Induction of DC-STAMP by Alternative Activation and Downstream Signaling Mechanisms

Authors

  • Mitsuru Yagi,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Ken Ninomiya,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Nobuyuki Fujita,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Toru Suzuki,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Ryotaro Iwasaki,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Dentistry and Oral Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Kozo Morita,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Naobumi Hosogane,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Koichi Matsuo,

    1. Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo, Japan
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  • Yoshiaki Toyama,

    1. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
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  • Toshio Suda,

    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
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  • Takeshi Miyamoto MD

    Corresponding author
    1. Department of Cell Differentiation, The Sakaguchi Laboratory, Keio University School of Medicine, Tokyo, Japan
    2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
    3. Department of Musculoskeletal Reconstruction and Regeneration Surgery, Keio University School of Medicine, Tokyo, Japan
    • Department of Cell Differentiation, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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  • The authors state that they have no conflicts of interest.

Abstract

DC-STAMP is essential for fusion of osteoclasts and foreign body giant cells; however, it is not known whether dc-stamp expression in these two cell types is differentially regulated. Here, we show that dc-stamp expression and cell–cell fusion are regulated in a cell type–specific manner.

Introduction: The transcription factors c-Fos and NFATc1 cooperate to regulate osteoclast differentiation, whereas PU.1 and NF-κB are activated in macrophages and osteoclasts or in both cell types. Thus, we asked what role c-Fos, NFATc1, PU.1, and NF-κB played in regulating dendritic cell–specific transmembrane protein (dc-stamp) expression and fusion of osteoclasts and macrophage giant cells.

Materials and Methods: Transcriptional activation by c-Fos and NFATc1 was examined by dc-stamp promoter analysis. Multinuclear cell formation was analyzed in cells from c-Fos–deficient mice or in wildtype cells treated with the NFAT inhibitor FK506. The role of DC-STAMP in cell fusion was examined in vitro in a macrophage giant cell formation assay using DC-STAMP–deficient cells. Recruitment of c-Fos, NFATc1, PU.1, and NF-κB to the dc-stamp promoter in osteoclasts and macrophage giant cells was analyzed by chromatin-immunoprecipitation analysis.

Results: Both activator protein-1 (AP-1) and NFAT binding sites in the dc-stamp promoter were needed for dc-stamp expression after RANKL stimulation of osteoclasts. dc-stamp expression was induced in osteoclasts and macrophage giant cells, and cells from DC-STAMP–deficient mice failed to form either multinuclear osteoclasts or macrophage giant cells. In contrast, c-Fos is indispensable for dc-stamp expression and cell–cell fusion under conditions favoring in vitro and in vivo induction of osteoclasts but not macrophage giant cells. Consistently, an NFAT inhibitor suppressed multinuclear osteoclast formation but not macrophage giant cell formation. In addition, PU.1 and NF-κB binding sites were detected in the dc-stamp promoter, and both PU.1 and NF-κB were recruited to the dc-stamp promoter after granulocyte-macrophage colony stimulating factor (GM-CSF) + interleukin (IL)-4 stimulation.

Conclusions: dc-stamp expression is regulated differently in osteoclasts and macrophage giant cells. c-Fos and NFATc1, both of which are essential for osteoclast differentiation, are needed for dc-stamp expression and cell–cell fusion in osteoclasts, but both factors are dispensable for giant cell formation by macrophages. Because PU.1 and NF-κB are recruited to the dc-stamp promoter after stimulation with GM-CSF + IL-4, dc-stamp transcription is regulated in a cell type–specific manner.

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