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Antisense oligodeoxynucleotide evidence that a unique osteoclastic protein-tyrosine phosphatase is essential for
S M Suhr1, S Pamula, D J Baylink
1Department of Medicine and Biochemistry, Loma Linda University and J L. Pettis Memorial VAMC, California 92357, USA.
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 microM 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 microM 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.
Insights
This study demonstrates that suppressing PTP-oc protein expression using an antisense oligodeoxynucleotide inhibits osteoclastic resorption. This finding highlights PTP-oc
Area of Science:
- Biochemistry
- Cell Biology
- Bone Metabolism
Background:
- Osteoclastic resorption is a critical process in bone remodeling.
- The molecular mechanisms regulating osteoclast activity are not fully understood.
- Protein tyrosine phosphatases (PTPs) are implicated in cellular signaling pathways.
Purpose of the Study:
- To investigate the role of a specific osteoclastic transmembrane protein tyrosine phosphatase (PTP-oc) in osteoclastic resorption.
- To determine if suppressing PTP-oc expression inhibits basal, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-stimulated, and parathyroid hormone (PTH)-stimulated osteoclastic resorption.
Main Methods:
- Treatment of rabbit osteoclasts with a PTP-oc antisense oligodeoxynucleotide (oligo).
- Assessment of PTP-oc protein levels via Western blot.
- Measurement of osteoclastic resorptive activity using a pit formation assay.
- Analysis of c-src phosphorylation.
Main Results:
- The PTP-oc antisense oligo effectively reduced PTP-oc protein levels in a time-dependent manner.
- Antisense oligo treatment significantly inhibited basal, 1,25(OH)2D3-stimulated, and PTH-stimulated osteoclastic resorption.
- PTP-oc suppression led to increased Y527 phosphorylation of c-src.
Conclusions:
- PTP-oc plays an essential role in osteoclastic resorption.
- Targeting PTP-oc with antisense oligonucleotides offers a potential strategy to modulate bone resorption.