Regulation of cyclooxygenase-2 expression by heat: a novel aspect of heat shock factor 1 function in human cells

Human coronaviruses activate and hijack the host transcription factor HSF1 to enhance viral replication

Organisms respond to proteotoxic-stress by activating the heat-shock response, a cellular defense mechanism regulated by a family of heat-shock factors (HSFs); among six human HSFs, HSF1 acts as a proteostasis guardian regulating severe stress-driven transcriptional responses. Herein we show that human coronaviruses (HCoV), both low-pathogenic seasonal-HCoVs and highly-pathogenic SARS-CoV-2 variants, are potent inducers of HSF1, promoting HSF1 serine-326 phosphorylation and triggering a powerful and distinct HSF1-driven transcriptional-translational response in infected cells. Despite the coronavirus-mediated shut-down of the host translational machinery, selected HSF1-target gene products, including HSP70, HSPA6 and AIRAP, are highly expressed in HCoV-infected cells. Using silencing experiments and a direct HSF1 small-molecule inhibitor we show that, intriguingly, HCoV-mediated activation of the HSF1-pathway, rather than representing a host defense response to infection, is hijacked by the pathogen and is essential for efficient progeny particles production. The results open new scenarios for the search of innovative antiviral strategies against coronavirus infections.

Indomethacin inhibits human seasonal coronaviruses at late stages of viral replication in lung cells: Impact on virus-induced COX-2 expression

Coronaviruses (CoV), zoonotic viruses periodically emerging worldwide, represent a constant potential threat to humans. To date, seven human coronaviruses (HCoV) have been identified: HCoV-229E, HCoV-NL63, HCoV-OC43 and HCoV-HKU1, globally circulating in the human population (seasonal coronaviruses, sHCoV), and three highly-pathogenic coronaviruses, SARS-CoV, MERS-CoV and SARS-CoV-2. Although sHCoV generally cause only mild respiratory diseases, severe complications may occur in specific populations, highlighting the need for broad-spectrum anti-coronavirus drugs. Herein we show that indomethacin (INDO), a non-steroidal anti-inflammatory drug widely used in the clinic for its potent anti-inflammatory and analgesic properties, effectively inhibits the replication of Alpha-coronavirus HCoV-229E and Beta-coronavirus HCoV-OC43 in human lung-derived cells. Indomethacin does not interfere with HCoV binding or entry into target cells, but acts at late stages of the virus life cycle, inhibiting viral RNA synthesis and infectious viral particles production. Although INDO anti-inflammatory action is mediated by blocking cyclooxygenase-1 and -2 (COX-1/2) enzymatic activity, the antiviral effect appears to be cyclooxygenase-independent and is not mimicked by the potent COX-1/2 inhibitor aspirin. Interestingly we found that both seasonal HCoVs markedly (>100 fold) induce the expression of the pro-inflammatory mediator COX-2 in lung cells; notably, INDO-treatment was found to effectively inhibit virus-induced COX-2 expression at the transcriptional level, revealing an additional mechanism to prevent COX-2-mediated inflammatory reactions in HCoV-infected lung cells, besides COX activity inhibition. Altogether the results indicate that indomethacin, possessing both potent anti-inflammatory properties and a direct antiviral activity against HCoV, could be effective in the treatment of Alpha- and Beta-coronavirus infections.

Effect of heat exposure on prostaglandin production and expression of COX-2, PGES, PGFS, ITGAV and LGALS15 mRNAs in endometrial epithelial cells of buffalo (Bubalus bubalis)

BACKGROUND

Early embryonic mortality is one of the major intriguing factors of reproductive failure that causes considerable challenge to the mammalian cell biologists. Heat stress is the major factor responsible for reduced fertility in farm animals. The present study aimed to investigate the influence of heat stress on prostaglandin production and the expression of key genes, including COX-2, PGES, PGFS, ITGAV and LGALS15, in buffalo endometrial epithelial cells.

METHODS AND RESULTS

Buffalo genitalia containing ovaries with corpus luteum (CL) were collected immediately post-slaughter. The stages of the estrous cycle were determined based on macroscopic observations of the ovaries. Uterine lumens of the mid-luteal phase (days 6-10 of the estrous cycle) were washed and treated with trypsin to isolate epithelial cells, which were then cultured at control temperature (38.5 °C for 24 h) or exposed to elevated temperatures [38.5 °C for 6 h, 40.5 °C for 18 h; Heat Stressed (HS)]. The supernatant and endometrial epithelial cells were collected at various time points (0, 3, 6, 12, and 24 h) from both the control and treatment groups. Although heat stress (40.5 °C) significantly (P < 0.05) increased COX-2, PGES, and PGFS transcripts in epithelial cells but it did not affect the in vitro production of PGF2α and PGE2. The expression of ITGAV and LGALS15 mRNAs in endometrial epithelial cells remained unaltered under elevated temperature conditions.

CONCLUSION

It can be concluded that elevated temperature did not directly modulate prostaglandin production but, it promoted the expression of COX-2, PGES and PGFS mRNA in buffalo endometrial epithelial cells.

Heat shock response during the resolution of inflammation and its progressive suppression in chronic-degenerative inflammatory diseases

The heat shock response (HSR) is a crucial biochemical pathway that orchestrates the resolution of inflammation, primarily under proteotoxic stress conditions. This process hinges on the upregulation of heat shock proteins (HSPs) and other chaperones, notably the 70 kDa family of heat shock proteins, under the command of the heat shock transcription factor-1. However, in the context of chronic degenerative disorders characterized by persistent low-grade inflammation (such as insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases) a gradual suppression of the HSR does occur. This work delves into the mechanisms behind this phenomenon. It explores how the Western diet and sedentary lifestyle, culminating in the endoplasmic reticulum stress within adipose tissue cells, trigger a cascade of events. This cascade includes the unfolded protein response and activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome, leading to the emergence of the senescence-associated secretory phenotype and the propagation of inflammation throughout the body. Notably, the activation of the NOD-like receptor pyrin domain-containing protein-3 inflammasome not only fuels inflammation but also sabotages the HSR by degrading human antigen R, a crucial mRNA-binding protein responsible for maintaining heat shock transcription factor-1 mRNA expression and stability on heat shock gene promoters. This paper underscores the imperative need to comprehend how chronic inflammation stifles the HSR and the clinical significance of evaluating the HSR using cost-effective and accessible tools. Such understanding is pivotal in the development of innovative strategies aimed at the prevention and treatment of these chronic inflammatory ailments, which continue to take a heavy toll on global health and well-being.

