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. 2010 Feb 22:10:22.
doi: 10.1186/1471-213X-10-22.

Activation of p38 MAPK pathway in the skull abnormalities of Apert syndrome Fgfr2(+P253R) mice

Yingli Wang  1 , Miao Sun, Victoria L Uhlhorn, Xueyan Zhou, Inga Peter, Neus Martinez-Abadias, Cheryl A Hill, Christopher J Percival, Joan T Richtsmeier, David L Huso, Ethylin Wang Jabs
Affiliations

Activation of p38 MAPK pathway in the skull abnormalities of Apert syndrome Fgfr2(+P253R) mice

Yingli Wang et al. BMC Dev Biol. .

Abstract

Background: Apert syndrome is characterized by craniosynostosis and limb abnormalities and is primarily caused by FGFR2 +/P253R and +/S252W mutations. The former mutation is present in approximately one third whereas the latter mutation is present in two-thirds of the patients with this condition. We previously reported an inbred transgenic mouse model with the Fgfr2 +/S252W mutation on the C57BL/6J background for Apert syndrome. Here we present a mouse model for the Fgfr2+/P253R mutation.

Results: We generated inbred Fgfr2(+/P253R) mice on the same C56BL/6J genetic background and analyzed their skeletal abnormalities. 3D micro-CT scans of the skulls of the Fgfr2(+/P253R) mice revealed that the skull length was shortened with the length of the anterior cranial base significantly shorter than that of the Fgfr2(+/S252W) mice at P0. The Fgfr2(+/P253R) mice presented with synostosis of the coronal suture and proximate fronts with disorganized cellularity in sagittal and lambdoid sutures. Abnormal osteogenesis and proliferation were observed at the developing coronal suture and long bones of the Fgfr2(+/P253R) mice as in the Fgfr2(+/S252W) mice. Activation of mitogen-activated protein kinases (MAPK) was observed in the Fgfr2(+/P253R) neurocranium with an increase in phosphorylated p38 as well as ERK1/2, whereas phosphorylated AKT and PKCalpha were not obviously changed as compared to those of wild-type controls. There were localized phenotypic and molecular variations among individual embryos with different mutations and among those with the same mutation.

Conclusions: Our in vivo studies demonstrated that the Fgfr2 +/P253R mutation resulted in mice with cranial features that resemble those of the Fgfr2(+/S252W) mice and human Apert syndrome. Activated p38 in addition to the ERK1/2 signaling pathways may mediate the mutant neurocranial phenotype. Though Apert syndrome is traditionally thought to be a consistent phenotype, our results suggest localized and regional variations in the phenotypes that characterize Apert syndrome.

