PM2.5 induces mitochondrial dysfunction via AHR-mediated cyp1a1 overexpression during zebrafish heart development

Mitigating PM2.5 Induced Myocardial Metal Deposition Through Sodium Thiosulfate Resulted in Reduction of Cardiotoxicity and Physiological Recovery From Ischemia-Reperfusion via Mitochondrial Preservation

The cardiovascular risks linked to PM2.5 include calcification in both vasculature and myocardial tissues, leading to structural changes and functional decline. Through the selection of a clinically proven endogenous agent, sodium thiosulfate (STS), capable of addressing PM2.5 related cardiac abnormalities, we not only address the absence of effective solutions to mitigate PM2.5 toxicity, but also provide evidence for the repurposing potential of STS in ameliorating PM2.5 induced cardiac damage. Female Wistar rats were exposed to PM2.5 (250 μg/m3) for 3 h daily for 21 days. STS was administered thrice weekly for 3 weeks during exposure after which the hearts were excised and mounted on a Langendorff apparatus for induction of ischemia-reperfusion injury (IR). STS administration improved cardiac function in PM2.5 exposed rat hearts, accompanied by increased expression of the master regulator gene PGC1-α and increased mitochondrial mass. Moreover, STS restored bioenergetic function and balanced mitochondrial fission-fusion dynamics. The beneficial effects of STS were further evidenced by its ability to scavenge metals, thereby reducing heavy metal deposition in mitochondria and alleviating oxidative stress and inflammation. Furthermore, STS facilitated the clearance of damaged mitochondria through mitophagy. Additionally, STS activated the PI3K/AKT/GSK3ß signaling pathway, providing cardio protection against IR injury in PM2.5-exposed hearts by preserving mitochondrial function. These results underscore the potential therapeutic benefits of STS in mitigating the adverse cardiac effects induced by PM2.5 exposure. The translation of these findings to clinical practice holds promise for the development of targeted interventions aimed at reducing the cardiovascular toxicity associated with PM2.5 exposure.

The resveratrol attenuates reactive oxygen species mediated DNA damage in cardiac malformations caused by 4-tert-octylphenol

4-tert-octylphenol (4-t-OP) is an alkylphenolic environmental endocrine disruptor extensively distributed in the environment, posing potential hazards to living organisms. Research has demonstrated that 4-t-OP induces cardiac injury and abnormalities in embryonic development, which can adversely affect heart development. The excessive production of reactive oxygen species (ROS) triggered by 4-t-OP may result in DNA damage. Hence, we hypothesized that ROS-mediated DNA damage plays a crucial role in abnormal cardiac development in zebrafish embryos exposed to 4-t-OP, while resveratrol (RSV), a common antioxidant found in natural foods, may provide protection. In this study, we exposed zebrafish embryos at 2 h post-fertilization (hpf) to various doses of 4-t-OP in combination with relevant inhibitor/agonist therapies. Using microscopy, we observed morphological alterations in the cardiac structure of zebrafish embryos at 72 hpf. The underlying molecular mechanisms were assessed through immunofluorescence, DCFH-DA probe, MitoSOX™ staining, Quantitative polymerase chain reaction, and other methods. Our findings revealed that 4-t-OP caused dose-dependent cardiac defects in zebrafish embryos. The overexpression of ROS/mitochondrial ROS (mtROS) induced by 4-t-OP was significantly reduced by the addition of RSV or the ROS inhibitor N-acetyl-L-cysteine (NAC). Furthermore, the inclusion of RSV or NAC significantly mitigated cardiac deformities, cardiac apoptosis, and DNA damage. Additionally, the apoptosis inhibitor Ac-DEVD-CHO and the Wnt/β-catenin agonist CHIR99021 decreased 4-t-OP-induced cardiac abnormalities. Moreover, the naturally occurring small molecule chemical RSV provided protection against 4-t-OP-induced heart developmental injury. This study elucidates the molecular mechanisms by which 4-t-OP induces oxidative stress, DNA damage, and cardiac defects in the heart of zebrafish larvae through the ROS/Wnt/β-catenin signaling pathway. These findings present novel molecular targets for the prevention and therapy of congenital heart disease, as well as enhance our understanding of the cardiotoxic effects of 4-t-OP.

