Transforming growth factor-beta stimulates the production of osteoprotegerin/osteoclastogenesis inhibitory factor by bone marrow stromal cells.
Osteoprotegerin (OPG)/osteoclastogenesis inhibitory factor (OCIF) is a recently identified cytokine that belongs to the tumor necrosis factor receptor superfamily and regulates bone mass by inhibiting osteoclastic bone resorption. The present study was undertaken to determine whether OPG/OCIF is produced in bone microenvironment and how the expression is regulated. A transcript for OPG/OCIF at 3.1 kilobases was detected in bone marrow stromal cells (ST2 and MC3T3-G2/PA6) as well as in osteoblastic cells (MC3T3-E1). Transforming growth factor-beta1 (TGF-beta1) markedly increased the steady-state level of OPG/OCIF mRNA in a dose-dependent manner, while TGF-beta1 suppressed the mRNA expression of tumor necrosis factor-related activation-induced cytokine (TRANCE)/receptor activator of NF-kappaB ligand (RANKL), a positive regulator of osteoclastogenesis to which OPG/OCIF binds. The effect of TGF-beta1 on the expression of OPG/OCIF mRNA was transient, with a peak level at 3-6 h. The up-regulation of OPG/OCIF mRNA by TGF-beta1 in ST2 cells did not require de novo protein synthesis and involved both a transcriptional and a post-transcriptional mechanism. Western blot analysis and an enzyme-linked immunosorbent assay revealed that TGF-beta1 significantly increased the secretion of OPG/OCIF protein by ST2 cells at 6-24 h. In murine bone marrow cultures, TGF-beta1 markedly inhibited the formation of tartrate-resistant acid phosphatase-positive multinucleated osteoclast-like cells in the presence of 1,25-dihydroxyvitamin D3, whose effect was significantly reversed by a neutralizing antibody against OPG/OCIF. These results suggest that TGF-beta1 negatively regulates osteoclastogenesis, at least in part, through the induction of OPG/OCIF by bone marrow stromal cells and that the balance between OPG/OCIF and TRANCE/RANKL in local environment may be an important determinant of osteoclastic bone resorption.
Takai
H
H
Department of Geriatric Research, National Institute for Longevity Sciences, Obu, Aichi 474-8522, Japan.
Kanematsu
M
M
Yano
K
K
Tsuda
E
E
Higashio
K
K
Ikeda
K
K
Watanabe
K
K
Yamada
Y
Y
D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects*; D002454:Cell Differentiation; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008954:Models, Biological; D010010:Osteoclasts / Q000166:cytology*; D053244:Osteoprotegerin; D012333:RNA, Messenger / Q000096:biosynthesis; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis*; D017154:Stromal Cells / Q000187:drug effects*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D006023:Glycoproteins; D053244:Osteoprotegerin; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506031:Tnfrsf11b protein, mouse; D016212:Transforming Growth Factor beta