Kidney produces a novel acylated peptide, ghrelin

Ghrelin is a novel growth hormone-releasing peptide with a unique acylated structure. Here we reveal that preproghrelin gene is expressed in the mouse kidney and glomerulus. We also show by reverse-phase high performance liquid chromatography coupled with radioimmunoassay that the mouse kidney does produce ghrelin. The ghrelin immunoreactivity in the mouse kidney is 6.79 +/- 0.48 fmol/mg (n = 5), which is much more abundant than that in the mouse plasma of 0.339 +/- 0.029 fmol/mul (n = 6). Furthermore, prepro-ghrelin gene is expressed in cultured rat mesangial cells, fibroblast-like NRK-49P cells and mouse podocytes, but not in rat epithelial cell-like NRK-52E cells. Ghrelin receptor gene is also expressed in the rat kidney. These findings demonstrate that the kidney, glomerulus and renal cells express prepro-ghrelin gene and ghrelin is produced locally in the kidney, and suggest the endocrine and/or paracrine roles of ghrelin in the kidney. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.