A Ser252Trp mutation in fibroblast growth factor receptor 2 (FGFR2) mimicking human Apert syndrome reveals an essential role for FGF signaling in the regulation of endochondral bone formation.
Here we investigate growth of the skull in two inbred mouse models each carrying one of two gain-of-function mutations in FGFR2 on neighboring amino acids (S252W and P253R) that in humans cause Apert syndrome, one of the most severe FGFR-related craniosynostosis syndromes.
We utilized a Fgfr2(+/S252W) mouse (a knock-in mouse model mimicking human AS) to demonstrate decreased bone mass due to reduced trabecular bone volume, reduced bone mineral density, and shortened growth plates in the long bones.
We detected several pathogenic mutations in 11/33 (33%) patients with Apert syndrome (four with p.Pro253Arg; seven with p.Ser252Trp) and 8/33 (24%) patients with Crouzon syndrome (three with p.Trp290Arg, one with p.Cys342Tyr, p.Cys278Phe, p.Gln289Pro, and a novel p.Tyr340Asn mutation) and five (15%) with Pfeiffer syndrome (p.Cys342Arg, p.Pro253Arg, p.Trp290Arg, and p.Ser351Cys).
Our results confirm a strong correspondence between genotype and facial phenotype for AS and MS with severity of facial dysmorphology diminishing from Apert FGFR2(S252W) to Apert FGFR2(P253R) to MS. We show that AS facial shape variation is increased relative to CS, although CS has been shown to be caused by numerous distinct mutations within FGFRs and reduced dosage in ERF.
Taking advantage of Apert syndrome mouse models, we performed a novel combination of morphometric, histological and immunohistochemical analyses to precisely quantify distinct palatal phenotypes in Fgfr2(+/S252W) and Fgfr2(+/P253R) mice.
We report two Indonesian patients with AS, in whom molecular analysis detected p.Ser252Trp (c.755C>G) and p.Pro253Arg (c.758C>G) mutations in the fibroblast growth factor receptor 2 (FGFR2) gene, respectively.
Bone formation and micro-architecture between 28- and 56-day-old mutant mice and controls were compared to investigate the changes in the mandibular micro-architecture caused by the Fgfr2(S252W/+) mutation to provide a basis for exploring the pathogenesis and therapeutic measures of human Apert syndrome.
Fibroblasts from 10 individuals each with Apert syndrome (FGFR2 substitution S252W), Muenke syndrome (FGFR3 substitution P250R), Saethre-Chotzen syndrome (various mutations in TWIST1) and non-syndromic sagittal synostosis (no mutation detected) were cultured.
Apert syndrome is one of the most severe craniosynostosis that is mainly caused by either a Ser252Trp(S252W) or Pro253Arg(P253R) mutation in fibroblast growth factor receptor 2 (FGFR2).
Because the periosteum contribution to AS cranial pathophysiology is unknown, we tested the osteogenic potential of AS periosteal cells (p.Ser252Trp mutation) and observed that these cells are more committed toward the osteoblast lineage.
C>G transversions at position 755 of FGF receptor 2 (FGFR2) cause Apert syndrome; this mutation, encoding the gain-of-function substitution Ser252Trp, occurs with a birth rate elevated 200- to 800-fold above background and originates exclusively from the unaffected father.
These results show that the S252W mutation in the FGFR2 gene enhances the osteoblast phenotype in human osteoblasts and that a soluble FGFR2 with the S252W mutation controls osteoblast differentiation induced by the S252W mutation through a dominant negative effect on FGFR2 signaling in Apert syndrome.
Here we show that mutant mice carrying the activation mutation, Ser252Trp [corrected] which corresponds to Ser252Trp in human FGFR2, have malformations mimicking the skull abnormalities found in AS patients.
Apert syndrome is a monogenic human disorder in which cleft palate has been significantly correlated to the fibroblast growth factor receptor (FGFR) 2-Ser252Trp mutation.
Two activating mutations, Ser-252 --> Trp and Pro-253 --> Arg, in fibroblast growth factor receptor 2 (FGFR2) account for nearly all known cases of AS.