Leprecan distribution in the developing and adult kidney.

The temporal and spatial deposition of extracellular matrix proteins is critical for nephrogenesis and glomerular maturation. We previously characterized leprecan as a novel chondroitin sulfate proteoglycan which has been recently shown to have prolyl hydroxylase activity. In this study, we examine the distribution of leprecan during nephrogenesis and after a hypertrophic stimulus to the adult kidney. During development, leprecan was localized to mesenchymal aggregates, early comma- and S-phase structures as determined by immunohistochemistry and in situ hybridization. Leprecan mRNA was increased in cells around the vascular cleft of the S- and comma-phase glomeruli. Expression was found in podocytes, mesangial cells, and parietal epithelial cells of loop-phase glomeruli. Leprecan mRNA was substantially decreased in the glomeruli of the adult kidney compared to the developing kidney with a uniform distribution between the glomeruli and the tubules. Within adult glomeruli, leprecan was found in the mesangium mesangial matrix, podocytes, and in Bowman's capsule. In response to glomerular hypertrophy, produced by unilateral nephrectomy, leprecan synthesis was increased in the adult kidney. We suggest that the regulated expression of leprecan during glomerular development or hypertrophy coupled with its reported prolyl hydroxylase activity plays a role during basement membrane assembly.