The dance of proteostasis and metabolism: Unveiling the caloristatic controlling switch

The heat shock response (HSR) is an ancient and evolutionarily conserved mechanism designed to restore cellular homeostasis following proteotoxic challenges. However, it has become increasingly evident that disruptions in energy metabolism also trigger the HSR. This interplay between proteostasis and energy regulation is rooted in the fundamental need for ATP to fuel protein synthesis and repair, making the HSR an essential component of cellular energy management. Recent findings suggest that the origins of proteostasis-defending systems can be traced back over 3.6 billion years, aligning with the emergence of sugar kinases that optimized glycolysis around 3.594 billion years ago. This evolutionary connection is underscored by the spatial similarities between the nucleotide-binding domain of HSP70, the key player in protein chaperone machinery, and hexokinases. The HSR serves as a hub that integrates energy metabolism and resolution of inflammation, further highlighting its role in maintaining cellular homeostasis. Notably, 5'-adenosine monophosphate-activated protein kinase emerges as a central regulator, promoting the HSR during predominantly proteotoxic stress while suppressing it in response to predominantly metabolic stress. The complex relationship between 5'-adenosine monophosphate-activated protein kinase and the HSR is finely tuned, with paradoxical effects observed under different stress conditions. This delicate equilibrium, known as caloristasis, ensures that cellular homeostasis is maintained despite shifting environmental and intracellular conditions. Understanding the caloristatic controlling switch at the heart of this interplay is crucial. It offers insights into a wide range of conditions, including glycemic control, obesity, type 2 diabetes, cardiovascular and neurodegenerative diseases, reproductive abnormalities, and the optimization of exercise routines. These findings highlight the profound interconnectedness of proteostasis and energy metabolism in cellular function and adaptation.

Indirect effects of interference of two emerging environmental contaminants on cell health: Radiofrequency radiation and gold nanoparticles

BACKGROUND

The global need for wireless technologies is growing rapidly. So, we have been exposed to a new type of environmental pollution: radiofrequency radiation (RFR). Recent studies have shown that RFR can cause not only direct effects but also indirect or non-targeted effects such as the bystander effect (BE). In this study, we investigated the BE induced by RFR in the present of gold nanoparticles (GNP). Moreover, we studied the expression of cyclooxygenase-2 (COX-2).

METHODS

Non-toxic dose of 15-nm GNP was used to treat the Chinese Hamster Ovary (CHO) cells. After 48 h of incubation, cells were exposed to 900 MHz GSM RFR for 24 h. Then we collected the cell culture medium of these cells (conditioned culture medium, CCM) and transferred it to new cells (bystander cells). Cell deaths, DNA breaks, oxidative stress and COX-2 expression were analyzed in all groups.

RESULTS

The results showed that RFR increased metabolic death in cells treated with GNP. Inversely, the colony formation ability was reduced in bystander cells and RFR exposed cells either in the presence or absence of GNP. Also, the level of reactive oxygen species (ROS) in GNP treated cells showed a significant reduction compared to those of untreated cells. However, RFR-induced DNA breaks and the frequencies of micronuclei (MN) were not significantly affected by GNP. The expression of COX-2 mRNA increased in RFR GNP treated cells, but the difference was not significant.

CONCLUSION

Our results for the first time indicated that RFR induce indirect effects in the presence of GNP. However, the molecular mediators of these effects differ from those in the absence of GNP. Also, to our knowledge, this is the first study to show that COX-2 is not involved in the bystander effect induced by 900 MHz RFR.

Screening and Structural Characterization of Heat Shock Response Elements (HSEs) in Entamoeba histolytica Promoters

Entamoeba histolytica (E. histolytica) exhibits a remarkable capacity to respond to thermal shock stress through a sophisticated genetic regulation mechanism. This process is carried out via Heat Shock Response Elements (HSEs), which are recognized by Heat Shock Transcription Factors (EhHSTFs), enabling fine and precise control of gene expression. Our study focused on screening for HSEs in the promoters of the E. histolytica genome, specifically analyzing six HSEs, including Ehpgp5, EhrabB1, EhrabB4, EhrabB5, Ehmlbp, and Ehhsp100. We discovered 2578 HSEs, with 1412 in promoters of hypothetical genes and 1166 in coding genes. We observed that a single promoter could contain anywhere from one to five HSEs. Gene ontology analysis revealed the presence of HSEs in essential genes for the amoeba, including cysteine proteinases, ribosomal genes, Myb family DNA-binding proteins, and Rab GTPases, among others. Complementarily, our molecular docking analyses indicate that these HSEs are potentially recognized by EhHSTF5, EhHSTF6, and EhHSTF7 factors in their trimeric conformation. These findings suggest that E. histolytica has the capability to regulate a wide range of critical genes via HSE-EhHSTFs, not only for thermal stress response but also for vital functions of the parasite. This is the first comprehensive study of HSEs in the genome of E. histolytica, significantly contributing to the understanding of its genetic regulation and highlighting the complexity and precision of this mechanism in the parasite's survival.

Duodenal Metabolic Profile Changes in Heat-Stressed Broilers

Simple Summary

Heat stress (HS) represents an environmental and socio-economic burden to the poultry industry worldwide. However, the underpinning mechanisms for HS responses are still not well defined. Here, we used a high-throughput analysis to determine the metabolite profiles in acute and chronic heat-stressed broilers in comparison with thermoneutral and pair-fed birds. The results showed that HS altered several duodenal metabolites in a duration-dependent manner and identified potential metabolite signatures.

Abstract

Heat stress (HS) is devastating to poultry production sustainability worldwide. In addition to its adverse effects on growth, welfare, meat quality, and mortality, HS alters the gut integrity, leading to dysbiosis and leaky gut syndrome; however, the underlying mechanisms are not fully defined. Here, we used a high-throughput mass spectrometric metabolomics approach to probe the metabolite profile in the duodenum of modern broilers exposed to acute (AHS, 2 h) or chronic cyclic (CHS, 8 h/day for 2 weeks) HS in comparison with thermoneutral (TN) and pair-fed birds. Ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC–HRMS) identified a total of 178 known metabolites. The trajectory analysis of the principal component analysis (PCA) score plots (both 2D and 3D maps) showed clear separation between TN and each treated group, indicating a unique duodenal metabolite profile in HS birds. Within the HS groups, partial least squares discriminant analysis (PLS-DA) displayed different clusters when comparing metabolite profiles from AHS and CHS birds, suggesting that the metabolite signatures were also dependent on HS duration. To gain biologically related molecule networks, the above identified duodenal metabolites were mapped into the Ingenuity Pathway Analysis (IPA) knowledge-base and analyzed to outline the most enriched biological functions. Several common and specific top canonical pathways were generated. Specifically, the adenosine nucleotide degradation and dopamine degradation pathways were specific for the AHS group; however, the UDP-D-xylose and UDP-D-glucuronate biosynthesis pathways were generated only for the CHS group. The top diseases enriched by the IPA core analysis for the DA metabolites, including cancer, organismal (GI) injury, hematological, cardiovascular, developmental, hereditary, and neurological disorders, were group-specific. The top altered molecular and cellular functions were amino acid metabolism, molecular transport, small molecule biochemistry, protein synthesis, cell death and survival, and DNA damage and repair. The IPA-causal network predicted that the upstream regulators (carnitine palmitoyltransferase 1B, CPT1B; histone deacetylase 11, HDAC11; carbonic anhydrase 9, CA9; interleukin 37, IL37; glycine N-methyl transferase, GNMT; GATA4) and the downstream mediators (mitogen-activated protein kinases, MAPKs; superoxide dismutase, SOD) were altered in the HS groups. Taken together, these data showed that, independently of feed intake depression, HS induced significant changes in the duodenal metabolite profile in a duration-dependent manner and identified a potential duodenal signature for HS.

