HSP70 and heat shock factor 1 cooperate to repress Ras-induced transcriptional activation of the c-fos gene

Diet changes alter paternally inherited epigenetic pattern in male Wild guinea pigs

Epigenetic modifications, of which DNA methylation is the most stable, are a mechanism conveying environmental information to subsequent generations via parental germ lines. The paternal contribution to adaptive processes in the offspring might be crucial, but has been widely neglected in comparison to the maternal one. To address the paternal impact on the offspring's adaptability to changes in diet composition, we investigated if low protein diet (LPD) in F0 males caused epigenetic alterations in their subsequently sired sons. We therefore fed F0 male Wild guinea pigs with a diet lowered in protein content (LPD) and investigated DNA methylation in sons sired before and after their father's LPD treatment in both, liver and testis tissues. Our results point to a 'heritable epigenetic response' of the sons to the fathers' dietary change. Because we detected methylation changes also in the testis tissue, they are likely to be transmitted to the F2 generation. Gene-network analyses of differentially methylated genes in liver identified main metabolic pathways indicating a metabolic reprogramming ('metabolic shift'). Epigenetic mechanisms, allowing an immediate and inherited adaptation may thus be important for the survival of species in the context of a persistently changing environment, such as climate change.

Extracellular Hsp70 Enhances Mesoangioblast Migration via an Autocrine Signaling Pathway

Mouse mesoangioblasts are vessel-associated progenitor stem cells endowed with the ability of multipotent mesoderm differentiation. Therefore, they represent a promising tool in the regeneration of injured tissues. Several studies have demonstrated that homing of mesoangioblasts into blood and injured tissues are mainly controlled by cytokines/chemokines and other inflammatory factors. However, little is known about the molecular mechanisms regulating their ability to traverse the extracellular matrix (ECM). Here, we demonstrate that membrane vesicles released by mesoangioblasts contain Hsp70, and that the released Hsp70 is able to interact by an autocrine mechanism with Toll-like receptor 4 (TLR4) and CD91 to stimulate migration. We further demonstrate that Hsp70 has a positive role in regulating matrix metalloproteinase 2 (MMP2) and MMP9 expression and that MMP2 has a more pronounced effect on cell migration, as compared to MMP9. In addition, the analysis of the intracellular pathways implicated in Hsp70 regulated signal transduction showed the involvement of both PI3K/AKT and NF-κB. Taken together, our findings present a paradigm shift in our understanding of the molecular mechanisms that regulate mesoangioblast stem cells ability to traverse the extracellular matrix (ECM). J. Cell. Physiol. 232: 1845-1861, 2017. © 2016 Wiley Periodicals, Inc.

Induction of Heat Shock Protein 70 Inhibits NF-kappa-B in Squamous Cell Carcinoma

OBJECTIVE: To determine the relationship between heat shock proteins (HSPs) and the proinflammatory, anti-apoptosis mediator NF-kappa-B in squamous cell carcinoma.

STUDY DESIGN AND SETTING: CA-9-22 cells were exposed to heat stress to induce the production of HSPs. Immunoblot and reporter gene experiments determined the inducibility of HSP production and the activation of cytokine-induced NF-kappa-B. Immunoblot experiments determined the presence of the inhibitor- k-B-α (I kBα).

RESULTS: CA-9-22 cells can be induced by heat stress to produce HSPs at 100-fold above baseline levels. The induction of HSPs prevents the activation and nuclear translocation of NF-kappa-B despite stimulation with IL-1β and TNF-α.

CONCLUSIONS: Constitutive activation of NF-kappa-B is prevented by HSP induction through an increase in I kBα synthesis.

SIGNIFICANCE: The induction of HSP70 alters the inflammatory milieu associated with squamous cell carcinoma progression through the inhibition of NF-kappa-B and may ultimately promote apoptosis in head and neck carcinoma.