Extractable organic matter from PM2.5 inhibits cardiomyocyte differentiation via AHR-mediated m6A RNA methylation

An ever-increasing body of research has established a link between maternal PM2.5 exposure and congenital heart diseases in the offspring, but the underlying mechanisms remain elusive. We recently reported that activation of the aryl hydrocarbon receptor (AHR) by PM2.5 causes aberrant m6A RNA methylation, leading to cardiac malformations in zebrafish embryos. We hypothesized that PM2.5 can disrupt heart development by inducing m6A methylation changes through AHR in mammals. In this study, we observed that extractable organic matters (EOM) from PM2.5 significantly impaired cardiomyocyte differentiation in embryonic rat cardiomyoblasts H9c2. Importantly, EOM exposure reduced global m6A methylation levels, which was reversed by AHR inhibition. Moreover, AHR, activated by EOM directly promoted the transcription of the demethylase, FTO, leading to global m6A hypomethylation. Specifically, AHR-induced FTO overexpression decreased the m6A methylation levels of Nox4 mRNA, resulting in NOX4 overexpression and subsequent oxidative stress in EOM samples. We then demonstrated that oxidative stress contributes to the inhibition of cardiomyocyte differentiation by EOM through suppression of Wnt/β-catenin signaling. In summary, our findings indicate that AHR activation by PM2.5 directly enhances the expression of the demethylase, FTO, which increases NOX4 expression by reducing its m6A methylation. The oxidative stress caused by NOX4 overexpression inhibits Wnt/β-catenin signaling, thereby compromising cardiomyocyte differentiation.

Fine particulate matter‑induced cardiac developmental toxicity (Review)

Fine particulate matter (PM2.5) has become an important risk factor threatening human health. Epidemiological and toxicological investigations have revealed that PM2.5 not only leads to cardiovascular dysfunction, but it also gives rise to various adverse health effects on the human body, such as cardiovascular and cerebrovascular diseases, cancers, neurodevelopmental disorders, depression and autism. PM2.5 is able to penetrate both respiratory and placental barriers, thereby resulting in negative effects on fetal development. A large body of epidemiological evidences has suggested that gestational exposure to PM2.5 increases the incidence of congenital diseases in offspring, including congenital heart defects. In addition, animal model studies have revealed that gestational exposure to PM2.5 can disrupt normal heart development in offspring, although the potential molecular mechanisms have yet to be fully elucidated. The aim of the present review was to provide a brief overview of what is currently known regarding the molecular mechanisms underlying cardiac developmental toxicity in offspring induced by gestational exposure to PM2.5.

Constructing an adverse outcome pathway framework for the impact of maternal exposure to PM2.5 on liver development and injury in offspring

Ambient fine particulate matter (PM2.5) is a significant contributor to air pollution. PM2.5 exposure poses a substantial hazard to public health. In recent years, the adverse effects of maternal PM2.5 exposure on fetal health have gradually gained public attention. As the largest organ in the body, the liver has many metabolic and secretory functions. Liver development, as well as factors that interfere with its growth and function, are of concern. This review utilized the adverse outcome pathway (AOP) framework as the analytical approach to demonstrate the link between maternal PM2.5 exposure and potential neonatal liver injury from the molecular to the population level. The excessive generation of reactive oxygen species (ROS), subsequent endoplasmic reticulum (ER) stress, and oxidative stress were regarded as the essential components in this framework, as they could trigger adverse developmental outcomes in the offspring through DNA damage, autophagy dysfunction, mitochondrial injury, and other pathways. To the best of our knowledge, this is the first article based on an AOP framework that elaborates on the influence of maternal exposure to PM2.5 on liver injury occurrence and adverse effects on liver development in offspring. Therefore, this review offered mechanistic insights into the developmental toxicity of PM2.5 in the liver, which provided a valuable basis for future studies and prevention strategies.