The Effects of Heat Shock Protein 70 Addition in the Culture Medium on the Development and Quality of In Vitro Produced Heat Shocked Bovine Embryos

The aims of the present study were to examine the effects of HSP70 addition in the in vitro culture medium of day 3 embryos on their developmental competence and quality. Bovine oocytes (n = 1442) were in vitro matured, inseminated and cultured for the first two days according to standardized methods. The presumptive zygotes were randomly allocated in three experimental groups: Control, C (embryos cultured at 39 °C throughout the culture period), group C41 (temperature was raised to 41 °C from the 48th to 72nd h post insemination (p.i.) and then it returned at 39 °C for the remaining culture period), and group H41 (the temperature modification was the same as in C41 and during heat exposure, HSP70 was added in the culture medium). Cleavage and embryo yield were assessed 48 h p.i. and on days 7, 8, 9, respectively and gene expression in day 7 blastocysts was assessed by RT-PCR. Blastocyst yield was the highest in group C39; and higher in group H41 compared to group C41. From the gene expression analyses, altered expression of 11 genes was detected among groups. The analysis of the orchestrated patterns of gene expression differed between groups. The results of this study confirm the devastating effects of heat stress on embryo development and provide evidence that HSP70 addition at the critical stages can partly counterbalance, without neutralizing, the negative effects of the heat insult on embryos, acting mainly through mechanisms related to energy deployment.

Fever and breast cancer: A critical review of the literature and possible underlying mechanisms

Fever is a common feature in various pathological conditions that manifests a series of molecular events in the internal milieu. Much less attention has been paid to the clinical importance and the management of fever in breast cancer patients. However, several studies have reported an association between postoperative fever and poor treatment outcomes in breast cancer patients. The fever is a side effect of chemotherapy and a manifestation of cancer recurrence. The postmenopausal breast cancer patients experience another body temperature disturbance that is known as a hot flashes. Here, we reviewed the literature regarding postoperative fever and the possible underlying molecular and cellular mechanisms. Then the efficacy of non-steroidal anti-inflammatory drugs was discussed as a therapeutic option to control postoperative fever. Finally, we reviewed the chemotherapy-induced neutropenic fever and cancer vaccination-induced fever.

Heat stress on cattle embryo: gene regulation and adaptation

Global warming has been affecting animal husbandry and farming production worldwide via changes in organisms and their habitats. In the tropics, these conditions are adverse for agriculture and animal production in some areas, due to high temperatures and relative humidity, affecting competitiveness related to economic activities. These environments have deteriorated livestock production, due to periods of drought, reduction in forage quality and heat stress, eliciting negative effects on reproduction, weight gain, and reduced meat and milk production. However, the use of animals adapted to tropics such as breeds derived from subspecies Bos primigenius indicus and native breeds from tropical countries or their crossings, is an alternative to improve production under high-temperature conditions. Therefore, physiological adaptation including gene expression induced by heat stress have been studied to understand the response of animals and to improve cross-breeding between cattle breeds to maintain high productivity in adverse weather conditions. Heat stress has been associated with lower reproductive performance in cows, due to the impact on blastocyst production, decreased implantation and increased embryonic death. Thus, for decades, in vitro fertilization and embryo transfer techniques have focused on studying the optimal conditions for production of high-quality embryos to transfer. The aim of this review is to discuss the effects of heat stress in bovine embryos, and their physiological and genetic modulation, focusing on the genes that are related with major adaptability to heat stress conditions and their relationship with different embryonic stages.

The proteostasis guardian HSF1 directs the transcription of its paralog and interactor HSF2 during proteasome dysfunction

Protein homeostasis is essential for life in eukaryotes. Organisms respond to proteotoxic stress by activating heat shock transcription factors (HSFs), which play important roles in cytoprotection, longevity and development. Of six human HSFs, HSF1 acts as a proteostasis guardian regulating stress-induced transcriptional responses, whereas HSF2 has a critical role in development, in particular of brain and reproductive organs. Unlike HSF1, that is a stable protein constitutively expressed, HSF2 is a labile protein and its expression varies in different tissues; however, the mechanisms regulating HSF2 expression remain poorly understood. Herein we demonstrate that the proteasome inhibitor anticancer drug bortezomib (Velcade), at clinically relevant concentrations, triggers de novo HSF2 mRNA transcription in different types of cancers via HSF1 activation. Similar results were obtained with next-generation proteasome inhibitors ixazomib and carfilzomib, indicating that induction of HSF2 expression is a general response to proteasome dysfunction. HSF2-promoter analysis, electrophoretic mobility shift assays, and chromatin immunoprecipitation studies unexpectedly revealed that HSF1 is recruited to a heat shock element located at 1.397 bp upstream from the transcription start site in the HSF2-promoter. More importantly, we found that HSF1 is critical for HSF2 gene transcription during proteasome dysfunction, representing an interesting example of transcription factor involved in controlling the expression of members of the same family. Moreover, bortezomib-induced HSF2 was found to localize in the nucleus, interact with HSF1, and participate in bortezomib-mediated control of cancer cell migration. The results shed light on HSF2-expression regulation, revealing a novel level of HSF1/HSF2 interplay that may lead to advances in pharmacological modulation of these fundamental transcription factors.

Redefining proteostasis transcription factors in organismal stress responses, development, metabolism, and health

Eukaryotic organisms have evolved complex and robust cellular stress response pathways to ensure maintenance of proteostasis and survival during fluctuating environmental conditions. Highly conserved stress response pathways can be triggered and coordinated at the cell-autonomous and cell-nonautonomous level by proteostasis transcription factors, including HSF1, SKN-1/NRF2, HIF1, and DAF-16/FOXO that combat proteotoxic stress caused by environmental challenges. While these transcription factors are often associated with a specific stress condition, they also direct “noncanonical” transcriptional programs that serve to integrate a multitude of physiological responses required for development, metabolism, and defense responses to pathogen infections. In this review, we outline the established function of these key proteostasis transcription factors at the cell-autonomous and cell-nonautonomous level and discuss a newly emerging stress responsive transcription factor, PQM-1, within the proteostasis network. We look beyond the canonical stress response roles of proteostasis transcription factors and highlight their function in integrating different physiological stimuli to maintain cytosolic organismal proteostasis.

Suppressed anti-inflammatory heat shock response in high-risk COVID-19 patients: lessons from basic research (inclusive bats), light on conceivable therapies

The major risk factors to fatal outcome in COVID-19 patients, i.e., elderliness and pre-existing metabolic and cardiovascular diseases (CVD), share in common the characteristic of being chronic degenerative diseases of inflammatory nature associated with defective heat shock response (HSR). The molecular components of the HSR, the principal metabolic pathway leading to the physiological resolution of inflammation, is an anti-inflammatory biochemical pathway that involves molecular chaperones of the heat shock protein (HSP) family during homeostasis-threatening stressful situations (e.g., thermal, oxidative and metabolic stresses). The entry of SARS coronaviruses in target cells, on the other hand, aggravates the already-jeopardized HSR of this specific group of patients. In addition, cellular counterattack against virus involves interferon (IFN)-mediated inflammatory responses. Therefore, individuals with impaired HSR cannot resolve virus-induced inflammatory burst physiologically, being susceptible to exacerbated forms of inflammation, which leads to a fatal "cytokine storm". Interestingly, some species of bats that are natural reservoirs of zoonotic viruses, including SARS-CoV-2, possess an IFN-based antiviral inflammatory response perpetually activated but do not show any sign of disease or cytokine storm. This is possible because bats present a constitutive HSR that is by far (hundreds of times) more intense and rapid than that of human, being associated with a high core temperature. Similarly in humans, fever is a physiological inducer of HSR while antipyretics, which block the initial phase of inflammation, impair the resolution phase of inflammation through the HSR. These findings offer a rationale for the reevaluation of patient care and fever reduction in SARS, including COVID-19.

