Decreased RNA, and Increased RNA Oxidation, in Ribosomes from Early Alzheimer’s Disease

All cells rely on efficient protein synthesis in order to maintain cellular homeostasis. Recent studies from our laboratory indicate that declines in protein synthesis and ribosome function occur in the earliest stage of Alzheimer’s disease (AD). Additional studies indicate a potential role for ribosomal RNA oxidation as a potential mediator of decreased protein synthesis in AD. The ribosome is a complex of proteins and nucleic acids that mediates all protein synthesis. At present it is unclear if significant alterations in ribosomal RNA occurs within the ribosome complex during the progression of AD. In this study we examined the amount of ribosomal RNA in the different ribosomal fractions generated from control subjects, individuals with mild cognitive impairment (MCI), and individuals with AD. Studies were conducted in the inferior parietal lobule of each subject. Together, these data demonstrate that during the progression of AD there is a gross decline in the amount of ribosomal RNA within the ribosome complex. Additionally, these studies provide evidence for gross elevations in RNA oxidation within the ribosome complex of MCI and AD. Together, these data strongly suggest a role for RNA alterations within the ribosome as a mediator of decreased protein synthesis in both MCI and AD.     

RNA种类,结构及功能的多样性

ＲＮＡ是一类极其重要的生物大分子，它不仅种类繁多，而且其结构也比ＤＮＡ要复杂得多。不同种类的ＲＮＡ其结构虽有共同之处，但也有着显著的差异。由于ＲＮＡ种类和结构的多样性，这就决定了ＲＮＡ具有多种生物学功能。     

Buchnera aphidicola,the endosymbiont of aphids,contains genes for four ribosomal RNA proteins,initiation factor-3, and the α-subunit of RNA polymerase

Buchnera aphidicola is a prokaryotic endosymbiont of the aphidSchizaphis graminum. With the polymerase chain reaction (PCR) and oligonucleotide primers to conserved regions, two DNA fragments of the endosymbiont -operon and L20 operon were amplified, cloned intoEscherichia coli, and their sequences were determined. The results indicated that the organization of the endosymbiont genes on these fragments was identical with that of the corresponding operons ofE. coli. The 1032 base pair (bp) fragment of the -operon contained the genes for small ribosomal subunit proteins S11 and S4, followed by the gene for the -subunit of RNA polymerase (-RNAP). The 702-bp fragment of the L20-operon contained the genes for initiation factor-3 (IF3) and large ribosomal subunit proteins L35 and L20. As in other prokaryotes, the genes of the -operon and the L20-operon were present as single copies in the genome ofB. aphidicola. Comparisons of the amino acid sequences of these proteins were consistent with the previously established close relationship betweenB. aphidicola andE. coli and a distant relationship to species ofBacillus.     

SRA,作为RNA的核受体辅激活因子

类固醇受体激活物(SRA)是一个对类固醇受体AF-1结构域特异的辅激活因子,与大多数的核受体辅激活因子不同,它作为RNA存在并发挥作用。SRA可能作为类固醇受体的一种接头分子,赋予了类固醇受体募集辅激活因子复合物的特异性,从而调节了多种类固醇受体介导的转录。SRA的表达可能与人乳腺癌的发生和进程有关。     

RNA: Prebiotic Product,or Biotic Invention?

Spectacular advances in structural and molecular biology have added support to the 'RNA world' hypothesis, and provide a mandate for chemistry to explain how RNA might have been generated prebiotically on the early earth. Difficulties in achieving a prebiotically plausible synthesis of RNA, however, have led many to ponder the question posed in the title of this paper. Herein, we review recent experimental work on the assembly of potential RNA precursors, focusing on methods for stereoselective C-C bond construction by aldolisation and related processes. This chemistry is presented in the context of a broader picture of the potential constitutional self-assembly of RNA. Finally, the relative accessibility of RNA and alternative nucleic acids is considered.     