Mitochondrial dysfunction induced by ambient fine particulate matter and potential mechanisms

Air pollution is one of the major environmental threats contributing to the global burden of disease. Among diverse air pollutants, fine particulate matter (PM2.5) poses a significant adverse health impact and causes multi-system damage. As a highly dynamic organelle, mitochondria are essential for cellular energy metabolism and vital for cellular homeostasis and body fitness. Moreover, mitochondria are vulnerable to external insults and common targets for PM2.5-induced cellular damage. The resultant impairment of mitochondrial structure and function initiates the pathogenesis of diverse human diseases. This review mainly summarizes the in vivo and in vitro findings of PM2.5-induced mitochondrial dysfunction and its implication in PM2.5-induced health effects. Furthermore, recent advances toward the underlying mechanisms of PM2.5 and its components-induced mitochondrial dysfunction are also discussed, with an attempt to provide insights into the toxicity of PM2.5 and basic information for devising appropriate intervention strategies.

Metformin attenuates PM2.5-induced oxidative stress by inhibiting the AhR/CYP1A1 pathway in proximal renal tubular epithelial cells

The harmful effects of PM2.5 on human health, including an increased risk of chronic kidney disease (CKD), have raised a lot of attention, but the underlying mechanisms are unclear. We used the Shanghai Meteorological and Environmental Animal Exposure System (Shanghai-METAS) to simulate the inhalation of PM2.5 in the real environment and established an animal model by exposing C57BL/6 mice to filtered air (FA) and Particulate Matter (PM2.5) for 8 weeks. PM2.5 impaired the renal function of the mice, and the renal tubules underwent destructive changes. Analysis of NHANES data showed a correlation between reduced kidney function and higher blood levels of PM2.5 components, polychlorinated biphenyls (PCBs) and dioxins, which are Aryl hydrocarbon Receptor (AhR) ligands. PM2.5 exposure induced higher levels of AhR and CYP1A1 and oxidative stress as evidenced by the higher levels of ROS, MDA, and GSSG in kidneys of mice. PM2.5 exposure led to AhR overexpression and nuclear translocation in proximal renal tubular epithelial cells. Inhibition of AhR reduced CYP1A1 expression and PM2.5-increased levels of ROS, MDA and GSSG. Our study suggested metformin can mitigate PM2.5-induced oxidative stress by inhibiting the AhR/CYP1A1 pathway. These findings illuminated the role of AhR/CYP1A1 pathway in PM2.5-induced kidney injury and the protective effect of metformin on PM2.5-induced cellular damage, offering new insights for air pollution-related renal diseases.

Periconceptional polycyclic aromatic hydrocarbon levels in maternal hair and fetal risk for congenital heart defects

BACKGROUND

Congenital heart defects (CHDs) have a complex etiology, and environmental factors play an important role in their occurrence. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous chemicals, and some have teratogenic potential. However, few studies have examined PAHs exposure and CHD risk. We investigated the association between PAHs in maternal scalp hair and CHD risk.

METHODS

A case-control study involving 170 severe CHD cases and 170 healthy controls was conducted, and the concentrations of 11 PAHs in maternal hair grown during the periconceptional period were quantified. A generalized linear mixed model (GLMM) was used to determine the effects of each PAHs on the risk for CHDs. Weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) were used to assess the overall effects of the 11-PAHs mixture on the risk for CHDs.

RESULTS

The median concentration of chrysene (CHR) was higher in CHD cases (9.75 ng/g) than in controls (6.50 ng/g). In GLMM, higher levels of CHR were associated with a 4.88-fold greater risk for CHDs (95 % confidence interval [CI]: 2.69-8.89). In WQS regression, higher levels of PAHs mixture were associated with a 2.03-fold greater CHD risk (95 % CI: 1.75-2.31), and CHR had the highest weighting (weighted 0.9346). In BKMR, CHD risks increased steadily with the levels of the PAHs mixture. CHR showed a toxic effect when the other PAHs were fixed at their 25th, 50th, or 75th percentile. No interactions among PAHs were found.

CONCLUSIONS

When examined individually, a high concentration of CHR in periconceptional maternal hair was associated with an increased risk for CHDs. When considering the 11 PAHs together, higher levels of the PAHs mixture were associated with increased odds of CHD occurrence.

Silibinin inhibits PM2.5-induced liver triglyceride accumulation through enhancing the function of mitochondrial Complexes I and II

Background

The standardized extract of milk thistle seeds, known as silibinin, has been utilized in herbal medicine for over two centuries, with the aim of safeguarding the liver against the deleterious effects of various toxic substances. However, the role of silibinin in Particulate Matter (PM2.5)-induced intrahepatic triglyceride accumulation remains unclear. This study seeks to investigate the impact of silibinin on PM2.5-induced intrahepatic triglyceride accumulation and elucidate potential underlying mechanisms.

