Potential role of PC-1 expression and pyrophosphate elaboration in the molecular etiology of the FGFR-associated craniosynostosis syndromes.
BACKGROUND
Fibroblast growth factor/fibroblast growth factor receptor (FGF/FGFR) signaling is associated with the aberrant mineralization phenotype of the craniosynostosis syndromes. One critical aspect of mineralization involves the elaboration and transport of pyrophosphate into the extracellular matrix with subsequent enzymatic hydrolysis into phosphate. We have previously shown that FGF2 up-regulates expression of the pyrophosphate generating enzyme, PC-1, and the pyrophosphate channel, ANK, while down-regulating expression of the pyrophosphate hydrolyzing enzyme, tissue non-specific alkaline phosphatase in pre-osteoblastic, MC3T3E1(C4) cells. These results suggest that FGF/FGFR signaling may affect mineralization via changes in the elaboration and metabolism of pyrophosphate.


OBJECTIVE
We are currently conducting experiments towards a more systematic analysis of PC-1 expression in osteoblastic cells, in order to more clearly elucidate the significance of pyrophosphate elaboration in the process of normal bone mineralization and in the molecular etiology of the FGFR-associated craniosynostosis syndromes.


METHODS
Towards this goal we have constructed a PC-1 gene promoter/firefly luciferase reporter construct, in order to more directly investigate the regulation of PC-1 by FGF/FGFR signaling in osteoblastic and non-osteoblastic cells.


CONCLUSIONS
Preliminary results confirm that FGF/FGFR signaling, either via treatment with FGF2 or via expression of a Crouzon syndrome-associated mutant FGFR2, induces PC-1 promoter activity in osteoblastic cells in culture. This appears to be a cell type specific phenomenon. These results suggest that the expression of PC-1 downstream of FGF signaling is an integral aspect of osteoblastic function, and that pyrophosphate elaboration may play a significant role in the pathology of craniosynostosis.
Hatch
Nan E
NE
Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA. nhatch@umich.edu
D016475:3T3 Cells; D000818:Animals; D002113:Calcification, Physiologic / Q000235:genetics; D003398:Craniosynostoses / Q000235:genetics* / Q000378:metabolism; D011756:Diphosphates / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D049409:Luciferases, Firefly / Q000235:genetics / Q000378:metabolism; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011755:Pyrophosphatases / Q000096:biosynthesis / Q000235:genetics*; D051497:Receptor, Fibroblast Growth Factor, Type 2 / Q000502:physiology*; D015398:Signal Transduction; D015854:Up-Regulation
D011756:Diphosphates; D016222:Fibroblast Growth Factor 2; D049409:Luciferases, Firefly; D051497:Receptor, Fibroblast Growth Factor, Type 2; D010727:Phosphoric Diester Hydrolases; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1; D011755:Pyrophosphatases