FGF2 stimulation of the pyrophosphate-generating enzyme, PC-1, in pre-osteoblast cells is mediated by RUNX2.
Pyrophosphate is an established inhibitor of hydroxyapatite deposition and crystal growth, yet when hydrolyzed into phosphate, it becomes a substrate for hydroxyapatite deposition. Pyrophosphate-generating enzyme (PC-1), Ank, and tissue nonspecific alkaline phosphatase (Tnap) are three factors that regulate extracellular pyrophosphate levels through its generation, transport, and hydrolysis. We previously showed that fibroblast growth factor 2 (FGF2) induces PC-1 and Ank while inhibiting Tnap expression and mineralization in MC3T3E1(C4) calvarial pre-osteoblast cells. In this study, we showed similar FGF2 regulation of these genes in primary pre-osteoblast cultures. In contrast to Ank and Tnap that are regulated by FGF2 in multiple cell types, we found regulation of PC-1 to be selective to pre-osteoblastic cells and to require the osteoblast-related transcription factor, Runx2. Specifically, FGF2 was unable to induce PC-1 expression in Runx2-negative nonbone cells or in calvarial cells from Runx2-deficient mice. Transfection of these cells with a Runx2 expression vector restored FGF2 responsiveness. FGF2 was also shown to stimulate recruitment of Runx2 to the endogenous PC-1 promoter in MC3T3E1(C4) cells, as measured by chromatin immunoprecipitation. Taken together, our results establish that FGF2 is a specific inducer of PC-1 in pre-osteoblast cells and that FGF2 induces PC-1 expression through a mechanism involving Runx2.
Hatch
Nan E
NE
Department of Orthodontics and Pediatric Dentistry, University of Michigan, Ann Arbor, Michigan 48109-1078, USA. nhatch@umich.edu
Li
Yan
Y
Franceschi
Renny T
RT
D000818:Animals; D001665:Binding Sites; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002352:Carrier Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D009154:Mutation / Q000235:genetics; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D028061:Phosphate Transport Proteins; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D012886:Skull / Q000166:cytology / Q000201:enzymology; D017154:Stromal Cells / Q000187:drug effects / Q000201:enzymology; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects
D002352:Carrier Proteins; D050659:Core Binding Factor Alpha 1 Subunit; D011756:Diphosphates; D008565:Membrane Proteins; D028061:Phosphate Transport Proteins; C410982:ank protein, mouse; D016222:Fibroblast Growth Factor 2; D010727:Phosphoric Diester Hydrolases; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1; D011755:Pyrophosphatases