Methods

A model of intrahepatic triglyceride accumulation was established in male C57BL/6J mice through intratracheal instillation of PM2.5, followed by assessment of liver weight, body weight, liver index, and measurements of intrahepatic triglycerides and cholesterol after treatment with silibinin capsules. Hep G2 cells were exposed to PM2.5 suspension to create an intracellular triglyceride accumulation model, and after treatment with silibinin, cell viability, intracellular triglycerides and cholesterol, fluorescence staining for Nile Red (lipid droplets), and DCFH-DA (Reactive Oxygen Species, ROS), as well as proteomics, real-time PCR, and mitochondrial function assays, were performed to investigate the mechanisms involved in reducing triglycerides.

Results

PM2.5 exposure leads to triglyceride accumulation, increased ROS production, elevated expression of inflammatory factors, decreased expression of antioxidant factors, and increased expression of downstream genes of aryl hydrocarbon receptor. Silibinin can partially or fully reverse these factors, thereby protecting cells and animal livers from PM2.5-induced damage. In vitro studies show that silibinin exerts its protective effects by preserving oxidative phosphorylation of mitochondrial complexes I and II, particularly significantly enhancing the function of mitochondrial complex II. Succinate dehydrogenase (mitochondrial complex II) is a direct target of silibinin, but silibinin A and B exhibit different affinities for different subunits of complex II.

Conclusion

Silibinin improved the accumulation of intrahepatic triglycerides induced by PM2.5, and this was, at least in part, explained by an enhancement of oxidative phosphorylation in mitochondrial Complexes I and II.

Isomer-specific cardiotoxicity induced by tricresyl phosphate in zebrafish embryos/larvae

Tricresyl phosphate (TCP) has received extensive attentions due to its potential adverse effects, while the toxicological information of TCP isomers is limited. In this study, 2 h post-fertilization zebrafish embryos were exposed to tri-o-cresyl phosphate (ToCP), tri-m-cresyl phosphate (TmCP) or tri-p-cresyl phosphate (TpCP) at concentrations of 0, 100, 300 and 600 μg/L until 120 hpf, and the cardiotoxicity and mechanism of TCP isomers in zebrafish embryos/larvae were evaluated. The results showed that ToCP or TmCP exposure induced cardiac morphological defects and dysfunction in zebrafish, characterized by increased distance between sinus venosus and bulbus arteriosis, increased atrium and pericardial sac area, trabecular defects, and decreased heart rate and blood flow velocity, while no adverse effects of TpCP on zebrafish heart were found. Transcriptomic results revealed that extracellular matrix (ECM) and motor proteins, as well as PPAR signaling pathways, were included in the cardiac morphological defects and dysfunction induced by ToCP and TmCP. Co-exposure test with D-mannitol indicated that the inhibition of energy metabolism by ToCP and TmCP affected cardiac morphology and function by decreasing osmoregulation. This study is the first to report the cardiotoxicity induced by TCP in zebrafish from an isomer perspective, providing a new insight into the toxicity of TCP isomers and highlighting the importance of evaluating the toxicity of different isomers.

PM2.5 Induces Cardiomyoblast Senescence via AhR-Mediated Oxidative Stress

Previous research has established a correlation between PM2.5 exposure and aging-related cardiovascular diseases, primarily in blood vessels. However, the impact of PM2.5 on cardiomyocyte aging remains unclear. In this study, we observed that extractable organic matter (EOM) from PM2.5 exposure led to cellular senescence in H9c2 cardiomyoblast cells, as characterized by an increase in the percentage of β-galactosidase-positive cells, elevated expression levels of p16 and p21, and enhanced H3K9me3 foci. EOM also induced cell cycle arrest at the G1/S stage, accompanied by downregulation of CDK4 and Cyclin D1. Furthermore, EOM exposure led to a significant elevation in intracellular reactive oxygen species (ROS), mitochondrial ROS, and DNA damage. Supplementation with the antioxidant NAC effectively attenuated EOM-induced cardiac senescence. Our findings also revealed that exposure to EOM activated the aryl hydrocarbon receptor (AhR) signaling pathway, as evidenced by AhR translocation to the nucleus and upregulation of Cyp1a1 and Cyp1b1. Importantly, the AhR antagonist CH223191 effectively mitigated EOM-induced oxidative stress and cellular senescence. In conclusion, our results indicate that PM2.5-induced AhR activation leads to oxidative stress, DNA damage, and cell cycle arrest, leading to cardiac senescence. Targeting the AhR/ROS axis might be a promising therapeutic strategy for combating PM2.5-induced cardiac aging.

