[PDF] Regulation Of Alternative Splicing In Drosophila eBook

Author : Philippe Jeanteur
Publisher : Springer Science & Business Media
Page : 254 pages
File Size : 12,84 MB
Release : 2013-03-14
Category : Science
ISBN : 3662097281

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The discovery in 1977 that genes are split into exons and introns has done away with the one gene - one protein dogma. Indeed, the removal of introns from the primary RNA transcript is not necessarily straightforward since there may be optional pathways leading to different messenger RNAs and consequently to different proteins. Examples of such an alternative splicing mechanism cover all fields of biology. Moreover, there are plenty of occurrences where deviant splicing can have pathological effects. Despite the high number of specific cases of alternative splicing, it was not until recently that the generality and extent of this phenomenon was fully appreciated. A superficial reading of the preliminary sequence of the human genome published in 2001 led to the surprising, and even deceiving to many scientists, low number of genes (around 32,000) which contrasted with the much higher figure around 150,000 which was previously envisioned. Attempts to make a global assessment of the use of alternative splicing are recent and rely essentially on the comparison of genomic mRNA and EST sequences as reviewed by Thanaraj and Stamm in the first chapter of this volume. Most recent estimates suggest that 40-60% of human genes might be alternatively spliced, as opposed to about 22% for C. elegans.

Author : Jefferson Matthew Taliaferro
Publisher :
Page : 167 pages
File Size : 12,73 MB
Release : 2012
Category :
ISBN :

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The patterns and mechanisms by which eukaryotic cells regulate the expression of their genetic information are highly complex and intricate. The transmittance of this information from nuclear repository to cytoplasmic translation contains within it several steps, including the selective removal and concomitant joining of pieces of information in a process called alternative splicing. The projects detailed within this document describe the regulation of alternative splicing through the interaction of specific proteins with specific pre-mRNA transcripts. The Rio lab has studied PSI, a protein involved in the regulation of the P element transposase transcript, for many years. It has since been shown to regulate the splicing of hundreds of other transcripts. The experiments described here look at the organization of PSI and other proteins on the P element transcript by site-specific labeling of the transcript using radioactive 32P. We also investigate two phosphorylation events of PSI, identifying the kinases responsible and demonstrate that these events may change the protein-protein interaction partners of PSI. It has become increasingly apparent that alternative splicing may not only be regulated by protein/RNA interactions, but also by RNA/RNA interactions. To probe this, we designed experiments to test if some well-known small RNA-associated proteins are regulating alternative splicing. Using splice junction microarrays, we determined that Argonaute-2 (Ago-2) regulated the splicing of over 100 splice junctions, and further experiments using ChIP-seq and mRNA-seq of Ago-2 mutants revealed that Ago-2 also has a role in transcriptional repression, possibly through being incorporating in complexes composed of polycomb-group genes. We also used CLIP-seq to determine the RNA binding profile and preferences of Ago-2 in Drosophila tissue culture cells. Finally, we characterized the functions of a Drosophila specific splicing factor called LS2. LS2 is orthologous to the highly conserved splicing factor dU2AF50, but its origin through retroduplication and subsequent divergence to acquire distinct sequence specificity, expression pattern, and function show it to be an interesting case in the evolution of alternative splicing regulation. This may be a mechanism that underlies the existence of some members of the large families of splicing factors, including hnRNP proteins and SR proteins. That is, by duplicating functional copies of genes, cellular systems create new proteins to tinker with and acquire new functions while keeping the former functionality and stability of the parent protein. While these projects are essentially independent of each other, they all fall under the umbrella of protein regulation of RNA metabolism and hopefully contribute to a more complete understanding of the regulation of gene expression.

Author : Benjamin J. Blencowe
Publisher : Springer Science & Business Media
Page : 260 pages
File Size : 18,27 MB
Release : 2008-01-23
Category : Medical
ISBN : 9780387773735

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Yet again Springer has reached the market before everyone. This is the first book that is solely dedicated to the topic of alternative splicing. The book contains chapters by experts in the field that cover nearly all aspects of this hugely important subject. The purpose of the text is to provide a single, authoritative source of information on alternative splicing that is accessible to researchers in diverse fields. It is suitable for beginners and experts alike.

Author :
Publisher :
Page : 10 pages
File Size : 27,7 MB
Release : 2015
Category :
ISBN :

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Alternative splicing is regulated by RNA binding proteins (RBPs) that recognize pre-mRNA sequence elements and activate or repress adjacent exons. Here, we used RNA interference and RNA-seq to identify splicing events regulated by 56 Drosophila proteins, some previously unknown to regulate splicing. Nearly all proteins affected alternative first exons, suggesting that RBPs play important roles in first exon choice. Half of the splicing events were regulated by multiple proteins, demonstrating extensive combinatorial regulation. We observed that SR and hnRNP proteins tend to act coordinately with each other, not antagonistically. We also identified a cross-regulatory network where splicing regulators affected the splicing of pre-mRNAs encoding other splicing regulators. In conclusion, this large-scale study substantially enhances our understanding of recent models of splicing regulation and provides a resource of thousands of exons that are regulated by 56 diverse RBPs.

