Heat stress induced apoptosis is triggered by transcription-independent p53, Ca(2+) dyshomeostasis and the subsequent Bax mitochondrial translocation

Glutamate rescues heat stress-induced apoptosis of Sertoli cells by enhancing the activity of antioxidant enzymes and activating the Trx1-Akt pathway in vitro

Heat stress reduces the number of Sertoli cells, which is closely related to an imbalanced redox status. Glutamate functions to maintain the equilibrium of redox homeostasis. However, the role of glutamate in heat treated Sertoli cells remains unclear. Herein, Sertoli cells from 3-week-old piglets were treated at 44 °C for 30 min (heat stress). Glutamate levels increased significantly following heat stress treatment, followed by a gradual decrease during recovery, while glutathione (GSH) showed a gradual increase. The addition of exogenous glutamate (700 μM) to Sertoli cells before heat stress significantly reduced the heat stress-induced apoptosis rate, mediated by enhanced levels of antioxidant substances (superoxide dismutase (SOD), total antioxidant capacity (TAC), and GSH) and reduced levels of oxidative substances (reactive oxygen species (ROS) and malondialdehyde (MDA)). Glutamate addition to Sertoli cells before heat stress upregulated the levels of glutamate-cysteine ligase, modifier subunit (Gclm), glutathione synthetase (Gss), thioredoxin (Trx1) and B-cell leukemia/lymphoma 2 (Bcl-2), and the ratio of phosphorylated Akt (protein kinase B)/total Akt. However, it decreased the levels of Bcl2-associated X protein (Bax) and cleaved-caspase 3. Addition of the inhibitor of glutaminase (Gls1), Bptes (Bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide, 30 μM)to Sertoli cells before heat stress reversed these effects. These results inferred that glutamate rescued heat stress-induced apoptosis in Sertoli cells by enhancing activity of antioxidant enzymes and activating the Trx1-Akt pathway. Thus, glutamate supplementation might represent a novel strategy to alleviate the negative effect of heat stress.

Impact of rising temperature on physiological and biochemical alterations that affect the viability of blood cells in American bullfrog crossbreeds

The study aimed to examine the impact of increasing environmental temperatures on physiological changes, oxidative stress, nitric oxide production, total antioxidant capacity, and blood cell viability in American bullfrog crossbreeds. Frogs and frog blood cells were exposed to temperature ranges of 25-33 °C and 25-37 °C, respectively. Physiological parameters (body temperature, pulse rate, ventilation rate, and oxygen saturation) and biochemical parameters (total antioxidant power, hydrogen peroxide, malondialdehyde, nitric oxide, and mitochondrial activity) were measured at every 2 °C increment. Results showed that body temperature rose with increased environmental temperature (P < 0.05). Pulse rates at 33 °C were higher than those at 25-31 °C (P < 0.05). Ventilation rates at 31 °C exceeded those at 25 °C and 27 °C (P < 0.05). Oxygen saturation levels remained stable at 25-33 °C (P > 0.05). Total antioxidant power at 25 °C was greater than at 27-37 °C (P < 0.05). Hydrogen peroxide levels at 27 °C were higher compared to 25 °C and 31-37 °C (P < 0.05). Malondialdehyde levels at 25-33 °C were higher than at 35 °C and 37 °C (P < 0.05). Nitric oxide levels at 37 °C were higher than at 25-33 °C (P < 0.05), and at 35 °C were higher than at 25-31 °C (P < 0.05). Blood cell viability at 25-31 °C was higher than at 37 °C (P < 0.05). These results suggest that at an environmental temperature of 33 °C, the frogs' body temperature approached 31 °C or higher, and were likely to be harmful to the frogs. Finally, the environmental temperature that caused frog blood cell death was 37 °C.

Vitamin C Alleviates the Negative Effects of Heat Stress on Reproductive Processes by Regulating Amino Acid Metabolism in Granulosa Cells

Heat stress-induced biochemical alterations in ovarian follicles compromise the function of granulosa cells (GCs) and the developmental competence of oocytes. Summer heat stress can have a far-reaching negative impact on overall fertility and reproductive success. Together with the heat stress, the rise of assisted reproductive technologies (ART), potential confounding hazards of in vitro handling and the absence of systemic body support in ART makes it imperative to study the heat stress ameliorative effects of vitamin C under in vitro conditions. Using in vitro heat stress treatment of 43 °C for two hours in bovine GCs, we studied the effects of vitamin C on cell growth, oxidative stress, apoptosis and cell cycle progression together with a comprehensive metabolomics profiling. This study investigates the molecular milieu underlying the vitamin C (VC)-led alleviation of heat-related disruptions to metabolic processes in bovine GCs. The supplementation of VC ameliorated the detrimental effects of heat stress by reducing oxidative stress and apoptosis while restoring cell proliferation. Normal cell function restoration in treated GCs was demonstrated through the finding of significantly high levels of progesterone. We observed a shift in the metabolome from biosynthesis to catabolism, mostly dominated by the metabolism of amino acids (decreased tryptophan, methionine and tyrosine) and the active TCA cycle through increased Succinic acid. The Glutathione and tryptophan metabolism were important in ameliorating the inflammation and metabolism nexus under heat stress. Two significant enzymes were identified, namely tryptophan 2,3-dioxygenase (TDO2) and mitochondrial phenylalanyl-tRNA synthetase (FARS2). Furthermore, our findings provide insight into the significance of B-complex vitamins in the context of heat stress during VC supplementation. This study underscores the importance of VC supplementation in heat stress and designates multiple metabolic intervention faucets in the context of ameliorating heat stress and enhancing reproductive efficiency.

DNAJA1‑knockout alleviates heat stroke‑induced endothelial barrier disruption via improving thermal tolerance and suppressing the MLCK‑MLC signaling pathway

Endothelial barrier disruption plays a key role in the pathophysiology of heat stroke (HS). Knockout of DNAJA1 (DNAJA1‑KO) is thought to be protective against HS based on a genome‑wide CRISPR‑Cas9 screen experiment. The present study aimed to illustrate the function of DNAJA1‑KO against HS in human umbilical vein endothelial cells. DNAJA1‑KO cells were infected using a lentivirus to investigate the role of DNAJA1‑KO in HS‑induced endothelial barrier disruption. It was shown that DNAJA1‑KO could ameliorate decreased cell viability and increased cell injury, according to the results of Cell Counting Kit‑8 and lactate dehydrogenase assays. Moreover, HS‑induced endothelial cell apoptosis was inhibited by DNAJA1‑KO, as indicated by Annexin V‑FITC/PI staining and cleaved‑caspase‑3 expression using flow cytometry and western blotting, respectively. Furthermore, the endothelial barrier function, as measured by transepithelial electrical resistance and FITC‑Dextran, was sustained during HS. DNAJA1‑KO was not found to have a significant effect on the expression and distribution of cell junction proteins under normal conditions without HS. However, DNAJA1‑KO could effectively protect the HS‑induced decrease in the expression and distribution of cell junction proteins, including zonula occludens‑1, claudin‑5, junctional adhesion molecule A and occludin. A total of 4,394 proteins were identified using proteomic analysis, of which 102 differentially expressed proteins (DEPs) were activated in HS‑induced wild‑type cells and inhibited by DNAJA1‑KO. DEPs were investigated by enrichment analysis, which demonstrated significant enrichment in the 'calcium signaling pathway' and associations with vascular‑barrier regulation. Furthermore, the 'myosin light‑chain kinase (MLCK)‑MLC signaling pathway' was proven to be activated by HS and inhibited by DNAJA1‑KO, as expected. Moreover, DNAJA1‑KO mice and a HS mouse model were established to demonstrate the protective effects on endothelial barrier in vivo. In conclusion, the results of the present study suggested that DNAJA1‑KO alleviates HS‑induced endothelial barrier disruption by improving thermal tolerance and suppressing the MLCK‑MLC signaling pathway.

Induction of fat apoptosis by a combination of synchronized radiofrequency and HIFEM technology: Human histology study

PURPOSE

With the growing demand for more effective fat reduction techniques, a combination of synchronized radiofrequency (RF) and HIFEM has been introduced. Preceding studies evidenced the ability of RF+HIFEM to maintain the fat tissue temperature at the levels necessary for adipocyte apoptosis while documenting the induced changes to the fat tissue during the several weeks after the treatment. This study aims to demonstrate the induction of apoptosis by RF+HIFEM technology in the early stages through the assessment of caspase-3 protein, one of the apoptosis-executing proteases.

DESIGN

In this two-arm, single-center, randomized trial, nine human subjects were enrolled and assigned into two groups, either the active group (N = 6) treated with both RF+HIFEM set at the highest tolerated levels or the sham group (N = 3) treated with 5% of the maximum RF+HIFEM power, serving as a control. All patients were scheduled to undergo one treatment visit of the abdominal area, two follow-up visits at 8 and 24 h, and one safety visit 7 days after the treatment. A punch biopsy (5 mm in diameter, approximately 10 mm in depth) was obtained from the abdominal area at the baseline and consecutive follow-up visits. Samples were fixed, and cut into 5 μm thick slices, and immunohistochemical staining was used to visualize the Caspase-3, revealing the adipocyte nuclei where apoptosis processes are in progress.

