Heat Shock Transcription Factor Research Articles

A Heat Shock Transcription Factor Gene (Hahsfa1) from a Desert Shrub, Haloxylon Ammodendron, Elevates Salt Tolerance in Arabidopsis Thaliana

A Heat Shock Transcription Factor Gene (Hahsfa1) from a Desert Shrub, Haloxylon Ammodendron, Elevates Salt Tolerance in Arabidopsis Thaliana

HSFA1d regulates the kinetics of heat-induced HSP17.6 expression in Arabidopsis.

Arabidopsis contains four HSFA1 heat shock transcription factors ( HSFA1a , HSFA1b , HSFA1d , and HSFA1e ) that regulate the primary response to high temperature stress responses. These genes have overlapping functions and, while double and triple HSFA1 mutants have thermotolerance phenotypes, these genes have no reported single mutant thermotolerance phenotypes. We used an automated fluorescence microscopy system to quantitate the expression of a HSP17. 6:GFP reporter with high temporal resolution to show that HSFA1d is required for normal heat-induced HSP17.6 expression. HSP17.6 expression is reduced and delayed in hsfa1d-1 mutants. This finding highlights the power of using gene expression kinetics as a quantitative phenotype for discovering the function of genes that exhibit functional redundancy.

Cloning and functional analysis of AaHSFB1 and its promoter in Amorphophallus

To explore the function of a heat shock transcription factor gene (HSFB1) and its promoter in Amorphophallus, a 1 365 bp DNA sequence was obtained by homologous cloning from Amorphophallus albus. The gene expression level of AaHSFB1 determined by qRT-PCR indicated that AaHSFB1 gene is more sensitive to heat stress. The expression level of AaHSFB1 in roots increased followed by a decrease upon heat treatment, and the highest expression level was observed after heat treatment for 1 h. The expression level of AaHSFB1 in leaves reached the highest after heat treatment for 12 h. The expression level in bulbs did not change greatly during the heat treatment. Subcellular localization analysis showed that AaHSFB1 protein was localized in the nucleus. A 1 509 bp DNA sequence which contains the AaHSFB1 promoter was obtained by FPNI-PCR method. Bioinformatics analysis showed that the promoter contained heat stress response elements HSE and a plurality of cis-acting elements related to plant development and stress response. A prAaHSFB1::GUS fusion expression vector was constructed to further analyze the function of AaHSFB1 promoter. The expression vector was transformed into Arabidopsis thaliana by Agrobacterium tumefaciens-mediated method, and GUS staining analysis on transgenic plants after heat treatment was performed. The results showed that AaHSFB1 promoter had very high activity in the leaves. Therefore, we speculate that AaHSFB1 may play an important role in the stress resistance of A. albus, especially when encountering heat stress.

Evolutionary and reverse engineering to increase Saccharomyces cerevisiae tolerance to acetic acid, acidic pH, and high temperature.

Saccharomyces cerevisiae scarcely grows on minimal media with acetic acid, acidic pH, and high temperatures. In this study, the adaptive laboratory evolution (ALE), whole-genome analysis, and reverse engineering approaches were used to generate strains tolerant to these conditions. The thermotolerant strain TTY23 and its parental S288C were evolved through 1year, in increasing concentrations of acetic acid up to 12g/L, keeping the pH ≤ 4. Of the 18 isolated strains, 9 from each ancestor, we selected the thermo-acid tolerant TAT12, derived from TTY23, and the acid tolerant AT22, derived from S288C. Both grew in minimal media with 12g/L of acetic acid, pH 4, and 30°C, and produced ethanol up to 29.25 ± 6mmol/gDCW/h-neither of the ancestors thrived in these conditions. Furthermore, only the TAT12 grew on 2g/L of acetic acid, pH 3, and 37°C, and accumulated 16.5 ± 0.5mmol/gDCW/h of ethanol. Whole-genome sequencing and transcriptomic analysis of this strain showed changes in the genetic sequence and transcription of key genes involved in the RAS-cAMP-PKA signaling pathway (RAS2, GPA2, and IRA2), the heat shock transcription factor (HSF1), and the positive regulator of replication initiation (SUM1), among others. By reverse engineering, the relevance of the combined mutations in the genes RAS2, HSF1, and SUM1 to the tolerance for acetic acid, low pH, and high temperature was confirmed. Alone, the RAS2 mutation yielded acid tolerance and HSF1 nutation thermotolerance. Increasing the thermo-acidic niche and acetic acid tolerance of S. cerevisiae can contribute to improve economic ethanol production. KEY POINTS: • Thermo-acid tolerant (TAT) yeast strains were generated by adaptive laboratory evolution. • The strain TAT12 thrived on non-native, thermo-acidic harmful conditions. • Mutations in RAS2, HSF1, and SUM1 genes rendered yeast thermo and acid tolerant.

