Down-regulation of fibronectin in rainbow trout gonadal cells exposed to retinoic acid

Exposure of fish to some environmental contaminants results in alterations to the levels of retinoid (Vitamin A) stores, which could result in an incr ease in cellular concentrations of biologically active metabolites such as retinoic acid (RA). However, a link has not been established between change s in retinoid metabolism and impacts on the health of biota. In vitro studi es with mammalian cells have demonstrated a relationship between exposure t o RA and expression of the extracellular matrix protein, fibronectin (FN); a protein critical for cell migration, adhesion, and transformation. In thi s study, in vitro exposures of rainbow trout gonadal cells (RTG-2) to RA re duced levels of FN in culture medium; as measured using SDS-PAGE and immuno blot analysis with antisera prepared against RTG-2 cellular fibronectin. Th is apparent down-regulation of FN secretion occurred in a dose-dependent ma nner over a range of RA concentrations (10(-10)-10(-6) M). FN down-regulati on was not accompanied by changes in the morphology of RTG-2. Future studie s should be directed at determining the relationships between retinoid meta bolism and FN expression and the potential effects of contaminant-induced c hanges to vitamin A metabolism on the health of fish. (C) 2000 Elsevier Sci ence B.V. All rights reserved.