Hsp70B' regulation and function

Skin transcriptomic analysis reveals candidate genes and pathways associated with thermotolerance in hair sheep

The skin plays an important role in thermoregulation. Identification of genes on the skin that contribute to increased heat tolerance can be used to select animals with the best performance in warm environments. Our objective was to identify candidate genes associated with the heat stress response in the skin of Santa Ines sheep. A group of 80 sheep assessed for thermotolerance was kept in a climatic chamber for 8 days at a stress level temperature of 36 °C (10 am to 04 pm) and a maintenance temperature of 28 °C (04 pm to 10 am). Two divergent groups, with seven animals each, were formed after ranking them by thermotolerance using rectal temperature. From skin biopsy samples, total RNA was extracted, quantified, and used for RNA-seq analysis. 15,989 genes were expressed in sheep skin samples, of which 4 genes were differentially expressed (DE; FDR < 0.05) and 11 DE (FDR 0.05-0.177) between the two divergent groups. These genes are involved in cellular protection against stress (HSPA1A and HSPA6), ribosome assembly (28S, 18S, and 5S ribosomal RNA), and immune response (IGHG4, GNLY, CXCL1, CAPN14, and SAA-4). The candidate genes and main pathways related to heat tolerance in Santa Ines sheep require further investigation to understand their response to heat stress in different climatic conditions and under solar radiation. It is essential to verify whether these genes and pathways are present in different breeds and to understand the relationship between heat stress and other genes identified in this study.

Elotuzumab Enhances CD16-Independent NK Cell-Mediated Cytotoxicity against Myeloma Cells by Upregulating Several NK Cell-Enhancing Genes

Multiple myeloma (MM) is an intractable hematological malignancy caused by abnormalities in plasma cells. Combination therapy using antibodies and natural killer (NK) effectors, which are innate immune cells with safe and potent antitumor activity, is a promising approach for cancer immunotherapy and can enhance antitumor effects. Elotuzumab (Elo) is an immune-stimulatory antibody that targets the signaling lymphocytic activation molecule family 7 (SLAMF7) expressed on the surface of MM and NK cells. We confirmed that Elo strongly promoted NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) against SLAMF7-positive MM cells in a CD16-dependent NK cell line, and also activated expanded NK cells derived from peripheral blood mononuclear cells of healthy donors and patients with MM in the present study. However, the antitumor effects and genes involved in the direct promotion of NK cell-mediated activation using Elo in CD16-independent NK cells are not clearly known. In this study, we demonstrated that Elo pretreatment significantly enhanced CD16-independent NK cell-mediated cytotoxicity in both SLAMF7-positive MM.1S and SLAMF7-negative K562, U266, and RPMI 8226 tumor cells. Upon direct simulation of CD16-independent NK cells with Elo, increased levels of CD107a degranulation and IFN-γ secretion were observed along with the upregulation of granzyme B, TNF-α, and IL-1α gene expression. The enhanced NK cell function could also be attributed to the increased expression of the transcription factors T-BET and EOMES. Furthermore, the augmentation of the antitumor effects of CD16-independent NK cells upon pretreatment with Elo enhanced the expression of CRTAM, TNFRSF9, EAT-2, and FOXP3 genes and reduced the expression of HSPA6. Our results suggest that Elo directly promotes the cytotoxic function of CD16-independent NK cells against target cells, which is associated with the upregulation of the expression of several NK cell-enhancing genes.

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.

Exposure to Cis- and Trans-regioisomers of S-(1,2-dichlorovinyl)-L-cysteine and S-(1,2-dichlorovinyl)-glutathione result in quantitatively and qualitatively different cellular effects in RPTEC/TERT1 cells

Bioactivation of trichloroethylene (TCE) via glutathione conjugation is associated with several adverse effects in the kidney and other extrahepatic tissues. Of the three regioisomeric conjugates formed, S-(1,2-trans-dichlorovinyl)-glutathione (1,2-trans-DCVG), S-(1,2-cis-dichlorovinyl)-glutathione and S-(2,2-dichlorovinyl)-glutathione, only 1,2-trans-DCVG and its corresponding cysteine-conjugate, 1,2-trans-DCVC, have been subject to extensive mechanistic studies. In the present study, the metabolism and cellular effects of 1,2-cis-DCVG, the major regioisomer formed by rat liver fractions, and 1,2-cis-DCVC were investigated for the first time using RPTEC/TERT1-cells as in vitro renal model. In contrast to 1,2-trans-DCVG/C, the cis-regioisomers showed minimal effects on cell viability and mitochondrial respiration. Transcriptomics analysis showed that both 1,2-cis-DCVC and 1,2-trans-DCVC caused Nrf2-mediated antioxidant responses, with 3µM as lowest effective concentration. An ATF4-mediated integrated stress response and p53-mediated responses were observed starting from 30µM for 1,2-trans-DCVC and 125µM for 1,2-cis-DCVC. Comparison of the metabolism of the DCVG regioisomers by LC/MS showed comparable rates of processing to their corresponding DCVC. No detectable N-acetylation was observed in RPTEC/TERT1 cells. Instead, N-glutamylation of DCVC to form N-γ-glutamyl-S-(dichlorovinyl)-L-cysteine was identified as a novel route of metabolism. The results suggest that 1,2-cis-DCVC may be of less toxicological concern for humans than 1,2-trans-DCVC, considering its lower intrinsic toxicity and lower rate of formation by human liver fractions.

Cluster of resistance-inducing genes in MCF-7 cells by estrogen, insulin, methotrexate and tamoxifen extracted via NMF

Breast cancer has become a leading cause of death for women as the economy has grown and the number of women in the labor force has increased. Several biomarkers with diagnostic, prognostic, and therapeutic implications for breast cancer have been identified in studies, leading to therapeutic advances. Resistance, on the other hand, is one of clinical practice's limitations. In this paper, we use Nonnegative Matrix Factorization to automatically extract two gene signatures from gene expression profiles of wild-type and resistance MCF-7 cells, which were then investigated further using pathways analysis and proved useful in relating resistance pathways to breast cancer regardless of the stimulus that caused it. A few extracted genes (including MAOA, IL4I1, RRM2, DUT, NME4, and SUMO3) represent new elements in the functional network for resistance in MCF-7 ER+ breast cancer. As a result of this research, a better understanding of how resistance occurs or the pathways that contribute to it may allow more effective therapies to be developed.

Transcriptome-based analysis of early post-mortem formation of pale, soft, and exudative (PSE) pork

Pale, soft, and exudative (PSE) meat can cause consumer dissatisfaction and economic losses. This study determined meat quality, glycolytic enzyme activity, and differential gene expression in the longissimus lumborum (LL) and semimembranosus (SM) of normal and PSE pork carcasses. The SM did not result in PSE meat. Hexokinase, lactate dehydrogenase, and pyruvate kinase activities were lower in the SM of PSE carcasses than in the normal carcasses. Functional enrichment analysis revealed that immune, inflammatory, and muscle fibre genes were significantly enriched in PSE pork. More specifically, PPP1R3G and MSS51 may be key genes regulating pork quality in the SM. Meanwhile, the differential expression of PLVAB, ADIPOQ, LEP, MYH4, MYH7, MYL3, MYL6B, FOS, ATF3, and HSPA6 may induce PSE formation in the LL. These results may provide insights into PSE pork formation mechanisms and reveal candidate genes for improving meat quality after validation.

