Project description:To examine whether the mutations in NLS1/2 affect the interaction with mRNAs, we determined the in vitro and in vivo interaction of WT Xrn1 and Xrn1 Delta NLS1/2 mutant with cellular mRNAs.
Project description:The Crabtree effect, in which fermentative metabolism is preferred at the expense of respiration, is a hallmark of budding yeast’s glucose response and a model for the Warburg effect in human tumors. While the glucose-responsive transcriptional repressors Mig1p and Mig2p play well-characterized roles in the Crabtree effect, little function for the related Mig3p transcription factor has been uncovered despite numerous investigations of laboratory yeast strains. Here we studied a wild isolate of Saccharomyces cerevisiae to uncover a critical role for Mig3p that has been lost in S288c-derived laboratory strains. We found that Mig3p affects the expression of hundreds of glucose-responsive genes in the oak strain YPS163, both during growth under standard conditions and upon ethanol treatment. Our results suggest that Mig3p may act as a multifunctional activator/repressor that plays separate roles under standard versus stress conditions, but this function has been largely lost in the lab strains. Population analysis suggests that the lab strain, and several wild strains, harbor mutations that diminish Mig3p function. Thus, by expanding our attention to multiple genetic backgrounds, we have uncovered an important missing link in a key metabolic response. We performed a series of microarray experiments comparing the gene expression response of unstressed or EtOH stressed wild-type or mig3∆ strains in either the BY4741 or YPS163 background (biological triplicates). We also compared gene expression for in reciprocal hemizygous strains (YPS163/BY4741mig3∆ and YPS163mig3∆/BY4742; biological duplicates). Lastly, we measured the gene expression of BY4741 over-expressing BY_MIG3 via galactose induction (biological triplicates).
Project description:ppGpp accumulation caused by ectopic expression of RelA in Saccharomyces cerevisiae gave rise to marked changes in gene expression with both upregulation and downregulation, including changes in mitochondrial gene expression. The most prominent upregulation (38-fold) was detected in the function-unknown hypothetical gene YBR072C-A, followed by many other known stress-responsive genes. ppGpp acuumulation resulted in enhancement of tolerance against various stress stimuli, such as osmotic stress, ethanol, hydrogen peroxide, and high temperature. A two chip study using total RNA recoverd from the Saccharomyces cerevisiae TN2080 (accumulating ppGpp) and TN2077 (vector control) grown to mid-growth phase (8h) in SC-uracil medium. The plasmid pYC2/CT (V5-epitope tag vector) was used as a vector to express Sj-RSH.
Project description:The aim of the study was to evaluate excretory-secretory protein set produced by nematode H. polygyrus L4 stage male and female developed in colitic milienu. Mass spectrometry was used to identify proteins. OmicsBox was used to investigate the functions of the discovered proteins.
Project description:The differentiation of cells into distinct cell types, each of which is heritable for many generations, underlies many biological phenomena. White and opaque cells of the fungal pathogen Candida albicans are two such heritable cell types, each thought to be adapted to unique niches within their human host. To systematically investigate the differences between the two cell types, we performed strand-specific massively-parallel sequencing of RNA from C. albicans white and opaque cells. Combining the resulting data from both cell types, we first substantially re-annotated the C. albicans transcriptome, finding 1443 novel coding and non-coding transcriptionally active regions. Using the new annotation, we compared differences in transcript abundance between the two cell types with the genomic regions bound by the master regulator of the white-opaque switch (Wor1). We found that the revised transcriptional landscape considerably alters our understanding of the circuit governing differentiation. In particular, we can now resolve the poor concordance between binding of the master regulator and the differential expression of adjacent genes, a discrepancy observed in many other studies of cell differentiation. More than one third of the Wor1-bound differentially-expressed transcripts were previously unannotated, which explains the formerly puzzling presence of Wor1 at these positions along the genome. Indeed, many of these newly identified Wor1-regulated genes are non-coding and transcribed antisense to coding transcripts. We also found that 5' and 3' untranslated regions (UTRs) of mRNAs in the circuit are unusually long and that 5' UTRs often differ in length between white and opaque cells. These observations suggest that the use of alternative promoters is widespread in the circuit and that important regulatory information is carried in the long UTRs. Further analysis revealed that the revised Wor1 circuit bears several striking similarities to the Oct4 circuit that specifies the pluripotency of mammalian embryonic stem cells. Additional characteristics shared with the Oct4 circuit suggest a set of general hallmarks characteristic of heritable differentiation states in eukaryotes. RNA-Seq was applied to Candida albicans white and opaque cells to identify novel transcripts and UTRs that are differentially regulated between the two cell types. Two biological replicates each of white and opaque cell cultures. One of the white cell RNA samples was split just after isolation to allow a comparison of the poly(A)-selection and ribo-depletion sample preparation strategies.
Project description:The aim of the project was to characterize changes in gene expression that are associated with induced autophagic flux. We engineered HeLa, HEK 293 and SH-SY5Y cell lines to express tandem-fluorecent LC3 (tf-LC3). The ratio of the red and green fluorophores indicated how much of the LC3 is in the acidic interior of lysosomes, which was a proxy measure for autophagic flux. RNA sequencing was performed for the cell lines at baseline and 1h, 15h and 30h after treatments. Additional untreated samples were also sequenced at some but not all time points. Autophagy was induced by amino acid starvation or mTOR inhibition (AZD8055).
