FGF/FGFR2通过Wnt信号促进Apert综合征矢状缝异常软骨形成的作用与机制研究

Ectopic cartilage formation in sagittal suture is the important factor to cause parietal deformity of Apert syndrome (AS). Thus, it has the important meaning for treatment of Apert syndrome to clarify the cellular and molecular mechanisms of the formation of ectopically cartilage. Literature and our previous work suggested that FGFR2 may enhance the Wnt signaling promotes the differentiate of mesenchymal stem cells (MSCs) into cartilage cells, which resulting in abnormal cartilage formation, in sagittal suture of AS. In this study we first establish mice model of overexpressed and knockout beta-catenin in Apert mice, and the skull and cranial suture morphology will be analyzed to observation the roles of Wnt signal in abnormal cartilage formation of Apert sagittal suture. Combined with analysis the effects of osteogenic, chondrogenic differentiation, proliferation, apoptosis of mesenchymal cell lines and primary MSCs came from AS mice by regulating the expression of FGFR2 and Wnt signaling. Then, based on the previous work，we will evaluate the effects of treatment of AS skull by intervention Wnt signal in local suture in vitro and in vivo. This study will exhibit experimental basis for treatment of deformity of Apert skull through biological treatment.

矢状缝异常软骨形成是导致Apert综合征颅顶畸形的重要因素，弄清其病理发生的细胞及分子机制，对囟门早闭头颅畸形的治疗具有重要意义。文献及前期工作提示Apert中FGFR2可能通过增强Wnt信号促进矢状缝处的间充质干细胞（MSCs）向软骨细胞分化，导致异常软骨形成。本课题拟建立Apert小鼠中增强和敲除β-catenin的小鼠模型，对其头颅及颅缝形态进行分析，观察Wnt信号在Apert矢状缝异常软骨形成中的作用。结合间充质细胞系及分离的原代MSCs，对FGF/ FGFR2、Wnt信号进行干预，通过定向诱导分化，分析成骨、软骨细胞增生、分化、凋亡的影响，明确FGFR2调控Wnt信号在MSCs成骨、成软骨分化中的作用和机制。在上述工作基础上，用Apert小鼠进行体外及活体颅缝局部干预Wnt信号后对头颅形态进行分析，为开发通过干预Wnt信号来缓解Apert头颅畸形的生物治疗措施提供实验依据。

矢状缝异常软骨形成是导致Apert综合征颅顶畸形的重要因素，弄清其病理发生的细胞及分子机制，对囟门早闭头颅畸形的治疗具有重要意义。本课题观察到Apert小鼠矢状缝处有异位软骨细胞形成，而对照小鼠没有发现异位软骨。通过检测颅骨组织中Wnt信号通路相关基因表达，发现Apert小鼠中FGFR2增强突变激活了Wnt信号通路。通过成骨细胞、软骨细胞及中枢神经系统祖细胞特异表达FGFR2-P253R突变及头颅形态分析后，我们发现颅顶、颅底软骨连接、大脑特异激活Fgfr2-P253R均能导致与Apert部分相似的头颅畸形，表明Apert小鼠头颅畸形是由成骨组织、软骨组织、中枢神经系统组织异常发育共同作用的结果。用特异作用于Fgfr2-P253R的siRNA处理Apert小鼠颅骨细胞及体外培养的颅骨可缓解颅骨及细胞异常表型，表现为缓解成骨细胞的分化及改善冠状缝的闭合状态。AAV病毒介导的shRNA进行颅缝局部注射可改善Apert小鼠冠状缝的闭合状态。上述研究结果加深了我们对Apert头颅畸形形成机制的认识，为临床上Apert病人头颅畸形的生物治疗措施提供理论依据，也为其它骨骼基因遗传疾病的治疗提供借鉴。