Inhibition of HSP90α protects cultured neurons from oxygen-glucose deprivation induced necroptosis by decreasing RIP3 expression

Heat shock protein 90α (HSP90α) maintains cell stabilization and regulates cell death, respectively. Recent studies have shown that HSP90α is involved in receptor interacting protein 3 (RIP3)-mediated necroptosis in HT29 cells. It is known that oxygen and glucose deprivation (OGD) can induce necroptosis, which is regulated by RIP3 in neurons. However, it is still unclear whether HSP90α participates in the process of OGD-induced necroptosis in cultured neurons via the regulation of RIP3. Our study found that necroptosis occurs in primary cultured cortical neurons and PC-12 cells following exposure to OGD insult. Additionally, the expression of RIP3/p-RIP3, MLKL/p-MLKL, and the RIP1/RIP3 complex (necrosome) significantly increased following OGD, as measured through immunofluorescence (IF) staining, Western blotting (WB), and immunoprecipitation (IP) assay. Additionally, data from computer simulations and IP assays showed that HSP90α interacts with RIP3. In addition, HSP90α was overexpressed following OGD in cultured neurons, as measured through WB and IF staining. Inhibition of HSP90α in cultured neurons, using the specific inhibitor, geldanamycin (GA), and siRNA/shRNA of HSP90α, protected cultured neurons from necrosis. Our study showed that the inhibitor of HSP90α, GA, rescued cultured neurons not only by decreasing the expression of total RIP3/MLKL, but also by decreasing the expression of p-RIP3/p-MLKL and the RIP1/RIP3 necrosome. In this study, we reveal that inhibition of HSP90α protects primary cultured cortical neurons and PC-12 cells from OGD-induced necroptosis through the modulation of RIP3 expression.

A secreted Heat shock protein 90 of Trichomonas vaginalis

Trichomonas vaginalis is a causative agent of Trichomoniasis, a leading non-viral sexually transmitted disease worldwide. In the current study, we show Heat shock protein 90 is essential for its growth. Upon genomic analysis of the parasite, it was found to possess seven ORFs which could potentially encode Hsp90 isoforms. We identified a cytosolic Hsp90 homolog, four homologs which can align to truncated cytosolic Hsp90 gene products along with two Grp94 homologs (ER isoform of Hsp90). However, both Grp94 orthologs lacked an ER retention motif. In cancer cells, it is very well established that Hsp90 is secreted and regulates key clients involved in metastases, migration, and invasion. Since Trichomonas Grp94 lacks ER retention motif, we examined the possibility of its secretion. By using cell biology and biochemical approaches we show that the Grp94 isoform of Hsp90 is secreted by the parasite by the classical ER-Golgi pathway. This is the first report of a genome encoded secreted Hsp90 in a clinically important parasitic protozoan.

Hsp90 is an essential chaperone in eukaryotes and it is often described as a master regulator of cellular homeostasis. In addition to its well-known functions inside the cell, extracellular Hsp90 has also been implicated in migration and invasion of tumor cells. We have, for the first time, identified the presence of an extracellular Hsp90 in a parasitic protozoan, Trichomonas vaginalis. The extracellular Hsp90 is a Grp94 homolog that lacks a canonical ER retention signal. Our analysis of Grp94 sequences from protozoa shows that it is uncommon for a Grp94 to lack ER retention signal. In the current study, we characterized the biochemical parameters and established the extracellular localization of this Hsp90 paralog. This secreted Hsp90 in Trichomonas can potentially modulate host-pathogen interaction.

Bisphenol A (BPA) modulates the expression of endocrine and stress response genes in the freshwater snail Physa acuta

Bisphenol A (BPA), a known endocrine disrupting chemical (EDC) that can mimic the action of oestrogens by interacting with hormone receptors, is potentially able to influence reproductive functions in vertebrates and invertebrates. The freshwater pulmonate Physa acuta is a sensitive organism to xenobiotics appropriate for aquatic toxicity testing in environmental studies. This study was conducted to explore the effects of BPA on the Gastropoda endocrine system. The effects following a range of exposure times (5-96h) to BPA in P. acuta were evaluated at the molecular level by analysing changes in the transcriptional activity of the endocrine-related genes oestrogen receptor (ER), oestrogen-related receptor (ERR), and retinoid X receptor (RXR), as well as in genes involved in the stress response, such as hsp70 and hsp90. Real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis showed that BPA induced a significant increase in the mRNA levels of ER, ERR, and RXR, suggesting that these receptors could be involved in similar pathways or regulation events in the endocrine disruptor activity of this chemical at the molecular level in Gastropoda. Additionally, the hsp70 expression was upregulated after 5 and 72h of BPA exposures, but hsp90 was only upregulated after 5h of BPA exposure. Finally, we assessed the glutathione-S-transferase (GST) activity after BPA treatment and found that it was affected after 48h. In conclusion, these data provide, for the first time, evidences of molecular effects produced by BPA in the endocrine system of Gastropoda, supporting the potential of ER, ERR and RXR as biomarkers to analyse putative EDCs in ecotoxicological studies. Moreover, our results suggest that P. acuta is an appropriate sentinel organism to evaluate the effect of EDCs in the freshwater environment.

The Molecular Chaperone HSP90 Promotes Notch Signaling in the Germline of Caenorhabditis elegans

In a genetic screen to identify genes that promote GLP-1/Notch signaling in Caenorhabditis elegans germline stem cells, we found a single mutation, om40, defining a gene called ego-3. ego-3(om40) causes several defects in the soma and the germline, including paralysis during larval development, sterility, delayed proliferation of germline stem cells, and ectopic germline stem cell proliferation. Whole genome sequencing identified om40 as an allele of hsp-90, previously known as daf-21, which encodes the C. elegans ortholog of the cytosolic form of HSP90. This protein is a molecular chaperone with a central position in the protein homeostasis network, which is responsible for proper folding, structural maintenance, and degradation of proteins. In addition to its essential role in cellular function, HSP90 plays an important role in stem cell maintenance and renewal. Complementation analysis using a deletion allele of hsp-90 confirmed that ego-3 is the same gene. hsp-90(om40) is an I→N conservative missense mutation of a highly conserved residue in the middle domain of HSP-90 RNA interference-mediated knockdown of hsp-90 expression partially phenocopied hsp-90(om40), confirming the loss-of-function nature of hsp-90(om40) Furthermore, reduced HSP-90 activity enhanced the effect of reduced function of both the GLP-1 receptor and the downstream LAG-1 transcription factor. Taken together, our results provide the first experimental evidence of an essential role for HSP90 in Notch signaling in development.

Comparisons of Expression Levels of Heat Shock Proteins (hsp70 and hsp90) From Anaphothrips obscurus (Thysanoptera: Thripidae) in Polymorphic Adults Exposed to Different Heat Shock Treatments

Heat shock proteins (Hsps) are prominent proteins that greatly contribute to insect survival under stress conditions. In this study, we cloned two Hsp transcripts (Aohsp70 and Aohsp90) from the grass thrip, Anaphothrips obscurus (Müller) (Thysanoptera: Thripidae), which is a polymorphic winged pest of corn and wheat. The cDNA sequences of Aohsp70 and Aohsp90 are 2382 and 2504 bp long, and encode proteins with calculated molecular weights of 70.02 kDa and 83.40 kDa, respectively. Aohsp90 was highly expressed in adults of both brachypters and macropters. Aohsp70 had different expression patterns in brachypters and macropters and was also highly expressed in the pupae of macropters. After adults were exposed to an ascending series of heat shocks, the expression of both Aohsp70 and Aohsp90 were up-regulated. In macropters and brachypters, the maximum induced levels of Aohsp70 (approximately 90-fold and 280-fold, respectively) were higher than Aohsp90 (approximately 2.4-fold and 1.8-fold, respectively). In addition, the up-regulation of Aohsp70 was significantly higher in brachypters than in macropters. Brachypters had a significantly higher Ltem50 (43.2°C) than macropters (42.5°C), which implied that brachypters are more tolerant to thermal stress than macropters. This study has shown that the expression patterns of Aohsp70 and Aohsp90 are variable among different life stages and thermal stress induced different levels of expressions in macropterous and brachypterous adults.

A field and laboratory study of the responses of cytoprotection and osmoregulation to salinity stress in mosquitofish (Gambusia affinis)

The mosquitofish (Gambusia affinis) naturally inhabits freshwater (FW; 1-3‰) and seawater (SW; 28-33‰) ponds in constructed wetland. To explore the physiological status and molecular mechanisms for salinity adaptation of the mosquitofish, cytoprotective responses and osmoregulation were examined. In the field study, activation of protein quality control (PQC) mechanism through upregulation of the abundance of heat shock protein (HSP) 90 and 70 and ubiquitin-conjugated proteins was found in the mosquitofish gills from SW pond compared to the individuals of FW pond. The levels of aggregated proteins in mosquitofish gills had no significant difference between FW and SW ponds. Furthermore, the osmoregulatory responses revealed that the body fluid osmolality and muscle water contents of the mosquitofish from two ponds were maintained within a physiological range while branchial Na⁺/K⁺-ATPase (NKA) expression was higher in the individuals from SW than FW ponds. Subsequently, to further clarify whether the cellular stress responses and osmoregulation were mainly induced by hypertonicity, a laboratory salinity acclimation experiment was conducted. The results from the laboratory experiment were similar to the field study. Branchial PQC as well as NKA responses were induced by SW acclimation compared to FW-acclimated individuals. Taken together, induction of gill PQC and NKA responses implied that SW represents an osmotic stress for mosquitofish. Activation of PQC was suggested to provide an osmoprotection to prevent the accumulation of aggregated proteins. Moreover, an increase in branchial NKA responses for osmoregulatory adjustment was required for the physiological homeostasis of body fluid osmolality and muscle water content.

