Heat shock proteins and DNA repair mechanisms: an updated overview

Characterization and functional analysis of Cshsp19.0 encoding a small heat shock protein in Chilo suppressalis (Walker)

Small heat shock proteins (sHSPs) function as ATP-independent chaperones that preserve cellular proteostasis under stressful conditions. In this study, Cshsp19.0, which encodes a new small heat shock protein, was isolated and characterized from Chilo suppressalis (Walker) to better understand the contribution of sHSPs to insect development and stress tolerance. The full-length Cshsp19.0 cDNA was 697 bp and encoded a 19.0 kDa protein with an isoelectric point of 5.95. Phylogenetic analysis and amino acid alignments indicated that Cshsp19.0 is a member of the sHSP family. Cshsp19.0 was expressed at maximal levels in foreguts and showed the least amount of expression in fat bodies. Expression analysis in different developmental stages of C. suppressalis revealed that Cshsp19.0 was most highly expressed in 1st instar larvae. Furthermore, Cshsp19.0 was upregulated when insects were exposed to heat and cold stress for a 2-h period. There were significant differences in the male and female pupae in response to humidity; Cshsp19.0 expression increased in male pupae as RH increased, whereas the inverse pattern was observed in female pupae. Larvae exhibited a lower rate of survival when Cshsp19.0 was silenced by a nanomaterial-promoted RNAi method. The results confirm that Cshsp19.0 functions to increase environmental stress tolerance and regulates physiological activities in C. suppressalis.

Targeting Cancer Metabolism Breaks Radioresistance by Impairing the Stress Response

Simple Summary

Ionizing radiation is a major pillar in the therapy of solid tumors. However, normal tissue toxicities and radioresistance of tumor cells can limit the therapeutic success of radiotherapy. In this study, we investigated the coregulation of the cancer metabolism and the heat shock response with respect to radioresistance. Our results indicate that an inhibition of lactate dehydrogenase, either pharmacologically or by gene knockout of LDHA and LDHB, significantly increases the radiosensitivity in tumor cells by global impairing of the stress response. Therefore, inhibition of the lactate metabolism might provide a promising strategy in the future to improve the clinical outcome of patients with highly aggressive, therapy-resistant tumors.

Abstract

The heightened energetic demand increases lactate dehydrogenase (LDH) activity, the corresponding oncometabolite lactate, expression of heat shock proteins (HSPs) and thereby promotes therapy resistance in many malignant tumor cell types. Therefore, we assessed the coregulation of LDH and the heat shock response with respect to radiation resistance in different tumor cells (B16F10 murine melanoma and LS174T human colorectal adenocarcinoma). The inhibition of LDH activity by oxamate or GNE-140, glucose deprivation and LDHA/B double knockout (LDH^−/−) in B16F10 and LS174T cells significantly diminish tumor growth; ROS production and the cytosolic expression of different HSPs, including Hsp90, Hsp70 and Hsp27 concomitant with a reduction of heat shock factor 1 (HSF1)/pHSF1. An altered lipid metabolism mediated by a LDHA/B double knockout results in a decreased presence of the Hsp70-anchoring glycosphingolipid Gb3 on the cell surface of tumor cells, which, in turn, reduces the membrane Hsp70 density and increases the extracellular Hsp70 levels. Vice versa, elevated extracellular lactate/pyruvate concentrations increase the membrane Hsp70 expression in wildtype tumor cells. Functionally, an inhibition of LDH causes a generalized reduction of cytosolic and membrane-bound HSPs in tumor cells and significantly increases the radiosensitivity, which is associated with a G2/M arrest. We demonstrate that targeting of the lactate/pyruvate metabolism breaks the radioresistance by impairing the stress response.

The RNA-binding protein HuR is a novel target of Pirh2 E3 ubiquitin ligase

The RING-finger protein Pirh2 is a p53 family-specific E3 ubiquitin ligase. Pirh2 also ubiquitinates several other important cellular factors and is involved in carcinogenesis. However, its functional role in other cellular processes is poorly understood. To address this question, we performed a proteomic search for novel interacting partners of Pirh2. Using the GST-pulldown approach combined with LC-MS/MS, we revealed 225 proteins that interacted with Pirh2. We found that, according to the GO description, a large group of Pirh2-associated proteins belonged to the RNA metabolism group. Importantly, one of the identified proteins from that group was an RNA-binding protein ELAVL1 (HuR), which is involved in the regulation of splicing and protein stability of several oncogenic proteins. We demonstrated that Pirh2 ubiquitinated the HuR protein facilitating its proteasome-mediated degradation in cells. Importantly, the Pirh2-mediated degradation of HuR occurred in response to heat shock, thereby affecting the survival rate of HeLa cells under elevated temperature. Functionally, Pirh2-mediated degradation of HuR augmented the level of c-Myc expression, whose RNA level is otherwise attenuated by HuR. Taken together, our data indicate that HuR is a new target of Pirh2 and this functional interaction contributes to the heat-shock response of cancer cells affecting their survival.

Cr(VI)-induced DNA damage is lessened by the modulation of hsp70 via increased GSH de novo synthesis in Drosophila melanogaster

Hexavalent chromium [Cr(VI)] is a genotoxic chemical, and in the chemical-exposed organism, oxidative stress is one of the leading causative mechanisms of genotoxicity. Heat shock protein-70 (Hsp70) is reported to be modulated in environmental chemical exposed organisms. Inadequate information on the protective role of Hsp70 in chemical-induced DNA lesions prompted us to investigate this possibility in a well-studied genetically tractable in vivo model Drosophila melanogaster. In the midgut cells of Cr(VI)-exposed hsp70-knockout (KO), -knockdown (KD), and -overexpression Drosophila strains, no significant change in double-strand breaks generation was observed in comparison to similarly exposed w ¹¹¹⁸ and the respective genetic control strain after 48 h. Therefore, the role of hsp70 was investigated on oxidative DNA damage induction in the exposed organisms after 24 h. Oxidized DNA lesions (particularly oxidized purine-based lesions), 8-oxo-dG level, and oxidative stress endpoints were found to be significantly elevated in hsp70-KO and -KD strains in comparison to similarly exposed w ¹¹¹⁸ and respective genetic control strain. On the contrary, in ubiquitous hsp70-overexpression strain exposed to Cr(VI), these endpoints were significantly lowered concurrently with increased GSH level through elevated gclc, and gclm expression, Gclc level, and GCL activity. The study suggests that as a consequence of hsp70 overexpression, the augmented GSH level in cells vis-a-vis GSH de novo synthesis can counteract Cr(VI)-induced oxidized DNA lesions.

High-fat diet-induced obesity amplifies HSP70-2a and HSP90 expression in testicular tissue; correlation with proliferating cell nuclear antigen (PCNA)

AIMS

Current study was conducted to uncover the effect of high-fat diet (HFD)-induced obesity on heat shock proteins 70-2a and 90 expression levels and to investigate the network between these proteins with PCNA expression, endocrine status of testicular tissue and nucleotide backbone damages.