Paternal heat exposure causes DNA methylation and gene expression changes of Stat3 in Wild guinea pig sons

Epigenetic mechanisms convey environmental information through generations and can regulate gene expression. Epigenetic studies in wild mammals are rare, but enable understanding adaptation processes as they may occur in nature. In most wild mammal species, males are the dispersing sex and thus often have to cope with differing habitats and thermal changes more rapidly than the often philopatric females. As temperature is a major environmental selection factor, we investigated whether genetically heterogeneous Wild guinea pig (Cavia aperea) males adapt epigenetically to an increase in temperature, whether that response will be transmitted to the next generation(s), and whether it regulates mRNA expression. Five (F0) adult male guinea pigs were exposed to an increased ambient temperature for 2 months, corresponding to the duration of the species' spermatogenesis. To study the effect of heat, we focused on the main thermoregulatory organ, the liver. We analyzed CpG‐methylation changes of male offspring (F1) sired before and after the fathers' heat treatment (as has recently been described in Weyrich et al. [Mol. Ecol., 2015]). Transcription analysis was performed for the three genes with the highest number of differentially methylated changes detected: the thermoregulation gene Signal Transducer and Activator of Transcription 3 (Stat3), the proteolytic peptidase gene Cathepsin Z (Ctsz), and Sirtuin 6 (Sirt6) with function in epigenetic regulation. Stat3 gene expression was significantly reduced (P < 0.05), which indicated a close link between CpG‐methylation and expression levels for this gene. The two other genes did not show gene expression changes. Our results indicate the presence of a paternal transgenerational epigenetic effect. Quick adaptation to climatic changes may become increasingly relevant for the survival of wildlife species as global temperatures are rising.

Genomic and phenotypic analysis reveals a key role for CCN1 (CYR61) in BAG3-modulated adhesion and invasion

Chaperone protein quantity may regulate the balance of proteins involved in invasion and malignancy. BAG3 is a co-chaperone and pro-survival protein that has been implicated in adhesion, migration, and metastasis. We reported that BAG3 overexpression in MDA435 human breast cancer cells results in a significant decrease in migration and adhesion to matrix molecules that is reversed upon deletion of the BAG3 proline-rich domain (dPXXP). We now hypothesize that transcriptional analysis would identify proteins involved in matrix-related processes that are regulated by BAG3 and/or its PXXP domain mutant. Expression array analysis of MDA435 cells overexpressing either wild-type BAG3 (FL) or dPXXP identified CCN1 as a BAG3 target protein. CCN1 is a known AP-1 target. Increased AP-1 transcriptional activity and AP-1 DNA-binding was found in MDA435 dPXXP cells. Consistent with these findings, CCN1 quantity and secretion were increased in dPXXP mutants but suppressed in FL cells; both BAG3 forms resulted in up-regulated CCN1 in HeLa cells. CCN1 silencing in the BAG3 FL overexpressors reduced the already low phospho-integrin beta1 in response to attachment on collagen IV. Matrigel invasion of HeLa cells engineered with the BAG3 constructs was enhanced in FL cells and minimal in dPXXP cells. CCN1 silencing blocked a greater percentage of the serum-induced invasion in FL cells than in dPXXP cells. This implies a context-dependent function of BAG3 on CCN1 and thus mesenchymal behaviour. CCN1 may be necessary for adhesion and matrix-related signalling in FL cells, abrogating a negative signal of the PXXP domain when BAG3 is intact. We propose that BAG3 regulates CCN1 expression to regulate tumour cell adhesion and migration.

