The extent to which carbon flux is directed towards fermentation vs. respiration differs between cell types and environmental conditions. Understanding the basic cellular processes governing carbon flux is challenged by the complexity of the metabolic and regulatory networks. To reveal the genetic basis for natural diversity in channeling carbon flux, we applied Quantitative Trait Loci analysis by phenotyping and genotyping hundreds of individual F2 segregants of budding yeast that differ in their capacity to ferment the pentose sugar xylulose. Causal alleles were mapped to the RXT3 and PHO23 genes, two components of the large Rpd3 histone deacetylation complex. We show that these allelic variants modulate the expression of SNF1/AMPK-dependent respiratory genes. Our results suggest that over close evolutionary distances, diversification of carbon flow is driven by changes in global regulators, rather than adaptation of specific metabolic nodes. Such regulators may improve the ability to direct metabolic fluxes for biotechnological applications. Overall design: mRNA profiles of S. cerevisiae strain BY4741 with either the RXT3 or PHO23 genes either deleted, replaced by S. cerevisiae T73 allele or replaced by S. cerevisiae PHO23 allele
Natural Diversity in Pentose Fermentation Is Explained by Variations in Histone Deacetylases.
Cell line, Subject
View SamplesCells constantly adapt to changes in their environment. In the majority of cases, the environment shifts between conditions that were previously encountered during the course of evolution, thus enabling evolutionary-programmed responses. In rare cases, however, cells may encounter a new environment to which a novel response is required. To characterize the first steps in adaptation to a novel condition, we studied budding yeast growth on xylulose, a sugar that is very rarely found in the wild. We previously reported that growth on xylulose induces the expression of amino-acid biosynthesis genes, in multiple natural yeast isolates. This induction occurs despite the presence of amino acids in the growth medium and is a unique response to xylulose, not triggered by any of the naturally available carbon sources tested. Propagating these strains for ~300 generations on xylulose significantly improved their growth rate. Notably, the most significant change in gene expression was the loss of amino acid biosynthesis gene induction. Furthermore, the reduction in amino-acid biosynthesis gene expression on xylulose was strongly correlated with the improvement in growth rate, suggesting that internal depletion of amino-acids presented the major bottleneck limiting growth in xylulose. We discuss the possible implications of our results for explaining how cells maintain the balance between supply and demand of amino acids during growth in evolutionary 'familiar' vs. 'novel' conditions. Overall design: mRNA profiles of 12 wt S. cerevisiae strains grown on either YPD or YP-xylulose, before and after 300 generations evolution on YP-xylulose
Rapid evolutionary adaptation to growth on an 'unfamiliar' carbon source.
Cell line, Subject
View SamplesOBJECTIVE: Acromegaly is a rare endocrine disorder with excess growth hormone (GH) production. This disorder has important metabolic effects in insulin resistance and lipolysis. The objective of this study was to explore transcriptional changes induced by GH in adipose tissue. METHODS: The patients underwent clinical and metabolic profiling including assessment of HOMA-IR. Explants of adipose tissue were assayed ex-vivo for lipolysis and ceramide levels. Adipose tissue was analyzed by RNA sequencing (RNA-seq). RESULTS: There was evidence of reduced insulin sensitivity based on the increase in fasting glucose, insulin and HOMA-IR score. We observed several previously reported transcriptional changes (IGF1, IGFBP3) as well as several novel transcriptional changes, some of which may be important for GH signal regulation (PTPN3 and PTPN4) and the effect of GH on growth and proliferation. Several transcripts could potentially be important in GH-induced metabolic changes. Specifically, induction of LPL, ABHD5, and ACVR1C could contribute to enhanced lipolysis and may explain the suggestive enhancement of adipose tissue lipolysis in acromegaly patients as reflected by glycerol release from the explants of the two groups of patients (p=0.09). Higher expression of SCD and TCF7L2 could contribute to insulin resistance. Expression of HSD11B1 was reduced and GR was increased, predicting modified glucocorticoid activity in acromegaly. CONCLUSIONS: We identified the acromegaly gene expression signature in human adipose tissue. The significance of altered expression of specific transcripts will enhance our understanding of the metabolic and proliferative changes associated with acromegaly. Overall design: DESIGN: Patients with acromegaly (n=9) or non-functioning pituitary adenoma (n=11) were prospectively observed from March 2011 to June 2012. Sequencing was performed on RNA from 7 acromegaly patients and 11 controls.
Gene Expression Signature in Adipose Tissue of Acromegaly Patients.
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View SamplesThis research identifies a novel protein required for paramutation at the maize purple plant1 locus. This 'required to maintain repression2' (RMR2) protein represents the founding member of a plant-specific clade of hypothetical proteins. We show that RMR2 is required for transcriptional repression at the Pl1-Rhoades haplotype, for accumulation of 24 nt RNA species, and for maintenance of a 5-methylcytosine pattern distinct from that maintained by RNA polymerase IV. Genetic tests indicate that RMR2 is not required for paramutation occurring at the red1 locus. These results distinguish the paramutation-type mechanisms operating at specific haplotypes. The RMR2 clade of proteins provides a new entry point for understanding the diversity of epigenomic control operating in higher plants. Overall design: Examination of small RNAs using Illumina's sequencing-by-synthesis (SBS) platform to deep sequence small RNA libraries made from the 4-cm cobs of rmr2 mutant and non-mutant siblings.
required to maintain repression2 is a novel protein that facilitates locus-specific paramutation in maize.
Specimen part, Subject
View SamplesOT-I T cells were exposed to CpG ODN-activated CCR5ko Lymph nodes for 6 h, stained for surface CCR5 and FACS-sorted into CCR5+ and CCR5- fractions
Transient Surface CCR5 Expression by Naive CD8+ T Cells within Inflamed Lymph Nodes Is Dependent on High Endothelial Venule Interaction and Augments Th Cell-Dependent Memory Response.
Specimen part
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. Wild type cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. ?phm3 cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. pho90_OX cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. phm3 damp cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
View SamplesDepletion of essential nutrients triggers regulatory programs that prolong cell growth and survival. Starvation-induced processes increase nutrient transport, mobilize nutrient storage, and recycle nutrients between cellular components. This leads to an effective increase in intracellular nutrients, which may act as a negative feedback that down-regulates the starvation program. To examine how cells overcome this potential instability, we followed the transcription response of budding yeast transferred to medium lacking phosphate. Genes were induced in two temporal waves. The first wave was stably maintained and persisted even upon phosphate replenishment, indicating a positive feedback loop. This commitment was abolished after two hours with the induction of the second expression wave, coinciding with the reduction in cell growth rate. We identify genes that mediate this loss of commitment, and show that the overall temporal stability of the expression response depends on the sequential pattern of gene induction. Our results emphasize the key role of gene expression dynamics in optimizing cellular adaptation. ?vip1 cells were grown at high Phosphate medium, washed and transferred to no phosphate medium. Sample were taken every 15 minuets for 6 hours Overall design: 25 samples were taken during the time course. Expression data was normalized to the first time point (cells grown at high phosphate medium)
Sequential feedback induction stabilizes the phosphate starvation response in budding yeast.
Subject
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