Altered expression of trefoil factor 3 and cathepsin L gene in rat kidney during aging.

Alterations in a wide array of physiological functions are normal consequences of aging. It is likely that, decline in cellular and physiological functions that occur during aging are the net result of age related differential gene expression and their consequent down stream effects. In this report we demonstrate that in aged kidney there is a decrease in the expression of trefoil factor 3 gene and an age-related increase in the expression of cathepsin L gene as revealed by differential display PCR (DD-PCR) and northern blot analysis. Trefoil factor 3 is mainly expressed in the alimentary canal and protects it from the degradative effect of HCl by stimulating the goblet cells to synthesize mucin. Though the exact role of trefoil factor 3 in kidney is not known, we speculate that it has a protective role in kidney. Cathepsin L is a cysteine protease which degrades connective tissue proteins like collagen, elastin and fibronectin. Increase in the expression of cathepsin L in aged kidney leading to considerable loss of organ function in old age. Down regulation of trefoil factor 3 and up regulation of cathepsin L may contribute to lack of protection and increased age related tissue damage to kidney in aging.