Transformation of eEF1Bδ into heat-shock response transcription factor by alternative splicing.
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ABSTRACT:
SUBMITTER: Kaitsuka T
PROVIDER: S-EPMC3128969 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Protein translation factors play crucial roles in a variety of stress responses. Here, we show that the eukaryotic elongation factor 1Bdelta (eEF1Bdelta) changes its structure and function from a translation factor into a heat shock response transcription factor by alternative splicing. While eEF1Bdelta is specifically localized in the cytoplasm, the long isoform of eEF1Bdelta (eEF1BdeltaL) is localized in the nucleus and induces heat shock element (HSE)-containing genes in cooperation with heat-shock transcription factor 1 (HSF1). Moreover, the N-terminal domain of eEF1BdeltaL binds with NF-E2-related factor 2 (Nrf2) and induces stress response heme oxygenase 1 (HO-1). Specific inhibition of eEF1BdeltaL with siRNA completely inhibits Nrf2-dependent HO-1 induction. In addition, eEF1BdeltaL directly binds to HSE oligo DNA in vitro and associates with HSE containing the HO-1-enhancer region in vivo. Thus, the transcriptional role of eEF1BdeltaL could provide new insights into the molecular mechanism of stress responses. We performed microarray analysis to compare the gene expression induced by eEF1Bdelta1 or eEF1BdeltaL overexpression.
2011-04-12 | GSE28506 | GEO
Project description:Protein translation factors play crucial roles in a variety of stress responses. Here, we show that the eukaryotic elongation factor 1Bdelta (eEF1Bdelta) changes its structure and function from a translation factor into a heat shock response transcription factor by alternative splicing. While eEF1Bdelta is specifically localized in the cytoplasm, the long isoform of eEF1Bdelta (eEF1BdeltaL) is localized in the nucleus and induces heat shock element (HSE)-containing genes in cooperation with heat-shock transcription factor 1 (HSF1). Moreover, the N-terminal domain of eEF1BdeltaL binds with NF-E2-related factor 2 (Nrf2) and induces stress response heme oxygenase 1 (HO-1). Specific inhibition of eEF1BdeltaL with siRNA completely inhibits Nrf2-dependent HO-1 induction. In addition, eEF1BdeltaL directly binds to HSE oligo DNA in vitro and associates with HSE containing the HO-1-enhancer region in vivo. Thus, the transcriptional role of eEF1BdeltaL could provide new insights into the molecular mechanism of stress responses. We performed microarray analysis to compare the gene expression induced by eEF1Bdelta1 or eEF1BdeltaL overexpression. HEK293 cells transfected with expression plasmids encoding flag-tagged-eEF1Bdelta1 or eEF1BdeltaL protein
2011-04-12 | E-GEOD-28506 | biostudies-arrayexpress
Project description:White-rot fungi, especially Trametes strains, are the primary source of industrial laccases in bioenergy and bioremediation. Trametes strains express members of the laccase gene family with different physicochemical properties and expression patterns. However, the literature on the expression pattern of the laccase gene family in T. trogii S0301 and the response mechanism to Cu2+, a key laccase inducer, in white-rot fungal strains is scarce. In the present study, we found that Cu2+ could induce the mRNAs and proteins of the two alternative splicing variants of heat shock transcription factor 2 (TtHSF2). Furthermore, the overexpression of alternative splicing variants TtHSF2α and TtHSF2β-I in the homokaryotic T. trogii S0301 strain showed opposite effects on the extracellular total laccase activity, with the maximum laccase activity of approximately 0.6 U mL-1 and 3.0 U mL-1, respectively, on the eighth day, which is 0.4 and 2.3 times that of the wild type strain. Similarly, TtHSF2α and TtHSF2β-I play opposite roles in the oxidation tolerance to H2O2 In addition, the direct binding of TtHSF2α to the promoter regions of the representative laccase isoenzymes (TtLac1 and TtLac13) and protein-protein interactions between TtHSF2α and TtHSF2β-I were detected. Our results demonstrate the crucial roles of TtHSF2 and its alternative splicing variants in response to Cu2+ We believe that these findings will deepen our understanding of alternative splicing of HSFs and their regulatory mechanism of the laccase gene family in white-rot fungi.Importance The members of laccase gene family in Trametes strains are the primary source of industrial laccase and have gained widespread attention. Increasing the yield and enzymatic properties of laccase through various methods has always been a topic worthy of attention, and there is no report on the regulation of laccase expression through HSF transcription factor engineering. Here, we found that two alternative splicing variants of TtHSF2 functioned oppositely in regulating the expression of laccase genes, and copper can induce the expression of almost all members of the laccase gene family. Most importantly, our study suggested that TtHSF2 and its alternative splicing variants are vital for copper-induced production of laccases in T. trogii S0301.
