Benzene is a common environmental carcinogen that induces leukemia. Studies suggest that metabolic disorder has a relationship with the toxicity of benzene. Pyruvate kinase M2 (PKM2) is a key rate-limiting enzyme in glycolysis. However, the upstream and downstream regulatory mechanisms of PKM2 in benzene-induced hematotoxicity and the therapeutic effects of targeting PKM2 in vivo are unclear. This study aims to provide insights into the new mechanism of benzene-induced hematotoxicity and reveal the therapeutic significance of targeting PKM2. Herein, we demonstrated that PKM2-dependent glycolysis contributes to benzene-induced hematotoxicity by regulating inflammation reaction. Mechanistically, acetylated proteomics revealed that 1,4-benzoquinone (1,4-BQ) induced acetylation of PKM2 at position K66, and this modification contributed to the increase of PKM2 expression and can be inhibited by inhibition of acetyltransferase GCN5. Meanwhile, the elevated PKM2 was shown to prompt the activation of nuclear phosphorylated Stat3 (p-Stat3) and IL17A. Clinically, pharmacological inhibition of PKM2 alleviated the blood toxicity induced by benzene, which was mainly characterized by an increase in routine blood parameters and improvement of hematopoietic imbalance. Besides, elevated PKM2 is a promising biomarker in people occupationally exposed to benzene. Overall, we identified PKM2/p-Stat3/IL-17A axis participates in the hematotoxicity of benzene, and targeting PKM2 has certain therapeutic implications in hematologic diseases.

Fomesafen (FSA) is widely used in soybean fields for weed control. However, the persisting characteristics of FSA in the agricultural soil or water may become a hidden danger causing environmental pollution and phytotoxicity to succession crops. In this study, the growth and physiological responses of rice to FSA were investigated. It was found that the growth of rice seedlings was obviously inhibited by FSA exposure especially at over 0.1 mg L⁻¹. To gain an insight into the molecular mechanisms for the potential ecotoxicology, four libraries of rice roots and shoots exposed to FSA were created and subjected to the global RNA-sequencing (RNA-Seq) combined with HRLC-Q-TOF-MS/MS analytical technologies to comprehensively characterize the biochemical processes and catalytic reactions involved in FSA metabolism in rice. Compared with those without FSA, 499 and 450 up-regulated genes in roots and shoots with FSA were detected. Many of them were closely correlated with the tolerance to environmental stress, detoxification of xenobiotics and molecular metabolism process including cytochrome P450, glutathione S-transferases and acetyltransferase. A total of eight metabolites and fourteen conjugates in the reactive pathways of hydrolysis, substitution, reduction, methylation, glycosylation, acetylation, and malonylation were characterized by HRLC-Q-TOF-MS/MS. The relationship between the metabolized derivatives of FSA and enhanced expression the corresponding enzymatic regulators was established. This study will help understand the mechanisms and pathways of FSA metabolism and inspire the further research on FSA degradation in the paddy crops and environmental or health risks.

Artificial light at night (ALAN) exposes us to prolonged illumination, that adversely affects female reproduction. However, it remains to be clarified how prolonged light exposure affects oocyte meiotic maturation and quality. To this end, we exposed female mice to a constant light (CL) of 250 lux for different durations. Our findings showed that CL exposure for 7 weeks reduced the oocyte maturation rate. Meanwhile, CL exposure caused greater abnormalities in spindle assembly and chromosome alignment and a higher rate of oocyte aneuploidy than the regular light dark cycle. CL exposure also induced oxidative stress and caused mitochondrial dysfunction, which resulted in oocyte apoptosis and autophagy. Notably, our results showed that CL exposure reduced the levels of α-tubulin acetylation, DNA methylation at 5 mC, RNA methylation at m⁶A and histone methylation at H3K4me2 but increased the levels of histone methylation at H3K27me2 in oocytes. In summary, our findings demonstrate that constant bright light exposure causes oocyte meiotic defects and reduces cytoplasmic quality. These results extend the current understanding of ALAN-mediated defects in female reproduction.

N⁶-methyladenosine (m⁶A), the most abundant and reversible RNA modification, plays critical a role in tumorigenesis. However, whether m⁶A can regulate p53, a leading antitumor protein remains poorly understood. In this study, we explored the regulatory role of m⁶A on p53 activation using an arsenite-transformed keratinocyte model, the HaCaT-T cell line. We created the cell line by exposing human keratinocyte HaCaT cells to 1 μM arsenite for 5 months. We found that the cells exhibited an increased m⁶A level along with an aberrant expression of the methyltransferases, demethylase, and readers of m⁶A. Moreover, the cells exhibited decreased p53 activity and reduced p53 phosphorylation, acetylation, and transactivation with a high nucleus export rate of p53. Knockdown of the m⁶A methyltransferase, METTL3 significantly decreased m⁶A level, restoring p53 activation and inhibiting cellular transformation phenotypes in the arsenite-transformed cells. Further, using both a bioinformatics analysis and experimental approaches, we demonstrated that m⁶A downregulated the expression of the positive p53 regulator, PRDM2, through the YTHDF2-promoted decay of PRDM2 mRNAs. We showed that m⁶A upregulated the expression of the negative p53 regulator, YY1 and MDM2 through YTHDF1-stimulated translation of YY1 and MDM2 mRNA. Taken together, our study revealed the novel role of m⁶A in mediating arsenite-induced human keratinocyte transformation by suppressing p53 activation. This study further sheds light on the mechanisms of arsenic carcinogenesis via RNA epigenetics.

