title: Fibroblast growth factor-2 (FGF-2) increases N-cadherin expression through protein kinase C and Src-kinase pathways in human calvaria osteoblasts.
abstract: Fibroblast growth factors (FGFs) are important factors regulating osteogenesis. However, the early mechanisms and signaling pathways involved in FGF actions in osteoblasts are unknown. We investigated the effects of FGF-2 on cell-cell adhesion and cadherin expression and the underlying signaling pathways in immortalized human neonatal calvaria (IHNC) cells. These cells express E- and N-cadherins, as shown by immunocytochemical and Western blot analyses. rhFGF-2 increased cell-cell adhesion at 24-72 h, as measured in a cell aggregation assay, and this effect was blocked by specific neutralizing anti-N-cadherin, but not anti-E-cadherin antibodies. Accordingly, ELISA and Western blot analyses showed that rhFGF-2 (10-100 ng/ml) dose dependently increased N-cadherin but not E-cadherin protein levels. RT-PCR analysis showed that rhFGF-2 transiently increased N-cadherin mRNA levels in IHNC cells. The RNA polymerase II inhibitor 5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole prevented the rhFGF-2-induced up-regulation of N-cadherin mRNA, suggesting that transcription is necessary for this effect. Analysis of signaling molecules showed evidence that PLCgamma-PKC, Src, Erk 1/2 and p38 MAPK pathways are activated by rhFGF-2 in IHNC cells. The selective PKC inhibitors calphostin C, Ro-31-8220, Gö6976 and Gö6983 abrogated the stimulatory effect of rhFGF-2 on N-cadherin mRNA levels. The src-family tyrosine kinase inhibitor PP1 also blocked rhFGF-2-promoted N-cadherin expression. In contrast, the p38 MAP kinase inhibitor SB 203580 or the MEK inhibitor PD98059 had no effect on rhFGF-2-induced N-cadherin mRNA levels. Our data indicate that FGF-2 increases N-cadherin expression and function in human calvaria osteoblasts via activation of PKC and src-kinase pathways. This study identifies N-cadherin as a previously unrecognized target gene for FGF-2 signaling pathway that regulates cell-cell adhesion in human osteoblasts.
authors.affiliation: INSERM Unit 349 Affiliated CNRS, Lariboisiere Hospital, 2 rue Ambroise Paré, 75475 Paris Cedex 10, France.
authors.forename: F
authors.initials: F
authors.lastname: Debiais
authors.forename: J
authors.initials: J
authors.lastname: Lemonnier
authors.forename: E
authors.initials: E
authors.lastname: Hay
authors.forename: P
authors.initials: P
authors.lastname: Delannoy
authors.forename: J
authors.initials: J
authors.lastname: Caverzasio
authors.forename: P J
authors.initials: PJ
authors.lastname: Marie
mesh_terms: D015820:Cadherins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D004789:Enzyme Activation; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D015151:Immunoblotting; D010006:Osteoblasts / Q000201:enzymology / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D015820:Cadherins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D019061:src-Family Kinases; D011493:Protein Kinase C