title: Infection-induced up-regulation of the costimulatory molecule 4-1BB in osteoblastic cells and its inhibitory effect on M-CSF/RANKL-induced in vitro osteoclastogenesis.
abstract: Bacterial infection sometimes impairs bone metabolism. In this study, we infected the osteoblastic cell line MC3T3-E1 with Mycobacterium bovis bacillus Calmette-Guérin (BCG) and identified genes that were up-regulated in the BCG-infected cells by the suppression subtractive hybridization method. A gene encoding 4-1BB (CD137), a member of the tumor necrosis factor-alpha receptor family, was found to be one of the up-regulated genes. Up-regulation of 4-1BB was also observed by infection with Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus, and by treatment with lipopolysaccharides and heat-killed BCG. Bone marrow cells and the macrophage-like cell lines J774 and RAW264.7 were found to express 4-1BB ligand (4-1BBL). Recombinant 4-1BB (r4-1BB) that was immobilized on culture plates strongly inhibited macrophage colony stimulating factor (M-CSF)/receptor activator of nuclear factor-kappaB ligand (RANKL)-induced in vitro osteoclast formation from bone marrow cells. Anti-4-1BBL antibody also inhibited osteoclast formation to a lesser extent, indicating involvement of reverse signaling through 4-1BBL during inhibition of osteoclast formation. A casein kinase I (CKI) inhibitor markedly suppressed the inhibitory effect of r4-1BB on M-CSF/RANKL-induced osteoclast formation, suggesting that CKI might be involved in 4-1BB/4-1BBL reverse signaling. r4-1BB showed no effects on M-CSF- or RANKL-induced phosphorylation of I-kappaB, ERK1/2, p38, or JNK, whereas RANKL-induced phosphorylation of Akt, a downstream target of phosphatidylinositol 3-kinase (PI3K), was completely abolished by r4-1BB, suggesting that 4-1BB/4-1BBL reverse signaling may interfere with PI3K/Akt pathway. r4-1BB also abolished RANKL-mediated induction of nuclear factor of activated T cells-2. This study may elucidate a novel role of 4-1BB in cell metabolism, especially osteoclastogenesis.
authors.affiliation: Department of Developmental and Reconstructive Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8588, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Saito
authors.forename: Naoya
authors.initials: N
authors.lastname: Ohara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hotokezaka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukumoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Yuasa
authors.forename: Mariko
authors.initials: M
authors.lastname: Naito
authors.forename: Taku
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Koji
authors.initials: K
authors.lastname: Nakayama
mesh_terms: D053330:4-1BB Ligand; D000818:Animals; D015703:Antigens, CD; D001424:Bacterial Infections / Q000378:metabolism*; D015415:Biomarkers; D001854:Bone Marrow Cells / Q000166:cytology / Q000382:microbiology; D002352:Carrier Proteins / Q000494:pharmacology; D047388:Casein Kinases; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D004927:Escherichia coli Infections / Q000378:metabolism; D015723:Gene Library; D066298:In Vitro Techniques; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000382:microbiology; D008562:Membrane Glycoproteins / Q000494:pharmacology; D051379:Mice; D009163:Mycobacterium bovis; D041681:NIH 3T3 Cells; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism / Q000382:microbiology*; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism / Q000382:microbiology*; D011494:Protein Kinases / Q000378:metabolism; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D017475:Receptors, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism*; D012480:Salmonella Infections / Q000378:metabolism; D012486:Salmonella typhimurium; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013203:Staphylococcal Infections / Q000378:metabolism; D014376:Tuberculosis / Q000378:metabolism; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D053330:4-1BB Ligand; D015703:Antigens, CD; D015415:Biomarkers; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C505715:Tnfrsf9 protein, mouse; C505689:Tnfsf11 protein, mouse; C505975:Tnfsf9 protein, mouse; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9; D014409:Tumor Necrosis Factor-alpha; D016173:Macrophage Colony-Stimulating Factor; D011494:Protein Kinases; D047388:Casein Kinases