FINDINGS

Documented findings suggest that the temperature threshold of 43-45°C is required to initiate fat apoptosis and consequent reduction in adipocyte number was achieved during the combined treatment with RF+HIFEM. The active group showed an elevated ratio of positively stained nuclei versus all adipocyte nuclei found on the evaluated slices-referred to as the apoptotic index (AI). The AI significantly (p < 0.001) increased at both 8 h (47.01 ± 10.56%) and 24 h (43.58 ± 6.35%) posttreatment. The Sham group showed no significant change in the AI (p > 0.05). No adverse events or side effects related to the treatments were observed.

SUMMARY

This study supports previously published evidence on fat reduction after RF+HIFEM treatment, documenting the safe initiation of adipocyte programmed cell death posttreatment.

Hyperthermia-induced changes in leukocyte survival and phagocytosis: a comparative study in bovine and buffalo leukocytes

Heat stress negatively affects health, welfare, and livestock productivity by impairing immune function, increasing disease incidence. In recent years, there has been increasing interest in understanding the immune system of water buffalo due to the growing economic impact of this species for the high quality and nutritional value of buffalo milk. While there are common responses across bovine and buffalo species, there are also some species-specific variations in the physiological responses to heat stress, mainly attributed to differences in metabolism and heat dissipation efficiency. At cellular level, the exposure to thermal stress induces several anomalies in cell functions. However, there is limited knowledge about the differential response of bovine and buffalo leucocytes to early and late exposure to different degrees of thermal exposure. The aim of this study was to compare the in vitro effect of hyperthermia on apoptosis and phagocytosis in leukocytes from bovine and buffalo species. For this, whole blood samples of six bovines and nine buffaloes were incubated at 39°C (mimicking normothermia condition) or 41°C (mimicking heat stress condition) for 1, 2, and 4 h. Two flow cytometric assays were then performed to evaluate apoptosis and determine functional capacity of phagocytic cells (neutrophils and monocytes). The results showed that the viability of bovine and buffalo leukocytes was differently affected by temperature and time of in vitro exposure. A higher percentage of apoptotic leukocytes was observed in bovines than in buffaloes at 39°C (3.19 vs. 1.51, p < 0.05) and 41°C (4.01 vs. 1.69, p < 0.05) and for all incubation time points (p < 0.05). In contrast, no difference was observed in the fraction of necrotic leukocytes between the two species. In both species, lymphocytes showed the highest sensitivity to hyperthermia, showing an increased apoptosis rates along with increased incubation time. In bovine, apoptotic lymphocytes increased from 5.79 to 12.7% at 39°C (p < 0.05), in buffalo, this population increased from 1.50 to 3.57% at 39°C and from 2.90 to 4.99% at 41°C (p < 0.05). Although no significant differences were found between the two species regarding the percentage of phagocytic neutrophils, lower phagocytosis capacity values (MFI, mean fluorescence intensity) were found in bovines compared with buffaloes at 41°C (27960.72 vs. 53676.45, p > 0.05). However, for monocytes, the differences between species were significant for both phagocytosis activity and capacity with lower percentages of bovine phagocytic monocytes after 2 h at 39°C and after 1 h at 41°C. The bovine monocytes showed lower MFI values for all temperature and time variations than buffaloes (37538.91 vs. 90445.47 at 39°C and 33752.91 vs. 70278.79 at 41°C, p < 0.05). In conclusion, the current study represents the first report on the comparative analysis of the effect of in vitro heat stress on bovine and buffalo leukocyte populations, highlighting that the leukocytes of buffalo exhibit relatively higher thermal adaptation than bovine cells.

Chlorogenic acid ameliorates the heat stress-induced impairment of porcine Sertoli cells by suppressing oxidative stress and apoptosis

Sertoli cells are an important type of somatic cell in the testis that are in direct contact with spermatogonia in vivo and play an important role in the process of spermatogenesis. Chlorogenic acid (CGA) plays a pivotal role in the regulation of the mammalian cell heat stress response. For example, CGA treatment protects porcine oocytes from heat stress-induced apoptosis and prevents reduced embryo quality. However, the role of CGA treatment in protecting porcine testicular Sertoli cells against heat-induced damage has rarely been studied. This study aimed to identify the protective effects of CGA on oxidative stress and apoptosis in Sertoli cells under heat stress. The present results demonstrated that the addition of CGA significantly inhibited the accumulation of reactive oxygen species (ROS) and apoptosis in Sertoli cells induced by heat stress and decreased the expression of CASP3 protein and the BAX/BCL-2 protein ratio. CGA pretreatment also prevented the heat stress-induced reductions in the mitochondrial membrane potential, PCNA protein expression, and SOD and CAT activities. Moreover, CGA treatment reversed S phase cell cycle arrest and increased the HSP70 protein expression levels. Overall, these results suggest that oxidative damage participates in the inhibition of the proliferation of Sertoli cells and the increase in their apoptosis induced by heat stress, and the protective effects of CGA treatment on Sertoli cells under heat stress provide a theoretical basis for preventing heat stress injury in animals.

Role of intrinsic apoptosis in environmental exposure health outcomes

Environmental exposures are linked to diseases of high public health concern, including cancer, neurodegenerative disorders, and autoimmunity. These diseases are caused by excessive or insufficient cell death, prompting investigation of mechanistic links between environmental toxicants and dysregulation of cell death pathways, including apoptosis. This review describes how legacy and emerging environmental exposures target the intrinsic apoptosis pathway to potentially drive pathogenesis. Recent discoveries reveal that dynamic regulation of apoptosis may heighten the vulnerability of healthy tissues to exposures in children, and that apoptotic signaling can guide immune responses, tissue repair, and tumorigenesis. Understanding how environmental toxicants dysregulate apoptosis will uncover opportunities to deploy apoptosis-modulating agents for the treatment or prevention of exposure-linked diseases.

Association of transient mitochondrial functional impairment with acute heat exposure in children from Muzaffarpur region of Bihar, India

Over the past several years, the Muzaffarpur district of Bihar (India) has witnessed recurrent outbreaks of acute encephalitis illness of unknown etiology, called acute encephalitis syndrome (AES) among young children, especially during the peak-summer season. Pesticide exposure, viral encephalitis, and litchi toxin intake have all been postulated as potential sources of the ailment. However, no conclusive etiology for AES has been identified in the affected children. During recent rounds of the outbreak, metabolic abnormalities have been documented in these children, and a direct correlation was observed between higher environmental temperature during the peak-summer month and AES caseload. The clinical and metabolic profiles of these children suggested the possible involvement of mitochondrial dysfunction during heat stress as one of the several contributory factors leading to multisystem metabolic derangement. The present study observed that mitochondrial function parameters such as cell death, mitochondrial membrane potential, oxidative stress, and mitochondrial pathway-related gene expression in peripheral blood mononuclear cells (PBMCs) isolated from children were affected in peak-summer when compared to post-summer months. Similar observations of mitochondrial function parameters along with impaired bioenergetic parameters were demonstrated in the heat-exposed model of PBMCs isolated from healthy adult individuals. In conclusion, the results suggested that there is an association of transient mitochondrial dysfunction when exposed to sustained heat during the summer months. One may consider mitochondrial dysfunction as one of the important factors leading to an outbreak of AES among the children from affected regions though this needs to be substantiated with further studies.

Insect Peptide CopA3 Mitigates the Effects of Heat Stress on Porcine Muscle Satellite Cells

Heat stress inhibits cell proliferation as well as animal production. Here, we aimed to demonstrate that 9-mer disulfide dimer peptide (CopA3) supplementation stabilizes porcine muscle satellite cell (PMSC) proliferation and heat shock protein (HSP) expression at different temperatures. Therefore, we investigated the beneficial effects of CopA3 on PMSCs at three different temperatures (37, 39, and 41 °C). Based on temperature and CopA3 treatment, PMSCs were divided into six different groups including treatment and control groups for each temperature. Cell viability was highest with 10 µg/mL CopA3 and decreased as the concentration increased in a dose-dependent manner. CopA3 significantly increased the cell viability at all temperatures at 24 and 48 h. It significantly decreased apoptosis compared to that in the untreated groups. In addition, it decreased the apoptosis-related protein, Bcl-2-associated X (BAX), expression at 41 °C. Notably, temperature and CopA3 had no effects on the apoptosis-related protein, caspase 3. Expression levels of HSP40, HSP70, and HSP90 were significantly upregulated, whereas those of HSP47 and HSP60 were not affected by temperature changes. Except HSP90, CopA3 did not cause temperature-dependent changes in protein expression. Therefore, CopA3 promotes cell proliferation, inhibits apoptosis, and maintains stable HSP expression, thereby enhancing the heat-stress-tolerance capacity of PMSCs.

Endothelial glycocalyx injury is involved in heatstroke-associated coagulopathy and protected by N-acetylcysteine

Introduction

Damage to endothelial glycocalyx (EGCX) can lead to coagulation disorders in sepsis. Heat stroke (HS) resembles sepsis in many aspects; however, it is unclear whether EGCX injury is involved in its pathophysiology. The purpose of this study was to examine the relationship between the damage of EGCX and the development of coagulation disorders during HS.

Methods

We retrospectively collected 159 HS patients and analyzed coagulation characteristics and prognosis of HS patients with or without disseminated intravascular coagulation (DIC). We also replicated a rat HS model and measured coagulation indexes, pulmonary capillary EGCX injury in HS rats. Finally, we evaluated the effect of the antioxidant N-acetylcysteine (NAC) on HS-initiated EGCX injury and coagulation disorders.

