| 1. |
- Bergenholm, David, 1987, et al.
(författare)
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Reconstruction of a Global Transcriptional Regulatory Network for Control of Lipid Metabolism in Yeast by Using Chromatin Immunoprecipitation with Lambda Exonuclease Digestion
- 2018
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Ingår i: mSystems. - 2379-5077. ; 3:4
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Tidskriftsartikel (refereegranskat)abstract
- To build transcription regulatory networks, transcription factor binding must be analyzed in cells grown under different conditions because their responses and targets differ depending on environmental conditions. We performed wholegenome analysis of the DNA binding of five Saccharomyces cerevisiae transcription factors involved in lipid metabolism, Ino2, Ino4, Hap1, Oaf1, and Pip2, in response to four different environmental conditions in chemostat cultures, which allowed us to keep the specific growth rate constant. Chromatin immunoprecipitation with lambda exonuclease digestion (ChIP-exo) enabled the detection of binding events at a high resolution. We discovered a large number of unidentified targets and thus expanded functions for each transcription factor (e.g., glutamate biosynthesis as a target of Oaf1 and Pip2). Moreover, condition-dependent binding of transcription factors in response to cell metabolic state (e.g., differential binding of Ino2 between fermentative and respiratory metabolic conditions) was clearly suggested. Combining the new binding data with previously published data from transcription factor deletion studies revealed the high complexity of the transcriptional regulatory network for lipid metabolism in yeast, which involves the combinatorial and complementary regulation by multiple transcription factors. We anticipate that our work will provide insights into transcription factor binding dynamics that will prove useful for the understanding of transcription regulatory networks.
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| 2. |
- Börlin, Christoph Sebastian, 1989, et al.
(författare)
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A bioinformatic pipeline to analyze ChIP-exo datasets
- 2019
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Ingår i: Biology Methods and Protocols. - : Oxford University Press (OUP). - 2396-8923. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- The decrease of sequencing cost in the recent years has made genome-wide studies of transcription factor (TF) binding through chromatin immunoprecipitation methods like ChIP-seq and chromatin immunoprecipitation with lambda exonuclease (ChIP-exo) more accessible to a broader group of users. Especially with ChIP-exo, it is now possible to map TF binding sites in more detail and with less noise than previously possible. These improvements came at the cost of making the analysis of the data more challenging, which is further complicated by the fact that to this date no complete pipeline is publicly available. Here we present a workflow developed specifically for ChIP-exo data and demonstrate its capabilities for data analysis. The pipeline, which is completely publicly available on GitHub, includes all necessary analytical steps to obtain a high confidence list of TF targets starting from raw sequencing reads. During the pipeline development, we emphasized the inclusion of different quality control measurements and we show how to use these so users can have confidence in their obtained results.
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| 3. |
- Börlin, Christoph Sebastian, 1989, et al.
(författare)
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Saccharomyces cerevisiae displays a stable transcription start site landscape in multiple conditions
- 2019
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1356 .- 1567-1364. ; 19:2
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Tidskriftsartikel (refereegranskat)abstract
- One of the fundamental processes that determine cellular fate is regulation of gene transcription. Understanding these regulatory processes is therefore essential for understanding cellular responses to changes in environmental conditions. At the core promoter, the regulatory region containing the transcription start site (TSS), all inputs regulating transcription are integrated. Here, we used Cap Analysis of Gene Expression (CAGE) to analyze the pattern of TSSs at four different environmental conditions (limited in ethanol, limited in nitrogen, limited in glucose and limited in glucose under anaerobic conditions) using the Saccharomyces cerevisiae strain CEN.PK113-7D. With this experimental setup, we were able to show that the TSS landscape in yeast is stable at different metabolic states of the cell. We also show that the spatial distribution of transcription initiation events, described by the shape index, has a surprisingly strong negative correlation with measured gene expression levels, meaning that genes with higher expression levels tend to have a broader distribution of TSSs. Our analysis supplies a set of high-quality TSS annotations useful for metabolic engineering and synthetic biology approaches in the industrially relevant laboratory strain CEN.PK113-7D, and provides novel insights into yeast TSS dynamics and gene regulation.