| S-EPMC8091107 | biostudies-literature
Project description:The heat shock response is an evolutionally conserved adaptive response to high temperatures that controls proteostasis capacity and is regulated mainly by an ancient heat shock factor (HSF). However, the regulation of target genes by the stress-inducible HSF1 transcription complex has not yet been examined in detail in mammalian cells. In the present study, we demonstrated that HSF1 interacted with members of the ATF1/CREB family involved in metabolic homeostasis and recruited them on the HSP70 promoter in response to heat shock. The HSF1 transcription complex, including the chromatin-remodeling factor BRG1 and lysine acetyltransferases p300 and CREB-binding protein (CBP), was formed in a manner that was dependent on the phosphorylation of ATF1. ATF1-BRG1 promoted the establishment of an active chromatin state and HSP70 expression during heat shock, whereas ATF1-p300/CBP accelerated the shutdown of HSF1 DNA-binding activity during recovery from acute stress, possibly through the acetylation of HSF1. Furthermore, ATF1 markedly affected the resistance to heat shock. These results revealed the unanticipated complexity of the primitive heat shock response mechanism, which is connected to metabolic adaptation.
| S-EPMC4295370 | biostudies-literature
Project description:The heat shock transcription factor Hsf1 of the yeast Saccharomyces cerevisiae regulates the transcription of a set of genes that contain heat shock elements (HSEs) in their promoters and function in diverse cellular processes, including protein folding. Here, we show that Hsf1 activates the transcription of various target genes when cells are treated with oxidizing reagents, including the superoxide anion generators menadione and KO(2) and the thiol oxidants diamide and 1-chloro-2,4-dinitrobenzene (CDNB). Similar to heat shock, the oxidizing reagents are potent inducers of both efficient HSE binding and extensive phosphorylation of Hsf1. The inducible phosphorylation of Hsf1 is regulated by the intramolecular domain-domain interactions and affects HSE structure-specific transcription. Unlike the heat shock, diamide, or CDNB response, menadione or KO(2) activation of Hsf1 is inhibited by cyclic-AMP-dependent protein kinase (PKA) activity, which negatively regulates the activator functions of other transcriptional regulators implicated in the oxidative stress response. These results demonstrate that Hsf1 is a member of the oxidative stress-responsive activators and that PKA is a general negative regulator in the superoxide anion response.
| S-EPMC1951129 | biostudies-literature
Project description:Previous work has implicated heat shock transcription factor 1 (HSF1) as the primary transcription factor responsible for the transcriptional response to heat stress in mammalian cells. We characterized the heat shock response of mammalian cells by measuring changes in transcript levels and assaying binding of HSF1 to promoter regions for candidate heat shock genes chosen by a combination of genome-wide computational and experimental methods. We found that many heat-inducible genes have HSF1 binding sites (heat shock elements, HSEs) in their promoters that are bound by HSF1. Surprisingly, for 24 heat-inducible genes, we detected no HSEs and no HSF1 binding. Furthermore, of 182 promoters with likely HSE sequences, we detected HSF1 binding at only 94 of these promoters. Also unexpectedly, we found 48 genes with HSEs in their promoters that are bound by HSF1 but that nevertheless did not show induction after heat shock in the cell types we examined. We also studied the transcriptional response to heat shock in fibroblasts from mice lacking the HSF1 gene. We found 36 genes in these cells that are induced by heat as well as they are in wild-type cells. These results provide evidence that HSF1 does not regulate the induction of every transcript that accumulates after heat shock, and our results suggest that an independent posttranscriptional mechanism regulates the accumulation of a significant number of transcripts.