Zebrafish Embryonic Slow Muscle Is a Rapid System for Genetic Analysis of Sarcomere Organization by CRISPR/Cas9, but Not NgAgo

Zebrafish embryonic slow muscle cells, with their superficial localization and clear sarcomere organization, provide a useful model system for genetic analysis of muscle cell differentiation and sarcomere assembly. To develop a quick assay for testing CRISPR-mediated gene editing in slow muscles of zebrafish embryos, we targeted a red fluorescence protein (RFP) reporter gene specifically expressed in slow muscles of myomesin-3-RFP (Myom3-RFP) zebrafish embryos. We demonstrated that microinjection of RFP-sgRNA with Cas9 protein or Cas9 mRNA resulted in a mosaic pattern in loss of RFP expression in slow muscle fibers of the injected zebrafish embryos. To uncover gene functions in sarcomere organization, we targeted two endogenous genes, slow myosin heavy chain-1 (smyhc1) and heat shock protein 90 α1 (hsp90α1), which are specifically expressed in zebrafish muscle cells. We demonstrated that injection of Cas9 protein or mRNA with respective sgRNAs targeted to smyhc1 or hsp90a1 resulted in a mosaic pattern of myosin thick filament disruption in slow myofibers of the injected zebrafish embryos. Moreover, Myom3-RFP expression and M-line localization were also abolished in these defective myofibers. Given that zebrafish embryonic slow muscles are a rapid in vivo system for testing genome editing and uncovering gene functions in muscle cell differentiation, we investigated whether microinjection of Natronobacterium gregoryi Argonaute (NgAgo) system could induce genetic mutations and muscle defects in zebrafish embryos. Single-strand guide DNAs targeted to RFP, Smyhc1, or Hsp90α1 were injected with NgAgo mRNA into Myom3-RFP zebrafish embryos. Myom3-RFP expression was analyzed in the injected embryos. The results showed that, in contrast to the CRISPR/Cas9 system, injection of the NgAgo-gDNA system did not affect Myom3-RFP expression and sarcomere organization in myofibers of the injected embryos. Sequence analysis failed to detect genetic mutations at the target genes. Together, our studies demonstrate that zebrafish embryonic slow muscle is a rapid model for testing gene editing technologies in vivo and uncovering gene functions in muscle cell differentiation.

Molecular characterization of three Hsp90 from Pieris and expression patterns in response to cold and thermal stress in summer and winter diapause of Pieris melete

Heat shock proteins (Hsps) have been linked to stresses and winter diapause in insects, but whether they are components of summer diapause is still unknown. In this study, complementary DNAs of Hsp90 from Pieris melete, Pieris rapae and Pieris canidia named PmHsp90, PrHsp90 and PcHsp90, respectively, were cloned and sequenced. The deduced amino acid sequence consisted of 718 amino acid residues with a putative molecular mass of 82.6, 82.6 and 82.7 kDa, respectively. The amino acid sequences contained all of the five conserved signature motifs in the Hsp90 family and a bHLH protein folding activity region. The differential expression pattern of PmHsp90 in response to summer diapause and winter diapause, which are related to heat/cold stress, was investigated. Cold stress induced Hsp90 up-regulation in summer and winter diapause pupae, but not in non-diapause individuals. Heat shock up-regulated PmHsp90 gradually with an increase in temperature in summer diapause, and PmHsp90 was rapidly up-regulated in winter diapause. After 30 min heat shock at 39°C, substantial up-regulation of PmHsp90 transcript levels were observed both in summer and winter diapause. However, in non-diapause a relatively stable expression was found under different durations of 39°C heat shock. Compared to the optimal treatment of 18°C for diapause development, a high temperature acclimation of 31°C induced PmHsp90 up-regulation in summer diapause, whereas a low temperature acclimation of 4°C induced up-regulation in winter diapause. The current results indicate that Hsp90 may play an important role in response to heat/cold stress both in summer and winter diapause.

HSP60 and HSP90β from blunt snout bream, Megalobrama amblycephala: Molecular cloning, characterization, and comparative response to intermittent thermal stress and Aeromonas hydrophila infection

Heat shock proteins (HSPs) play critical roles in the process of anti-stress and immunity and are implicated in autoimmune diseases. In order to understand the comparative stress responses of HSP60 and HSP90β under intermittent thermal stress and Aeromonas hydrophila infection, we cloned their full-length cDNAs from Megalobrama amblycephala liver, predicted their secondary and tertiary structure, and examined their tissue-specific expression patterns. The full length of HSP60 and HSP90β cDNAs indicated that they included all signature sequences of corresponding protein families. They showed high homology to their counterparts in other species, and were consistent with the known classification of fishes based on phylogenetic analysis. HSP60 showed the highest expression in head-kidney, brain, and gill, while HSP90β presented higher in hindgut, liver, and brain. Significant mRNA expression differences were determined between HSP60 and HSP90β in tissues of bladder, liver, heart, and gill. During thermal stress and recovery phase, the highest expression of them were observed at the first recovery for 2 d and 1 d, respectively. The expression between them were extremely significant difference during the first recovery and second stress period. After A. hydrophila infection, their expressions were extremely significantly upregulated. The significant upregulation and rapid response indicated that they were sensitive to thermal stress and bacterial challenge. This study demonstrated that HSP60 and HSP90β might participate in innate immune and environmental responses of M. amblycephala. It indicated that they could be used as biomarkers to test the stress caused by local aquaculture environment.

Heat Shock Factor HsfA1a Is Essential for R Gene-Mediated Nematode Resistance and Triggers H2O2 Production1

Plants generate reactive oxygen species (ROS) in the apoplast in response to pathogen attack, especially following resistance (R) gene-mediated pathogen recognition; however, the mechanisms activating ROS generation remain unknown. Here, we demonstrate that RKN (Meloidogyne incognita) infection rapidly induces ROS accumulation in the roots of tomato (Solanum lycopersicum) plants that contain the R gene Mi-1.2 but rarely induces ROS accumulation in the susceptible or Mi-1.2-silenced resistant genotypes. RNK also induces the hypersensitive response, a form of programmed cell death, in Mi-1.2 plants. RKN induces the expression of numerous class-A heat shock factor (HsfA) genes in resistant tomato plants. Silencing HsfA1a compromises Mi-1.2-mediated resistance, apoplastic H₂O₂ accumulation, and the transcription of whitefly induced 1 (Wfi1), which encodes a respiratory burst oxidase homolog. HsfA1a regulates Wfi1 transcription by binding to the Wfi1 promoter, and silencing of Wfi1 compromises Mi-1.2-mediated resistance. HsfA1a and Wfi1 are involved in Mi-1.2-triggered Hsp90 accumulation and basal defense in susceptible tomato. Thus, HsfA-1aWfi1-dependent ROS signaling functions as a crucial regulator of plant defense responses.

MIR21 Drives Resistance to Heat Shock Protein 90 Inhibition in Cholangiocarcinoma

BACKGROUND & AIMS

Cholangiocarcinomas (CCA) are resistant to chemotherapy, so new therapeutic agents are needed. We performed a screen to identify small-molecule compounds that are active against CCAs. Levels of microRNA 21 (MIR21 or miRNA21) are increased in CCAs. We investigated whether miRNA21 mediates resistance of CCA cells and organoids to HSP90 inhibitors.

METHODS

We performed a high-throughput screen of 484 small-molecule compounds to identify those that reduced viability of 6 human CCA cell lines. We tested the effects of HSP90 inhibitors on cells with disruption of the MIR21 gene, cells incubated with MIR21 inhibitors, and stable cell lines with inducible expression of MIR21. We obtained CCA biopsies from patients, cultured them as organoids (patient-derived organoids). We assessed their architecture, mutation and gene expression patterns, response to compounds in culture, and when grown as subcutaneous xenograft tumors in mice.

