Ultraviolet radiation modulates nuclear factor kappa B activation in human lens epithelial cells.
Exposure to ultraviolet radiation (UVR) is a known risk factor for cataract, but the molecular mechanisms involved have not been elucidated. We hypothesized that exposure to UVR would modulate the activation of nuclear factor kappa-B (NF-kappa B) within the human lens epithelium, since NF-kappa B is a key regulator of cellular responses to UVR stress in other cell types. Human lens epithelial (HLE) cells were exposed to acute physiological doses of ultraviolet A (UVAR), B (UVBR), C (UVCR) radiation, or interleukin-1 beta (IL-1 beta) and NF-kappa B activation was measured by electrophoretic shift assay (EMSA). Phosphorylation of I kappa B in response to UVAR was measured by Western blotting. Irradiation of HLE cells with UVAR (0-1100 J/m(2)) did not reduce cell survival, while UVBR (400-1600 J/m(2)) and UVCR (300-900 J/m(2)) significantly reduced HLE cell survival. EMSA analysis of HLE nuclear proteins indicated activation of NF-kappa B, but not activator protein-1 (AP-1), by UVAR. The effects of UVBR and UVCR were less pronounced. Exposure of HLE cells to UVAR (0-900 J/m(2)) followed by a 30-min incubation resulted in a dose-dependent activation of NF-kappa B. UVAR-induced NF-kappa B activation in HLE cells was evident 10 min postirradiation, maximal at 60 min and returned to control levels by 120 min. Western blot analysis of phosphorylation of the NF-kappa B inhibitory protein, I kappa B, revealed that UVAR activates NF-kappa B via a mechanism involving the phosphorylation of I kappa B-alpha; this effect was dose-dependent. Supershift analysis demonstrated that UVAR and IL-1 beta activate the transcriptionally active p65/p50 NF-kappa B dimer. These studies demonstrate that UVAR activates NF-kappa B in HLE cells in a time- and dose-dependent manner via signaling through I kappa B-alpha. The activation of NF-kappa B in HLE cells by UVAR may have implications for the development and progression of cataract and other related ocular disorders.
Boileau
Thomas W-M
TW
Department of Human Nutrition, The Ohio State University, Columbus, OH 43210, USA.
Bray
Tammy M
TM
Bomser
Joshua A
JA
D015153:Blotting, Western; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D024202:Electrophoretic Mobility Shift Assay; D004847:Epithelial Cells / Q000378:metabolism* / Q000528:radiation effects*; D006801:Humans; D007908:Lens, Crystalline / Q000378:metabolism* / Q000528:radiation effects*; D016328:NF-kappa B / Q000378:metabolism* / Q000528:radiation effects*; D010766:Phosphorylation; D014178:Translocation, Genetic; D014466:Ultraviolet Rays
D016328:NF-kappa B