title: cAMP-PKA signaling pathway regulates bone resorption mediated by processing of cathepsin K in cultured mouse osteoclasts.
abstract: Cathepsin K (Cat K) is the major cysteine protease expressed in osteoclast and is thought to play a key role in matrix degradation during bone resorption. It is shown that the intracellular maturation of Cat K was prevented by the cAMP antagonist, Rp-cAMP, and the protein kinase A (PKA) inhibitors of KT5720 and H89. In contrast, forskolin, an adenylate cyclase agonist, rather induced Cat K processing and maturation in osteoclast. Furthermore, to determine whether Cat K processing and maturation signaling involves protein kinase C (PKC), mouse total bone cells were treated with calphostin C, a specific inhibitor of PKC, however, no effect was observed, indicating that PKC calphostin C did not affect to osteoclast-mediated Cat K processing and maturation in osteoclast. Thus, it is indicated that the cAMP-PKA signaling pathway regulate Cat K maturation in osteoclast. Since secreted proenzymes have the potential to reenter the cell via M6P receptor, to prevent this possibility, we tested cAMP antagonist Rp-cAMP and the PKA inhibitors KT5720 and H89 in the absence or presence of M6P. Inhibition of Cat K processing by Rp-cAMP, KT5720 or H89 was observed in a dose-dependent manner. Furthermore, the addition of M6P resulted in enhanced potency of Rp-cAMP, KT5720 and H89, which dose-dependently inhibited in vitro bone resorption with potency similar to that observed for inhibition of Cat K processing.
authors.affiliation: Department of Orthodondritics, Kyung-Hee University College of Dental Medicine, Dongdaemun-ku, Seoul 130-701, South Korea.
authors.forename: Young-Guk
authors.initials: YG
authors.lastname: Park
authors.forename: Young-Hun
authors.initials: YH
authors.lastname: Kim
authors.forename: Sung-Koo
authors.initials: SK
authors.lastname: Kang
authors.forename: Cheorl-Ho
authors.initials: CH
authors.lastname: Kim
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D001862:Bone Resorption / Q000378:metabolism / Q000503:physiopathology; D002227:Carbazoles / Q000494:pharmacology; D056657:Cathepsin K; D002403:Cathepsins / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D007211:Indoles / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008358:Mannose / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D008985:Monensin / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D011758:Pyrroles / Q000494:pharmacology; D017527:Receptor, IGF Type 2 / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D000906:Antibodies; D002227:Carbazoles; D007211:Indoles; D007546:Isoquinolines; D009281:Naphthalenes; D047428:Protein Kinase Inhibitors; D011758:Pyrroles; D017527:Receptor, IGF Type 2; D013449:Sulfonamides; D005576:Colforsin; C057416:KT 5720; D002738:Chloroquine; D008985:Monensin; C047533:mannose 6-sulfate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002403:Cathepsins; D056657:Cathepsin K; C534132:Ctsk protein, mouse; C058819:calphostin C; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D008358:Mannose