title: Prostaglandins differently regulate FGF-2 and FGF receptor expression and induce nuclear translocation in osteoblasts via MAPK kinase.
abstract: We have previously reported that prostaglandin F(2alpha) (PGF(2alpha)) and its selective agonist fluprostenol increase basic fibroblast growth factor (FGF-2) mRNA and protein production in osteoblastic Py1a cells. The present report extends our previous studies by showing that Py1a cells express FGF receptor-2 (FGFR2) and that treatment with PGF(2alpha) or fluprostenol decreases FGFR2 mRNA. We have used confocal and electron microscopy to show that, under PGF(2alpha) stimulation, FGF-2 and FGFR2 proteins accumulate near the nuclear envelope and colocalize in the nucleus of Py1a cells. Pre-treatment with cycloheximide blocks nuclear labelling for FGF-2 in response to PGF(2alpha). Treatment with SU5402 does not block prostaglandin-mediated nuclear internalization of FGF-2 or FGFR2. Various effectors have been used to investigate the signal transduction pathway. In particular, pre-treatment with phorbol 12-myristate 13-acetate (PMA) prevents the nuclear accumulation of FGF-2 and FGFR2 in response to PGF(2alpha). Similar results are obtained by pre-treatment with the protein kinase C (PKC) inhibitor H-7. In addition, cells treated with PGF(2alpha) exhibit increased nuclear labelling for the mitogen-activated protein kinase (MAPK), p44/ERK2. Pre-treatment with PMA blocks prostaglandin-induced ERK2 nuclear labelling, as confirmed by Western blot analysis. We conclude that PGF(2alpha) stimulates nuclear translocation of FGF-2 and FGFR2 by a PKC-dependent pathway; we also suggest an involvement of MAPK/ERK2 in this process.
authors.affiliation: Department of Comparative Morphology and Biochemistry, Via Gentile III da Varano, 62032 Camerino (MC), Italy. giovanna.sabbieti@unicam.it
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Sabbieti
authors.forename: Luigi
authors.initials: L
authors.lastname: Marchetti
authors.forename: Maria Gabriella
authors.initials: MG
authors.lastname: Gabrielli
authors.forename: Maura
authors.initials: M
authors.lastname: Menghi
authors.forename: Stefano
authors.initials: S
authors.lastname: Materazzi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Menghi
authors.forename: Lawrence G
authors.initials: LG
authors.lastname: Raisz
authors.forename: Marja M
authors.initials: MM
authors.lastname: Hurley
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002461:Cell Line, Transformed; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D015237:Dinoprost / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation / Q000187:drug effects*; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D016253:Microscopy, Immunoelectron; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009685:Nuclear Envelope / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D010006:Osteoblasts / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D011453:Prostaglandins / Q000494:pharmacology*; D011461:Prostaglandins F, Synthetic / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D051497:Receptor, Fibroblast Growth Factor, Type 2; D017468:Receptors, Fibroblast Growth Factor / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D011453:Prostaglandins; D011461:Prostaglandins F, Synthetic; D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; D016222:Fibroblast Growth Factor 2; C006326:fluprostenol; D015237:Dinoprost; C496356:Fgfr2 protein, rat; D020794:Receptor Protein-Tyrosine Kinases; D051497:Receptor, Fibroblast Growth Factor, Type 2; D048052:Mitogen-Activated Protein Kinase 3