Regulation of alpha-crystallin gene expression by glucocorticoids in lens epithelial cells

ABSTRACT

PURPOSE: The purpose of this study was to examine the molecular basis for steroid-induced cataract and the specific aim was to investigate the potential effects of glucocorticoids on modulation of alpha-crystallin gene expression in lens epithelial cells. METHOD: Bovine lens epithelial explants, B-3 human lens epithelial cells, and alphaTN4 mouse lens epithelial cells were incubated in the absence or presence of dexamethasone. At the indicated time point, total cellular RNA was isolated and subjected to RT-PCR and Northern blot analysis to assess mRNA expression of alphaA- and alphaB-crystallin. RESULTS: The mRNA expression of alphaA-crystallin was drastically downregulated by treatment with dexamethasone in bovine, human, and mouse lens epithelial cells. The mRNA level of alphaA-crystallin was also decreased in response to hydrocortisone but not to estrogen. The stability of the alphaA-crystallin mRNA was decreased after dexamethasone treatment. CONCLUSIONS: These results suggest that the alteration of alphaA-crystallin gene expression by glucocorticoids may result in abnomal structure and differentiation of lens epithelial cells on steroid-induced cataract formation.