Results

Clinical data showed that HS patients complicated with DIC had a higher risk of death than HS patients without DIC. In a rat HS model, we found that rats subjected to heat stress developed hypercoagulability and platelet activation at the core body temperature of 43°C, just before the onset of HS. At 24 h of HS, the rats showed a consumptive hypo-coagulation state. The pulmonary capillary EGCX started to shed at 0 h of HS and became more severe at 24 h of HS. Importantly, pretreatment with NAC substantially alleviated EGCX damage and reversed the hypo-coagulation state in HS rats. Mechanically, HS initiated reactive oxidative species (ROS) generation, while ROS could directly cause EGCX damage. Critically, NAC protected against EGCX injury by attenuating ROS production in heat-stressed or hydrogen peroxide (H2O2)-stimulated endothelial cells.

Discussion

Our results indicate that the poor prognosis of HS patients correlates with severe coagulation disorders, coagulation abnormalities in HS rats are associated with the damage of EGCX, and NAC improves HS-induced coagulopathy, probably through its protection against EGCX injury by preventing ROS generation.

Effects of Cooling Interventions with Different Target Temperatures on Heat Stroke Rats

Purpose

To investigate the optimal target temperature of cooling intervention in heat stroke (HS) rats and explore the potential mechanisms of cooling intervention in alleviating heat stroke-induced damage.

Materials and Methods

A total of 32 Sprague-Dawley rats were randomly divided into 4 groups (n=8/group), including control, HS[core body temperature (Tc)], HS(Tc-1°C) and HS(Tc+1°C) group. Heat stroke model was established in rats of HS(Tc), HS(Tc-1°C) and HS(Tc+1°C) group. Rats in HS(Tc) group were cooled to baseline core body temperature after establishing heat stroke model, HS(Tc-1°C) group to baseline core body temperature minus 1°C and HS(Tc+1°C) group to baseline core body temperature plus 1°C. We compared the histopathological changes of lung, liver and renal tissue, as well as cell apoptosis and expression of critical proteins in phosphatidylinositol 3´-kinase (PI3K)/Akt signaling pathway.

Results

Heat stroke caused the histopathological damage and cell apoptosis of lung, liver and renal tissue, which could be alleviated by cooling intervention to a certain extent. Notably, HS(Tc+1°C) group demonstrated a better effect on alleviating cell apoptosis although the differences were not significant. Heat stroke lead to the elevated expression of p-Akt, which subsequently induced the elevated expression of Caspase-3 and Bax, as well as the decreased expression of Bcl-2. Cooling intervention could reverse this trend. Notably, the expression level of Bax in lung tissue of HS(Tc+1°C) group was significantly lower than that of HS(Tc) and HS(Tc-1°C) group.

Conclusion

The mechanisms of cooling intervention in alleviating heat stroke-induced damage were associated with the expression changes of p-Akt, Caspase-3, Bax and Bcl-2. The better effect of Tc+1°C might be associated with low expression of Bax.

Heat Stress-Induced Intestinal Barrier Impairment: Current Insights into the Aspects of Oxidative Stress and Endoplasmic Reticulum Stress

Heat stress (HS) occurs when the sensible temperature of animals exceeds their thermoregulatory capacity, a condition that exerts a detrimental impact on health and growth. The intestinal tract, as a highly sensitive organ, has been shown to respond to HS by exhibiting mucosal injury, intestinal leakage, and disturbances in the gut microbiota. Oxidative stress and endoplasmic reticulum stress (ERS) are both potential outcomes of long-term exposure to high temperatures and have been linked to apoptosis, autophagy, and ferroptosis. In addition, HS alters the composition of the gut microbiota accompanied by changed levels of bacterial components and metabolites, rendering the gut more vulnerable to stress-related injury. In this review, we present recent advances in mechanisms of oxidative stress-associated ERS in response to HS, which is destructive to intestinal barrier integrity. The involvement of autophagy and ferroptosis in ERS was highlighted. Further, we summarize the relevant findings regarding the engagement of gut microbiota-derived components and metabolites in modulation of intestinal mucosal injury induced by HS.

Apoptosis-inducing factor-like protein-mediated stress and metronidazole-responsive programmed cell death pathway in Entamoeba histolytica

Apoptosis-inducing factor (AIF) is the major component of the caspase-independent cell death pathway that is considered to be evolutionarily ancient. Apoptosis is generally evolved with multicellularity as a prerequisite for the elimination of aged, stressed, or infected cells promoting the survival of the organism. Our study reports the presence of a putative AIF-like protein in Entamoeba histolytica, a caspase-deficient primitive protozoan, strengthening the concept of occurrence of apoptosis in unicellular organisms as well. The putative cytoplasmic EhAIF migrates to the nucleus on receiving stresses that precede its binding with DNA, following chromatin degradation and chromatin condensation as evident from both in vitro and in vivo experiments. Down-regulating the EhAIF expression attenuates the apoptotic features of insulted cells and increases the survival potency in terms of cell viability and vitality of the trophozoites, whereas over-expression of the EhAIF effectively enhances the phenomena. Interestingly, metronidazole, the most widely used drug for amoebiasis treatment, is also potent to elicit similar AIF-mediated cell death responses like other stresses indicating the AIF-mediated cell death could be the probable mechanism of trophozoite-death by metronidazole treatment. The occurrence of apoptosis in a unicellular organism is an interesting phenomenon that might signify the altruistic death that overall improves the population health.

ZBP1 and heatstroke

Heatstroke, which is associated with circulatory failure and multiple organ dysfunction, is a heat stress-induced life-threatening condition characterized by a raised core body temperature and central nervous system dysfunction. As global warming continues to worsen, heatstroke is expected to become the leading cause of death globally. Despite the severity of this condition, the detailed mechanisms that underlie the pathogenesis of heatstroke still remain largely unknown. Z-DNA-binding protein 1 (ZBP1), also referred to as DNA-dependent activator of IFN-regulatory factors (DAI) and DLM-1, was initially identified as a tumor-associated and interferon (IFN)-inducible protein, but has recently been reported to be a Z-nucleic acid sensor that regulates cell death and inflammation; however, its biological function is not yet fully understood. In the present study, a brief review of the main regulators is presented, in which the Z-nucleic acid sensor ZBP1 was identified to be a significant factor in regulating the pathological characteristics of heatstroke through ZBP1-dependent signaling. Thus, the lethal mechanism of heatstroke is revealed, in addition to a second function of ZBP1 other than as a nucleic acid sensor.

Genome-wide sequencing identifies a thermal-tolerance related synonymous mutation in the mussel, Mytilisepta virgata

The roles of synonymous mutations for adapting to stressful thermal environments are of fundamental biological and ecological interests but poorly understood. To study whether synonymous mutations influence thermal adaptation at specific microhabitats, a genome-wide genotype-phenotype association analysis is carried out in the black mussels Mytilisepta virgata. A synonymous mutation of Ubiquitin-specific Peptidase 15 (MvUSP15) is significantly associated with the physiological upper thermal limit. The individuals carrying GG genotype (the G-type) at the mutant locus possess significantly lower heat tolerance compared to the individuals carrying GA and AA genotypes (the A-type). When heated to sublethal temperature, the G-type exhibit higher inter-individual variations in MvUSP15 expression, especially for the mussels on the sun-exposed microhabitats. Taken together, a synonymous mutation in MvUSP15 can affect the gene expression profile and interact with microhabitat heterogeneity to influence thermal resistance. This integrative study sheds light on the ecological importance of adaptive synonymous mutations as an underappreciated genetic buffer against heat stress and emphasizes the importance of integrative studies at a microhabitat scale for evaluating and predicting the impacts of climate change.

Glutamine alleviated heat stress-induced damage of porcine intestinal epithelium associated with the mitochondrial apoptosis pathway mediated by heat shock protein 70

The present study aimed to investigate the effect of glutamine (Gln) addition on the damage of porcine intestinal epithelial cells (IPEC-J2) induced by heat stress (HS). IPEC-J2 cultured in logarithmic growth period in vitro were firstly exposed to 42 °C for 0.5, 1, 2, 4, 6, 8, 10, 12, and 24 h for cell viability and cultured with 1, 2, 4, 6, 8, or 10 mmol Gln per L of culture media for heat shock protein 70 (HSP70) expression to determine the optimal disposal strategy (HS, 42 °C for 12 h and HSP70 expression, 6 mmol/L Gln treatment for 24 h). Then IPEC-J2 cells were divided into three groups: control group (Con, cultured at 37 °C), HS group (HS, cultured at 42 °C for 12 h), and glutamine group (Gln+HS, cultured at 42 °C for 12 h combined with 6 mmol/L Gln treatment for 24 h). The results showed that HS treatment for 12 h significantly decreased the cell viability of IPEC-J2 (P < 0.05) and 6 mmol/L Gln treatment for 12 h increased HSP70 expression (P < 0.05). HS treatment increased the permeability of IPEC-J2, evidenced by the increased fluorescent yellow flux rates (P < 0.05) and the decreased transepithelial electrical resistance (P < 0.05). Moreover, the downregulated protein expression of occludin, claudin-1, and zonula occludens-1 was observed in HS group (P < 0.05), but Gln addition alleviated the negative effects on permeability and the integrity of intestinal mucosal barrier induced by HS (P < 0.05). In addition, HS resulted in the elevations in HSP70 expression, cell apoptosis, cytoplasmic cytochrome c potential expression, and the protein expressions of apoptosis-related factors (apoptotic protease-activating factor-1, cysteinyl aspartate-specific proteinase-3, and cysteinyl aspartate-specific proteinase-9) (P < 0.05); however, the reductions in mitochondrial membrane potential expression and B-cell lymphoma-2 expression were induced by HS (P < 0.05). But Gln treatment attenuated HS-induced adverse effects mentioned above (P < 0.05). Taken together, Gln treatment exhibited protective effects in protecting IPEC-J2 from cell apoptosis and the damaged integrity of epithelial mucosal barrier induced by HS, which may be associated with the mitochondrial apoptosis pathway mediated by HSP70.

