remaining attached to the dish was recorded and the results calculated as the percentage of cells that survived. (B) Same as in A except that wild-type TGCs (□) and p21−/− TGCs (○, broken line) had been deprived of FGF4 for only two days before treating them with the indicated concentration of etoposide for two days. Wild-type and p21−/− TSCs were indistinguishable during their proliferation and their differentiation into TGCs. (C) Wild-type TSCs (▪) and TGCs (□), cultured as in panels A and B, were exposed to indicated concentration of etoposide for three days and cell survival was assessed as in B. Wild-type TGCs infected with lentivirus containing shRNA against p27 (⋄), p57−/− TGCs (▵) and p21−/− TGCs (○, broken line) were treated as well. (D) Depletion of p27 protein in TGCs treated either with shRNA against p27 RNA or scramble control shRNA (Ctl) was assayed by Western immuno-blotting. Errors bars indicate standard error of the mean for triplicate samples of each datum point.