HSP70 upregulation in nasal mucosa of symptomatic children with allergic rhinitis and potential risk of asthma development

Allergic rhinitis and asthma are the most common causes of chronic inflammation of the upper and lower airways in childhood. However, a nasal biomarker that can link to pulmonary inflammation is yet to be found. The present paper aims to investigate the possible role in inflammation of two inducible 70-kDa Heat Shock Proteins (HSP70) members, HSPA1A/B and HSPA6, in nasal mucosa cells of allergic children through their mRNA expression analysis, and their correlation to both spirometric and FeNO values. The relationship between FeNO in lower airways and ∆Cts of HSPA1A/B in nasal mucosa seems to be influenced by clinical symptoms regardless of age, sex, and sensitization patterns. Therefore, HSP70 expression, as well as FeNO levels, could have a predictive capability to identify lower airways inflammation and thus to recognize rhinitic children having a potential risk of asthma development.

Targeted Analysis of HSP70 Isoforms in Human Spermatozoa in the Context of Capacitation and Motility

HSP70s constitute a family of chaperones, some isoforms of which appear to play a role in sperm function. Notably, global proteomic studies analyzing proteins deregulated in asthenozoospermia, a main cause of male infertility characterized by low sperm motility, showed the dysregulation of some HSP70 isoforms. However, to date, no clear trend has been established since the variations in the abundance of HSP70 isoforms differed between studies. The HSPA2 isoform has been reported to play a key role in fertilization, but its dysregulation and possible relocation during capacitation, a maturation process making the spermatozoon capable of fertilizing an oocyte, is debated in the literature. The aim of the present study was to investigate the fate of all sperm HSP70 isoforms during capacitation and in relation to sperm motility. Using Multiple-Reaction Monitoring (MRM) mass spectrometry, we showed that the relative abundance of all detected isoforms was stable between non-capacitated and capacitated spermatozoa. Immunofluorescence using two different antibodies also demonstrated the stability of HSP70 isoform localization during capacitation. We also investigated spermatozoa purified from 20 sperm samples displaying various levels of total and progressive sperm motility. We showed that the abundance of HSP70 isoforms is not correlated to sperm total or progressive motility.

HSPA6 and its role in cancers and other diseases

Heat Shock Protein Family A (Hsp70) Member 6 (HSPA6) (Online Mendelian Inheritance in Man: 140555) belongs to the HSP70 family and is a partially conserved inducible protein in mammals. The HSPA6 gene locates on the human chromosome 1q23.3 and encodes a protein containing two important structural domains: The N-terminal nucleotide-binding domain and the C-terminal substrate-binding domain. Currently, studies have found that HSPA6 not only plays a role in the tumorigenesis and tumor progresses but also causes non-tumor-related diseases. Furthermore, HSPA6 exhibits to inhibit tumorigenesis and tumor progression in some types of cancers but promotes in others. Even though HSPA6 research has increased, its exact roles and mechanisms are still unclear. This article reviews the structure, expression, function, research progress, possible mechanism, and perspective of HSPA6 in cancers and other diseases, highlighting its potential role as a targeted therapeutic and prognostic marker.

The Inflamm-Aging Model Identifies Key Risk Factors in Atherosclerosis

Background: Atherosclerosis, one of the main threats to human life and health, is driven by abnormal inflammation (i.e., chronic inflammation or oxidative stress) during accelerated aging. Many studies have shown that inflamm-aging exerts a significant impact on the occurrence of atherosclerosis, particularly by inducing an immune homeostasis imbalance. However, the potential mechanism by which inflamm-aging induces atherosclerosis needs to be studied more thoroughly, and there is currently a lack of powerful prediction models.

Methods: First, an improved inflamm-aging prediction model was constructed by integrating aging, inflammation, and disease markers with the help of machine learning methods; then, inflamm-aging scores were calculated. In addition, the causal relationship between aging and disease was identified using Mendelian randomization. A series of risk factors were also identified by causal analysis, sensitivity analysis, and network analysis.

Results: Our results revealed an accelerated inflamm-aging pattern in atherosclerosis and suggested a causal relationship between inflamm-aging and atherosclerosis. Mechanisms involving inflammation, nutritional balance, vascular homeostasis, and oxidative stress were found to be driving factors of atherosclerosis in the context of inflamm-aging.

Conclusion: In summary, we developed a model integrating crucial risk factors in inflamm-aging and atherosclerosis. Our computation pipeline could be used to explore potential mechanisms of related diseases.

Alterations in Proteostasis System Components in Peripheral Blood Mononuclear Cells in Parkinson Disease: Focusing on the HSP70 and p62 Levels

Parkinson disease (PD) is attributed to a proteostasis disorder mediated by α-synuclein accumulating in a specific brain region. PD manifestation is often related to extraneuronal alterations, some of which could be used as diagnostic or prognostic PD biomarkers. In this work, we studied the shifts in the expression of proteostasis-associated chaperones of the HSP70 family and autophagy-dependent p62 protein values in the peripheral blood mononuclear cells (PBMC) of mild to moderate PD patients. Although we did not detect any changes in the intracellular HSP70 protein pool in PD patients compared to non-PD controls, an increase in the transcriptional activity of the stress-associated HSPA1A/B and HSPA6 genes was observed in these cells. Basal p62 content was found to be increased in PD patients’ PBMC, similarly to the p62 level in substantia nigra neural cells in PD. Moreover, the spontaneous apoptosis level was increased among PBMC and positively correlated with the p62 intracellular level in the PD group. A combined HSPA6- and p62-based analysis among 26 PD patients and 36 age-matched non-PD controls pointed out the diagnostic significance of these markers, with intermediate sensitivity and high specificity of this combination when observing patients diagnosed with PD.

Prediction of Mechanosensitive Genes in Vascular Endothelial Cells Under High Wall Shear Stress

Objective: The vulnerability of atherosclerotic plaques is among the leading cause of ischemic stroke. High wall shear stress (WSS) promotes the instability of atherosclerotic plaques by directly imparting mechanical stimuli, but the specific mechanisms remain unclear. We speculate that modulation of mechanosensitive genes may play a vital role in accelerating the development of plaques. The purpose of this study was to find mechanosensitive genes in vascular endothelial cells (ECs) through combining microarray data with bioinformatics technology and further explore the underlying dynamics–related mechanisms that cause the progression and destabilization of atherosclerotic plaques.

Methods: Microarray data sets for human vascular ECs under high and normal WSS were retrieved from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified through the R language. The performance of enrichment analysis and protein–protein interaction (PPI) network presented the biological function and signaling pathways of the DEGs. Hub genes were identified based on the PPI network and validated by GEO data sets. Predicted transcription factor (TF) genes and miRNAs interaction with potential mechanosensitive genes were identified by NetworkAnalyst.

Results: A total of 260 DEGs, 121 upregulated and 139 downregulated genes, were screened between high and normal WSS from GSE23289. A total of 10 hub genes and four cluster modules were filtered out based on the PPI network. The enrichment analysis showed that the biological functions of the hub genes were mainly involved in responses to unfolded protein and topologically incorrect protein, and t to endoplasmic reticulum stress. The significant pathways associated with the hub genes were those of protein processing in the endoplasmic reticulum, antigen processing, and presentation. Three out of the 10 hub genes, namely, activated transcription factor 3 (ATF3), heat shock protein family A (Hsp70) member 6 (HSPA6), and dual specificity phosphatase 1 (DUSP1, also known as CL100, HVH1, MKP-1, PTPN10), were verified in GSE13712. The expression of DUSP1 was higher in the senescent cell under high WSS than that of the young cell. The TF–miRNA–mechanosensitive gene coregulatory network was constructed.

Conclusion: In this work, we identified three hub genes, ATF3, HSPA6, and DUSP1, as the potential mechanosensitive genes in the human blood vessels. DUSP1 was confirmed to be associated with the senescence of vascular ECs. Therefore, these three mechanosensitive genes may have emerged as potential novel targets for the prediction and prevention of ischemic stroke. Furthermore, the TF–miRNA–mechanosensitive genes coregulatory network reveals an underlying regulatory mechanism and the pathways to control disease progression.

