Antisense Oligodeoxynucleotide Evidence That a Unique Osteoclastic Protein-Tyrosine Phosphatase Is Essential for Osteoclastic Resorption

Authors

  • Sung Min Suhr,

    1. Department of Medicine and Biochemistry, Loma Linda University and J. L. Pettis Memorial VAMC, Loma Linda, California, USA
    Search for more papers by this author
  • Sujatha Pamula,

    1. Department of Medicine and Biochemistry, Loma Linda University and J. L. Pettis Memorial VAMC, Loma Linda, California, USA
    Search for more papers by this author
  • David J. Baylink,

    1. Department of Medicine and Biochemistry, Loma Linda University and J. L. Pettis Memorial VAMC, Loma Linda, California, USA
    Search for more papers by this author
  • K.-H. William Lau

    Corresponding author
    1. Department of Medicine and Biochemistry, Loma Linda University and J. L. Pettis Memorial VAMC, Loma Linda, California, USA
    • Address reprint requests to: K.-H. William Lau, Ph.D., Musculoskeletal Disease Center (151), Jerry L. Pettis Memorial VA Medical Center, 11201 Benton Street, Loma Linda, CA 92357, USA
    Search for more papers by this author

Abstract

This study tested the hypothesis that a unique osteoclastic transmembrane protein tyrosine phosphatase (PTP-oc) is involved in osteoclastic resorption by determining whether suppression of PTP-oc expression with a specific phosphorothioated 20-mer PTP-oc antisense oligodeoxynucleotide (oligo) would inhibit basal, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-stimulated, and PTH-stimulated osteoclastic resorption. Treatment of rabbit osteoclasts with 1 μM of the antisense oligo for up to 4 days showed a time-dependent reduction in PTP-oc protein level, indicating that this PTP-oc antisense oligo was effective. To assess the effect of PTP-oc antisense oligo on osteoclastic resorption, rabbit osteoclasts were pretreated for 3 days with 1 μM of the antisense, a scramble oligo, or vehicle, respectively, followed by a 3-day treatment with vehicle, 10 nM of 1,25(OH)2D3, or 10 nM of parathyroid hormone (PTH). 1,25(OH)2D3 and PTH each alone increased PTP-oc cellular level and stimulated resorptive activity of rabbit osteoclasts. The antisense oligo treatment, but not the scramble oligo, decreased the basal and the stimulated resorption activity and reduced the PTP-oc protein level. Treatment with the PTP-oc antisense oligo, but not the scramble oligo, also markedly increased the Y527 phosphorylation level of c-src in rabbit osteoclasts. In conclusion, these results provide the first antisense oligo evidence that PTP-oc plays an essential role in osteoclastic resorption.

Ancillary