Effect of cyclic GMP produced by natriuretic peptides on osteoblast-like MC3T3-E1 cells

The C-type natriuretic peptide (10(-7) M) and atrial natriuretic peptide (10(-7) M) enhanced cGMP accumulation by 418 and 83 times the control value, respectively, in osteoblast-like MC3T3-E1 cells. The natriuretic peptide B receptor was assumed to be the major natriuretic peptide receptor. 8-Bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) activated alkaline phosphatase doubled the activity versus the control value on day 15. Phosphodiesterase activity was not stimulated by the addition of cGMP (1 MicroM). cGMP-dependent protein kinase (G kinase) activity of the supernatant fraction was 25.5 pmol/min/mg protein. The 42 kDa protein band was detected to be phosphorylated by G kinase on SDS-PAGE. These results supported the hypothesis that natriuretic peptides regulate the differentiation of MC3T3-E1 cells through a cGMP-dependent pathway.