Project description:P-bodies (PB) are cytoplasmic RNP complexes that aggregate into foci when cells are exposed to stress. While the core components and stress response of PB and related RNP granules are conserved, it remains unclear how and why cells assemble mRNP complexes into granule foci during stress. We use mass spectrometry and antibody-based microarray to analyze proteins and RNA, respectively, that are immunoisolated with the core PB protein Dhh1-GFP. Analysis of the RNA associated with Dhh1-GFP immunoisolate reveals an enrichment of mitochondrial catalytic RNPs complex, suggesting a role for PB in mitochondrial RNA processing.
Project description:P-bodies (PB) are cytoplasmic RNP complexes that aggregate into foci when cells are exposed to stress. While the core components and stress response of PB and related RNP granules are conserved, it remains unclear how and why cells assemble mRNP complexes into granule foci during stress. We use mass spectrometry and antibody-based microarray to analyze proteins and RNA, respectively, that are immunoisolated with the core PB protein Dhh1-GFP. Analysis of the RNA associated with Dhh1-GFP immunoisolate reveals an enrichment of mitochondrial catalytic RNPs complex, suggesting a role for PB in mitochondrial RNA processing. RNA from 7 anti-GFP immunoisolations as well as total (input) RNA for each experiment was prepared. The seven samples include one mock IP from a strain containing GFP alone as well as 6 from Dhh1-GFP strains, two replicates from a (+) glucose condition and four replicates from a (-) glucose condition in which Dhh1-GFP forms cytoplasmic foci. 5ug of total RNA and 200ng IP RNA was hybridized to cutsom Agilent microarrays and detected using the S9.6 monoclonal antibody to RNA:DNA hybrids (ATCC clone ) and a Cy3 labeled anti-mouse secondary antibody.
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:Previous experiments revealed that DHH1, a RNA helicase involved in the regulation of mRNA stability and translation, complemented the phenotype of a Saccharomyces cerevisiae mutant affected in the expression of genes coding for monocarboxylic-acids transporters, JEN1 and ADY2. In wild type cells, JEN1 expression had been shown to be undetectable in the presence of glucose or formic acid, and induced in the presence of lactate. In this work, we show that JEN1 mRNA accumulates in a dhh1 mutant, when formic acid was used as sole carbon source. Dhh1 interacts with the decapping activator Dcp1 and with the deadenylase complex. This led to the hypothesis that JEN1 expression is post-transcriptionally regulated by Dhh1 in formic acid. Analyses of JEN1 mRNAs decay in wild-type and dhh1 mutant strains confirmed this hypothesis. Microarray analyses of dhh1 mutant indicated that Dhh1 plays a large role in metabolic adaptation, suggesting that carbon source changes triggers a complex interplay between transcriptional and post-transcriptional effects. We compared gene expression between wild type and dhh1 deleted yeast strains grown either with formate or in glucose as sole carbon source. The experiments were replicated using biologically independant samples with dye swap. A total of four hybridizations were performed.
Project description:We have developed the HRS-seq method (High-salt Recovered Sequences-sequencing), a straightforward genome-wide approach whereby we isolated and sequenced genomic regions associated with large high-salt insoluble RNP complexes. Using mouse embryonic stem cells (ESC), we showed that HRS are over-represented into the active A chromosomal compartment. The vast majority of HRS-associated genes are very highly expressed. They include both cell type-specific genes, like pluripotency genes, and housekeeping genes, like histone and snRNA genes that are central components of Histone Locus Bodies and Cajal bodies. We conclude that large, high-salt insoluble, RNP complexes including nuclear bodies are associated to the active A chromosomal compartment.
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.
Project description:Previous experiments revealed that DHH1, a RNA helicase involved in the regulation of mRNA stability and translation, complemented the phenotype of a Saccharomyces cerevisiae mutant affected in the expression of genes coding for monocarboxylic-acids transporters, JEN1 and ADY2. In wild type cells, JEN1 expression had been shown to be undetectable in the presence of glucose or formic acid, and induced in the presence of lactate. In this work, we show that JEN1 mRNA accumulates in a dhh1 mutant, when formic acid was used as sole carbon source. Dhh1 interacts with the decapping activator Dcp1 and with the deadenylase complex. This led to the hypothesis that JEN1 expression is post-transcriptionally regulated by Dhh1 in formic acid. Analyses of JEN1 mRNAs decay in wild-type and dhh1 mutant strains confirmed this hypothesis. Microarray analyses of dhh1 mutant indicated that Dhh1 plays a large role in metabolic adaptation, suggesting that carbon source changes triggers a complex interplay between transcriptional and post-transcriptional effects.
Project description:Stress granules (SGs) and processing bodies (PBs) are membraneless cytoplasmic assemblies regulating mRNAs under environmental stress such as viral infections, neurological disorders, or cancer. Upon antigen stimulation, T lymphocytes mediate their immune functions under regulatory mechanisms involving SGs and PBs. However, the impact of T cell activation on such complexes, in term of formation, constitution and relationship remains unknown. Here, by combining proteomic, transcriptomic and immunofluorescence approaches, we simultaneously characterized the SGs and PBs from primary human T lymphocytes pre- and post-stimulation. The proteomes and transcriptomes of SGs and PBs were identified, unveiling an unanticipated molecular and functional complementarity. Notwithstanding, these granules keep distinct spatial organizations and abilities to interact with mRNAs. This comprehensive characterization of the RNP granule proteomic and transcriptomic landscapes provides a unique resource for future investigations on SGs and PBs in T lymphocytes.
Project description:The impact of RNA structures in coding sequences (CDS) within mRNAs is poorly understood. Here we identify a novel and highly conserved mechanism of translational control involving RNA structures within coding sequences and the DEAD-box helicase Dhh1. Using yeast genetics and genome-wide ribosome profiling analyses we show that this mechanism, initially derived from studies of the Brome Mosaic virus RNA genome, extends to yeast and human mRNAs highly enriched in membrane and secreted proteins. All Dhh1-dependent mRNAs, viral and cellular, share key common features. First, they contain long and highly structured CDSs, including a region located around 42 to 120 nucleotides after the translation initiation site, second, they are directly bound by Dhh1 with a specific binding distribution and third, complementary experimental approaches suggest that they are activated by Dhh1 at the translation initiation step. Our results show that ribosome translocation is not the only unwinding force of CDS and uncover a conserved layer of translational control that involve RNA helicases and RNA folding within CDS providing novel opportunities for regulation of membrane and secretome proteins.