泛素连接酶NEDL2的生理功能及分子机制研究

发布时间：2018-05-22 07:15

本文选题：NEDL2 + 肠神经系统　；参考：《清华大学》2015年博士论文

【摘要】：泛素连接酶(E3)是真核生物体内泛素-蛋白酶体降解系统的关键组分,决定识别底物的特异性,挖掘E3的新功能是E3研究领域的一个热点。根据结构特点,可将E3分为两大类:RING(really interesting new gene)锌指结构域类和HECT(homologous to E6AP C-terminus)结构域类。NEDL2是HECT类泛素连接酶Nedd4家族9个成员中了解最少的分子,其泛素化底物和生理功能均未见报道。为揭示NEDL2和其在Nedd4家族中同源性最高的分子NEDL1的生理功能,近期我们建成了NEDL1和NEDL2基因敲除小鼠模型,表型分析发现NEDL2-/-小鼠出生后两周内全部死亡,表明NEDL2为小鼠早期发育所必需。其中,100%的小鼠伴随着肠道严重胀气及肠动力不足,33%的小鼠出现单侧或双侧肾脏水肿,还发现NEDL2-/-小鼠肠道神经系统严重发育不良。虽然NEDL1和NEDL2具有高达69%的一致性,但是NEDL1-/-小鼠并没有类似NEDL2-/-小鼠的表型,差别明显,NEDL1-/-小鼠在生存、生殖等方面均无异常。肠神经系统属机体内最大的外周神经系统,对机体稳态的维持发挥重要的作用。肠神经系统发育异常将导致多种疾病的发生,其中最典型的疾病是先天巨结肠疾病(Hirschsprung disease,HSCR)。GDNF-RET信号通路是调控肠神经系统发育最重要的信号通路。同时,GDNF-RET信号通路也是调控肾脏发育最重要的信号通路。肾脏同样在维持机体的稳态中发挥重要的作用,主要调控机体的水平衡、酸碱平衡等。肾脏发育的异常同样会引起一系列疾病的发生,例如肾炎。我们的研究发现,NEDL2是肠神经系统和肾脏发育过程中一个重要的正调控分子。NEDL2的敲除导致肠神经元的数量明显不足,且GDNF-RET-AKT信号通路活性明显降低;肾脏出现明显的水肿且出现多个空囊,肾小球数量明显较少及血清中尿素氮的含量明显升高。综上所述,本课题系统分析了NEDL2-/-小鼠的表型,探讨NEDL2与调控肠神经系统及肾脏发育最重要的GDNF-RET信号通路间的调控关系。本研究首次揭示了NEDL2在肠神经系统及肾脏发育中的重要功能并试探其作用机制。这为进一步探讨NEDL2的新功能奠定了基础,为加深人们对Nedd4家族的新功能提供了更多的认识,为深入研究HSCR疾病提供了一种新的小鼠模型。
[Abstract]:Ubiquitin ligase E3) is a key component of Ubiquitin proteasome degradation system in eukaryotes, which determines the specificity of substrate recognition. According to the structural characteristics, E3 can be divided into two categories: HECT(homologous really interesting new gene) zinc-finger domain and HECT(homologous to E6AP C-terminus.NEDL2 is the least known member of the Nedd4 family of HECT class ubiquitin ligase, whose ubiquitin substrate and physiological function are not reported. In order to reveal the physiological function of NEDL2 and its most homologous molecule NEDL1 in the Nedd4 family, we recently established the NEDL1 and NEDL2 gene knockout mice model. Phenotypic analysis showed that NEDL2-r / -mice died within two weeks of birth. It is suggested that NEDL2 is necessary for early development of mice. Among them, 100% of the mice developed unilateral or bilateral renal edema with severe flatulence of the intestine and 33% of the mice with insufficient intestinal motility, and NEDL2-r-mice were found to have severe intestinal nervous system dysplasia. Although NEDL1 and NEDL2 have a high consistency of 69%, NEDL1-r-mice do not have the same phenotype as NEDL2-r-mice, and the difference is obvious that NEDL1-r-mice have no abnormality in survival, reproduction and so on. The enteric nervous system is the largest peripheral nervous system in the body and plays an important role in the maintenance of homeostasis. Abnormal development of intestinal nervous system will lead to many diseases. The most typical disease is Hirschsprung disease HSCRN. GDNF-RET signaling pathway is the most important signal pathway to regulate the development of enteric nervous system. At the same time, GDNF-RET signaling pathway is also the most important signal pathway to regulate renal development. Kidney also plays an important role in maintaining homeostasis, mainly regulating water balance, acid-base balance and so on. Abnormal kidney development can also lead to a range of diseases, such as nephritis. Our study found that NEDL2 is an important positive regulatory molecule in the development of the enteric nervous system and kidney. The knockout of NEDL2 leads to a significant shortage of the number of intestinal neurons and a significant decrease in the activity of GDNF-RET-AKT signaling pathway. There were obvious edema and multiple empty capsules in the kidney, the number of glomeruli was significantly less and the content of urea nitrogen in serum was significantly increased. To sum up, we systematically analyzed the phenotypes of NEDL2-r-mice, and explored the regulatory relationship between NEDL2 and GDNF-RET signaling pathway, which is the most important signal pathway for the development of the enteric nervous system and kidney. This study for the first time revealed the important function of NEDL2 in the development of enteric nervous system and kidney and explored its mechanism. It lays a foundation for further study of the new function of NEDL2, provides more understanding of the new function of Nedd4 family, and provides a new mouse model for the further study of HSCR diseases.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R363

【相似文献】