Changes of the Golgi complex during apoptosis and necrosis induced by staurosporine (STS). (a) Untreated HEp-2 cell control, and (b)–(e) cells treated with 2 μM STS for up to 6 hours for the induction of apoptosis. Apoptotic cells can be classified into four basic stages based on the nuclear change and the staining of Golgi antigens. (b) Stage I represents Golgi swelling (double-head arrows) that appears at an early stage when distinctive changes are seen in the shape of the nucleus (arrow). The area occupied by the swelled Golgi can be ~ 5–10 times the normal size for the Golgi complex in HEp-2 cells. (c) Stage II shows the characteristic condensation of the Golgi complex adjacent to the nucleus that was elongated and appeared as a kidney shape or a crescent shape (arrow). (d) Stage III is seen in cells with defined nuclear fragmentation into two approximately equal nuclear fragments, and immunostaining of the Golgi antigen was primarily located at the cleavage site between the two nuclear fragments. (e) In stage IV, nuclei were fragmented into multiple fragments with smaller pieces (middle panel, arrows) and Golgi staining appeared as vesicular structures. (f) HEp-2 cells 6 hours after treatment of 10 μM STS for the induction of necrosis. In contrast to apoptosis, striking fragmentation of the Golgi complex was observed with nuclear condensation rather than nuclear fragmentation. Immunostaining was performed using rabbit anti-golgin-97 and Alexa™ 488 conjugated goat anti-rabbit IgG antibody (left panels), and the nuclei were counterstained by 4',6-diamidino-2-phenylindole (DAPI) (middle panels). Right panels show the merged images. AGA, anti-Golgi complex autoantibodies.