Activated AMPK mitigates diabetes-related cognitive dysfunction by inhibiting hippocampal ferroptosis

Clinical and preclinical interest in Type 2 diabetes (T2D)-associated cognitive dysfunction (TDACD) has grown in recent years. However, the precise mechanisms underlying TDACD need to be further elucidated. Ferroptosis was reportedly involved in neurodegenerative diseases and diabetes-related organ injuries; however, its role in TDACD remains elusive. In this study, mice fed with a high-fat-diet combined with streptozotocin (HFD-STZ) were used as a T2D model to assess the role of ferroptosis in cognitive dysfunction. We found that ferroptosis was mainly activated in hippocampal neurons but not in microglia or astrocytes. Accordingly, increased levels of transferrin receptor and decreased levels of ferritin, GPX4, and SLC7A11 were observed in hippocampal neurons. In addition, pre-treatment with liproxstatin-1, a ferroptosis inhibitor, attenuated iron accumulation and oxidative stress response, which resulted in improved cognitive function in the HFD-STZ group. Furthermore, we found that p-AMP-activated protein kinase (AMPK) was decreased in the HFD-STZ group. Pre-treatment with AMPK agonist increased the expression of AMPK and GPX4, but decreased lipocalin 2 (LCN2) in the hippocampus that resulted in improved spatial learning ability in the HFD-STZ group. Taken together, we found that activation of neuronal ferroptosis in the hippocampus contributed to cognitive impairment of HFD-STZ mice. Furthermore, AMPK activation may reduce hippocampal ferroptosis, and consequently improve cognitive performance in diabetic mice.

COPA3 peptide supplementation alleviates the heat stress of chicken fibroblasts

Heat stress inhibits cellular proliferation and differentiation through the production of reactive oxygen species. Under stress conditions, antioxidant drugs promote stable cellular function by reducing the stress level. We sought to demonstrate 9-mer disulfide dimer peptide (COPA3) supplementation stabilizes fibroblast proliferation and differentiation even under heat stress conditions. In our study, fibroblasts were assigned to two different groups based on the temperature, like 38°C group presented as Control - and 43°C group presented as Heat Stress-. Each group was subdivided into two groups depending upon COPA3 treatment, like 38°C + COPA3 group symbolized Control+ and the 43°C + COPA3 group symbolized as Heat Stress+. Heat stress was observed to decrease the fibroblast viability and function and resulted in alterations in the fibroblast shape and cytoskeleton structure. In contrast, COPA3 stabilized the fibroblast viability, shape, and function. Moreover, heat stress and COPA3 were found to have opposite actions with respect to energy production, which facilitates the stabilization of cellular functions by increasing the heat tolerance capacity. The gene expression levels of antioxidant and heat shock proteins were higher after heat stress. Additionally, heat stress promotes the mitogen-activated protein kinase/ extracellular signal-regulated kinase-nuclear factor erythroid 2-related factor 2 (MAPK/ERK-Nrf2). COPA3 maintained the MAPK/ERK-Nrf2 gene expressions that promote stable fibroblast proliferation, and differentiation as well as suppress apoptosis. These findings suggest that COPA3 supplementation increases the heat tolerance capacity, viability, and functional activity of fibroblasts.

Mitochondrial Permeability Transition in Stem Cells, Development, and Disease

The mitochondrial permeability transition (mPT) is a process that permits rapid exchange of small molecules across the inner mitochondrial membrane (IMM) and thus plays a vital role in mitochondrial function and cellular signaling. Formation of the pore that mediates this flux is well-documented in injury and disease but its regulation has also emerged as critical to the fate of stem cells during embryonic development. The precise molecular composition of the mPTP has been enigmatic, with far more genetic studies eliminating molecular candidates than confirming them. Rigorous studies in the recent decade have implicated central involvement of the F₁F_o ATP synthase, or complex V of the electron transport chain, and continue to confirm a regulatory role for Cyclophilin D (CypD), encoded by Ppif, in modulating the sensitivity of the pore to opening. A host of endogenous molecules have been shown to trigger flux characteristic of mPT, including positive regulators such as calcium ions, reactive oxygen species, inorganic phosphate, and fatty acids. Conductance of the pore has been described as low or high, and reversibility of pore opening appears to correspond with the relative abundance of negative regulators of mPT such as adenine nucleotides, hydrogen ion, and divalent cations that compete for calcium-binding sites in the mPTP. Current models suggest that distinct pores could be responsible for differing reversibility and conductance depending upon cellular context. Indeed, irreversible propagation of mPT inevitably leads to collapse of transmembrane potential, arrest of ATP synthesis, mitochondrial swelling, and cell death. Future studies should clarify ambiguities in mPTP structure and reveal new roles for mPT in dictating specialized cellular functions beyond cell survival that are tied to mitochondrial fitness including stem cell self-renewal and fate. The focus of this review is to describe contemporary models of the mPTP and highlight how pore activity impacts stem cells and development.

Novel organic selenium source hydroxy-selenomethionine counteracts the blood-milk barrier disruption and inflammatory response of mice under heat stress

Heat stress (HS) in summer has caused huge economic losses to animal husbandry production recently. When mammary gland is exposed to high temperatures, it will cause blood-milk barrier damage. Hydroxy-selenomethionine (HMSeBA) is a new selenium source with better guarantee of animals' production performance under stress, but whether it has protective effect on heat stress-induced blood-milk damage is still unclear. We established mammary epithelial cells and mice heat stress injury models to fill this research gap, and hope to provide theoretical basis for using HMSeBA to alleviate heat stress damage mammary gland. The results showed that (1) Heat stress significantly decreases in vitro transepithelial electrical resistance (TEER) and cell viability (P < 0.01), and significantly decreases clinical score, histological score, and total alveoli area of mice mammary gland tissue (P < 0.01). (2) HMSeBA significantly increases TEER and fluorescein sodium leakage of HS-induced monolayer BMECs (P < 0.01), significantly improves the milk production and total area of alveoli (P < 0.01), and reduces clinical score, histological score, mRNA expression of heat stress-related proteins, and inflammatory cytokines release of heat-stressed mice (P < 0.01). (3) HMSeBA significantly improves tight junction structure damage, and significantly up-regulated the expression of tight junction proteins (ZO-1, claudin 1, and occludin) as well as signal molecules PI3K, AKT, and mTOR (P < 0.01) in heat-stressed mammary tissue. (4) HMSeBA significantly increases glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and superoxide dismutase release (SOD) (P < 0.01) and significantly reduce malondialdehyde (MDA) expression (P < 0.01) in heat-stressed mammary tissue. In conclusion, this study implemented heat-stressed cell and mice model and showed that HMSeBA significantly regulate antioxidant capacity, inhibited inflammation, and regulate tight junction proteins expression in blood-milk barrier via PI3K/AKT/mTOR signaling pathway, so as to alleviate mammary gland damage and ensure its structure and function integrity.

Identification of Novel mRNA Isoforms Associated with Acute Heat Stress Response Using RNA Sequencing Data in Sprague Dawley Rats

The molecular mechanisms underlying heat stress tolerance in animals to high temperatures remain unclear. This study identified the differentially expressed mRNA isoforms which narrowed down the most reliable DEG markers and molecular pathways that underlie the mechanisms of thermoregulation. This experiment was performed on Sprague Dawley rats housed at 22 °C (control group; CT), and three acute heat-stressed groups housed at 42 °C for 30 min (H30), 60 min (H60), and 120 min (H120). Earlier, we demonstrated that acute heat stress increased the rectal temperature of rats, caused abnormal changes in the blood biochemical parameters, as well as induced dramatic changes in the expression levels of genes through epigenetics and post-transcriptional regulation. Transcriptomic analysis using RNA-Sequencing (RNA-Seq) data obtained previously from blood (CT and H120), liver (CT, H30, H60, and H120), and adrenal glands (CT, H30, H60, and H120) was performed. The differentially expressed mRNA isoforms (DEIs) were identified and annotated by the CLC Genomics Workbench. Biological process and metabolic pathway analyses were performed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. A total of 225, 5764, and 4988 DEIs in the blood, liver, and adrenal glands were observed. Furthermore, the number of novel differentially expressed transcript lengths with annotated genes and novel differentially expressed transcript with non-annotated genes were 136 and 8 in blood, 3549 and 120 in the liver, as well as 3078 and 220 in adrenal glands, respectively. About 35 genes were involved in the heat stress response, out of which, Dnaja1, LOC680121, Chordc1, AABR07011951.1, Hsp90aa1, Hspa1b, Cdkn1a, Hmox1, Bag3, and Dnaja4 were commonly identified in the liver and adrenal glands, suggesting that these genes may regulate heat stress response through interactions between the liver and adrenal glands. In conclusion, this study would enhance our understanding of the complex underlying mechanisms of acute heat stress, and the identified mRNA isoforms and genes can be used as potential candidates for thermotolerance selection in mammals.