Beyond Heat Stress: Intestinal Integrity Disruption and Mechanism-Based Intervention Strategies

The current climate changes have increased the prevalence and intensity of heat stress (HS) conditions. One of the initial consequences of HS is the impairment of the intestinal epithelial barrier integrity due to hyperthermia and hypoxia following blood repartition, which often results in a leaky gut followed by penetration and transfer of luminal antigens, endotoxins, and pathogenic bacteria. Under extreme conditions, HS may culminate in the onset of “heat stroke”, a potential lethal condition if remaining untreated. HS-induced alterations of the gastrointestinal epithelium, which is associated with a leaky gut, are due to cellular oxidative stress, disruption of intestinal integrity, and increased production of pro-inflammatory cytokines. This review summarizes the possible resilience mechanisms based on in vitro and in vivo data and the potential interventions with a group of nutritional supplements, which may increase the resilience to HS-induced intestinal integrity disruption and maintain intestinal homeostasis.

Immunogenic potential of human bone marrow mesenchymal stromal cells is enhanced by hyperthermia

BACKGROUND AIMS

Bone marrow-derived mesenchymal stromal cells (MSCs) have been reported to suppress T-cell proliferation and used to alleviate the symptoms of graft-versus-host disease (GVHD). MSCs are a mixed cell population and at this time there are no tools to isolate the cells responsible for the T-cell suppression. We wanted to find a way to enhance the immune-modulatory actions of MSCs and tried varying the temperature at which they were cultured.

METHODS

We cultured human MSCs derived from healthy volunteers at different temperatures and tested their ability to switch macrophage character from pro-inflammatory to anti-inflammatory (M1 type to M2 type). Using an enzyme-linked immunosorbent assay (ELISA), we showed that when MSCs are cultured at higher temperatures their ability to induce co-cultured macrophages to produce more interleukin-10, (IL-10) (an anti-inflammatory cytokine) and less tumor necrosis factor alpha, (TNFα) (a pro-inflammatory cytokine) is increased. We performed Western blots and immunocytochemistry to screen for changes that might underlie this effect.

RESULTS

We found that in hyperthermia the heat shock protein, HSF1, translocated into the nucleus of MSCs. It appears to induce the COX2/PGE2 (Cyclooxygenase2/Prostaglandin E2) pathway described earlier as a major mechanism of MSC-directed immune-suppression.

CONCLUSION

Hyperthermia increases the efficacy of MSC-driven immune-suppression. We propose that changing the time of MSC administration to patients to mid-to-late afternoon when the body temperature is naturally highest might be beneficial. Warming the patient could also be considered.

Cationic graphene oxide nanoplatform mediates miR-101 delivery to promote apoptosis by regulating autophagy and stress

Introduction

MicroRNA-101 (miR-101) is an intense cancer suppressor with special algorithm to target a wide range of pathways and genes which indicates the ability to regulate apoptosis, cellular stress, metastasis, autophagy, and tumor growth. Silencing of some genes such as Stathmin1 with miR-101 can be interpreted as apoptotic accelerator and autophagy suppressor. It is hypothesized that hybrid microRNA (miRNA) delivery structures based on cationized graphene oxide (GO) could take superiority of targeting and photothermal therapy to suppress the cancer cells.

Materials and methods

In this study, GO nanoplatforms were covalently decorated with polyethylene glycol (PEG) and poly-l-arginine (P-l-Arg) that reduced the surface of GO and increased the near infrared absorption ~7.5-fold higher than nonreduced GO.

Results

The prepared nanoplatform [GO-PEG-(P-l-Arg)] showed higher miRNA payload and greater internalization and facilitated endosomal scape into the cytoplasm in comparison with GO-PEG. Furthermore, applying P-l-Arg, as a targeting agent, greatly improved the selective transfection of nanoplatform in cancer cells (MCF7, MDA-MB-231) in comparison with immortalized breast cells and fibroblast primary cells. Treating cancer cells with GO-PEG-(P-l-Arg)/miR-101 and incorporating near infrared laser irradiation induced 68% apoptosis and suppressed Stathmin1 protein.

Conclusion

The obtained results indicated that GO-PEG-(P-l-Arg) would be a suitable targeted delivery system of miR-101 transfection that could downregulate autophagy and conduct thermal stress to activate apoptotic cascades when combined with photothermal therapy.

Cyclooxygenase-1 and -2 modulate sweating but not cutaneous vasodilation during exercise in the heat in young men

We recently reported that the nonselective cyclooxygenase (COX) inhibitor ketorolac attenuated sweating but not cutaneous vasodilation during moderate-intensity exercise in the heat. However, the specific contributions of COX-1 and COX-2 to the sweating response remained to be determined. We tested the hypothesis that COX-1 but not COX-2 contributes to sweating with no role for either COX isoform in cutaneous vasodilation during moderate-intensity exercise in the heat. In thirteen young males (22 ± 2 years), sweat rate and cutaneous vascular conductance were measured at three forearm skin sites that were continuously treated with (1) lactated Ringer's solution (Control), (2) 150 μmmol·L-1 celecoxib, a selective COX-2 inhibitor, or (3) 10 mmol L-1 ketorolac, a nonselective COX inhibitor. Participants first rested in a non heat stress condition (≥85 min, 25°C) followed by a further 70-min rest period in the heat (35°C). They then performed 50 min of moderate-intensity cycling (~55% peak oxygen uptake) followed by a 30-min recovery period. At the end of exercise, sweat rate was lower at the 150 μmol·L-1 celecoxib (1.51 ± 0.25 mg·min-1 ·cm-2 ) and 10 mmol·L-1 ketorolac (1.30 ± 0.30 mg·min-1 ·cm-2 ) treated skin sites relative to the Control site (1.89 ± 0.27 mg·min-1 ·cm-2 ) (both P ≤ 0.05). Additionally, sweat rate at the ketorolac site was attenuated relative to the celecoxib site (P ≤ 0.05). Neither celecoxib nor ketorolac influenced cutaneous vascular conductance throughout the experiment (both P > 0.05). We showed that both COX-1 and COX-2 contribute to sweating but not cutaneous vasodilation during moderate-intensity exercise in the heat in young men.

Roles of heat shock factor 1 beyond the heat shock response

Various stress factors leading to protein damage induce the activation of an evolutionarily conserved cell protective mechanism, the heat shock response (HSR), to maintain protein homeostasis in virtually all eukaryotic cells. Heat shock factor 1 (HSF1) plays a central role in the HSR. HSF1 was initially known as a transcription factor that upregulates genes encoding heat shock proteins (HSPs), also called molecular chaperones, which assist in refolding or degrading injured intracellular proteins. However, recent accumulating evidence indicates multiple additional functions for HSF1 beyond the activation of HSPs. Here, we present a nearly comprehensive list of non-HSP-related target genes of HSF1 identified so far. Through controlling these targets, HSF1 acts in diverse stress-induced cellular processes and molecular mechanisms, including the endoplasmic reticulum unfolded protein response and ubiquitin-proteasome system, multidrug resistance, autophagy, apoptosis, immune response, cell growth arrest, differentiation underlying developmental diapause, chromatin remodelling, cancer development, and ageing. Hence, HSF1 emerges as a major orchestrator of cellular stress response pathways.

