Mediator Recruitment to Heat Shock Genes Requires Dual Hsf1 Activation Domains and Mediator Tail Subunits Med15 and Med16

Kim, Sun‐Young; Gross, David S.

doi:10.1074/jbc.m112.449553

Cited by 70 publications

(100 citation statements)

References 75 publications

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“…Previous work demonstrated the rapid, robust recruitment of Mediator to Hsf1-regulated genes in response to heat shock (27,44). Given that the genomic regions with which Mediator associates in its global regulatory role are controversial and may be gene dependent (57-61), we wished to more precisely map where this recruitment takes place.…”

Section: Resultsmentioning

confidence: 99%

“…We initially investigated the role of Med14, given that it serves as a physical and functional scaffold connecting the head, middle, and tail modules (16,(19)(20)(21), as well as previous indications that it governs HSP gene expression through its influence on Hsf1 binding and Pol II recruitment and postrecruitment steps (27,31,38). The Med14 AA strain grew normally on rich medium at 15°C, 30°C, and 37°C, while as expected its growth was strongly inhibited on medium containing rapamycin (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…ChIP experiments were performed as previously described (27), except as noted below. Mid-log-phase cultures (typically 500 ml) were used in both rapamycin and heat shock time course experiments; 50-ml aliquots were removed at each time point, to which formaldehyde was added to a final concentration of 1%.…”

Section: Methodsmentioning

confidence: 99%

“…The tail module harbors subunits that are frequently targeted by activators. For example, the conserved subunit Med15 serves as the target of the yeast activators Gcn4, Gal4, Oaf1, Pdr1/Pdr3, and Hsf1 (10,(23)(24)(25)(26)(27), as well as mammalian sterol regulatory elementbinding protein (SREBP) (11). Med14, generally assigned to either the tail or middle, has recently been shown to serve as a central scaffold necessary for integrating the three separate modules of the core into a single functional entity (16,(19)(20)(21).…”

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confidence: 99%

“…Following exposure to thermal stress (or other proteotoxic stimuli), inactive Hsf1 monomers trimerize and cooperatively bind to the remaining, loweraffinity heat shock elements (HSEs) in chromatin (43). DNAbound Hsf1 then triggers the recruitment of Mediator and other coactivators (27,(44)(45)(46)(47)(48), culminating in the assembly of the Pol II initiation complex at HSP core promoters and transcription.…”

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confidence: 99%

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Evidence for Multiple Mediator Complexes in Yeast Independently Recruited by Activated Heat Shock Factor

Anandhakumar

Moustafa

Chowdhary

et al. 2016

Molecular and Cellular Biology

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Mediator is an evolutionarily conserved coactivator complex essential for RNA polymerase II transcription. Although it has been generally assumed that in Saccharomyces cerevisiae, Mediator is a stable trimodular complex, its structural state in vivo remains unclear. Using the "anchor away" (AA) technique to conditionally deplete select subunits within Mediator and its reversibly associated Cdk8 kinase module (CKM), we provide evidence that Mediator's tail module is highly dynamic and that a subcomplex consisting of Med2, Med3, and Med15 can be independently recruited to the regulatory regions of heat shock factor 1 (Hsf1)-activated genes. Fluorescence microscopy of a scaffold subunit (Med14)-anchored strain confirmed parallel cytoplasmic sequestration of core subunits located outside the tail triad. In addition, and contrary to current models, we provide evidence that Hsf1 can recruit the CKM independently of core Mediator and that core Mediator has a role in regulating postinitiation events. Collectively, our results suggest that yeast Mediator is not monolithic but potentially has a dynamic complexity heretofore unappreciated. Multiple species, including CKM-Mediator, the 21-subunit core complex, the Med2-Med3-Med15 tail triad, and the foursubunit CKM, can be independently recruited by activated Hsf1 to its target genes in AA strains.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Evidence for Multiple Mediator Complexes in Yeast Independently Recruited by Activated Heat Shock Factor

Anandhakumar

Moustafa

Chowdhary

et al. 2016

Molecular and Cellular Biology

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MED12 interacts with the heat‐shock transcription factor HSF1 and recruits CDK8 to promote the heat‐shock response in mammalian cells

et al. 2021

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Activated and promoter-bound heat-shock transcription factor 1 (HSF1) induces RNA polymerase II recruitment upon heat shock, and this is facilitated by the core Mediator in Drosophila and yeast. Another Mediator module, CDK8 kinase module (CKM), consisting of four subunits including MED12 and CDK8, plays a negative or positive role in the regulation of transcription; however, its involvement in HSF1-mediated transcription remains unclear. We herein demonstrated that HSF1 interacted with MED12 and recruited MED12 and CDK8 to the HSP70 promoter during heat shock in mammalian cells. The kinase activity of CDK8 (and its paralog CDK19) promoted HSP70 expression partly by phosphorylating HSF1-S326 and maintained proteostasis capacity. These results indicate an important role for CKM in the protection of cells against proteotoxic stress.

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The Mediator subunit MED12 promotes formation of HSF1 condensates on heat shock response element arrays in heat‐shocked cells

et al. 2023

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Upon heat shock, activated heat shock transcription factor 1 (HSF1) binds to the heat shock response elements (HSEs) in the promoters of mammalian heat shock protein (HSP)-encoding genes and recruits the preinitiation complex and coactivators, including Mediator. These transcriptional regulators may be concentrated in phase-separated condensates around the promoters, but they are too minute to be characterized in detail. We herein established HSF1 À/À mouse embryonic fibroblasts harbouring HSP72-derived multiple HSE arrays and visualized the condensates of fluorescent protein-tagged HSF1 with liquid-like properties upon heat shock. Using this experimental system, we demonstrate that endogenous MED12, a subunit of Mediator, is concentrated in artificial HSF1 condensates upon heat shock. Furthermore, the knockdown of MED12 markedly reduces the size of condensates, suggesting an important role for MED12 in HSF1 condensate formation.

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Mediator Recruitment to Heat Shock Genes Requires Dual Hsf1 Activation Domains and Mediator Tail Subunits Med15 and Med16

Cited by 70 publications

References 75 publications

Evidence for Multiple Mediator Complexes in Yeast Independently Recruited by Activated Heat Shock Factor

Evidence for Multiple Mediator Complexes in Yeast Independently Recruited by Activated Heat Shock Factor

MED12 interacts with the heat‐shock transcription factor HSF1 and recruits CDK8 to promote the heat‐shock response in mammalian cells

The Mediator subunit MED12 promotes formation of HSF1 condensates on heat shock response element arrays in heat‐shocked cells

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