Ultraviolet radiation (UV) induces reorganization of actin cytoskeleton in CHOAA8 cells

Effect of UV radiation on actin cytoskeleton was studied in CHOAA8 cells by fluorescence and electron microscopy. UV irradiated cells showed impaired adherence, disruption of the actin filaments and stronger F-actin labeling in the center of the cell. Attached cells, especially enlarged ones showed rather weak labeling of stress fibers and bundles of F-actin in the cytoplasm, but some cells with intensive labeling of these structures were also observed. Detached cells were rounded, showed strong F-actin labeling and often had buds. At the ultrastructural level UV-irradiated cells showed segmented nuclei, bodies resembling micronuclei, dilatation of endoplasmic reticulum, swollen and disturb mitochondria. Immunogold labeling of actin at the ultrastructural level was observed in non-radiated and UV irradiated cells. Actin labeling was seen in nuclei and cytoplasm. In nuclei gold particles were localized in the area of condense chromatin. Labeling for actin was not found after control incubation. Our observations show that UV radiation promotes changes in the distribution of actin in CHOAA8 cells. The results also suggest that not only reorganization of actin but changes in organelles are involved in the process of apoptosis initiated by UV radiation.