FIG. 6.

Mitochondrial targeting and apoptosis effects of cytoplasmic RXRα and Nur77 mutants. (A) Cytoplasmic Nur77 mutants but not RXRα mutants induce apoptosis. The indicated GFP-RXRα or GFP-Nur77 mutant was transfected into LNCaP cells. After 48 h, cells were stained by DAPI and analyzed for nuclear morphological change by microscopy. Arrows indicate cells with extensive nuclear condensation or fragmentation. Percentages of apoptotic cells were determined by examining 200 GFP-positive cells for nuclear fragmentation and/or chromatin condensation. Bars represent averages ± the means from three experiments. (B) Cytoplasmic Nur77 mutant but not RXRα mutant induces cytochrome c (Cyt) release. GFP-Nur77/ΔDBD or GFP-RXRα/C1 expression vector was transfected into LNCaP cells. Cells were then stained for mitochondria (Hsp60) and cytochrome c and analyzed by confocal microscopy. Cytochrome c release was observed in 80% of cells showing Nur77/ΔDBD mitochondrial targeting, whereas it was not found in cells transfected with RXRα/C1. One of two similar experiments is shown.