Project description:Gene expression in Eukaryotic cells is profoundly shaped by the post-transcriptional processing of mRNAs, including the splicing of introns in the nucleus and both nuclear and cytoplasmic degradation pathways. Here we report the use of a splicing isoform specific microarray platform to investigate the effects of a host of diverse stress conditions on both splicing pre-mRNA fate. Interestingly, We find that diverse stresses cause distinct patterns of changes at the level of pre- mRNA processing. The responses we observed are most dramatic for the RPGs and can be categorized into three major classes. The first is characterized by accumulation of RPG pre-mRNA and is seen in multiple types of amino acid starvation regimes; the magnitude of splicing inhibition correlates with the severity of the stress. The second class is characterized by a rapid decrease in both pre- and mature RPG mRNA and is seen in many stresses that inactivate the TORC1 kinase complex. These decreases depend on nuclear turn-over of the intron-containing pre-RNAs. The third class is characterized by a decrease in RPG pre-mRNA with only a modest reduction in the mature species; this response is observed in hyperosmotic and cation-toxic stresses. We show that casein kinase 2 (CK2) makes important contributions to the changes in pre-mRNA processing, particularly for the first two classes of stress responses. In total, our data suggest that complex post-transcriptional programs cooperate to fine-tune expression of intron-containing transcripts in budding yeast. Splicing-specific microarrays were used to assay the changes to splicing caused by a wide variety of environmental stresses and nutrient conditions.
Project description:Gene expression in Eukaryotic cells is profoundly shaped by the post-transcriptional processing of mRNAs, including the splicing of introns in the nucleus and both nuclear and cytoplasmic degradation pathways. Here we report the use of a splicing isoform specific microarray platform to investigate the effects of a host of diverse stress conditions on both splicing pre-mRNA fate. Interestingly, We find that diverse stresses cause distinct patterns of changes at the level of pre- mRNA processing. The responses we observed are most dramatic for the RPGs and can be categorized into three major classes. The first is characterized by accumulation of RPG pre-mRNA and is seen in multiple types of amino acid starvation regimes; the magnitude of splicing inhibition correlates with the severity of the stress. The second class is characterized by a rapid decrease in both pre- and mature RPG mRNA and is seen in many stresses that inactivate the TORC1 kinase complex. These decreases depend on nuclear turn-over of the intron-containing pre-RNAs. The third class is characterized by a decrease in RPG pre-mRNA with only a modest reduction in the mature species; this response is observed in hyperosmotic and cation-toxic stresses. We show that casein kinase 2 (CK2) makes important contributions to the changes in pre-mRNA processing, particularly for the first two classes of stress responses. In total, our data suggest that complex post-transcriptional programs cooperate to fine-tune expression of intron-containing transcripts in budding yeast.
Project description:We explored genomic expression patterns in the yeast Saccharomyces cerevisiae responding to diverse environmental transitions. DNA microarrays were used to measure changes in transcript levels over time for almost every yeast gene, as cells responded to temperature shocks, hydrogen peroxide, the superoxide-generating drug menadione, the sulfhydryl-oxidizing agent diamide, the disulfide-reducing agent dithiothreitol, hyper- and hypo-osmotic shock, amino acid starvation, nitrogen source depletion, and progression into stationary phase. A large set of genes (approximately 900) showed a similar drastic response to almost all of these environmental changes. Additional features of the genomic responses were specialized for specific conditions. Promoter analysis and subsequent characterization of the responses of mutant strains implicated the transcription factors Yap1p, as well as Msn2p and Msn4p, in mediating specific features of the transcriptional response, while the identification of novel sequence elements provided clues to novel regulators. Physiological themes in the genomic responses to specific environmental stresses provided insights into the effects of those stresses on the cell. Study is described in more detail in Gasch AP et al.(2000) Mol Biol Cell 11:4241-57 Keywords: other
2002-02-12 | GSE18 | GEO
Project description:Examining the common adaptive responses of Candida glabrata to diverse environmental stresses.