MAIN METHODS

For this purpose, 20 mature male Wistar rats were divided into two groups of control and HFD-received obese animals (n = 10/group). After 8 weeks from obesity approval, the animals were euthanized. The expression levels of Hsp70-2a, Hsp90 and PCNA were analyzed by qRT-PCR and immunohistochemical staining techniques. The Leydig cell distribution/mm² of interstitial tissue, serum level of testosterone, testicular total antioxidant capacity (TAC), and mRNA and DNA damage were investigated.

KEY FINDINGS

The obese (HFD-received) animals represented a remarkable (p < 0.05) increment in the mRNA levels of hsp70-2a and Hsp90, and the percentages of Hsp70-2a⁺ and Hsp90⁺ cells/seminiferous tubules with the same criteria. The PCNA mRNA level and the percentage of PCNA⁺ cells were decreased in the obese (HFD-received) group. The obesity, significantly decreased testicular TAC and with no effect on the Leydig cell distribution, but by reducing their steroidogenic activity resulted in a remarkable (p < 0.05) reduction in serum testosterone level. Finally, severe mRNA and DNA damage were revealed in the obese (HFD-received) group.

SIGNIFICANCE

Therefore, considering massive testicular DNA damage in the obese (HFD-received) animals, we can conclude that an increased expression of Hsp70-2a and Hsp90 with no harmony with PCNA could not properly maintain the cellular DNA integrity and/or appropriately finalize the DNA repair process.

Increased systemic HSP70B levels in spinal muscular atrophy infants

Despite newly available treatments for spinal muscular atrophy (SMA), novel circulating biomarkers are still critically necessary to track SMA progression and therapeutic response. To identify potential biomarkers, we performed whole‐blood RNA sequencing analysis in SMA type 1 subjects under 1 year old and age‐matched healthy controls. Our analysis revealed the Heat Shock Protein Family A Member 7 (HSPA7)/heat shock 70kDa protein 7 (HSP70B) as a novel candidate biomarker to track SMA progression early in life. Changes in circulating HSP70B protein levels were associated with changes in circulating neurofilament levels in SMA newborns and infants. Future studies will determine whether HSP70B levels respond to molecular therapies.

Evidence of bystander effect induced by radiofrequency radiation in a human neuroblastoma cell line

In previous studies we demonstrated that radiofrequency (RF) electromagnetic fields (EMF) is able to reduce DNA damage induced by a subsequent treatment with genotoxic agents, resembling the adaptive response, a phenomenon well known in radiobiology. In this study we report on the capability of the culture medium from SH-SY5Y neuroblastoma cells exposed to 1950 MHz to elicit, in recipient non-exposed cells, a reduction of menadione-induced DNA damage (P < 0.05; comet assay), indicating the capability of non-ionizing radiation to elicit a bystander effect. A comparable reduction was also detected in cultures directly exposed to the same EMF conditions (P < 0.05), confirming the adaptive response. In the same exposure conditions, we also evidenced an increase of heat shock protein 70 (hsp70) in culture medium of cells exposed to RF with respect to sham exposed ones (P < 0.05; western blot analysis), while no differences were detected in the intracellular content of hsp70. On the whole, our results evidence a protective effect of RF against menadione-induced DNA damage in directly and non-directly exposed cells, and suggest hsp70 pathway to be investigated as one of the potential candidate underpinning the interaction between RF exposure and biological systems.

Comparison of morphology, development and expression patterns of hsf and hsp11.0 of Cotesia chilonis under normal and high temperature

Cotesia chilonis (Munakata) is the dominant parasitic wasp of the rice pest, Chilo suppressalis (Walker), and is a valuable parasitic wasp for the prevention and control of C. suppressalis. In this study, developmental indicators and expression of Cchsp11.0 (heat shock protein 11.0) and Cchsf (heat shock factor) were compared for C. chilonis at 27 °C and 36 °C. Developmental duration, morphology, emergence rate, and number of C. chilonis offspring were shortened at 36 °C while the ratio of females to males increased. Cchsp11.0 and Cchsf were highly expressed in the 1^st instar stage at 36 °C, and Cchsp11.0 expression gradually decreased as C. chilonis matured; Cchsf expression was not correlated with Cchsp11.0 expression. Compared with 27 °C, the expression pattern of Cchsp11.0 and Cchsf was also not consistent, and Cchsp11.0 expression increased significantly at the adult stage. In conclusion, mildly high temperatures impact growth, development and reproduction of C. chilonis and stimulate the expression of Cchsp11.0 and Cchsf, and Cchsp11.0 and Cchsf play different roles in different developmental stages of C. chilonis at normal and high temperature.

Evaluation of the geroprotective effects of withaferin A in Drosophila melanogaster

Withanolides are a class of compounds usually found in plant extracts which are an attractive geroprotective drug design starting point. We evaluated the geroprotective properties of Withaferin A (WA) in vivo using the Drosophila model. Flies were supplemented by nutrient medium with WA (at a concentration of 1, 10, or 100 μM dissolved in ethanol) for the experiment group and 30 μM of ethanol for the control group. WA treatment at 10 and 100 μM concentrations prolong the median life span of D. melanogaster's male by 7.7, 9.6% (respectively) and the maximum life span (the age of death 90% of individuals) by 11.1% both. Also WA treatment at 1, 10 and 100 μM improved the intestinal barrier permeability in older flies and affected an expression of genes involved in antioxidant defense (PrxV), recognition of DNA damage (Gadd45), heat shock proteins (Hsp68, Hsp83), and repair of double-strand breaks (Ku80). WA was also shown to have a multidirectional effect on the resistance of flies to the prooxidant paraquat (oxidative stress) and 33° C hyperthermia (heat shock). WA treatment increased the resistance to oxidative stress in males at 4 and 7 week old and decreased it at 6 weeks old. It increased the male's resistance to hyperthermia at 2, 4 and 7 weeks old and decreased it at 3, 5 and 8 weeks old. WA treatment decreased the resistance to hyperthermia in females at 1, 2 and 3 weeks old and not affected on their resistance to oxidative stress.

Plasma Heat Shock Protein 90 Alpha: A Valuable Predictor of Early Chemotherapy Effectiveness in Advanced Non-Small-Cell Lung Cancer

Background

Heat shock protein-90 alpha (HSP90α) is more abundant in non-small-cell lung cancer (NSCLC) patients than in control individuals. However, whether it can reflect chemotherapy efficacy remains unknown. This study aimed to investigate the association of HSP90α with chemotherapy in advanced NSCLC.

Material/Methods

We retrospectively evaluated data from patients admitted to the Department of Respiratory Medicine, Shaoxing People’s Hospital, from September 2016 to September 2018 with stage IIIB or IV NSCLC and administered 4 cycles of third-generation platinum-based combination chemotherapy (2 drugs simultaneously). Based on the RECIST1.1 criteria, complete remission (CR), partial response (PR), and stable disease (SD) in 60 cases were determined before and after chemotherapy. Before chemotherapy and after 1, 2, and 4 cycles of chemotherapy, plasma HSP90α levels were quantitated by ELISA. Chest CT was performed before and after 2 and 4 cycles of chemotherapy.