CoREST represses the heat shock response mediated by HSF1

The stress response in cells involves a rapid and transient transcriptional activation of stress genes. It has been shown that Hsp70 limits its own transcriptional activation functioning as a corepressor of heat shock factor 1 (HSF1) during the attenuation of the stress response. Here we show that the transcriptional corepressor CoREST interacts with Hsp70. Through this interaction, CoREST represses both HSF1-dependent and heat shock-dependent transcriptional activation of the hsp70 promoter. In cells expressing short hairpin RNAs directed against CoREST, Hsp70 cannot repress HSF1-dependent transcription. A reduction of CoREST levels also provoked a significant increase of Hsp70 protein levels and an increase of HSF1-dependent transactivation of hsp70 promoter. Via chromatin immunoprecipitation assays we show that CoREST is bound to the hsp70 gene promoter under basal conditions and that its binding increases during heat shock response. In conclusion, we demonstrated that CoREST is a key regulator of the heat shock stress response.

Dual localization: proteins in extracellular and intracellular compartments

The goal of this article is to provide a comprehensive catalog of those proteins documented to exhibit dual localization, being found in both the extracellular compartment (cell surface and extracellular medium) as well as the intracellular compartment (cytosol and nucleus). A large subset of these proteins that show dual localization is found both in the nucleus and outside of cells. Proteins destined to be secreted out of the cell or to be expressed at the cell surface usually enter the endomembrane pathway on the basis of a signal sequence that targets them into the endoplasmic reticulum. Proteins destined for import into the nucleus, on the other hand, usually carry a nuclear localization signal. We have organized our catalog in terms of the presence and absence of these trafficking signals: (a) proteins that contain a signal sequence but no nuclear localization signal; (b) proteins that contain both a signal sequence as well as a nuclear localization signal; (c) proteins that contain a nuclear localization signal but lack a signal sequence; and (d) proteins containing neither a signal sequence nor a nuclear localization signal. Novel insights regarding the activities of several classes of proteins exhibiting dual localization can be derived when one targeting signal is experimentally abrogated. For example, the mitogenic activity of both fibroblasts growth factor-1 and schwannoma-derived growth factor clearly requires nuclear localization, independent of the activation of the receptor tyrosine kinase signaling pathway. In addition, there is a growing list of integral membrane receptors that undergo translocation to the nucleus, with bona fide nuclear localization signals and transcription activation activity. The information provided in this descriptive catalog will, hopefully, stimulate investigations into the pathways and mechanisms of transport between these compartments and the physiological significance of dual localization.

JWA as a novel molecule involved in oxidative stress-associated signal pathway in myelogenous leukemia cells

Previous data showed that JWA might be a novel environmental responsive gene regulated by environmental stressors such as heat shock and oxidative stress. However, the molecular mechanism underlying JWA gene function involved in oxidative stress is still unknown. In this study, the potential role of JWA was further investigated in hydrogen peroxide (H2O2) induced DNA damage and cell apoptosis in K562 cells. Series of the oxidative stress models were established to observe if JWA was involved in DNA damage or cell apoptosis induced by H2O2 exposure. These results indicated that the inhibitory effect on K562 cells' viability induced by H2O2 was concentration and time dependent. JWA was more sensitive to H2O2 (0.01 mmol/L) than the heat-shock proteins (hsp70 and hsp27), and its expression pattern was similar to that of hsp70. In addition, JWA, hsp70, hsp27, and p53 were overexpressed and the expression patterns of JWA, hsp70, and p53 were similar during cell apoptosis. H2O2 led to the cleavage and activation of procaspase-3. In conclusion, these results suggested that JWA might be an effective environmental responsive gene that functions as a parallel with hsp70 in oxidative stress-responsive pathways in K562 cells. Like hsp70, JWA might enhance intracellular defenses and function against H2O2-induced oxidative stress in leukemia cells. At the same time, JWA was involved in the p53-associated signal pathways of oxidative stress-induced apoptosis, which is also caspase-3 dependent.

