Localization of the NO-cGMP signaling pathway molecules, NOS III-phosphorylation sites, ERK1/2, and Akt/PKB in osteoclasts.

Background: Nitric oxide (NO) mediates different cellular functions by activating soluble guanylate cyclase (sGC) that converts guanosine-5'- triphosphate (GTP) to cyclic guanosine-3' ,5'-monophosphate (cGMP). Membrane-bound GCs produce cGMP in response to natriuretic peptides in osteoblasts, but neither the NO-target enzyme sGC, nor the phosphorylation sites of NOS III, nor their regulation by extracellular signalregulated kinases 1 and 2 (ERK1/2) and Akt/protein kinase B (Akt/PKB) in osteoclasts have been established. Methods: Rat molars with periodontium were perfusion- and postfixed, decalcified, and frozen-sectioned. Free-floating sections were stained using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) and tartrate-resistant acid phosphatase (TRAP) histochemical techniques and immunoreacted with antisera against NOsynthase (NOS) I-III, NOS III phoshorylated at Thr495, NOS III phoshorylated at Serine1177 (Ser1177), ERK1/2, phosphorylated ERK1/2, Akt/PKB, phosphorylated Akt/PKB, sGC...