Chemerin neutralization blocks hematopoietic stem cell osteoclastogenesis

Authors

  • Shanmugam Muruganandan,

    1. Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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  • Helen J. Dranse,

    1. Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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  • Jillian L. Rourke,

    1. Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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  • Nichole M. McMullen,

    1. Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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  • Christopher J. Sinal

    Corresponding author
    1. Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
    • Correspondence: Christopher J. Sinal, Ph.D., Department of Pharmacology, Dalhousie University, 5850 College Street, Box 15000, Halifax, Nova Scotia, Canada B3H4R2. Telephone: 902-494-2347; e-mail: csinal@dal.ca

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  • Author contributions: S.M., H.D., and J.R.: conception and design, collection and/or assembly of data, data analysis and interpretation, manuscript writing, and final approval of manuscript; N.M.: collection and/or assembly of data, data analysis and interpretation, and final approval of manuscript; C.S.: conception and design, data analysis and interpretation, manuscript writing, and final approval of manuscript.

ABSTRACT

Bone is a dynamic tissue that is continuously remodeled through the action of formative osteoblasts and resorptive osteoclasts. Chemerin is a secreted protein that activates chemokine-like receptor 1 (CMKLR1), a G protein-coupled receptor expressed by various cell types including adipocytes, osteoblasts, mesenchymal stem cells (MSCs), and macrophages. Previously, we identified chemerin as a regulator of adipocyte and osteoblast differentiation of MSCs. Herein we examined the role of chemerin in Lin Sca1+ c-kit+ CD34+ hematopoietic stem cell (HSC) osteoclastogenesis. We found that HSCs expressed both chemerin and CMKLR1 mRNA and secreted chemerin protein into the extracellular media. Neutralization of chemerin with a blocking antibody beginning prior to inducing osteoclast differentiation resulted in a near complete loss of osteoclastogenesis as evidenced by reduced marker gene expression and matrix resorption. This effect was conserved in an independent model of RAW264.7 cell osteoclastogenesis. Reintroduction of chemerin by reversal of neutralization rescued osteoclast differentiation indicating that chemerin signaling is essential to permit HSC differentiation into osteoclasts but following blockade the cells maintained the potential to differentiate into osteoclasts. Mechanistically, neutralization of chemerin blunted the early receptor activator of nuclear factor-kappa B ligand induction of nuclear factor of activated T-cells 2 (NFAT2), Fos, Itgb3, and Src associated with preosteoclast formation. Consistent with a central role for NFAT2, induction or activation of NFAT2 by forced expression or stimulation of intracellular calcium release rescued the impairment of HSC osteoclastogenesis caused by chemerin neutralization. Taken together, these data support a novel autocrine/paracrine role for chemerin in regulating osteoclast differentiation of HSCs through modulating intracellular calcium and NFAT2 expression/activation. Stem Cells 2013;31:2172–2182

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