Comparative response to UV irradiation of cytoskeletal elements in rabbit and skate lens epithelial cells

This work reports a differential effect of ultraviolet A (UVA) irradiation on the three major cytoskeletal structures, actin and vimentin filaments and microtubules of lens cells in primary culture. The effect on cells from lens of the skate (a bottom-dwelling marine elasmobranch) was compared with that on rabbit lens, in order to assess UVA sensitivity as a function of exposure to these wavelengths in the native habitat.

Exposure intervals of irradiation time up to 6 hours were selected, at fluences from 13.5 to 54.4 J/cm2 and at 365 +/- 45 nm wavelength, to represent mild to moderate physiological levels. Cultures were fixed and processed with anti-alpha-tubulin-FITC and rhodamine phalloidin, or with anti-vimentin FITC and rhodamine phalloidin conjugates.

With epifluorescence microscopy, it was found that microtubules were most sensitive to UVA irradiation (in depolymerizing), followed by actin, with vimentin hardly at all affected. Irradiation for 6 hours followed by incubation for 3 days in fresh medium showed no recovery of actin but good recovery of microtubule organizing centers, followed by mitosis in many (rabbit) cells. Skate cells were more sensitive and showed no recovery.

In view of the role of cytoskeletal elements in intracellular structure, cell division and transport, their disruption supports the hypothesis that UVA may damage lens epithelial cells in vivo so as to contribute to cataract formation. In addition, the data suggest that the lenses of animals exposed to sunlight require effective cytoskeletal repair mechanisms to avoid loss of function.