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RNA sequencing (RNA-Seq) in Saccharomyces cerevisiae

ABSTRACT: Genomic events including gene regulation and chromatin status are controlled by transcription factors. Here we report that the Hsp90 molecular chaperone broadly regulates the transcription factor protein family. Our studies identified a biphasic use of Hsp90 in which early inactivation (15 min) of the chaperone triggered a wide reduction of DNA binding events along the genome with concurrent changes to chromatin structure. Long-term loss (6 h) of Hsp90 resulted in a decline of a divergent yet overlaying pool of transcription factors that produced a distinct chromatin pattern. Although both phases involve protein folding, the early point correlated with Hsp90 acting in a late folding step that is critical for DNA binding function whereas prolonged Hsp90 inactivation led to a significant decrease in the steady-state transcription factor protein levels. Intriguingly, despite the broad chaperone-impact on a variety of transcription factors, the operational influence of Hsp90 was at the level of chromatin with only a mild effect on gene regulation. Thus, Hsp90 selectively governs the transcription factor process overseeing local chromatin structure.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE139266 | GEO | 2019/10/23

REPOSITORIES: GEO

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DNaseI hypersensitivity mapping/DNaseI high-throughput sequencing (DHS-Seq) in Saccharomyces cerevisiae

Project description:We report the application of DHS-Seq and digital genomic footprinting to study chromatin changes and transcription factor-DNA binding upon long-term Hsp90 depletion utilizing the temperature-sensitive allele G170D. By generating about 86 and 85.6 million reads for wild type and mutant, we were able to reconstitute the chromatin accessibility and the transcription factor-DNA binding maps under regular conditions and under conditions where Hsp90 was long-term inactivated. We find that there is a global reduction of transcription factor binding sites with concurrent loss of open chromatin upon Hsp90 inactivation. This data was used in conjunction with our previous work involving DHS-Seq studies and short-term Hsp90 depletion (GEO GSE88875) to distinguish the affected transcription factor networks and the chromatin changes upon short- and long-term Hsp90 depletion. We identified two different modes of Hsp90 operation on transcription factor activities – short-term inactivation of Hsp90 altered transcription factor DNA binding activities, whereas long-term Hsp90 inactivation affected the steady-state levels of transcription factors. Overall, this study shows that Hsp90 regulates multiple transcription factor protein families and modulates chromatin architecture on a genome-wide scale.

2019-10-23 | GSE139268 | GEO

Persistent activation of mRNA translation by transient Hsp90 inhibition

Project description:The heat shock protein 90 (Hsp90) chaperone functions as a protein-folding buffer and plays a unique role promoting the evolution of new heritable traits. To better understand how Hsp90 can affect mRNA translation we screened more than 1600 factors involved in mRNA regulation for physical interactions with Hsp90 in human cells. The mRNA binding protein CPEB2 strongly binds Hsp90 via its prion domain. In a yeast model, transient inhibition of Hsp90 resulted in persistent activation of a CPEB translation reporter even in the absence of exogenous CPEB that persisted for 30 generations after the inhibitor was removed. Ribosomal profiling revealed that some endogenous yeast mRNAs, including HAC1, show a persistent change in translation efficiency following transient Hsp90 inhibition. Thus, transient loss of Hsp90 function can promote a non-genetic inheritance of a translational state affecting specific mRNAs, introducing a new mechanism by which Hsp90 can promote phenotypic variation.

2020-08-11 | GSE153945 | GEO

A systematic analysis of nuclear heat-shock protein 90 identifies a metazoan-specific regulatory module

Project description:Molecular chaperones such as heat-shock proteins (HSPs) help in protein folding and complex assembly processes. Their role in cytosol has been very well elucidated. Chaperones are also present in the nucleus, a compartment where proteins enter after being fully folded in the cytosol, raising an important question about chaperones function in this compartment. We have performed a systematic analysis of nuclear heat- shock protein 90 to identify regulatory functions of this chaperone in the nucleus. Combining physical and genetic interactomes with a cancer co-expression screen allowed us to define 'core functional interactors' of nuclear HSP90 consisting of five proteins. Using transcriptional studies we identified Host Cell Factor C1 (HCFC1) as a metazoan-specific transcriptional regulator that depends on HSP90 for its stability in the nucleus. We found that HSP90 is required for optimal activity of HCFC1 in transcription. Thus our study provides the first global insight into the function of nuclear HSP90.