De novo Whole-Genome Assembly of Moringa oleifera Helps Identify Genes Regulating Drought Stress Tolerance.

Abiotic stresses, especially drought stress, are responsible for heavy losses in productivity, which in turn poses an imminent threat for future food security. Understanding plants’ response to abiotic stress at the molecular level is crucially important for mitigating the impacts of climate change. Moringa oleifera is an important multipurpose plant with medicinal and nutritional properties and with an ability to grow in low water conditions, which makes the species an ideal candidate to study the regulatory mechanisms that modulate drought tolerance and its possible use in agroforestry system. In the present communication, we report whole-genome sequencing (WGS) of this species and assemble about 90% of the genome of M. oleifera var. Bhagya into 915 contigs with a N50 value of 4.7 Mb and predicted 32,062 putative protein-coding genes. After annotating the genome, we have chosen to study the heat shock transcription factor (HSF) family of genes to analyze their role in drought tolerance in M. oleifera. We predicted a total of 21 HSFs in the M. oleifera genome and carried out phylogenetic analyses, motif identification, analysis of gene duplication events, and differential expression of the HSF-coding genes in M. oleifera. Our analysis reveals that members of the HSF family have an important role in the plant’s response to abiotic stress and are viable candidates for further characterization.

MiR-541-3p suppresses gastric cancer via negative regulation of HSF1

Purpose: To explore the effects of miR-541-3P on the expression of heat shock transcription factor 1 (HSF1) in gastric cancer cells (GC).Methods: The MicroRNA Target Prediction Database was used to predict whether miR-541-3p interacts with HSF1. Interaction was assessed by dual-luciferase reporter assays. Furthermore, miR-541-3p mRNA levels in GC cell lines were determined by qRT-PCR. Human GC cell lines MKN45 and NCI-N87 were transfected with miR-541-3p mimic. Cell apoptosis, proliferation, invasion, and migration were evaluated using flow cytometry, apoptosis assays, Edu assays, CCK-8 assays, and transwell assays, respectively. Caspase-3, Bcl-2, and cleaved caspase-3 expression levels were determined by western blot.Results: Expression of miR-541-3p was significantly down-regulated in GC cells. Functionally, miR-541-3p mimic inhibited GC cell proliferation, migration, and invasion and induced apoptosis in vitro (p <0.01). Mechanistically, miR-541-3p interacted with HSF1 and inhibited its expression. Overexpression of HSF1 counteracted the effects of miR-541-3p mimic in GC cells.Conclusion: These results indicate that miR-541-3p suppresses the development of GC by targeting HSF1 and thus, is a possible strategy for for the management of GC.

Heat Shock Factor 1 Directly Regulates Postsynaptic Scaffolding PSD-95 in Aging and Huntington's Disease and Influences Striatal Synaptic Density.

PSD-95 (Dlg4) is an ionotropic glutamate receptor scaffolding protein essential in synapse stability and neurotransmission. PSD-95 levels are reduced during aging and in neurodegenerative diseases like Huntington’s disease (HD), and it is believed to contribute to synaptic dysfunction and behavioral deficits. However, the mechanism responsible for PSD-95 dysregulation under these conditions is unknown. The Heat Shock transcription Factor 1 (HSF1), canonically known for its role in protein homeostasis, is also depleted in both aging and HD. Synaptic protein levels, including PSD-95, are influenced by alterations in HSF1 levels and activity, but the direct regulatory relationship between PSD-95 and HSF1 has yet to be determined. Here, we showed that HSF1 chronic or acute reduction in cell lines and mice decreased PSD-95 expression. Furthermore, Hsf1(+/−) mice had reduced PSD-95 synaptic puncta that paralleled a loss in thalamo-striatal excitatory synapses, an important circuit disrupted early in HD. We demonstrated that HSF1 binds to regulatory elements present in the PSD-95 gene and directly regulates PSD-95 expression. HSF1 DNA-binding on the PSD-95 gene was disrupted in an age-dependent manner in WT mice and worsened in HD cells and mice, leading to reduced PSD-95 levels. These results demonstrate a direct role of HSF1 in synaptic gene regulation that has important implications in synapse maintenance in basal and pathological conditions.

