Basic fibroblast growth factor: effects on matrix remodeling, receptor expression, and transduction pathway in human periosteal fibroblasts with FGFR2 gene mutation.
The Crouzon syndrome, which is associated with fibroblast growth factor receptor (FGFR2) mutations, is characterized by premature fusion of cranial sutures. We used an in vitro model of cultured periosteal fibroblasts from normal subjects and from Crouzon patients with FGFR2 mutation. We analyzed the matrix turnover rate and the effects of adding FGF2 by evaluating fibronectin synthesis and the activity of some proteolytic enzymes. To assess the role of some FGF signaling molecules involved in FGFR2 regulation, we studied Grb2 tyrosine phosphorylation and the phosphotyrosine proteins associated with Grb2. The iodinate FGF binding assay was performed to quantify FGFR expression. Compared with normal fibroblasts, fibronectin synthesis was decreased in Crouzon fibroblasts, and protease activities in cells and medium were enhanced, suggesting that excess fibronectin catabolism is present. Differences were more marked when FGF2 was added. Very few phosphoproteins were visible in anti-Grb2 immunoprecipitations from Crouzon fibroblasts, which showed a significant increase in the number of high-affinity and low-affinity FGF2 receptors. These results suggest that the abnormal genotype and the Crouzon cellular phenotype are related. To compensate the low levels of tyrosine phosphorylation, Crouzon cells might increase the numbers of FGFR2, thus increasing the cell surface binding sites for FGF2.
Bodo
Maria
M
Sezione di Istologia ed Embriologia Sperimentale-Fac. Medicina, Università di Perugia, Italia. bodo@unipg.it
Lilli
Cinzia
C
Aisa
Maria Cristina
MC
Scapoli
Luca
L
Bellucci
Catia
C
Rinaldi
Eliana
E
Tosi
Lara
L
Baroni
Tiziano
T
Conte
Carmela
C
Bellocchio
Silvia
S
Carinci
Francesco
F
Stabellini
Giordano
G
Carinci
Paolo
P
D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D002401:Cathepsin B / Q000032:analysis; D003394:Craniofacial Dysostosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D010450:Endopeptidases / Q000032:analysis; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005347:Fibroblasts / Q000737:chemistry*; D005353:Fibronectins / Q000096:biosynthesis / Q000187:drug effects; D051380:GRB2 Adaptor Protein; D006801:Humans; D007610:Kallikreins / Q000032:analysis; D010521:Periosteum / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D010960:Plasminogen Activators / Q000032:analysis; D017354:Point Mutation; D011506:Proteins / Q000378:metabolism; D017468:Receptors, Fibroblast Growth Factor / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D005353:Fibronectins; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D011506:Proteins; D017468:Receptors, Fibroblast Growth Factor; D016222:Fibroblast Growth Factor 2; D014443:Tyrosine; D010450:Endopeptidases; D007610:Kallikreins; D010960:Plasminogen Activators; D002401:Cathepsin B