Induction of apoptosis in PU.1-overexpressing cells. (A) Morphology of PU.1-sense clone 1 cells cultured in the ordinary medium. (B) Morphology of the same cells cultured with 1.5% DMSO and 100 μmol/L ZnCl2 for 48 hours. Arrows point to the flat cells attaching to the bottom of culture dishes, arrowheads to the spindle-like cells, and arrows with an asterisk to the dead cells. (C) DNA fragmentation analysis of the parental MEL-B8/3 cells and transfectants cultured under various conditions. DNA was extracted from the cells cultured for 48 hours in the ordinary medium or in the medium containing 1.5% DMSO and/or 100 μmol/L ZnCl2 and was electrophoresed in a 1.5% agarose gel. (D) The ultrastructural appearance of a PU.1-sense clone 1 cell showing characteristic features of apoptosis after 48 hours of culture with 1.5% DMSO and 100 μmol/L ZnCl2 . Note the dense chromatin aggregation under the nuclear membrane and no remarkable changes of the mitochondria and other organelles. Scale bar, 1 μm.
