表观遗传因素在RNA剪接过程中的作用

RNA剪接是真核生物基因表达过程中的重要环节,增加了蛋白质的多样性和基因表达的可调节性. 日益增多的研究表明,RNA剪接并不是独立的生物过程.RNA Ⅱ型聚合酶(RNA polymerase-Ⅱ, RNA Pol Ⅱ)、核小体定位和组蛋白修饰等因素都与RNA剪接过程密切相关.阐明RNA Pol Ⅱ、核小体定位和组蛋白修饰等因素在RNA剪接过程中的作用,将为剪接位点的准确识别和剪接调控机制的研究提供新思路.本文综述了RNA Pol Ⅱ、核小体定位和组蛋白修饰等因素对RNA剪接的影响以及它们在RNA剪接过程中的调控作用.     

Getting to the end of RNA: Structural analysis of protein recognition of 5′ and 3′ termini

The specific recognition by proteins of the 5′ and 3′ ends of RNA molecules is an important facet of many cellular processes, including RNA maturation, regulation of translation initiation and control of gene expression by degradation and RNA interference. The aim of this review is to survey recent structural analyses of protein binding domains that specifically bind to the extreme 5′ or 3′ termini of RNA. For reasons of space and because their interactions are also governed by catalytic considerations, we have excluded enzymes that modify the 5′ and 3′ extremities of RNA. It is clear that there is enormous structural diversity among the proteins that have evolved to bind to the ends of RNA molecules. Moreover, they commonly exhibit conformational flexibility that appears to be important for binding and regulation of the interaction. This flexibility has sometimes complicated the interpretation of structural results and presents significant challenges for future investigations.     

Utilization of Messenger in Adenovirus-2-infected Cells at Normal and Elevated Temperatures

THE regulation of protein synthesis in eukaryotic cells appears to be distinctly different from that in prokaryotes. The long-lived messenger RNA in eukaryotes suggests that control of protein synthesis occurs partially at the level of translation and regulation at the level of initiation of translation of messenger RNA has been found under several different conditions in mammalian cells^1–6.     

Epigenetic gene regulation by noncoding RNAs

Functional noncoding RNAs have distinct roles in epigenetic gene regulation. Large RNAs have been shown to control gene expression from a single locus (Tsix RNA), from chromosomal regions (Air RNA), and from entire chromosomes (roX and Xist RNAs). These RNAs regulate genes in cis; although the Drosophila roX RNAs can also function in trans. The chromatin modifications mediated by these RNAs can increase or decrease gene expression. These results suggest that the primary role of RNA molecules in epigenetic gene regulation is to restrict chromatin modifications to particular regions of the genome. However, given that RNA has been shown to be at the catalytic core of other ribonucleoprotein complexes, it is also possible that RNA also plays a role in modulating changes in chromatin structure.     

RNA剪接和剪接调控

ＲＮＡ剪接和剪接调控桂建芳（中国科学院水生生物研究所武汉４３００７２）基因是遗传的功能单位,蛋白是由基因表达的行使生理功能的主体。７０年代以前,人们对基因和蛋白的了解主要是来自于对细菌研究的认识,认为基因、ｍＲＮＡ和蛋白之间是一种线性关系,即基因上的脱氧核苷顺序全部转录成ｍＲＮＡ上的核苷顺序,ｍＲＮＡ上的核苷顺序再全部翻译成蛋白上的氨基酸顺序。     

Stringent control of RNA synthesis inLactobacillus acidophilus

The amino acid regulation of RNA synthesis inLactobacillus acidophilus was studied and found to be of stringent character. The synthesis of RNA was inhibited in the absence of essential amino acids in the medium, this inhibition being released by chloramphenicol or chlortetracycline. The RNA synthesized in the presence of the above inhibitors was not stable. The results do not support the hypothesis that the release of RNA synthesis by chloramphenicol is due to an increased pool of free amino acids, in consequence to the inhibition of protein synthesis. Chloramphenicol removed the inhibition of RNA synthesis at the same rate as the amino acids themselves. The pool of free leucine or histidine decreased to 60% in the absence of exogenous amino acids and it was not raised on adding chloramphenicol. The results are in agreement with the assumption that the synthesis of ribosomal RNA in bacteria is controlled by the equilibrium between polysomes and free ribosomes. Further, the results point to a possible limiting role of proteins in the regulation of ribosomal RNA synthesis.     

Defense Response to Pathogens Through Epigenetic Regulation in Rice

Epigenetic factors have recently emerged as key regulators of the defense response to pathogens in plants. The epigenetic mechanisms underlying defense regulation have been investigated mostly in Arabidopsis, while our understanding of the epigenetic regulation of defense in rice is limited. In this review, we summarize recent findings surrounding epigenetic mechanisms for defense in rice, primarily focusing on DNA methylation, histone modification, and small RNA regulation. In particular, we focused on RNA-directed DNA methylation (RdDM) and other epigenetic regulatory mechanisms that are involved in disease resistance. Finally, we explored potential epigenetic factors that might regulate the defense response in rice by analyzing available microarray data that can be used to uncover details of epigenetics regulation.     

Key players in regulatory RNA realm of bacteria

Precise regulation of gene expression is crucial for living cells to adapt for survival in diverse environmental conditions. Among the common cellular regulatory mechanisms, RNA-based regulators play a key role in all domains of life. Discovery of regulatory RNAs have made a paradigm shift in molecular biology as many regulatory functions of RNA have been identified beyond its canonical roles as messenger, ribosomal and transfer RNA. In the complex regulatory RNA network, riboswitches, small RNAs, and RNA thermometers can be identified as some of the key players. Herein, we review the discovery, mechanism, and potential therapeutic use of these classes of regulatory RNAs mainly found in bacteria. Being highly adaptive organisms that inhabit a broad range of ecological niches, bacteria have adopted tight and rapid-responding gene regulation mechanisms. This review aims to highlight how bacteria utilize versatile RNA structures and sequences to build a sophisticated gene regulation network.