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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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4-1BB Ligand
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Animals
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Antigens, CD
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Bacterial Infections / metabolism*
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Biomarkers
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Bone Marrow Cells / cytology
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Bone Marrow Cells / microbiology
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Carrier Proteins / pharmacology
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Casein Kinases
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Cell Differentiation / drug effects
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Cell Differentiation / physiology
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Cell Division / drug effects
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Cell Division / physiology
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Escherichia coli Infections / metabolism
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Gene Library
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In Vitro Techniques
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Macrophage Colony-Stimulating Factor / pharmacology
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Macrophages / cytology
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Macrophages / microbiology
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Membrane Glycoproteins / pharmacology
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Mice
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Mycobacterium bovis
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NIH 3T3 Cells
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Osteoblasts / cytology*
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Osteoblasts / metabolism
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Osteoblasts / microbiology*
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Osteoclasts / cytology*
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Osteoclasts / metabolism
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Osteoclasts / microbiology*
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Protein Kinases / metabolism
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RANK Ligand
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Receptor Activator of Nuclear Factor-kappa B
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Receptors, Nerve Growth Factor / genetics
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Receptors, Nerve Growth Factor / metabolism*
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Receptors, Tumor Necrosis Factor / genetics
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Receptors, Tumor Necrosis Factor / metabolism*
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Salmonella Infections / metabolism
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Salmonella typhimurium
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Signal Transduction / drug effects
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Signal Transduction / physiology
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Staphylococcal Infections / metabolism
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Tuberculosis / metabolism
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Tumor Necrosis Factor Receptor Superfamily, Member 9
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Tumor Necrosis Factor-alpha / genetics
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Tumor Necrosis Factor-alpha / metabolism
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Tumor Necrosis Factor-alpha / pharmacology
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Up-Regulation
Substances
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4-1BB Ligand
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Antigens, CD
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Biomarkers
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Carrier Proteins
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Membrane Glycoproteins
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RANK Ligand
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Receptor Activator of Nuclear Factor-kappa B
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Receptors, Nerve Growth Factor
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Receptors, Tumor Necrosis Factor
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Tnfrsf11a protein, mouse
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Tnfrsf9 protein, mouse
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Tnfsf11 protein, mouse
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Tnfsf9 protein, mouse
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Tumor Necrosis Factor Receptor Superfamily, Member 9
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Tumor Necrosis Factor-alpha
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Macrophage Colony-Stimulating Factor
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Protein Kinases
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Casein Kinases