Genetically Encoded Protein Thermometer Enables Precise Electrothermal Control of Transgene Expression

Body temperature is maintained at around 37 °C in humans, but may rise to 40 °C or more during high-grade fever, which occurs in most adults who are seriously ill. However, endogenous temperature sensors, such as ion channels and heat-shock promoters, are fully activated only at noxious temperatures above this range, making them unsuitable for medical applications. Here, a genetically encoded protein thermometer (human enhanced gene activation thermometer; HEAT) is designed that can trigger transgene expression in the range of 37-40 °C by linking a mutant coiled-coil temperature-responsive protein sensor to a synthetic transcription factor. To validate the construct, a HEAT-transgenic monoclonal human cell line, FeverSense, is generated and it is confirmed that it works as a fever sensor that can temperature- and exposure-time-dependently trigger reporter gene expression in vitro and in vivo. For translational proof of concept, microencapsulated designer cells stably expressing a HEAT-controlled insulin production cassette in a mouse model of type-1 diabetes are subcutaneously implanted and topical heating patches are used to apply heat corresponding to a warm sensation in humans. Insulin release is induced, restoring normoglycemia. Thus, HEAT appears to be suitable for practical electrothermal control of cell-based therapy, and may also have potential for next-generation treatment of fever-associated medical conditions.

TRIM22 inhibits the proliferation of gastric cancer cells through the Smad2 protein

TRIM22 is involved in tumorigenesis and development, but its mechanism is not clear. In this study, we investigated the expression and biological role of TRIM22 in gastric cancer. We found that TRIM22 mRNA and protein expression was abnormally low in gastric cancer tissues and cells and correlated with tumor size and depth of invasion. Overexpression of TRIM22 significantly inhibited the proliferation, colony formation, and migration of gastric cancer cells and downregulated the expression of HSPA6. However, the HSPA6-siRNA complementation test showed that TRIM22 did not regulate cell proliferation through HSPA6. Furthermore, overexpression of TRIM22 downregulated the phosphorylation of Smad2 and Smad3. In addition, TRIM22 directly binds to Smad2, and overexpression of Smad2 can reverse the inhibition of cell proliferation and migration induced by TRIM22. In vivo, overexpression of TRIM22 significantly inhibited the growth of subcutaneous xenografts in nude mice. Our study indicates that TRIM22 has an important role in the development of gastric cancer and may inhibit the proliferation of gastric cancer cells through Smad2.

FHL-1 interacts with human RPE cells through the α5β1 integrin and confers protection against oxidative stress

Retinal pigment epithelial (RPE) cells that underlie the neurosensory retina are essential for the maintenance of photoreceptor cells and hence vision. Interactions between the RPE and their basement membrane, i.e. the inner layer of Bruch's membrane, are essential for RPE cell health and function, but the signals induced by Bruch's membrane engagement, and their contributions to RPE cell fate determination remain poorly defined. Here, we studied the functional role of the soluble complement regulator and component of Bruch's membrane, Factor H-like protein 1 (FHL-1). Human primary RPE cells adhered to FHL-1 in a manner that was eliminated by either mutagenesis of the integrin-binding RGD motif in FHL-1 or by using competing antibodies directed against the α5 and β1 integrin subunits. These short-term experiments reveal an immediate protein-integrin interaction that were obtained from primary RPE cells and replicated using the hTERT-RPE1 cell line. Separate, longer term experiments utilising RNAseq analysis of hTERT-RPE1 cells bound to FHL-1, showed an increased expression of the heat-shock protein genes HSPA6, CRYAB, HSPA1A and HSPA1B when compared to cells bound to fibronectin (FN) or laminin (LA). Pathway analysis implicated changes in EIF2 signalling, the unfolded protein response, and mineralocorticoid receptor signalling as putative pathways. Subsequent cell survival assays using H2O2 to induce oxidative stress-induced cell death suggest hTERT-RPE1 cells had significantly greater protection when bound to FHL-1 or LA compared to plastic or FN. These data show a non-canonical role of FHL-1 in protecting RPE cells against oxidative stress and identifies a novel interaction that has implications for ocular diseases such as age-related macular degeneration.

Heat Shock Protein A6, a Novel HSP70, Is Induced During Enterovirus A71 Infection to Facilitate Internal Ribosomal Entry Site-Mediated Translation

Enterovirus A71 (EV-A71) is a human pathogen causing hand, foot, and mouth disease (HFMD) in children. Its infection can lead to severe neurological diseases or even death in some cases. While being produced in a large quantity during infection, viral proteins often require the assistance from cellular chaperones for proper folding. In this study, we found that heat shock protein A6 (HSPA6), whose function in viral life cycle is scarcely studied, was induced and functioned as a positive regulator for EV-A71 infection. Depletion of HSPA6 led to the reductions of EV-A71 viral proteins, viral RNA and virions as a result of the downregulation of internal ribosomal entry site (IRES)-mediated translation. Unlike other HSP70 isoforms such as HSPA1, HSPA8, and HSPA9, which regulate all phases of the EV-A71 life, HSPA6 was required for the IRES-mediated translation only. Unexpectedly, the importance of HSPA6 in the IRES activity could be observed in the absence of viral proteins, suggesting that HSPA6 facilitated IRES activity through cellular factor(s) instead of viral proteins. Intriguingly, the knockdown of HSPA6 also caused the reduction of luciferase activity driven by the IRES from coxsackievirus A16, echovirus 9, encephalomyocarditis virus, or hepatitis C virus, supporting that HSPA6 may assist the function of a cellular protein generally required for viral IRES activities.

Validation of exercise-response genes in skeletal muscle cells of Thoroughbred racing horses

Objective

To understand the athletic characteristics of Thoroughbreds, high-throughput analysis has been conducted using horse muscle tissue. However, an in vitro system has been lacking for studying and validating genes from in silico data. The aim of this study is to validate genes from differentially expressed genes (DEGs) of our previous RNA-sequencing data in vitro. Also, we investigated the effects of exercise-induced stress including heat, oxidative, hypoxic and cortisol stress on horse skeletal muscle derived cells with the top six upregulated genes of DEGs.

Methods

Enriched pathway analysis was conducted using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) tool with upregulated genes in horse skeletal muscle tissue after exercise. Among the candidates, the top six genes were analysed through geneMANIA to investigate gene networks. Muscle cells derived from neonatal horse skeletal tissue were maintained and subjected to exercise-related stressors. Transcriptional changes in the top six genes followed by stressors were investigated using qRT-PCR.

Results

The inflammation response pathway was the most commonly upregulated pathway after horse exercise. Under non-cytotoxic conditions of exercise-related stressors, the transcriptional response of the top six genes was different among types of stress. Oxidative stress yielded the most similar expression pattern to DEGs.

Conclusion

Our results indicate that transcriptional change after horse exercise in skeletal muscle tissue strongly relates to stress response. qRT-PCR results showed that stressors contribute differently to the transcriptional regulation. These results would be valuable information to understand horse exercise in the stress aspect.