非编码RNA和RNA沉默

生物体内存在大量的非编码RNA ,它们形态各异 ,功能也千差万别 ,在生物的生长、发育、分化进程中扮演着不同的角色 ,尤其是siRNA ,它是RNA沉默的诱因。RNA沉默是真核生物特有的现象 ,它需要一系列因子的参与 ,其中RNA依赖性的RNA聚合酶是沉默起始的关键 ,Dicer酶是形成siRNA的基础 ,而RNA沉默诱导复合体 (RSIC)等是发生RNA沉默“链式反应”的关键因子     

Combinatorics of RNA–RNA interaction

RNA–RNA binding is an important phenomenon observed for many classes of non-coding RNAs and plays a crucial role in a number of regulatory processes. Recently several MFE folding algorithms for predicting the joint structure of two interacting RNA molecules have been proposed. Here joint structure means that in a diagram representation the intramolecular bonds of each partner are pseudoknot-free, that the intermolecular binding pairs are noncrossing, and that there is no so-called “zigzag” configuration. This paper presents the combinatorics of RNA interaction structures including their generating function, singularity analysis as well as explicit recurrence relations. In particular, our results imply simple asymptotic formulas for the number of joint structures.     

RNA编辑功能和RNA干扰

RNA编辑被认为是生命体一种新的基因加工与修饰现象,是指DNA转录成RNA后除RNA剪切外的其他加工过程,以核苷酸的删除、插入或替换等方式改变遗传信息,揭示生物进化过程中基因修饰和调控的另一个重要途径,是对中心法则的重要补充.而RNAi是一种由dsRNA介导的,在转录水平、转录后水平和翻译水平上阻断基因表达的基因调节途径.着重介绍 RNA编辑功能、RNA编辑与RNA干扰关系.     

RNA病毒RNA聚合酶的研究进展

自然界仅有ＲＮＡ病毒以ＲＮＡ作为基因载体。依赖于ＲＮＡ的ＲＮＡ聚合酶在这种病毒的增殖复制期起到了非常重要的作用。它一方面以病毒ＲＮＡ为模板复制子代病毒的基因,另一方面也将病毒增殖期间需要的蛋白质和酶类的基因转录成为ｍＲＮＡ,也就是说它担负了复制酶和转...     

干扰小RNA与微RNA

干扰小RNA（small interfering RNA;siRNA）和微RNA（microRNA;miRNA）是两种序列特异性地转录后基因表达的调节因子,它们的相关性密切,既具有相似性,又具有差异性。该文主要介绍这两种小RNA分子的产生、作用机制,以及两者之间的联系与区别。     

RNA病毒RNA依赖的RNA聚合酶的结构与功能

RNA病毒一般传播迅速,给人类和自然造成巨大危害和威胁.许多RNA病毒的结构蛋白在基础研究和应用方面已日趋完善.相比之下,就非结构蛋白(NS)所做的研究较少,存在许多未知问题.在这些非结构蛋白中,病毒自身编码的RNA依赖的RNA聚合酶(RNA-dependent RNA polymerase,RdRP)对病毒的复制起关键作用.对RdRP的研究不仅使对病毒RNA复制的机制更精细明了,且有可能提供新的抗病毒靶标和诊断试剂.本文对RdRP特别是动物RNA病毒RdRP的结果与功能作一综述.     

依赖RNA的RNA聚合酶介导RNA干扰的扩增效应

RNA干扰(RNA interference,RNAi)是一种非常高效的基因沉默效应,RNA依赖性RNA聚合酶(RNA—de—pendent RNA polymerase,RdRP)介导的扩增作用可能是RNAi具有高效性的一个主要原因。了解RdRP在生物体中存在的证据、RdRP及其复合体的结构、次级siRNA的产生及转移性RNAi的发生机制等问题,对深入理解RNAi的作用机制和促进RNAi的临床应用有重要意义。