Project description:AP-1 like transcription factors play evolutionarily conserved roles in oxidative stress responses as redox sensors in eukaryotes. In this study, we aim to elucidate the regulatory mechanism of an atypical yeast AP-1 like protein, Yap1, in the stress response and virulence of Cryptococcus neoformans. YAP1 expression was induced not only by oxidative stresses, such as H2O2 and diamide, but also by other environmental stresses, such as osmotic and membrane destabilizing stresses. Supporting these data, Yap1 was involved in osmotic and membrane stress responses as well as oxidative stress responses. Pleiotropic roles of Yap1 in diverse biological processes were supported by transcriptome analysis data showing that more than 162 genes are differentially regulated by Yap1. This analysis also provided a clue that Yap1 is involved in carbohydrate metabolism and indeed we found that Yap1 promotes cellular resistance to toxic cellular metabolites produced during glycolysis, such as methylglyoxal. Finally, we demonstrated that Yap1 played a minor role in survival of C. neoformans within hosts.
Project description:Cells are in constant adaptation to environmental changes to insure their proper functioning. When exposed to stresses, cells activate specific pathways to elicit adaptive modifications. Those changes can be mediated by selective modulation of gene and protein expression as well as by post-translational modifications, such as phosphorylation and proteolytic processing. Protein cleavage, as a controlled and limited post-translational modification, is involved in diverse physiological processes such as the maintenance of protein homeostasis, activation of repair pathways, apoptosis and the regulation of proliferation. Here we assessed by quantitative proteomics the proteolytic landscape in two cell lines subjected to low cisplatin concentrations used as a mild non-lethal stress paradigm. This landscape was compared to the one obtained in the same cells stimulated with cisplatin concentrations inducing apoptosis. These analyses were performed in wild-type cells and in cells lacking the two main executioner caspases: caspase-3 and caspase-7. Ninety proteins were found to be cleaved at one or a few sites (discrete cleavage) in low stress conditions compared to four hundred and forty in apoptotic cells. Many of the cleaved proteins in stressed cells were also found to be cleaved in apoptotic conditions. As expected in apoptotic cells, ~80% of the cleavage events were dependent on caspase 3/caspase 7. Strikingly, upon exposure to non-lethal stresses, no discrete cleavage was detected in cells lacking caspase-3 and caspase-7. This indicates that the proteolytic landscape in stressed viable cells fully depends on the activity of executioner caspases. These results suggest that the so-called executioner caspases fulfill important stress adaptive responses distinct from their role in apoptosis.
Project description:Insulin and insulin-like growth factor signalling regulates a broad spectrum of growth and metabolic responses to a variety of internal and environmental stimuli. Such responses can be tailored so that changes in insulin signalling result in distinct physiological responses to different stimuli. For example, the inhibition of insulin-like signalling is key in the responses of the nematode C. elegans to both osmotic stress and starvation, but these two stresses result in responses that are both physiologically and molecularly distinct. How does reduced insulin-like signalling elicit different responses to different environmental stimuli? We report that neurohormonal signalling involving the C. elegans cytosolic sulfotransferase SSU-1 controls developmental arrest in response to osmotic stress but does not control the distinct developmental arrest that occurs in response to starvation. SSU-1 functions in a single pair of sensory neurons to control intercellular signalling -- likely by catalyzing the synthesis of a steroid hormone -- via the nuclear hormone receptor NHR-1. SSU-1-controlled signalling antagonizes insulin-like signalling and hence modulates insulin sensitivity. In short, we describe a previously unknown neurohormonal signalling pathway that is required specifically for some but not all consequences of reduced insulin-like signalling. In mammals, the nervous system plays a similarly important yet poorly understood role in modulating insulin sensitivity. Our results suggest that the mammalian nervous system might regulate insulin sensitivity via sulfotransferase-controlled neurohormonal signalling.
