单细胞生物绿藻—衣藻中小RNAs的系统研究及亚洲病人起源的禽流感病毒H5N1表面糖蛋白的序列和表面抗原分析

发布时间：2018-10-26 19:29

【摘要】： 第一部分在RNA干涉(RNAi)途径中,内生小RNAs对于基因的表达与调控起着非常重要的作用,这些小RNAs作用方式有三种:靶标信使RNA的裂解,靶标信使RNA的抑制以及染色质的修饰。植物和动物包含许多微小RNAs—microRNAs (miRNAs),这些miRNAs在包括细胞分化,器官形态建成等许多发育相关生理现象中扮演着至关重要的作用。目前,还没有miRNAs在单细胞生物中报道。本论文中,我们首次发现单细胞生物绿藻—衣藻(Chlamydomonas reinhardtii)编码许多miRNAs。我们也发现衣藻miRNA在体内和体外都能指导它的靶标mRNA裂解。我们还在衣藻配子产生过程中探究了衣藻miRNA的表达丰度变化情况。除了miRNAs,衣藻体内还包括许多类型的小RNA,一类是phasing siRNAs,这些phasing siRNAs很象植物trans-acting siRNAs,另一类是siRNAs,它们来自于编码蛋白的基因和转座子中。我们的发现表明miRNA途径和一些siRNA途径对于基因的表达与调控是古老的,它们在多细胞生物出现之前就存在。第二部分世界卫生组织(WHO)对人类感染高致病性禽流感病毒H5N1的报道显示,人类感染H5N1的事例越来越多,这引起了全世界人民的极大恐慌。血凝素(HA)和神经氨酸酶(NA)是禽流感病毒H5N1的两种主要抗原。通过HA和NA两种表面糖蛋白的点突变,H5N1禽流感病毒一方面可以扩大自己的宿主感染范围,另一方面可逃避宿主免疫系统对它的识别。通过生物信息学的方法,对亚洲病人来源的H5N1禽流感病毒的HA和NA序列进行了全面分析后,我们发现了许多新的HA和NA突变位点,并且一些突变位点对于人来说是致死的,我们对HA和NA的这些突变特性(包括突变位点的氨基酸属性,受体结合属性以及表面抗原属性等)进行了详细的分析。通过蛋白三级结构建模,我们还发现了HA的一个受体结合位点的改变或许涉及到宿主专一性的改变。总之,我们的结果一方面有利于病毒学家进行实验设计,深入理解流感病毒的致病性机理,另一方面为全面理解流感病毒在亚洲的进化趋势提供了理论依据,对设计禽流感疫苗,进行流感病毒的预防具有重要意义。
[Abstract]:In the first part, endogenous small RNAs plays a very important role in gene expression and regulation in the RNA interference (RNAi) pathway. These small RNAs functions in three ways: the cleavage of target messenger RNA, the inhibition of target messenger RNA and the modification of chromatin. Plants and animals contain many tiny RNAs-microRNAs (miRNAs),. These miRNAs play a crucial role in many developmental physiological phenomena, including cell differentiation, organ morphogenesis and so on. Currently, no miRNAs has been reported in single-celled organisms. In this paper, we found for the first time that Chlamydomonas (Chlamydomonas reinhardtii), a single-celled organism, encodes many miRNAs.. We also found that Chlamydomonas miRNA can direct its target mRNA cleavage in vivo and in vitro. We also investigated the expression abundance of Chlamydomonas miRNA during gametes production. In addition to miRNAs, Chlamydomonas, there are many types of small RNA, that are phasing siRNAs, phasing siRNAs that is very similar to plant trans-acting siRNAs, and siRNAs, which comes from genes and transposons that encode proteins. Our findings suggest that the miRNA pathway and some siRNA pathways are ancient for gene expression and regulation, and that they existed before the emergence of multicellular organisms. The second part of the World Health Organization (WHO) (WHO) report on human infection with highly pathogenic avian influenza virus (H5N1) shows that there are more and more cases of human infection with H5N1, which has caused great panic around the world. Hemagglutinin (HA) and neuraminidase (NA) are two major antigens of avian influenza virus H5N1. Through the point mutation of HA and NA, H5N1 avian influenza virus can expand its host infection range on the one hand, on the other hand, it can evade the host immune system to recognize it. After a comprehensive analysis of the HA and NA sequences of H5N1 avian influenza virus from Asian patients by bioinformatics, we found many new HA and NA mutation sites, some of which are lethal to humans. We analyzed the mutation characteristics of HA and NA in detail, including amino acid properties, receptor binding properties and surface antigen properties of mutation sites. We also found that the alteration of a receptor binding site in HA may involve host specific changes. In a word, our results, on the one hand, are conducive to virologists' experimental design and in-depth understanding of the pathogenicity of influenza viruses, and on the other hand provide a theoretical basis for a comprehensive understanding of the evolution of influenza viruses in Asia. It is of great significance to design bird flu vaccine and prevent influenza virus.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2007
【分类号】：R373;R392

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