Fibroblast growth factor 2 and cyclic AMP synergistically regulate bone sialoprotein gene expression.
Bone sialoprotein (BSP) is a noncollagenous protein of the mineralized bone extracellular matrix. We here report that FGF2 and cAMP act synergistically to stimulate BSP gene expression. Treatment of ROS 17/2.8 cells with either 10 ng/ml FGF2 or 1 microM FSK for 6 h resulted in 5.4- and 8.2-fold increases, respectively, in the levels of BSP mRNA. However, in the presence of both FGF2 and forskolin (FGF/FSK), BSP mRNA levels were increased synergistically by 20.4-fold. Using a luciferase reporter construct, encompassing BSP promoter nucleotides -116 to +60, transcription was also increased synergistically by 15.0-fold with FGF/FSK, compared to stimulations of 2.6- and 5.3-fold, respectively, for FGF2 and FSK alone. Transcriptional stimulation by FGF/FSK abrogated in constructs included 2 bp mutations in the inverted CCAAT, CRE, FRE and Pit-1 elements. Whereas the FRE-protein complex was increased by FGF2 and FGF/FSK, the Pit-1-protein complex was decreased by FSK and FGF/FSK. Notably, transcriptional activity induced by FGF/FSK was blocked by protein kinase A, tyrosine kinase and MEK inhibitors. These studies indicate that the combinatorial effects of FGF and FSK act through PKA, tyrosine kinase and MAP-kinase-dependent pathways, which target the inverted CCAAT, CRE, FRE and Pit-1 elements in the BSP gene to synergistically increase BSP expression.
Shimizu
Emi
E
Department of Periodontology, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan.
Nakayama
Youhei
Y
Nakajima
Yu
Y
Kato
Naoko
N
Takai
Hideki
H
Kim
Dong-Soon
DS
Arai
Masato
M
Saito
Ryoichiro
R
Sodek
Jaro
J
Ogata
Yorimasa
Y
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D002999:Clone Cells; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000494:pharmacology; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D017930:Genes, Reporter; D058574:Integrin-Binding Sialoprotein; D008156:Luciferases / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism*; D017154:Stromal Cells / Q000166:cytology*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects
D002070:Butadienes; D004791:Enzyme Inhibitors; D058574:Integrin-Binding Sialoprotein; D009570:Nitriles; D012333:RNA, Messenger; D012795:Sialoglycoproteins; C113580:U 0126; D016222:Fibroblast Growth Factor 2; D005576:Colforsin; D000242:Cyclic AMP; D008156:Luciferases; D017868:Cyclic AMP-Dependent Protein Kinases