Genome-wilde identification of decapping substrates in the yeast Saccharomyces cervisiae
ABSTRACT: To assess the roles of the Dcp2 C-terminal domain and the decapping activators Pat1, Lsm1, and Dhh1 in mRNA decapping, we used RNA-Seq to analyze the expression profiles of yeast cells harboring a truncation of the Dcp2 C-terminal domain, mutations that render Dcp2 catalytically inactive, or deletions of the PAT1, LSM1, and DHH1 genes. Consistent with our recent model for decapping regulation, we found that: i) the Dcp2 C-terminal domain is an effector of both negative and positive regulation and that loss of these control functions causes significant deregulation of mRNA decapping; ii) rather than being global activators of decapping, Pat1, Lsm1, and Dhh1 directly target specific subsets of yeast mRNAs and loss of the functions of each of these factors has substantial indirect consequences for genome-wide mRNA expression; and iii) transcripts targeted by Pat1, Lsm1, and Dhh1 exhibit only partial overlap and, as expected, are targeted to decapping-dependent decay. Overall design: Genome-wide expression profiles of the wild-type strain and each of the mutant strains were generated by RNA-Seq, in triplicate, using Illumina HiSeq4000. The transcripts differentially expressed in different mutant cells were identified by comparisons to the transcripts expressed in wild-type cells.
Project description:We analyzed mRNA expression profiles in Drosophila melanogaster S2 cells that had been depleted of proteins known as mRNA decapping co-activators. mRNA decapping is catalyzed by DCP2, and DCP2 activity is stimulated by decapping co-activators. This group of proteins includes DCP1, Hedls (also known as Ge-1), LSm16 (also known as EDC3), rck/p54 (also known as DHH1 or Me31B), Pat1, and the heptameric LSm1-7 complex. We used the RNA interference technology to deplete cultured S2 cells of DCP1 (CG11183), Ge-1 (CG6181), Pat1 (CG5208), LSm16 (CG6311), and LSm1 (CG4279). We used Affymetrix oligonucleotide microarrays to analyze two independent samples for each depletion. We included the following controls: mock RNAi treatment and GFP dsRNA treatment (two profiles each). We also profiled AGO1 (CG6671) depleted cells (3 independent samples). AGO1 is a key protein required for miRNA-mediated gene silencing. We had shown previously that silencing by miRNAs involves decapping of target mRNAs.
Project description:To assess the role of the decapping activator Scd6 in mRNA decay, we used RNA-Seq to analyze the expression profile of yeast cells harboring a deletion of the SCD6 gene. Consistent with our recent model for decapping regulation, we found that Scd6 targets a small number of specific mRNAs in yeast cells. Interestingly, degradation of Scd6-targeted transcripts also requires the functions of the decapping activators Pat1, Lsm1, and Dhh1, suggesting that Scd6 functions together with Pat1, Lsm1, and Dhh1 in promoting mRNA decapping. Overall design: Genome-wide expression profiles of the wild-type and scd6∆ strains were generated by RNA-Seq, in triplicate, using Illumina HiSeq4000. Transcripts differentially expressed in the scd6∆ strain were identified by comparing to the wild-type strain.
Project description:Uridylation is a widespread modification destabilizing eukaryotic mRNAs. Yet, molecular mechanisms underlying TUTase-mediated mRNA degradation remain mostly unresolved. Here, we report that the Arabidopsis TUTase URT1 participates in a molecular network connecting several translational repressors/decapping activators including DECAPPING 5 (DCP5), the Arabidopsis ortholog of human LSM14 and yeast Scd6. A conserved Helical Leucine-rich Motif (HLM) within an intrinsically disordered region of URT1 binds to the LSm domain of DCP5. This interaction connects URT1 to additional decay factors like DDX6/Dhh1-like RNA helicases. The combination of in planta and in vitro analyses supports a model that explains how URT1 reduces the accumulation of oligo(A)-tailed mRNAs: first, by connecting decapping factors and second, because 3’ terminal uridines can intrinsically hinder deadenylation. Importantly, preventing the accumulation of excessively deadenylated mRNAs in Arabidopsis avoids the biogenesis of illegitimate siRNAs that silence endogenous mRNAs and perturb plant growth and development.