Even though clinical, epidemiological and toxicological studies have progressively provided a better knowledge of the underlying mechanisms by which air pollution-derived particulate matter (PM) exerts its harmful health effects, further in vitro studies on relevant cell systems are still needed. Hence, aiming of getting closer to the human in vivo conditions, primary human bronchial epithelial cells derived from normal subjects (NHBE) or sensitive chronic obstructive pulmonary disease (COPD)-diseased patients (DHBE) were differentiated at the air-liquid interface. Thereafter, they were repeatedly exposed to air pollution-derived PM2.5 to study the occurrence of some relevant genetic and/or epigenetic endpoints. Concentration-, exposure- and season-dependent increases of OH-B[a]P metabolites in NHBE, and to a lesser extent, COPD-DHBE cells were reported; however, there were more tetra-OH-B[a]P and 8-OHdG DNA adducts in COPD-DHBE cells. No increase in primary DNA strand break nor chromosomal aberration was observed in repeatedly exposed cells. Telomere length and telomerase activity were modified in a concentration- and exposure-dependent manner in NHBE and particularly COPD-DHBE cells. There were a global DNA hypomethylation, a P16 gene promoter hypermethylation, and a decreasing DNA methyltransferase activity in NHBE and notably COPD-DHBE cells repeatedly exposed. Changes in site-specific methylation, acetylation, and phosphorylation of histone H3 (i.e., H3K4me3, H3K9ac, H3K27ac, and H3S10ph) and related enzyme activities occurred in a concentration- and exposure-dependent manner in all the repeatedly exposed cells. Collectively, these results highlighted the key role played by genetic and even epigenetic events in NHBE and particularly sensitive COPD-DHBE cells repeatedly exposed to air pollution-derived PM2.5 and their different responsiveness. While these specific epigenetic changes have been already described in COPD and even lung cancer phenotypes, our findings supported that, together with genetic events, these epigenetic events could dramatically contribute to the shift from healthy to diseased phenotypes following repeated exposure to relatively low doses of air pollution-derived PM2.5.

N⁶-methyladenosine (m6A) modification, the most prevalent form of RNA methylation, modulates gene expression post-transcriptionally. Di-(2-ethylhexyl) phthalate (DEHP) is a common environmental endocrine disrupting chemical that induces testicular injury due to the inhibition of the demethylase fat mass and obesity-associated protein (FTO) and increases the m6A modification. How FTO-mediated m6A modification in testicular Leydig cell injury induced by DEHP remains unclear. Here, the TM3 Leydig cell line was treated with mono-(2-ethylhexyl) phthalate (MEHP), the main metabolite of DEHP in the body, as well as FB23-2, an inhibitor of FTO. Decreased levels of testosterone in the culture supernatant, significantly increased apoptosis, and a remarkable upregulation of global m6A modification were found in both TM3 cells treated with MEHP and FB23-2. Transcriptome sequencing showed that both treatments significantly induced apoptosis-associated gene expression. Methylated RNA immunoprecipitation sequencing showed that the Leydig cell injury induced by upregulated m6A modification could be associated with multiple physiological disorders, including histone acetylation, reactive oxygen species biosynthesis, MAPK signaling pathway, hormone secretion regulation, autophagy regulation, and male gonadal development. Overall, the inhibition of FTO-mediated up-regulation of m6A could be involved in MEHP-induced Leydig cell apoptosis.

Heart development requires a precise temporal regulation of gene expression in cardiomyoblasts. Therefore, the transcriptional changes in differentiating cells can lead to congenital heart diseases. Although the genetic mutations underlie most of these alterations, exposure to environmental contaminants, such as bisphenol A (BPA), has been recently considered as a risk factor as well. In this study we investigated the genotoxic and epigenotoxic effects of BPA throughout cardiomyocyte differentiation. H9c2 cells (rat myoblasts) were exposed to 10 and 30 μM BPA before and during the last two days of cardiac-driven differentiation. Then, we have analysed the phenotypic and molecular modifications (at transcriptional, genetic and epigenetic level). The results showed that treated myoblasts developed a skeletal muscle cell-like phenotype. The transcriptional changes induced by BPA in genes codifying proteins involved in heart differentiation and function depend on the window of exposure to BPA. The exposure before differentiation repressed the expression of heart transcription factors (Hand2 and Gata4), whereas exposure during differentiation reduced the expression of cardiac-specific genes (Tnnt2, Myom2, Sln, and Atp2a1). Additionally, significant effects were observed regarding DNA damage and histone acetylation levels after the two periods of BPA exposure: in cells exposed to the toxicant the percentage of DNA repair foci (formed by the co-localization of γH2AX and 53BP1) increased in a dose-dependent manner, whereas the treatment with the toxicant triggered a decrease in the epigenetic marks H3K9ac and H3K27ac. Our in vitro results reveal that BPA seriously interferes with the process of cardiomyocyte differentiation, which could be related to the reported in vivo effects of this toxicant on cardiogenesis.