The mitochondria-targeted antioxidant MitoQ ameliorates inorganic arsenic-induced DCs/Th1/Th2/Th17/Treg differentiation partially by activating PINK1-mediated mitophagy in murine liver

Inorganic arsenic is a well-established environmental toxicant linked to acute liver injury, fibrosis, and cancer. While oxidative stress, pyroptosis, and ferroptosis are known contributors, the role of PTEN-induced kinase 1 (PINK1)-mediated mitophagy in arsenic-induced hepatic immunotoxicity remains underexplored. Our study revealed that acute arsenic exposure prompts differentiation of hepatic dendritic cells (DCs) and T helper (Th) 1, Th2, Th17, and regulatory T (Treg) cells, alongside increased transcription factors and cytokines. Inorganic arsenic triggered liver redox imbalance, leading to elevated alanine transaminase (ALT), hydrogen peroxide (H2O2), malondialdehyde (MDA), and activation of nuclear factor erythroid 2-related factor (Nrf2)/heme oxygenase-1 (HO-1) pathway. PINK1-mediated mitophagy was initiated, and its inhibition exacerbates H2O2 accumulation while promoting DCs/Th1/Th2/Treg differentiation in the liver of arsenic-exposed mice. Mitoquinone (MitoQ) pretreatment relieved arsenic-induced acute liver injury and immune imbalance by activating Nrf2/HO-1 and PINK1-mediated mitophagy. To our knowledge, this is the first report identifying PINK1-mediated mitophagy as a protective factor against inorganic arsenic-induced hepatic DCs/Th1/Th2 differentiation. This study has provided new insights on the immunotoxicity of inorganic arsenic and established a foundation for exploring preventive and therapeutic strategies targeting PINK1-mediated mitophagy in acute liver injury. Consequently, the application of mitochondrial antioxidant MitoQ may offer a promising treatment for the metalloid-induced acute liver injury.

Short-term exposure to fine particulate matter exposure impairs innate immune and inflammatory responses to a pathogen stimulus: A functional study in the zebrafish model

Short-term exposure to fine particulate matter (PM2.5) is associated with the activation of adverse inflammatory responses, increasing the risk of developing acute respiratory diseases, such as those caused by pathogen infections. However, the functional mechanisms underlying this evidence remain unclear. In the present study, we generated a zebrafish model of short-term exposure to a specific PM2.5, collected in the northern metropolitan area of Milan, Italy. First, we assessed the immunomodulatory effects of short-term PM2.5 exposure and observed that it elicited pro-inflammatory effects by inducing the expression of cytokines and triggering hyper-activation of both neutrophil and macrophage cell populations. Moreover, we examined the impact of a secondary infectious pro-inflammatory stimulus induced through the injection of Pseudomonas aeruginosa lipopolysaccharide (Pa-LPS) molecules after exposure to short-term PM2.5. In this model, we demonstrated that the innate immune response was less responsive to a second pro-inflammatory infectious stimulus. Indeed, larvae exhibited dampened leukocyte activation and impaired production of reactive oxygen species. The obtained results indicate that short-term PM2.5 exposure alters the immune microenvironment and affects the inflammatory processes, thus potentially weakening the resistance to pathogen infections.

