Osteoblast-specific Angiopoietin 1 overexpression increases bone mass

Toru Suzuki, Takeshi Miyamoto, Nobuyuki Fujita, Ken Ninomiya, Ryotaro Iwasaki, Yoshiaki Toyama, Toshio Suda

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Although osteoblasts express the angiogenic protein Angiopoietin 1 (Ang1), the role of Ang1 in bone formation remains largely unknown. Here we report that Ang1 overexpression in osteoblasts driven by the osteoblast-specific 2.3 kb alpha 1 type 1 collagen promoter results in increased bone mass in vivo. In Ang1-transgenic mice (Ang1-Tg), bone volume and bone parameters increased significantly compared with wild-type littermates, although the Ang1 receptor, Tie2 was not expressed in osteoblasts. Tie2 is primarily expressed in vascular endothelial cells, and Ang1-Tie2 signaling is reportedly crucial for angiogenesis. We found that the number of vascular endothelial cells was significantly elevated in Ang1-Tg mice compared with that of wild-type littermates, an increase accompanied by increased alkaline-phosphatase activity, a marker of osteoblast activation. The number of osteoclasts in the bone of Ang1-Tg mice did not differ from wild-type littermates. These results indicate that angiogenesis induced by Ang1 expressed in osteoblasts is coupled with osteogenesis.

Original languageEnglish
Pages (from-to)1019-1025
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume362
Issue number4
DOIs
Publication statusPublished - 03-11-2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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