Heat stress affects prostaglandin synthesis in bovine endometrial cells

Heat stress (HS) negatively affects reproduction in cattle; however, its effect on endocrine function in bovine endometrial cells remains unclear. In this study, we examined the effects of HS on the production of prostaglandin (PG) E2 and PGF2α in the cultured bovine endometrial epithelial and stromal cells separately. To evaluate the effect of HS on endocrine function, the cells were cultured at 38.5°C (control) or 40.5°C (HS). After treatment, PGE2 and PGF2α levels were measured via enzyme immunoassay (EIA) and mRNA expressions of enzymes involved in PG synthesis were examined via quantitative reverse transcription polymerase chain reaction (RT-PCR). HS did not influence the production of PGE2 or PGF2α in the epithelial cells; however, HS significantly enhanced the production of both PGE2 and PGF2α in the stromal cells (P < 0.05). In addition, HS significantly increased phospholipase A2 (PLA2), cyclooxygenase 2 (COX2), prostaglandin F synthase (PGFS), prostaglandin E synthase (PGES), and carbonyl reductase 1 (CBR1) mRNA expression in the stromal cells (P < 0.05). The overall results suggest that HS induces mRNA expression of enzymes involved in PG synthesis, resulting in the upregulation of PGE2 and PGF2α production in the stromal cells, but not in the epithelial cells. The HS-induced increase of PGE2 and PGF2α secretion in bovine endometrial stromal cells may disrupt the normal estrous cycle and cause infertility in cows during summer.

Thermo-dependence of noxious mechanical heterotopic stimulation-dependent modulation of the spinal dorsal horn response to somatosensory stimulation

Despite the frequent clinical hyper- or hypothermia cases, thermal-dependence of the endogenous pain modulation system at the spinal cord is not well understood. We evaluate spinal dorsal horn neuronal network responses during mechanical heterotopic noxious stimuli (HNS) at three different body temperatures (34; 37 or 40°C) by measuring lumbar cord dorsum potentials activated by electrical stimulation of the ipsilateral sural nerve in adult thiopental anesthetized rats. A noxious clamp was applied randomly to the tail, right hindpaw, right forepaw, muzzle and left forepaw. HNS induced a decrease of the N wave amplitude and duration at 37°C. This effect was reduced at 40°C for both amplitude (-18.2% for 37-40°C; P<0.0005) and duration (-16.4% for 37-40°C; P<0.0001). P wave did not show neither amplitude nor duration changes at neither 3 tested temperatures. Clinical range changes of temperature could modify pain sensation, moreover, hyperthermia increases nociceptive sensory input to dorsal horn, and could exacerbate pain sensation in individuals with fever.

Nitric oxide-heat shock protein axis in menopausal hot flushes: neglected metabolic issues of chronic inflammatory diseases associated with deranged heat shock response

BACKGROUND

Although some unequivocal underlying mechanisms of menopausal hot flushes have been demonstrated in animal models, the paucity of similar approaches in humans impedes further mechanistic outcomes. Human studies might show some as yet unexpected physiological mechanisms of metabolic adaptation that permeate the phase of decreased oestrogen levels in both symptomatic and asymptomatic women. This is particularly relevant because both the severity and time span of hot flushes are associated with increased risk of chronic inflammatory disease. On the other hand, oestrogen induces the expression of heat shock proteins of the 70 kDa family (HSP70), which are anti-inflammatory and cytoprotective protein chaperones, whose expression is modulated by different types of physiologically stressful situations, including heat stress and exercise. Therefore, lower HSP70 expression secondary to oestrogen deficiency increases cardiovascular risk and predisposes the patient to senescence-associated secretory phenotype (SASP) that culminates in chronic inflammatory diseases, such as obesities, type 2 diabetes, neuromuscular and neurodegenerative diseases.

OBJECTIVE AND RATIONALE

This review focuses on HSP70 and its accompanying heat shock response (HSR), which is an anti-inflammatory and antisenescent pathway whose intracellular triggering is also oestrogen-dependent via nitric oxide (NO) production. The main goal of the manuscript was to show that the vasomotor symptoms that accompany hot flushes may be a disguised clue for important neuroendocrine alterations linking oestrogen deficiency to the anti-inflammatory HSR.

SEARCH METHODS

Results from our own group and recent evidence on hypothalamic control of central temperature guided a search on PubMed and Google Scholar websites.

OUTCOMES

Oestrogen elicits rapid production of the vasodilatory gas NO, a powerful activator of HSP70 expression. Whence, part of the protective effects of oestrogen over cardiovascular and neuroendocrine systems is tied to its capacity of inducing the NO-elicited HSR. The hypothalamic areas involved in thermoregulation (infundibular nucleus in humans and arcuate nucleus in other mammals) and whose neurons are known to have their function altered after long-term oestrogen ablation, particularly kisspeptin-neurokinin B-dynorphin neurons, (KNDy) are the same that drive neuroprotective expression of HSP70 and, in many cases, this response is via NO even in the absence of oestrogen. From thence, it is not illogical that hot flushes might be related to an evolutionary adaptation to re-equip the NO-HSP70 axis during the downfall of circulating oestrogen.

WIDER IMPLICATIONS

Understanding of HSR could shed light on yet uncovered mechanisms of menopause-associated diseases as well as on possible manipulation of HSR in menopausal women through physiological, pharmacological, nutraceutical and prebiotic interventions. Moreover, decreased HSR indices (that can be clinically determined with ease) in perimenopause could be of prognostic value in predicting the moment and appropriateness of starting a HRT.

Pharmacological and genetic inhibition of downstream targets of p38 MAPK in experimental nephrotic syndrome

Nie X, Chanley MA, Pengal R, Thomas DB, Agrawal S, Smoyer WE. Pharmacological and genetic inhibition of downstream targets of p38 MAPK in experimental nephrotic syndrome. Am J Physiol Renal Physiol 314: F602-F613, 2018. First published November 29, 2017; doi: 10.1152/ajprenal.00207.2017 .-The p38 MAPK pathway plays a crucial role in various glomerulopathies, with activation being associated with disease and inhibition being associated with disease amelioration. We hypothesized that the downstream targets of p38 MAPK, MAPK-activated protein kinase 2 and/or 3 (MK2 and/or MK3), play an important role in mediating injury in experimental nephrotic syndrome via their actions on their downstream substrates heat shock protein B1 (HSPB1) and cyclooxygenase-2 (COX-2). To test this hypothesis, the effects of both pharmacological and genetic inhibition of MK2 and MK3 were examined in mouse adriamycin (ADR) and rat puromycin aminonucleoside (PAN) nephropathy models. MK2^-/-, MK3^-/-, and MK2^-/-MK3^-/- mice were generated in the Sv129 background and subjected to ADR-induced nephropathy. MK2 and MK3 protein expression was completely abrogated in the respective knockout genotypes, and massive proteinuria and renal histopathological changes developed after ADR treatment. Furthermore, renal cortical HSPB1 was induced in all four genotypes by day 21, but HSPB1 was activated only in the wild-type and MK3^-/- mice. Expression of the stress proteins HSPB8 and glucose-regulated protein 78 (GRP78) remained unaltered across all genotypes. Finally, while MK2 and/or MK3-knockout downregulated the proinflammatory enzyme COX-2, ADR significantly induced renal cortical COX-2 only in MK2^-/- mice. Additionally, pharmacological MK2 inhibition with PF-318 during PAN-induced nephropathy did not result in significant proteinuria reduction in rats. Together, these data suggest that while the inhibition of MK2 and/or MK3 regulates the renal stress response, our currently available approaches are not yet able to safely and effectively reduce proteinuria in experimental nephrotic syndrome and that other p38MAPK downstream targets should also be considered to improve the future treatment of glomerular disease.

