Triclosan-induced abnormal expression of miR-30b regulates fto-mediated m6A methylation level to cause lipid metabolism disorder in zebrafish

Evidence of size-dependent toxicity of polystyrene nano- and microplastics in sea cucumber Apostichopus japonicus (Selenka, 1867) during the intestinal regeneration

Microplastics are ubiquitous pollutants in the global marine environment. However, few studies have adequately explored the different toxic mechanisms of microplastics (MPs) and nanoplastics (NPs) in aquatic organisms. The sea cucumber, Apostichopus japonicus, is a key organism in the marine benthic ecosystem due to its crucial roles in biogeochemical cycles and food web. This study investigated the bioaccumulation and adverse effects of polystyrene micro- and nanoplastics (PS-M/NPs) of different sizes (20 μm, 1 μm and 80 nm) in the regenerated intestine of A. japonicus using multi-omics analysis. The results showed that after 30-day exposure at the concentration of 0.1 mg L-1, PS-MPs and PS-NPs accumulated to 155.41-175.04 μg g-1 and 337.95 μg g-1, respectively. This excessive accumulation led to increased levels of antioxidases (SOD, CAT, GPx and T-AOC) and reduced activities of immune enzymes (AKP, ACP and T-NOS), indicating oxidative damage and compromised immunity in the regenerated intestine. PS-NPs had more profound negative impacts on cell proliferation and differentiation compared to PS-MPs. Transcriptomic analysis revealed that PS-NPs primarily affected pathways related to cellular components, e.g., ribosome, and oxidative phosphorylation. In comparison, PS-MPs had greater influences on actin-related organization and organic compound metabolism. In the PS-M/NPs-treated groups, differentially expressed metabolites were mainly amino acids, fatty acids, glycerol phospholipid, and purine nucleosides. Additionally, microbial community reconstruction in the regenerated intestine was severely disrupted by the presence of PS-M/NPs. In the PS-NPs group, Burkholderiaceae abundance significantly increased while Rhodobacteraceae abundance decreased. Correlation analyses demonstrated that intestinal regeneration of A. japonicus was closely linked to its enteric microorganisms. These microbiota-host interactions were notably affected by different PS-M/NPs, with PS-NPs exposure causing the most remarkable disruption of mutual symbiosis. The multi-omic approaches used here provide novel insights into the size-dependent toxicity of PS-M/NPs and highlight their detrimental effects on invertebrates in M/NPs-polluted marine benthic ecosystems.

Triclosan exposure causes abnormal bile acid metabolism through IL-1β-NF-κB-Fxr signaling pathway

Triclosan (TCS) is an eminent antibacterial agent. However, extensive usage causes potential health risks like hepatotoxicity, intestinal damage, kidney injury, etc. Existing studies suggested that TCS would disrupt bile acid (BA) enterohepatic circulation, but its toxic mechanism remains unclear. Hence, the current study established an 8-week TCS exposure model to explore its potential toxic mechanism. The results discovered 8 weeks consecutive administration of TCS induced distinct programmed cell death, inflammatory cell activation and recruitment, and excessive BA accumulation in liver. Furthermore, the expression of BA synthesis and transport associated genes were significantly dysregulated upon TCS treatment. Additional mechanism exploration revealed that Fxr inhibition induced by TCS would be the leading cause for unusual BA biosynthesis and transport. Subsequent Fxr up-stream investigation uncovered TCS exposure caused pyroptosis and its associated IL-1β would be the reason for Fxr reduction mediated by NF-κB. NF-κB blocking by dimethylaminoparthenolide ameliorated TCS induced BA disorder which confirmed the contribution of NF-κB in Fxr repression. To sum up, our findings conclud TCS-caused BA disorder is attributed to Fxr inhibition, which is regulated by the IL-1β-NF-κB signaling pathway. Hence, we suggest Fxr would be a potential target for abnormal BA stimulated by TCS and its analogs.