Protective Effect of Manganese on Apoptosis and Mitochondrial Function of Heat-Stressed Primary Chick Embryonic Myocardial Cells

Heat stress, as a kind of oxidative stress, induces cell apoptosis. Apoptosis is a form of programmed cell death, and mitochondria play an important role in apoptosis. Manganese (Mn) has an antioxidant capacity by enhancing the activity of manganese superoxide dismutase (MnSOD). To investigate the potential effect of Mn on heat stress-induced apoptosis and mitochondrial function, we examined crucial related factors in the context of heat stress using primary chick embryonic myocardial cells pretreated with Mn for 24 h. The results showed that Mn restored the heat stress-induced decrease in cell viability and reduced the activities of caspase-3 (P < 0.05). The repression of the Δψm and intracellular ATP content caused by heat stress was reversed dramatically in the Mn pretreatment group (P < 0.05). Additionally, Mn inhibited heat stress-induced mitochondrial fission, as shown by decreased mitochondrial fission-related protein dynamin-related protein 1 (Drp1) expression and increased mitochondrial fusion-related protein optic atrophy 1 (Opa1) and mitofusin 1 (Mfn1) (P < 0.05) in primary chick embryonic myocardial cells. It was concluded that Mn attenuates the mitochondrial-mediated apoptosis pathway and sustains mitochondrial structure and function under heat stress in primary chick embryonic myocardial cells.

Investigation of the Gastroprotective Effect of Betaine-Homocysteine Homeostasis on Oxidative Stress, Inflammation and Apoptosis in Ethanol-Induced Ulcer Model

Background: There is a growing interest in the use of natural compounds for the treatment of gastric ulcers. The multifunctional roles of betaine in various diseases make this natural substance a favorable pre-drug for ulcer treatment. This study aims to determine the competence of betaine in gastroprotection against ethanol-induced damage and to explore underlying mechanisms considering its effects on liver and kidney activity and blood parameters.Methods: Wistar albino rats were orally treated with vehicle (distilled water) or betaine (250 mg/kg) for twenty-one days and then ulcer formation was induced by ingestion of 75% ethanol. Gastric mucosal damage was evaluated by gross examination and histopathological analysis. Homocysteine levels, lipid peroxidation, total antioxidant status (TAS), total oxidant status (TAS), antioxidant enzymes and pro-inflammatory and anti-inflammatory cytokines levels were assessed by enzyme-linked immunosorbent assay (ELISA) or immunohistochemistry. Furthermore, routine biochemical tests were performed and hematological parameters were analyzed.Results: Betaine ameliorated any gastric mucosal damage and reduced homocysteine levels significantly. The TOS and malondialdehyde (MDA) levels were decreased while the TAS, glutathione (GSH) levels and catalase (CAT) activity were increased upon the betaine treatment. Betaine reduced apoptosis by regulating Bax and Bcl-2 levels, however, it did not alter inflammatory mediators. Additionally, betaine improved serum potassium (K⁺) and blood urea nitrogen (BUN) levels, whereas it increased alanine aminotransferase (ALT) levels and impaired hematological parameters.Conclusions: Altogether, these data illustrated that betaine exhibits a gastroprotective effect against ulcers through the homocysteine pathway by modulating oxidative stress in the gastric tissue; however, its systemic effects should not be ignored.

Manganese Mitigates Heat Stress-Induced Apoptosis by Alleviating Endoplasmic Reticulum Stress and Activating the NRF2/SOD2 Pathway in Primary Chick Embryonic Myocardial Cells

Heat stress leads to oxidative stress and induces apoptosis in various cells. Endoplasmic reticulum (ER) stress is an important apoptosis pathway. Manganese (Mn) has been shown to enhance the activity of manganese superoxide dismutase (MnSOD). To explore the potential effect of Mn on ER stress and apoptosis induced by heat stress, we examined crucial factors associated with heat stress, ER stress, and apoptosis in cultured primary chick embryonic myocardial cells that had been pretreated with 20 μM Mn for 24 h and then subjected to 4 h of heat stress. The results showed that Mn decreased (P < 0.05) heat stress-induced reactive oxygen species (ROS) production and exerted antiapoptotic effects by increasing MnSOD enzymatic activity. The heat stress-induced accumulation of intracellular calcium was dramatically reduced (P < 0.05). Mn treatment significantly decreased (P < 0.05) the expression levels of the apoptosis-related gene Bax and ER stress markers glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in primary chick embryonic myocardial cells. Additionally, Mn reduced oxidative stress by activating the nuclear factor E2-related factor 2 (NRF2)/SOD2 signaling pathway. Taken together, our findings indicate that Mn attenuates heat stress-induced apoptosis by inhibiting ROS generation, intracellular calcium accumulation, and the ER stress pathway and activating the NRF2/SOD2 signaling pathway to protect myocardial cells from oxidative stress during chick embryonic development.

Transcriptome Reveals Granulosa Cells Coping through Redox, Inflammatory and Metabolic Mechanisms under Acute Heat Stress

Heat stress affects granulosa cells (GCs) and the ovarian follicular microenvironment, causing poor oocyte developmental competence and fertility. This study aimed to investigate the physical responses and global transcriptomic changes in bovine GCs to acute heat stress (43 °C for 2 h) in vitro. Heat-stressed GCs exhibited transient proliferation senescence and resumed proliferation at 48 h post-stress, while post-stress immediate culture-media change had a relatively positive effect on proliferation resumption. Increased accumulation of reactive oxygen species and apoptosis was observed in the heat-stress group. In spite of the upregulation of inflammatory (CYCS, TLR2, TLR4, IL6, etc.), pro-apoptotic (BAD, BAX, TNFSF9, MAP3K7, TNFRSF6B, FADD, TRADD, RIPK3, etc.) and caspase executioner genes (CASP3, CASP8, CASP9), antioxidants and anti-apoptotic genes (HMOX1, NOS2, CAT, SOD, BCL2L1, GPX4, etc.) were also upregulated in heat-stressed GCs. Progesterone and estrogen hormones, along with steroidogenic gene expression, declined significantly, in spite of the upregulation of genes involved in cholesterol synthesis. Out of 12,385 differentially expressed genes (DEGs), 330 significant DEGs (75 upregulated, 225 downregulated) were subjected to KEGG functional pathway annotation, gene ontology enrichment, STRING network analyses and manual querying of DEGs for meaningful molecular mechanisms. High inflammatory response was found to be responsible for oxidative-stress-mediated apoptosis of GCs and nodes towards the involvement of the NF-κB pathway and repression of the Nrf2 pathway. Downregulation of MDM4, TP53, PIDD1, PARP3, MAPK14 and MYC, and upregulation of STK26, STK33, TGFB2, CDKN1A and CDKN2A, at the interface of the MAPK and p53 signaling pathway, can be attributed to transient cellular senescence and apoptosis in GCs. The background working of the AMPK pathway through upregulation of AKT1, AMPK, SIRT1, PYGM, SLC2A4 and SERBP1 genes, and downregulation of PPARGCIA, IGF2, PPARA, SLC27A3, SLC16A3, TSC1/2, KCNJ2, KCNJ16, etc., evidence the repression of cellular transcriptional activity and energetic homeostasis modifications in response to heat stress. This study presents detailed responses of acute-heat-stressed GCs at physical, transcriptional and pathway levels and presents interesting insights into future studies regarding GC adaptation and their interaction with oocytes and the reproductive system at the ovarian level.

Experimental hyperthermia: expression of proteins involved in the regulation of ovarian corpus luteum apoptosis in the acute and recovery periods

Background.Heat shock effects can initiate apoptosis of oocytes and corpus luteum cells in mammalian ovaries. During folliculogenesis, follicular apoptosis is regulated by Bcl-2 and BAX proteins which are key effectors of granular cell death. Mechanisms of disruption of the ovarian corpus luteum development under heat stress remain largely unclear.

Aim of the research: to identify the expression features of anti-apoptotic Bad and proapoptotic Bcl-2 proteins in the rat ovarian luteocytes in the acute (by day 3) and recovery (by days 7 and 14) periods after a single exposure of experimental hyperthermia (EH) (rectal temperature 43.5 °C).

Materials and methods. The expression of Bad and Bcl-2 was determined immunohistochemically using an indirect two-stage streptavidin-biotin method.

Results. On day 3 after EH, the expression areas of both Bad and Bcl-2 increased 2-fold, but the ratio of Bcl-2/Bad areas did not change, indicating that the intensity of apoptosis along the mitochondrial pathway in luteocytes in the acute period was  maintained within physiological values. On day  7, the Bad and Bcl-2 expression areas remained at the level of day 3, but the Bcl-2/Bad index decreased, indicating the activation of the apoptosis internal pathway in the ovarian corpus luteum cells. By day 14, the protein expression areas decreased (Bad – by 1.7 times, Bcl-2 – by 3.2 times) compared to the acute period, and the Bcl-2/Bad index decreased by 2 times compared to the control and the acute period group.

Conclusion. The observed predominance of proapoptotic Bad protein over antiapoptotic Bcl-2 in luteocytes on day 14 after EH indicates the anti-apoptotic protection violation, which leads to the apoptosis mitochondrial pathway activation of  the latter. A decrease in Bcl-2 expression can be regarded as a manifestation of the defective luteocytes removal mechanism and the body’s desire to normalize the ovarian-uterine cycle disrupted by high temperature exposure. 

