Genome-wide binding profile for Heat Shock Factor (HSF).
Ontology highlight
ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE19025 | GEO | 2010/09/02
SECONDARY ACCESSION(S): PRJNA120619
REPOSITORIES: GEO
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Project description:Sequence-specific transcription factors (TFs) are critical for specifying patterns and levels of gene expression, but the DNA elements to which they can bind are not always sufficient to specify their binding in vivo. In eukaryotes, the binding of a TF is in competition with a constellation of other proteins, including histones which package DNA into nucleosomes. Here, we examine using the ChIP-seq assay, the genome-wide distribution of Drosophila Heat Shock Factor (HSF), a TF whose binding activity is mediated by heat shock-induced trimerization. We detect HSF binding to 464 sites, the vast majority of which contain HSF Sequence-binding Elements (HSEs) in Drosophila S2 cells, but these HSF-bound sites represent only a small fraction of HSEs present in the genome. We find a strong correlation of bound HSEs to active chromatin marks present prior to HSF binding, indicating an HSEM-bM-^@M-^Ys residence in open chromatin is a primary determinant of whether HSF can bind following heat shock. A single mock immunoprecipitation (IP) using the pre-innoculated animal serum was used as a background dataset for this study. For each condition (NHS and 20minute HS), we performed two independent HSF-ChIP-seq experiments. In addition, we performed two independent HSF-ChIP-seq experiments for each condition (NHS and 20minute HS) in cells that were highly depleted of HSF by RNAi.
2010-09-02 | E-GEOD-19025 | biostudies-arrayexpress
Project description:DNA sequence and local chromatin landscape act jointly to determine transcription factor (TF) binding intensity profiles. To disentangle these influences, we developed an experimental approach, called protein/DNA binding and high-throughput sequencing (PB-seq), that allows the binding energy landscape to be characterized genome-wide in the absence of chromatin. We applied our methods to the Drosophila Heat Shock Factor (HSF), which inducibly binds a target DNA sequence element (HSE) following heat shock stress. PB-seq involves incubating sheared naked genomic DNA with recombinant HSF, partitioning the HSF-bound and HSF-free DNA, and then detecting HSF-bound DNA by high throughput sequencing. We compared PB-seq binding profiles with ones observed in vivo by ChIP-seq, and developed statistical models to predict the observed departures from idealized binding patterns based on covariates describing the local chromatin environment. We found that DNase I hypersensitivity and tetra-acetylation of H4 were the most influential covariates in predicting changes in HSF binding affinity. We also investigated the extent to which DNA accessibility, as measured by digital DNase I footprinting data, could be predicted from MNase-seq data and the ChIP-chip profiles for many histone modifications and TFs, and found GAGA element associated factor (GAF), tetra-acetylation of H4, and H4K16 acetylation to be the most predictive covariates. Lastly, we generated an unbiased model of HSF binding sequences, which revealed distinct biophysical properties of the HSF/HSE interaction and a previously unrecognized substructure within the HSE. These findings provide new insights into the interplay between the genomic sequence and the chromatin landscape in determining transcription factor binding intensity. We performed an in vitro binding experiment with purified HSF and naked, sheared genomic Drosophila S2 DNA (PB-seq), to derive an accurate set of potential HSF binding sites in the Drosophila genome. HSF-bound DNA was specifically eluted and detected by high throughput sequencing. Drosophila HSF was N-terminally tagged with glutathione s-transferase and a tobacco etch virus (TEV) protease cleavage site. The C-terminus of the recombinant HSF was fused to the 3xFLAG epitope. Recombinant HSF was purified from E. coli with glutathione resin as previously described (PMID: 20078429) , with the following modifications: HSF-3xFLAG elution was achieved by addition of 6xHistidine tagged TEV protease and TEV protease was cleared from the HSF preparation using a Nickel-NTA column. We incubated 600pM HSF and 2500ng genomic DNA (sonicated to 100-600bp fragment size as previously described in PMID: 20844575) in 1500μl final volume of 1xHSF binding buffer and let it come to equilibrium for an hour at room temperature. We added 20μl ANTI-FLAG M2 affinity gel for 10 minutes, washed 8 times with 1xHSF binding buffer to remove unbound DNA; 3xFLAG peptide was added to a final concentration of 200ng/μl to specifically elute HSF and HSF-bound DNA. The mock IP was done in the absence of recombinant HSF.