Results

After 1–4 cycles of chemotherapy, plasma HSP90α levels were significantly lower than pre-chemotherapy levels (P<0.05). The sums of the longest tumor diameters after 2 and 4 cycles of chemotherapy were decreased compared with pre-chemotherapy values (P<0.05). Plasma HSP90α levels and tumor size showed no significant correlation before and after chemotherapy (r=0.244, P=0.06).

Conclusions

Plasma HSP90α can be considered a valuable predictor of early chemotherapy effectiveness in advanced NSCLC, and is positively correlated with tumor remission after chemotherapy. However, plasma HSP90α level is not correlated with tumor diameter and pathological type.

Deregulation of whole-transcriptome gene expression in zebrafish (Danio rerio) after chronic exposure to low doses of imatinib mesylate in a complete life cycle study

Imatinib mesylate (IM) is an anticancer drug that belongs to tyrosine kinase inhibitors. We report the results of the first investigation of the chronic exposure of zebrafish (Danio rerio) to IM. The exposure to IM (0.01, 1 and 100 μg/L) was initiated in adult fish and continued through hatching and the offspring generation for seven months. In addition to standard toxicological endpoints, induction of genotoxic effects and whole-genome transcriptome of liver samples of offspring generation of zebrafish were analysed. Exposure to IM did not affect the survival and growth of zebrafish, did not cause any histopathological changes, but it induced a marginal increase in the chromosomal damage in blood cells. The whole-genome transcriptome analyses demonstrated dose-dependent increase in the number of differentially expressed genes with a significantly higher number of deregulated genes in female fish compared to male. Differentially expressed genes included genes involved in response to DNA damage, cell cycle control and regulation of circadian rhythm. Based on the low genotoxic activity and the pattern of the changes in DNA damage responsive genes we consider that at current environmental exposure levels, IM represents low risk for genotoxic effects in aquatic organisms. Exposure to IM also induced deregulation of the expression of genes associated with steroidogenesis and hormone metabolism and function, which indicates hormone-disrupting activity of IM that has not been studied so far. The study provide new information on the potential consequences of chronic exposure to the residues of tyrosine kinase inhibitors, which remain to be further explored.

Effect of incubation temperature on lactogenic function of goat milk-derived mammary epithelial cells

In general, goat mammary epithelial cells (MECs) are cultured in vitro under 37 °C. We demonstrated previously that goat MECs differentiate under 37 °C although their body temperature is approximately 39 °C. This study aimed to investigate the influence of 39 °C on lactogenic differentiation of goat milk-derived MECs. The results revealed that HSP70 gene was significantly elevated at 1 h after an exposure to 39 °C but declined at 48 h thereafter. Oxidative stress status was not significantly affected by 39 °C. Expressions of CSN2, β-GALT1, α-LA, and Akt genes tended to increase after the differentiation under 39 °C. Secretion of lactose under 39 °C was not significantly lower than 37 °C. In conclusion, incubation temperature at 39 °C does not dramatically affect lactogenic function of goat milk-derived MECs.

Short-term cold stress and heat shock proteins in the crustacean Artemia franciscana

In their role as molecular chaperones, heat shock proteins (Hsps) mediate protein folding thereby mitigating cellular damage caused by physiological and environmental stress. Nauplii of the crustacean Artemia franciscana respond to heat shock by producing Hsps; however, the effects of cold shock on Hsp levels in A. franciscana have not been investigated previously. The effect of cold shock at 1 °C followed by recovery at 27 °C on the amounts of ArHsp90, Hsp70, ArHsp40, and ArHsp40-2 mRNA and their respective proteins in A. franciscana nauplii was examined by quantitative PCR (qPCR) and immunoprobing of western blots. The same Hsp mRNAs and proteins were also quantified during incubation of nauplii at their optimal growth temperature of 27 °C. qPCR analyses indicated that the abundance of ArHsp90, Hsp70, and ArHsp40 mRNA remained relatively constant during both cold shock and recovery and was not significantly different compared with levels at optimal temperature. Western blotting revealed that ArHsp90, ArHsp40, and ArHsp40-2 were generally below baseline, but at detectable levels during the 6 h of cold shock, and persisted in early recovery stages before declining. Hsp70 was the only protein that remained constant in quantity throughout cold shock and recovery. By contrast, all Hsps declined rapidly during 6 h when nauplii were incubated continuously at 27 °C optimal temperature. Generally, the amounts of ArHsp90, ArHsp40, and ArHsp40-2 were higher during cold shock/recovery than those during continuous incubation at 27 °C. Our data support the conclusion that low temperature preserves Hsp levels, making them available to assist in protein repair and recovery after cold shock.

Long-term Preservation of Testicular Tissue Integrity and Viability Using Vitrification in the Endangered Black-Footed Ferret (Mustela Nigripes)

Simple Summary

In addition to semen preservation, systematic cryo-banking of testicular tissues is critical to preserve the genetic value of recently deceased or neutered black-footed ferrets. Mature sperm cells produced from vitrified-warmed tissues could be used for in vitro fertilization over multiple generations, which would enhance the genetic management of this rare and endangered species. The objective of the study was to evaluate structural and functional properties of vitrified testicular tissues directly after warming or after warming plus a short period of in vitro culture. Fresh, vitrified/warmed, and warmed/cultured tissues from five adults were analyzed through histology, DNA fragmentation, cell survival, and germ cell composition. Percentages of intact seminiferous tubules decreased right after vitrification/warming and improved after culture (reaching same percentages as the fresh controls). While proportions of cells with intact DNA and viable cells were affected by vitrification/warming, they were then similar or better after additional culture than in the fresh tissue. Proportions of cells labeled with differentiation markers also increased during in vitro culture. We demonstrated for the first time that black-footed ferret testicular tissues can be vitrified and revived, which will potentially contribute to new strategies to enhance assisted reproduction as well as conservation efforts in that rare and endangered species.

Abstract

Systematic cryo-banking of semen and testicular tissues is critical to preserve the genetic value of recently deceased or neutered black-footed ferrets (BFFs). Specifically, recovering or producing mature sperm cells from vitrified-warmed issues offers additional options in assisted reproduction. This could, in turn, enhance the genetic management of this rare and endangered species over multiple generations. The objective of the study was to evaluate structural properties, DNA fragmentation, cell viability, and germ cell composition in vitrified testicular tissues from BFFs directly after warming or after warming plus a short in vitro culture period. Tissue biopsies from five adult BFFs were either kept fresh or vitrified with a standard protocol (using dimethylsulphoxide (DMSO) and glycerol) and warmed at 50 °C for 5 s. Some of the warmed samples were then cultured in vitro for 24 h. Fresh, warmed, and warmed/cultured tissues were analyzed using different indicators: histology of seminiferous tubules, intact Sertoli cells (vimentin labeling), DNA integrity, cell viability, germ cell composition (Oct4 and Boule labeling). Percentages of intact seminiferous tubules decreased after vitrification/warming and returned to the level of fresh samples after culture. While percentages of cells labeled with vimentin, with intact DNA integrity, or proportions of viable cells were affected by vitrification/warming, they all reached similar or better levels than the fresh tissue after culture. Proportions of cells labeled with Boule antibodies also improved during in vitro culture post-warming. We demonstrated for the first time that BFF testes subjected to vitrification, rapid warming, and short in vitro culture were viable and maintained the ability to resume germ cell progression. Cryopreserved testicular tissues could potentially contribute to new strategies to enhance BFF assisted reproduction as well as conservation efforts.