RESULTS

Cells with IDH1 and PBRM1 mutations had the highest level of sensitivity to histone deacetylase inhibitors. HSP90 inhibitors were effective in all cell lines, irrespective of mutations. Sensitivity of cells to HSP90 inhibitors correlated inversely with baseline level of MIR21. Disruption of MIR21 increased cell sensitivity to HSP90 inhibitors. CCA cells that expressed transgenic MIR21 were more resistant to HSP90 inhibitors than cells transfected with control vectors; inactivation of MIR21 in these cells restored sensitivity to these agents. MIR21 was shown to target the DnaJ heat shock protein family (Hsp40) member B5 (DNAJB5). Transgenic expression of DNAJB5 in CCA cells that overexpressed MIR21 re-sensitized them to HSP90 inhibitors. Sensitivity of patient-derived organoids to HSP90 inhibitors, in culture and when grown as xenograft tumors in mice, depended on expression of miRNA21.

CONCLUSIONS

miRNA21 appears to mediate resistance of CCA cells to HSP90 inhibitors by reducing levels of DNAJB5. HSP90 inhibitors might be developed for the treatment of CCA and miRNA21 might be a marker of sensitivity to these agents.

Synthesis and Evaluation of the Tumor Cell Growth Inhibitory Potential of New Putative HSP90 Inhibitors

Background: Heat shock protein 90 (HSP90) is a well-known target for cancer therapy. In a previous work, some of us have reported a series of 3-aryl-naphtho[2,3-d]isoxazole-4,9-diones as inhibitors of HSP90. Methods: In the present work, various compounds with new chromenopyridinone and thiochromenopyridinone scaffolds were synthesized as potential HSP90 inhibitors. Their binding affinity to HSP90 was studied in vitro. Selected compounds (5 and 8) were further studied in various tumor cell lines regarding their potential to cause cell growth inhibition, alter the cell cycle profile, inhibit proliferation, and induce apoptosis. Their effect on HSP90 client protein levels was also confirmed in two cell lines. Finally, the antitumor activity of compound 8 was studied in A431 squamous cell carcinoma xenografts in nude mice. Results: Our results indicated that treatment with compounds 5 and 8 decreased the proliferation of tumor cell lines and compound 8 induced apoptosis. In addition, these two compounds were able to downregulate selected proteins known as “clients” of HSP90. Finally, treatment of xenografted mice with compound 5 resulted in a considerable dose-dependent inhibition of tumor growth. Conclusions: Our results show that two new compounds with a chromenopyridinone and thiochromenopyridinone scaffold are promising putative HSP90 inhibitors causing tumor cell growth inhibition.

Automated cell cycle and cell size measurements for single-cell gene expression studies

OBJECTIVES

Recent rise of single-cell studies revealed the importance of understanding the role of cell-to-cell variability, especially at the transcriptomic level. One of the numerous sources of cell-to-cell variation in gene expression is the heterogeneity in cell proliferation state. In order to identify how cell cycle and cell size influences gene expression variability at the single-cell level, we provide an universal and automatic toxic-free label method, compatible with single-cell high-throughput RT-qPCR. The method consists of isolating cells after a double-stained, analyzing their morphological parameters and performing a transcriptomic analysis on the same identified cells.

RESULTS

This led to an unbiased gene expression analysis and could be also used for improving single-cell tracking and imaging when combined with cell isolation. As an application for this technique, we showed that cell-to-cell variability in chicken erythroid progenitors was negligibly influenced by cell size nor cell cycle.

Deletion of TLS polymerases promotes homologous recombination in Arabidopsis

Unrepaired DNA damage hinders the maintenance of genome integrity because it blocks the catalytic activity of replicase. The stalled replication fork can be processed through either translesion synthesis (TLS) with specific polymerases, or replication using the undamaged template. To investigate how TLS activities are regulated and how the stalled replication fork is processed in plants, reversion frequencies and homologous recombination (HR) frequencies were analyzed using GUS-based substrates. The HR frequencies in plants deficient in DNA polymerase ζ (Pol ζ) or Rev1 were higher than that in wildtype plants under normal conditions, and were significantly increased by ultraviolet light irradiation. Heat shock protein (HSP) 90 is known to be involved in various stress responses. To examine the role of HSP90 in the regulation of damage tolerance, we analyzed reversion frequencies and HR frequencies in plants grown in the presence of a HSP inhibitor, geldanamycin (GDA). Reversion frequency was lower in GDA-treated plants than in mock-treated plants. Though the HR frequency was higher in GDA-treated wildtype plants than in mock-treated plants, no significant difference was detected in Rev1-deficient plants. In yeast, TLS polymerases interacted with each other or with a replication clump component, proliferating cell nuclear antigen (PCNA). HSP90 interacted with REV1 or REV7 in Nicotiana benthamiana cells. These results suggest that HSP90 interacts with TLS polymerase(s), which promotes error-prone TLS in plants.

Genome-wide analysis of the Brachypodium distachyon (L.) P. Beauv. Hsp90 gene family reveals molecular evolution and expression profiling under drought and salt stresses

The structure, evolution, and function of heat shock proteins 90 (Hsp90s) have been investigated in great detail in fungi and animals. However, studies on the Hsp90 genes in plants are generally limited. Brachypodium distachyon (L.) P. Beauv., as a model plant for cereal crops, has become a potential biofuel grass. During its long evolution, the Hsp90 gene family in Brachypodium has developed some strategies to cope with adverse environments. How the Hsp90 gene family in Brachypodium evolved in different plant lineages and what its role is in plant responses to drought and salt stresses remains to be elucidated. We used a set of different bioinformatics tools to identify 94 Hsp90 genes from 10 species representing four plant lineages and classified into three subgroups. Eight BdHsp90 genes were detected from B. distachyon. The number of exon-intron structures differed in each subgroup, and the motif analysis revealed that these genes were relatively conservative in each group. The fragments duplication and tandem duplication, which are the prime powers for functional diversity, generally occurred during the duplication of the whole plant genome. Transcriptional analysis of the BdHsp90 genes under salt and drought stress conditions indicated that the expression of these genes was delayed or increased at different stress time points; The expression was more affected in that of Bradi3g39630, Bradi4g06370, and Bradi1g30130. Our findings suggest the involvement of BdHsp90s in plant abiotic stress response, and further consolidate our views on the stress response mechanism of Hsp90 in general.

Not changes in membrane fluidity but proteotoxic stress triggers heat shock protein expression in Chlamydomonas reinhardtii

A conserved reaction of all organisms exposed to heat stress is an increased expression of heat shock proteins (HSPs). Several studies have proposed that HSP expression in heat-stressed plant cells is triggered by an increased fluidity of the plasma membrane. Among the main lines of evidence in support of this model are as follows: (a) the degree of membrane lipid saturation was higher in cells grown at elevated temperatures and correlated with a lower amplitude of HSP expression upon a temperature upshift, (b) membrane fluidizers induce HSP expression at physiological temperatures, and (c) membrane rigidifier dimethylsulfoxide dampens heat-induced HSP expression. Here, we tested whether this holds also for Chlamydomonas reinhardtii. We show that heat-induced HSP expression in cells grown at elevated temperatures was reduced because they already contained elevated levels of cytosolic HSP70A/90A that apparently act as negative regulators of heat shock factor 1. We find that membrane rigidifier dimethylsulfoxide impaired translation under heat stress conditions and that membrane fluidizer benzyl alcohol not only induced HSP expression but also caused protein aggregation. These findings support the classical model for the cytosolic unfolded protein response, according to which HSP expression is induced by the accumulation of unfolded proteins. Hence, the membrane fluidity model should be reconsidered.

Melatonin reduces oxidative damage and upregulates heat shock protein 90 expression in cryopreserved human semen

Sperm cells can be damaged during the semen cryopreservation process, decreasing their fertilizing ability. Physical damage and oxidative stress may occur during the freeze-thawing process. Antioxidants such as the native antioxidant melatonin can potentially improve cryopreservation outcomes. In this study, we added melatonin to cryoprotectant to examine its effect on frozen-thawed human sperm. We found that adding 0.1mM melatonin to cryoprotectant significantly increased sperm viability (24.80 ± 0.46% vs. 20.97 ± 1.27%, P < 0.05) and membrane integrity (P < 0.05), and decreased intracellular reactive oxygen species and lipid peroxidation damage. Furthermore, mRNA levels of the transcription factor NF-E2-related factor-2 and its downstream genes were significantly increased. Resistance to oxidative stress was enhanced and expression of the antiapoptotic gene Bcl-2 was increased by inclusion of 0.1mM melatonin in the cryoprotectant. Moreover, 0.1mM melatonin upregulated the expression of heat shock protein 90 (HSP90), which confers resistance to stressors in frozen-thawed sperm. Results obtained upon addition of inhibitors of melatonin receptors (luzindole and 4-P-PDOT) and an HSP90 inhibitor (geldanamycin) in the cryoprotectant demonstrated that melatonin promoted HSP90 translation via the melatonin receptor MT1 and increased adenosine triphosphate levels, thus increasing the viability of thawed sperm.

