Targeted Expression of Calcitonin Gene-Related Peptide to Osteoblasts Increases Bone Density in Mice

Authors

  • Rabia Ballica,

    1. Yale University School of Medicine, Department of Orthopaedics and Rehabilitation, New Haven, Connecticut, U.S.A.
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  • Karine Valentijn,

    1. Yale University School of Medicine, Department of Orthopaedics and Rehabilitation, New Haven, Connecticut, U.S.A.
    2. Yale University School of Medicine, Department of Cell Biology, New Haven, Connecticut, U.S.A.
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  • Armen Khachatryan,

    1. Yale University School of Medicine, Department of Orthopaedics and Rehabilitation, New Haven, Connecticut, U.S.A.
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  • Sylvie Guerder,

    1. Yale University School of Medicine, Department of Immunobiology, New Haven, Connecticut, U.S.A.
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  • Shanta Kapadia,

    1. Yale University School of Medicine, Department of Neurosurgery, New Haven, Connecticut, U.S.A.
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  • Caren Gundberg,

    1. Yale University School of Medicine, Department of Orthopaedics and Rehabilitation, New Haven, Connecticut, U.S.A.
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  • James Gilligan,

    1. Unigene Laboratories, Inc., Fairfield, New Jersey, U.S.A.
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  • Richard A. Flavell,

    1. Yale University School of Medicine, Department of Immunobiology, New Haven, Connecticut, U.S.A.
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  • Agnès Vignery D.D.S., Ph.D.

    Corresponding author
    1. Yale University School of Medicine, Department of Orthopaedics and Rehabilitation, New Haven, Connecticut, U.S.A.
    2. Yale University School of Medicine, Department of Cell Biology, New Haven, Connecticut, U.S.A.
    • Yale University School of Medicine, Department of Orthopaedics and Rehabilitation, 333 Cedar Street, New Haven, CT 06510 U.S.A.
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Abstract

The neuropeptide calcitonin gene-related peptide (CGRP) is concentrated in fine sensory nerve endings innervating all tissues, including bone. CGRP inhibits osteoclasts, stimulates insulin-like growth factor I and inhibits tumor necrosis factor alpha production by osteoblasts in vitro. To investigate the role of CGRP in bone in vivo, mice were engineered to express CGRP in osteoblasts by placing the human CGRP gene under the control of the rat osteocalcin promoter (Ost-CGRP tg+ mice). Calvaria cultures from transgene positive (tg+), but not tg− mice, produced bioactive CGRP. Trabecular bone density and bone volume, determined by peripheral quantitative computed tomography and bone histomorphometry, respectively, were higher in tg+ than tg− littermates. This increase in bone volume was associated with an increased bone formation rate. Trabecular bone density decreased in tg+ mice as a result of ovariectomy, but remained higher than in sham tg− mice. Targeting CGRP to osteoblasts appears to favor the establishment of a higher trabecular bone mass in mice.

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