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| 4. |
- Holland, Petter, 1985, et al.
(författare)
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Coupling cell division to metabolic pathways through transcription
- 2018
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Ingår i: Encyclopedia of Bioinformatics and Computational Biology: ABC of Bioinformatics. ; , s. 74-93
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Cellular growth is ensured by alternation of DNA duplication and cell division cycles. This alternation is coordinated by the interplay between enzymatic activities, called kinases, and transcription factors, to keep the cell cycle timing. Here we investigate whether transcription factors may serve as hubs connecting multi-scale cellular networks. A variant of chromatin immunoprecipitation, called ChIP-exo, was performed to identify targets of Forkhead (Fkh) transcription factors across the budding yeast genome. Data analyses indicate that the Fkh-mediated transcriptional program may activate metabolic pathways and synchronize kinase activities to guarantee alternation of DNA duplication and cell division, thereby a timely cell’s cycling.
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| 5. |
- Holland, Petter, et al.
(författare)
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HS1BP3 negatively regulates autophagy by modulation of phosphatidic acid levels
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- A fundamental question is how autophagosome formation is regulated. Here we show that the PX domain protein HS1BP3 is a negative regulator of autophagosome formation. HS1BP3 depletion increased the formation of LC3-positive autophagosomes and degradation of cargo both in human cell culture and in zebrafish. HS1BP3 is localized to ATG16L1-and ATG9-positive autophagosome precursors and we show that HS1BP3 binds phosphatidic acid (PA) through its PX domain. Furthermore, we find the total PA content of cells to be significantly upregulated in the absence of HS1BP3, as a result of increased activity of the PA-producing enzyme phospholipase D (PLD) and increased localization of PLD1 to ATG16L1-positive membranes. We propose that HS1BP3 regulates autophagy by modulating the PA content of the ATG16L1-positive autophagosome precursor membranes through PLD1 activity and localization. Our findings provide key insights into how autophagosome formation is regulated by a novel negative-feedback mechanism on membrane lipids.
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| 6. |
- Holland, Petter, 1985, et al.
(författare)
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Predictive models of eukaryotic transcriptional regulation reveals changes in transcription factor roles and promoter usage between metabolic conditions
- 2019
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 47:10, s. 4986-5000
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Tidskriftsartikel (refereegranskat)abstract
- Transcription factors (TF) are central to transcriptional regulation, but they are often studied in relative isolation and without close control of the metabolic state of the cell. Here, we describe genome-wide binding (by ChIP-exo) of 15 yeast TFs in four chemostat conditions that cover a range of metabolic states. We integrate this data with transcriptomics and six additional recently mapped TFs to identify predictive models describing how TFs control gene expression in different metabolic conditions. Contributions by TFs to gene regulation are predicted to be mostly activating, additive and well approximated by assuming linear effects from TF binding signal. Notably, using TF binding peaks from peak finding algorithms gave distinctly worse predictions than simply summing the low-noise and high-resolution TF ChIP-exo reads on promoters. Finally, we discover indications of a novel functional role for three TFs; Gcn4, Ert1 and Sut1 during nitrogen limited aerobic fermentation. In only this condition, the three TFs have correlated binding to a large number of genes (enriched for glycolytic and translation processes) and a negative correlation to target gene transcript levels.
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| 7. |
- Merid, Simon Kebede, et al.