Low-Dose Hsp90 Inhibitor Selectively Radiosensitizes HNSCC and Pancreatic Xenografts

PURPOSE

Treatment approaches using Hsp90 inhibitors at their maximum tolerated doses (MTDs) have not produced selective tumor toxicity. Inhibition of Hsp90 activity causes degradation of client proteins including those involved in recognizing and repairing DNA lesions. We hypothesized that if DNA repair proteins were degraded by concentrations of an Hsp90 inhibitor below those required to cause nonspecific cytotoxicity, significant tumor-selective radiosensitization might be achieved.

EXPERIMENTAL DESIGN

Tandem mass tagged-mass spectrometry was performed to determine the effect of a subcytotoxic concentration of the Hsp90 inhibitor, AT13387 (onalespib), on global protein abundance. The effect of AT13387 on in vitro radiosensitization was assessed using a clonogenic assay. Pharmacokinetics profiling was performed in mice bearing xenografts. Finally, the effect of low-dose AT13387 on the radiosensitization of three tumor models was assessed.

RESULTS

A subcytotoxic concentration of AT13387 reduced levels of DNA repair proteins, without affecting the majority of Hsp90 clients. The pharmacokinetics study using one-third of the MTD showed 40-fold higher levels of AT13387 in tumors compared with plasma. This low dose enhanced Hsp70 expression in peripheral blood mononuclear cells (PBMCs), which is a biomarker of Hsp90 inhibition. Low dose monotherapy was ineffective, but when combined with radiotherapy, produced significant tumor growth inhibition.

CONCLUSIONS

This study shows that a significant therapeutic ratio can be achieved by a low dose of Hsp90 inhibitor in combination with radiotherapy. Hsp90 inhibition, even at a low dose, can be monitored by measuring Hsp70 expression in PBMCs in human studies.

Melatonin regulates oxidative stress and apoptosis in fetal hearts of pinealectomised RUPP rats

OBJECTIVE

This study aimed to investigate the effects of melatonin on cardiac oxidative stress and apoptosis in the fetal heart in RUPP rats.

METHODS

The fetal heart samples were obtained from melatonin administrated RUPP rats.

RESULTS

Our results indicate that preeclampsia exacerbated by melatonin deficiency triggers hypoxic conditions, both mis/un-folded protein response, oxidative stress-induced DNA damage and apoptosis. Melatonin treatment provided significant therapeutic effects on fetal hearts via regulating all these stress response at cellular and molecular levels.

CONCLUSION

Melatonin may be considered as a potential molecule for development of preventive strategies to reduce the PE induced risk of cardiovascular diseases in offspring.

The cellular heat shock response monitored by chemical exchange saturation transfer MRI

CEST-MRI of the rNOE signal has been demonstrated in vitro to be closely linked to the protein conformational state. As the detectability of denaturation and aggregation processes on a physiologically relevant scale in living organisms has yet to be verified, the aim of this study was to perform heat-shock experiments with living cells to monitor the cellular heat-shock response of the rNOE CEST signal. Cancer cells (HepG2) were dynamically investigated after a mild, non-lethal heat-shock of 42 °C for 20 min using an MR-compatible bioreactor system at 9.4 T. Reliable and fast high-resolution CEST imaging was realized by a relaxation-compensated 2-point contrast metric. After the heat-shock, a substantial decrease of the rNOE CEST signal by 8.0 ± 0.4% followed by a steady signal recovery within a time of 99.1 ± 1.3 min was observed in two independent trials. This continuous signal recovery is in coherence with chaperone-induced refolding of heat-shock induced protein aggregates. We demonstrated that protein denaturation processes influence the CEST-MRI signal on a physiologically relevant scale. Thus, the protein folding state is, along with concentration changes, a relevant physiological parameter for the interpretation of CEST signal changes in diseases that are associated with pathological changes in protein expression, like cancer and neurodegenerative diseases.

Short term temperature elevation during IVM affects embryo yield and alters gene expression pattern in oocytes, cumulus cells and blastocysts in cattle

Heat stress causes subfertility in cattle by inducing alterations in steroidogenic capacity, follicular function and ovulation defects, which eventually negatively affect oocyte quality and embryo survival. Here, the effects of short, moderate temperature elevation during IVM, on embryo yield, and on the expression of various genes was evaluated. In 8 replicates, cumulus oocyte complexes (COCs) were matured for 24 h at 39 °C (controls n = 605) or at 41 °C from hour 2 to hour 8 of IVM (treated, n = 912), fertilized, and presumptive zygotes were cultured for 9 days at 39 °C. Cleavage and embryo formation rates were evaluated 48 h post insemination and on days 7, 8, 9 respectively. Cumulus cells, oocytes and blastocysts from 5 replicates were snap frozen for the relative expression analysis of genes related to metabolism, thermal and oxidative stress response, apoptosis, and placentation. In treated group, cleavage and embryo formation rates were statistically significantly lower compared with the control (cleavage 86.7% vs 74.2%; blastocysts: day 7, 29.9% vs 19.7%, day 8, 34.2% vs 22.9% and day 9 35.9% vs 24.5%). Relative mRNA abundance of three genes in cumulus cells (HSP90AA1, CPT1B, G6PD) and three genes in blastocysts (DNMT3A, PLAC8, GPX1) indicated significantly different expression between groups (p < 0.05)., The expression of G6PD, SOD2, GXP1 in oocytes and PTGS2 in blastocysts tended to differ among groups (0.05<p < 0.08). Heat stress altered (p < 0.05) the correlation of expression between HSPs and other genes in oocytes (G6PD, GPX1, CCNB1), cumulus cells (LDH, CCNB1) and blastocysts (AKR1B1, PLAC8). These results imply that exposure of oocytes to elevated temperature, even for only 6 h, disrupts the developmental competence of the oocytes, suppresses blastocyst yield and significantly alters the coordinated pattern of gene expressions.

Advances in DNA Repair-Emerging Players in the Arena of Eukaryotic DNA Repair

Genomic DNA is constantly damaged by factors produced during natural metabolic processes as well as agents coming from the external environment. Considering such a wide array of damaging agents, eukaryotic cells have evolved a DNA damage response (DRR) that opposes the influence of deleterious factors. Despite the broad knowledge regarding DNA damage and repair, new areas of research are emerging. New players in the field of DDR are constantly being discovered. The aim of this study is to review current knowledge regarding the roles of sirtuins, heat shock proteins, long-noncoding RNAs and the circadian clock in DDR and distinguish new agents that may have a prominent role in DNA damage response and repair.

