Transcriptional Activity of Nuclei in Multinucleated Osteoclasts and Its Modulation by Calcitonin

Boissy, Patrice; Saltel, Frédéric; Bouniol, Christine; Jurdic, Pierre; Machuca-Gayet, Irma

doi:10.1210/endo.143.5.8813

Cited by 62 publications

(29 citation statements)

References 27 publications

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“…Interestingly, DAP12 was recently demonstrated to be one of three genes upregulated by the PU.1 transcription factor, which has previously been shown to be essential for osteoclast development. (28) Osteoclast function has been previously correlated with the degree of multinucleation (29) ; therefore, we were unable to determine if DAP12 plays a direct role in promoting the resorptive function of osteoclasts or whether it is the effect on development of multinuclear osteoclasts that indirectly affects the capacity for bone resorption.…”

Section: Discussionmentioning

confidence: 99%

The Signaling Adapter Protein DAP12 Regulates Multinucleation During Osteoclast Development

Humphrey

Ogasawara

Yao

et al. 2004

Journal of Bone and Mineral Research

107

125

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Deficiency of the signaling adapter protein DAP12 is associated with bony abnormalities in both mice and humans. We identify specific DAP12-associated receptors expressed by osteoclasts and examine function of DAP12 in murine osteoclasts in vivo and in vitro. These data show a new role for DAP12 signaling in regulating formation of multinucleated osteoclasts.Introduction: Osteoclasts are bone-resorbing cells derived from hematopoietic precursors in the myeloid lineage. In other myeloid cell types, the signaling adapter protein DAP12 transmits activating signals on ligation of a DAP12-associated receptor (DAR). The aim of this study was to clarify the role of DAP12 signaling during osteoclast development. Materials and Methods: Osteoclasts from DAP12Ϫ/Ϫ or control mice were analyzed in vitro for morphology, function, and for osteoclast markers. DARs were identified in osteoclast cultures through reverse transcriptase-polymerase chain reaction (RT-PCR). Bone density of DAP12 Ϫ/Ϫ and control mice were analyzed by microcomputed tomography. DAP12Ϫ/Ϫ osteoclasts were retrovirally reconstituted with DAP12. RAW264.7 cells were transfected with FLAG-tagged DAP12 or TREM2 and stimulated by anti-FLAG antibody during in vitro osteoclastogenesis. Results: C57BL/6 DAP12-deficient mice have higher bone mass than C57BL/6 wildtype controls. We verified the presence of DAP12 in pre-osteoclasts and osteoclasts derived from C57BL/6 or the pre-osteoclast line RAW 264.7 and identified the DARs expressed. DAP12Ϫ/Ϫ osteoclasts developed in vitro with macrophage colony-stimulating factor (M-CSF) and RANKL formed only intensely TRACP ϩ mononuclear cells and failed to generate multinuclear osteoclasts. These mononuclear cells are functional osteoclast-like cells because, by RT-PCR, they express other osteoclast markers and generate resorption pits on dentine slices, although quantitative assessment of bone resorption shows decreased resorption by DAP12 Ϫ/Ϫ osteoclasts compared with C57BL/6 osteoclasts. Restoration of DAP12 expression by retroviral transduction of DAP12 Ϫ/Ϫ osteoclast precursors rescued in vitro osteoclast multinucleation. Direct stimulation of DAP12 expressed in RAW264.7 during in vitro osteoclastogenesis led to a marked increase in the number of TRACP

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Section: Discussionmentioning

confidence: 99%

The Signaling Adapter Protein DAP12 Regulates Multinucleation During Osteoclast Development

Humphrey

Ogasawara

Yao

et al. 2004

Journal of Bone and Mineral Research

107

125

View full text Add to dashboard Cite

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“…In turn, since the protein synthesis requirements are met through upregulated translation, increase in genome content through cell fusion is not required, and thus mTORC2 fraction decreases. It has been previously demonstrated that all osteoclast nuclei are similarly engaged in transcription, and that transcriptional activity of osteoclast nuclei is strongly upregulated when osteoclasts engage in resorption (Boissy et al, 2002). Our data suggest that genome content and transcriptional output are closely regulated during osteoclast formation as well as osteoclast function.…”

Section: Discussionmentioning

confidence: 99%

Regulation of Osteoclast Growth and Fusion by mTOR/raptor and mTOR/rictor/Akt

Tiedemann

Nihouannen

Fong

et al. 2017

Front. Cell Dev. Biol.