Intracellular Targeting of Heat Shock Proteins in Differentiated Human Neuronal Cells Following Proteotoxic Stress

HSPA6 (Hsp70B') is an inducible member of the Hsp70 (HSPA) family of heat shock proteins that is present in the human genome and not found in mouse and rat. Hence it is lacking in current animal models of neurodegenerative diseases. To advance knowledge of the little studied HSPA6, differentiated human neuronal SH-SY5Y cells were treated with the proteotoxic stress-inducing agent MG132. A robust induction of HSPA6 was apparent which localized to the periphery of MG132-induced protein aggregates in the neuronal cytoplasm. Components of the protein disaggregation/refolding machine that co-operate with Hsp70 also targeted the periphery of cytoplasmic protein aggregates, including DNAJB1 (Hsp40-1), HSPH1 (Hsp105α), and HSPB1 (Hsp27). These data suggest that HSPA6 is involved in the response of human neuronal cells to proteotoxic stress that is a feature of neurodegenerative diseases which have been characterized as protein misfolding disorders. Constitutively expressed HSPA8 (Hsc70) also localized tothe periphery of cytoplasmic protein aggregates following the treatment of differentiated human neuronal cells with MG132. HSPA8 could provide a rapid response to proteotoxic stress in neuronal cells, circumventing the time required to upregulate inducible Hsps.

Cellular and Molecular Adaptation of Arabian Camel to Heat Stress

To cope with the extreme heat stress and drought of the desert, the Arabian camel (Camelus dromedarius) has developed exceptional physiological and biochemical particularities. Previous reports focused mainly on the physiological features of Arabian camel and neglected its cellular and molecular characteristics. Heat shock proteins are suggested to play a key role in the protein homeostasis and thermotolerance. Therefore, we aim by this review to elucidate the implication of camel HSPs in its physiological adaptation to heat stress and compare them with HSPs in related mammalian species. Correlation of these molecules to the adaptive mechanisms in camel is of special importance to expand our understanding of the overall camel physiology and homeostasis.

Synthesis, characterization and cytotoxicity of boron nitride nanoparticles: emphasis on toxicogenomics

Nanotechnology is increasingly developing area including more than 700 commercial products such as clothing, food preparation, cosmetics, mechanics, electronics and also health industry. People generally contact with nanoparticles by inhaling from air. Thus, it is becoming important issue to understand harmful effects of nanoparticles on human health and prepare risk reports for common nano-sized materials. In this paper, synthesis, characterization and cytotoxicity evaluation of boron nitride (BN) nanoparticles were performed on human primary alveolar epithelial cells (HPAEpiC) since, main exposure to nanoparticles would generally happen through lung via inhalation. Chemically synthetized BN nanoparticles were characterized by using X-ray crystallography, transmission electron microscope, scanning electron microscope and energy-dispersive X-ray spectroscopy techniques. 3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyltetrazolium bromide, neutral red and lactate dehydrogenase release assays were used to analyze cytotoxicity after nanoparticles exposure. Whole genome microarray analysis was used to find out the effects of BN NPs on gene expressions of HPAEpiC cells. Finally, the database for annotation, visualization and integrated discovery analysis was used to reveal relationships between different cellular pathways and nanoparticle exposure. According to cytotoxicity analysis LC₂₀ value for BN nanoparticles was 125.051 mg/L. Microarray results showed that 2159 genes expression change (FC ≥ 2) significantly over 40,000 genes analysis. When the gene pathways were analyzed, it was seemed that BN nanoparticles mostly affect cell cycle, cell-cell interactions, cancer affecting genes and signal transduction. In a conclusion, our results supported for the first time that BN nanoparticles could be used as a safe nanomaterial in both pharmacological and medical applications.

Differential Glycosylation and Modulation of Camel and Human HSP Isoforms in Response to Thermal and Hypoxic Stresses

Increased expression of heat shock proteins (HSPs) following heat stress or other stress conditions is a common physiological response in almost all living organisms. Modification of cytosolic proteins including HSPs by O-GlcNAc has been shown to enhance their capabilities for counteracting lethal levels of cellular stress. Since HSPs are key players in stress resistance and protein homeostasis, we aimed to analyze their forms at the cellular and molecular level using camel and human HSPs as models for efficient and moderate thermotolerant mammals, respectively. In this study, we cloned the cDNA encoding two inducible HSP members, HSPA6 and CRYAB from both camel (Camelus dromedarius) and human in a Myc-tagged mammalian expression vector. Expression of these chaperones in COS-1 cells revealed protein bands of approximately 25-kDa for both camel and human CRYAB and 70-kDa for camel HSPA6 and its human homologue. While localization and trafficking of the camel and human HSPs revealed similar cytosolic localization, we could demonstrate altered glycan structure between camel and human HSPA6. Interestingly, the glycoform of camel HSPA6 was rapidly formed and stabilized under normal and stress culture conditions whereas human HSPA6 reacted differently under similar thermal and hypoxic stress conditions. Our data suggest that efficient glycosylation of camel HSPA6 is among the mechanisms that provide camelids with a superior capability for alleviating stressful environmental circumstances.

Knockdown of Heat Shock Proteins HSPA6 (Hsp70B') and HSPA1A (Hsp70-1) Sensitizes Differentiated Human Neuronal Cells to Cellular Stress

Heat shock proteins are involved in cellular repair and protective mechanisms that counter characteristic features of neurodegenerative diseases such as protein misfolding and aggregation. The HSPA (Hsp70) multigene family includes the widely studied HSPA1A (Hsp70-1) and the little studied HSPA6 (Hsp70B') which is present in the human genome and not in mouse and rat. The effect of knockdown of HSPA6 and HSPA1A expression was examined in relation to the ability of differentiated human SH-SY5Y neuronal cells to tolerate thermal stress. Low dose co-application of celastrol and arimoclomol, which induces Hsps, enhanced the ability of differentiated neurons to survive heat shock. Small interfering RNA (siRNA) knockdown of HSPA6 and HSPA1A resulted in loss of the protective effect of co-application of celastrol/arimoclomol. More pronounced effects on neuronal viability were apparent at 44 °C heat shock compared to 43 °C. siRNA knockdown suggests that HSPA6 and HSPA1A contribute to protection of differentiated human neuronal cells from cellular stress.

Differential Targeting of Hsp70 Heat Shock Proteins HSPA6 and HSPA1A with Components of a Protein Disaggregation/Refolding Machine in Differentiated Human Neuronal Cells following Thermal Stress

Heat shock proteins (Hsps) co-operate in multi-protein machines that counter protein misfolding and aggregation and involve DNAJ (Hsp40), HSPA (Hsp70), and HSPH (Hsp105α). The HSPA family is a multigene family composed of inducible and constitutively expressed members. Inducible HSPA6 (Hsp70B') is found in the human genome but not in the genomes of mouse and rat. To advance knowledge of this little studied HSPA member, the targeting of HSPA6 to stress-sensitive neuronal sites with components of a disaggregation/refolding machine was investigated following thermal stress. HSPA6 targeted the periphery of nuclear speckles (perispeckles) that have been characterized as sites of transcription. However, HSPA6 did not co-localize at perispeckles with DNAJB1 (Hsp40-1) or HSPH1 (Hsp105α). At 3 h after heat shock, HSPA6 co-localized with these members of the disaggregation/refolding machine at the granular component (GC) of the nucleolus. Inducible HSPA1A (Hsp70-1) and constitutively expressed HSPA8 (Hsc70) co-localized at nuclear speckles with components of the machine immediately after heat shock, and at the GC layer of the nucleolus at 1 h with DNAJA1 and BAG-1. These results suggest that HSPA6 exhibits targeting features that are not apparent for HSPA1A and HSPA8.

