Unknown,Transcriptomics,Genomics,Proteomics

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Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress.

ABSTRACT: Understanding the response processes in cellular systems to external perturbations is a central goal of large-scale molecular profiling experiments. We investigated the molecular response of yeast to increased and lowered temperatures relative to optimal reference conditions across two levels of molecular organization: the transcriptome using a whole yeast genome microarray and the metabolome applying the GC/MS technology with in-vivo stable-isotope labeling for accurate relative quantification of a total of 50 different metabolites. The molecular adaptation of yeast to increased or lowered temperatures relative control conditions at both the metabolic and transcriptional level is dominated by temperature-inverted differential regulation patterns of transcriptional and metabolite responses and the temporal response observed to be biphasic. The set of previously described general environmental stress response (ESR) genes showed particularly strong temperature-inverted response patterns. Among the metabolites measured, trehalose was detected to respond strongest to the temperature stress and with temperature-inverted up and downregulation relative to control, mid-temperature conditions. Although associated with the same principal environmental parameter, the two different temperature regimes caused very distinct molecular response patterns at both the metabolite and the transcript level. While pairwise correlations between different transcripts and between different metabolites were found generally preserved under the various conditions, substantial differences were also observed indicative of changed underlying network architectures or modified regulatory relationships. Gene and associated gene functions were identified that are differentially regulated specifically under the gradual stress induction applied here compared to abrupt stress exposure investigated in previous studies, including genes of as of yet unidentified function and genes involved in protein synthesis and energy metabolism. Reference: Strassburg K, Walther D, Takahashi H, Kanaya S, and Kopka J. Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress. OMICS JIB, 2010, 14(3), in press. Time-series with 8 time points for three different ambient temperatures. Single replicate per time point and temperature series.

ORGANISM(S): Saccharomyces cerevisiae

SUBMITTER: Dirk Walther

PROVIDER: E-GEOD-15352 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Understanding the response processes in cellular systems to external perturbations is a central goal of large-scale molecular profiling experiments. We investigated the molecular response of yeast to increased and lowered temperatures relative to optimal reference conditions across two levels of molecular organization: the transcriptome using a whole yeast genome microarray and the metabolome applying the GC/MS technology with in-vivo stable-isotope labeling for accurate relative quantification of a total of 50 different metabolites. The molecular adaptation of yeast to increased or lowered temperatures relative control conditions at both the metabolic and transcriptional level is dominated by temperature-inverted differential regulation patterns of transcriptional and metabolite responses and the temporal response observed to be biphasic. The set of previously described general environmental stress response (ESR) genes showed particularly strong temperature-inverted response patterns. Among the metabolites measured, trehalose was detected to respond strongest to the temperature stress and with temperature-inverted up and downregulation relative to control, mid-temperature conditions. Although associated with the same principal environmental parameter, the two different temperature regimes caused very distinct molecular response patterns at both the metabolite and the transcript level. While pairwise correlations between different transcripts and between different metabolites were found generally preserved under the various conditions, substantial differences were also observed indicative of changed underlying network architectures or modified regulatory relationships. Gene and associated gene functions were identified that are differentially regulated specifically under the gradual stress induction applied here compared to abrupt stress exposure investigated in previous studies, including genes of as of yet unidentified function and genes involved in protein synthesis and energy metabolism. Reference: Strassburg K, Walther D, Takahashi H, Kanaya S, and Kopka J. Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress. OMICS JIB, 2010, 14(3), in press.

Project description:Cellular responses to maladaptive environmental changes—stresses—allow for organismal adaptation to diverse and dynamic conditions. Across the tree of life, cells upregulate a highly conserved transcriptional program in response to so-called proteotoxic stresses such as heat shock. Correspondingly, in eukaryotes, these stresses induce the formation of biomolecular condensates, clusters of mRNA and protein which are referred to as stress granules under severe stress. However, major questions remain about this stress-induced response. How conserved is the condensation response relative to the transcriptional response? How does it vary across environmental niches, and to what extent does it correspond with the conserved transcriptional response? To answer these fundamental questions, we studied the growth, transcriptional, and condensation heat-induced stress responses in three fungal species adapted to thrive in different thermal environments: cryophilic S. kudriavzevii, mesophilic S. cerevisiae, and thermotolerant K. marxianus. Here we show that transcriptional heat shock responses track each species’ evolved temperature range of growth. Further, orthologous proteins—including poly(A)-binding protein, Pab1, a core marker of stress granules—form condensates in vivo at temperatures systematically tuned to the temperature at which the organisms activate the transcriptional heat shock response and slow their growth. In vitro, purified Pab1 from each species condenses autonomously at niche-specific temperatures. Homologous mutations in Pab1 cause similar shifts in relative condensation temperature across species, and crucially, mutations which suppress condensation in vitro also reduce fitness during heat stress. Our findings indicate that stress-induced protein condensation is adaptive, conserved, integrated with the growth and transcriptional responses, and tuned to features of the cellular and organismal environment to initiate at niche-specific levels.

Project description:Adult male fish were exposed to the various temperature acclimation conditions as outlined in the published manuscript and RNA was extracted from fish at each time point as listed in the experiment set description. Abstract: Eurythermal ectotherms commonly thrive in environments that expose them to large variations in temperature on daily and seasonal bases. The roles played by alterations in gene expression in enabling eurytherms to adjust to these two temporally distinct patterns of thermal stress are poorly understood. We used cDNA microarray analysis to examine changes in gene expression in a eurythermal fish, Austrofundulus limnaeus, subjected to long-term acclimation to constant temperatures of 20, 26 and 37 degrees C and to environmentally realistic daily fluctuations in temperature between 20 degrees C and 37 degrees C. Our data reveal major differences between the transcriptional responses in the liver made during acclimation to constant temperatures and in response to daily temperature fluctuations. Control of cell growth and proliferation appears to be an important part of the response to change in temperature, based on large-scale changes in mRNA transcript levels for several key regulators of these pathways. However, cell growth and proliferation appear to be regulated by different genes in constant versus fluctuating temperature regimes. The gene expression response of molecular chaperones is also different between constant and fluctuating temperatures. Small heat shock proteins appear to play an important role in response to fluctuating temperatures whereas larger molecular mass chaperones such as Hsp70 and Hsp90 respond more strongly to chronic high temperatures. A number of transcripts that encode for enzymes involved in the biosynthesis of nitrogen-containing organic osmolytes have gene expression patterns that indicate a possible role for these 'chemical chaperones' during acclimation to chronic high temperatures and daily temperature cycling. Genes important for the maintenance of membrane integrity are highly responsive to temperature change. Changes in fatty acid saturation may be important in long-term acclimation and in response to fluctuating temperatures; however cholesterol metabolism may be most critical for short-term acclimation to fluctuating temperatures. The variable effect of temperature on the expression of genes with daily rhythms of expression indicates that there is a complex interaction between the temperature cycle and daily rhythmicity in gene expression. A number of new hypotheses concerning temperature acclimation in fish have been generated as a result of this study. The most notable of these hypotheses is the possibility that the high mobility group b1 (HMGB1) protein, which plays key roles in the assembly of transcription initiation and enhanceosome complexes, may act as a compensatory modulator of transcription in response to temperature, and thus as a global gene expression temperature sensor. This study illustrates the utility of cDNA microarray approaches in both hypothesis-driven and 'discovery-based' investigations of environmental effects on organisms. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Keywords: all_pairs

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Dynamic transcriptional and metabolic responses in yeast adapting to temperature stress.

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