Developmental Toxicity of Fine Particulate Matter: Multifaceted Exploration from Epidemiological and Laboratory Perspectives

Particulate matter of size ≤ 2.5 μm (PM2.5) is a critical environmental threat that considerably contributes to the global disease burden. However, accompanied by the rapid research progress in this field, the existing research on developmental toxicity is still constrained by limited data sources, varying quality, and insufficient in-depth mechanistic analysis. This review includes the currently available epidemiological and laboratory evidence and comprehensively characterizes the adverse effects of PM2.5 on developing individuals in different regions and various pollution sources. In addition, this review explores the effect of PM2.5 exposure to individuals of different ethnicities, genders, and socioeconomic levels on adverse birth outcomes and cardiopulmonary and neurological development. Furthermore, the molecular mechanisms involved in the adverse health effects of PM2.5 primarily encompass transcriptional and translational regulation, oxidative stress, inflammatory response, and epigenetic modulation. The primary findings and novel perspectives regarding the association between public health and PM2.5 were examined, highlighting the need for future studies to explore its sources, composition, and sex-specific effects. Additionally, further research is required to delve deeper into the more intricate underlying mechanisms to effectively prevent or mitigate the harmful effects of air pollution on human health.

AHR/cyp1b1 signaling-mediated extrinsic apoptosis contributes to 6PPDQ-induced cardiac dysfunction in zebrafish embryos

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPDQ) has raised significant concerns due to its widespread distribution and high toxicity to aquatic organisms. However, the cardiac developmental toxicity of 6PPDQ and the underlying mechanisms remain unclear. In this study, we observed no notable alterations in heart morphology or embryo survival in zebrafish embryos exposed to 6PPDQ (0.2-2000 μg/L) up to 3 days post-fertilization (dpf). However, concentrations at 2 μg/L or higher induced cardiac dysfunctions, leading to lethal effects at later stages (6-8 dpf). We further found that the aryl hydrocarbon receptor (AHR) inhibitor CH22351 attenuated 6PPDQ-induced cardiac dysfunctions, implicating the involvement of AHR signal pathway. Moreover, 6PPDQ exposure led to an overproduction of reactive oxygen species (ROS) and an upregulation of genes associated with oxidative stress (sod1, sod2, and nrf2a). This was accompanied by an increase in oxidative DNA damage and the induction of p53-dependent extrinsic apoptosis. Co-exposure to the ROS scavenger N-acetylcysteine effectively counteracted the DNA damage and apoptosis induced by 6PPDQ. Importantly, inhibition of AHR or its downstream target cyp1b1 attenuated 6PPDQ-induced oxidative stress, DNA damage, and apoptosis. In conclusion, our results provide evidence that 6PPDQ induces oxidative stress through the AHR/cyp1b1 signaling pathway, leading to DNA damage and extrinsic apoptosis, ultimately resulting in cardiac dysfunction.

Functional identification of long non-coding RNAs induced by PM2.5 in microglia through microarray analysis

As a dominating air pollutant, atmospheric fine particulate matter within 2.5 μm in diameter (PM2.5) has attracted increasing attention from the researchers all over the world, which will lead to various adverse effects on the central nervous system (CNS), yet the potential mechanism is unclear. In this study, the microglia (BV2 cell line) were exposed to different concentrations of PM2.5 (5, 10 and 20 μg/cm2) for 24 h. It was found that PM2.5 could result in adverse effects on microglia such as decreased cell viability, structural damage and even cell death. And it was reported that long non-coding RNAs (lncRNAs) could participate in multitudinous neurological diseases. Therefore, the microarray analysis was conducted in order to disclose the underlying neurotoxicity mechanism of PM2.5 by ascertaining the differentially expressed lncRNAs (DElncRNAs). The consequences indicated that the DElncRNAs were enriched in various biological pathways, including ferroptosis, IL-17 signaling pathway and NOD-like receptor signaling pathway. Moreover, the cis- and trans-regulated mRNAs by DElncRNAs as well as the corresponding transcriptional factors (TFs) were observed, such as CEBPA, MYC, MEIS1 and KLF4. In summary, our study supplies some candidate libraries and potential preventive target against PM2.5-induced toxicity through targeting lncRNAs. Furthermore, the post-transcriptional regulation will contribute to the future research on PM2.5-induced neurotoxicity.

