Fibroblast growth factor-2 induces osteogenic differentiation through a Runx2 activation in vascular smooth muscle cells.
Expression of bone-associated proteins and osteoblastic transcription factor Runx2 in arterial cells has been implicated in the development of vascular calcification. However, the signaling upstream of the Runx2-mediated activation of osteoblastic program in vascular smooth muscle cells (VSMC) is poorly understood. We examined the effects of fibroblast growth factor-2 (FGF-2), an important regulator of bone formation, on osteoblastic differentiation of VSMC. Stimulation of cultured rat aortic SMC (RASMC) with FGF-2 induced the expression of the osteoblastic markers osteopontin (OPN) and osteocalcin. Luciferase assays showed that FGF-2 induced osteocyte-specific element (OSE)-dependent transcription. Downregulation of Runx2 by siRNA repressed the basal and FGF-2-stimulated expression of the OPN gene in RASMC. FGF-2 produced hydrogen peroxide in RASMC, as evaluated by fluorescent probe. Induction of OPN expression by FGF-2 was inhibited not only by PD98059 (MEK1 inhibitor) and PP1 (c-Src inhibitor), but also by an antioxidant, N-acetyl cysteine. Nuclear extracts from FGF-2-treated RASMC exhibited increased DNA-binding of Runx2 to its target sequence. Immunohistochemistry of human coronary atherectomy specimens and calcified aortic tissues showed that expression of FGF receptor-1 and Runx2 was colocalized. In conclusion, these results suggest that FGF-2 plays a role in inducing osteoblastic differentiation of VSMC by activating Runx2 through mitogen-activated protein kinase (MAPK)-dependent- and oxidative stress-sensitive-signaling pathways.
Nakahara
Takehiro
T
Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma 371-8511, Japan.
Sato
Hiroko
H
Shimizu
Takehisa
T
Tanaka
Toru
T
Matsui
Hiroki
H
Kawai-Kowase
Keiko
K
Sato
Mahito
M
Iso
Tatsuya
T
Arai
Masashi
M
Kurabayashi
Masahiko
M
D000818:Animals; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism; D000081247:CSK Tyrosine-Protein Kinase; D002454:Cell Differentiation; D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology / Q000502:physiology*; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D005819:Genetic Markers; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism*; D010012:Osteogenesis; D053495:Osteopontin / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism; D015533:Transcriptional Activation; D019061:src-Family Kinases
D050659:Core Binding Factor Alpha 1 Subunit; D005819:Genetic Markers; D016222:Fibroblast Growth Factor 2; D053495:Osteopontin; D006861:Hydrogen Peroxide; C496348:FGFR1 protein, human; D011505:Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D020929:Mitogen-Activated Protein Kinase Kinases