HSPA6 augments garlic extract-induced inhibition of proliferation, migration, and invasion of bladder cancer EJ cells; Implication for cell cycle dysregulation, signaling pathway alteration, and transcription factor-associated MMP-9 regulation

Although recent studies have demonstrated the anti-tumor effects of garlic extract (GE), the exact molecular mechanism is still unclear. In this study, we investigated the molecular mechanism associated with the inhibitory action of GE against bladder cancer EJ cell responses. Treatment with GE significantly inhibited proliferation of EJ cells dose-dependently through G₂/M-phase cell cycle arrest. This G₂/M-phase cell cycle arrest by GE was due to the activation of ATM and CHK2, which appears to inhibit phosphorylation of Cdc25C (Ser216) and Cdc2 (Thr14/Tyr15), this in turn was accompanied by down-regulation of cyclin B1 and up-regulation of p21WAF1. Furthermore, GE treatment was also found to induce phosphorylation of MAPK (ERK1/2, p38MAPK, and JNK) and AKT. In addition, GE impeded the migration and invasion of EJ cells via inhibition of MMP-9 expression followed by decreased binding activities of AP-1, Sp-1, and NF-κB motifs. Based on microarray datasets, we selected Heat shock protein A6 (HSPA6) as the most up-regulated gene responsible for the inhibitory effects of GE. Interestingly, overexpression of HSPA6 gene resulted in an augmentation effect with GE inhibiting proliferation, migration, and invasion of EJ cells. The augmentation effect of HSPA6 was verified by enhancing the induction of G₂/M-phase-mediated ATM-CHK2-Cdc25C-p21WAF1-Cdc2 cascade, phosphorylation of MAPK and AKT signaling, and suppression of transcription factor-associated MMP-9 regulation in response to GE in EJ cells. Overall, our novel results indicate that HSPA6 reinforces the GE-mediated inhibitory effects of proliferation, migration, and invasion of EJ cells and may provide a new approach for therapeutic treatment of malignancies.

HSP70 in human polymorphonuclear and mononuclear leukocytes: comparison of the protein content and transcriptional activity of HSPA genes

Cell-type specific variations are typical for the expression of different members of the HSP70 family. In circulating immune cells, HSP70 proteins interact with units of signaling pathways involved in the immune responses and may promote cell survival in sites of inflammation. In this work, we compared basal HSP70 expression and stress-induced HSP70 response in polymorphonuclear and mononuclear human leukocytes. The intracellular content of inducible and constitutive forms of HSP70 was analyzed in relation to the transcriptional activity of HSPA genes. Hyperthermia was used as the stress model for induction of HSP70 synthesis in the cells. Our results demonstrated that granulocytes (mainly neutrophils) and mononuclear cells differ significantly by both basal HSP70 expression and levels of HSP70 induction under hyperthermia. The differences were observed at the levels of HSPA gene transcription and intracellular HSP70 content. The expression of constitutive Hsс70 protein was much higher in mononuclear cells consisting of monocytes and lymphocytes than in granulocytes. At the same time, intact neutrophils showed increased expression of inducible Hsp70 protein compared to mononuclear cells. Heat treatment induced additional expression of HSPA genes in leukocytes. The most pronounced increase in the expression was observed in polymorphonuclear and mononuclear leukocytes for HSPA1A/B. However, in granulocytes, the induction of the transcription of the HSPA8 gene encoding the Hsc70 protein was significantly higher than in mononuclear cells. These variations in transcriptional activity of HSPA genes and intracellular HSP70 content in different populations of leukocytes may reflect specified requirements for the chaperone activity in the cells with a distinct functional role in the immune system.

The human RHOX gene cluster: target genes and functional analysis of gene variants in infertile men

The X-linked reproductive homeobox (RHOX) gene cluster encodes transcription factors preferentially expressed in reproductive tissues. This gene cluster has important roles in male fertility based on phenotypic defects of Rhox-mutant mice and the finding that aberrant RHOX promoter methylation is strongly associated with abnormal human sperm parameters. However, little is known about the molecular mechanism of RHOX function in humans. Using gene expression profiling, we identified genes regulated by members of the human RHOX gene cluster. Some genes were uniquely regulated by RHOXF1 or RHOXF2/2B, while others were regulated by both of these transcription factors. Several of these regulated genes encode proteins involved in processes relevant to spermatogenesis; e.g. stress protection and cell survival. One of the target genes of RHOXF2/2B is RHOXF1, suggesting cross-regulation to enhance transcriptional responses. The potential role of RHOX in human infertility was addressed by sequencing all RHOX exons in a group of 250 patients with severe oligozoospermia. This revealed two mutations in RHOXF1 (c.515G > A and c.522C > T) and four in RHOXF2/2B (-73C > G, c.202G > A, c.411C > T and c.679G > A), of which only one (c.202G > A) was found in a control group of men with normal sperm concentration. Functional analysis demonstrated that c.202G > A and c.679G > A significantly impaired the ability of RHOXF2/2B to regulate downstream genes. Molecular modelling suggested that these mutations alter RHOXF2/F2B protein conformation. By combining clinical data with in vitro functional analysis, we demonstrate how the X-linked RHOX gene cluster may function in normal human spermatogenesis and we provide evidence that it is impaired in human male fertility.

Dynamics of the association of heat shock protein HSPA6 (Hsp70B') and HSPA1A (Hsp70-1) with stress-sensitive cytoplasmic and nuclear structures in differentiated human neuronal cells

Heat shock proteins (Hsps) are cellular repair agents that counter the effects of protein misfolding that is a characteristic feature of neurodegenerative diseases. HSPA1A (Hsp70-1) is a widely studied member of the HSPA (Hsp70) family. The little-studied HSPA6 (Hsp70B') is present in the human genome and absent in mouse and rat; hence, it is missing in current animal models of neurodegenerative diseases. Differentiated human neuronal SH-SY5Y cells were employed to compare the dynamics of the association of YFP-tagged HSPA6 and HSPA1A with stress-sensitive cytoplasmic and nuclear structures. Following thermal stress, live-imaging confocal microscopy and Fluorescence Recovery After Photobleaching (FRAP) demonstrated that HSPA6 displayed a prolonged and more dynamic association, compared to HSPA1A, with centrioles that play critical roles in neuronal polarity and migration. HSPA6 and HSPA1A also targeted nuclear speckles, rich in RNA splicing factors, and the granular component of the nucleolus that is involved in rRNA processing and ribosomal subunit assembly. HSPA6 and HSPA1A displayed similar FRAP kinetics in their interaction with nuclear speckles and the nucleolus. Subsequently, during the recovery from neuronal stress, HSPA6, but not HSPA1A, localized with the periphery of nuclear speckles (perispeckles) that have been characterized as transcription sites. The stress-induced association of HSPA6 with perispeckles displayed the greatest dynamism compared to the interaction of HSPA6 or HSPA1A with other stress-sensitive cytoplasmic and nuclear structures. This suggests involvement of HSPA6 in transcriptional recovery of human neurons from cellular stress that is not apparent for HSPA1A.

Induction of heat shock proteins in differentiated human neuronal cells following co-application of celastrol and arimoclomol

Few effective therapies exist for the treatment of neurodegenerative diseases that have been characterized as protein misfolding disorders. Upregulation of heat shock proteins (Hsps) mitigates against the accumulation of misfolded, aggregation-prone proteins and synaptic dysfunction, which is recognized as an early event in neurodegenerative diseases. Enhanced induction of a set of Hsps in differentiated human SH-SY5Y neuronal cells was observed following co-application of celastrol and arimoclomol, compared to their individual application. The dosages employed did not affect cell viability or neuronal process morphology. The induced Hsps included the little studied HSPA6 (Hsp70B'), a potentially neuroprotective protein that is present in the human genome but not in rat and mouse and hence is missing in current animal models of neurodegenerative disease. Enhanced induction of HSPA1A (Hsp70-1), DNAJB1 (Hsp40), HO-1 (Hsp32), and HSPB1 (Hsp27) was also observed. Celastrol activates heat shock transcription factor 1 (HSF1), the master regulator of Hsp gene transcription, and also exhibits potent anti-inflammatory and anti-oxidant activities. Arimoclomol is a co-activator that prolongs the binding of activated HSF1 to heat shock elements (HSEs) in the promoter regions of inducible Hsp genes. Elevated Hsp levels peaked at 10 to 12 h for HSPA6, HSPA1A, DNAJB1, and HO-1 and at 24 h for HSPB1. Co-application of celastrol and arimoclomol induced higher Hsp levels compared to heat shock paired with arimoclomol. The co-application strategy of celastrol and arimoclomol targets multiple neurodegenerative disease-associated pathologies including protein misfolding and protein aggregation, inflammatory and oxidative stress, and synaptic dysfunction.