α-Lipoic acid prevents the intestinal epithelial monolayer damage under heat stress conditions: model experiments in Caco-2 cells

Purpose

Under conditions of high ambient temperatures and/or strenuous exercise, humans and animals experience considerable heat stress (HS) leading among others to intestinal epithelial damage through induction of cellular oxidative stress. The aim of this study was to characterize the effects of α-Lipoic Acid (ALA) on HS-induced intestinal epithelial injury using an in vitro Caco-2 cell model.

Methods

A confluent monolayer of Caco-2 cells was pre-incubated with ALA (24 h) prior to control (37 °C) or HS conditions (42 °C) for 6 or 24 h and the expression of heat shock protein 70 (HSP70), heat shock factor-1 (HSF1), and the antioxidant Nrf2 were investigated. Intestinal integrity was determined by measuring transepithelial resistance, paracellular permeability, junctional complex reassembly, and E-cadherin expression and localization. Furthermore, cell proliferation was measured in an epithelial wound healing assay and the expression of the inflammatory markers cyclooxygenase-2 (COX-2) and transforming growth Factor-β (TGF-β) was evaluated.

Results

ALA pretreatment increased the HSP70 mRNA and protein expression under HS conditions, but did not significantly modulate the HS-induced activation of HSF1. The HS-induced increase in Nrf2 gene expression as well as the Nrf2 nuclear translocation was impeded by ALA. Moreover, ALA prevented the HS-induced impairment of intestinal integrity. Cell proliferation under HS conditions was improved by ALA supplementation as demonstrated in an epithelial wound healing assay and ALA was able to affect the HS-induced inflammatory response by decreasing the COX-2 and TGF-β mRNA expression.

Conclusions

ALA supplementation could prevent the disruption of intestinal epithelial integrity by enhancing epithelial cell proliferation, and reducing the inflammatory response under HS conditions in an in vitro Caco-2 cell model.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-017-1442-y) contains supplementary material, which is available to authorized users.

Comparison of viability and antioxidant capacity between canine adipose-derived mesenchymal stem cells and heme oxygenase-1-overexpressed cells after freeze-thawing

Allogenic adipose-derived mesenchymal stem cells (Ad-MSCs) are an alternative source for cytotherapy owing to their antioxidant and anti-inflammatory effects. Frozen-thawed allogenic Ad-MSCs can be used instantly for this purpose. However, the viability and function of frozen-thawed Ad-MSCs have not been clearly evaluated. The purpose of this study was to compare the viability and function of Ad-MSCs and heme oxygenase-1 (HO-1)-overexpressed Ad-MSCs in vitro after freeze-thawing. The viability, proliferation, antioxidant capacity and mRNA gene expression of growth factors were evaluated. Frozen-thawed cells showed significantly lower viability than fresh cells (77% for Ad-MSCs and 71% for HO-1 Ad-MSCs, P<0.01). However, the proliferation rate of frozen-thawed Ad-MSCs increased and did not differ from that of fresh Ad-MSCs after 3 days of culture. In contrast, the proliferation rate of HO-1-overexpressed Ad-MSCs was lower than that of Ad-MSCs. The mRNA expression levels of TGF-β, HGF and VEGF did not differ between fresh and frozen-thawed Ad-MSCs, but COX-2 and IL-6 had significantly higher mRNA expression in frozen cells than fresh cells (P<0.05). Fresh Ad-MSCs exhibited higher HO-1 mRNA expression than frozen-thawed Ad-MSCs, and fresh HO-1-overexpressed Ad-MSCs exhibited higher than fresh Ad-MSCs (P<0.05). However, there was no significant difference between fresh and frozen HO-1-overexpressed Ad-MSCs. The antioxidant capacity of HO-1-overexpressed Ad-MSCs was significantly higher than that of Ad-MSCs. Cryopreservation of Ad-MSCs negatively affects viability and antioxidant capacity, and HO-1-overexpressed Ad-MSCs might be useful to maximize the effect of Ad-MSCs for cytotherapy.

CFTR-regulated MAPK/NF-κB signaling in pulmonary inflammation in thermal inhalation injury

The mechanism underlying pulmonary inflammation in thermal inhalation injury remains elusive. Cystic fibrosis, also hallmarked with pulmonary inflammation, is caused by mutations in CFTR, the expression of which is temperature-sensitive. We investigated whether CFTR is involved in heat-induced pulmonary inflammation. We applied heat-treatment in 16HBE14o- cells with CFTR knockdown or overexpression and heat-inhalation in rats in vivo. Heat-treatment caused significant reduction in CFTR and, reciprocally, increase in COX-2 at early stages both in vitro and in vivo. Activation of ERK/JNK, NF-κB and COX-2/PGE2 were detected in heat-treated cells, which were mimicked by knockdown, and reversed by overexpression of CFTR or VX-809, a reported CFTR mutation corrector. JNK/ERK inhibition reversed heat-/CFTR-knockdown-induced NF-κB activation, whereas NF-κB inhibitor showed no effect on JNK/ERK. IL-8 was augmented by heat-treatment or CFTR-knockdown, which was abolished by inhibition of NF-κB, JNK/ERK or COX-2. Moreover, in vitro or in vivo treatment with curcumin, a natural phenolic compound, significantly enhanced CFTR expression and reversed the heat-induced increases in COX-2/PGE2/IL-8, neutrophil infiltration and tissue damage in the airway. These results have revealed a CFTR-regulated MAPK/NF-κB pathway leading to COX-2/PGE2/IL-8 activation in thermal inhalation injury, and demonstrated therapeutic potential of curcumin for alleviating heat-induced pulmonary inflammation.

The regulatory roles of NADPH oxidase, intra- and extra-cellular HSP70 in pancreatic islet function, dysfunction and diabetes

The 70 kDa heat-shock protein (HSP70) family is important for a dynamic range of cellular processes that include protection against cell stress, modulation of cell signalling, gene expression, protein synthesis, protein folding and inflammation. Within this family, the inducible 72 kDa and the cognate 73 kDa forms are found at the highest level. HSP70 has dual functions depending on location. For example, intracellular HSP70 (iHSP70) is anti-inflammatory whereas extracellular HSP70 (eHSP70) has a pro-inflammatory function, resulting in local and systemic inflammation. We have recently identified a divergence in the levels of eHSP70 and iHSP70 in subjects with diabetes compared with healthy subjects and also reported that eHSP70 was correlated with insulin resistance and pancreatic β-cell dysfunction/death. In the present review, we describe possible mechanisms by which HSP70 participates in cell function/dysfunction, including the activation of NADPH oxidase isoforms leading to oxidative stress, focusing on the possible role of HSPs and signalling in pancreatic islet α- and β-cell physiological function in health and Type 2 diabetes mellitus.