Long noncoding RNA and mRNA profiling of hypothalamic-pituitary-mammary gland axis in lactating sows under heat stress

Heat stress (HS) seriously affects sow lactation performance and Long non-coding RNAs (lncRNAs) play vital roles in the regulation of transcription and post transcription. However, the mechanism of lncRNAs expression affecting lactation performance on the hypothalamus-pituitary-mammary axis of sows is still unclear. In this study, we performed RNA sequencing and bioinformatics analysis of the hypothalamus, pituitary, and mammary gland tissues of lactating sows under HS and thermal comfort. In total, the analysis identified 658, 6021, and 6745 differently expressed (DE) mRNAs, 26, 126, and 169 DE lncRNAs between comparison groups in the hypothalamus, pituitary, and mammary glands, respectively. The hormone genes and most DE mRNAs encoding heat shock protein were differently expressed in the HS group. In addition, 2, 60, and 86 pairs of DE lncRNAs and mRNAs correlation were observed in those tissues, respectively. Some lncRNAs may be involved in the regulation of lactation performance in the HS sows.

Balance between Health Risks and Benefits for Outdoor Workers Exposed to Solar Radiation: An Overview on the Role of Near Infrared Radiation Alone and in Combination with Other Solar Spectral Bands

Near infrared or infrared A (IRA) accounts for over 40% of the solar spectrum (SS) and is able to reach subcutaneous tissue as well as the retina. Outdoor workers are occupationally exposed to solar radiation (SR), but the level of exposure may differ widely depending on the job performed, time spent outdoors, latitude, altitude, season, personal protection, etc. Until now, risk assessment and management for outdoor workers has focused on the prevention of both acute and long-term effects on the eye and the skin due to solar ultraviolet radiation (UVR) with little consideration of the other components of the SS (a possible exception is represented by visible radiation with reference to the eye). A growing body of evidence coming from in vitro studies indicates that IRA is involved in cellular reactive oxygen species (ROS) production and may interfere with the respiratory chain in the mitochondria. Moreover, it can modulate gene expression and some metabolic pathways. The biological action of IRA is only partly attributable to a thermal mechanism, should it be also involved in photochemical ones. The cellular and molecular pathways affected by IRA are partly similar and partly different with respect to those involved in the case of visible ultraviolet A (UVA) and ultraviolet B (UVB) radiation. Consequently, the net effect of the SS is very difficult to predict at different levels of the biological organization, making more difficult the final balance of health risk and benefits (for the skin, eye, immune system, blood pressure, etc.) in a given exposure situation. Moreover, few in vivo studies and no epidemiological data are presently available in this regard. Investigating this topic may contribute to better defining the individual exposome. More practically, it is expected to bring benefits to the risk assessment and management for outdoor workers exposed to SS, contributing to: (1) better definition of the individual profiles of susceptibility, (2) more focused preventive and protective measures, (3) better implementation of the health surveillance and (4) a more effective information and training.

Aspirin Enhances the Protection of Hsp90 from Heat-Stressed Injury in Cardiac Microvascular Endothelial Cells Through PI3K-Akt and PKM2 Pathways

Heat stress (HS) often causes sudden death of humans and animals due to heart failure, mainly resulting from the contraction of cardiac microvasculature followed by myocardial ischemia. Cardiac microvascular endothelial cells (CMVECs) play an important role in maintaining vasodilatation. Aspirin (ASA) is well known for its protective abilities of febrile animals. However, there is little knowledge about molecular resistance mechanisms of CMVECs and which role ASA may play in this context. Therefore, we used a heat stress model of rat cardiac microvascular endothelial cell cultures in vitro and investigated the cell injuries and molecular resistance mechanism of CMVECs caused by heat stress, and the effect of aspirin (ASA) on it. HS induced severe pathological damage of CMVECs and cellular oxidative stress and dysfunction of NO release. Hsp90 was proven to be indispensable for resisting HS-injury of CMVECs through PI3K-Akt and PKM2 signaling pathways. Meanwhile, PKM2 functioned in reducing Akt phosphorylation. ASA treatment of CMVECs induced a significant expression of Hsp90, which promoted both Akt and PKM2 signals, which are beneficial for relieving HS damage and maintaining the function of CMVECs. Akt activation also promoted HSF-1 that regulates the expression of Hsp70, which is known to assist Hsp90′s molecular chaperone function and when released to the extracellular liquid to protect myocardial cells from HS damage. To the best of our knowledge, this is the first study to show that HS damages CMVECs and the protection mechanism of Hsp90 on it, and that ASA provides a new potential strategy for regulating cardiac microcirculation preventing HS-induced heart failure.

Heat stress modulates nucleotide excision repair capacity in zebrafish (Danio rerio) early and mid-early embryos via distinct mechanisms

Discharge of heated effluent at 8-12 °C above ambient into water areas is known to retard the growth of aquatic organisms due to heat stress. Nucleotide excision repair (NER) maintains genome integrity by removing helix-distorting adducts such as UV-induced DNA lesions. This study explored how NER in zebrafish (Danio rerio) embryos at different hours post fertilization (hpf) responded to + 8.5 °C heat shock for 30 min. Our transcription-based repair assay monitoring the ability of zebrafish extracts to upregulate a UV-suppressed gene expression detected a 2-fold increase of NER capacity in 10 hpf early embryos after heat stress. In contrast, heat stress caused a mild inhibition of NER capacity in 24 hpf mid-early embryos. Heat-treated and untreated 10 hpf zebrafish extracts displayed similar levels of UV-damaged-DNA binding activities, while an apparently weaker (6-4) photoproduct (6-4 PP) binding activity was present in heat-stressed 24 hpf zebrafish extracts. Heat stress enhanced UV-induced NER in 10 hpf embryos by increasing the efficiency of damage incision/excision based on both genomic DNA electrophoresis and terminal deoxytransferase (TdT)-mediated end labeling assay. UV-irradiated embryos preexposed to heat stress produced a significantly larger amount of NER-associated DNA fragments about 20-30 nucleotides in length than embryos only heat-treated or irradiated. Correlated with its inhibitory effect on 6-4 PP damage recognition, heat stress downregulated damage incision/excision activities in 24 hpf embryos. Hence, thermal stress may positively or negatively modulate NER capacity in zebrafish embryos at different stages by targeting at the step of DNA incision/excision or damage recognition.

Genomic regions and pathways associated with thermotolerance in layer-type strain Taiwan indigenous chickens

This study aimed to investigate genetic markers and candidate genes associated with thermotolerance in a layer-type strain Taiwan indigenous chickens exposed to acute heat stress. One hundred and ninety-two 30-week-old roosters were subjected to acute heat stress. Changes in body temperature (BT, ΔT) were calculated by measuring the difference between the initial BT and the highest BT during heat stress and the results were categorized into dead, susceptible, tolerant, and intermediate groups depending on their survival and ΔT values at the end of the experiment. A genome-wide association study on survival and ΔT values was conducted using the Cochran-Armitage trend test and Fisher's exact test. Association analyses identified 80 significant SNPs being annotated to 23 candidate genes, 440 SNPs to 71 candidate genes, 64 SNPs to 25 candidate genes, and 378 SNPs to 78 candidate genes in the dead versus survivor, tolerant versus susceptible, intermediate versus tolerant, and intermediate versus susceptible groups, respectively. The annotated genes were associated with apoptosis, cellular stress responses, DNA repair, and metabolic oxidative stress. In conclusion, the identified SNPs of candidate genes provide insights into the potential mechanisms underlying physiological responses to acute heat stress in chickens.

