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

Abstract

Exposure of fish to some environmental contaminants results in alterations to the levels of retinoid (Vitamin A) stores, which could result in an increase in cellular concentrations of biologically active metabolites such as retinoic acid (RA). However, a link has not been established between changes in retinoid metabolism and impacts on the health of biota. In vitro studies with mammalian cells have demonstrated a relationship between exposure to RA and expression of the extracellular matrix protein, fibronectin (FN); a protein critical for cell migration, adhesion, and transformation. In this study, in vitro exposures of rainbow trout gonadal cells (RTG-2) to RA reduced levels of FN in culture medium; as measured using SDS-PAGE and immunoblot analysis with antisera prepared against RTG-2 cellular fibronectin. This apparent down-regulation of FN secretion occurred in a dose-dependent manner over a range of RA concentrations (10 −10–10 −6 M). FN down-regulation was not accompanied by changes in the morphology of RTG-2. Future studies should be directed at determining the relationships between retinoid metabolism and FN expression and the potential effects of contaminant-induced changes to vitamin A metabolism on the health of fish.