Fever and the thermal regulation of immunity: the immune system feels the heat

Fever is a cardinal response to infection that has been conserved in warm-blooded and cold-blooded vertebrates for more than 600 million years of evolution. The fever response is executed by integrated physiological and neuronal circuitry and confers a survival benefit during infection. In this Review, we discuss our current understanding of how the inflammatory cues delivered by the thermal element of fever stimulate innate and adaptive immune responses. We further highlight the unexpected multiplicity of roles of the pyrogenic cytokine interleukin-6 (IL-6), both during fever induction and during the mobilization of lymphocytes to the lymphoid organs that are the staging ground for immune defence. We also discuss the emerging evidence suggesting that the adrenergic signalling pathways associated with thermogenesis shape immune cell function.

Quercetin attenuates cyclooxygenase-2 expression in response to acute ureteral obstruction

Unilateral ureteral obstruction (UUO) is associated with increased hydrostatic pressure, inflammation, and oxidative stress in the renal parenchyma. Previous studies have demonstrated marked cyclooxygenase (COX)-2 induction in renal medullary interstitial cells (RMICs) in response to UUO. The aim of the present study was to evaluate the effect of quercetin, a naturally occurring antioxidant, on COX-2 induction in vivo and in vitro. Rats subjected to 24 h of UUO were treated intraperitoneally with quercetin (50 mg·kg(-1)·day(-1)). Quercetin partly prevented COX-2 induction in the renal inner medulla in response to UUO. Moreover, RMICs exposed to conditions associated with obstruction, inflammation (produced by IL-1β), oxidative stress (produced by H2O2), and mechanical stress (produced by stretch) showed increased COX-2 expression. Interestingly, quercetin reduced COX-2 induction in RMICs subjected to stretched. Similarly, PGE2 production was markedly increased in RMICs exposed to stretch and was reversed to control levels by quercetin treatment. Furthermore, stretch-induced phosphorylation of ERK1/2 was blocked by quercetin, and inhibition of ERK1/2 attenuated stretch-induced COX-2 induction in RMICs. These results indicate that quercetin attenuated the induction of COX-2 expression and activity in RMICs exposed to mechanical stress as a consequence of acute UUO and that the MAPK ERK1/2 pathway might be involved in this quercetin-mediated reduction in COX-2.

Polymorphisms in human heat shock factor-1 and analysis of potential biological consequences

The stress-activated transcription factor, heat shock factor-1 (HSF1), regulates many genes including cytoprotective heat shock proteins (HSPs). We hypothesized that polymorphisms in HSF1 may alter the level or function of HSF1 protein accounting for interindividual viability in disease susceptibility or prognosis. We searched for exomic variants in HSF1 by querying human genome databases and directly sequencing DNA from 80 anonymous genomic DNA samples. Overall, HSF1 sequence was highly conserved, with no common variations. We found 31 validated deviations from a reference sequence in the dbSNP database and an additional 5 novel variants by sequencing, with allele frequencies that were 0.06 or less. Of these 36, 2 were in 5'-untranslated region (5'UTR), 10 in 3'UTR, and 24 in the coding region. The potential effects of 5'UTR on secondary structure, protein structure/function, and 3'UTR targets of microRNAs were analyzed using RNAFold, PolyPhen-2, SIFT, and MicroSNiper. One of the 5'UTR variants was predicted to strengthen secondary structure. Eight of 3'UTR variants were predicted to modify microRNA target sequences. Eight of the coding region variants were predicted to modify HSF1 structure/function. Reducing HSF1 levels in A549 cells using short hairpin RNA (shRNA) increased sensitivity to heat-induced killing demonstrating the impact that genetic variants that reduce HSF1 levels might have. Using the pmirGLO expression system, we found that the wild-type HSF1 3'UTR suppressed translation of a firefly luciferase reporter plasmid by 65 %. Introducing two of four 3'UTR single nucleotide polymorphisms (SNPs) increased HSF1 3'UTR translational suppression by 27-44 % compared with the wild-type HSF1 3'UTR sequence while a third SNP reduced suppression by 25 %. HSF1 variants may alter HSF1 protein levels or function with potential effects on cell functions, including sensitivity to stress.

Fever, immunity, and molecular adaptations

The heat shock response (HSR) is an ancient and highly conserved process that is essential for coping with environmental stresses, including extremes of temperature. Fever is a more recently evolved response, during which organisms temporarily subject themselves to thermal stress in the face of infections. We review the phylogenetically conserved mechanisms that regulate fever and discuss the effects that febrile-range temperatures have on multiple biological processes involved in host defense and cell death and survival, including the HSR and its implications for patients with severe sepsis, trauma, and other acute systemic inflammatory states. Heat shock factor-1, a heat-induced transcriptional enhancer is not only the central regulator of the HSR but also regulates expression of pivotal cytokines and early response genes. Febrile-range temperatures exert additional immunomodulatory effects by activating mitogen-activated protein kinase cascades and accelerating apoptosis in some cell types. This results in accelerated pathogen clearance, but increased collateral tissue injury, thus the net effect of exposure to febrile range temperature depends in part on the site and nature of the pathologic process and the specific treatment provided.

The fat cell senescence hypothesis: a mechanism responsible for abrogating the resolution of inflammation in chronic disease

PURPOSE OF REVIEW

Obesity is a chronic inflammatory disease in which the physiological resolution of inflammation is attenuated, leading to low-grade inflammation throughout the body. However, the heat shock response, which is a key component of the physiological response to resolve inflammation, is seriously hampered in adipose tissue and other metabolic organs (e.g. skeletal muscle, liver, pancreatic β-cells) in metabolic diseases. In this review, we hypothesize that adipocyte metabolic stress triggers the onset of fat cell senescence, and companion senescence-associated secretory phenotype (SASP), and that such a scenario is responsible for attenuating the resolution of inflammation.

RECENT FINDINGS

We shall discuss the role of the heat shock response in the context of the resolution of inflammation and the relevance of heat shock response blockade in chronic inflammatory diseases. Sirtuin-1 is responsible for the induction of heat shock transcription factor-1 mRNA expression and for the stabilization of heat shock transcription factor-1 in a high-profile activity state. However, adipose tissue-emanated SASP depress sirtuin-1 expression, leading adipocytes to a perpetual state of unresolved inflammation, due to a dampening of the heat shock response.

SUMMARY

The advance of inflammasome-mediated SASP from adipose to other tissues promotes cellular senescence in many other cells of the organism, aggravating obesity-dependent chronic inflammation. Inducers of heat shock response (e.g. heat shock itself, physical exercise and calorie restriction) may efficiently interrupt this vicious cycle and are envisaged as the best and also the most economical treatment for obesity-related chronic diseases.