Investigation of Metabolome Underlying the Biological Mechanisms of Acute Heat Stressed Granulosa Cells

Heat stress affects granulosa cells and the ovarian follicular microenvironment, ultimately resulting in poor oocyte developmental competence. This study aims to investigate the metabo-lomics response of bovine granulosa cells (bGCs) to in vitro acute heat stress of 43 °C. Heat stress triggers oxidative stress-mediated apoptosis in cultured bGCs. Heat-stressed bGCs exhibited a time-dependent recovery of proliferation potential by 48 h. A total of 119 metabolites were identified through LC-MS/MS-based metabolomics of the spent culture media, out of which, 37 metabolites were determined as differentially involved in metabolic pathways related to bioenergetics support mechanisms and the physical adaptations of bGCs. Multiple analyses of metabolome data identified choline, citric acid, 3-hydroxy-3-methylglutaric acid, glutamine, and glycocyamine as being upregulated, while galactosamine, AICAR, ciliatine, 16-hydroxyhexadecanoic acid, lysine, succinic acid, uridine, xanthine, and uraconic acid were the important downregulated metabolites in acute heat stress. These differential metabolites were implicated in various important metabolic pathways directed towards bioenergetics support mechanisms including glycerophospholipid metabolism, the citrate cycle (TCA cycle), glyoxylate and dicarboxylate metabolism, and serine, threonine, and tyrosine metabolism. Our study presents important metabolites and metabolic pathways involved in the adaptation of bGCs to acute heat stress in vitro.

A Combination of Synthetic Molecules Acts as Antifreeze for the Protection of Skin against Cold-Induced Injuries

Seasonal and occupational exposure of the human body to extreme cold temperatures can result in cell death in the exposed area due to the formation of ice crystals. This leads to superficial or deep burn injury and compromised functionality. Currently available therapeutics can be ineffective in extreme cases, and thus, it is necessary to develop prophylactic strategies. In this study, we have devised a combination of known synthetic cryopreservative agents (termed SynAFP) and evaluated their potential antifreeze applications on skin. The prophylactic activity of SynAFP in vitro is indicated by improved cellular revival and cell viability, retention of the cytoskeleton, and normal cell cycle progression even after cold stress. A comprehensive whole-cell proteomic approach revealed that in the presence of SynAFP, cold-induced downregulation of proteins involved in cell-cell adhesion and upregulation of those related to mitochondrial stress were ameliorated. Pre-application of SynAFP in mice facing a frostbite challenge prevents their skin from incurring significant injury as confirmed through macroscopic and histological examination. Moreover, multiple applications of SynAFP on mouse skin at room temperature did not compromise skin integrity. SynAFP was also formulated in anAloe vera-based cream (referred to as fSynAFP), which offered similar protection under cold stress conditions. Thus, SynAFP can be considered as a potential candidate for formulating a topical intervention for protection from cold-induced injuries to skin.

SOD1 Gene Silencing Promotes Apoptosis and Suppresses Proliferation of Heat-Stressed Bovine Granulosa Cells via Induction of Oxidative Stress

Heat stress (HS) compromises dairy cattle reproduction by altering the follicular dynamics, oocyte maturation, and normal physiological function of ovarian granulosa cells (GCs), eventually resulting in oxidative damage and cell apoptosis. To protect the cells from oxidative damage, the Superoxide dismutase-1 (SOD1) degraded the hydrogen peroxide (H₂O₂) to oxygen (O₂) and water. The objective of the current study was to investigate the impact of SOD1 silencing on intracellular ROS accumulation, cell viability, MMP, hormone synthesis (P4, E2), cell proliferation, and apoptosis in GCs under HS. The mechanistic role of SOD1 regulation in the heat-stressed GCs was explored. SOD1 gene was successfully silenced in GCs and confirmed at both transcriptional and translational levels. We found that silencing of SOD1 using siRNA under HS aggravated intracellular accumulation of reactive oxygen species, apoptosis, disrupted the mitochondrial membrane potential (MMP), altered transition of the cell cycle, and impaired synthesis of progesterone (P4) and estrogen (E2) in GCs. The associative apoptotic, steroidogenic, and cell cycle genes (BAX, Caspase-3, STAR, Cyp11A1, HSP70, PCNA, and CyclinB1) were used to confirm the results. These results identify a novel role of SOD1 in the modulation of bovine ovarian GC apoptosis, which provides a target for improving the fertility of heat-stressed dairy cows in summer.

The Antagonistic Effect of Glutamine on Zearalenone-Induced Apoptosis via PI3K/Akt Signaling Pathway in IPEC-J2 Cells

Zearalenone (ZEN) is a non-steroidal estrogen mycotoxin produced by Fusarium fungi, which inevitably exists in human and animal food or feed. Previous studies indicated that apoptosis seems to be a key determinant of ZEN-induced toxicity. This experiment aimed to investigate the protective effects of Glutamine (Gln) on ZEN-induced cytotoxicity in IPEC-J2 cells. The experimental results showed that Gln was able to alleviate the decline of cell viability and reduce the production of reactive oxygen species and calcium (Ca²⁺) induced by ZEN. Meanwhile, the mRNA expression of antioxidant enzymes such as glutathione reductase, glutathione peroxidase, and catalase was up-regulated after Gln addition. Subsequently, Gln supplementation resulted in the nuclear fission and Bad-fluorescence distribution of apoptotic cells were weakened, and the mRNA expression and protein expression of pro-apoptotic genes and apoptotic rates were significantly reduced. Moreover, ZEN reduced the phosphorylation Akt, decreased the expression of Bcl-2, and increased the expression of Bax. Gln alleviated the above changes induced by ZEN and the antagonistic effects of Gln were disturbed by PI3K inhibitor (LY294002). To conclude, this study revealed that Gln exhibited significant protective effects on ZEN-induced apoptosis, and this effect may be attributed to the PI3K/Akt signaling pathway.

Phototoxicity induced in living HeLa cells by focused femtosecond laser pulses: a data-driven approach

Nonlinear optical microscopy is a powerful label-free imaging technology, providing biochemical and structural information in living cells and tissues. A possible drawback is photodamage induced by high-power ultrashort laser pulses. Here we present an experimental study on thousands of HeLa cells, to characterize the damage induced by focused femtosecond near-infrared laser pulses as a function of laser power, scanning speed and exposure time, in both wide-field and point-scanning illumination configurations. Our data-driven approach offers an interpretation of the underlying damage mechanisms and provides a predictive model that estimates its probability and extension and a safety limit for the working conditions in nonlinear optical microscopy. In particular, we demonstrate that cells can withstand high temperatures for a short amount of time, while they die if exposed for longer times to mild temperatures. It is thus better to illuminate the samples with high irradiances: thanks to the nonlinear imaging mechanism, much stronger signals will be generated, enabling fast imaging and thus avoiding sample photodamage.

[Extranuclear p53 suppresses autophagy through AMPK/mTOR signaling to promote heat stress-induced vascular endothelial cell damage]

OBJECTIVE

To explore the role of extranuclear p53-mediated autophagy suppression by regulating AMPK/mTOR signaling pathway in heat stress (HS)-induced injury of mouse aortic endothelial cells (MAECs).

METHODS

Primary cultures of MAECs were pretreated with compound C (an AMPK inhibitor), rapamycin (a mTOR inhibitor) or pifithrin-α (PFT, a selective p53 inhibitor) for 1 h before exposure to HS (43 ℃) for 2 h. The changes in cell viability at different time points after HS were examined using CCK-8 assay, and the protein expressions of P53, LC3-II, Beclin-1, p62 and the AMPK/mTOR signaling proteins were detected using Western blotting. In the animal experiment, C57 mice were pretreated with compound C, rapamycin or PFT and exposed to a high temperature at 40 ℃ to induce HS. The pathological changes in the aorta of the mice were observed with HE staining, and cell apoptosis was detected using TUNEL staining.

RESULTS

In cultured MAECs, the cell viability was significantly reduced (P < 0.05) and the mitochondrial fraction of p53 increased while its cytoplasmic fraction decreased progressively over time following HS. HS significantly lowered the expressions of LC3-II and Beclin-1, increased p62 level, suppressed AMPK phosphorylation, and increased mTOR phosphorylation and the expressions of its downstream proteins at 6 h after the exposure (P < 0.05). Pretreatment with compound C significantly inhibited LC3-II and Beclin- 1 expression, enhanced p62 expression, and aggravated HS-induced cell injury and apoptosis in MAECs; rapamycin treatment produced the opposite effects (P < 0.05). PFT treatment significantly enhanced the viability of MAECs and alleviated HSinduced injury and apoptosis; PFT also significantly promoted activation of AMPK phosphorylation, inhibited mTOR phosphorylation and its downstream proteins (P < 0.05), enhanced the expressions of LC3-II and Beclin 1, and inhibited p62 expression in the MAECs (P < 0.05). In C57 mice, HS resulted in swelling, shedding and apoptosis of aortic vascular endothelial cells. Pretreatment with compound C obviously aggravated HS-induced vascular injury and endothelial cell apoptosis, while pretreatment with either rapamycin or PFT significantly alleviated these injuries.

CONCLUSION

Autophagy inhibition mediated by extranuclear p53 via inhibiting AMPK activity and activating mTOR signaling participates in HS-induced injury of MAECs.