Heat Shock 70 Protein Genes and Genetic Susceptibility to Apical Periodontitis

INTRODUCTION

Heat shock proteins (HSPs) protect cells under adverse conditions such as infection, inflammation, and disease. The differential expression of HSPs in human periapical granulomas suggests a potential role for these proteins in periapical lesion development, which may contribute to different clinical outcomes. Therefore, we hypothesized that polymorphisms in HSP genes leading to perturbed gene expression and protein function may contribute to an individual's susceptibility to periapical lesion development.

METHODS

Subjects with deep carious lesions with or without periapical lesions (≥3 mm) were recruited at the University of Texas School of Dentistry at Houston and at the University of Pittsburgh. Genomic DNA samples of 400 patients were sorted into 2 groups: 183 cases with deep carious lesions and periapical lesions (cases) and 217 cases with deep carious lesions but without periapical lesions (controls). Eight single nucleotide polymorphisms (SNPs) in HSPA4, HSPA6, HSPA1L, HSPA4L, and HSPA9 genes were selected for genotyping. Genotypes were generated by end point analysis by using Taqman chemistry in a real-time polymerase chain reaction assay. Allele and genotype frequencies were compared among cases and controls by using χ(2) and Fisher exact tests as implemented in PLINK v.1.07. In silico analysis of SNP function was performed by using Polymorphism Phenotyping V2 and MirSNP software.

RESULTS

Overall, SNPs in HSPA1L and HSPA6 showed significant allelic association with cases of deep caries and periapical lesions (P < .05). We also observed altered transmission of HSPA1L SNP haplotypes (P = .03). In silico analysis of HSPA1L rs2075800 function showed that this SNP results in a glutamine-to-lysine substitution at position 602 of the protein and might affect the stability and function of the final protein.

CONCLUSIONS

Variations in HSPA1L and HSPA6 may be associated with periapical lesion formation in individuals with untreated deep carious lesions. Future studies could help predict host susceptibility to developing apical periodontitis.

Chaperones in hepatitis C virus infection

The hepatitis C virus (HCV) infects approximately 3% of the world population or more than 185 million people worldwide. Each year, an estimated 350000-500000 deaths occur worldwide due to HCV-associated diseases including cirrhosis and hepatocellular carcinoma. HCV is the most common indication for liver transplantation in patients with cirrhosis worldwide. HCV is an enveloped RNA virus classified in the genus Hepacivirus in the Flaviviridae family. The HCV viral life cycle in a cell can be divided into six phases: (1) binding and internalization; (2) cytoplasmic release and uncoating; (3) viral polyprotein translation and processing; (4) RNA genome replication; (5) encapsidation (packaging) and assembly; and (6) virus morphogenesis (maturation) and secretion. Many host factors are involved in the HCV life cycle. Chaperones are an important group of host cytoprotective molecules that coordinate numerous cellular processes including protein folding, multimeric protein assembly, protein trafficking, and protein degradation. All phases of the viral life cycle require chaperone activity and the interaction of viral proteins with chaperones. This review will present our current knowledge and understanding of the role of chaperones in the HCV life cycle. Analysis of chaperones in HCV infection will provide further insights into viral/host interactions and potential therapeutic targets for both HCV and other viruses.

Endothelial nitric oxide synthase induces heat shock protein HSPA6 (HSP70B') in human arterial smooth muscle cells

Endothelial nitric oxide synthase (eNOS) is the major source of nitric oxide (NO) production in blood vessels. One of the pleitropic functions of eNOS derived NO is to inhibit vascular smooth muscle cell proliferation in the blood vessel wall, and whose dysfunction is a primary cause of atherosclerosis and restenosis. In this study there was an interest in examining the gene profile of eNOS adenoviral (Ad-eNOS) transduced human coronary artery smooth muscle cells (HCASMC) to further understand the eNOS inhibitory effect on smooth muscle cell proliferation. To this aim a whole genome wide analysis of eNOS transduced HCASMCs was performed. A total of 19 genes were up regulated, and 31 genes down regulated in Ad-eNOS transduced HCASMCs compared to cells treated with an empty adenovirus. Noticeably, a cluster of HSP70 gene family members was amongst the genes up regulated. Quantitative PCR confirmed that transcripts for HSPA1A (HSP70A), HSPA1B (HSP70B) and HSPA6 (HSP70B') were elevated 2, 1.7 and 14-fold respectively in Ad-eNOS treated cells. The novel gene HSPA6 was further explored as a potential mediator of eNOS signaling in HCASMC. Immunoblotting showed that HSPA6 protein was induced by Ade-NOS. To functionally examine the effect of HSPA6 on SMCs, an adenovirus harboring the HSPA6 gene under the control of a constitutive promoter was generated. Transduction of HCASMCs with Ad-HSPA6 inhibited SMC proliferation at 3 and 6 days post serum growth stimulation, and paralleled the Ad-eNOS inhibition of SMC growth. The identification in this study that HSPA6 overexpression inhibits SMC proliferation coupled with the recent finding that inhibition of HSP90 has a similar effect, progresses the field of targeting HSPs for vascular repair.

Optimization of expression and purification of HSPA6 protein from Camelus dromedarius in E. coli

The HSPA6, one of the members of large family of HSP70, is significantly up-regulated and has been targeted as a biomarker of cellular stress in several studies. Herein, conditions were optimized to increase the yield of recombinant camel HSPA6 protein in its native state, primarily focusing on the optimization of upstream processing parameters that lead to an increase in the specific as well as volumetric yield of the protein. The results showed that the production of cHSPA6 was increased proportionally with increased incubation temperature up to 37 °C. Induction with 10 μM IPTG was sufficient to induce the expression of cHSPA6 which was 100 times less than normally used IPTG concentration. Furthermore, the results indicate that induction during early to late exponential phase produced relatively high levels of cHSPA6 in soluble form. In addition, 5 h of post-induction incubation was found to be optimal to produce folded cHSPA6 with higher specific and volumetric yield. Subsequently, highly pure and homogenous cHSPA6 preparation was obtained using metal affinity and size exclusion chromatography. Taken together, the results showed successful production of electrophoretically pure recombinant HSPA6 protein from Camelus dromedarius in Escherichia coli in milligram quantities from shake flask liquid culture.

Regulation of translation factor EEF1D gene function by alternative splicing

Alternative splicing is an exquisite mechanism that allows one coding gene to have multiple functions. The alternative splicing machinery is necessary for proper development, differentiation and stress responses in a variety of organisms, and disruption of this machinery is often implicated in human diseases. Previously, we discovered a long form of eukaryotic elongation factor 1Bδ (eEF1Bδ; this long-form eEF1Bδ results from alternative splicing of EEF1D transcripts and regulates the cellular stress response by transcriptional activation, not translational enhancement, of heat-shock responsive genes. In this review, we discuss the molecular function of EEF1D alternative splicing products and the estimated implication of human diseases.

