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Molecularbiological study of craniofacial dysmorphology in transgenic mice bearing Apert type mutant Fgfr2 gene

Apert型突变Fgfr2基因转基因小鼠颅面畸形的分子生物学研究

基本信息

批准号：
14571883
负责人：
NAGATA Masaki
金额：
$ 2.62万
依托单位：
NIIGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

To test a hypothesis that the cartilage is another target for the mutant FGFR2 signaling, we generated transgenic mice expressing Fgfr2 IIIc bearing Apert syndrome type mutation (Fgfr2 IIIc^<P253R>) selectively in chondrocytes. These mice markedly manifested deformities of the cranium including premature fusion of cartilaginous sutures in the cranial base(synchondroses), which accompanied by domed skull with wide opened metopic suture, maxillary hypoplasia, and shortening of anterior cranial base. As a likely cause of the prominent cranial deformities, we hypothesized specific expression patterns of FGF ligands that could produce aberrant FGFR2 signaling in cranial cartilage. The results of gene expression analyses by Lasermicrodisection(LMD)/Real time PCR(R-PCR) and organ culture system with FGFs stimulation demonstrated the acquirement of edopic autocrine regulation by Fgfi2 IIIc^<P253R> expression in concert with the specific distribution pattern of FGF2 and FGF10 ligand in cranial base cartilage. These results propose importance role of abnormal development of the cranial base cartilage as another basic mechanism of the preferential craniofacial dysmorphologies in Apert syndrome. To clarify the biological effect of activation of FGFR2 signaling, we used the LMD/R-PCR system to analyze the differentiation markers for chondrocyte lineage cells. Consistent with histological findings, LMD/R-PCR data have suggested activation of the molecules, Cbfa1, Ihh and MMP-13,which are involved in hypertrophic differentiation of the chondrocyte. Taken together, aberrant activation of FGFR2 signaling in cranial cartilage could result acceleration of chondrocyte terminal differentiation, consequently, resulting the craniofacial dysmorphology with premature fusion of cranial synchondroses.

为了验证软骨是突变的FGFR2信号转导的另一个目标的假设，我们在软骨细胞中选择性地产生了携带Apert综合征类型突变(FGFR2 IIIc；P253R&gt；)的表达FGFR2 IIIc的转基因小鼠。这些小鼠表现出明显的颅骨畸形，包括颅底软骨缝过早融合(合并症)，并伴有穹顶状颅骨和大开阔的异位缝合，上颌骨发育不良和前颅底缩短。作为突出颅骨畸形的可能原因，我们推测成纤维细胞生长因子配体的特定表达模式可能会在颅骨软骨中产生异常的FGFR2信号。激光显微切割(LMD)/实时定量聚合酶链式反应(R-PCR)和FGFs刺激的器官培养系统的基因表达分析结果表明，FGF2的异位自分泌调节与FGF2和FGF10配体在颅底软骨中的特殊分布模式相一致。这些结果表明，颅底软骨发育异常是Apert综合征优先发生颅面畸形的另一个基本机制。为了阐明FGFR2信号激活的生物学效应，我们利用LMD/R-PCR系统对软骨细胞系细胞的分化标志物进行了分析。与组织学结果一致的是，LMD/R-PCR数据表明参与软骨细胞肥大分化的分子Cbfa1、IHH和MMP-13被激活。综上所述，FGFR2信号在颅骨软骨中的异常激活可能导致软骨细胞终末分化加速，从而导致颅面畸形并伴有颅突软骨的过早融合。