Project description:Plants are continuously exposed to a myriad of abiotic and biotic stresses. However, the molecular mechanisms by which these stress signals are perceived and transduced are poorly understood. To begin to identify primary stress signal transduction components we have focused on genes that respond rapidly (within 5 min) to stress signals. Because it has been hypothesized that detection of physical stress is a mechanism common to mounting a response against a broad range of environmental stresses, we have utilized mechanical wounding as the stress stimulus and performed whole genome microarray analysis of Arabidopsis thaliana leaf tissue. This led to the identification of a number of rapid wound responsive (RWR) genes. Comparison of RWR genes with published abiotic and biotic stress microarray datasets demonstrates a large overlap across a wide range of environmental stresses. Interestingly, RWR genes also exhibit a striking level and pattern of circadian regulation, with induced and repressed genes displaying antiphasic rhythms. Using bioinformatic analysis, we identified a novel motif overrepresented in the promoters of RWR genes, herein designated as the Rapid Stress Response Element (RSRE). We demonstrate in transgenic plants that multimerized RSREs are sufficient to confer a rapid response to both biotic and abiotic stresses in vivo, thereby establishing the functional involvement of this motif in primary transcriptional stress responses. Collectively, our data provide evidence for a novel cis-element that is distributed across the promoters of an array of diverse stress-responsive genes, poised to respond immediately and coordinately to stress signals. This structure suggests that plants may have a transcriptional network resembling the general stress signaling pathway in yeast and that the RSRE element may provide the key to this coordinate regulation. Experiment Overall Design: Three biological replicates of pooled plants were used for each treatment (Not wounded vs 5 min wounded). Each biological replicate is comprised of 2 technical replicates and a dye swap was performed for each technical replicate.
Project description:Aspergillus display an amazing level of diversity in physiologies, and environments that they occupy. Strategies for coping with diverse environmental stresses have evolved in different Aspergillus species. Therefore, Aspergillus are considered to be good models for investigating the adaptation and response to many natural and anthropogenic environmental stressors. Recent genome sequencing projects in several Aspergillus have provided insights into the molecular and genetic mechanisms underlying their responses to some environmental stressors. However, to better clarify the conserved and differentiated features of the adaptive response to specific stresses and to trace the evolutionary process of environmental adaptation and response in Aspergillus, insight from more Aspergillus species with different evolutionary positions, such as A. glaucus, and thus offer a large number of models of adaptation and response to various environmental stresses. Here, we report a high-quality reference genome assembly of A. glaucus CCHA from the surface of wild vegetation around saltern of Jilin, China, based on sequence data from whole-genome shotgun (WGS) sequencing platforms of Illumina solexa technologies. This assembly contains 106 scaffolds ( >1 Kb; N50 = ~0.795 Mb), has a length of ~28.9 Mb and covers ~97% of the predicted genome size (~120 Mb). Together with the data analyses from comprehensive transcriptomic surveys and comparative genomic analyses, we aim to obtain new insights into molecular mechanisms of the adaptation to living at high salt in the saltern
Project description:A broad diversity of modifications decorate RNA molecules. Originally conceived as static components, evidence is accumulating that some RNA modifications may be dynamic, contributing to cellular responses to external signals and environmental circumstances. A major difficulty in studying these modifications, however, is the need of tailored protocols to map each modification type individually. Here, we present a new approach that uses direct RNA nanopore sequencing to identify diverse RNA modification types present in native RNA molecules. First, we show that each RNA modification type results in a distinct and characteristic base-calling ‘error’ signature, which we validate using a battery of genetic strains lacking either pseudouridine (Ѱ) or 2’-O-methylation (Nm) modifications at known sites. We then demonstrate the value of these signatures for de novo transcriptome-wide prediction of Ѱ modifications, confirming known Ѱ-modified sites in rRNAs, snRNAs and mRNAs, as well as uncovering novel Ѱ sites including a previously unreported Pus4-dependent Ѱ modification in yeast mitochondrial rRNA, which we validate using orthogonal methods. To explore the dynamics of pseudouridylation across environmental stresses, we treat the cells with oxidative, cold and heat stresses, finding that yeast ribosomal rRNA modifications do not change upon environmental exposures. By contrast, our method reveals over a dozen novel heat-sensitive Ѱ-modified sites in snRNAs and snoRNAs, in addition to recovering previously reported sites. Finally, we develop a novel software, nanoRMS, which we show can estimate per-site modification stoichiometries from individual RNA molecules by identifying the reads with altered current intensity profiles, and quantify the RNA modification stoichiometry changes between two conditions. Our work demonstrates that Ѱ RNA modifications can be predicted de novo and in a quantitative manner using native RNA nanopore sequencing.