Dataset Information

Post-transcriptional regulation in the myo1? mutant of Saccharomyces cerevisiae.

ABSTRACT: Saccharomyces cerevisiae myosin type II-deficient (myo1?) strains remain viable and divide, despite the absence of a cytokinetic ring, by activation of the PKC1-dependent cell wall integrity pathway (CWIP). Since the myo1? transcriptional fingerprint is a subset of the CWIP fingerprint, the myo1? strain may provide a simplified paradigm for cell wall stress survival.To explore the post-transcriptional regulation of the myo1? stress response, 1,301 differentially regulated ribosome-bound mRNAs were identified by microarray analysis of which 204 were co-regulated by transcription and translation. Four categories of mRNA were significantly affected - protein biosynthesis, metabolism, carbohydrate metabolism, and unknown functions. Nine genes of the 20 CWIP fingerprint genes were post-transcriptionally regulated. Down and up regulation of selected ribosomal protein and cell wall biosynthesis mRNAs was validated by their distribution in polysomes from wild type and myo1? strains. Western blot analysis revealed accumulation of the phosphorylated form of eukaryotic translation initiation factor 2 (eIF2?-P) and a reduction in the steady state levels of the translation initiation factor eIF4Gp in myo1? strains. Deletion of GCN2 in myo1? abolished eIF2?p phosphorylation, and showed a severe growth defect. The presence of P-bodies in myo1? strains suggests that the process of mRNA sequestration is active, however, the three representative down regulated RP mRNAs, RPS8A, RPL3 and RPL7B were present at equivalent levels in Dcp2p-mCh-positive immunoprecipitated fractions from myo1? and wild type cells. These same RP mRNAs were also selectively co-precipitated with eIF2?-P in myo1? strains.Quantitative analysis of ribosome-associated mRNAs and their polyribosome distributions suggests selective regulation of mRNA translation efficiency in myo1? strains. Inhibition of translation initiation factor eIF2? (eIF2?-P) in these strains was by Gcn2p-dependent phosphorylation. The increase in the levels of eIF2?-P; the genetic interaction between GCN2 and MYO1; and the reduced levels of eIF4Gp suggest that other signaling pathways, in addition to the CWIP, may be important for myo1? strain survival. Selective co-immunoprecipitation of RP mRNAs with eIF2?-P in myo1? strains suggests a novel mode of translational regulation. These results indicate that post-transcriptional control is important in the myo1? stress response and possibly other stresses in yeast.

SUBMITTER: Rivera-Ruiz ME

PROVIDER: S-EPMC3017085 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Post-transcriptional regulation in the myo1Δ mutant of Saccharomyces cerevisiae.

Rivera-Ruiz Marielis E ME Rodríguez-Quiñones José F JF Akamine Pearl P Rodríguez-Medina José R JR

BMC genomics 20101202

<h4>Background</h4>Saccharomyces cerevisiae myosin type II-deficient (myo1Δ) strains remain viable and divide, despite the absence of a cytokinetic ring, by activation of the PKC1-dependent cell wall integrity pathway (CWIP). Since the myo1Δ transcriptional fingerprint is a subset of the CWIP fingerprint, the myo1Δ strain may provide a simplified paradigm for cell wall stress survival.<h4>Results</h4>To explore the post-transcriptional regulation of the myo1Δ stress response, 1,301 differentiall ...[more]

PMID: 21126371

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Project description:The microarrays experiments of three biological and one technical replicates were performed in YJR12 (wt) and YJR13 (myo1∆) strains. YJR12 (wild type) and YJR13 (myo1∆) strains were obtained as haploid segregants from a cross between YJR6 (myo1::HIS5 strain) and BY4741 (obtained from ATTC). Cultures were grown overnight at 26ºC to an optical density between 0.5-0.8 (OD600) in complete synthetic media (CSM, 2% glucose, 1X Nitrogen base) with continuous shaking at 200 rpm. RNA was extracted from ribosomal pellets using the RNeasy Mini Kit (Qiagen, Valencia, CA) following the manufacturer’s instructions. RNA concentrations were determined by measuring absorbance at 260nm using a Nanodrop spectrophotometer (Nanodrop Technologies). The purity and integrity of the RNA was monitored using an Agilent Bioanalyzer (Agilent Technologies) following the manufacturer’s instructions. 1.0 µg of RNA extracted form ribosomal pellets from each sample was amplified using the Low RNA Input Fluorescent Linear Amplification kit (Agilent Technologies). The amplified cRNA was labeled with 10mM Cyanine 5-CTP (Cy5) or Cyanine 3-CTP (Cy3) (Perkin Elmer Life Sciences). Labeled cRNA’s were purified with Qiagen RNeasy mini spin columns and dye incorporation was monitored on an Agilent Bioanalyzer. Hybridization of Cy5 and Cy3 labeled cRNA’s were performed using Yeast Oligo Microarray slides and hybridization kit from Agilent Technologies (Sheldon Manufacturing) at 60ºC for 17 hours. Slides were washed and scanned with a VersArray Chip Reader system (BioRad, Hercules, CA) at a resolution of 5mm with detector sensitivity values between 704-800 and laser power at 85%. Scanned images were transferred to the Imagene 3.0 software (Biodiscovery) for further analysis to locate spots, adjust the appropriate grid, and obtain the Cy3 and Cy5 TIFF files. The microarrays raw data generated with Imagene 3.0 were analyzed using Limma software (Bioconductor Package 1.7). The data was prepared for analysis by correcting for background intensity. The individual data sets were normalized using the locally weighted linear regression (Lowess) within each array. After normalization, the difference between the experimental and control signal was calculated, replicates were combined, and their averages were calculated. The fold change in gene expression was calculated by 2^(M), where M is the log2-fold change after background correction and normalization. An Empirical Bayes Statistics for differential expression analysis (eBayes statistics) was performed by Limma. Genes with a p-value ≤ 0.018 were established as a cutoff for differential expression. In addition, a false discovery rate (FDR) test was performed by Limma program.

