ZINC INDUCES CATALASE EXPRESSION IN CULTURED FETAL HUMAN RETINAL-PIGMENT EPITHELIAL-CELLS

Purpose. We have previously shown that an experimental, low-zinc envir onment decreased catalase activity in cultured human fetal retinal pig ment epithelial (RPE) cells. The purpose of this study was to investig ate the effect of zinc supplementation on catalase expression in cultu red human fetal RPE cells. Methods. Confluent fetal RPE cells incubate d in Goon's modified Ham's F12 (CMF-12) were treated (18 h) with zinc chloride (ZnCl2) (15, 30, or 100 mu M) to assess changes in catalase e nzyme activity or for 6 h to assess the induction of catalase mRNA by Northern analysis and in situ hybridization. RPE cells were also treat ed with 30 mu M ZnCl2 for 2, 6, 24, 48 and 72 h to assess the time cou rse of changes in catalase enzyme activity, changes in mRNA levels and status of the Spl transcription factor. Results. Catalase activity wa s increased above control by the addition of 15, 30 and 100 mu M ZnCl2 . Catalase gene expression was induced by 30 mu M zinc in 6 h, but dec reased to nontreated control levels by 24 h. The transcription factor Spl was also activated by zinc treatment (30 mu M) which peaked at 2 h and declined to non-treated control levels by 24 h. Catalase enzyme a ctivity peaked at 24 h and decreased to control levels by 72 h. Conclu sions. Our results demonstrate that zinc treatment of RPE cells increa ses catalase expression and activates the transcription factor Spl. Th e results suggest zinc may play a role in the transcriptional regulati on of catalase in RPE cells.