PM2.5 induces cardiac defects via AHR-SIRT1-PGC-1α mediated mitochondrial damage

Recent evidence indicates that PM2.5 poses a risk for congenital heart diseases, but the mechanisms remain unclear. We hypothesized that AHR activated by PM2.5 might cause mitochondrial damage via PGC-1α dysregulation, leading to heart defects. We initially discovered that the PGC-1α activator ZLN005 counteracted cardiac defects in zebrafish larvae exposed to EOM (extractable organic matter) from PM2.5. Moreover, ZLN005 attenuated EOM-induced PGC-1α downregulation, mitochondrial dysfunction/biogenesis, and apoptosis. EOM exposure not only decreased PGC-1α expression levels, but suppressed its activity via deacetylation, and SIRT1 activity is required during both processes. We then found that SIRT1 expression levels and NAD+/NADH ratio were reduced in an AHR-dependent way. We also demonstrated that AHR directly suppressed the transcription of SIRT1 while promoted the transcription of TiPARP which consumed NAD+. In conclusion, our study suggests that PM2.5 induces mitochondrial damage and heart defects via AHR/SIRT1/PGC-1α signal pathway.

Unraveling the mechanism of quercetin alleviating perfluorooctane sulfonate-induced apoptosis in grass carp (Ctenopharyngodon idellus) hepatocytes: AMPK/mTOR-mediated mitophagy

Exposure to persistent new organic pollutants in the environment often leads to high mortality and causes serious economic losses to the aquaculture industry. Currently, perfluorooctane sulfonate (PFOS) is persistent and bio-accumulative in the environment, causing potential risks to aquatic ecosystems, but its toxicity mechanism to aquatic organisms is still unclear. As a natural flavonoid compound, quercetin (QU) has many biological activities such as anti-oxidation, anti-inflammatory, anti-apoptosis and immune regulation. Whether it can be used as a candidate medicine to alleviate PFOS toxicity needs to be further explored. Therefore, in this study, we treated (Ctenopharyngodon idellus) grass carp hepatocytes (L8824) with PFOS (200 μM) and/or QU (60 μM) for 24 h. The results showed that PFOS significantly increased the release of LDH and active oxygen (ROS) in L8824 cells, and led to the decrease of mitochondrial membrane potential (ΔΨm) and ATP content, the increase of mitochondrial ROS, the disorder of mitochondrial dynamics, and the initiation of Bcl-2/Bax-mediated apoptosis. Surprisingly, QU can alleviate the above PFOS-induced grass carp hepatocyte toxicity. In addition, in order to further explore the protective mechanism of QU, we used the molecular docking to predict the binding site between QU and AMPK, and found that there was a high binding capacity between QU and AMPK. In addition, we used Compound C (CC) and 3-Methyladenine (3-MA) to intervene. The results showed that CC and 3-MA intervention aggravated mitochondrial dysfunction and apoptosis factor expression in the QU+PFOS group. These data indicate that PFOS induces oxidative stress, mitochondrial dysfunction, and apoptosis. The regulation of AMPK/mTOR mediated mitophagy by QU may be a new therapeutic strategy to alleviate the hepatotoxicity of PFOS grass carp. This study provides theoretical basis and reference for exploring the toxic mechanism and biological toxic effects of PFOS, and provides a scheme for improving the economic benefits of aquaculture.

Heat stress suppresses MnSOD expression via p53-Sp1 interaction and induces oxidative stress damage in endothelial cells: Protective effects of MitoQ10 and Pifithrin-α

Aim

To investigate the mechanism of p53-mediated suppression of heat stress-induced oxidative stress damage by manganese superoxide dismutase (MnSOD) in endothelial cells (ECs).

Methods

Primary ECs isolated from mouse aortas were used to examine the effects of heat stress on vascular ECs viability and apoptosis. We measured MnSOD expression, reactive oxygen species (ROS) production, p53 expression, viability, and apoptosis of heat stress-induced ECs. We also tested the protective effects of MitoQ10, a mitochondrial-targeted antioxidant, and Pifithrin-α, a p53 inhibitor, in ECs from a mouse model of heat stroke.

Results

Heat stress increased cellular apoptosis, ROS production, and p53 expression, while reducing cellular viability and MnSOD expression in ECs. We also showed that the suppression of MnSOD expression by heat stress in ECs was mediated by interactions between p53 and Sp1. Furthermore, MitoQ10 and Pifithrin-α alleviated heat stress-induced oxidative stress and apoptosis in ECs.