2012-02-06 | E-GEOD-32570 | biostudies-arrayexpress
Project description:DNA sequence and local chromatin landscape act jointly to determine transcription factor (TF) binding intensity profiles. To disentangle these influences, we developed an experimental approach, called protein/DNA binding and high-throughput sequencing (PB-seq), that allows the binding energy landscape to be characterized genome-wide in the absence of chromatin. We applied our methods to the Drosophila Heat Shock Factor (HSF), which inducibly binds a target DNA sequence element (HSE) following heat shock stress. PB-seq involves incubating sheared naked genomic DNA with recombinant HSF, partitioning the HSF-bound and HSF-free DNA, and then detecting HSF-bound DNA by high throughput sequencing. We compared PB-seq binding profiles with ones observed in vivo by ChIP-seq, and developed statistical models to predict the observed departures from idealized binding patterns based on covariates describing the local chromatin environment. We found that DNase I hypersensitivity and tetra-acetylation of H4 were the most influential covariates in predicting changes in HSF binding affinity. We also investigated the extent to which DNA accessibility, as measured by digital DNase I footprinting data, could be predicted from MNase-seq data and the ChIP-chip profiles for many histone modifications and TFs, and found GAGA element associated factor (GAF), tetra-acetylation of H4, and H4K16 acetylation to be the most predictive covariates. Lastly, we generated an unbiased model of HSF binding sequences, which revealed distinct biophysical properties of the HSF/HSE interaction and a previously unrecognized substructure within the HSE. These findings provide new insights into the interplay between the genomic sequence and the chromatin landscape in determining transcription factor binding intensity.
2012-02-06 | GSE32570 | GEO
Project description:Proctor2005 - Actions of chaperones and their
role in ageing
This model is described in the article:
Modelling the actions of
chaperones and their role in ageing.
Proctor CJ, Soti C, Boys RJ,
Gillespie CS, Shanley DP, Wilkinson DJ, Kirkwood TB.
Mech. Ageing Dev. 2005 Jan; 126(1):
119-131
Abstract:
Many molecular chaperones are also known as heat shock
proteins because they are synthesised in increased amounts
after brief exposure of cells to elevated temperatures. They
have many cellular functions and are involved in the folding of
nascent proteins, the re-folding of denatured proteins, the
prevention of protein aggregation, and assisting the targeting
of proteins for degradation by the proteasome and lysosomes.
They also have a role in apoptosis and are involved in
modulating signals for immune and inflammatory responses.
Stress-induced transcription of heat shock proteins requires
the activation of heat shock factor (HSF). Under normal
conditions, HSF is bound to heat shock proteins resulting in
feedback repression. During stress, cellular proteins undergo
denaturation and sequester heat shock proteins bound to HSF,
which is then able to become transcriptionally active. The
induction of heat shock proteins is impaired with age and there
is also a decline in chaperone function. Aberrant/damaged
proteins accumulate with age and are implicated in several
important age-related conditions (e.g. Alzheimer's disease,
Parkinson's disease, and cataract). Therefore, the balance
between damaged proteins and available free chaperones may be
greatly disturbed during ageing. We have developed a
mathematical model to describe the heat shock system. The aim
of the model is two-fold: to explore the heat shock system and
its implications in ageing; and to demonstrate how to build a
model of a biological system using our simulation system
(biology of ageing e-science integration and simulation
(BASIS)).
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and identified by:
BIOMD0000000091.
