IGF-1R基因变异在特发性矮小症发病中的作用及机制

The pathogeny of idiopathic short stature（ISS）is still not undefined,and GH-IGF axis plays an important role in its pathogenesis.IGF-1R is the effector molecules to adjust the axis.According to foreign reports, IGF-1R genovariation may cause height variation of normal person and series nanism of intrauterine growth retardation.Our preliminary study also indicates that the IGF-1R gene SNP is related to the attack of ISS, but its mechanism of action is still not defined.For this purpose,we put forward the hypothesis: IGF-1R genovariation causes the change of protein function, thus affects GH-IGF signal pathway and causes the attack of ISS.In the experiment,IGF-1R mutant genes will be screened from the ISS cases. Through the structuring and assessment of the expression plasmid of IGF-1R ,we study the influence of different genovariation loca of IGF-1R on protein-encoding and analyze the clinical characteristics by using the R cell which means the directional blocking to IGF-1R gene to express the wild-type IGF-1R and the variant IGF-1R.We discuss the important role of IGF-1R played in the attach of ISS through molecular cell, clinical test, etc., thus to elaborate the regulation mechanism that IGF-1R genovariation affects IGF signal pathway and causes the attack of ISS, lay the solid foundation for revealing pathogenesis of ISS, and provide new thinking for preventing and treating the ISS.

特发性矮小症（ISS）病因不明，GH-IGF通路在发病中起重要作用，IGF-1R是调节该轴的效应分子。国外报道IGF-1R基因变异可引起正常身高变异和宫内发育迟缓儿的严重矮小，我们前期研究也提示IGF-1R基因SNP与ISS发病相关，但作用机制尚不清楚。为此，我们提出假说：IGF-1R基因变异引起蛋白功能改变从而影响IGF信号通路，导致ISS的发生。本实验将在ISS病例中筛选IGF-1R变异基因，通过IGF-1R 基因表达质粒的构建、鉴定，利用定向阻断IGF-1R基因的R细胞表达野生型和变异型IGF-1R，研究IGF-1R不同基因变异位点对编码蛋白功能的影响，并分析临床特点。从分子细胞结合临床等多方面探讨IGF-1R基因在ISS发病中的重要作用，从而阐明IGF-1R基因变异影响IGF信号通路导致ISS发病的调控机制，为揭示ISS的发生机制奠定基础，为ISS的防治提供新的思路。

本项目紧紧抓住特发性矮小症“IGF1R基因变异”之关键环节，构建矮小症NGS芯片，从而快速筛查ISS患儿IGF-1R基因突变，寻找致病基因突变位点及类型，并将突变定位在受体不同区域的分布（跨膜区、胞外区与胞浆区），分析其与临床表型的关系。.构建了矮小NGS芯片包，可快速筛查与矮小相关的277个基因，发现可疑致病位点后，采用Sanger测序对患者及父母进行突变筛查。构建野生型及突变基因（选择新发的有代表性的突变位点）的过表达腺病毒载体，建立腺病毒表达载体。在细胞水平上，比较野生型及不同突变基因的编码蛋白在mRNA转录、蛋白表达、细胞内定位、激素-受体结合及受体后信号转导通路等方面的差异：初步检测了IGF-1R突变后IGF1R mRNA和蛋白表达情况，获得了IGF-1R突变后对下游信号通路AKT1影响，初步进行了基因功能分析。在IGF-1R基因变异影响IGF-1R不同功能表达的基础上，从病史、临床表现、实验室检查（精氨酸 GH 基础值峰值、可乐定GH基础值峰值、IGF-1、IGF-1SDS、IGFBP3、IGFBP3SDS、血脂、OGTT试验、C肽、胰岛素、HOMA稳态模型指数）、骨龄、GH治疗有效性等方面总结IGF-1R基因不同功能表达异常的临床特点，为ISS的防治提供新的思路。.本课题全面完成研究计划，发表学术论文2篇（标注资助），并培养硕士生6名。