Disentangling the effect of dietary restriction on mitochondrial function using recombinant inbred mice

Dietary restriction (DR) extends lifespan and healthspan in many species, but precisely how it elicits its beneficial effects is unclear. We investigated the impact of DR on mitochondrial function within liver and skeletal muscle of female ILSXISS mice that exhibit strain-specific variation in lifespan under 40% DR. Strains TejJ89 (lifespan increased under DR), TejJ48 (lifespan unaffected by DR) and TejJ114 (lifespan decreased under DR) were studied following 10 months of 40% DR (13 months of age). Oxygen consumption rates (OCR) within isolated liver mitochondria were unaffected by DR in TejJ89 and TejJ48, but decreased by DR in TejJ114. DR had no effect on hepatic protein levels of PGC-1a, TFAM, and OXPHOS complexes IV. Mitonuclear protein imbalance (nDNA:mtDNA ratio) was unaffected by DR, but HSP90 protein levels were reduced in TejJ114 under DR. Surprisingly hepatic mitochondrial hydrogen peroxide (H₂O₂) production was elevated by DR in TejJ89, with total superoxide dismutase activity and protein carbonyls increased by DR in both TejJ89 and TejJ114. In skeletal muscle, DR had no effect on mitochondrial OCR, OXPHOS complexes or mitonuclear protein imbalance, but H₂O₂ production was decreased in TejJ114 and nuclear PGC-1a increased in TejJ89 under DR. Our findings indicate that hepatic mitochondrial dysfunction associated with reduced lifespan of TejJ114 mice under 40% DR, but similar dysfunction was not apparent in skeletal muscle mitochondria. We highlight tissue-specific differences in the mitochondrial response in ILSXISS mice to DR, and underline the importance and challenges of exploiting genetic heterogeneity to help understand mechanisms of ageing.

Differential Regulation of G1 CDK Complexes by the Hsp90-Cdc37 Chaperone System

Selective recruitment of protein kinases to the Hsp90 system is mediated by the adaptor co-chaperone Cdc37. We show that assembly of CDK4 and CDK6 into protein complexes is differentially regulated by the Cdc37-Hsp90 system. Like other Hsp90 kinase clients, binding of CDK4/6 to Cdc37 is blocked by ATP-competitive inhibitors. Cdc37-Hsp90 relinquishes CDK6 to D3- and virus-type cyclins and to INK family CDK inhibitors, whereas CDK4 is relinquished to INKs but less readily to cyclins. p21CIP1 and p27KIP1 CDK inhibitors are less potent than the INKs at displacing CDK4 and CDK6 from Cdc37. However, they cooperate with the D-type cyclins to generate CDK4/6-containing ternary complexes that are resistant to cyclin D displacement by Cdc37, suggesting a molecular mechanism to explain the assembly factor activity ascribed to CIP/KIP family members. Overall, our data reveal multiple mechanisms whereby the Hsp90 system may control formation of CDK4- and CDK6-cyclin complexes under different cellular conditions.

A chemical compound inhibiting the Aha1-Hsp90 chaperone complex

The eukaryotic Hsp90 chaperone machinery comprises many co-chaperones and regulates the conformation of hundreds of cytosolic client proteins. Therefore, it is not surprising that the Hsp90 machinery has become an attractive therapeutic target for diseases such as cancer. The compounds used so far to target this machinery affect the entire Hsp90 system. However, it would be desirable to achieve a more selective targeting of Hsp90-co-chaperone complexes. To test this concept, in this-proof-of-principle study, we screened for modulators of the interaction between Hsp90 and its co-chaperone Aha1, which accelerates the ATPase activity of Hsp90. A FRET-based assay that monitored Aha1 binding to Hsp90 enabled identification of several chemical compounds modulating the effect of Aha1 on Hsp90 activity. We found that one of these inhibitors can abrogate the Aha1-induced ATPase stimulation of Hsp90 without significantly affecting Hsp90 ATPase activity in the absence of Aha1. NMR spectroscopy revealed that this inhibitory compound binds the N-terminal domain of Hsp90 close to its ATP-binding site and overlapping with a transient Aha1-interaction site. We also noted that this inhibitor does not dissociate the Aha1-Hsp90 complex but prevents the specific interaction with the N-terminal domain of Hsp90 required for catalysis. In consequence, the inhibitor affected the activation and processing of Hsp90-Aha1-dependent client proteins in vivo We conclude that it is possible to abrogate a specific co-chaperone function of Hsp90 without inhibiting the entire Hsp90 machinery. This concept may also hold true for other co-chaperones of Hsp90.

Bioinformatic analysis of pivotal genes associated with septic shock

We aimed to identify important genes associated with septic shock and then explore the possibly significant mechanisms of this disease. We downloaded GSE26440 expression data of samples from 98 children with septic shock and 32 normal controls from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) in samples from patients with septic shock were analyzed in comparison with those in samples from normal controls using a limma package. Functional enrichment analysis for DEGs was performed using DAVID, and a protein–protein interaction (PPI) network was constructed. Upstream transcription factors for DEGs were predicted using the CHIPBase database, and a transcriptional regulation network was constructed. A total of 383 significantly DEGs, including 141 downregulated and 242 upregulated genes, were obtained in the sepsis shock group compared with the normal group. The top five nodes in the PPI network were lysine (K)-specific demethylase 6B (KDM6B), histone deacetylase 2 (HDAC2), V-Myc avian myelocytomatosis viral oncogene homolog (MYC), heat-shock protein 90 kDa alpha (cytosolic), class B member 1 (HSP90AB1), and poly (A)-binding protein, cytoplasmic 1 (PABPC1). Nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB) was the transcription factor targeted by most genes, and it regulated the expression of KDM6B, HDAC2, MYC, HSP90AB1, and PABPC1. In conclusion, KDM6B, HDAC2, MYC, HSP90AB1, and PABPC1 may play important roles in the development of septic shock. Furthermore, NFκB may be involved in septic shock by regulating the expression of KDM6B, HDAC2, MYC, HSP90AB1, and PABPC1.

The Plasticity of the Hsp90 Co-chaperone System

The Hsp90 system in the eukaryotic cytosol is characterized by a cohort of co-chaperones that bind to Hsp90 and affect its function. Although progress has been made regarding the underlying biochemical mechanisms, how co-chaperones influence Hsp90 client proteins in vivo has remained elusive. By investigating the effect of 12 Hsp90 co-chaperones on the activity of different client proteins in yeast, we find that deletion of co-chaperones can have a neutral or negative effect on client activity but can also lead to more active clients. Only a few co-chaperones are active on all clients studied. Closely related clients and even point mutants can depend on different co-chaperones. These effects are direct because differences in client-co-chaperone interactions can be reconstituted in vitro. Interestingly, some co-chaperones affect client conformation in vivo. Thus, co-chaperones adapt the Hsp90 cycle to the requirements of the client proteins, ensuring optimal activation.

Heat Shock Protein 90 Alpha, Lass B Member 1: a Key Regulative Gene of Monitoring Duodenal Tumor for Obesity Induced by High-Fat Diet

BACKGROUND

Effective methods of preventing and treating duodenal carcinoma, especially cancer induced by obesity (resulting from a high-fat diet) remains a longstanding challenge in medicine.

METHODS

With regard to the objective, key genes were explored in the evolutional process in a group of normal, obese (high-fat diet), and duodenal tumor mice. Here, 23 genes were selected by the bioinformatics method. In order to correct the result, verification experiments were performed twice through online analysis.

RESULTS

Finally, heat shock protein 90 alpha class B member 1, enriched in inflammation, tumors and steroid hormones-related pathways, was the statistically different gene in the evolutional process.

CONCLUSIONS

This work provided a new perspective to understand the evolutional process in a group of normal, obese (high-fat diet), and duodenal tumor mice and a potential target gene for monitoring duodenal tumors for normal individuals especially for obesity induced by high-fat diet.

Association of heat stress protein 90 and 70 gene polymorphism with adaptability traits in Indian sheep (Ovis aries)

Heat stress proteins assist cellular proteins in the acquisition of native structure. The present research was conducted to study how thermo-tolerance is modulated by HSP90 and HSP70 gene polymorphism and its association with hemato-physio-biochemical parameters, supported by their expression profiles in Chokla, Magra, Marwari, and Madras Red sheep breeds. Least square analysis revealed significant effect (P < 0.05) of season and breed on all the physiological parameters, i.e., temperature, respiratory rate, and pulse rate (a.m. and p.m.), as well as hematological parameters like Hb, packed cell volume, total erythrocyte count (TEC), neutrophil/lymphocyte (N/L) ratio, and total leukocyte count (TLC). There was a significant influence (P < 0.05) of breed on biochemical parameters such as glucose, SGOT, phosphorous, triglyceride, and cholesterol. Eight fragments were amplified and sequenced in HSP90, and 70 genes and 13 single-nucleotide polymorphisms (SNPs) were identified. Tetra-primer amplification refractory mutation system PCR, PCR-RFLP, and allele-specific PCR genotyping protocols were developed for large-scale genotyping of five SNPs. A significant difference (P < 0.05) of rectal temperature (a.m.), respiratory rate (p.m.), triglyceride, and total protein was observed at SNP01; albumin at SNP2; pulse rate (p.m.) at SNP3; and rectal temperature (p.m.), pulse rate (p.m.), Hb (g/dL), and N/L ratio at SNP4 and TLC at SNP5. Gene expression analysis revealed higher expression in less adapted animals with Madras Red < Magra < Chokla < Marwari expression pattern [corrected]. Predominant allele was found to be superior in most of the SNPs (SNP1-4) indicating the selection acting in directional manner (positive selection). Finally, it is concluded that TACCA haplotype combination of SNP1-SNP2-SNP3-SNP4-SNP5 might be of some selection advantage for the identification of animals more adaptable to heat stress.