Citrus heat shock transcription factor CitHsfA7-mediated citric acid degradation in response to heat stress.

Heat stress is a major abiotic stress for plants, which can generate a range of biochemical and genetic responses. In 'Ponkan' mandarin fruit, hot air treatment (HAT) accelerates the degradation of citric acid. However, the transcriptional regulatory mechanisms of citrate degradation in response to HAT remain to be elucidated. Here, 17 heat shock transcription factor sequences were isolated, and dual-luciferase assays were employed to investigate whether the encoded proteins that could trans-activate the promoters of key genes in the GABA shunt, involved in citrate metabolism. We identified four heat shock transcription factors (CitHsfA7, CitHsfA3, CitHsfA4b and CitHsfA8) that showed trans-activation effects on CitAco3, CitIDH3 and CitGAD4, respectively. Transient expression of the CitHsfs in citrus fruits indicated that CitHsfA7 was the only factor that resulted in a significant lowering of the citric acid content, and these results were confirmed by a virus-induced gene silencing system (VIGS). Sub-cellar localization showed that CitHsfA7 is located in the nucleus and is capable of binding directly to a putative HSE in the CitAco3 promoter and enhance its expression. We proposed that the induction of CitHsfA7 transcript level contributes to citric acid degradation in citrus fruit, via modulation of CitAco3 in response to HAT.

In Silico Characterization and Expression Profiles of Heat Shock Transcription Factors (HSFs) in Maize (Zea mays L.)

Heat shock transcription factors (HSFs) regulate many environmental stress responses and biological processes in plants. Maize (Zea mays L.) is a major cash crop that is grown worldwide. However, the growth and yield of maize are affected by several adverse environmental stresses. Therefore, investigating the factors that regulate maize growth and development and resistance to abiotic stress is an essential task for developing stress-resilient maize varieties. Thus, a comprehensive genome-wide identification analysis was performed to identify HSFs genes in the maize genome. The current study identified 25 ZmHSFs, randomly distributed throughout the maize genome. Phylogenetic analysis revealed that ZmHSFs are divided into three classes and 13 sub-classes. Gene structure and protein motif analysis supported the results obtained through the phylogenetic analysis. Segmental duplication is shown to be responsible for the expansion of ZmHSFs. Most of the ZmHSFs are localized inside the nucleus, and the ZmHSFs which belong to the same group show similar physio-chemical properties. Previously reported and publicly available RNA-seq analysis revealed a major role of class A HSFs including ZmHSFA-1a and ZmHSFA-2a in all the maize growth stages, i.e., seed, vegetative, and reproductive development. Under abiotic stress conditions (heat, drought, cold, UV, and salinity), members of class A and B ZmHSFs are induced. Gene ontology and protein–protein interaction analysis indicated a major role of ZmHSFs in resistance to environmental stress and regulation of primary metabolism. To summarize, this study provides novel insights for functional studies on the ZmHSFs in maize breeding programs.

De novo analysis reveals transcriptomic responses to heat stress in loquat leaves

AbstractTemperature has a vital impact on plant growth and development, and heat stress severely threatens agricultural productivity and food security. High temperatures can cause annual yield reductions and disease in loquat [Eriobotrya japonica (Thunb.) Lindl.]. However, the molecular mechanisms underlying the heat stress response in loquat are not known. In this study, the transcriptome of loquat leaves in response to heat stress was sequenced and assembled de novo, and differentially expressed genes (DEGs) were identified. A total of 16,120 and 11,668 DEGs were identified at 1 and 2 h posttreatment, respectively. Gene ontology (GO) analysis indicated that the DEGs were located in the membrane and endoplasmic reticulum and were related to signal transduction and protein modification. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that the heat‐induced DEGs were mainly related to the activation of protein processing in the endoplasmic reticulum and transcription. Ninety‐six heat shock proteins (HSPs) were also found in the protein processing pathway in the endoplasmic reticulum, and most HSPs were induced by heat stress. Heat shock transcription factors regulating the expression of downstream HSPs were induced by heat together with HSPs. This research provides insights into the mechanism of loquat plant heat stress tolerance and paves the way for heat‐tolerant loquat breeding.

