Differential control of murine aldose reductase and fibroblast growth factor (FGF)-regulated-1 gene expression in NIH 3T3 cells by FGF-1 treatment and hyperosmotic stress.

ABSTRACT

Aldose reductase (AR) is an NADPH-dependent aldo-keto reductase implicated in cellular osmoregulation and detoxification. Two distinct murine genes have been identified that are predicted to encode proteins with significant amino acid sequence identity with mouse AR mouse vas deferens protein and fibroblast growth factor (FGF)-regulated-1 protein (FR-1). Here we report that the AR and FR-1 genes are differentially regulated in NIH 3T3 fibroblasts. FGF-1 stimulation of quiescent cells induces both AR and FR-1 mRNA levels, but the effect on FR-1 mRNA expression is significantly greater. FGF-1 treatment also increases FR-1 protein expression, as determined by Western-blot analysis using FR-1-specific polyclonal antiserum. Calf serum stimulation of quiescent cells increases AR mRNA expression but not FR-1 mRNA expression. Finally, when NIH 3T3 cells are grown in hypertonic medium, AR mRNA levels are significantly increased whereas FR-1 mRNA levels are only slightly up-regulated. These results indicate that the AR and FR-1 genes are differentially regulated in murine fibroblasts by two different growth-promoting agents and by hyperosmotic stress. Therefore these structurally related enzymes may have at least some distinct cellular functions; for example, although both AR and FR-1 activity may be important for the metabolic changes associated with cellular proliferation, AR may be the primary aldo-keto reductase involved in cellular osmoregulation.