Differential expression of myocardial heat shock proteins in rats acutely exposed to fluoride

Acute fluoride (F-) toxicity is known to cause severe cardiac complications and leads to sudden heart failure. Previously, we reported that increased myocardial oxidative damage, apoptosis, altered cytoskeleton and AMPK signaling proteins associated with energy deprivation in acute F- induced cardiac dysfunction. The present study was aimed to decipher the status of myocardial heat shock proteins (Hsps-Hsp27, Hsp32, Hsp40, Hsp60, Hsp70, Hsp90) and heat shock transcription factor 1 (Hsf1) in acute F--intoxicated rats. In order to study the expression of myocardial Hsps, male Wistar rats were treated with single oral doses of 45 and 90 mg/kg F- for 24 h. The expression levels of myocardial Hsps were determined using RT-PCR, western blotting, and immunohistochemical studies. Acute F--intoxicated rats showed elevated levels of both the transcripts and protein expression of Hsf1, Hsp27, Hsp32, Hsp60, and Hsp70 when compared to control. In addition, the expression levels of Hsp40 and Hsp90 were significantly declined in a dose-dependent fashion in F--treated animals. Our result suggests that differential expression of Hsps in the rat myocardium could serve as a balance between pro-survival and death signal during acute F--induced heart failure.

A pyrrole-based natural small molecule mitigates HSP90 expression in MDA-MB-231 cells and inhibits tumor angiogenesis in mice by inactivating HSF-1

Heat shock proteins (HSPs), molecular chaperones, are crucial for the cancer cells to facilitate proper functioning of various oncoproteins involved in cell survival, proliferation, migration, and tumor angiogenesis. Tumor cells are said to be "addicted" to HSPs. HSPs are overexpressed in many cancers due to upregulation of transcription factor Heat-shock factor 1 (HSF-1), the multifaceted master regulator of heat shock response. Therefore, pharmacological targeting of HSPs via HSF-1 is an effective strategy to treat malignant cancers like triple negative breast cancer. In the current study, we evaluated the efficacy of a pyrrole derivative [bis(2-ethylhexyl)1H-pyrrole-3,4-dicarboxylate], TCCP, purified from leaves of Tinospora cordifolia for its ability to suppress heat shock response and angiogenesis using MDA-MB-231 cells and the murine mammary carcinoma: Ehrlich ascites tumor model. HSP90 was downregulated by TCCP by inactivation of HSF-1 resulting in inhibition of tumor cell proliferation, VEGF-induced cell migration, and concomitant decrease in tumor burden and neo-angiogenesis in vivo. The mechanism of suppression of HSPs involves inactivation of PI3K/Akt and phosphorylation on serine 307 of HSF-1 by the activation of ERK1. HSF-1 and HSP90 and 70 localization and expression were ascertained by immunolocalization, immunoblotting, and qPCR experiments. The anti-angiogenic effect of TCCP was studied in vivo in tumor-bearing mice and ex vivo using rat corneal micro-pocket assay. All the results thus corroborate the logic behind inactivating HSF-1 using TCCP as an alternative approach for cancer therapy.

Dietary enzymatically treated Artemisia annua L. supplementation alleviates liver oxidative injury of broilers reared under high ambient temperature

Heat stress induced by high ambient temperature is a major concern in commercial broiler production. To evaluate the effects of dietary enzymatically treated Artemisia annua L. (EA) supplementation on growth performance and liver oxidative injury of broilers reared under heat stress, a total of 320 22-day-old male broilers were randomly allotted into five groups with eight replicates of eight birds each. Broilers in the control group were housed at 22 ± 1 °C and fed the basal diet. Broilers in the HS, HS-EA1, HS-EA2, and HS-EA3 groups were fed basal diet supplemented with 0, 0.75, 1.00, and 1.25 g/kg EA, respectively, and reared under cyclic high temperature (34 ± 1 °C for 8 h/day and 22 ± 1 °C for 16 h/day). Broilers fed EA diets had higher final body weight, average daily body weight gain, and average daily feed intake, as well as liver concentration of reduced glutathione, activities of antioxidant enzymes, abilities to inhibit hydroxyl radical and superoxide radical (HS-EA2 and HS-EA3), and lower liver concentrations of reactive oxygen metabolites, malondialdehyde, and protein carbonyl (HS-EA1, HS-EA2, and HS-EA3) than HS group (P < 0.05). EA treatment downregulated the mRNA levels of heat shock proteins 70 and 90, upregulated the mRNA levels of nuclear factor erythroid 2-related factor 2 (HS-EA1, HS-EA2, and HS-EA3) and heme oxygenase 1 (HS-EA2 and HS-EA3) in liver of heat-treated broilers (P < 0.05). In conclusion, EA alleviated heat stress-induced growth depression and liver oxidative injury in broilers, possibly through improving the antioxidant capacity and regulating the pertinent mRNA expression. The appropriate inclusion level of EA in broiler diet is 1.00-1.25 g/kg.

Expression dynamics of HSP90 and nitric oxide synthase (NOS) isoforms during heat stress acclimation in Tharparkar cattle

Six male Tharparkar cattle of 2-3 years old were selected for the study. After 15-day acclimation at thermoneutral zone (TNZ) in psychrometric chamber, animals were exposed at 42 °C for 6 h up to 23 days followed by 12 days of recovery period. Blood samples were collected during control period at TNZ (days 1, 5, and 12), after heat stress exposure (day 1, immediate heat stress acclimation (IHSA); days 2 to 10, short-term heat stress acclimation (STHSA); days 15 to 23, long-term heat stress acclimation (LTHSA); days 7 and 12, recovery period), and peripheral blood mononuclear cells (PBMCs) were isolated for RNA and protein extraction. The messenger RNA (mRNA) and protein expression in PBMCs were determined by qPCR and western blot, respectively. Samples at TNZ were taken as control. The mRNA expression of HSP90, iNOS, and eNOS was significantly upregulated (P < 0.05) on day 1 (ISHA) as compared to control, remained consistent during STHSA, again increased during LTHSA, and finally reduced to basal level during recovery period. The protein expression of HSP90, iNOS, and eNOS were akin to their transcript pattern. PBMC culture study was conducted to study transcriptional abundance of HSP90, iNOS, and eNOS at different temperature-time combinations. The present findings indicate that HSP90, iNOS, and eNOS could possibly play an important role in mitigating thermal insults and confer thermotolerance during long-term heat stress exposure in Tharparkar cattle.

Cloning of HSP90, expression and localization of HSP70/90 in different tissues including lactating/non-lactating yak (Bos grunniens) breast tissue

The aim of this study is to investigate the expression and localization of HSP70/90 in different tissues and explore the regulation effects of HSP70/90 at lactation period of female yaks. HSP90 mRNA was cloned from the heart samples of female yaks, Quantitative real-time (qRT-PCR), Western blotting (WB), immunohistochemistry and immunofluorescence assays were utilized to analyze the expressions of HSP70/90 mRNA and protein in different tissues. Sequence analysis showed that HSP90 is a conserved molecular chaperone of female yaks. The qRT-PCR, WB results showed that the expressions of HSP70/90 mRNA and protein were significantly different in different tissues, and 3-fold higher expression during the lactation period than the non-lactation period of breast tissue (P < 0.01). Immunohistochemistry and immunofluorescence assays results showed that HSP70/90 were located in the cardiac muscle cells, cerebellar medulla, theca cells lining at the reproductive system, and the mammary epithelia of the breasts. In addition, the expression level of HSP70 was higher than those of HSP90 in all examined tissues. Therefore, our results strongly suggest that the expression and localization of HSP70/90 could provide significant evidence to further research in tissue specific expression, and lactation function of female yaks.

