Caveolae in Human and Murine Osteoblasts

Authors

  • Keith R. Solomon,

    Corresponding author
    1. Department of Orthopedic Surgery, Children's Hospital, Boston, Massachusetts, U.S.A.
    2. Harvard Medical School, Boston, Massachusetts, U.S.A.
    • Address reprint requests to: Keith R. Solomon, Ph.D., Department of Orthopedic Surgery, Enders 1106, Children's Hospital, Boston, MA 02115, U.S.A.
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  • Layla D. Adolphson,

    1. Department of Orthopedic Surgery, Children's Hospital, Boston, Massachusetts, U.S.A.
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  • David A. Wank,

    1. Department of Orthopedic Surgery, Children's Hospital, Boston, Massachusetts, U.S.A.
    2. Harvard School of Dental Medicine, Boston, Massachusetts, U.S.A.
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  • Kevin P. Mchugh,

    1. Department of Orthopedic Surgery, Children's Hospital, Boston, Massachusetts, U.S.A.
    2. Harvard Medical School, Boston, Massachusetts, U.S.A.
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  • Peter V. Hauschka


Abstract

Caveolae are 50- to 100-nm plasmalemmal vesicles formed by oligomerized caveolin, a 22-kDa phosphoprotein. These organelles have been implicated in critical signal transduction and molecular transport processes. Here, we show for the first time that osteoblasts express caveolin and have abundant caveolae. Membrane fractionation techniques indicate that osteoblast caveolin is found in detergent-resistant membranes that have the buoyant density characteristic of caveolae, whereas immunoblotting and reverse-transcription polymerase chain reaction (RT-PCR) show that osteoblasts express both caveolin-1 and −2 isoforms. Electron microscopy (EM) and immunofluorescence reveal the hallmarks of caveolae in osteoblasts: abundant 50- to 100-nm noncoated cell surface invaginations (caveolae) and abundant punctate clusters of immunostained caveolin.

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