Comparative transcriptome profiling of heat stress response of the mangrove crab Scylla serrata across sites of varying climate profiles

Background

The fishery and aquaculture of the widely distributed mangrove crab Scylla serrata is a steadily growing, high-value, global industry. Climate change poses a risk to this industry as temperature elevations are expected to threaten the mangrove crab habitat and the supply of mangrove crab juveniles from the wild. It is therefore important to understand the genomic and molecular basis of how mangrove crab populations from sites with different climate profiles respond to heat stress. Towards this, we performed RNA-seq on the gill tissue of S. serrata individuals sampled from 3 sites (Cagayan, Bicol, and Bataan) in the Philippines, under normal and heat-stressed conditions. To compare the transcriptome expression profiles, we designed a 2-factor generalized linear model containing interaction terms, which allowed us to simultaneously analyze within-site response to heat-stress and across-site differences in the response.

Results

We present the first ever transcriptome assembly of S. serrata obtained from a data set containing 66 Gbases of cleaned RNA-seq reads. With lowly-expressed and short contigs excluded, the assembly contains roughly 17,000 genes with an N50 length of 2,366 bp. Our assembly contains many almost full-length transcripts – 5229 shrimp and 3049 fruit fly proteins have alignments that cover >80% of their sequence lengths to a contig. Differential expression analysis found population-specific differences in heat-stress response. Within-site analysis of heat-stress response showed 177, 755, and 221 differentially expressed (DE) genes in the Cagayan, Bataan, and Bicol group, respectively. Across-site analysis showed that between Cagayan and Bataan, there were 389 genes associated with 48 signaling and stress-response pathways, for which there was an effect of site in the response to heat; and between Cagayan and Bicol, there were 101 such genes affecting 8 pathways.

Conclusion

In light of previous work on climate profiling and on population genetics of marine species in the Philippines, our findings suggest that the variation in thermal response among populations might be derived from acclimatory plasticity due to pre-exposure to extreme temperature variations or from population structure shaped by connectivity which leads to adaptive genetic differences among populations.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12864-021-07891-w).

Burn Injury: Mechanisms of Keratinocyte Cell Death

Cutaneous burn injury is associated with epidermal loss in the zone of coagulation zone and delayed tissue loss in the zone of stasis. Thus, thermal stress can trigger both necrosis and regulated cell death (RCD) or apoptosis. Experimental in vitro and in vivo work has clearly demonstrated apoptotic events of thermally injured keratinocytes that are accompanied by morphological and biochemical markers of regulated cell death. However, in vivo data for the different pathways of regulated cell death are sparse. In vitro experiments with heat-stressed human keratinocytes have demonstrated death receptor involvement (extrinsic apoptosis), calcium influx, and disruption of mitochondrial membrane potential (intrinsic apoptosis) in regulated cell death. In addition, caspase-independent pathways have been suggested in regulated cell death. Keratinocyte heat stress leads to reduced proliferation, possibly as a result of reduced keratinocyte adhesion (anoikis) or oncogene involvement. Understanding the underlying mechanisms of RCD and the skin’s responses to thermal stress may lead to improved strategies for treating cutaneous burn trauma.

Effect of Melatonin on Expression of Apoptosis Regulator Proteins Bcl-2 and Bad in Ovarian Follicular Apparatus after High Temperature Exposure

Expression of proapoptotic Bad and antiapoptotic Bcl-2 proteins in ovarian follicular apparatus of Wistar rats was evaluated on days 3, 7, and 14 after single experimental hyperthermia (EH) followed by therapeutic correction with subcutaneous melatonin (0.1 mg) dissolved in 0.2 ml physiological saline (PS) injected daily for 3 days. Duration of EH was less than 17 min; it was terminated when the rectal temperature attained 43.5°C. In acute posthyperthermia period (on experimental day 3), Bcl-2 and Bad expression area in folliculocytes of the experimental (EH+melatonin) and reference rats simultaneously increased in comparison with the corresponding values in control rats. At this, Bcl-2/Bad ratio of expression areas in experimental and reference rats did not differ from the control level. During the recovery period (on posthyperthermia day 7), Bad protein expression area significantly decreased in experimental rats resulting in elevation of Bcl-2/Bad ratio in comparison with control and reference groups on days 3 and 7. On day 14, Bcl-2 and Bad expression areas and Bcl-2/Bad ratio restored in experimental animals to the corresponding values assessed in control and reference groups. Thus, melatonin produced no effect on Bcl-2/Bad protein expression ratio during acute posthyperthermia period, but reduced the expression area of proapoptotic Bad protein and increased Bcl-2/Bad ratio on posthyperthermia day 7. Thus, melatonin can inhibit apoptosis via mitochondrial pathway in ovarian follicles on posthyperthermia day 7.

Modulation of Heat-Shock Proteins Mediates Chicken Cell Survival against Thermal Stress

Heat stress is one of the most challenging environmental stresses affecting domestic animal production, particularly commercial poultry, subsequently causing severe yearly economic losses. Heat stress, a major source of oxidative stress, stimulates mitochondrial oxidative stress and cell dysfunction, leading to cell damage and apoptosis. Cell survival under stress conditions needs urgent response mechanisms and the consequent effective reinitiation of cell functions following stress mitigation. Exposure of cells to heat-stress conditions induces molecules that are ready for mediating cell death and survival signals, and for supporting the cell's tolerance and/or recovery from damage. Heat-shock proteins (HSPs) confer cell protection against heat stress via different mechanisms, including developing thermotolerance, modulating apoptotic and antiapoptotic signaling pathways, and regulating cellular redox conditions. These functions mainly depend on the capacity of HSPs to work as molecular chaperones and to inhibit the aggregation of non-native and misfolded proteins. This review sheds light on the key factors in heat-shock responses for protection against cell damage induced by heat stress in chicken.

Cardioprotective effect of Rosa canina L. methanolic extract on heat shock induced cardiomyocyte injury: An experimental study

Introduction: Overexposure to heat conditions can affect the functioning of the cardiovascular system and may promote cardiovascular disorders. Heat shock induced myocardial injury via increasing endoplasmic reticulum response-mediated apoptosis. This study investigated the impact of pretreatment with Rosa canina (RC), a natural antioxidant, on myocardial damage induced by heat stress exposure and underlying mechanisms in cardiomyocytes in rats. Methods: Sixty adult male Wistar rats were allocated into five groups, including Control: received normal saline (NS), Heat Stress (HS), and HS+RC groups. Animals in the HS groups were subjected to heat stress (43 ºC) for 15 minutes once a day for two weeks. Animals in the HS+RC groups received three doses of RC (250, 500, and 1000 mg/mL) one hour before being subjected to heat shock. The endoplasmic reticulum (ER) transmembrane kinases, including PKR-like endoplasmic reticulum kinase (PERK), immunoreactivity of CCAAT/enhancer-binding protein homologous protein (CHOP), and eukaryotic translation initiation factor 2-alpha (eIF2α) as well as caspase 8 were detected by Western blot. The levels of reactive oxygen species (ROS) were assessed. Moreover, histopathological changes and apoptosis were also assayed in the heart tissue by using histopathological and TUNEL assays. Results: Heat exposure increased the level of ROS and induced oxidative damage in the heart tissue. The results demonstrated that RC administration decreased the overproduction of ROS induced by heat stress in cardiomyocytes. Moreover, heat stress up regulated the expression of p-PERK, p-eIF2α,and CHOP protein while pretreatment with RC decreased expression of ER stress-related markers in cardiomyocytes. Besides, RC diminished heat stress-induced cellular damage and apoptosis associated with inhibition of caspase 8 activation, a pro-apoptotic protein in cardiomyocytes. Conclusion: These findings indicate that RC exerts a protective effect on heart tissue, at least in part,through inactivation of PERK/eIF2α/CHOP pathway or inhibition of ER stress and oxidative stress triggeredapoptosis in cardiomyocytes induced by heat stress.

Targeted temperature management in patients with severe heatstroke: Three case reports and treatment recommendations

RATIONALE

Unprecedented heatwaves over the past several years are getting worse with longer duration in the course of global warming. Heatstroke is a medical emergency with multiple organ involvement and life-threatening illness with a high mortality rate of up to 71%. Uncontrolled damage to the central nervous system can result in severe cerebral edema, permanent neurological sequelae, and death. However, regarding the therapeutic aspects of heat stroke, there was no therapeutic strategy after the rapid cooling of the core body temperature to <39°C to prevent further injury.

PATIENT CONCERNS

Each of 3 patients developed a change of mental statuses after the exposure to summer heatwaves or relatively high environmental temperatures with high humidity in the sauna.

DIAGNOSES

The patients were diagnosed with severe heatstroke since they showed cerebral edema and multiple organ dysfunction based on the results from laboratory tests and the findings in brain computed tomography scan.

INTERVENTIONS

The patients underwent induced therapeutic hypothermia (<36°C) between 24 and 36 hours in the management of severe heatstroke.

OUTCOMES

The patients survived from cerebral edema and multiple organ dysfunction.

LESSONS

We believe that targeted temperature management (<36°C) will help treat severe heatstroke. Thus it should be considered for reducing the chance of development of complications in multiple organs, especially in the central nervous system, when managing patients with severe heatstroke.

