Analysis of differential gene expression in rat tibia after an osteogenic stimulus in vivo: Mechanical loading regulates osteopontin and myeloperoxidase

Rebecca R. Miles, Charles H. Turner, Robert Santerre, Yuan Tu, Pam McClelland, Jeanne Argot, Bradley S. DeHoff, Christopher W. Mundy, Paul R. Rosteck, Joseph Bidwell, James P. Sluka, Janet Hock, Jude E. Onyia

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31 Scopus citations


The skeleton has the ability to alter its mass, geometry, and strength in response to mechanical stress. In order to elucidate the molecular mechanisms underlying this phenomenon, differential display reverse transcriptasepolymerase chain reaction (DDRT-PCR) was used to analyze gene expression in endocortical bone of mature female rats. Female Sprague-Dawley rats, approximately 8 months old, received either a sham or bending load using a four-point loading apparatus on the right tibia. RNA was collected at 1 h and 24 h after load was applied, reverse-transcribed into cDNA, and used in DDRT-PCR. Parallel display of samples from sham and loaded bones on a sequencing gel showed several regulated bands. Further analysis of seven of these bands allowed us to isolate two genes that are regulated in response to a loading stimulus. Nucleotide analysis showed that one of the differentially expressed bands shares 99% sequence identity with rat osteopontin (OPN), a noncollagenous bone matrix protein. Northern blot analysis confirms that OPN mRNA expression is increased by nearly 4-fold, at 6 h and 24 h after loading. The second band shares 90% homology with mouse myeloperoxidase (MPO), a bactericidal enzyme found primarily in neutrophils and monocytes. Semiquantitative PCR confirms that MPO expression is decreased 4- to 10- fold, at 1 h and 24 h after loading. Tissue distribution analysis confirmed MPO expression in bone but not in other tissues examined. In vitro analysis showed that MPO expression was not detectable in total RNA from UMR 106 osteoblastic cells or in confluent primary cultures of osteoblasts derived from either rat primary spongiosa or diaphyseal marrow. Database analysis suggests that MPO is expressed by osteocytes. These findings reinforce the association of OPN expression to bone turnover and describes for the first time, decreased expression of MPO during load-induced bone formation. These results suggest a role for both OPN and MPO expression in bone cell function.

Original languageEnglish (US)
Pages (from-to)355-365
Number of pages11
JournalJournal of Cellular Biochemistry
Issue number3
StatePublished - Mar 1 1998


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Miles, R. R., Turner, C. H., Santerre, R., Tu, Y., McClelland, P., Argot, J., DeHoff, B. S., Mundy, C. W., Rosteck, P. R., Bidwell, J., Sluka, J. P., Hock, J., & Onyia, J. E. (1998). Analysis of differential gene expression in rat tibia after an osteogenic stimulus in vivo: Mechanical loading regulates osteopontin and myeloperoxidase. Journal of Cellular Biochemistry, 68(3), 355-365.<355::AID-JCB6>3.0.CO;2-T