Effect of boar semen supplementation with recombinant heat shock proteins during summer

Artificial insemination (AI) in pigs is mainly performed with refrigerated boar semen. There is a marked negative seasonal effect on the quality of boar sperm, mainly due to relatively greater ambient temperatures; to counteract this thermal stress, sperm cells possess natural defensive mechanisms such as Heat Shock Proteins (HSPs) that prevent protein denaturation. Thus, the objective of this research was to improve the quality of commercial boar semen collected during the summer when ambient temperatures are greater using recombinant HSPs. For this purpose, different concentrations (0.1, 0.5 and 1 μg/ml) of recombinant heat shock proteins (HSPD1, HSPA8 or HSP86) were added to commercial boar semen and there was cooling for 48 h at 17 °C. After this storage period, sperm quality was assessed by analyzing sperm viability, mitochondrial membrane potential and plasma membrane lipid organization using flow cytometry; additionally, sperm motility was examined using a CASA system. Also, in vitro fertilization (IVF) using HSP-supplemented boar semen was performed and the quality of the embryos produced was evaluated using quantitative real-time polymerase chain reaction (qPCR) analyzing the relative abundance of mRNA transcripts for genes encoding for embryo quality-related proteins (BAX, TFAM, POLG and POG2). Sperm quality variables, blastocyst rates and the abundance of mRNA transcripts for the selected genes were not affected by the presence of recombinant HSPs at any concentration. These results indicate that the supplementation of commercial seminal doses with recombinant HSPs does not improve boar sperm quality or fertility during the summer months when ambient temperatures are greater.

Melatonin, protocatechuic acid and hydroxytyrosol effects on vitagenes system against alpha-synuclein toxicity

Preventing the abnormal assembly of α-synuclein (α-Syn) and the correct modulation of vitagenes system exercise strong neuroprotective effects. It has been reported that melatonin (MEL), protocatechuic acid (PCA) and hydroxytyrosol (HT) reduce α-Syn toxicity. Their effect on the vitagenes system of PC12 cells have not been explored yet. These bioactive can cross the blood brain barrier (BBB). Therefore, this work aims to evaluate the inhibitory and destabilising capacities of MEL, PCA, HT, and their combinations on α-Syn kinetics and effects on vitagenes system (sirtuin-1 (SIRT-1), sirtuin-2 (SIRT-2), heme oxygenase (HO-1) and heat shock protein 70 (Hsp-70)). In vitro techniques (Thioflavin T (ThT), Transmission Electronic Microscopy (TEM), electrophoresis, MTT assay and qPCR) were used. Compounds, both individually and simultaneously were able to decrease the toxicity induced by α-Syn. Concurrently, occurrence of PCA (100 μM) +HT (100 μM) showed the highest inhibitory effect against α-Syn fibril formation and destabilisation of α-Syn fibrils (88 and 62%, respectively). Moreover, these compounds increased the expression of SIRT-2, HO-1 and Hsp70, contributing to a neuroprotective effect. In addition, the most important result is the increase on the expression of SIRT-2 caused by the combination of MEL + HT + PCA in the absence of α-Syn fibrils.

Identification and validation of a prognostic proteomic signature for cervical cancer

OBJECTIVE

To date, The Cancer Genome Atlas (TCGA) has provided the most extensive molecular characterization of invasive cervical cancer (ICC). Analysis of reverse phase protein array (RPPA) data from TCGA samples showed that cervical cancers could be stratified into 3 clusters exhibiting significant differences in survival outcome: hormone, EMT, and PI3K/AKT. The goals of the current study were to: 1) validate the TCGA RPPA results in an independent cohort of ICC patients and 2) to develop and validate an algorithm encompassing a small antibody set for clinical utility.

METHODS

Subjects consisted of 2 ICC patient cohorts with accompanying RPPA and clinical-pathologic data: 155 samples from TCGA (TCGA-155) and 61 additional, unique samples (MCW-61). Using data from 173 common RPPA antibodies, we replicated Silhouette clustering analysis in both ICC cohorts. Further, an index score for each patient was calculated from the survival-associated antibodies (SAAs) identified using Random survival forests (RSF) and the Cox proportional hazard regression model. Kaplan-Meier survival analysis and the log-rank test were performed to assess and compare cluster or risk group survival outcome.

RESULTS

In addition to validating the prognostic ability of the proteomic clusters reported by TCGA, we developed an algorithm based on 22 unique antibodies (SAAs) that stratified women with ICC into low-, medium-, or high-risk survival groups.

CONCLUSIONS

We provide a signature of 22 antibodies which accurately predicted survival outcome in 2 separate groups of ICC patients. Future studies examining these candidate biomarkers in additional ICC cohorts is warranted to fully determine their clinical potential.

Heat stress-induced alterations in the expression of genes associated with gonadal integrity of the teleost Puntius sophore

Temperature plays an important role on reproductive physiology of vertebrates including mammals, fish, and birds. It has varying effects on fish reproduction depending on the species; higher temperatures favor the spring-spawning species, while lower temperatures stimulate reproduction in autumn spawners. To evaluate the impact of high temperature on the reproductive physiology of minnow Puntius sophore, we carried out expression analysis of selected genes associated with gamete quality (hsp60, hsp70, hsp90, hsf1, vtg), pleuripotency (sox2, oct4, nanog), and sex determination (dmrt1) in gonads (ovary and testis) of P. sophore, heat stressed for different time periods (36 °C/7 days or 60 days) using real-time quantitative polymerase chain reaction (RT-qPCR). Expression of most of the hsp, vtg, and pleuripotency marker genes sox-2, oct-4, and nanog genes was downregulated in both ovary and testis of heat-stressed fish. The expression of dmrt-1 was upregulated in testis but downregulated in ovary of the heat-stressed fish which could be a male favoring effect of high temperature in P. sophore. This study suggests that the reproductive physiology and health of the nutrient dense P. sophore would be negatively affected by high temperature stress.

Whole-body hyperthermia in combination with systemic therapy in advanced solid malignancies

Whole-body hyperthermia (WBH) might be beneficial for patients with metastasized solid malignancies when combined with systemic therapy. This review identified and summarized the phase I/II studies (n = 13/14) conducted using this combination of therapies. Most of the phase II studies used radiant heating methods in a thermal dose of 41.8 °C (1 h). All studies used classic chemotherapy. Great inter-study heterogeneity was observed regarding treatment regimes, included patients and reported response rates (12-89%). Ovarian cancer, colorectal adenocarcinoma, lung cancer and sarcoma have been studied most. Most reported toxicity (grade 3/4) was myelosuppression. Treatment related mortality was present (4 patients) in three out 14 phase II studies (350 evaluable patients, over 966 cycles of WBH with chemotherapy). Absence of phase III trials makes the additive value of WBH highly speculative. As modern oncology offers many less invasive treatments options, it is unlikely WBH will ever find its way in routine clinical care.