Author : Angela Norie Brooks
Publisher :
Page : 236 pages
File Size : 26,65 MB
Release : 2011
Category :
ISBN :

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A majority of metazoan genes contain introns in their primary transcripts (pre-mRNA) that require removal by the spliceosome--a cellular complex composed of protein and RNA. Upon removal of introns from the primary transcript, the remaining exonic portion of the transcript is spliced together. It is essential to remove the correct intronic portion of a primary transcript in order to produce the desired product, typically a protein-coding mRNA. Pre-mRNAs are alternatively spliced when different intron boundaries are used by the spliceosome, thus creating different mRNA products. Alternative splicing allows for an additional step of gene regulation by producing transcript isoforms that can be differentially processed in a particular tissue or developmental time point. Alternative splicing is primarily regulated by RNA binding proteins that bind to pre-mRNA and act to recruit or inhibit the spliceosome at specific splice sites. A central aim of this work is to gain a better understanding of splicing regulation by the identification and characterization of protein regulators of splicing and cis-acting splicing regulatory sequences in the model organism, Drosophila melanogaster. To identify splicing regulatory elements, many previous studies in vertebrate genomes have used computational methods. In collaboration with Anna I. Podgornaia, I applied such an approach to predict splicing regulatory elements in Drosophila melanogaster and compared them with elements found in vertebrates. I identified 330 putative splicing enhancer sequences enriched near weak 5' and 3' splice sites of constitutively spliced introns. I found that a significant proportion (58%) of D. melanogaster enhancers were previously reported as splicing enhancers in vertebrates. To provide additional evidence for the function of the intronic splicing enhancers (ISEs), I identified intronic hexamers significantly enriched within sequences phylogenetically conserved among 15 insect species. This analysis uncovered 73 putative ISEs that are also enriched in conserved regions of the D. melanogaster genome. The functions of nine enhancer sequences were verified in a heterologous splicing reporter by Julie L. Aspden, demonstrating that these sequences are sufficient to enhance splicing in vivo. Taken together, these data identify a set of predicted positive-acting splicing regulatory motifs in the Drosophila genome and highlight those regulatory sequences that are present in distant metazoan genomes. To identify and characterize splicing regulators, collaborators and I have combined RNAi and RNA-Seq to identify exons that are regulated by 58 known or putative splicing regulators. To identify and quantify alternative splicing events from RNA-Seq data, I developed the JuncBASE (Junction Based Analysis of Splicing Events) software package. For a pilot study, I identified 404 splicing events significantly affected upon depletion of pasilla. Preliminary analysis showed 879 splicing events affected by at least one of the 57 other proteins. The sequence regions upstream and within Pasilla-repressed exons and downstream of Pasilla-activated exons are enriched for YCAY repeats, which is consistent with the location of these motifs near regulated exons of the mammalian ortholog, Nova. Thus, the RNA regulatory map of Pasilla and Nova is highly conserved between insects and mammals despite the fact that the pre-mRNAs that are regulated by Pasilla and Nova are almost entirely non-overlapping. This observation strongly suggests that the regulatory codes of individual RNA binding proteins are nearly immutable, yet the regulatory modules controlled by these proteins are highly evolvable. I also present RNA regulatory maps for the four hnRNP proteins: hrp36, hrp38, hrp40, and hrp48. Lastly, I examine splicing regulation throughout the life cycle of D. melanogaster. Using transcriptome data from 30 developmental time points produced by collaborators from the modENCODE Consortium, I identified a total of 23,859 alternative splicing events in Drosophila, taking into account all transcript information from D. melanogaster annotations, short sequenced reads (Illumina RNA-Seq), sequenced cDNA, long RNA-Seq reads (454 RNA-Seq) from adult flies, and short read sequences of rRNA-depleted RNA from embryonic time points. I observed that 60.7% of intron-containing genes in D. melanogaster are alternatively spliced. Using only the Illumina RNA-Seq reads throughout development, 21,216 splicing events were expressed and 13,951 events were differentially spliced in at least one time point. I also observed exons with similar patterns of splicing changes throughout development as well as sex-biased alternative splicing. Integrating information from our pasilla study, I also observed correlations of pasilla gene expression with alternative splicing changes of its target exons throughout development.

Author : Adrian Krainer
Publisher : IRL Press
Page : 408 pages
File Size : 30,26 MB
Release : 1997
Category : Language Arts & Disciplines
ISBN :

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This volume focuses on the major aspects of post-transcriptional mRNA processing in the nucleus of eukaryotic cells. Each of the described mRNA reactions is required for proper gene expression and can also serve as a control point for regulating the expression of many genes, for example duringembryonic development or in different cell types. The different chapters review the assembly of newly synthesized nuclear mRNA transcripts into hnRNP particles and catalytically active spliceosomes; the structure and mechanism of action of small nuclear ribonucleoprotein particles and proteinfactors that catalyse pre-mRNA splicing in mammalian cells and in yeast; the regulation of gene expression and generation of protein isoform diversity by alternative splicing; the mechanisms of 3' end cleavage and polyadenylation; the architecture of the cell nucleus in relation to these processesand to the localization of the relevant substrates and factors; the diverse mechanisms of RNA processing by ribozymes and their potential relevance for nuclear mRNA processing; the mechanism of spliced-leader addition by trans-splicing in nematodes and trypanosomes; and the process ofinsertion/deletion mRNA editing in kinetoplasmid protozoa. In each chapter, leading researchers have provided detailed, critical reviews of the history, experimental approaches, major advances, current ideas and models, as well as future directions, for each of these active areas of research.

Author : Philippe Jeanteur
Publisher : Springer Science & Business Media
Page : 265 pages
File Size : 31,78 MB
Release : 2006-10-04
Category : Science
ISBN : 3540344497

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Splicing of primary RNA transcript is a quasi-systematic step of gene expression in higher organisms. This is the first book to highlight the medical implications, i.e. diseases, caused by alternative splicing. Alternative splicing not only vastly increases protein diversity but also offers numerous opportunities for aberrant splicing events with pathological consequences. The book also outlines possible targets for therapy.