β-Cyclocitral, a Master Regulator of Multiple Stress-Responsive Genes in Solanum lycopersicum L. Plants

β-cyclocitral (βCC), a major apocarotenoid of β-carotene, enhances plants’ defense against environmental stresses. However, the knowledge of βCC’s involvement in the complex stress-signaling network is limited. Here we demonstrate how βCC reprograms the transcriptional responses that enable Solanum lycopersicum L. (tomato) plants to endure a plethora of environmental stresses. Comparative transcriptome analysis of control and βCC-treated tomato plants was done by generating RNA sequences in the BGISEQ-500 platform. The trimmed sequences were mapped on the tomato reference genome that identifies 211 protein-coding differentially expressed genes. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis and their enrichment uncovered that only upregulated genes are attributed to the stress response. Moreover, 80% of the upregulated genes are functionally related to abiotic and biotic stresses. Co-functional analysis of stress-responsive genes revealed a network of 18 genes that code for heat shock proteins, transcription factors (TFs), and calcium-binding proteins. The upregulation of jasmonic acid (JA)-dependent TFs (MYC2, MYB44, ERFs) but not the JA biosynthetic genes is surprising. However, the upregulation of DREB3, an abscisic acid (ABA)-independent TF, validates the unaltered expression of ABA biosynthetic genes. We conclude that βCC treatment upregulates multiple stress-responsive genes without eliciting JA and ABA biosynthesis.

Regulation of defense responses via heat shock transcription factors in Cucumis sativus L. against Botrytis cinerea

Regulation of defense responses via heat shock transcription factors in Cucumis sativus L. against Botrytis cinerea

Expression of the Amorphophallus albus heat stress transcription factor AaHsfA1 enhances tolerance to environmental stresses in Arabidopsis

Amorphophallus is the only economic crop that can produce a large amount of glucomannan (KGM). However, heat stress can induce a variety of morphological and physiological changes in Amorphophallus, which also affects its growth, development, nutrition, and economic value. Heat shock transcription factors (Hsfs), as central regulators of the heat stress response, play a key role in protecting plants against heat stress and in regulating plant development. In this study, the AaHsfA1 gene was obtained from Amorphophallus albus, and sequence analysis confirmed that it was a typical class A Hsf. The qRT-PCR results demonstrated that AaHsfA1 was significantly upregulated in different tissues of Amorphophallus albus after heat stress. Meanwhile, allogenic transformation showed that AaHsfA1 could significantly improve the heat resistance of Arabidopsis under heat stress. Subcellular localization analysis revealed that AaHsfA1 localized to the nucleus and cytoplasm. Protein-protein interaction studies identified a direct interaction between AaHsfA1 and AaHsfA2a, AaHsfA1 and AaHsp70, but AaHsfA1 did not interact with AaHsfB1. In conclusion, this study provides theoretical and genetic references for analyzing the mechanism of Amorphophallus heat resistance formation and crop resistance breeding.

A Novel Heat Shock Transcription Factor (ZmHsf08) Negatively Regulates Salt and Drought Stress Responses in Maize.

Heat shock transcription factors (HSFs) play important roles in plant growth, development, and stress responses. However, the function of these transcription factors in abiotic stress responses in maize (Zea mays) remains largely unknown. In this study, we characterized a novel HSF transcription factor gene, ZmHsf08, from maize. ZmHsf08 was highly homologous to SbHsfB1, BdHsfB1, and OsHsfB1, and has no transcriptional activation activity. The expression profiles demonstrated that ZmHsf08 was differentially expressed in various organs of maize and was induced by salt, drought, and abscisic acid (ABA) treatment. Moreover, the overexpression of ZmHsf08 in maize resulted in enhanced sensitivity to salt and drought stresses, displaying lower survival rates, higher reactive oxygen species (ROS) levels, and increased malondialdehyde (MDA) contents compared with wild-type (WT) plants. Furthermore, RT-qPCR analyses revealed that ZmHsf08 negatively regulates a number of stress/ABA-responsive genes under salt and drought stress conditions. Collectively, these results indicate that ZmHsf08 plays a negative role in response to salt and drought stresses in maize.