Regulation of molecular chaperone gene transcription involves the serine phosphorylation, 14-3-3 epsilon binding, and cytoplasmic sequestration of heat shock factor 1

Heat shock factor 1 (HSF1) regulates the transcription of molecular chaperone hsp genes. However, the cellular control mechanisms that regulate HSF1 activity are not well understood. In this study, we have demonstrated for the first time that human HSF1 binds to the essential cell signaling protein 14-3-3 epsilon. Binding of HSF1 to 14-3-3 epsilon occurs in cells in which extracellular signal regulated kinase (ERK) is activated and blockade of the ERK pathway by treatment with the specific ERK pathway inhibitor PD98059 in vivo strongly suppresses the binding. We previously showed that ERK1 phosphorylates HSF1 on serine 307 and leads to secondary phosphorylation by glycogen synthase kinase 3 (GSK3) on serine 303 within the regulatory domain and that these phosphorylation events repress HSF1. We show here that HSF1 binding to 14-3-3 epsilon requires HSF1 phosphorylation on serines 303 and 307. Furthermore, the serine phosphorylation-dependent binding of HSF1 to 14-3-3 epsilon results in the transcriptional repression of HSF1 and its sequestration in the cytoplasm. Leptomycin B, a specific inhibitor of nuclear export receptor CRM1, was found to reverse the cytoplasmic sequestration of HSF1 mediated by 14-3-3 epsilon, suggesting that CRM1/14-3-3 epsilon directed nuclear export plays a major role in repression of HSF1 by the ERK/GSK3/14-3-3 epsilon pathway. Our experiments indicate a novel pathway for HSF1 regulation and suggest a mechanism for suppression of its activity during cellular proliferation.

Heat shock factor 1 contains two functional domains that mediate transcriptional repression of the c-fos and c-fms genes

Heat shock factor 1 (HSF1), in addition to its pivotal role as a regulator of the heat shock response, functions as a versatile gene repressor. We have investigated the structural domains involved in gene repression using mutational analysis of the hsf1 gene. Our studies indicate that HSF1 contains two adjacent sequences located within the N-terminal half of the protein that mediate the repression of c-fos and c-fms. One region (NF) appears to be involved in quenching transcriptional activation factors on target promoters and binds to the basic zipper transcription factor NF-IL6 required for activation of c-fms and IL-1beta. The NF domain encompasses the leucine zipper 1 and 2 sequences as well as the linker domain between the DNA binding and leucine zipper regions. The function of this domain in gene repression is highly specific for HSF1, and the homologous region from conserved family member HSF2 does not restore repressive function in HSF2/HSF1 chimeras. In addition, HSF2 is not capable of binding to NF-IL6. The NF domain, although necessary for repression, is not sufficient, and a second region (REP) occupying a portion of the regulatory domain is required for repression. Neither domain functions independently, and both are required for repression. Furthermore, we constructed dominant inhibitors of c-fos repression by HSF1, which also blocked the repression of c-fms and IL-1beta, suggesting a shared mechanism for repression of these genes by HSF1. Our studies suggest a complex mechanism for gene repression by HSF1 involving the binding to and quenching of activating factors on target promoters. Mapping the structural domains involved in this process should permit further characterization of molecular mechanisms that mediate repression.

Heat shock factor 1 represses transcription of the IL-1beta gene through physical interaction with the nuclear factor of interleukin 6

Heat shock factor (HSF) 1 is the major heat shock transcription factor that regulates stress-inducible synthesis of heat shock proteins and is also essential in protection against endotoxic shock. Following our previous study, which demonstrated the transcriptional repression of the IL-1beta gene by HSF1 (Cahill, C. M., Waterman, W. R., Xie, Y., Auron, P. E., and Calderwood, S. K. (1996) J. Biol. Chem. 271, 24874-24879), we have examined the mechanisms of transcriptional repression. Our studies show that HSF1 represses the lipopolyliposaccharide-induced transcription of the IL-1beta promoter through direct interaction with the nuclear factor of interleukin 6 (NF-IL6, also known as CCAAT enhancer binding protein (C/EBPbeta), an essential regulator in IL-1beta transcription. We show for the first time that HSF1 binds directly to NF-IL6 in vivo and antagonizes its activity. The HSF1/NF-IL6 interaction involves a sequence of HSF1 containing the trimerization and regulatory domains and the bZip region of NF-IL6. HSF1 has little effect on IL-1beta promoter activity stimulated by the essential monocytic transcription factor Spi.1 but is strongly inhibitory to transcriptional activation by NF-IL6 and to the synergistic activation by NF-IL6 and Spi.1. Because of its ability to bind to specific C/EBP elements in the promoters of multiple genes and its ability to interact with other transcription factors, NF-IL6 is involved in transcriptional regulation of a wide range of genes. Interaction between HSF1 and NF-IL6 could thus be an important mechanism in HSF1 regulation of general gene transcription during endotoxin stress.

