Mutational analysis of human heat-shock transcription factor 1 reveals a regulatory role for oligomerization in DNA-binding specificity

Takemori, Yukiko; Enoki, Yasuaki; Yamamoto, Norio; Fukai, Yo; Adachi, Kaori; Sakurai, Hiroshi

doi:10.1042/bj20090922

Cited by 16 publications

(30 citation statements)

References 53 publications

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“…Human HSF2, but not hHSF1, functionally complements a yeast hsf1Δ null strain, demonstrating that the hHSF2 isoform, which regulates developmentally controlled genes, retains its ancestral ability to control HSP genes (Liu et al 1997). hHSF1 can be made functionally competent in yeast through disruption of a coiled-coil intramolecular interaction domain or substitutions within the DBD, suggesting that human cells normally modulate these interactions to allow stress-induced activation Takemori et al 2009). Analysis of hHSF1 in the yeast system has also revealed that a loop region within the highly conserved DNA binding domain influences promoter recognition and trimerization (Ahn et al 2001).…”

Section: Global Analysis Of the Hsrmentioning

confidence: 99%

The Response to Heat Shock and Oxidative Stress inSaccharomyces cerevisiae

2012

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A common need for microbial cells is the ability to respond to potentially toxic environmental insults. Here we review the progress in understanding the response of the yeast Saccharomyces cerevisiae to two important environmental stresses: heat shock and oxidative stress. Both of these stresses are fundamental challenges that microbes of all types will experience. The study of these environmental stress responses in S. cerevisiae has illuminated many of the features now viewed as central to our understanding of eukaryotic cell biology. Transcriptional activation plays an important role in driving the multifaceted reaction to elevated temperature and levels of reactive oxygen species. Advances provided by the development of whole genome analyses have led to an appreciation of the global reorganization of gene expression and its integration between different stress regimens. While the precise nature of the signal eliciting the heat shock response remains elusive, recent progress in the understanding of induction of the oxidative stress response is summarized here. Although these stress conditions represent ancient challenges to S. cerevisiae and other microbes, much remains to be learned about the mechanisms dedicated to dealing with these environmental parameters.

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Section: Global Analysis Of the Hsrmentioning

confidence: 99%

The Response to Heat Shock and Oxidative Stress inSaccharomyces cerevisiae

2012

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“…1A). The RD harbors ϳ70% of the known HSF1 phosphorylation sites (33) and is capable of repressing HSF1 TAD in the absence of stress, rendering HSF1 inactive under normal conditions (22,27,28), and we therefore mutated the phosphorylation sites within this domain.…”

Section: Hsf1⌬ϳprd and Hsf1mentioning

confidence: 99%

“…A centrally located part of HSF1 is called the regulatory domain (RD). Deletion of the RD results in constitutive DNA-binding activity of HSF1 and induces expression of Hsps in the absence of stress (26)(27)(28). It has also been shown that the RD is self-sufficient in its heat-sensing capacity, since a chimeric transcription factor containing Gal4 DBD -HSF1 RD -VP16 TAD is repressed under normal conditions but is capable of activating transcription in response to stress (22).…”

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confidence: 99%

Uncoupling Stress-Inducible Phosphorylation of Heat Shock Factor 1 from Its Activation

Budzyński

Puustinen

Joutsen

et al. 2015

Molecular and Cellular Biology

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bIn mammals the stress-inducible expression of genes encoding heat shock proteins is under the control of the heat shock transcription factor 1 (HSF1). Activation of HSF1 is a multistep process, involving trimerization, acquisition of DNA-binding and transcriptional activities, which coincide with several posttranslational modifications. Stress-inducible phosphorylation of HSF1, or hyperphosphorylation, which occurs mainly within the regulatory domain (RD), has been proposed as a requirement for HSF-driven transcription and is widely used for assessing HSF1 activation. Nonetheless, the contribution of hyperphosphorylation to the activity of HSF1 remains unknown. In this study, we generated a phosphorylation-deficient HSF1 mutant (HSF1⌬ϳPRD), where the 15 known phosphorylation sites within the RD were disrupted. Our results show that the phosphorylation status of the RD does not affect the subcellular localization and DNA-binding activity of HSF1. Surprisingly, under stress conditions, HSF1⌬ϳPRD is a potent transactivator of both endogenous targets and a reporter gene, and HSF1⌬ϳPRD has a reduced activation threshold. Our results provide the first direct evidence for uncoupling stress-inducible phosphorylation of HSF1 from its activation, and we propose that the phosphorylation signature alone is not an appropriate marker for HSF1 activity.T he heat shock response, as characterized by inducible expression of heat shock proteins (Hsps), is an ancient, evolutionarily conserved mechanism that protects cells from various proteotoxic insults, including exposures to elevated temperatures, heavy metals, proteasome inhibition, and oxidative stress (1). Hsps function as molecular chaperones, bind to misfolded proteins, facilitate their refolding or direct them to degradation, and block the formation of protein aggregates (2, 3). The heat shock response is controlled by heat shock transcription factors (HSFs) (4). In vertebrates, four HSFs (HSF1 to HSF4) have been found, whereas yeasts, flies, and nematodes have only a single HSF. HSFs bind DNA at evolutionarily well-conserved sequences, consisting of inverted nGAAn repeats, called heat shock elements (5-8). HSF1 is considered the master regulator of the heat shock response in mammals, since mice lacking HSF1 are unable to induce Hsp expression upon exposure to protein-damaging stress (9, 10). Besides controlling the stress-inducible expression of Hsps, HSF1 plays a role in development (10-12), life span regulation (13-15), immune responses (16), and the circadian cycle (17). In addition, HSF1 is a well-recognized transcriptional regulator in malignant human cancers (18)(19)(20).The HSF1 protein is composed of five distinguishable functional domains (see Fig. 1A). The DNA-binding domain (DBD) is located at the N terminus (21), whereas the transactivation domain (TAD) resides in the C terminus (22). A unique requirement for HSF1 activation is the process of trimerization through an intermolecular interaction of leucine-zipper-like heptad repeat domains (HR-A/B) between HSF1...

