Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation.
We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P receptor-mediated signaling plays a crucial role for osteoblast differentiation.
Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501, Japan.
Chieri
C
Sato
Tsuyoshi
T
Iwasaki
Sachie
S
Kitano
Sachi
S
Tsunemi
Hajime
H
Sano
D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis; D000068876:Fingolimod Hydrochloride; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D010006:Osteoblasts / Q000166:cytology*; D015675:Osteocalcin / Q000378:metabolism; D011409:Propylene Glycols / Q000494:pharmacology; D049349:Receptors, Lysosphingolipid / Q000819:agonists* / Q000378:metabolism; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology
D055396:Bone Morphogenetic Protein 2; D050659:Core Binding Factor Alpha 1 Subunit; D008246:Lysophospholipids; D011409:Propylene Glycols; D049349:Receptors, Lysosphingolipid; C493716:Runx2 protein, mouse; D051785:Smad Proteins; D015675:Osteocalcin; C060506:sphingosine 1-phosphate; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine