Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8347867 | Peptides | 2015 | 7 Pages |
Abstract
BMP induces osteoblast differentiation, whereas a key proinflammatory cytokine, TNF-α, causes inflammatory bone damage shown in rheumatoid arthritis. FGF molecules are known to be involved in bone homeostasis. However, the effects of FGF-8 on osteoblast differentiation and the interaction between FGF-8, BMPs and TNF-α have yet to be clarified. Here we investigated the effects of FGF-8 in relation to TNF-α actions on BMP-2-induced osteoblast marker expression using myoblast cell line C2C12, osteoblast precursor cell line MC3T3-E1 and rat calvarial osteoblasts. It was revealed that FGF-8 inhibited BMP-2-induced expression of osteoblast differentiation markers, including Runx2, osteocalcin, alkaline phosphatase, type-1 collagen and osterix, in a concentration-dependent manner. The inhibitory effects of FGF-8 on BMP-induced osteoblast differentiation and Smad1/5/8 activation were enhanced in the presence of TNF-α action. FGF-8 also inhibited BMP-2-induced expression of Wnt5a, which activates a non-canonical Wnt signaling pathway. FGF-8 had no significant influence on the expression levels of TNF receptors, while FGF-8 suppressed the expression of inhibitory Smad6 and Smad7, suggesting a possible feedback activity through FGF to BMP receptor (BMPR) signaling. Of note, inhibition of ERK activity and FGF receptor (FGFR)-dependent protein kinase, but not JNK or NFκB pathway, suppressed the FGF-8 actions on BMP-induced osteoblast differentiation. FGF-8 was revealed to suppress BMP-induced osteoblast differentiation through the ERK pathway and the effects were enhanced by TNF-α. Given the finding that FGF-8 expression was increased in synovial tissues of rheumatoid arthritis, the functional interaction between FGFR and BMPR signaling may be involved in the development process of inflammatory bone damage.
Keywords
ActRIIFGFRBMPRIITGF-βTNFTNFRactivin type-II receptorRUNX2BMP type-II receptorreceptor activator of NFκBFGFERKMAPKSAPK/JNKRheumatoid arthritisALKALPAlkaline phosphataseOsteoarthritisOsteoblastOsteogenesistransforming growth factor-βRankRunt-related transcription factor 2Tumor necrosis factor (TNF)-αfibroblast growth factortumor necrosis factorBMPBone morphogenetic proteinbone morphogenetic protein (BMP)mitogen-activated protein kinaseextracellular signal-regulated kinaseactivin receptor-like kinaseFGF ReceptorTNF receptor
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Authors
Takayuki Katsuyama, Fumio Otsuka, Tomohiro Terasaka, Kenichi Inagaki, Mariko Takano-Narazaki, Yoshinori Matsumoto, Ken-Ei Sada, Hirofumi Makino,