Epicatechin Reduces Spatial Memory Deficit Caused by Amyloid-β25⁻35 Toxicity Modifying the Heat Shock Proteins in the CA1 Region in the Hippocampus of Rats

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by dementia and the aggregation of the amyloid beta peptide (Aβ). Aβ_25-35 is the most neurotoxic sequence, whose mechanism is associated with the neuronal death in the Cornu Ammonis 1 (CA1) region of the hippocampus (Hp) and cognitive damage. Likewise, there are mechanisms of neuronal survival regulated by heat shock proteins (HSPs). Studies indicate that pharmacological treatment with flavonoids reduces the prevalence of AD, particularly epicatechin (EC), which shows better antioxidant activity. The aim of this work was to evaluate the effect of EC on neurotoxicity that causes Aβ_25-35 at the level of spatial memory as well as the relationship with immunoreactivity of HSPs in the CA1 region of the Hp of rats. Our results show that EC treatment reduces the deterioration of spatial memory induced by the Aβ_25-35, in addition to reducing oxidative stress and inflammation in the Hp of the animals treated with EC + Aβ_25-35. Likewise, the immunoreactivity to HSP-60, -70, and -90 is lower in the EC + Aβ_25-35 group compared to the Aβ_25-35 group, which coincides with a decrease of dead neurons in the CA1 region of the Hp. Our results suggest that EC reduces the neurotoxicity induced by Aβ_25-35, as well as the HSP-60, -70, and -90 immunoreactivity and neuronal death in the CA1 region of the Hp of rats injected with Aβ_25-35, which favors an improvement in the function of spatial memory.

The Molecular Chaperone Heat Shock Protein 70 Controls Liver Cancer Initiation and Progression by Regulating Adaptive DNA Damage and Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Signaling Pathways

Delineating the mechanisms that drive hepatic injury and hepatocellular carcinoma (HCC) progression is critical for development of novel treatments for recurrent and advanced HCC but also for the development of diagnostic and preventive strategies. Heat shock protein 70 (HSP70) acts in concert with several cochaperones and nucleotide exchange factors and plays an essential role in protein quality control that increases survival by protecting cells against environmental stressors. Specifically, the HSP70-mediated response has been implicated in the pathogenesis of cancer, but the specific mechanisms by which HSP70 may support malignant cell transformation remains to be fully elucidated. Here, we show that genetic ablation of HSP70 markedly impairs HCC initiation and progression by distinct but overlapping pathways. This includes the potentiation of the carcinogen-induced DNA damage response, at the tumor initiation stage, to increase the p53-dependent surveillance response leading to the cell cycle exit or death of genomically damaged differentiated pericentral hepatocytes, and this may also prevent their conversion into more proliferating HCC progenitor cells. Subsequently, activation of a mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) negative feedback pathway diminishes oncogenic signals, thereby attenuating premalignant cell transformation and tumor progression. Modulation of HSP70 function may be a strategy for interfering with oncogenic signals driving liver cell transformation and tumor progression, thus providing an opportunity for human cancer control.

A nuclear phosphoinositide kinase complex regulates p53

The tumour suppressor p53 (encoded by TP53) protects the genome against cellular stress and is frequently mutated in cancer. Mutant p53 acquires gain-of-function oncogenic activities that are dependent on its enhanced stability. However, the mechanisms by which nuclear p53 is stabilized are poorly understood. Here, we demonstrate that the stability of stress-induced wild-type and mutant p53 is regulated by the type I phosphatidylinositol phosphate kinase (PIPKI-α (also known as PIP5K1A)) and its product phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P₂). Nuclear PIPKI-α binds to p53 upon stress, resulting in the production and association of PtdIns(4,5)P₂ with p53. PtdIns(4,5)P₂ binding promotes the interaction between p53 and the small heat shock proteins HSP27 (also known as HSPB1) and αB-crystallin (also known as HSPB5), which stabilize nuclear p53. Moreover, inhibition of PIPKI-α or PtdIns(4,5)P₂ association results in p53 destabilization. Our results point to a previously unrecognized role of nuclear phosphoinositide signalling in regulating p53 stability and implicate this pathway as a promising therapeutic target in cancer.

Living in a multi-stressors environment: An integrated biomarker approach to assess the ecotoxicological response of meagre (Argyrosomus regius) to venlafaxine, warming and acidification

Pharmaceuticals, such as the antidepressant venlafaxine (VFX), have been frequently detected in coastal waters and marine biota, and there is a growing body of evidence that these pollutants can be toxic to non-target marine biota, even at low concentrations. Alongside, climate change effects (e.g. warming and acidification) can also affect marine species' physiological fitness and, consequently, compromising their ability to cope with the presence of pollutants. Yet, information regarding interactive effects between pollutants and climate change-related stressors is still scarce. Within this context, the present study aims to assess the differential ecotoxicological responses (antioxidant activity, heat shock response, protein degradation, endocrine disruption and neurotoxicity) of juvenile fish (Argyrosomus regius) tissues (muscle, gills, liver and brain) exposed to VFX (via water or feed), as well as to the interactive effects of warming (ΔT °C = +5 °C) and acidification (ΔpCO₂ ~ +1000 µatm, equivalent to ΔpH = -0.4 units), using an integrated multi-biomarker response (IBR) approach. Overall, results showed that VFX toxicity was strongly influenced by the uptake pathway, as well as by warming and acidification. More significant changes (e.g. increases surpassing 100% in lipid peroxidation, LPO, heat shock response protein content, HSP70/HSC70, and total ubiquitin content, Ub,) and higher IBR index values were observed when VFX exposure occurred via water (i.e. average IBR = 19, against 17 in VFX-feed treatment). The co-exposure to climate change-related stressors either enhanced (e.g. glutathione S-transferases activity (GST) in fish muscle was further increased by warming) or attenuated the changes elicited by VFX (e.g. vitellogenin, VTG, liver content increased with VFX feed exposure acting alone, but not when co-exposed with acidification). Yet, increased stress severity was observed when the three stressors acted simultaneously, particularly in fish exposed to VFX via water (i.e. average IBR = 21). Hence, the distinct fish tissues responses elicited by the different scenarios emphasized the relevance of performing multi-stressors ecotoxicological studies, as such approach enables a better estimation of the environmental hazards posed by pollutants in a changing ocean and, consequently, the development of strategies to mitigate them.

Interplay between heat shock proteins, inflammation and cancer: a potential cancer therapeutic target

The historical relationship between cancer and inflammation has long been evaluated, and dates back to the early work of Virchow (1863), where he hypothesised that chronic inflammation as a direct cause of tissue injury and infection, could actually promote tissue proliferation. At that period in time however, the exact mechanisms that mediated this relationship were little understood. Subsequent studies have since then demonstrated that chronic inflammation plays significant roles in microenvironments, mostly in the progression of tumours, probably, through over-secretion of proinflammatory cytokines and other immune-killing apparatus such as reactive oxygen species (ROS) which cause damage to normal cells leading to DNA damage and increased cellular mutation rates. Recently, the identification of DNA lesion 5-chlorocytosine (5-CIC) created by hypochlorous acid (HOCl) secreted to nullify or kill infectious agents and toll-like receptor 4 (TLR4)-mediated chronic inflammation in the human gut, has become the latest evidence linking inflammation directly to cancer. The key to cellular survival and adaptation under unfavourable or pathological conditions is the expression of heat shock proteins (HSPs) also called molecular chaperones. These proteins play essential roles in DNA repair processes by maintaining membrane integrity, orderliness and stability of client proteins that play prominent roles in DNA repair mechanisms. More so, HSPs have also been shown to modulate the effects of pro-inflammatory/apoptotic cytokines through the inhibition of cascades leading to the generation of ROS-mediated DNA damage, while promoting the DNA repair mechanism, thus playing prominent roles in various stages of DNA repair and cancer progression. Hence, studies targeting HSPs and their inhibitors in inflammation, DNA damage, and repair, could improve current cancer therapeutic efficiency. Here the focus will be on the relationship between HSPs, inflammation and cancer, as well as roles of HSPs in DNA damage response (DDR).