(författare)
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Epigenome-wide meta-analysis of blood DNA methylation in newborns and children identifies numerous loci related to gestational age
- 2020
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Ingår i: Genome Medicine. - Stockholm : Karolinska Institutet, Dept of Clinical Science and Education, Södersjukhuset. - 1756-994X.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Preterm birth and shorter duration of pregnancy are associated with increased morbidity in neonatal and later life. As the epigenome is known to have an important role during fetal development, we investigated associations between gestational age and blood DNA methylation in children. Methods: We performed meta-analysis of Illumina's HumanMethylation450-array associations between gestational age and cord blood DNA methylation in 3648 newborns from 17 cohorts without common pregnancy complications, induced delivery or caesarean section. We also explored associations of gestational age with DNA methylation measured at 4-18 years in additional pediatric cohorts. Follow-up analyses of DNA methylation and gene expression correlations were performed in cord blood. DNA methylation profiles were also explored in tissues relevant for gestational age health effects: fetal brain and lung. Results: We identified 8899 CpGs in cord blood that were associated with gestational age (range 27-42 weeks), at Bonferroni significance, P < 1.06 × 10- 7, of which 3343 were novel. These were annotated to 4966 genes. After restricting findings to at least three significant adjacent CpGs, we identified 1276 CpGs annotated to 325 genes. Results were generally consistent when analyses were restricted to term births. Cord blood findings tended not to persist into childhood and adolescence. Pathway analyses identified enrichment for biological processes critical to embryonic development. Follow-up of identified genes showed correlations between gestational age and DNA methylation levels in fetal brain and lung tissue, as well as correlation with expression levels. Conclusions: We identified numerous CpGs differentially methylated in relation to gestational age at birth that appear to reflect fetal developmental processes across tissues. These findings may contribute to understanding mechanisms linking gestational age to health effects.
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| 8. |
- Mondeel, Thierry D.G.A., et al.
(författare)
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ChIP-exo analysis highlights Fkh1 and Fkh2 transcription factors as hubs that integrate multi-scale networks in budding yeast
- 2019
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 47:15, s. 7825-7841
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Tidskriftsartikel (refereegranskat)abstract
- The understanding of the multi-scale nature of molecular networks represents a major challenge. For example, regulation of a timely cell cycle must be coordinated with growth, during which changes in metabolism occur, and integrate information from the extracellular environment, e.g. signal transduction. Forkhead transcription factors are evolutionarily conserved among eukaryotes, and coordinate a timely cell cycle progression in budding yeast. Specifically, Fkh1 and Fkh2 are expressed during a lengthy window of the cell cycle, thus are potentially able to function as hubs in the multi-scale cellular environment that interlocks various biochemical networks. Here we report on a novel ChIP-exo dataset for Fkh1 and Fkh2 in both logarithmic and stationary phases, which is analyzed by novel and existing software tools. Our analysis confirms known Forkhead targets from available ChIP-chip studies and highlights novel ones involved in the cell cycle, metabolism and signal transduction. Target genes are analyzed with respect to their function, temporal expression during the cell cycle, correlation with Fkh1 and Fkh2 as well as signaling and metabolic pathways they occur in. Furthermore, differences in targets between Fkh1 and Fkh2 are presented. Our work highlights Forkhead transcription factors as hubs that integrate multi-scale networks to achieve proper timing of cell division in budding yeast.
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| 9. |
- Ouyang, Liming, 1974, et al.
(författare)
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Integrated analysis of the yeast NADPH-regulator Stb5 reveals distinct differences in NADPH requirements and regulation in different states of yeast metabolism
- 2018
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1356 .- 1567-1364. ; 18:8
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Tidskriftsartikel (refereegranskat)abstract
- The Saccharomyces cerevisiae transcription factor (TF) Stb5 is known to be involved in regulating NADPH generation. We explored its role by combining DNA binding studies with transcriptome analysis at four environmental conditions that were selected to cover a range of different metabolic states. Using ChIP-exo, DNA binding targets of Stb5 were found to confirm many previously proposed binding targets, in particular genes encoding enzymes involved in NADPH generation and the pentose-phosphate (PP) pathway. Transcriptome analysis of an STB5 deletion strain revealed transcriptional changes in direct regulation targets of Stb5, including several PP pathway genes as well as additional novel regulatory targets, but interestingly not including the proposed PP pathway flux controlling enzyme Zwf1. Consistently, NADPH levels were found to decrease significantly with STB5 deletion in cultures with aerobic, glucose metabolism. We also found reduced growth for the STB5 deletion strain in similar conditions as those with reduced NADPH levels, supporting a role for Stb5 in NADPH generation through the PP pathway. We finally explored the flux distribution by genome scale modelling simulations and found a decreased flux in both NADPH generating as well as consuming reactions in the STB5 deletion strain.
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