Cellular and functional adaptation to thermal stress in ovarian granulosa cells in mammals

Climate change represents a significant environmental challenge to human welfare. One of many negative impacts may be on animal reproduction. Elevated ambient temperature unfavourably influences reproductive processes in mammals. High temperature can affect reproductive processes such as follicle development and may alter follicular fluid concentrations of amino acids, fatty acids, minerals, enzymes, antioxidants defence and growth factors. These impacts may lead to inferior oocyte competence and abnormal granulosa cell (GCs) function. Mammalian oocytes are enclosed by GCs that secret hormones and signalling molecules to promote oocyte competence. GCs are essential for proper follicular development, oocyte maturation, ovulation, and luteinization. Many environmental stressors, including thermal stress, affect GC function and alter oocyte development and growth. Several studies documented a link between elevated ambient temperature and increased generation of cellular reactive oxygen species (ROS). ROS can damage DNA, reduce cell proliferation, and induce apoptosis in GCs, thus altering oocyte development. Additionally, thermal stress induces upregulation of thermal shock proteins, such as HSP70 and HSP90. This review provides an update on the influence of thermal stress on GCs of mammals. Discussions include impacts to steroidogenesis (estradiol and progesterone), proliferation and cell cycle transition, apoptosis, oxidative stress (ROS), antioxidants related genes, heat shock proteins (HSPs) and endoplasmic reticulum responses.

RNAi-Mediated Silencing of Catalase Gene Promotes Apoptosis and Impairs Proliferation of Bovine Granulosa Cells under Heat Stress

Heat stress in dairy cattle is recognized to compromise fertility by altering the functions of ovarian follicle-enclosed cells, e.g., oocyte and granulosa cells (GCs). Catalase is an antioxidant enzyme that plays a significant role in cellular protection against oxidative damage by the degradation of hydrogen peroxide to oxygen and water. In this study, the role and mechanism of CAT on the heat stress (HS)-induced apoptosis and altered proliferation of bovine GCs were studied. The catalase gene was knocked-down successfully in bovine GCs at both the transcriptional and translational levels. After a successful knockdown using siRNA, GCs were divided into HS (40 °C + NC and 40 °C + CAT siRNA) and 38 °C + NC (NC) groups. The GCs were then examined for ROS, viability, mitochondrial membrane potential (MMP), cell cycle, and biosynthesis of progesterone (P4) and estrogen (E2) hormones. The results indicated that CAT silencing promoted ROS production and apoptosis by up-regulating the Bcl-2-associated X protein (BAX) and Caspase-3 genes both at the transcriptional and translational levels. Furthermore, the knockdown of CAT markedly disrupted the MMP, impaired the production of P4 and E2, altered the progression of the G1 phase of the cell cycle, and decreased the number of cells in the S phase. This was further verified by the down-regulation of proliferating cell nuclear antigen (PCNA), CyclinB1, steroidogenic acute regulatory protein (STAR), and cytochrome P450 family 11 subfamily A member 1 (Cyp11A1) genes. Our study presented a novel strategy to characterize how CAT can regulate cell proliferation and apoptosis in GCs under HS. We concluded that CAT is a broad regulatory marker in GCs by regulating apoptosis, cellular progression, and simultaneously by vital fluctuations in hormonal signaling. Our findings infer a crucial evidence of how to boost the fertility of heat-stressed cows.

DNA fragmentation of human spermatozoa: Simple assessment of single- and double-strand DNA breaks and their respective dynamic behavioral response

BACKGROUND

Procedures to detect sperm DNA fragmentation (SDF), like the sperm chromatin dispersion (SCD) test, determine the "global" SDF without discriminating between spermatozoa with single-strand DNA breaks only (SDF-SSBs) and those containing double-strand DNA breaks (SDF-DSBs).

OBJECTIVES

(a) To validate a test to distinguish human spermatozoa with massive DSBs (DSB-SCD assay), (b) to study the baseline SDF-SSBs and SDF-DSBs, and (c) to assess their dynamics in vitro.

MATERIALS AND METHODS

(a) SDF-DSBs were determined by visualization of diffused DNA fragments from spermatozoa lysed under non-denaturing conditions. This was validated by in vitro incubation with DNase I and the comet assay. (b) Baseline SDF-DSBs and SDF-SSBs were determined in ejaculates from 95 males. (c) Their dynamic appearance was studied in samples untreated or exposed to hyperthermia, acidic pH, nitric oxide released by sodium nitroprusside (SNP), and the metabolic energy inhibitors 2-deoxy-D-glucose and antimycin A.

RESULTS

(a) DNase I and comet assay experiments confirmed that the assay successfully determined SDF-DSBs. (b) The higher the SDF of the semen sample, the higher the frequency of SSBs, whereas DSBs behaved independently. Abnormal samples showed higher SDF than normozoospermic, the difference being only significant for SDF-SSBs. (c) During the first hours of incubation, the linear rate of increase in SDF-SSBs was 3.7 X higher than that of SDF-DSBs. All hazardous agents accelerated the SDF rate when compared to untreated spermatozoa, primarily being associated with SDF-SSBs. SNP treatment was the most damaging, rapidly inducing spermatozoa with SSBs which progressively evolved to DSBs. Remarkably, this phenomenon was also evidenced after acute SNP exposure, revealing cryptic sperm damage.

CONCLUSION

The DSBs-SCD is an easy complement for SDF assessment. The dynamic study of SSBs and DSBs may improve the evaluation of sperm quality in clinical settings, particularly "unmasking" the presence of non-specific cryptic sperm damage that might otherwise go undetected.

Molecular cloning, characterization and expression analysis of p53 from turbot Scophthalmus maximus and its response to thermal stress

The tumor suppressor protein, p53 plays a crucial role in protecting genetic integrity. Once activated by diverse cell stresses, p53 reversibly activates downstream target genes to regulate cell cycle and apoptosis. However, few studies have investigated the effects of thermal stress in turbot, specifically the p53 signaling pathway. In this study, the rapid amplification of cDNA ends was used to obtain a full-length cDNA of the turbot p53 gene (Sm-p53) and perform bioinformatics analysis. The results showed that the cDNA of the Sm-p53 gene was 2928 bp in length, encoded a 381 amino acid protein, with a theoretical isoelectric point of 6.73. It was composed of a DNA binding and a tetramerization domain. Expression of Sm-p53 in different tissues was detected and quantified by qRT-PCR, and was highest in the liver. We also investigated the expression profiles of Sm-p53 in different tissue and TK cells after thermal stress. These result suggested that Sm-p53 plays a key role, and provides a theoretical basis for Sm-p53 changes in environmental stress responses in the turbot.

A Novel Peptide Oligomer of Bacitracin Induces M1 Macrophage Polarization by Facilitating Ca2+ Influx

Antimicrobial peptides (AMPs) are components of the innate immune system and form the first defense against pathogens for various organisms. In the present study, we assessed whether CSP32, a novel AMP oligomer of bacitracin isolated from a strain of Bacillus spp., regulates the polarization of murine macrophage-like RAW 264.7 cells. CSP32 stimulated phagocytosis while inducing the appearance of the typical M1 polarized macrophage phenotype; these M1 macrophages play a role in host defense against pathogens. Furthermore, our results showed that CSP32 enhanced the expression and production of pro-inflammatory mediators, such as cytokines and chemokines. In addition, the CSP32-stimulated inflammatory mediators were induced mainly by the mitogen-activated protein kinase/nuclear factor kappa B (MAPK/NF-κB) signaling pathway during M1 macrophage polarization. In particular, CSP32 markedly increased the numbers of Ca²⁺-positive macrophages while upregulating phospholipase C and activating protein kinase Cε. Furthermore, the inhibition of intracellular Ca²⁺ by BAPTA-AM, a Ca²⁺ chelator, significantly suppressed the CSP32-mediated phagocytosis, inflammatory mediator production, and NF-κB activation. In conclusion, our data suggested that CSP32-stimulated M1 macrophage polarization is dependent on the calcium signaling pathway and may result in enhanced immune capacities.

Changing faces of stress: Impact of heat and arsenite treatment on the composition of stress granules

Stress granules (SGs), hallmarks of the cellular adaptation to stress, promote survival, conserve cellular energy, and are fully dissolved upon the cessation of stress treatment. Different stresses can initiate the assembly of SGs, but arsenite and heat are the best studied of these stresses. The composition of SGs and posttranslational modifications of SG proteins differ depending on the type and severity of the stress insult, methodology used, cell line, and presence of overexpressed and tagged proteins. A group of 18 proteins showing differential localization to SGs in heat- and arsenite-stressed mammalian cell lines is described. Upon severe and prolonged stress, physiological SGs transform into more solid protein aggregates that are no longer reversible and do not contain mRNA. Similar pathological inclusions are hallmarks of neurodegenerative diseases. SGs induced by heat stress are less dynamic than SGs induced by arsenite and contain a set of unique proteins and linkage-specific polyubiquitinated proteins. The same types of ubiquitin linkages have been found to contribute to the development of neurodegenerative disorders such as Parkinson disease, Alzheimer disease, and amyotrophic lateral sclerosis (ALS). We propose heat stress-induced SGs as a possible model of an intermediate stage along the transition from dynamic, fully reversible arsenite stress-induced SGs toward aberrant SGs, the hallmark of neurodegenerative diseases. Stress- and methodology-specific differences in the compositions of SGs and the transition of SGs to aberrant protein aggregates are discussed. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Export and Localization > RNA Localization.