title: Calcium-mediated increased expression of fibroblast growth factor-2 acts through NF-κB and PGE2/EP4 receptor signaling pathways in cementoblasts.
abstract: We reported previously that cementoblasts are provided with sensing mechanisms for extracellular Ca2+ and that elevated extracellular Ca2+ increases fibroblast growth factor-2 (FGF-2) gene and protein expression levels via a cyclic AMP/protein kinase A (PKA) dependent pathway. In the present study, we found that stimulation of murine cementoblasts with 10 mM CaCl2 induced cyclooxygenase-2 (COX-2) gene expression and prostaglandin E2 (PGE2) biosynthesis. NS-398, a COX-2 inhibitor, significantly reduced CaCl2-induced increase in Fgf-2 gene expression, indicating that PGE2 synthesized by COX-2 may be involved in FGF-2 induction. The inhibitory effect of NS-398 was restored completely by the addition of PGE2 receptor 4 (E-prostanoid receptor 4, called EP4) agonist, but not agonists for EP1, EP2, and EP3. Furthermore, EP4 antagonist significantly reduced CaCl2-induced Fgf-2 induction, suggesting that it is mediated by EP4 activation. However, stimulation with EP4 agonist alone in the absence of CaCl2 had no effect on the Fgf-2 induction, indicating that EP4 signaling alone is not sufficient. CaCl2 also upregulated gene expression levels of Ep4 and Cox-2, as well as Fgf-2 and induction of these genes was abolished by pretreatment with BMS-345541, a nuclear factor-κB (NF-κB) inhibitor, indicating that NF-κB signaling triggered by CaCl2 is indispensable for FGF-2 induction. Furthermore, CaCl2-induced Fgf-2 induction was synergistically enhanced by the addition of EP4 agonist. This indicates that the signaling triggered via CaCl2 and its combination with EP4 agonist may be useful as a novel strategy for periodontal regeneration.
authors.affiliation: Department of Periodontology and Endodontology, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.
authors.forename: Sousuke
authors.initials: S
authors.lastname: Kanaya
authors.forename: Eiji
authors.initials: E
authors.lastname: Nemoto
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Sakisaka
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Shimauchi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology*; D002460:Cell Line; D003739:Dental Cementum / Q000187:drug effects* / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D016328:NF-kappa B; D058309:Receptors, Prostaglandin E, EP4 Subtype; D016222:Fibroblast Growth Factor 2; D002118:Calcium
keywords: COX-2; Cementoblast; Extracellular Ca(2+); FGF-2; PGE(2)