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Rho-kinase limits FGF-2-stimulated VEGF release in osteoblasts

Hideo Natsume1, Haruhiko Tokuda, Seiji Adachi

  • 1Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.

Bone
|February 2, 2010
PubMed

Insights

Rho-kinase negatively regulates vascular endothelial growth factor (VEGF) release stimulated by basic fibroblast growth factor (FGF-2) in osteoblasts. Inhibiting Rho-kinase enhances FGF-2-induced VEGF release and strengthens SAPK/JNK phosphorylation.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Basic fibroblast growth factor (FGF-2) influences osteoblast function.
  • FGF-2 signaling involves mitogen-activated protein kinases (MAPKs) and regulates vascular endothelial growth factor (VEGF) release.
  • Previous studies indicated complex regulation of VEGF release by different MAPK pathways in osteoblasts.

Purpose of the Study:

  • To investigate the role of Rho-kinase in the regulation of FGF-2-stimulated VEGF release in osteoblast-like MC3T3-E1 cells.
  • To determine the signaling pathways affected by Rho-kinase inhibition in response to FGF-2.

Main Methods:

  • Utilized MC3T3-E1 cells and primary human osteoblasts.
  • Administered FGF-2 and specific Rho-kinase inhibitors (Y27632, Fasudil).
  • Assessed VEGF release, VEGF accumulation in cell lysates, and phosphorylation of key signaling proteins (MYPT-1, p44/p42 MAPK, p38 MAPK, SAPK/JNK).

Main Results:

  • FGF-2 induced Rho-kinase activity, evidenced by MYPT-1 phosphorylation.
  • Inhibition of Rho-kinase by Y27632 and Fasudil significantly enhanced FGF-2-stimulated VEGF release and accumulation.
  • Rho-kinase inhibition did not affect p44/p42 or p38 MAPK phosphorylation but markedly strengthened FGF-2-induced SAPK/JNK phosphorylation.
  • These findings were consistent in both MC3T3-E1 cells and human osteoblasts.

Conclusions:

  • Rho-kinase acts as a negative regulator of FGF-2-stimulated VEGF release in osteoblasts.
  • The inhibitory effect of Rho-kinase on VEGF release is mediated, at least in part, through modulation of the SAPK/JNK signaling pathway.

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