Effect of manganese on heat stress protein synthesis of new-born rats

AIM: To study the effect of manganese (Mn) on heat stress protein 70 (HSP70) synthesis in the brain and liver of new-born rats whose mother-rats were exposed to Mn.

METHODS: 32 female rats were randomly divided into four groups. One group was administrated with physiological saline only as control group, the other three groups were administrated with 7.5, 15 and 30 mg·kg^-1 manganese chloride (MnCl₂) by intraperitioneal injection every two days for two weeks. After delivery, the mother-rats received MnCl₂ unceasingly for a week with the same method. Then the contents of Mn, Zn, Cu and Fe in the livers of the new-born rats were determined by atomic absorption spectroscopy; The level of HSP70 in the brains and the livers of the new-born rats as detected by Western-dot-blotting, and the SOD activities were measured simultaneously.

RESULTS: The contents of Mn in the livers of new-born rats of the experimental groups (respective 1.38 ± 0.18, 2.73 ± 0.65, 3.44 ± 0.89 μg·g^-1) were significantly increased compared with the control group (0.88 ± 0.18 μg·g^-1; P < 0.01); The contents of Fe in the livers of new-born rats of 15 and 30 mg·kg^-1 experimental groups (426 ± 125, 572 ± 175 μg·g^-1, respectively) were significantly increased compared with the control group(286 ± 42 μg·g^-1;P < 0.05); the levels of Zn in the livers of the new-born rats of three experimental groups(254 ± 49, 263 ± 47, 213 ± 28 μg·g^-1, respectively) were lower than those of the control group (335 ± 50 μg·g^-1; respective P < 0.05, P < 0.01); and the levels of Cu showed no significant difference among the four groups (three experimental groups: 75 ± 21, 68 ± 241 and 78 ± 18 μg·g^-1; control group: 83 ± 9 μg·g^-1; P > 0.05). There was a significant increase in the levels of HSP70 in the brains of new-born rats of the 30 mg·kg^-1 group (19.5 × 10³± 1.3 × 10³ A; control group: 14.3 × 10³± 1.4 × 10³A; P < 0.01),and the levels of HSP70 in the livers of new-born rats of three experimental groups(respective 19.6 × 10³± 3.9 × 10³A, 18.5 × 10³± 3.8 × 10³A, 22.4 × 10³± 1.9 × 10³A) also increased than control group(13.3 × 10³± 1.0 × 10³A; P < 0.01), but the SOD activities showed no significant difference among brains of the four groups (experimental groups: 5.04 ± 0.43, 4.83 ± 0.48, 4.60 ± 0.84 ku·g^-1; control group: 4.91 ± 0.37 ku·g^-1; P > 0.05). The SOD activities in the livers of 15 mg·kg^-1 group (5.41 ± 0.44 ku·g^-1) was lower than the control group(5.95 ± 0.36 ku·g^-1; P < 0.05).

CONCLUSION: While mother-rats were exposed to manganese, the metabolisms of Mn, Zn and Fe of new-born rats in the livers were influenced and were situated in a stress status, thus HSP70 syntheses is induced in the brains and livers of new-born rats, but the mechanism of this effect in the developmental toxicity of Mn remains to be further studied.