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“…Enoki and Sakurai (2011) demonstrated that sequence differences in the HR-C domain of zebrafish HSF1a and HSF1c isoform affected oligomerization,which resulted in different binding affinities for discontinuous HSEs between the two isoforms. Recent studies of human and mice HSFs have demonstrated that different HSFs will recognize variations of HSE sequences, with HSF1 preferring a continuous inverted 5′nGAAn3′ repeat sequence while HSF2 and HSF4 are capable of binding to disordered versions of this sequence (Fujimoto et al 2008;Takemori et al 2009;Yamamoto et al 2009;Sakurai and Enoki 2010). In mouse lens tissue, 222 binding sites for HSF4 were identified, and of those binding sites, only six had perfect nGAAn repeats in the HSE sequences (Fujimoto et al 2008).…”

Section: Discussionmentioning

confidence: 99%

“…Takemori et al 2009 demonstrated that specific amino acid regions of the hHSF1 DBD and HR-A/B domain regulate the ability of HSF1 to bind to discontinuous HSE sequences. Enoki and Sakurai (2011) demonstrated that sequence differences in the HR-C domain of zebrafish HSF1a and HSF1c isoform affected oligomerization,which resulted in different binding affinities for discontinuous HSEs between the two isoforms.…”

Section: Discussionmentioning

confidence: 99%

Zebrafish HSF4: a novel protein that shares features of both HSF1 and HSF4 of mammals

Swan

Evans

Sylvain

et al. 2012

Cell Stress and Chaperones

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Heat-shock proteins (hsps) have important roles in the development of the eye lens. We previously demonstrated that knockdown of hsp70 gene expression using morpholino antisense technology resulted in an altered lens phenotype in zebrafish embryos. A less severe phenotype was seen with knockdown of heat-shock factor 1 (HSF1), suggesting that, while it likely plays a role in hsp70 regulation during lens formation, other regulatory factors are also involved. Heatshock factor 4 plays an important role in mammalian lens development, and an expressed sequence tag encoding zebrafish HSF4 has been identified. The deduced amino acid sequence shares structural similarities with mammalian HSF4 including the lack of an HR-C domain. However, the HR-C domain is absent due to a severe C-terminal truncation within zebrafish HSF4 (zHSF4) relative to the mammalian protein. Surprisingly, the amino acid composition of the zHSF4 DNA binding domain shares a greater degree of identity with HSF1 proteins than it does with mammalian HSF4 proteins. Consistent with this, the binding affinity of in vitro synthesized zHSF4 for discontinuous heat-shock response element sequences is more limited, similar to what has been previously observed for HSF1 proteins. Hsf4 mRNA is expressed in zebrafish adult eye tissue but is only observed in developing embryonic tissue at 60 h post-fertilization or later. This, together with the lack of an observable phenotype following morpholino-based antisense knockdown of hsf4, suggests that zHSF4 is unlikely to play a role in regulating early embryonic lens development.

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Mutational analysis of human heat-shock transcription factor 1 reveals a regulatory role for oligomerization in DNA-binding specificity

Cited by 16 publications

References 53 publications

The Response to Heat Shock and Oxidative Stress inSaccharomyces cerevisiae

The Response to Heat Shock and Oxidative Stress inSaccharomyces cerevisiae

Uncoupling Stress-Inducible Phosphorylation of Heat Shock Factor 1 from Its Activation

Zebrafish HSF4: a novel protein that shares features of both HSF1 and HSF4 of mammals

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