Project description:To cause a systemic infection, Salmonella must respond to many environmental cues during mouse infection and express specific subsets of genes in a temporal and spatial manner, but the regulatory pathways are poorly established. To unravel how micro-environmental signals are processed and integrated into coordinated action, we constructed in-frame non-polar deletions of 83 regulators inferred to play a role in Salmonella enteriditis Typhimurium (STM) virulence and tested them in three virulence assays (intraperitoneal [i.p.], and intragastric [i.g.] infection in BALB/c mice, and persistence in 129X1/SvJ mice). Overall, 35 regulators were identified whose absence attenuated virulence in at least one assay, and of those, 14 regulators were required for systemic mouse infection, the most stringent virulence assay. As a first step towards understanding the interplay between a pathogen and its host from a systems biology standpoint, we focused on these 14 genes. Transcriptional profiles were obtained for deletions of each of these 14 regulators grown under four different environmental conditions. These results, as well as publicly available transcriptional profiles, were analyzed using both network inference and cluster analysis algorithms. The analysis predicts a regulatory network in which all 14 regulators control the same set of genes necessary for Salmonella to cause systemic infection. We tested the regulatory model by expressing a subset of the regulators in trans and monitoring transcription of 7 known virulence factors located within Salmonella pathogenicity island 2 (SPI-2). These experiments validated the regulatory model and showed that the response regulator SsrB and the MarR type regulator, SlyA, are the terminal regulators in a cascade that integrates multiple signals. Furthermore, experiments to demonstrate epistatic relationships showed that SsrB can replace SlyA and, in some cases, SlyA can replace SsrB for expression of SPI-2 encoded virulence factors. A total of 55 RNA pools from 14 strains in 4 conditions were prepared. An additional 12 RNA samples were prepared from the parental strain. All were subjected to microarray analysis according to the procedures described (Porwollik S et al. 2003 Nucleic Acids Res 31: 1869M-bM-^@M-^S1876). Genomic DNA from 14028s was isolated and used as reference for hybridization.
Project description:Wild-type cells and cells with abundant high-affinity transporters (PHO84C) were transferred from rich medium (SD) to medium containing 0.5mM phosphate Cells were grown to logarithmic phase in SC medium (OD=0.5), washed and then incubated in SC medium with intermediate phosphate level (0.5mM, initial OD=0.05). During the experiment (0, 1, 5, 8 and 23 hours) cells were harvested, pelleted and frozen for further analysis. Total RNA was extracted using MasterPure™fication Kit (Epicentre). The samples were amplified, labeled, hybridized to yeast dual color expression microarrays and scanned, all using standard Agilent protocols, reagents, and instruments. The scanned images were analyzed using SpotReader software (Niles Scientific).
Project description:A universal feature of the response to stress and nutrient limitation is transcriptional upregulation of genes encoding proteins important for survival. Interestingly, under many of these conditions overall protein synthesis levels are reduced, thereby dampening the stress response at the level of protein expression. For example, during glucose starvation in yeast, translation is rapidly and reversibly repressed, yet transcription of many stress- and glucose-repressed genes is increased. Using ribosome profiling and microscopy, we found that this transcriptionally upregulated gene set consists of two classes: (1) one producing mRNAs that are preferentially translated during glucose limitation and are diffusely localized in the cytoplasm – this class includes many heat shock protein mRNAs; and (2) another producing mRNAs that are poorly translated during glucose limitation, have high rates of translation initiation, and are concentrated in foci that co-localize with P bodies and stress granules – this class is enriched for glucose metabolism mRNAs. Remarkably, the information specifying differential localization and translation of these two classes of mRNAs is encoded in the promoter sequence – promoter responsiveness to heat shock factor (Hsf1) specifies diffuse cytoplasmic localization and preferential translation upon glucose starvation, whereas different promoter elements upstream of genes encoding poorly translated glucose metabolism mRNAs direct these mRNAs to RNA granules under glucose starvation. Thus, promoter sequences and transcription factor binding can influence not only mRNA levels, but also subcellular localization of mRNAs and the efficiency with which they are translated, enabling cells to tailor protein production to environmental conditions. Examination of mRNA translation in S. cerevisiae upon glucose starvation.
Project description:Comparative Dynamic Transcriptome Analysis (cDTA) enables global analysis of newly synthesized RNA as described in Sun et al. Genome Res. 2012 (DOI:10.1101/gr.130161.111) and reveals defects in transcription with much higher sensitivity than conventional steady-state methods. cDTA was carried out as described in Sun et al. Genome Res. 2012 (DOI:10.1101/gr.130161.111), using the S. cerevisiae heterozygous Med17/med17delta strain (Euroscarf) transfected with plasmids pRS315-SRB4 or pRS315-srb4-ts as described in Larivi̬re et al. Nature. 2012 (DOI:10.1038/nature11670), and Y40343-wildtype (Euroscarf) or Med18-FRB-KanMX6 (Euroscarf) strains. Heatshock of SRB4 and srb4-ts strains was applied for 18 or 60 minutes at 37C prior to RNA labeling as described in Sun et al. Genome Res. 2012 (DOI:10.1101/gr.130161.111). To deplete the Med18 subunit from the nucleus, anchor-away experiments were performed by rapamycin treatment (1 ug/ml in 200 mL YPD) for 18 or 60 minutes at 30C prior to RNA labeling as described in Sun et al. Mol. Cell. 2013 (DOI:10.1016/j.molcel.2013.09.010). Data analysis was as described in Sun et al. Genome Res. 2012 (DOI:10.1101/gr.130161.111).