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Oscillating fluid flow activation of gap junction hemichannels induces atp release from MLO-Y4 osteocytes

Authors

  • Damian C. Genetos,

    1. Department of Orthopaedic Surgery, University of California at Davis, Sacramento, California
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  • Curtis J. Kephart,

    1. Division of Musculoskeletal Sciences, Department of Orthopaedics and Rehabilitation, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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  • Yue Zhang,

    1. Division of Musculoskeletal Sciences, Department of Orthopaedics and Rehabilitation, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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  • Clare E. Yellowley,

    1. Department of Anatomy, Physiology, and Cell Biology, School of Veterinary Medicine, University of California at Davis, Davis, California
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  • Henry J. Donahue

    Corresponding author
    1. Division of Musculoskeletal Sciences, Department of Orthopaedics and Rehabilitation, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
    • Division of Musculoskeletal Sciences, Department of Orthopaedics and Rehabilitation, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033.
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Abstract

Mechanical loads are required for optimal bone mass. One mechanism whereby mechanical loads are transduced into localized cellular signals is strain-induced fluid flow through lacunae and canaliculi of bone. Gap junctions (GJs) between osteocytes and osteoblasts provides a mechanism whereby flow-induced signals are detected by osteocytes and transduced to osteoblasts. We have demonstrated the importance of GJ and gap junctional intercellular communication (GJIC) in intracellular calcium and prostaglandin E2 (PGE2) increases in response to flow. Unapposed connexons, or hemichannels, are themselves functional and may constitute a novel mechanotransduction mechanism. Using MC3T3-E1 osteoblasts and MLO-Y4 osteocytes, we examined the time course and mechanism of hemichannel activation in response to fluid flow, the composition of the hemichannels, and the role of hemichannels in flow-induced ATP release. We demonstrate that fluid flow activates hemichannels in MLO-Y4, but not MC3T3-E1, through a mechanism involving protein kinase C, which induces ATP and PGE2 release.. J. Cell. Physiol. 212: 207–214, 2007. © 2007 Wiley-Liss, Inc.

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