Characterization of mRNA and genes for aldose reductase in rat

Aldose reductase (AR; E.C. 1. 1. 1. 21) has been implicated in a variety of diabetic complications. To investigate the expression of this enzyme in target tissues susceptible to such complications, mRNA encoding AR was characterized by Northern blot hybridization in various tissues and cultured cell preparations. The size of mRNA for AR (approximately 1500 bases) was in good agreement with the size determined by sequence analysis. A cDNA probe for AR from rat lens hybridized to the same size species of RNA isolated from cultured dog lens epithelial cells, cultured human retinal capillary pericytes (mural cells), and Y 79 human retinoblastoma cells. In rat tissues, a substantial amount of mRNA was expressed not only in lens, but also in retina, sciatic nerve and kidney medulla. AR mRNA seemed to be less abundant in rat skeletal muscle and brain, and was scarcely present in liver. Furthermore, Southern blot analysis of rat genomic DNA indicated that there are multiple sequences related to that for AR, probably indicating the existence of a multi-gene family.