Project description:The microarrays experiments of three biological and one technical replicates were performed in YJR12 (wt) and YJR13 (myo1?) strains. YJR12 (wild type) and YJR13 (myo1?) strains were obtained as haploid segregants from a cross between YJR6 (myo1::HIS5 strain) and BY4741 (obtained from ATTC). Cultures were grown overnight at 26ºC to an optical density between 0.5-0.8 (OD600) in complete synthetic media (CSM, 2% glucose, 1X Nitrogen base) with continuous shaking at 200 rpm. RNA was extracted from ribosomal pellets using the RNeasy Mini Kit (Qiagen, Valencia, CA) following the manufacturer’s instructions. RNA concentrations were determined by measuring absorbance at 260nm using a Nanodrop spectrophotometer (Nanodrop Technologies). The purity and integrity of the RNA was monitored using an Agilent Bioanalyzer (Agilent Technologies) following the manufacturer’s instructions. 1.0 µg of RNA extracted form ribosomal pellets from each sample was amplified using the Low RNA Input Fluorescent Linear Amplification kit (Agilent Technologies). The amplified cRNA was labeled with 10mM Cyanine 5-CTP (Cy5) or Cyanine 3-CTP (Cy3) (Perkin Elmer Life Sciences). Labeled cRNA’s were purified with Qiagen RNeasy mini spin columns and dye incorporation was monitored on an Agilent Bioanalyzer. Hybridization of Cy5 and Cy3 labeled cRNA’s were performed using Yeast Oligo Microarray slides and hybridization kit from Agilent Technologies (Sheldon Manufacturing) at 60ºC for 17 hours. Slides were washed and scanned with a VersArray Chip Reader system (BioRad, Hercules, CA) at a resolution of 5mm with detector sensitivity values between 704-800 and laser power at 85%. Scanned images were transferred to the Imagene 3.0 software (Biodiscovery) for further analysis to locate spots, adjust the appropriate grid, and obtain the Cy3 and Cy5 TIFF files. The microarrays raw data generated with Imagene 3.0 were analyzed using Limma software (Bioconductor Package 1.7). The data was prepared for analysis by correcting for background intensity. The individual data sets were normalized using the locally weighted linear regression (Lowess) within each array. After normalization, the difference between the experimental and control signal was calculated, replicates were combined, and their averages were calculated. The fold change in gene expression was calculated by 2^(M), where M is the log2-fold change after background correction and normalization. An Empirical Bayes Statistics for differential expression analysis (eBayes statistics) was performed by Limma. Genes with a p-value ? 0.018 were established as a cutoff for differential expression. In addition, a false discovery rate (FDR) test was performed by Limma program. Previous analysis of global mRNA expression in Saccharomyces cerevisiae myosin type II deficient strains (myo1?) revealed 547 genes related to the stress response that were proposed to be regulated at the transcriptional level. The objective of this study is to explore the post-transcriptional regulation of the stress response in these strains. We have identified 1,271 differentially regulated mRNAs bound to ribosomes extracted from myo1? strains compared to wild type controls. To assess the mode of regulation of these putative translationally regulated genes, ribosomal protein (RP) mRNAs were analyzed for their polysomal distribution in sucrose gradient fractions of myo1? and wild-type (wt) cells. Our analysis of three representative RP mRNAs showed that RPS8A, RPL7B and RPL3 were recruited from heavy to lighter polyribosome fractions in myo1?, suggesting that these RP mRNAs were less efficiently translated. Western blot analysis revealed accumulation of the phosphorylated form of eukaryotic translation initiation factor 2 (eIF2?-P) in myo1? strains and RPS8A, RPL7B and RPL3 mRNAs were found co-precipitated with immunoprecipitated eIF2?-P, suggesting a direct association between eIF2?-P and translationally regulated RP mRNAs. In yeast, GCN2 codes for the only eIF2? kinase that is directly regulated by TOR (target of rapamycin) pathway. Repression of TOR by rapamycin in a myo1? strain did not increase levels of eIF2?-P yet, a gcn2?myo1? strain exhibited a severe synthetic growth defect suggesting an important survival role for TOR mediated translational regulation in these strains. Reduced steady state levels of the translation initiation factor eIF4G, were also observed in myo1? further supporting the regulation of translation by the TOR pathway. These findings support the conclusion that post-transcriptional control specifically by translation inhibition is a key component of the stress response in yeast.

Dataset Information

Post-transcriptional regulation in the myo1? mutant of Saccharomyces cerevisiae.

Publications

Post-transcriptional regulation in the myo1Δ mutant of Saccharomyces cerevisiae.

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