Project description:Much of posttranscriptional mRNA regulation occurs through cis-acting sequences in mRNA 3´ untranslated regions (UTRs), which interact with specific proteins and ribonucleoprotein complexes that modulate translation, mRNA stability and subcellular localization. Studies in Caenorhabditis elegans have revealed indispensable roles for 3´UTR-mediated gene regulation, yet most C. elegans genes have lacked annotated 3´UTRs. Here we describe a high-throughput method to reliably identify 3´ ends of polyadenylated RNAs. This method, called poly(A)-position profiling by sequencing (3P-Seq), was used to determine the UTRs of C. elegans. Compared to standard methods also recently applied to C. elegans UTRs, 3P-Seq identified 8775 additional UTRs while excluding thousands of shorter UTR isoforms that do not appear to be authentic. Analysis of this expanded and corrected dataset indicated that the high A/U content of C. elegans 3´UTRs facilitated genome compaction, since the elements specifying cleavage and polyadenylation, which are A/U-rich, can more readily emerge in A/U rich regions. Indeed, 30% of the protein-coding genes have mRNAs with alternative, partially overlapping end regions that generate another 10,000 cleavage and polyadenylation sites that had gone largely unnoticed and represent potential evolutionary intermediates of progressive UTR shortening. Moreover, a third of the convergently transcribed genes utilize palindromic arrangements of bidirectional elements to specify UTRs with convergent overlap, which also contributes to genome compaction by eliminating regions between genes. Although nematode 3´UTRs have median length only one-sixth that of mammalian 3´UTRs, they have twice the density of conserved microRNA sites, in part because additional types of seed-complementary sites are preferentially conserved. These findings reveal the influence of cleavage and polyadenylation on the evolution of genome architecture and provide resources for studying posttranscriptional gene regulation. Nine samples (10 sequencing runs) from various mixed and specific stages of wild-type Caenorhabditis elegans and glp-4 mutant adults.
Project description:PolyA, Position, Profiling (3P-seq) for mouse tissues and cell lines There is no biological replicates. For six mouse tissues, 3P-seq libraries were constructed in wild-type and miR-22 knockout mouse.
Project description:Thousands of large intervening non-coding RNAs (lincRNAs) have been identified in mammals. To better understand the evolution and functions of these enigmatic RNAs, we used chromatin marks, poly(A)-site mapping and RNA-Seq data, to identify more than 550 distinct lincRNAs in zebrafish. Although these shared many characteristics with mammalian lincRNAs, only 29 had detectable sequence similarity with putative mammalian orthologs, typically restricted to a single short region of high conservation. Other lincRNAs had conserved genomic locations without detectable sequence conservation. Antisense reagents targeting conserved regions of two zebrafish lincRNAs caused developmental defects. Reagents targeting splice sites caused the same defects and were rescued by adding either the mature lincRNA or its human or mouse ortholog. Our study provides a roadmap for identification and analysis of lincRNAs in model organisms and shows that lincRNAs play crucial biological roles during embryonic development with functionality conserved despite limited sequence conservation. H3K4me3, H3K36me3 chromatin maps, 3P-Seq and RNA-Seq were used to identify lincRNAs in the zebrafish genome
Project description:The post-transcriptional fate of messenger RNAs (mRNAs) is largely dictated by their 3' untranslated regions (3'UTRs), which are defined by cleavage and polyadenylation (CPA) of pre-mRNAs. We used poly(A)-position profiling by sequencing (3P-Seq) to map poly(A) sites at eight developmental stages and tissues in the zebrafish. Analysis of over 60 million 3P-Seq reads substantially increased and improved existing 3'UTR annotations, resulting in confidently identified 3'UTRs for more than 78.79% of the annotated protein-coding genes in zebrafish. Most zebrafish genes undergo alternative CPA with more than a thousand genes using different dominant 3'UTRs at different stages. 3'UTRs tend to be shortest in the ovaries and longest in the brain. Isoforms with some of the shortest 3'UTRs are highly expressed in the ovary yet absent in the maternally contributed RNAs of the embryo, perhaps because their 3'UTRs are too short to accommodate a uridine-rich motif required for stability of the maternal mRNA. At two hours post-fertilization, thousands of unique poly(A) sites appear at locations lacking a typical polyadenylation signal, which suggests a wave of widespread cytoplasmic polyadenylation of mRNA degradation intermediates. Our insights into the identities, formation, and evolution of zebrafish 3'UTRs provide a resource for studying gene regulation during vertebrate development. 3P-Seq was used to map the 3' ends of protein-coding genes in the zebrafish genome
Project description:Methylation of cytosines (5meC) is a widespread heritable DNA modification. During mammalian development, two global demethylation events are followed by waves of de novo DNA methylation. In vivo mechanisms of DNA methylation establishment are largely uncharacterized. Here we use Saccharomyces cerevisiae as a system lacking DNA methylation to define the chromatin features influencing the activity of the murine DNMT3B. Our data demonstrate that DNMT3B and H3K4 methylation are mutually exclusive and that DNMT3B is co-localized with H3K36 methylated regions. In support of this observation, DNA methylation analysis in yeast strains without Set1 and Set2 show an increase of relative 5meC levels at the TSS and a decrease in the gene-body, respectively. We extend our observation to the murine male germline, where H3K4me3 is strongly anti-correlated while H3K36me3 correlates with accelerated DNA methylation. These results show the importance of H3K36 methylation for gene-body DNA methylation in vivo. Yeast mRNA sequencing
Project description:These datasets profile the expression of small RNAs with 3p hydroxyls (including endo-siRNAs, miRNAs, and 21U-RNAs) in young adult worms from the wt and prg-1 mutant backgrounds. They were prepared using an approach that captures small RNAs independent of the covalent status of their 5p termini, as described in Ambros et al. (2003) Curr Biol 13:807-18. These datasets were prepared in the Craig C. Mello laboratory. Keywords: endo-siRNA mutant expression profiling CE-prg1-endoSiRNAs-Illumina 1 flowcell each for the wt and prg-1 mutant
Project description:Here, we use ribosome-footprint profiing and mRNA-seq to determine the average ribosome density on each gene in S. cerevisiae. We then perform quantitative modeling to identify the molecular determinants of ribosome density. Analysis of S. cerevisiae