2019-11-08 | GSE126151 | GEO

Cryo-EM structure of the cytosol AhR complex

Project description:Aryl hydrocarbon receptor (AhR) is an important ligand-activated transcription factor involved in the regulation of various important physiological functions. AhR can be activated by a variety of signals with different affinities, including xenobiotics and endogenous signals. In the absence of ligand, AhR forms a stable multiprotein complex in the cytosol with the chaperone Hsp90 and co-chaperon p23, XAP2.

2022-12-26 | PXD038120 | JPOST Repository

Nucleosome binding by the pioneer transcription factor OCT4

Project description:The nucleosome is a fundamental unit of chromatin in eukaryotes, and generally prevents the binding of transcription factors to genomic DNA. Pioneer transcription factors overcome the nucleosome barrier, and bind their target DNA sequences in chromatin. OCT4 is a representative pioneer transcription factor that plays a role in stem cell pluripotency. In the present study, we biochemically analyzed the nucleosome binding by OCT4. Crosslinking mass spectrometry showed that OCT4 binds the nucleosome.

2020-05-13 | PXD019160 | JPOST Repository

A direct interplay between the co-chaperones Hop and p23 regulates cycle progression and client folding in the Hsp70/Hsp90 chaperone machineries

Project description:Folding of stringent clients requires transfer from Hsp70 to Hsp90. The co-chaperone Hop physically connects the chaperone machineries. Here we define its role from the remodeling of Hsp70/40-client complexes to the mechanism of client transfer and the conformational switching from stalled to active client-processing states of Hsp90. We show that Hsp70 together with Hsp40 completely unfolds a stringent client, the glucocorticoid receptor ligand binding domain (GR-LBD) in large assemblies. Hop remodels these for efficient transfer onto Hsp90. As p23 enters, Hsp70 leaves the complex via switching between binding sites in Hop. To proceed to client folding, current concepts assume that Hop dissociates and the co-chaperone p23 stabilizes the Hsp90 closed state. In contrast, we show that p23 directly interacts with Hop, relieves the stalling Hsp90-Hop interaction and closes Hsp90. This reaction allows folding of the client and is thus the key regulatory step for the progression of the chaperone cycle. To study the interaction between the different proteins, especially p23 and the DP2 domain of Hop, we performed crosslinking-MS.

2022-02-24 | PXD027413 | Pride

Hsp90-downregulation influences the heat-shock response, innate immune response and onset of oocyte development in nematodes.

Project description:Hsp90 is a molecular chaperone involved in the regulation and maturation of kinases and transcription factors. In C. elegans Hsp90 participates in the development of fertility, maintenance of muscle structure and the regulation of stress response and dauer state. To understand the consequences of Hsp90-depletion we studied Hsp90 RNAi-treated nematodes by DNA microarrays and mass spectrometry. We find that upon development of phenotypes the levels of chaperones and cofactors are increased, while specific proteins related to the innate immune response are specifically depleted. We further uncover Hsp90-dependent signatures of gonad development and larval development. Using reporter strains for the responsive genes skr-5, dod-24 and clec-60, we confirm an influence on the innate immune response in intestinal tissues, while alterations to development become evident in strains reporting on the presence of ZIP-8, CAV-1 and SEPA-1 in the gonad arms and very early embryos. These observations add molecular details to the Hsp90-dependent processes during development and stress responses and imply that multiple interactions of this chaperone system are relevant for the nematode’s life and development.