Albumin-induced podocyte injury and protection are associated with regulation of COX-2

Albuminuria is both a hallmark and a risk factor for progressive glomerular disease, and results in increased exposure of podocytes to serum albumin with its associated factors. Here in vivo and in vitro models of serum albumin overload were used to test the hypothesis that albumin-induced proteinuria and podocyte injury directly correlate with COX-2 induction. Albumin induced COX-2, MCP-1, CXCL1 and the stress protein HSP25 in both rat glomeruli and cultured podocytes, while B7-1 and HSP70i were also induced in podocytes. Podocyte exposure to albumin induced both mRNA and protein and enhanced the mRNA stability of COX-2, a key regulator of renal hemodynamics and inflammation, which renders podocytes susceptible to injury. Podocyte exposure to albumin also stimulated several kinases (p38 MAPK, MK2, JNK/SAPK and ERK1/2), inhibitors of which (except JNK/SAPK) down-regulated albumin-induced COX-2. Inhibition of AMPK, PKC and NFκB also down-regulated albumin-induced COX-2. Critically, albumin-induced COX-2 was also inhibited by glucocorticoids and thiazolidinediones, both of which directly protect podocytes against injury. Furthermore, specific albumin-associated fatty acids were identified as important contributors to COX-2 induction, podocyte injury and proteinuria. Thus, COX-2 is associated with podocyte injury during albuminuria, as well as with the known podocyte protection imparted by glucocorticoids and thiazolidinediones. Moreover, COX-2 induction, podocyte damage and albuminuria appear mediated largely by serum albumin-associated fatty acids.

HSF1 protects neurons through a novel trimerization- and HSP-independent mechanism

Heat shock factor 1 (HSF1) protects neurons from death caused by the accumulation of misfolded proteins. It is believed that this protective effect is mediated by the transcriptional stimulation of genes encoding heat shock proteins (HSPs), a family of chaperones that refold or degrade misfolded proteins. Whether HSF1 is protective when neuronal death is not caused by protein misfolding has not been studied. Here, we report that HSF1 expression is necessary for the survival of rat neurons and that HSF1 mRNA and protein expression is reduced in neurons primed to die. Knock-down of HSF1 induces death of otherwise healthy neurons, whereas reestablishment of elevated levels of HSF1 protects neurons even when death is not due to accumulation of misfolded proteins. Neuroprotection by HSF1 does not require its trimerization, an event obligatory for the binding of HSF1 to heat shock elements within HSP gene promoters. Moreover, knock-down of HSP70 or blockade of HSP90 signaling does not reduce neuroprotection by HSF1. Although several neuroprotective molecules and signaling pathways, including CaMK, PKA, Casein kinase-II, and the Raf-MEK-ERK and PI-3K-Akt pathways, are not required for HSF1-mediated neuroprotection, protection is abrogated by inhibition of classical histone deacetylases (HDACs). We report that the novel mechanism of neuroprotection by HSF1 involves cooperation with SIRT1, an HDAC with well documented neuroprotective effects. Using a cell culture model of Huntington's disease, we show that HSF1 trimerization is not required for protection against mutant huntingtin-induced neurotoxicity, suggesting that HSF1 can protect neurons against both proteinopathic and nonproteinopathic death through a noncanonical pathway.

The proteasome inhibitor bortezomib is a potent inducer of zinc finger AN1-type domain 2a gene expression: role of heat shock factor 1 (HSF1)-heat shock factor 2 (HSF2) heterocomplexes

The zinc finger AN1-type domain 2a gene, also known as arsenite-inducible RNA-associated protein (AIRAP), was recently identified as a novel human canonical heat shock gene strictly controlled by heat shock factor (HSF) 1. Little is known about AIRAP gene regulation in human cells. Here we report that bortezomib, a proteasome inhibitor with anticancer and antiangiogenic properties used in the clinic for treatment of multiple myeloma, is a potent inducer of AIRAP expression in human cells. Using endothelial cells as a model, we unraveled the molecular mechanism regulating AIRAP expression during proteasome inhibition. Bortezomib induces AIRAP expression at the transcriptional level early after treatment, concomitantly with polyubiquitinated protein accumulation and HSF activation. AIRAP protein is detected at high levels for at least 48 h after bortezomib exposure, together with the accumulation of HSF2, a factor implicated in differentiation and development regulation. Different from heat-mediated induction, in bortezomib-treated cells, HSF1 and HSF2 interact directly, forming HSF1-HSF2 heterotrimeric complexes recruited to a specific heat shock element in the AIRAP promoter. Interestingly, whereas HSF1 has been confirmed to be critical for AIRAP gene transcription, HSF2 was found to negatively regulate AIRAP expression after bortezomib treatment, further emphasizing an important modulatory role of this transcription factor under stress conditions. AIRAP function is still not defined. However, the fact that AIRAP is expressed abundantly in primary human cells at bortezomib concentrations comparable with plasma levels in treated patients suggests that AIRAP may participate in the regulatory network controlling proteotoxic stress during bortezomib treatment.

Transcription regulation of HYPK by Heat Shock Factor 1

HYPK (Huntingtin Yeast Partner K) was originally identified by yeast two-hybrid assay as an interactor of Huntingtin, the protein mutated in Huntington's disease. HYPK was characterized earlier as an intrinsically unstructured protein having chaperone-like activity in vitro and in vivo. HYPK has the ability of reducing rate of aggregate formation and subsequent toxicity caused by mutant Huntingtin. Further investigation revealed that HYPK is involved in diverse cellular processes and required for normal functioning of cells. In this study we observed that hyperthermia increases HYPK expression in human and mouse cells in culture. Expression of exogenous Heat Shock Factor 1 (HSF1), upon heat treatment could induce HYPK expression, whereas HSF1 knockdown reduced endogenous as well as heat-induced HYPK expression. Putative HSF1-binding site present in the promoter of human HYPK gene was identified and validated by reporter assay. Chromatin immunoprecipitation revealed in vivo interaction of HSF1 and RNA polymerase II with HYPK promoter sequence. Additionally, acetylation of histone H4, a known epigenetic marker of inducible HSF1 binding, was observed in response to heat shock in HYPK gene promoter. Overexpression of HYPK inhibited cells from lethal heat-induced death whereas knockdown of HYPK made the cells susceptible to lethal heat shock-induced death. Apart from elevated temperature, HYPK was also upregulated by hypoxia and proteasome inhibition, two other forms of cellular stress. We concluded that chaperone-like protein HYPK is induced by cellular stress and under transcriptional regulation of HSF1.

Fever, hyperthermia and the heat shock response

The heat shock response is a highly conserved primitive response that is essential for survival against a wide range of stresses, including extremes of temperature. Fever is a more recently evolved response, during which organisms raise their core body temperature and temporarily subject themselves to thermal stress in the face of infections. The present review documents studies showing the potential overlap between the febrile response and the heat shock response and how both activate the same common transcriptional programme (although with different magnitudes) including the stress-activated transcription factor, heat shock factor-1, to modify host defences in the context of infection, inflammation and injury. The review focuses primarily on how hyperthermia within the febrile range that often accompanies infections and inflammation acts as a biological response modifier and modifies innate immune responses. The characteristic 2-3 °C increase in core body temperature during fever activates and utilises elements of the heat shock response pathway to modify cytokine and chemokine gene expression, cellular signalling and immune cell mobilisation to sites of inflammation, infection and injury. Interestingly, typical proinflammatory agonists such as Toll-like receptor agonists modify the heat shock-induced transcriptional programme and expression of HSP genes following co-exposure to febrile range hyperthermia or heat shock, suggesting a complex reciprocal regulation between the inflammatory pathway and the heat shock response pathway.