ADH5-mediated NO bioactivity maintains metabolic homeostasis in brown adipose tissue.

SUMMARYBrown adipose tissue (BAT) thermogenic activity is tightly regulated by cellular redox status, but the underlying molecular mechanisms are incompletely understood. Protein S-nitrosylation, the nitric-oxide-mediated cysteine thiol protein modification, plays important roles in cellular redox regulation. Here we show that diet-induced obesity (DIO) and acute cold exposure elevate BAT protein S-nitrosylation, including UCP1. This thermogenic-induced nitric oxide bioactivity is regulated by S-nitrosoglutathione reductase (GSNOR; alcohol dehydrogenase 5 [ADH5]), a denitrosylase that balances the intracellular nitroso-redox status. Loss of ADH5 in BAT impairs cold-induced UCP1-dependent thermogenesis and worsens obesity-associated metabolic dysfunction. Mechanistically, we demonstrate that Adh5 expression is induced by the transcription factor heat shock factor 1 (HSF1), and administration of an HSF1 activator to BAT of DIO mice increases Adh5 expression and significantly improves UCP1-mediated respiration. Together, these data indicate that ADH5 controls BAT nitroso-redox homeostasis to regulate adipose thermogenesis, which may be therapeutically targeted to improve metabolic health.

Targeting of HSP70/HSF1 Axis Abrogates In Vitro Ibrutinib-Resistance in Chronic Lymphocytic Leukemia.

Simple SummaryThe use of ibrutinib has changed the management and clinical history of patients with multiple-treated chronic lymphocytic leukemia (CLL). Nevertheless, an increasing number of patients develop resistance to treatment, with mechanisms still to be fully clarified. Since HSP70 plays a pivotal role in mediating the survival and the progression of CLL, we herein addressed the role of HSP70 and its regulator HSF1 in the development of ibrutinib-mediated resistance. We found an increase in both proteins when the treatment was failing, and thus the disease was progressing. This suggests the involvement of HSP70 in mechanisms of drug resistance. Moreover, we demonstrated that the use, at different levels, of HSP70/HSF1 axis inhibitors could represent a novel rational therapeutic approach to overcome ibrutinib resistance in those patients who relapsed after this type of treatment.The Btk inhibitor ibrutinib has significantly changed the management of chronic lymphocytic leukemia (CLL) patients. Despite its clinical efficacy, relapses occur, and outcomes after ibrutinib failure are poor. Although BTK and PLCγ2 mutations have been found to be associated with ibrutinib resistance in a fair percentage of CLL patients, no information on resistance mechanisms is available in patients lacking these mutations. The heat shock protein of 70 kDa (HSP70) and its transcription factor heat shock factor 1 (HSF1) play a role in mediating the survival and progression of CLL, as well as taking part in drug resistance in various cancers. We demonstrated that resveratrol and related phenols were able to induce apoptosis in vitro in leukemic cells from CLL untreated patients by acting on the HSP70/HSF1 axis. The same was achieved in cells recovered from 13 CLL patients failing in vivo ibrutinib treatment. HSP70 and HSF1 levels decreased following in vitro treatment, correlating to apoptosis induction. We suggest an involvement of HSP70/HSF1 axis in controlling resistance to ibrutinib in CLL cells, since their inhibition is effective in inducing in vitro apoptosis in cells from ibrutinib refractory patients. The targeting of HSP70/HSF1 axis could represent a novel rational therapeutic strategy for CLL, also for relapsing patients.

Application of CD83 and HSF5 to Identify Antemortem and Postmortem Skin Burns.