Project description:Proteins regulate gene expression by controlling mRNA biogenesis, localization, translation and decay. Identifying the composition, diversity and function of mRNPs (mRNA protein complexes) is essential to understanding these processes. In a global survey of S. cerevisiae mRNA binding proteins we identified 120 proteins that cross-link to mRNA, including 66 new mRNA binding proteins. These include kinases, RNA modification enzymes, metabolic enzymes, and tRNA and rRNA metabolism factors. These proteins show dynamic subcellular localization during stress, including assembly into stress granules and P-bodies (Processing-bodies). CLIP (cross-linking and immunoprecipitation) analyses of the P-body components Pat1, Lsm1, Dhh1 and Sbp1 identified sites of interaction on specific mRNAs revealing positional binding preferences and co-assembly preferences. Taken together, this work defines the major yeast mRNP proteins, reveals widespread changes in their subcellular location during stress, and begins to define assembly rules for P-body mRNPs. CLIP-seq analysis of Dhh1, Lsm1, Pat1 and Sbp1
Project description:We report the role of LSM1-7 complex in the Arabidopsis tolerance to abiotic stresses. LSM1-7 controls gene expression reprogramming at the post-transcriptional level by promoting the decapping of mRNA. This function is selectively achieve over selected stress-induced transcripts depending on stress nature. Overall design: Comparison of transcriptomes from Col-0 and lsm1a lsm1b plants exposed to low temperatures, drought or high salt conditions
Project description:We report a function of human mRNA decapping factors in control of transcription by RNA polymerase II. Decapping proteins Edc3, Dcp1a and Dcp2 and the termination factor TTF2 co-immunoprecipitate with Xrn2, the nuclear 5'-3' exonuclease torpedo that facilitates transcription termination at the 3' ends of genes. Dcp1a, Xrn2 and TTF2 localize near transcription start sites (TSSs) by ChIP-Seq. At genes with 5' peaks of paused pol II, knockdown of decapping or termination factors, Xrn2 and TTF2, shifted polymerase away from the TSS toward upstream and downstream distal positions. This re-distribution of pol II is similar in magnitude to that caused by depletion of the elongation factor Spt5. We propose that coupled decapping of nascent transcripts and premature termination by the torpedo mechanism is a widespread mechanism that limits bidirectional pol II elongation. Regulated co-transcriptional decapping near promoter-proximal pause sites followed by premature termination could control productive pol II elongation. RNA pol II (GSE30895: GSM766171), Xrn2, TTF2 and Dcp1a were localized by ChIP-Seq in HeLa cells. RNA pol II was localized in control HEK293 cells and cells infected with lentiviruses expressing a scrambled control shRNA (scr), and shRNAs targeting the following proteins: Xrn2, TTF2, Xrn2+TTF2, Edc3, Dcp1a, and Dcp2.
Project description:The Dcp2 and Nudt16 Nudix hydrolases, are mRNA decapping enzymes that preferentially modulate stability of a subset of mRNAs. Here we report Nudt3 is a third Nudix protein that possess mRNA decapping activity in cells and is a modulator of cell migration in MCF-7 breast cancer cells. Genome-wide analysis of Nudt3 compromised cells identified increases in mRNAs involved in cell motility including integrin β6, lipocalin-2 and fibronectin. The increase in mRNA levels was dependent on Nudt3 decapping activity where integrin β6 and lipocalin-2 were modulated directly through mRNA stability, while fibronectin was indirectly controlled. Moreover, increased cell migration observed in Nudt3 depleted cells was mediated through the extracellular integrin β6 and fibronectin protein nexus. We conclude, Nudt3 is an mRNA decapping enzyme that orchestrates expression of a subset of mRNAs to modulate cell migration and further substantiates the existence of multiple decapping enzymes functioning in distinct cellular pathways in mammals. Stably transformed MCF-7 cell lines constitutively expressing either a short hairpin RNA (shRNA) directed against Nudt3 (Nudt3KD) or a non-targeted control shRNA (ConKD) were used, with three replicate cultures used per group (n=3).
Project description:This study involves the role of yeast mRNA decay factors in transcription. The experiment included here are the ChIP-exo results of three decay factors: Xrn1, Dcp2 & Lsm1. Four experiments were made: Xrn1, Dcp2, Lsm1 and control (no-TAP tag), in two replicates.
Project description:Oocyte maturation is accompanied by a transition from mRNA stability to instability. We investigated the role of DCP1A and DCP2, proteins responsible for mRNA decapping, in mRNA destabilization during mouse oocyte maturation. siRNA-mediated knockdown of both Dcp1a and Dcp2 transcripts prior to initiation of maturation inhibited the maturation-associated increase of DCP1A and DCP2, stabilized a set of maternal mRNAs that are normally degraded during maturation, and inhibited development beyond the 2-cell stage, likely a consequence of failure to activate fully the zygotic genome. Overall design: Total RNA from 30 MII eggs was used in each sample. Three independent biological replicates were analyzed for each condition.
Project description:we determined the contribution of the decapping enzyme Dcp2 to maternal mRNA clearance in zebrafish embryos by overexpressing a dominant-negative form of Dcp2. Overall design: zebrafish embryonic mRNA profile at 6 hpf in mock-inejcted or Dcp2-DN expressing embryos. Experiments are performed as triplicates.