CRYAB protects cardiomyocytes against heat stress by preventing caspase-mediated apoptosis and reducing F-actin aggregation

CRYAB is a small heat shock protein (sHSP) that has previously been shown to protect the heart against various cellular stresses; however, its precise function in myocardial cell injury caused by heat stress remains unclear. This study aimed to investigate the molecular mechanism by which CRYAB protects cardiomyocytes against heat stress. We constructed two H9C2 cell lines that stably express CRYAB protein to differing degrees: CRYAB-5 and CRYAB-7. Both CRYAB-5 and CRYAB-7 showed significantly reduced granular degeneration and vacuolar degeneration following heat stress compared to control cells. In addition, CRYAB overexpression in H9C2 cells relieved cell cycle proportion at the G0/G1 phase following heat stress compared to control cells. These protective effects were associated with the level of CRYAB protein expression. Our immunofluorescence analysis showed CRYAB could translocate from the cytoplasm to the nucleus under heat stress conditions, but that CRYAB co-localized with F-actin (which accumulates under stress conditions). Indeed, overexpression of CRYAB significantly reduced the aggregation of F-actin in H9C2 cells caused by heat stress. Furthermore, overexpressing CRYAB protein significantly reduced the apoptosis of cardiomyocytes induced by heat stress, likely by reducing the expression of cleaved-caspase 3. Collectively, our results show overexpression of CRYAB significantly increases the heat resistance of H9C2 cardiomyocytes, likely by reducing F-actin aggregation (thus stabilizing the cytoskeleton), regulating the cell cycle, and preventing caspase-mediated apoptosis.

Mutations, protein homeostasis, and epigenetic control of genome integrity

From bacteria to humans, ancient stress responses enable organisms to contend with damage to both the genome and the proteome. These pathways have long been viewed as fundamentally separate responses. Yet recent discoveries from multiple fields have revealed surprising links between the two. Many DNA-damaging agents also target proteins, and mutagenesis induced by DNA damage produces variant proteins that are prone to misfolding, degradation, and aggregation. Likewise, recent studies have observed pervasive engagement of a p53-mediated response, and other factors linked to maintenance of genomic integrity, in response to misfolded protein stress. Perhaps most remarkably, protein aggregation and self-assembly has now been observed in multiple proteins that regulate the DNA damage response. The importance of these connections is highlighted by disease models of both cancer and neurodegeneration, in which compromised DNA repair machinery leads to profound defects in protein quality control, and vice versa.

Vitamin C and sodium bicarbonate enhance the antioxidant ability of H9C2 cells and induce HSPs to relieve heat stress

Heat stress is exacerbated by global warming and affects human and animal health, leading to heart damage caused by imbalances in reactive oxygen species (ROS) and the antioxidant system, acid-base chemistry, electrolytes and respiratory alkalosis. Vitamin C scavenges excess ROS, and sodium bicarbonate maintains acid-base and electrolyte balance, and alleviates respiratory alkalosis. Herein, we explored the ability of vitamin C alone and in combination with equimolar sodium bicarbonate (Vitamin C-Na) to stimulate endogenous antioxidants and heat shock proteins (HSPs) to relieve heat stress in H9C2 cells. Control, vitamin C (20 μg/ml vitamin C for 16 h) and vitamin C-Na (20 μg/ml vitamin C-Na for 16 h) groups were heat-stressed for 1, 3 or 5 h. Granular and vacuolar degeneration, karyopyknosis and damage to nuclei and mitochondria were clearly reduced in treatment groups, as were apoptosis, lactate dehydrogenase activity and ROS and malondialdehyde levels, while superoxide dismutase activity was increased. Additionally, CRYAB, Hsp27, Hsp60 and Hsp70 mRNA levels were upregulated at 3 h (p < 0.01), and protein levels were increased for CRYAB at 0 h (p < 0.05) and 1 h (p < 0.01), and for Hsp70 at 3 and 5 h (p < 0.01). Thus, pre-treatment with vitamin C or vitamin C-Na might protect H9C2 cells against heat damage by enhancing the antioxidant ability and upregulating CRYAB and Hsp70.

BGP-15 improves contractile function of regenerating soleus muscle

This study investigated the effect of the heat shock protein inducer O-[3-piperidino-2-hydroxy-1-propyl]-nicotinic amidoxime (BGP-15) on the morphology and contractile function of regenerating soleus muscles from mice. Cryolesioned soleus muscles from young mice treated daily with BGP-15 (15 mg/Kg) were evaluated on post-cryolesion day 10. At this time point, there was a significant decrease in the cross-sectional area of regenerating myofibers, maximal force, specific tetanic force, and fatigue resistance of regenerating soleus muscles. BGP-15 did not reverse the decrease in myofiber cross-sectional area but effectively prevented the reduction in tetanic force and fatigue resistance of regenerating muscles. In addition, BGP-15 treatment increased the expression of embryonic myosin heavy chain (e-MyHC), MyHC-II and MyHC-I in regenerating muscles. Although BGP-15 did not alter voltage dependent anion-selective channel 2 (VDAC2) expression in cryolesioned muscles, it was able to increase inducible 70-kDa heat shock protein (HSP70) expression. Our results suggest that BGP-15 improves strength recovery in regenerating soleus muscles by accelerating the re-expression of adult MyHC-II and MyHC-I isoforms and HSP70 induction. The beneficial effects of BGP-15 on the contractile function of regenerating muscles reinforce the potential of this molecule to be used as a therapeutic agent.

Overexpression of MCM6 predicts poor survival in patients with glioma

Minichromosome maintenance proteins (MCMs) play an essential role in DNA replication and other cellular activities. However, their expression levels and clinical value in glioma are unclear. In the present study, we analyzed the relationship between MCM mRNA expression and clinical parameters in 325 gliomas and found that MCM6 presented high expression and was associated with poor survival. Immunohistochemistry analysis of an independent data set of 423 glioma tissues confirmed the overexpression of MCM6 protein, especially in glioblastomas with shorter overall survival. Importantly, a combination of MCM6 overexpression with IDH1 mutation further improved the prediction of the prognosis of glioblastomas. Patients with IDH1 mutation and low MCM6 expression exhibited the longest survival, whereas those with high MCM6 expression and wild-type IDH1 showed the shortest. Collectively, our observation indicates that MCM6 is a novel potential biomarker for predicting poor prognosis of the patients with glioma.