Basal and stress-inducible expression of HSPA6 in human keratinocytes is regulated by negative and positive promoter regions

Epidermal keratinocytes serve as the primary barrier between the body and environmental stressors. They are subjected to numerous stress events and are likely to respond with a repertoire of heat shock proteins (HSPs). HSPA6 (HSP70B') is described in other cell types with characteristically low to undetectable basal expression, but is highly stress induced. Despite this response in other cells, little is known about its control in keratinocytes. We examined endogenous human keratinocyte HSPA6 expression and localized some responsible transcription factor sites in a cloned HSPA6 3 kb promoter. Using promoter 5' truncations and deletions, negative and positive regulatory regions were found throughout the 3 kb promoter. A region between -346 and -217 bp was found to be crucial to HSPA6 basal expression and stress inducibility. Site-specific mutations and DNA-binding studies show that a previously uncharacterized AP1 site contributes to the basal expression and maximal stress induction of HSPA6. Additionally, a new heat shock element (HSE) within this region was defined. While this element mediates increased transcriptional response in thermally stressed HaCaT keratinocytes, it preferentially binds a stress-inducible factor other than heat shock factor (HSF)1 or HSF2. Intriguingly, this newly characterized HSPA6 HSE competes HSF1 binding a consensus HSE and binds both HSF1 and HSF2 from other epithelial cells. Taken together, our results demonstrate that the HSPA6 promoter contains essential negative and positive promoter regions and newly identified transcription factor targets, which are key to the basal and stress-inducible expression of HSPA6. Furthermore, these results suggest that an HSF-like factor may preferentially bind this newly identified HSPA6 HSE in HaCaT cells.

Induction of tumor cell apoptosis by a proteasome deubiquitinase inhibitor is associated with oxidative stress

AIMS

b-AP15 is a recently described inhibitor of the USP14/UCHL5 deubiquitinases (DUBs) of the 19S proteasome. Exposure to b-AP15 results in blocking of proteasome function and accumulation of polyubiquitinated protein substrates in cells. This novel mechanism of proteasome inhibition may potentially be exploited for cancer therapy, in particular for treatment of malignancies resistant to currently used proteasome inhibitors. The aim of the present study was to characterize the cellular response to b-AP15-mediated proteasome DUB inhibition.

RESULTS

We report that b-AP15 elicits a similar, but yet distinct, cellular response as the clinically used proteasome inhibitor bortezomib. b-AP15 induces a rapid apoptotic response, associated with enhanced induction of oxidative stress and rapid activation of Jun-N-terminal kinase 1/2 (JNK)/activating protein-1 signaling. Scavenging of reactive oxygen species and pharmacological inhibition of JNK reduced b-AP15-induced apoptosis. We further report that endoplasmic reticulum (ER) stress is induced by b-AP15 and is involved in apoptosis induction. In contrast to bortezomib, ER stress is associated with induction of α-subunit of eukaryotic initiation factor 2 phosphorylation.

INNOVATION

The findings establish that different modes of proteasome inhibition result in distinct cellular responses, a finding of potential therapeutic importance.

CONCLUSION

Our data show that enhanced oxidative stress and ER stress are major determinants of the strong apoptotic response elicited by the 19S DUB inhibitor b-AP15.

TNIP1 reduction of HSPA6 gene expression occurs in promoter regions lacking binding sites for known TNIP1-repressed transcription factors

TNFα-induced protein 3-interacting protein 1 (TNIP1) represses signaling pathways initiated by specific nuclear and transmembrane receptors. This effect results in reduced activity of distinct transcription factors such as retinoic acid receptors (RAR), peroxisome-proliferator-activated receptors (PPAR), and NFκB. TNIP1-null and TNIP1-knockin defective for ubiquitin-binding mice show increased liver apoptosis, and enlarged spleen and lymph nodes, respectively. To complement current knowledge of TNIP1's broad physiologic functions as interpreted from in vivo studies and specific expression consequences from transcription factor repression, we determined effects of excess TNIP1 on global gene regulation. Following experimentally increased expression of TNIP1 in cultured keratinocytes, our gene expression microarray analysis not only confirmed TNIP1's association in previously known pathways and functions but also found a novel TNIP1-regulated pathway - the cell stress response. Under standard culture conditions, expression of several heat shock proteins, including HSPA1A, HSPA6, DNAJA1 and DNAJB1, was reduced. In heat-stressed conditions, differential regulation of HSPA1A and HSPA6 was observed, where only HSPA6 expression was reduced after heat-shock. Using HSPA6 as a model to elucidate the mechanism of the TNIP1-mediated HSP repression, we determined that TNIP1 likely represses HSPs through factors other than RAR, PPAR or NFκB despite the presence of these factors' binding sites in the HSPA6 promoter. These results indicate that regulation of HSPs may be through a yet unknown TNIP1-associated pathway. Additionally, these results suggest that TNIP1's reduction of HSP expression levels could negatively impact HSP chaperone capacity or their participation in the cell stress response.

Analysis of gene expression in induced pluripotent stem cell-derived human neurons exposed to botulinum neurotoxin A subtype 1 and a type A atoxic derivative

Botulinum neurotoxin type A1 (BoNT/A1) is a potent protein toxin responsible for the potentially fatal human illness botulism. Notwithstanding, the long-lasting flaccid muscle paralysis caused by BoNT/A has led to its utility as a powerful and versatile bio-pharmaceutical. The flaccid paralysis is due to specific cleavage of neuronal SNAREs by BoNTs. However, actions of BoNTs on intoxicated neurons besides the cleavage of SNAREs have not been studied in detail. In this study we investigated by microarray analysis the effects of BoNT/A and a catalytically inactive derivative (BoNT/A ad) on the transcriptome of human induced pluripotent stem cell (hiPSC)-derived neurons at 2 days and 2 weeks after exposure. While there were only minor changes in expression levels at 2 days post exposure, at 2 weeks post exposure 492 genes were differentially expressed more than 2-fold in BoNT/A1-exposed cells when compared to non-exposed populations, and 682 genes were differentially expressed in BoNT/A ad-exposed cells. The vast majority of genes were similarly regulated in BoNT/A1 and BoNT/A ad-exposed neurons, and the few genes differentially regulated between BoNT/A1 and BoNT/A ad-exposed neurons were differentially expressed less than 3.5 fold. These data indicate a similar response of neurons to BoNT/A1 and BoNT/A ad exposure. The most highly regulated genes in cells exposed to either BoNT/A1 or BoNT/A ad are involved in neurite outgrowth and calcium channel sensitization.

Stress-induced localization of HSPA6 (HSP70B') and HSPA1A (HSP70-1) proteins to centrioles in human neuronal cells

The localization of yellow fluorescent protein (YFP)-tagged HSP70 proteins was employed to identify stress-sensitive sites in human neurons following temperature elevation. Stable lines of human SH-SY5Y neuronal cells were established that expressed YFP-tagged protein products of the human inducible HSP70 genes HSPA6 (HSP70B') and HSPA1A (HSP70-1). Following a brief period of thermal stress, YFP-tagged HSPA6 and HSPA1A rapidly appeared at centrioles in the cytoplasm of human neuronal cells, with HSPA6 demonstrating a more prolonged signal compared to HSPA1A. Each centriole is composed of a distal end and a proximal end, the latter linking the centriole doublet. The YFP-tagged HSP70 proteins targeted the proximal end of centrioles (identified by γ-tubulin marker) rather than the distal end (centrin marker). Centrioles play key roles in cellular polarity and migration during neuronal differentiation. The proximal end of the centriole, which is involved in centriole stabilization, may be stress-sensitive in post-mitotic, differentiating human neurons.

Identification of an inhibitor of the ubiquitin–proteasome system that induces accumulation of polyubiquitinated proteins in the absence of blocking of proteasome function

The ubiquitin–proteasome system (UPS) represents one of the most promising therapeutic targets in oncology to emerge in recent years.