Inhibition of heat shock protein 90 rescues glucocorticoid-induced bone loss through enhancing bone formation

Endogenous glucocorticoids (GCs) support normal bone development and bone mass maintenance, whereas long-term exposure to pharmacological dosages of GCs uncouples bone formation and resorption, resulting in GC-induced osteoporosis (GIOP). Heat shock protein 90 (HSP90) chaperoning glucocorticoid receptor (GR) signaling prompts us to speculate that HSP90 plays critical roles in GC-mediated bone formation and GIOP. In the present study, inhibition of HSP90 activity by 17-Demethoxy-17-allyaminogeldanmycin (17-AAG) or knockdown of HSP90 expression by siRNAs attenuated dexamethasone(Dex)-induced GR nuclear accumulation and transcriptional output of GR signaling, whereas overexpression of HSP90α or HSP90β enhanced GR transactivity in C3H10T1/2 cells. Though 17-AAG itself enhanced osteoblastic differentiation, it restored the Dex(10-8M)-induced and Dex(10-6M)-negated osteoblastic differentiation in C3H10T1/2 cells and primary calvarial osteoblasts. Moreover, systemic administration of 17-AAG to mice induced not only osteoclastogenesis but also osteoblastogenesis, whereas bone formation possibly exceeded bone resorption, eventually leading to the increased bone masses. Likewise, systemic administration of 17-AAG to mice restored GC-negated osteoblastogenesis and enhanced GC-induced osteoclastogenesis, similarly, 17-AAG-induced bone formation possibly exceeded both 17-AAG- and GC-induced bone resorption, eventually resulting in rescue of GIOP. Together, the present study has revealed that inhibition of HSP90 restores GIOP through enhancing bone formation, and our findings may help to shed light on the pathogenesis of GIOP and provide targets for the therapeutic intervention of the disease.

Cloning of three heat shock protein genes (HSP70, HSP90α and HSP90β) and their expressions in response to thermal stress in loach (Misgurnus anguillicaudatus) fed with different levels of vitamin C

Heat shock protein 70 (HSP70) and 90 (HSP90) are the most broadly studied proteins in HSP families. They play key roles in cells as molecular chaperones, in response to stress conditions such as thermal stress. In this study, full-length cDNA sequences of HSP70, HSP90α and HSP90β from loach Misgurnus anguillicaudatus were cloned. The full-length cDNA of HSP70 in loach was 2332bp encoding 644 amino acids, while HSP90α and HSP90β were 2586bp and 2678bp in length, encoding 729 and 727 amino acids, respectively. The deduced amino acid sequences of HSP70 in loach shared the highest identity with those of Megalobrama amblycephala and Cyprinus carpio. The deduced amino acid sequences of HSP90α and HSP90β in loach both shared the highest identity with those of M. amblycephala. Their mRNA tissue expression results showed that the maximum expressions of HSP70, HSP90α and HSP90β were respectively present in the intestine, brain and kidney of loach. Quantitative real-time PCR was employed to analyze the temporal expressions of HSP70, HSP90α and HSP90β in livers of loaches fed with different levels of vitamin C under thermal stress. Expression levels of the three HSP genes in loach fed the diet without vitamin C supplemented at 0 h of thermal stress were significantly lower than those at 2 h, 6 h, 12 h and 24 h of thermal stress. It indicated that expressions of the three HSP genes were sensitive to thermal stress in loach. The three HSP genes in loaches fed with 1000 mg/kg vitamin C expressed significantly lower than other vitamin C groups at many time points of thermal stress, suggesting 1000 mg/kg dietary vitamin C might decrease the body damages caused by the thermal stress. This study will be of value for further studies into thermal stress tolerance in loach.

The Role of DAF-21/Hsp90 in Mouth-Form Plasticity in Pristionchus pacificus

Phenotypic plasticity is increasingly recognized to facilitate adaptive change in plants and animals, including insects, nematodes, and vertebrates. Plasticity can occur as continuous or discrete (polyphenisms) variation. In social insects, for example, in ants, some species have workers of distinct size classes while in other closely related species variation in size may be continuous. Despite the abundance of examples in nature, how discrete morphs are specified remains currently unknown. In theory, polyphenisms might require robustness, whereby the distribution of morphologies would be limited by the same mechanisms that execute buffering from stochastic perturbations, a function attributed to heat-shock proteins of the Hsp90 family. However, this possibility has never been directly tested because plasticity and robustness are considered to represent opposite evolutionary principles. Here, we used a polyphenism of feeding structures in the nematode Pristionchus pacificus to test the relationship between robustness and plasticity using geometric morphometrics of 20 mouth-form landmarks. We show that reducing heat-shock protein activity, which reduces developmental robustness, increases the range of mouth-form morphologies. Specifically, elevated temperature led to a shift within morphospace, pharmacological inhibition of all Hsp90 genes using radicicol treatment increased shape variability in both mouth-forms, and CRISPR/Cas9-induced Ppa-daf-21/Hsp90 knockout had a combined effect. Thus, Hsp90 canalizes the morphologies of plastic traits resulting in discrete polyphenism of mouth-forms.

Production and purification of human Hsp90β in Escherichia coli

The molecular chaperone Hsp90 is an essential member of the cellular proteostasis system. It plays an important role in the stabilisation and activation of a large number of client proteins and is involved in fatal disease processes, e.g. Alzheimer disease, cancer and cystic fibrosis. This makes Hsp90 a crucial protein to study. Mechanistic studies require large amounts of protein but the production and purification of recombinant human Hsp90 in Escherichia coli is challenging and laborious. Here we identified conditions that influence Hsp90 production, and optimised a fast and efficient purification protocol. We found that the nutrient value of the culturing medium and the length of induction had significant effect on Hsp90 production in Escherichia coli. Our fast, single-day purification protocol resulted in a stable, well-folded and pure sample that was resistant to degradation in a reproducible manner. We anticipate that our results provide a useful tool to produce higher amount of pure, well-folded and stable recombinant human Hsp90β in Escherichia coli in an efficient way.

HSP90 stabilizes auxin receptor TIR1 and ensures plasticity of auxin responses

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that facilitates the maturation of target proteins. Here, we report that the auxin receptor TIR1 is a target of cytosolic HSP90 and that HSP90 and TIR1 form a complex. Inhibition of HSP90 compromised the nuclear localization of TIR1, and abrogated plant responses to the hormone auxin. Our findings suggest that HSP90 positively regulates auxin receptor function. We also propose that HSP90 buffers or hides phenotypic variations in animals and plants by masking mutations in some of its target proteins. Support for this proposal comes from the tir1-1 mutant of Arabidopsis, which showed a root growth defect that was only seen after inhibition of HSP90. We have developed a model in which cytosolic HSP90 works like a capacitor for auxin-related phenotypic variation via regulation of the auxin receptor in response to environmentally and genetically induced perturbations.

HOP3 a new regulator of the ER stress response in Arabidopsis with possible implications in plant development and response to biotic and abiotic stresses

HOPs (heat shock protein 70 (HSP70)-heat shock protein 90 (HSP90) organizing proteins) are a highly conserved family of cytosolic cochaperones. In a recent study we showed that HOP3, a member of the HOP family in Arabidopsis, plays an essential role during endoplasmic reticulum (ER) stress in plants. Interestingly, we also demonstrated that AtHOP3 interacts with binding immunoglobulin protein (BiP), a major ER-resident chaperone. All these data suggest that HOP3 could assist BiP in protein folding in the ER. These findings open the exciting possibility that HOP3, through its role in the alleviation of ER stress, could play an important function during different developmental processes and in response to different biotic and abiotic stresses.

The six Tomato yellow leaf curl virus genes expressed individually in tomato induce different levels of plant stress response attenuation

Tomato yellow leaf curl virus (TYLCV) is a begomovirus infecting tomato plants worldwide. TYLCV needs a healthy host environment to ensure a successful infection cycle for long periods. Hence, TYLCV restrains its destructive effect and induces neither a hypersensitive response nor cell death in infected tomatoes. On the contrary, TYLCV counteracts cell death induced by other factors, such as inactivation of HSP90 functionality. Suppression of plant death is associated with the inhibition of the ubiquitin 26S proteasome degradation and with a deactivation of the heat shock transcription factor HSFA2 pathways (including decreased HSP17 levels). The goal of the current study was to find if the individual TYLCV genes were capable of suppressing HSP90-dependent death and HSFA2 deactivation. The expression of C2 (C3 and CP to a lesser extent) caused a decrease in the severity of death phenotypes, while the expression of V2 (C1 and C4 to a lesser extent) strengthened cell death. However, C2 or V2 markedly affected stress response under conditions of viral infection. The downregulation of HSFA2 signaling, initiated by the expression of C1 and V2, was detected in the absence of virus infection, but was enhanced in infected plants, while CP and C4 mitigated HSFA2 levels only in the infected tomatoes. The dependence of analyzed plant stress response suppression on the interaction of the expressed genes with the environment created by the whole virus infection was more pronounced than on the expression of individual TYLCV genes.

Heat shock proteins and kidney disease: perspectives of HSP therapy

Heat shock proteins (HSPs) mediate a diverse range of cellular functions, prominently including folding and regulatory processes of cellular repair. A major property of these remarkable proteins, dependent on intracellular or extracellular location, is their capacity for immunoregulation that optimizes immune activity while avoiding hyperactivated inflammation. In this review, recent investigations are described, which examine roles of HSPs in protection of kidney tissue from various traumatic influences and demonstrate their potential for clinical management of nephritic disease. The HSP70 class is particularly attractive in this respect due to its multiple protective effects. The review also summarizes current understanding of HSP bioactivity in the pathophysiology of various kidney diseases, including acute kidney injury, diabetic nephropathy, chronic glomerulonephritis, and lupus nephritis-along with other promising strategies for their remediation, such as DNA vaccination.