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Figures

Figure 1
Figure 1
Abnormal gross appearance and histology of Fgfr2+/P253R mice. A-D) Alizarin red S and Alcian blue staining of the skull shows domed-shaped skulls with shortened anterioposterior length, short nasal snouts and upper jaw in mutant; I, J) Alizarin red S and Alcian blue staining of the chest shows abnormal bony fusion of sternum (white arrow) in mutant. E-H) Palate abnormalities: (E, F) Superior view shows a defect located at the junction between the primary and secondary palate in mutant (arrow). (G, H) Histology shows incomplete fusion in mutant (arrows). (K, L) Abnormal chondro-osseous transition at the physis in mutant (brackets). Panels A, C, E, G, I, and K are from littermate controls. Panels B, D, F, H, J, and L are the corresponding organs and tissues in mutant mice. (Scale bars: I-P = 50 μm).
Figure 2
Figure 2
Micro-CT of the skulls of Fgfr2+/P253R mice and wild-type littermates. A-D) Mutant skull is shorter in the rostro-caudal, maxilla, and mandible lengths than those of the wild-type controls. In the mutants, the zygomatic process of the maxilla and the malar bone are fused (B, D; white arrows) and unilateral or bilateral coronal synostosis occurs (B, D; black arrows). E, F) The developing mutant palates are shorter than the wild-type. In the mutants, the inter-premaxillary suture is patent (F; white arrow) with fusion of the premaxilla-maxillary sutures (F; black arrow). The suture between the horizontal plate of the palatine bone and palatal process of the maxilla is patent in Fgfr2+/P253R and wild-type (F; red arrow) but partially fused in Fgfr2+/S252W mice (not shown). The midline suture between the palatal shelves of the maxilla are patent in mutant mice as well as in some controls (F; blue arrow). Portions of the maxilla were darkened in Photoshop to allow observation of the fusion of the zygomatic process. Panels A, C, and E are from littermate controls. Panels B, D, and F are from Fgfr2+/P253R mice.
Figure 3
Figure 3
Morphometric analyses of the skulls of Fgfr2+/P253R and Fgfr2+/S252W mice. EDMA results from intra-model comparisons between mutant and normal littermates (for further details see Table 1). From top to bottom: superior, lateral and inferior views of micro-CT 3D reconstructions of the skull of a Fgfr2+/P253R mouse on the left, and of a Fgfr2+/S252W mouse on the right. Red lines indicate linear distances that are significantly shorter in both mutants in comparison with their littermate controls; blue lines represent linear distances that are significantly longer in mutants in comparison to their littermate controls; and green lines show linear distances that are similar in mutants and littermate controls (i.e. no statistical significant differences at the α = 0.1 level).
Figure 4
Figure 4
Histological analysis of the abnormal calvarial sutures in Fgfr2+/P253R mice. A-D) HE staining shows the abnormal development of the mutant coronal suture from P0 to P5 with presynostosis, disorganization of cells between the osteogenic fronts and osteoid deposition at P0 (A, B); and synostosis at P5 (C, D). E-H) HE staining shows the abnormal development of the mutant lambdoid (E, F) and sagittal suture (G, H) with proximate osteogenic fronts and cellular disorganization at P0. I, J) abnormal cartilage at the sagittal suture (blue arrows). Panels A, C, E, G and I are from littermate controls. Panels B, D, F, H and J are the corresponding regions in mutant mice. Black arrows, osteogenic fronts; arrowheads, presynostosis/synostosis. (Scale bars: A-D = 25 μm; E-J = 50 μm).
Figure 5
Figure 5
Abnormal proliferation, differentiation and no obvious change in apoptosis at the coronal suture in Fgfr2+/P253R mice. A, B) Immunohistochemical staining of BrdU shows decreased numbers and abnormal distribution of positive cells in mutants at E17.5 (arrow). C, D) ALP staining showed broad ALP domain and expansion of expression into the coronal suture of the mutants at E17.5 (arrow). E, F) Immunohistochemical staining of Runx2 shows increased expression and abnormal differentiation at the osteogenic fronts at E17.5 (arrow). G, H) In situ hybridization of osteonectin shows accelebrated bone formation in mutants at E17.5. I, J) TUNEL staining shows no clear difference in apoptosis between the mutant and wild-type at P5 (arrows). Panels A, C, E, G and I are from littermate controls. Panels B, D, F, H and J are the corresponding regions in mutant mice. (Scale bars: A-F = 50 μm).
Figure 6
Figure 6
Abnormal proliferation and differentiation at the chondro-osseous junction and metaphysis in Fgfr2+/P253R mice. A, B) BrdU staining shows increase in the numbers of proliferative cells in mutants at E19 (brackets). C-F) In situ hybridization of osteogenic markers shows increased expression in mutants at P0: (C, D) osteopontin; (E, F) bone sialoprotein expression. Panels A, C and E are from littermate controls. Panels B, D and F are the corresponding regions in mutant mice. (Scale bars: A-D = 50 μm).
Figure 7
Figure 7
Increased phosphorylated ERK1/2 and p38 and no change in phosphorylated PKCα and AKT in neurocranial tissues of Fgfr2+/P253R at E17.5. A-D) Western blot analysis of different markers shows increased phosphorylated ERK1/2 and p38 and no change in phosphorylated AKT and PKCα. E, F) Scatter plots using normalized levels of of mutant phos/total/control phos/total shows increased ratio of phosphorylated ERK1/2 and p38 to total protein in the Fgfr2+/P253R as compared to the wild-type neurocraniums. Each dot represents the analysis of data from one embryo. The bar represents the median value.
Figure 8
Figure 8
Increased phosphorylated ERK1/2 and p38 and no change in phosphorylated PKCα and AKT in skull base tissues of Fgfr2+/P253R at E17.5. A-D) Western blot analysis of different markers shows increased phosphorylated ERK1/2 and p38 and no change in phosphorylated AKT and PKCα. E, F) Scatter plots using normalized levels of of mutant phos/total/control phos/total shows increased ratio of phosphorylated ERK1/2 and p38 to total protein in the Fgfr2+/P253R as compared to the wild-type skull bases. Each dot represents the analysis of data from one embryo. The bar represents the median value.
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References

    1. Johnson DE, Lee PL, Lu J, Williams LT. Diverse forms of a receptor for acidic and basic fibroblast growth factors. Mol Cell Biol. 1990;10:4728–4736. - PMC - PubMed
    1. Olsen SK, Ibrahimi OA, Raucci A, Zhang F, Eliseenkova AV, Yayon A, Basilico C, Linhardt RJ, Schlessinger J, Mohammadi M. Insights into the molecular basis for fibroblast growth factor receptor autoinhibition and ligand-binding promiscuity. Proc Natl Acad Sci USA. 2004;101:935–940. doi: 10.1073/pnas.0307287101. - DOI - PMC - PubMed
    1. Eswarakumar VP, Lax I, Schlessinger J. Cellular signaling by fibroblast growth factor receptors. Cytokine Growth Factor Rev. 2005;16:139–149. doi: 10.1016/j.cytogfr.2005.01.001. - DOI - PubMed
    1. Ornitz DM, Itoh N. Fibroblast growth factors. Genome Biol. 2001;2:reviews3005. doi: 10.1186/gb-2001-2-3-reviews3005. - DOI - PMC - PubMed
    1. Miki T, Bottaro DP, Fleming TP, Smith CL, Burgess WH, Chan AM, Aaronson SA. Determination of ligand-binding specificity by alternative splicing: two distinct growth factor receptors encoded by a single gene. Proc Natl Acad Sci USA. 1992;89:246–250. doi: 10.1073/pnas.89.1.246. - DOI - PMC - PubMed

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