2018-10-17 | PXD006185 | Pride

Hsp90 RNAi in C. elegans

Project description:Hsp90 is a molecular chaperone involved in the regulation and maturation of kinases and transcription factors. In Caenorhabditis elegans, it contributes to the development of fertility, maintenance of muscle structure, the regulation of heat-shock response and dauer state. To understand the consequences of Hsp90-depletion, we studied Hsp90 RNAi-treated nematodes by DNA microarrays and mass spectrometry. We find that upon development of phenotypes the levels of chaperones and Hsp90 cofactors are increased, while specific proteins related to the innate immune response are depleted. In microarrays, we further find many differentially expressed genes related to gonad and larval development. These genes form an expression cluster that is regulated independently from the immune response implying separate pathways of Hsp90-involvement. Using fluorescent reporter strains for the differentially expressed immune response genes skr-5, dod-24 and clec-60 we observe that their activity in intestinal tissues is influenced by Hsp90-depletion. Instead, effects on the development are evident in both gonad arms. After Hsp90-depletion, changes can be observed in early embryos and adults containing fluorescence-tagged versions of SEPA-1, CAV-1 or PUD-1, all of which are downregulated after Hsp90-depletion. Our observations identify molecular events for Hsp90-RNAi induced phenotypes during development and immune responses, which may help to separately investigate independent Hsp90-influenced processes that are relevant during the nematode’s life and development. We used microarrays to detail the global programme of gene expression after RNAi-mediated Hsp90 knock-down.

2017-10-17 | GSE105030 | GEO

Selective ribosome profiling reveals the co-translational chaperone action of trigger factor in vivo

Project description:As nascent polypeptides exit ribosomes, they are engaged by a series of processing, targeting and folding factors. Here we present a selective ribosome profiling strategy that enables global monitoring of when these factors engage polypeptides in the complex cellular environment. Studies of the Escherichia coli chaperone Trigger Factor (TF) reveal that, while TF can interact with many polypeptides, Î²-barrel outer membrane proteins are the most prominent substrates. Loss of TF leads to broad outer membrane defects and premature, cotranslational protein translocation. While in vitro studies suggested that TF is prebound to ribosomes waiting for polypeptides to emerge from the exit channel, we find that in vivo TF engages ribosomes only after ~100 amino acids are translated. Moreover, excess TF interferes with cotranslational removal of the N-terminal formyl methionine. Our studies support a triaging model in which proper protein biogenesis relies on the fine-tuned, sequential engagement of processing, targeting ad folding factors. Examination of translation in the Gram-negative bacterium Escherichia coli, as well as an analysis of the interactions between nascent chains and the molecular chaperone Trigger Factor.

2011-12-09 | E-GEOD-33671 | biostudies-arrayexpress

High-resolution mapping defines the cooperative architecture of Polycomb Response Elements

Project description:Polycomb-mediated chromatin repression modulates gene expression during development in metazoans. Binding of multiple sequence-specific factors at discrete Polycomb Response Elements (PREs) is thought to recruit repressive complexes that spread across an extended chromatin domain. To dissect the structure of PREs, we applied high-resolution mapping of non-histone chromatin proteins in native chromatin of Drosophila cells. Analysis of occupied sites reveal cooperative interactions between transcription factors that stabilize Polycomb anchoring to DNA, and implicate the general transcription factor Adf1 as a novel PRE component. By comparing two Drosophila cell lines with differential chromatin states, we provide evidence that repression is accomplished at multiple steps in transcription, including inactivation of distant enhancers, enhanced Polycomb recruitment to PREs and target promoters, and elevated stalling of RNAPII in repressed genes. These results suggest that the stability of complexes bridging promoters, enhancers, and PREs is a crucial aspect of developmentally regulated gene expression. Native chromatin immunoprecipitation of histones, transcription factors and Polycomb protein in Drosophila cell lines.

2014-02-08 | E-GEOD-47829 | biostudies-arrayexpress

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