Regulation of osteoclast differentiation by fibroblast growth factor 2: stimulation of receptor activator of nuclear factor kappaB ligand/osteoclast differentiation factor expression in osteoblasts and inhibition of macrophage colony-stimulating factor function in osteoclast precursors.
This study investigated the mechanism of direct and indirect actions of fibroblast growth factor 2 (FGF-2) on osteoclast differentiation using two mouse cell culture systems. In the coculture system of osteoblasts and bone marrow cells, FGF-2 stimulated osteoclast formation. This effect was decreased markedly by osteoprotegerin (OPG) or NS-398, a selective cyclo-oxygenase 2 (COX-2) inhibitor. FGF-2 (> or = 10(-9) M) stimulated receptor activator of nuclear factor kappaB ligand/osteoclast differentiation factor (RANKL/ODF) messenger RNA (mRNA) expression from 2 h to 7 days in cultured osteoblasts. NS-398 did not affect the early induction but decreased the later one, indicating that the later effect is mediated by COX-2 induction in osteoblasts. To study the direct action of FGF-2 on osteoclast precursors, we used mouse macrophage-like cell line C7 cells that can differentiate into osteoclasts in the presence of soluble RANKL/ODF (sRANKL/ODF) and macrophage colony-stimulating factor (M-CSF). Although osteoblasts expressed all FGF receptors (FGFR-1 to -4), only FGFR-1 was detected in C7 cells at various differentiation stages. FGF-2 alone or in combination with sRANKL/ODF did not induce osteoclastogenesis from C7 cells; however, FGF-2 from lower concentrations (> or = 10(-11) M) significantly decreased osteoclast formation induced by M-CSF in the presence of sRANKL/ODF. FGF-2 did not alter mRNA levels of M-CSF receptor (Fms) or RANK in C7 cells. Immunoprecipitation/ immunoblotting analyses revealed that tyrosine phosphorylation of several cellular proteins including Fms in C7 cells induced by M-CSF was inhibited by FGF-2 in the presence of sRANKL/ODF. We conclude that FGF-2 regulates osteoclast differentiation through two different mechanisms: (1) an indirect stimulatory action via osteoblasts to induce RANKL/ODF partly through COX-2 induction and prostaglandin production and (2) a direct inhibitory action on osteoclast precursors by counteracting M-CSF signaling.
Chikazu
D
D
Department of Orthopedic Surgery, Graduate School of Medicine, University of Tokyo, Japan.
Katagiri
M
M
Ogasawara
T
T
Ogata
N
N
Shimoaka
T
T
Takato
T
T
Nakamura
K
K
Kawaguchi
H
H
D000818:Animals; D016723:Bone Remodeling / Q000235:genetics / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D051546:Cyclooxygenase 2; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006023:Glycoproteins / Q000235:genetics; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D053244:Osteoprotegerin; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism; D053245:RANK Ligand; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D051496:Receptor, Fibroblast Growth Factor, Type 1; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics; D018124:Receptors, Tumor Necrosis Factor; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D002352:Carrier Proteins; D006023:Glycoproteins; D007527:Isoenzymes; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D017468:Receptors, Fibroblast Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D016222:Fibroblast Growth Factor 2; D016173:Macrophage Colony-Stimulating Factor; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496349:Fgfr1 protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1