A norepinephrine-responsive miRNA directly promotes CgHSP90AA1 expression in oyster haemocytes during desiccation

Oyster Crassostrea gigas is one model mollusc inhabiting in the intertidal zone and is frequently stressed by desiccation. The adaptation mechanism of oyster to environmental stress involves multiple levels, and miRNA is one of the most important regulators in post-transcriptional level. In the present study, an oyster norepinephrine-responsive miRNA cgi-miR-365 was proved to contribute to the host adaptation against desiccation by directly promoting the expression of CgHSP90AA1. Briefly, a significant increase of cgi-miR-365 was observed from the first day after aerial exposure and the up-regulation was vigorously repressed when oysters were injected with adrenoceptors antagonists. A total of 15 genes involved in biological regulation, metabolic process and response to stimulus were predicted to be modulated by cgi-miR-365. Among these genes, CgHSP90AA1 was up-regulated significantly during desiccation and could be down-regulated after simultaneous injection of adrenoceptors antagonists. The interaction between cgi-miR-365 and CgHSP90AA1 was subsequently verified in vitro, and a significant promotion of CgHSP90AA1 transcripts was observed after overexpressing cgi-miR-365 in either in vitro luciferase reporter assay or primarily cultured haemocytes. Meanwhile, CgHSP90AA1 transcripts decreased in vivo when cgi-miR-365 was repressed by its inhibitor during desiccation. Collectively, it was suggested that cgi-miR-365 could be induced by norepinephrine during desiccation and promote CgHSP90AA1 expression directly after binding to its 3'-UTR, which would provide new evidence in miRNA-mediated adaptation mechanism in oysters against intertidal stress.

A Systems Biology Approach Using Transcriptomic Data Reveals Genes and Pathways in Porcine Skeletal Muscle Affected by Dietary Lysine

Nine crossbred finishing barrows (body weight 94.4 ± 6.7 kg) randomly assigned to three dietary treatments were used to investigate the effects of dietary lysine on muscle growth related metabolic and signaling pathways. Muscle samples were collected from the longissimus dorsi of individual pigs after feeding the lysine-deficient (4.30 g/kg), lysine-adequate (7.10 g/kg), or lysine-excess (9.80 g/kg) diet for five weeks, and the total RNA was extracted afterwards. Affymetrix Porcine Gene 1.0 ST Array was used to quantify the expression levels of 19,211 genes. Statistical ANOVA analysis of the microarray data showed that 674 transcripts were differentially expressed (at p ≤ 0.05 level); 60 out of 131 transcripts (at p ≤ 0.01 level) were annotated in the NetAffx database. Ingenuity pathway analysis showed that dietary lysine deficiency may lead to: (1) increased muscle protein degradation via the ubiquitination pathway as indicated by the up-regulated DNAJA1, HSP90AB1 and UBE2B mRNA; (2) reduced muscle protein synthesis via the up-regulated RND3 and ZIC1 mRNA; (3) increased serine and glycine synthesis via the up-regulated PHGDH and PSPH mRNA; and (4) increased lipid accumulation via the up-regulated ME1, SCD, and CIDEC mRNA. Dietary lysine excess may lead to: (1) decreased muscle protein degradation via the down-regulated DNAJA1, HSP90AA1, HSPH1, and UBE2D3 mRNA; and (2) reduced lipid biosynthesis via the down-regulated CFD and ME1 mRNA. Collectively, dietary lysine may function as a signaling molecule to regulate protein turnover and lipid metabolism in the skeletal muscle of finishing pigs.

Tenofovir and adefovir down-regulate mitochondrial chaperone TRAP1 and succinate dehydrogenase subunit B to metabolically reprogram glucose metabolism and induce nephrotoxicity

Despite the therapeutic success of tenofovir (TFV) for treatment of HIV-1 infection, numerous cases of nephrotoxicity have been reported. Mitochondrial toxicity has been purported as the major target of TFV-associated renal tubulopathy but the underlying molecular mechanism remains unclear. In this report, we use metabolomics and proteomics with HK-2 cells and animal models to dissect the molecular pathways underlying nephropathy caused by TFV and its more toxic analog, adefovir (ADV). Proteomic analysis shows that mitochondrial chaperone TRAP1 and mtDNA replicating protein SSBP1 were significantly down-regulated in TFV and ADV treated HK-2 cells compared with controls. Transmission electron microscopy (TEM) revealed that TFV and ADV-treated HK-2 cells had accumulated glycogen, a phenotype that was also observed in mice treated with TFV and ADV. Analysis of the proteins in TCA cycle showed succinate dehydrogenase subunit B (SDHB) was nearly depleted in glucose oxidative phosphorylation pathway however certain enzymes in the glycolysis and glycogen synthesis pathway had elevated expression in TFV and ADV-treated HK-2 cells. These results suggest that TFV and ADV may cause mitochondrial dysfunction in renal tubular cells and reprogramming of glucose metabolism. The resulting glycogen accumulation may partially contribute to TFV and ADV induced renal dysfunction.

Effect of ammonia on the gene expression levels of the freshwater cyclopoid Eucyclops serrulatus

Ammonia pollution is a critical issue in Europe, since more than half of the European freshwater bodies actually fail to meet EU quality standards for this chemical. In this study, the response of stress-related genes to a sublethal ammonia concentration has been investigated in the adults of the freshwater cyclopoid Eucyclops serrulatus. Two short-term exposures (12h and 24h) at 12mg/L NH₄⁺ have been tested. Results indicate that 12mg/L NH₄⁺ causes a significant increase in the expression of some proteins, namely CAT, HSP90 and HSP40, suggesting an activation of the protecting antioxidant system after both 12h and 24h.

Evolutionarily conserved dual lysine motif determines the non-chaperone function of secreted Hsp90alpha in tumour progression

Both intracellular and extracellular heat shock protein-90 (Hsp90) family proteins (α and β) have been shown to support tumour progression. The tumour-supporting activity of the intracellular Hsp90 is attributed to their N-terminal ATPase-driven chaperone function. What molecular entity determines the extracellular function of secreted Hsp90 and the distinction between Hsp90α and Hsp90β was unclear. Here we demonstrate that CRISPR/Case9 knocking out Hsp90α nullifies tumour cells' ability to migrate, invade and metastasize without affecting the cell survival and growth. Knocking out Hsp90β leads to tumour cell death. Extracellular supplementation with recombinant Hsp90α, but not Hsp90β, protein recovers tumourigenicity of the Hsp90α-knockout cells. Sequential mutagenesis identifies two evolutionarily conserved lysine residues, lys-270 and lys-277, in the Hsp90α subfamily that determine the extracellular Hsp90α function. Hsp90β subfamily lacks the dual lysine motif and the extracellular function. Substitutions of gly-262 and thr-269 in Hsp90β with lysines convert Hsp90β to a Hsp90α-like protein. Newly constructed monoclonal antibody, 1G6-D7, against the dual lysine region of secreted Hsp90α inhibits both de novo tumour formation and expansion of already formed tumours in mice. This study suggests an alternative therapeutic approach to target Hsp90 in cancer, that is, the tumour-secreted Hsp90α, instead of the intracellular Hsp90α and Hsp90β.

Optogenetic control with a photocleavable protein, PhoCl

To expand the range of experiments that are accessible with optogenetics, we developed a photocleavable protein (PhoCl) that spontaneously dissociates into two fragments after violet-light-induced cleavage of a specific bond in the protein backbone. We demonstrated that PhoCl can be used to engineer light-activatable Cre recombinase, Gal4 transcription factor, and a viral protease that in turn was used to activate opening of the large-pore ion channel Pannexin-1.

1,4-Naphthoquinone activates the HSP90/HSF1 pathway through the S-arylation of HSP90 in A431 cells: Negative regulation of the redox signal transduction pathway by persulfides/polysulfides

The current consensus is that environmental electrophiles activate redox signal transduction pathways through covalent modification of sensor proteins with reactive thiol groups at low concentrations, while they cause cell damage at higher concentrations. We previously exposed human carcinoma A431 cells to the atmospheric electrophile 1,4-naphthoquinone (1,4-NQ) and found that heat shock protein 90 (HSP90), a negative regulator of heat shock factor 1 (HSF1), was a target of 1,4-NQ. In the study presented here, we determined whether 1,4-NQ activates HSF1. We also examined whether such redox signaling could be regulated by nucleophilic sulfur species. Exposure of A431 cells to 1,4-NQ covalently modified cellular HSP90, resulting in repression of the association between HSF1 with HSP90, thereby enhancing HSF1 translocation into the nuclei. Liquid chromatography-tandem mass spectrometry analysis with recombinant HSP90 revealed that the modifications site were Cys412 and Cys564. We found that HSF1 activation mediated by 1,4-NQ upregulated downstream genes, such as HSPA6. HSF1 knockdown accelerated 1,4-NQ-mediated cytotoxicity in the cells. While simultaneous treatment with reactive persulfide and polysulfide, Na₂S₂ and Na₂S₄, blocked 1,4-NQ-dependent protein modification and HSF1 activation in A431 cells, the knockdown of Cys persulfide producing enzymes cystathionine β-synthase (CBS) and/or cystathionine γ-lyase (CSE) enhanced these phenomena. 1,4-NQ-thiol adduct and 1,4-NQ-S-1,4-NQ adduct were produced during the enzymatic reaction of recombinant CSE in the presence of 1,4-NQ. The results suggest that activation of the HSP90-HSF1 signal transduction pathway mediated by 1,4-NQ protects cells against 1,4-NQ and that per/polysulfides can diminish the reactivity of 1,4-NQ by forming sulfur adducts.

