NgR和NEP1-35结合小肽的设计筛选及其促中枢神经再生研究

发布时间：2017-12-28 16:11

本文关键词：NgR和NEP1-35结合小肽的设计筛选及其促中枢神经再生研究　出处：《第三军医大学》2006年博士论文　论文类型：学位论文

【摘要】： 成年哺乳动物中枢神经系统(central nervous system,CNS)损伤后难以再生,其结果就是某些功能的永久性丧失。而周围神经系统(peripheral nervous system,PNS)损伤后可以再生,并且在功能上也能得到较好的恢复。但是在受损的CNS部位移植胚胎周围神经组织等,却能观察到明显的再生现象,这提示CNS并非缺乏再生能力,而是损伤后的局部微环境中存在对再生不利的因素。目前已知,在CNS髓鞘中存在多种突起再生抑制性分子,如Nogo、髓鞘相关糖蛋白(myelin associated glycoprotein,MAG),少突胶质细胞相关糖蛋白(oligodendrocyte myelin associated glycoprotein,OMgp )等。为克服髓鞘抑制分子的作用,研究者们尝试了多种不同的方法,如,使用抗Nogo-A抗体IN-1,敲除Nogo基因和使用Nogo分子拮抗剂等,但是都没有取得非常令人满意的效果。近年来的研究发现Nogo有三种亚型,分别为Nogo-A、B和C,它们的C-末端高度同源,包括两个跨膜域和一个短的胞外环状结构(Nogo-66)。而在CNS中发挥抑制作用的亚型为Nogo-A,根据其发挥功能的途径可以分为amino-Nogo和Nogo-66两个部分。有趣的是OMgp、MAG和Nogo-A虽然在序列上没有相似性,但是却可以通过同一个受体NgR来传递信号,这也许是它们在空间结构上的相似性造成的结果。NgR没有胞内结构,只能通过共受体向下传递信号,RhoA是这条信息传导通路上的重要分子,直接或间接增强RhoA的表达可以抑制神经元轴突的生长。同时有研究显示,Nogo-66可能具有NgR识别域和NgR结合域,来自Nogo-66序列的小分子可以竞争性结合NgR,从而阻止Nogo-66与NgR的结合,克服髓鞘造成的抑制。Nogo是髓鞘抑制分子中被研究得较早和较为深入的一个,具有一定的代表性,但是,对于Nogo-66与NgR识别和激活的具体位点目前还没有报道。如果能够同时从Nogo-66和NgR两方面着手,阻止二者的识别,那么来自Nogo-66的抑制信号将从此中断,不再向下传递,使中枢神经元不会受到Nogo-66的影响,为再生创造有利的微环境。在本研究中,根据Nogo-66中NgR结合关键序列合成了两条含有10个氨基酸残基的小肽,肽II和肽III,并运用神经元原代培养、免疫组织(细胞)化学、RT-PCR等方法,研究了肽II和肽III对小脑颗粒细胞(cerebellum granule cell,CGC)突起生
[Abstract]:The adult mammalian central nervous system (central nervous system, CNS) is difficult to regenerate after injury, and the result is the permanent loss of certain functions. The peripheral nervous system (peripheral nervous system, PNS) can be regenerated after damage and can be well recovered in function. However, a significant regeneration phenomenon can be observed in transplantation of embryonic peripheral nerve tissue at the damaged CNS site. This indicates that CNS is not lack of regenerative ability, but there is an unfavorable factor for regeneration in the local microenvironment after injury. It is known that there are many kinds of neurite regeneration inhibitory molecules in CNS myelin sheath, such as Nogo, myelin associated glycoprotein (MAG), oligodendrocyte associated glycoprotein (oligodendrocyte myelin associated glycoprotein, OMgp). In order to overcome the effect of myelin inhibitor, researchers have tried many different methods, such as anti Nogo-A antibody IN-1, knockout Nogo gene and Nogo molecule antagonist, but have not achieved very satisfactory results. In recent years, there are three subtypes of Nogo, namely Nogo-A, B and C. Their C- ends are highly homologous, including two transmembrane domains and a short extracellular ring structure (Nogo-66). The subtype of inhibition in CNS is Nogo-A. According to its function, it can be divided into two parts: amino-Nogo and Nogo-66. Interestingly, though OMgp, MAG and Nogo-A have no similarity in sequences, they can transmit signals through the same receptor NgR, which may be the result of their similarity in spatial structure. NgR has no intracellular structure and can only transmit signals through a co receptor. RhoA is an important molecule in this information transduction pathway. Directly or indirectly enhancing the expression of RhoA can inhibit the growth of neuronal axons. Meanwhile, studies have shown that Nogo-66 may have NgR recognition domain and NgR binding domain, and small molecules from Nogo-66 sequences can compete with NgR to prevent Nogo-66 from binding to NgR and overcome myelin inhibition. Nogo is a relatively early and in-depth study of myelin inhibitory molecules. It has a certain representativeness. However, the specific loci for recognition and activation of Nogo-66 and NgR have not been reported yet. If we can start from the two aspects of Nogo-66 and NgR and prevent the identification of the two, then the inhibitory signals from Nogo-66 will be interrupted from this point, and no longer transmit down, so that the central neurons will not be affected by Nogo-66 and create favorable microenvironment for regeneration.
【学位授予单位】：第三军医大学
【学位级别】：博士
【学位授予年份】：2006
【分类号】：R341

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