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Osteoclasts are giant bone cells formed by fusion from monocytes and uniquely capable of a complete destruction of mineralized tissues. Previously, we have demonstrated that in energy-rich environment not only osteoclast fusion index (the number of nuclei each osteoclast contains), but also cytoplasm volume per single nucleus was increased. The goal of this study was to investigate the regulation of metabolic sensor mTOR during osteoclast differentiation in energy-rich environment simulated by addition of pyruvate. We have found that in the presence of pyruvate, the proportion of mTOR associated with raptor increased, while mTOR-rictor-mediated Akt phosphorylation decreased. Inhibition of mTOR with rapamycin (10 nM) significantly interfered with all aspects of osteoclastogenesis. However, rapamycin at 1 nM, which preferentially targets mTOR-raptor complex, was only effective in control cultures, while in the presence of pyruvate osteoclast fusion index was successfully increased. Inhibition of Akt drastically reduced osteoclast fusion, however in energy-rich environment, osteoclasts of comparable size were formed through increased cytoplasm growth. These data suggest that mTOR-rictor mediated Akt signaling regulates osteoclast fusion, while mTOR-raptor regulation of protein translation contributes to fusion-independent cytoplasm growth. We demonstrate that depending on the bioenergetics microenvironment osteoclastogenesis can adjust to occur through preferential multinucleation or through cell growth, implying that attaining large cell size is part of the osteoclast differentiation program.

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“…OCs are the only cells known to resorb bone, and OC resorptive capacity is thought to correlate with the number of OC nuclei present in bones. (18) To explore TREM2-DAP12-mediated regulation of OC resorption, we generated mature OCs using RANKL and M-CSF, and we subsequently examined the effect of TREM2 blockade on bone resorption. TREM2 mAb treatment inhibited resorption by OC in vitro.…”

Section: Figmentioning

confidence: 99%

TREM2, a DAP12-Associated Receptor, Regulates Osteoclast Differentiation and Function

Humphrey

Daws

Spusta

et al. 2006

Journal of Bone and Mineral Research

141

146

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Deficiency of the signaling adapter protein DAP12 or its associated receptor TREM2 is associated with abnormal OC development in humans. Here we examine the role of TREM2 in mouse OC development and function, including migration and resorption in vitro. These results provide new evidence that TREM2 regulates OC function independent of its effects on multinucleated OC differentiation.Introduction: TREM2 (triggering receptor expressed in myeloid cells-2) associates with the signaling adapter DAP12 in osteoclasts (OCs). Genetic mutation or deletion of either the TYROBP (DAP12) or TREM2 gene is associated with the human disorder of brain and bone, Nasu-Hakola disease. We and others recently showed the critical requirement for immunoreceptor tyrosine-based activation motif (ITAM) signals through DAP12 and the Fc Receptor ␥ chain (FcR␥) during OC development. Here, we further define the role of TREM2 in OC differentiation and describe a role for TREM2 in OC migration and bone resorption. Materials and Methods:We generated monoclonal anti-mouse TREM2 antibodies (mAb), analyzed preosteoclasts and mature OCs for TREM2 surface expression, and determined the effect of antibody ligation on in vitro OC differentiation, resorption, and migration. TREM2 RNA interference (RNAi) was used to disrupt expression of TREM2 in pre-osteoclasts. Results: Using flow cytometry, our studies reveal that TREM2 is weakly expressed on C57BL/6 bone marrow macrophages (BMMs) and is upregulated during culture with RANKL and macrophage-colony stimulating factor (M-CSF). The expression of TREM2 is unaltered in DAP12-deficient OCs. Using C57BL/6 BMMs or RAW264.7 precursors, anti-TREM2 mAb treatment with RANKL and M-CSF enhances the formation of multinuclear TRACP + OCs compared with control mAb treatment. In contrast, these agents have no effect on DAP12-deficient precursors. Monoclonal Ab blockade of TREM2 on OCs generated from C57BL/6 BMMs results in decreased resorption of artificial calcium-phosphate substrate and dentine. Reduction of TREM2 expression in RAW264.7 cells by RNAi results in loss of OC formation in response to RANKL and M-CSF. Anti-TREM2 cross-linking enhances migration of C57BL/6 OCs and RAW246.7 OCs in response to M-CSF. Conclusions: Our studies indicate that the TREM2 receptor regulates OC multinucleation as well as resorption and migration of mature OCs. Thus, TREM2-DAP12 signals regulate both OC formation and function.

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Transcriptional Activity of Nuclei in Multinucleated Osteoclasts and Its Modulation by Calcitonin

Cited by 62 publications

References 27 publications

The Signaling Adapter Protein DAP12 Regulates Multinucleation During Osteoclast Development

The Signaling Adapter Protein DAP12 Regulates Multinucleation During Osteoclast Development

Regulation of Osteoclast Growth and Fusion by mTOR/raptor and mTOR/rictor/Akt

TREM2, a DAP12-Associated Receptor, Regulates Osteoclast Differentiation and Function

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