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2024-09-02 | BIOMD0000000091 | BioModels
Project description:The goal of this RNA-Seq analysis was to identify genes differentially expressed in wild type (N2) and a hypomorphic mutant of the gene encoding heat shock factor 1 {hsf-1(sy441)} at normal conditions and upon heat shock. This study aimed to identify genes that are up- or downregulated when HSF-1 activity is impaired at 20 ºC. We also aimed to identify gene that are regulated by HSF-1 upon heat stress by comparing differentially expressed genes upon heat shock in wild type and in hsf-1(sy441) mutant background.
2024-06-29 | GSE241011 | GEO
Project description:To understand the function and regulation of the C. elegans heat shock factor (HSF-1) in larval development, we have used ChIP-seq to analyze the occupancy of HSF1 and RNA Pol II in L2 larvae and young adult (YA) animals grown at 20°C or upon heat shock at 34°C for 30 min. In addition, we have used RNA-seq to analyze the transcriptomes of wild type (N2), hsf-1(ok600) mutants and hsf-1(ok600); rmSi1[hsf-1::gfp] L2 larvae grown at 20°C and characterized the gene expression change by heat shock in wild type (N2), hsf-1(sy441) and hsf-1(sy441);rmSi1[hsf-1::gfp] animals at L2 stage.
2016-10-12 | GSE81520 | GEO
Project description:To understand the function and regulation of the C. elegans heat shock factor (HSF-1) in larval development, we have used ChIP-seq to analyze the occupancy of HSF1 and RNA Pol II in L2 larvae and young adult (YA) animals grown at 20°C or upon heat shock at 34°C for 30 min. In addition, we have used RNA-seq to analyze the transcriptomes of wild type (N2), hsf-1(ok600) mutants and hsf-1(ok600); rmSi1[hsf-1::gfp] L2 larvae grown at 20°C and characterized the gene expression change by heat shock in wild type (N2) animals at L2 stage.
2016-10-12 | GSE81521 | GEO
Project description:To understand the function and regulation of the C. elegans heat shock factor (HSF-1) in larval development, we have used ChIP-seq to analyze the occupancy of HSF1 and RNA Pol II in L2 larvae and young adult (YA) animals grown at 20°C or upon heat shock at 34°C for 30 min. In addition, we have used RNA-seq to analyze the transcriptomes of wild type (N2), hsf-1(ok600) mutants and hsf-1(ok600); rmSi1[hsf-1::gfp] L2 larvae grown at 20°C and characterized the gene expression change by heat shock in wild type (N2) animals at L2 stage.
2016-10-12 | GSE81522 | GEO
Project description:Genome-wide binding profile for Heat Shock Factor (HSF).
| PRJNA120619 | ENA
Project description:To mitigate the deleterious effects of temperature increases on cellular organization and proteotoxicity, organisms have developed mechanisms to respond to heat stress. In eukaryotes, HSF1 is the master regulator of the heat shock transcriptional response, but the heat shock response pathway is not yet fully understood. From a forward genetic screen for suppressors of heat shock induced gene expression in Caenorhabditis elegans, we found a new allele of hsf-1 that alters its DNA-binding domain, and we found three additional alleles of sup-45, a previously molecularly uncharacterized genetic locus. We identified sup-45 as one of the two hitherto unknown C. elegans orthologs of the human AF4/FMR2 family proteins, which are involved in regulation of transcriptional elongation rate. We thus renamed sup-45 as affl-2 (AF4/FMR2-Like). Through RNA-seq, we demonstrated that affl-2 mutants are deficient in heat shock induced transcription. Additionally, affl-2 mutants have herniated intestines, while worms lacking its sole paralog (affl-1) appear wild type. AFFL-2 is a broadly expressed nuclear protein, and nuclear localization of AFFL-2 is necessary for its role in heat shock response. affl-2 and its paralog are not essential for proper HSF-1 expression and localization after heat shock, which suggests that affl-2 may function downstream or parallel of hsf-1. Our characterization of affl-2 provides insights into the regulation of heat shock induced gene expression to protect against heat stress.
2020-05-27 | GSE151164 | GEO