To explore the forensic application value of cluster of differentiation 83 (CD83) and heat shock transcription factor 5(HSF5) in identifying antemortem and postmortem skin burns. Through reverse transcription real-time quantitative polymerase chain reaction (RT-qPCR), CD83 and HSF5 mRNA levels in the skin tissues of antemortem and postmortem burned mice and human samples were detected quantitatively. Compared with the control group and the postmortem burned group, the mRNA levels of CD83 and HSF5 in antemortem burned mice were higher. The high mRNA expressions of CD83 could be detected 96 h after death, and the mRNA expressions of HSF5 could be observed 72 h after death. Compared with undamaged skin, increased CD83 and HSF5 mRNA levels were detected in 11 out of 15 cases(P<0.05). CD83 and HSF5 can be used in forensic practice as indicators for vital reaction in antemortem burn identification.

Transcriptome Analysis of Lolium temulentum Exposed to a Combination of Drought and Heat Stress.

Drought and heat are two major stresses predicted to increase in the future due to climate change. Plants exposed to multiple stressors elicit unique responses from those observed under individual stresses. A comparative transcriptome analysis of Lolium temulentum exposed to drought plus heat and non-stressed control plants revealed 20,221 unique up-regulated and 17,034 unique down-regulated differentially regulated transcripts. Gene ontology analysis revealed a strong emphasis on transcriptional regulation, protein folding, cell cycle/parts, organelles, binding, transport, signaling, oxidoreductase, and antioxidant activity. Differentially expressed genes (DEGs) encoding for transcriptional control proteins such as basic leucine zipper, APETALA2/Ethylene Responsive Factor, NAC, and WRKY transcription factors, and Zinc Finger (CCCH type and others) proteins were more often up-regulated, while DEGs encoding Basic Helix-Loop-Helix, MYB and GATA transcription factors, and C2H2 type Zinc Finger proteins were more often down-regulated. The DEGs encoding heat shock transcription factors were only up-regulated. Of the hormones, auxin-related DEGs were the most prevalent, encoding for auxin response factors, binding proteins, and efflux/influx carriers. Gibberellin-, cytokinin- and ABA-related DEGs were also prevalent, with fewer DEGs related to jasmonates and brassinosteroids. Knowledge of genes/pathways that grasses use to respond to the combination of heat/drought will be useful in developing multi-stress resistant grasses.

Gene bookmarking by the heat shock transcription factor programs the insulin-like signaling pathway

Maternal stress can have long-lasting epigenetic effects on offspring. To examine how epigenetic changes are triggered by stress, we examined the effects of activating the universal stress-responsive heat shock transcription factor HSF-1 in the germline of Caenorhabditis elegans. We show that, when activated in germ cells, HSF-1 recruits MET-2, the putative histone 3 lysine 9 (H3K9) methyltransferase responsible for repressive H3K9me2 (H3K9 dimethyl) marks in chromatin, and negatively bookmarks the insulin receptor daf-2 and other HSF-1 target genes. Increased H3K9me2 at these genes persists in adult progeny and shifts their stress response strategy away from inducible chaperone expression as a mechanism to survive stress and instead rely on decreased insulin/insulin growth factor (IGF-1)-like signaling (IIS). Depending on the duration of maternal heat stress exposure, this epigenetic memory is inherited by the next generation. Thus, paradoxically, HSF-1 recruits the germline machinery normally responsible for erasing transcriptional memory but, instead, establishes a heritable epigenetic memory of prior stress exposure.

Upregulation of heat shock transcription factors, Hsp70, and defense-related genes in heat shock-induced resistance against powdery mildew in cucumber

This study investigated heat shock-induced resistance (HSIR) against cucumber powdery mildew and confirmed the initial mechanism of HSIR prior to systemic acquired resistance. Heat shock treatment reduced the disease index of powdery mildew when the inoculation period was 24 h or less. HSIR increased the gene expression of Hsp70 12 h after the treatment, while the gene expression levels of POX and LOX6 increased 24 h after the treatment. Heat shock element (HSE) motifs were found in the promoter area of these target genes. The gene expression levels of HsfA2, HsfB1, and HsfB4 increased 6 h after heat shock. Therefore, upon heat stress, some heat shock transcription factors were activated to bind to HSEs and upregulate the transcription of Hsp70 and defense-related genes.