Exposure to the emerging contaminant bisphenol A (BPA) is ubiquitous and associated with cardiovascular disorders. BPA effect as endocrine disruptor is widely known but other mechanisms underlying heart disease, such as epigenetic modifications, remain still unclear. A compound of green tea, epigallocatechin gallate (EGCG), may act both as anti-estrogen and as inhibitor of some epigenetic enzymes. The aims of this study were to analyze the molecular processes related to BPA impairment of heart development and to prove the potential ability of EGCG to neutralize the toxic effects caused by BPA on cardiac health. Zebrafish embryos were exposed to 2000 and 4000 μg/L BPA and treated with 50 and 100 μM EGCG. Heart malformations were assessed at histological level and by confocal imaging. Expression of genes involved in cardiac development, estrogen receptors and epigenetic enzymes was analyzed by qPCR whereas epigenetic modifications were evaluated by whole mount immunostaining. BPA embryonic exposure led to changes in cardiac phenotype, induced an overexpression of hand2, a crucial factor for cardiomyocyte differentiation, increased the expression of estrogen receptor (esr2b), promoted an overexpression of a histone acetyltransferase (kat6a) and also caused an increase in histone acetylation, both mechanisms being able to act in sinergy. EGCG treatment neutralized all the molecular alterations caused by BPA, allowing the embryos to go on with a proper heart development. Both molecular mechanisms of BPA action (estrogenic and epigenetic) likely lying behind cardiogenesis impairment were successfully counteracted by EGCG treatment.

Cadmium (Cd), which is considered a carcinogenic metal, promotes breast cancer (BC) progression, but the precise mechanism remains unclear. Herein, MCF-7 and T47-D cells were treated with 0.1, 1, and 10 μM cadmium chloride (CdCl₂) for 24, 48 and 72 h. In our study, Cd exposure significantly accelerated the proliferation, migration and invasion of MCF-7 and T47-D cells. Notably, Cd inhibited autophagic flux by suppressing ATG5-dependent autophagosome formation but had no significant effect on autophagosome-lysosome fusion and lysosomal function. The genetic enhancement of autophagy through ATG5 overexpression suppressed the Cd-mediated increases in proliferation, migration and invasion, which indicated a carcinogenic role of autophagy impairment in Cd-exposed BC cells. GSEA and GeneMANIA were utilized to demonstrate that the Cd-induced decrease in ACSS2 expression mechanistically inhibited ATG5-dependent autophagy in BC cells. Importantly, ACSS2 overexpression increased the level of H3K27 acetylation in the promoter region of ATG5, and this result maintained autophagic flux and abolished the Cd-induced increases in proliferation, migration and invasion. We also verified that the expression of ACSS2 in BC tissues was low and positively related to ATG5 expression. These findings indicated that the promoting effect of Cd on BC cell proliferation, migration and invasion through the impairment of ACSS2/ATG5-dependent autophagic flux suggests a new mechanism for BC cell proliferation and metastasis stimulated by Cd.

Perfluorooctane sulfonate (PFOS), an artificial perfluorinated compound, has been associated with male reproductive disorders. Histone modifications are important epigenetic mediators; however, the impact of PFOS exposure on testicular steroidogenesis through histone modification regulations remains to be elucidated. In this study, we examined the roles of histone modifications in regulating steroid hormone production in male rats chronically exposed to low-level PFOS. The results indicate that PFOS exposure significantly up-regulated the expressions of StAR, CYP11A1 and 3β-HSD, while CYP17A1 and 17β-HSD were down-regulated, thus contributing to the elevated progesterone and testosterone levels. Furthermore, PFOS significantly increased the histones H3K9me2, H3K9ac and H3K18ac while reduced H3K9me3 in rat testis. It is known that histone modifications are closely involved in gene transcription. Therefore, to investigate the association between histone modifications and steroidogenic gene regulation, the levels of these histone marks were further measured in steroidogenic gene promoter regions by ChIP. It was found that H3K18ac was augmented in Cyp11a1 promoter, and H3K9ac was increased in Hsd3b after PFOS exposure, which is proposed to result in the activation of CYP11A1 and 3β-HSD, respectively. To sum up, chronic low-level PFOS exposure activated key steroidogenic gene expression through enhancing histone acetylation (H3K9ac and H3K18ac), ultimately stimulating steroid hormone biosynthesis in rat testis.