先天性甲状腺发育不全新候选致病基因NKX6.2的分子致病机制及其遗传学研究

甲状腺发育不全（TD）包括甲状腺缺如、异位和发育不良，约占先天性甲状腺功能低下 （CH）85%。遗传因素是TD重要原因，仅为数不多致病基因被发现。前期对381例TD患儿全外显子重测序发现NKX6.2是TD候选致病基因。本研究已构建nkx6.2敲降引起斑马鱼发育滞后畸形等CH模型，拟系统阐述nkx6.2在甲状腺发育中作用；采用RNA测序筛选与体内外实验证实nkx6.2与jag1-Notch的靶向关系，通过激活和抑制Notch通路，阐明nkx6.2与jag1-Notch信号通路互作对甲状腺发育的影响。依托已建立大型CH资源库，对800例TD采用Miseq高通量二代测序进行NKX6.2遗传学验证，以鉴定新TD致病基因;探究已发现4个新NKX6.2错义突变对JAG1启动子区激活与结合能力、蛋白核定位和细胞增殖与迁移等影响，揭示TD分子致病机理。本研究将为CH遗传学干预与治疗及产前诊断提供新理论依据

Thyroid dysgenesis (TD) includes thyroid agenesis, hypoplasia and ectopic, accounting for 85% of congenital hypothyroidism ( CH ). Genetic factor is an important cause of TD. Currently, only a few TD causive candidate genes have been found. In our previous study, we have found that NKX6.2 may be the candidate gene for TD by whole exome sequencing of 381 TD cases. In this study, a CH model of zebrafish caused by nkx6.2 knockdown has been established to systematically explain the role of nkx6.2 in thyroid development; the targeted relationship between nkx6.2 and Jag1-notch signal pathway verified by RNA-sequencing screening will be validated in vivo and in vitro, and the effect of nkx6.2- Jag1-Notch interaction on thyroid development will be clarified by activating and inhibiting Notch pathway. Besides, based on the a large-scale established CH genetic resource database , we proposed to verify the genetic mutations in the whole NKX6.2 by the Miseq next generation high-throughput sequencing in 800 TD cases in the Chinese population to identify new pathogenic gene for TD. Furthermore, on the basis of 4 novel missense mutations in NKX6.2, we will explore the effects of these NKX6.2 mutations on Jag1 promoter activation ability, protein binding capacity, protein nuclear localization and cell proliferation and migration further to reveal the molecular pathogenesis of TD. This study will provide a new theoretical basis for the genetic intervention and treatment and prenatal diagnosis.