[Effects of Electroacupuncture and Moxibustion Pretreatment on Expressions of HSP 27, HSP 70, HSP 90 at Different Time-points in Rabbits with Myocardial Ischemia-reperfusion Injury]

OBJECTIVE

To observe the effect of electroacupuncture (EA) and moxibustion (Moxi) pretreatment on expression of myocardial heat shock protein (HSP) in acute myocardial ischemia-reperfusion injury (MIRI) rabbits.

METHODS

A total of 72 New Zealand rabbits were randomly divided into 4 groups:sham operation, MIRI model, EA pretreatment and Moxi pretreatment (n=18 rabbits in each group) which were further divided into 0, 24 and 48 h (time-point) subgroups (n=6 in each). The MIRI model was established by occlusion of the anterior descending branch (ADB) of the left coronary artery for 40 min and reperfusion for 60 min. EA and Moxi stimulation was respectively applied to bilateral "Neiguan"(PC 6) for 20 min, once daily for 5 days before ADB occlusion. The expressions of myocardial HSP 27, HSP 70 and HSP 90 were detected by immunohistochemistry. The pathological and ultrastructural changes of left ventricular ischemia tissue were observed under light and transmission electronic microscope (TEM), respectively.

RESULTS

Outcomes of H.E. staining and ultrastructure showed that MIRI-induced changes of disordered arrangement of cardiomyocytes, vague myocardial transverse striation, inflammatory infiltration, cardiac myofibre necrosis and fibrolysis (light microscope), and myofiber atrophy, vague and disorder in the arrangement of myofiber, myofilament necrosis, interstitial edema, mitochondrial swelling, microvessel expansion, etc. (TEM) were relatively milder in both EA and Moxi pretreatment groups (48 h). In comparison with the sham group, the expression levels of myocardial HSP 27, HSP 70 and HSP 90 had no significant changes after MIRI at the 3 time-points (P>0.05). In the pretreatment groups, the expression levels of HSP 27 at 24 and 48 h in both EA and Moxi groups, HSP 70 at 48 h in both groups, HSP 70 at 0 and 24 h in the Moxi group were significantly up-regulated compared with the model group (P<0.05, P<0.01). No significant changes were found in the expression of HSP 90 at the 3 time-points in the EA and Moxi pretreatment groups (P>0.05). No significant differences were found between EA and Moxi in up-regulating expressions of myocardial HSP 27, HSP 70 and HSP 90 proteins at the 3 time-points (P>0.05) except HSP 70 at 24 h (Moxi being stronger relative to EA, P<0.05).

CONCLUSIONS

EA and Moxi pretreatment has a protective effect on ischemic myocardium in MIRI rabbits, which Feb be associated with their actions in up-regulating myocardial HSP 27 and HSP 70 expression.

Ammonia stress under high environmental ammonia induces Hsp70 and Hsp90 in the mud eel, Monopterus cuchia

The obligatory air-breathing mud eel (Monopterus cuchia) is frequently being challenged with high environmental ammonia (HEA) exposure in its natural habitats. The present study investigated the possible induction of heat shock protein 70 and 90 (hsp70, hsc70, hsp90α and hsp90β) genes and more expression of Hsp70 and Hsp90 proteins under ammonia stress in different tissues of the mud eel after exposure to HEA (50 mM NH₄Cl) for 14 days. HEA resulted in significant accumulation of toxic ammonia in different body tissues and plasma, which was accompanied with the stimulation of oxidative stress in the mud eel as evidenced by more accumulation of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) during exposure to HEA. Further, hyper-ammonia stress led to significant increase in the levels of mRNA transcripts for inducible hsp70 and hsp90α genes and also their translated proteins in different tissues probably as a consequence of induction of hsp70 and hsp90α genes in the mud eel. However, hyper-ammonia stress was neither associated with any significant alterations in the levels of mRNA transcripts for constitutive hsc70 and hsp90β genes nor their translated proteins in any of the tissues studied. More abundance of Hsp70 and Hsp90α proteins might be one of the strategies adopted by the mud eel to defend itself from the ammonia-induced cellular damages under ammonia stress. Further, this is the first report of ammonia-induced induction of hsp70 and hsp90α genes under hyper-ammonia stress in any freshwater air-breathing teleost.

hsp90 and hsp47 appear to play an important role in minnow Puntius sophore for surviving in the hot spring run-off aquatic ecosystem

Changes in the expression of a number of hsp genes in minnow Puntius sophore collected from a hot spring run-off (Atri hot spring in Odisha, India; 20^o09'N 85^°18'E, 36-38 °C) were investigated to study the upper thermal acclimation response under heat stress, using same species from aquaculture ponds (water temperature 27 °C) as control. Expression of hsp genes was analyzed in both groups using RT-qPCR, which showed up-regulation of hsp90 (2.1-fold) and hsp47 (2.5-fold) in hot spring run-off fishes, whereas there was no alteration in expression of other hsps. As the fish inhabit the hot spring run-off area for very long duration, they could have adapted to the environment. To test this hypothesis, fishes collected from hot spring run-off were divided into two groups; one was heat-shocked at 41 °C/24 h, and the other was acclimatized at 27 °C/24 h. Up-regulation of all the hsps (except hsp78) was observed in the heat-shocked fishes, whereas expression of all hsps was found to be down-regulated to the basal level in fishes maintained at 27 °C/24 h. Pathway analysis showed that the expressions of all the hsps except hsp90 are regulated by the transcription factor heat shock factor 1 (Hsf1). This study showed that hsp90 and hsp47 play an important role in Puntius sophore for surviving in the high-temperature environment of the hot spring run-off. Additionally, we show that plasticity in hsp gene expression is not lost in the hot spring run-off population.

Inhibition of hepatitis C virus using siRNA targeted to the virus and Hsp90

Hepatitis C (HCV) is a viral disease affecting millions of people worldwide, and persistent HCV infection can lead to progressive liver disease with the development of liver cirrhosis and hepatocellular carcinoma. During treatment for hepatitis C, the occurrence of viral resistance is common. To reduce the occurrence of resistance, new viral treatments should target both viral and cellular factors. Many interactions occur between viral and host proteins during the HCV replication cycle and might be used for the development of new therapies against hepatitis C. Heat shock protein 90 (Hsp90) plays a role in the folding of cellular and viral proteins and also interacts with HCV proteins. In the present study, we knocked down the expression of the Hsp90 gene and inhibited viral replication using siRNA molecules. Reducing the expression of Hsp90 successfully decreased HCV replication. All siRNA molecules specific to the viral genome showed the efficient inhibition of viral replication, particularly siRNA targeted to the 5'UTR region. The combination of siRNAs targeting the viral genome and Hsp90 mRNA also successfully reduced HCV replication and reduced the occurrence of viral resistance. Moreover, these results suggest that an approach based on the combination of cellular and viral siRNAs can be used as an effective alternative for hepatitis C viral suppression.

Cadmium in vivo exposure alters stress response and endocrine-related genes in the freshwater snail Physa acuta. New biomarker genes in a new model organism

The freshwater snail Physa acuta is a sensitive organism to xenobiotics that is appropriate for toxicity testing. Cadmium (Cd) is a heavy metal with known toxic effects on several organisms, which include endocrine disruption and activation of the cellular stress responses. There is scarce genomic information on P. acuta; hence, in this work, we identify several genes related to the hormonal system, the stress response and the detoxification system to evaluate the effects of Cd. The transcriptional activity of the endocrine-related genes oestrogen receptor (ER), oestrogen-related receptor (ERR), and retinoid X receptor (RXR), the heat shock proteins genes hsp70 and hsp90 and a metallothionein (MT) gene was analysed in P. acuta exposed to Cd. In addition, the hsp70 and hsp90 genes were also evaluated after heat shock treatment. Real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis showed that Cd presence induced a significant increase in the mRNA levels of ER, ERR and RXR, suggesting a putative mode of action that could explain the endocrine disruptor activity of this heavy metal at the molecular level on Gastropoda. Moreover, the hsp70 gene was upregulated after 24-h Cd treatment, but the hsp90 gene expression was not affected. In contrast, the hsp70 and hsp90 genes were strongly upregulated during heat shock response. Finally, the MT gene expression showed a non-significant variability after Cd exposure. In conclusion, this study provides, for the first time, information about the effects of Cd on the endocrine system of Gastropoda at the molecular level and offers new putative biomarker genes that could be useful in ecotoxicological studies, risk assessment and bioremediation.