RNA is involved in the regulation of multiple cellular processes, often by forming sequence-specific base pairs with cellular RNA or DNA targets that must be identified among the large number of ...nucleic acids in a cell. Several RNA-based regulatory systems in eukaryotes, bacteria and archaea, including microRNAs (miRNAs), small interfering RNAs (siRNAs), CRISPR RNAs (crRNAs) and small RNAs (sRNAs) that are dependent on the RNA chaperone protein Hfq, achieve specificity using similar strategies. Central to their function is the presentation of short 'seed sequences' within a ribonucleoprotein complex to facilitate the search for and recognition of targets.
Bacteria are an exceedingly diverse group of organisms whose molecular exploration is experiencing a renaissance. While the classical view of bacterial gene expression was relatively simple, the ...emerging view is more complex, encompassing extensive post-transcriptional control involving riboswitches, RNA thermometers, and regulatory small RNAs (sRNAs) associated with the RNA-binding proteins CsrA, Hfq, and ProQ, as well as CRISPR/Cas systems that are programmed by RNAs. Moreover, increasing interest in members of the human microbiota and environmental microbial communities has highlighted the importance of understudied bacterial species with largely unknown transcriptome structures and RNA-based control mechanisms. Collectively, this creates a need for global RNA biology approaches that can rapidly and comprehensively analyze the RNA composition of a bacterium of interest. We review such approaches with a focus on RNA-seq as a versatile tool to investigate the different layers of gene expression in which RNA is made, processed, regulated, modified, translated, and turned over.
RNA-seq-based approaches are revolutionizing how bacterial RNA biology can be studied. Hör, Gorski, and Vogel review the available global methods that can be used to chart the increasingly diverse number of RNA species and functions in any microbe of interest.
Dual RNA-seq of pathogen and host Westermann, Alexander J; Gorski, Stanislaw A; Vogel, Jörg
Nature reviews. Microbiology,
09/2012, Letnik:
10, Številka:
9
Journal Article
Recenzirano
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A comprehensive understanding of host-pathogen interactions requires a knowledge of the associated gene expression changes in both the pathogen and the host. Traditional, probe-dependent approaches ...using microarrays or reverse transcription PCR typically require the pathogen and host cells to be physically separated before gene expression analysis. However, the development of the probe-independent RNA sequencing (RNA-seq) approach has begun to revolutionize transcriptomics. Here, we assess the feasibility of taking transcriptomics one step further by performing 'dual RNA-seq', in which gene expression changes in both the pathogen and the host are analysed simultaneously.
Phenotypically identical cells can dramatically vary with respect to behavior during their lifespan and this variation is reflected in their molecular composition such as the transcriptomic ...landscape. Single-cell transcriptomics using next-generation transcript sequencing (RNA-seq) is now emerging as a powerful tool to profile cell-to-cell variability on a genomic scale. Its application has already greatly impacted our conceptual understanding of diverse biological processes with broad implications for both basic and clinical research. Different single-cell RNA-seq protocols have been introduced and are reviewed here-each one with its own strengths and current limitations. We further provide an overview of the biological questions single-cell RNA-seq has been used to address, the major findings obtained from such studies, and current challenges and expected future developments in this booming field.
DNA lesions interfere with DNA and RNA polymerase activity. Cyclobutane pyrimidine dimers and photoproducts generated by ultraviolet irradiation cause stalling of RNA polymerase II, activation of ...transcription-coupled repair enzymes, and inhibition of RNA synthesis. During the S phase of the cell cycle, collision of replication forks with damaged DNA blocks ongoing DNA replication while also triggering a biochemical signal that suppresses the firing of distant origins of replication. Whether the transcription machinery is affected by the presence of DNA double-strand breaks remains a long-standing question. Here we monitor RNA polymerase I (Pol I) activity in mouse cells exposed to genotoxic stress and show that induction of DNA breaks leads to a transient repression in Pol I transcription. Surprisingly, we find Pol I inhibition is not itself the direct result of DNA damage but is mediated by ATM kinase activity and the repair factor proteins NBS1 (also known as NLRP2) and MDC1. Using live-cell imaging, laser micro-irradiation, and photobleaching technology we demonstrate that DNA lesions interfere with Pol I initiation complex assembly and lead to a premature displacement of elongating holoenzymes from ribosomal DNA. Our data reveal a novel ATM/NBS1/MDC1-dependent pathway that shuts down ribosomal gene transcription in response to chromosome breaks.
Trafficking of RNA molecules and proteins within the cell nucleus is central to genome function. Recent work has revealed the nature of RNA and protein motion within the nucleus and across the ...nuclear membrane. These studies have given insight into how molecules find their destinations within the nucleus and have uncovered some of the structural properties of the nuclear microenvironment. Control of RNA and protein trafficking is now emerging as a physiological regulatory mechanism in gene expression and nuclear function.
The interaction of transcription factors with target genes is highly dynamic. Whether the dynamic nature of these interactions is merely an intrinsic property of transcription factors or serves a ...regulatory role is unknown. Here we have used single-cell fluorescence imaging combined with computational modeling and chromatin immunoprecipitation to analyze transcription complex dynamics in gene regulation during the cell cycle in living cells. We demonstrate a link between the dynamics of RNA polymerase I (RNA Pol I) assembly and transcriptional output. We show that transcriptional upregulation is accompanied by prolonged retention of RNA Pol I components at the promoter, resulting in longer promoter dwell time, and an increase in the steady-state population of assembling polymerase. As a consequence, polymerase assembly efficiency and, ultimately, the rate of entry into processive elongation are elevated. Our results show that regulation of rDNA transcription in vivo occurs via modulation of the efficiency of transcription complex subunit capture and assembly.
We are proud to announce our 2010 FOCUS ISSUE on the topic of Spatial Organization of Signalling. This editorial introduces you to the subjects that recognized experts discuss in their individual ...reviews. Sit back, read and enjoy….
We have described procedures for collecting, processing, and analyzing kinetic data obtained by photobleaching microscopy of GFP-tagged chromatin proteins in nuclei of cultured living cells. These ...procedures are useful for characterizing the in vivo binding of chromatin proteins to their natural template--unperturbed, native chromatin in an intact cell nucleus. These techniques have revealed several generalizations that significantly change our view of the nucleus. At the qualitative level, it has become clear that almost all chromatin proteins bind only transiently to their targets. More importantly, the combined use of in vivo microscopy and kinetic, computational analysis allows analysis of the kinetics of protein binding in vivo. These methods should prove useful in the further in vivo investigation of the molecular mechanisms involved in genome organization and expression.
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