Interference of CuO nanoparticles with metal homeostasis in hepatocytes under sub-toxic conditions

Copper oxide nanoparticles (CuO-NP) were studied for their toxicity and mechanism of action on hepatocytes (HepG2), in relation to Cu homeostasis disruption. Indeed, hepatocytes, in the liver, are responsible for the whole body Cu balance and should be a major line of defence in the case of exposure to CuO-NP. We investigated the early responses to sub-toxic doses of CuO-NP and compared them to equivalent doses of Cu added as salt to see if there is a specific nano-effect related to Cu homeostasis in hepatocytes. The expression of the genes encoding the Cu-ATPase ATP7B, metallothionein 1X, heme oxygenase 1, heat shock protein 70, superoxide dismutase 1, glutamate cysteine ligase modifier subunit, metal responsive element-binding transcription factor 1 and zinc transporter 1 was analyzed by qRT-PCR. These genes are known to be involved in response to Cu, Zn and/or oxidative stresses. Except for MTF1, ATP7B and SOD1, we clearly observed an up regulation of these genes expression in CuO-NP treated cells, as compared to CuCl2. In addition, ATP7B trafficking from the Golgi network to the bile canaliculus membrane was observed in WIF-B9 cells, showing a need for Cu detoxification. This shows an increase in the intracellular Cu concentration, probably due to Cu release from endosomal CuO-NP solubilisation. Our data show that CuO-NP enter hepatic cells, most probably by endocytosis, bypassing the cellular defence mechanism against Cu, thus acting as a Trojan horse. Altogether, this study suggests that sub-toxic CuO-NP treatments induce successively a Cu overload, a Cu-Zn exchange on metallothioneins and MTF1 regulation on both Cu and Zn homeostasis.

HSPA8/HSC70 chaperone protein: structure, function, and chemical targeting

HSPA8/HSC70 protein is a fascinating chaperone protein. It represents a constitutively expressed, cognate protein of the HSP70 family, which is central in many cellular processes. In particular, its regulatory role in autophagy is decisive. We focused this review on HSC70 structure-function considerations and based on this, we put a particular emphasis on HSC70 targeting by small molecules and peptides in order to develop intervention strategies that deviate some of HSC70 properties for therapeutic purposes. Generating active biomolecules regulating autophagy via its effect on HSC70 can effectively be designed only if we understand the fine relationships between HSC70 structure and functions.

Photocoagulation of human retinal pigment epithelial cells in vitro: evaluation of necrosis, apoptosis, cell migration, cell proliferation and expression of tissue repairing and cytoprotective genes

Aims

Sight-threatening diabetic retinopathy has been treated with photocoagulation for decades but the mechanisms behind the beneficial clinical effects are poorly understood. One target of irradiation and a potential player in this process is the retinal pigment epithelium (RPE). Here we establish an in vitro model for photocoagulation of human RPE cells.

Methods

ARPE-19 cells were exposed to photocoagulation and studied at various time points up to 168h. Lesion morphology, necrosis and apoptosis were investigated by light microscopy; LIVE/DEAD staining and measurements of lactate dehydrogenase activity; and TUNEL- and ELISA-based quantification of DNA fragments, respectively. Cell migration and proliferation were explored using docetaxel and mitomycin C; temporal and spatial changes in proliferation were assessed by confocal immunofluorescence of proliferating cell nuclear antigen. Gene expression was measured by qPCR.

Results

Photocoagulation of ARPE-19 resulted in denaturation of proteins and reproducible lesion formation. A transient peak in necrosis, followed by a peak in apoptosis was observed in cells within the lesions at 6h and 24h, respectively after photocoagulation. Cell proliferation was depressed during the first hours after photocoagulation, back to control levels at 24h and augmented in the following days. These effects were not limited to cells in the lesions, but also evident in neighbouring cells. Changes in cell proliferation during lesion repair were preceded by changes in cell migration. Altered mRNA expression of genes previously implicated in the regulation of cell proliferation (FOS, IL-1β, IL-8, HMGA2), migration and tissue repairing (TGFBR2, ADAMTS6, TIMP3, CTGF) was observed, as well as increased expression of the alarmin IL33 and the cytoprotective gene HSPA6.

Conclusions

Using a laser system and experimental settings that comply with standards used in clinical practice, we have established a suitable model for in vitro photocoagulation of human RPE cells to isolate their contribution to the beneficial effects of laser treatment.

Basal and stress-induced Hsp70 are modulated by ataxin-3

Regulation of basal and induced levels of hsp70 is critical for cellular homeostasis. Ataxin-3 is a deubiquitinase with several cellular functions including transcriptional regulation and maintenance of protein homeostasis. While investigating potential roles of ataxin-3 in response to cellular stress, it appeared that ataxin-3 regulated hsp70. Basal levels of hsp70 were lower in ataxin-3 knockout (KO) mouse brain from 2 to 63 weeks of age and hsp70 was also lower in fibroblasts from ataxin-3 KO mice. Transfecting KO cells with ataxin-3 rescued basal levels of hsp70 protein. Western blots of representative chaperones including hsp110, hsp90, hsp70, hsc70, hsp60, hsp40/hdj2, and hsp25 indicated that only hsp70 was appreciably altered in KO fibroblasts and KO mouse brain. Turnover of hsp70 protein was similar in wild-type (WT) and KO cells; however, basal hsp70 promoter reporter activity was decreased in ataxin-3 KO cells. Transfecting ataxin-3 restored hsp70 basal promoter activity in KO fibroblasts to levels of promoter activity in WT cells; however, mutations that inactivated deubiquitinase activity or the ubiquitin interacting motifs did not restore full activity to hsp70 basal promoter activity. Hsp70 protein and promoter activity were higher in WT compared to KO cells exposed to heat shock and azetidine-2-carboxylic acid, but WT and KO cells had similar levels in response to cadmium. Heat shock factor-1 had decreased levels and increased turnover in ataxin-3 KO fibroblasts. Data in this study are consistent with ataxin-3 regulating basal level of hsp70 as well as modulating hsp70 in response to a subset of cellular stresses.

The effects of oxidative stress on female reproduction: a review

Oxidative stress (OS), a state characterized by an imbalance between pro-oxidant molecules including reactive oxygen and nitrogen species, and antioxidant defenses, has been identified to play a key role in the pathogenesis of subfertility in both males and females. The adverse effects of OS on sperm quality and functions have been well documented. In females, on the other hand, the impact of OS on oocytes and reproductive functions remains unclear. This imbalance between pro-oxidants and antioxidants can lead to a number of reproductive diseases such as endometriosis, polycystic ovary syndrome (PCOS), and unexplained infertility. Pregnancy complications such as spontaneous abortion, recurrent pregnancy loss, and preeclampsia, can also develop in response to OS. Studies have shown that extremes of body weight and lifestyle factors such as cigarette smoking, alcohol use, and recreational drug use can promote excess free radical production, which could affect fertility. Exposures to environmental pollutants are of increasing concern, as they too have been found to trigger oxidative states, possibly contributing to female infertility. This article will review the currently available literature on the roles of reactive species and OS in both normal and abnormal reproductive physiological processes. Antioxidant supplementation may be effective in controlling the production of ROS and continues to be explored as a potential strategy to overcome reproductive disorders associated with infertility. However, investigations conducted to date have been through animal or in vitro studies, which have produced largely conflicting results. The impact of OS on assisted reproductive techniques (ART) will be addressed, in addition to the possible benefits of antioxidant supplementation of ART culture media to increase the likelihood for ART success. Future randomized controlled clinical trials on humans are necessary to elucidate the precise mechanisms through which OS affects female reproductive abilities, and will facilitate further explorations of the possible benefits of antioxidants to treat infertility.