title: P38 mitogen-activated protein kinase inhibitor, FR167653, inhibits parathyroid hormone related protein-induced osteoclastogenesis and bone resorption.
abstract: p38 mitogen-activated protein kinase (MAPK) acts downstream in the signaling pathway that includes receptor activator of NF-κB (RANK), a powerful inducer of osteoclast formation and activation. We investigated the role of p38 MAPK in parathyroid hormone related protein (PTHrP)-induced osteoclastogenesis in vitro and PTHrP-induced bone resorption in vivo. The ability of FR167653 to inhibit osteoclast formation was evaluated by counting the number of tartrate-resistant acid phosphatase positive multinucleated cells (TRAP-positive MNCs) in in vitro osteoclastgenesis assays. Its mechanisms were evaluated by detecting the expression level of c-Fos and nuclear factor of activated T cells c1 (NFATc1) in bone marrow macrophages (BMMs) stimulated with sRANKL and M-CSF, and by detecting the expression level of osteoprotegerin (OPG) and RANKL in bone marrow stromal cells stimulated with PTHrP in the presence of FR167653. The function of FR167653 on bone resorption was assessed by measuring the bone resorption area radiographically and by counting osteoclast number per unit bone tissue area in calvaria in a mouse model of bone resorption by injecting PTHrP subcutaneously onto calvaria. Whole blood ionized calcium levels were also recorded. FR167653 inhibited PTHrP-induced osteoclast formation and PTHrP-induced c-Fos and NFATc1 expression in bone marrow macrophages, but not the expression levels of RANKL and OPG in primary bone marrow stromal cells treated by PTHrP. Furthermore, bone resorption area and osteoclast number in vivo were significantly decreased by the treatment of FR167653. Systemic hypercalcemia was also partially inhibited. Inhibition of p38 MAPK by FR167653 blocks PTHrP-induced osteoclastogenesis in vitro and PTHrP-induced bone resorption in vivo, suggesting that the p38 MAPK signaling pathway plays a fundamental role in PTHrP-induced osteoclastic bone resorption.
authors: Department of Orthopedics, Osaka University Graduate School of Medicine, Osaka, Japan.
authors: Huiren
authors: H
authors: Tao
authors: Mina
authors: M
authors: Okamoto
authors: Masataka
authors: M
authors: Nishikawa
authors: Hideki
authors: H
authors: Yoshikawa
authors: Akira
authors: A
authors: Myoui
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D001862:Bone Resorption / Q000201:enzymology* / Q000473:pathology*; D002118:Calcium / Q000097:blood; D002452:Cell Count; D002478:Cells, Cultured; D006801:Humans; D006934:Hypercalcemia / Q000097:blood / Q000473:pathology; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D051379:Mice; D050778:NFATC Transcription Factors / Q000378:metabolism; D010010:Osteoclasts / Q000187:drug effects / Q000201:enzymology / Q000473:pathology*; D010012:Osteogenesis / Q000187:drug effects*; D053244:Osteoprotegerin / Q000378:metabolism; D044162:Parathyroid Hormone-Related Protein / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D053245:RANK Ligand / Q000494:pharmacology; D000071681:Tartrate-Resistant Acid Phosphatase; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: C104334:FR 167653; D007527:Isoenzymes; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D053244:Osteoprotegerin; D044162:Parathyroid Hormone-Related Protein; D047428:Protein Kinase Inhibitors; D016760:Proto-Oncogene Proteins c-fos; D011720:Pyrazoles; D011725:Pyridines; D053245:RANK Ligand; D048051:p38 Mitogen-Activated Protein Kinases; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase; D002118:Calcium