| S-EPMC363119 | biostudies-literature
Project description:Translation elongation factor eEF1A has a well-defined role in protein synthesis. In this study, we demonstrate a new role for eEF1A: it participates in the entire process of the heat shock response (HSR) in mammalian cells from transcription through translation. Upon stress, isoform 1 of eEF1A rapidly activates transcription of HSP70 by recruiting the master regulator HSF1 to its promoter. eEF1A1 then associates with elongating RNA polymerase II and the 3'UTR of HSP70 mRNA, stabilizing it and facilitating its transport from the nucleus to active ribosomes. eEF1A1-depleted cells exhibit severely impaired HSR and compromised thermotolerance. In contrast, tissue-specific isoform 2 of eEF1A does not support HSR. By adjusting transcriptional yield to translational needs, eEF1A1 renders HSR rapid, robust, and highly selective; thus, representing an attractive therapeutic target for numerous conditions associated with disrupted protein homeostasis, ranging from neurodegeneration to cancer.
| S-EPMC4164936 | biostudies-literature
Project description:Pre-mRNA splicing is essential for the regulation of gene expression in eukaryotes and is fundamental in development and cancer, and involves the selection of a consensus sequence that defines the 5' splice site (5'SS). Human introns harbor multiple sequences that conform to the 5'SS consensus, which are not used under normal growth conditions. Under heat shock conditions, splicing at such intronic latent 5'SSs occurred in thousands of human transcripts, resulting in pre-maturely terminated aberrant proteins. Here we performed a survey of the C. elegans genome, showing that worm's introns contain latent 5'SSs, whose use for splicing would have resulted in pre-maturely terminated mRNAs. Splicing at these latent 5'SSs could not be detected under normal growth conditions, while heat shock activated latent splicing in a number of tested C. elegans transcripts. Two scenarios could account for the lack of latent splicing under normal growth conditions (i) Splicing at latent 5'SSs do occur, but the nonsense mRNAs thus formed are rapidly and efficiently degraded (e.g. by NMD); and (ii) Splicing events at intronic latent 5'SSs are suppressed. Here we support the second scenario, because, nematode smg mutants that are devoid of NMD-essential factors, did not show latent splicing under normal growth conditions. Hence, these experiments together with our previous experiments in mammalian cells, indicate the existence of a nuclear quality control mechanism, termed Suppression Of Splicing (SOS), which discriminates between latent and authentic 5'SSs in an open reading frame dependent manner, and allows splicing only at the latter. Our results show that SOS is an evolutionary conserved mechanism, probably shared by most eukaryotes.
| S-EPMC4615375 | biostudies-literature
Project description:The heat shock response (HSR) is characterized by the rapid and robust induction of heat shock proteins (HSPs), including HSP70, in response to heat shock and is regulated by heat shock transcription factor 1 (HSF1) in mammalian cells. Poly(ADP-ribose) polymerase 1 (PARP1), which can form a complex with HSF1 through the scaffold protein PARP13, has been suggested to be involved in the HSR. However, its effects on and the regulatory mechanisms of the HSR are not well understood. Here we show that prior to heat shock, the HSF1-PARP13-PARP1 complex binds to the HSP70 promoter. In response to heat shock, activated and auto-PARylated PARP1 dissociates from HSF1-PARP13 and is redistributed throughout the HSP70 locus. Remarkably, chromatin in the HSP70 promoter is initially PARylated at high levels and decondensed, whereas chromatin in the gene body is moderately PARylated afterwards. Activated HSF1 then binds to the promoter efficiently and promotes the HSR. Chromatin PARylation and HSF1 binding to the promoter are also facilitated by the phosphorylation-dependent dissociation of PARP13. Furthermore, the HSR and proteostasis capacity are reduced by pretreatment with genotoxic stresses, which disrupt the ternary complex. These results illuminate one of the priming mechanisms of the HSR that facilitates the binding of HSF1 to DNA during heat shock.
| S-EPMC6002698 | biostudies-literature
Project description:T-box (TBX) transcription factors are an ancient gene family with critical roles in embryogenesis. Currently, TBX3, TBX5, and TBX20 are TBX genes defined to have multiple protein isoforms created by alternative splicing and characterized by expression and functional studies. These proteins are important for development as mutations lead to severe developmental disorders in humans and mice. Cumulative studies suggest that alternative splicing of these genes can regulate TBX activities during multiple biological processes including cardiogenesis, limb development, and cancer mechanisms. This mini-review focuses on how alternative splicing adds complexity to transcriptional regulation of target genes controlled by TBX transcription factors.
| S-EPMC3171624 | biostudies-literature