Conclusion

Our results revealed that p53-mediated MnSOD downregulation is a key mechanism for heat stress-induced oxidative stress damage in ECs and indicated that MitoQ10 and Pifithrin-α could be potential therapeutic agents for heat stroke.

Identification of mitochondria-related action targets of quercetin in melanoma cells

Melanoma is a complex and genetically heterogeneous malignant tumor with high rates of mortality. Although current therapies provide a short-term clinical benefit, they are unable to cure the majority of patients with metastatic melanoma. Therefore, the investigation of pathological mechanisms and the development of new therapy strategies for melanoma are of great significance. Quercetin can effectively inhibit tumor growth in various tumors. However, the exact action mechanisms of quercetin against melanoma have not been comprehensively clarified, which limits its application. Accumulating evidence has suggested that the dysfunction of mitochondria is closely linked to carcinogenesis, and a better understanding of the regulation of mitochondria-related genes will shed light on providing new therapies for melanoma. In this study, we performed RNA-seq from melanoma B16-F1 cells treated with quercetin versus controls and screened for differentially expressed genes (DEGs). GO and KEGG enrichment analyses were performed, and a protein-protein interaction (PPI) network was constructed. Combining the results of RNA-seq, molecular docking, and bioinformatics analysis, we found six mitochondria-related genes, BTG2, CP, LRIG1, CYP1A1, GBP2, and MBNL1, which might be targets of quercetin in melanoma and provide an available targeting therapy strategy for melanoma.

The Reduction in the Mitochondrial Membrane Potential in Aging: The Role of the Mitochondrial Permeability Transition Pore

It is widely reported that the mitochondrial membrane potential, ∆Ψm, is reduced in aging animals. It was recently suggested that the lower ∆Ψm in aged animals modulates mitochondrial bioenergetics and that this effect is a major cause of aging since artificially increased ∆Ψm in C. elegans increased lifespan. Here, I critically review studies that reported reduction in ∆Ψm in aged animals, including worms, and conclude that many of these observations are best interpreted as evidence that the fraction of depolarized mitochondria is increased in aged cells because of the enhanced activation of the mitochondrial permeability transition pore, mPTP. Activation of the voltage-gated mPTP depolarizes the mitochondria, inhibits oxidative phosphorylation, releases large amounts of calcium and mROS, and depletes cellular NAD+, thus accelerating degenerative diseases and aging. Since the inhibition of mPTP was shown to restore ∆Ψm and to retard aging, the reported lifespan extension by artificially generated ∆Ψm in C. elegans is best explained by inhibition of the voltage-gated mPTP. Similarly, the reported activation of the mitochondrial unfolded protein response by reduction in ∆Ψm and the reported preservation of ∆Ψm in dietary restriction treatment in C. elegans are best explained as resulting from activation or inhibition of the voltage-gated mPTP, respectively.

AHR-mediated m6A RNA methylation contributes to PM2.5-induced cardiac malformations in zebrafish larvae

A growing body of evidence indicates that ambient fine particle matter (PM_2.5) exposure inhibits heart development, but the underlying mechanisms remain elusive. We hypothesized that m⁶A RNA methylation plays an important role in the cardiac developmental toxicity of PM_2.5. In this study, we demonstrated that extractable organic matter (EOM) from PM2.5 significantly decreased global m⁶A RNA methylation levels in the heart of zebrafish larvae, which were restored by the methyl donor, betaine. Betaine also attenuated EOM-induced ROS overgeneration, mitochondrial damage, apoptosis and heart defects. Furthermore, we found that the aryl hydrocarbon receptor (AHR), which was activated by EOM_, directly repressed the transcription of methyltransferases mettl14 and mettl3. EOM also induced genome-wide m⁶A RNA methylation changes, which led us to focus more on the aberrant m⁶A methylation changes that were subsequently alleviated by the AHR inhibitor, CH223191. In addition, we found that the expression levels of traf4a and bbc3, two apoptosis related genes, were upregulated by EOM but restored to control levels by the forced expression of mettl14. Moreover, knockdown of either traf4a or bbc3 attenuated EOM-induced ROS overproduction and apoptosis. In conclusion, our results indicate that PM_2.5 induces m⁶A RNA methylation changes via AHR-mediated mettl14 downregulation, which upregulates traf4a and bbc3, leading to apoptosis and cardiac malformations.