C-type natriuretic peptide inhibits rat mesangial cell proliferation by a phosphorylation-dependent mechanism

We studied the effects of C-type natriuretic peptide (CNP) on rat cultured mesangial cell proliferation. (1) Exposure to CNP (10 nM–1 μM for 72 h) inhibited ³H]thymidine incorporation into mesangial cells in a concentration-dependent manner. Atrial natriuretic peptide (1 nM–1 μM), a peptide related to CNP, also decreased ³H]thymidine incorporation into these cells in a concentration-dependent manner. (2) Both CNP (10 nM-1 μM) and atrial natriuretic peptide (10 nM-1 μM) also decreased mesangial cell number. (3) The cyclic GMP analog, 8-bromo-cyclic GMP (100 μM and 1 mM), mimicked the inhibitory effects of CNP and atrial natriuretic peptide on ³H]thymidine incorporation into mesangial cells, whereas inhibitors of protein kinase C, protein kinase A, and protein kinase G reduced the effect of both natriuretic peptides. Moreover, the phoshpatase inhibitor, calyculin A, increased ³H]thymidine incorporation into mesangial cells. (4) CNP and atrial natriuretic peptide decreased interleukin-1-, interleukin-6-, platelet derived growth factor-, angiotensin II-induced ³H]thymidine incorporation into mesangial cells. These results suggest that CNP exerts inhibitory effects on mesangial cell proliferation and that this effects depend on protein phosphorylation pathways. Received: 17 March 1997 / Accepted: 29 August 1997