Cadmium exposure elicited dynamic RNA m6A modification and epi-transcriptomic regulation in the Pacific whiteleg shrimp Litopenaeus vannamei

N6-methyladenosine (m6A) methylation is the most prevalent post-transcriptional RNA modification in eukaryotic organisms, but its roles in the regulation of physiological resistance of marine crustaceans to heavy metal pollutants are poorly understood. In this study, the transcriptome-wide m6A RNA methylation profiles and dynamic m6A changes induced by acute Cd2+ exposure in the the pacific whiteleg shrimp Litopenaeus vannamei were comprehensively analyzed. Cd2+ toxicity caused a significant reduction in global RNA m6A methylation level, with major m6A regulators including the m6A methyltransferase METTL3 and the m6A binding protein YTHDF2 showing declined expression. Totally, 11,467 m6A methylation peaks from 6415 genes and 17,291 peaks within 7855 genes were identified from the Cd2+ exposure group and the control group, respectively. These m6A peaks were predominantly enriched in the 3' untranslated region (UTR) and around the start codon region of the transcripts. 7132 differentially expressed genes (DEGs) and 7382 differentially m6A-methylated genes (DMGs) were identified. 3186 genes showed significant changes in both gene expression and m6A methylation levels upon cadmium exposure, and they were related to a variety of biological processes and gene pathways. Notably, an array of genes associated with antioxidation homeostasis, transmembrane transporter activity and intracellular detoxification processes were significantly enriched, demonstrating that m6A modification may mediate the physiological responses of shrimp to cadmium toxicity via regulating ROS balance, Cd2+ transport and toxicity mitigation. The study would contribute to a deeper understanding of the evolutionary and functional significance of m6A methylation to the physiological resilience of decapod crustaceans to heavy metal toxicants.

Risk of Fat Mass- and Obesity-Associated Gene-Dependent Obesogenic Programming by Formula Feeding Compared to Breastfeeding

It is the purpose of this review to compare differences in postnatal epigenetic programming at the level of DNA and RNA methylation and later obesity risk between infants receiving artificial formula feeding (FF) in contrast to natural breastfeeding (BF). FF bears the risk of aberrant epigenetic programming at the level of DNA methylation and enhances the expression of the RNA demethylase fat mass- and obesity-associated gene (FTO), pointing to further deviations in the RNA methylome. Based on a literature search through Web of Science, Google Scholar, and PubMed databases concerning the dietary and epigenetic factors influencing FTO gene and FTO protein expression and FTO activity, FTO's impact on postnatal adipogenic programming was investigated. Accumulated translational evidence underscores that total protein intake as well as tryptophan, kynurenine, branched-chain amino acids, milk exosomal miRNAs, NADP, and NADPH are crucial regulators modifying FTO gene expression and FTO activity. Increased FTO-mTORC1-S6K1 signaling may epigenetically suppress the WNT/β-catenin pathway, enhancing adipocyte precursor cell proliferation and adipogenesis. Formula-induced FTO-dependent alterations of the N6-methyladenosine (m6A) RNA methylome may represent novel unfavorable molecular events in the postnatal development of adipogenesis and obesity, necessitating further investigations. BF provides physiological epigenetic DNA and RNA regulation, a compelling reason to rely on BF.

Analysis of key circRNA events in the AOP framework of TCS acting on zebrafish based on the data-driven

Triclosan (TCS) is a broad-spectrum antibiotic widely used in various personal care products. Research has found that exposure to TCS can cause toxic effects on organisms including neurotoxicity, cardiotoxicity, disorders of lipid metabolism, and abnormal vascular development, and the corresponding toxic mechanisms are gradually delving into the level of abnormal expression of miRNA regulating gene expression. Although the downstream mechanism of TCS targeting miRNA abnormal expression to induce toxicity is gradually improving, its upstream mechanism is still in a fog. Starting from the abnormal expression data of circRNA in zebrafish larvae induced by TCS, this study conducted a hierarchical analysis of the expression levels of all circRNAs, differential circRNAs, and trend circRNAs, and identified 29 key circRNA events regulating miRNA abnormal expression. In combination with GO and KEGG, the effects of TCS exposure were analyzed from the function and signaling pathway of the corresponding circRNA host gene. Furthermore, based on existing literature evidence about the biological toxicity induced by TCS targeting miRNA as data support, a competing endogenous RNAs (ceRNA) network characterizing the regulatory relationship between circRNA and miRNA was constructed and optimized. Finally, a comprehensive Adverse Outcome Pathway (AOP) framework of multiple levels of events including circRNA, miRNA, mRNA, pathway, and toxicity endpoints was established to systematically elucidate the toxic mechanism of TCS. Moreover, the rationality of the AOP framework was verified from the expression level of miRNA and adverse outcomes such as neurotoxicity, cardiotoxicity, oxidative stress, and inflammatory response by knockdown of circRNA48. This paper not only provides the key circRNA events for exploring the upstream mechanism of miRNA regulating gene expression but also provides an AOP framework for comprehensively demonstrating the toxicity mechanism of TCS on zebrafish, which is a theoretical basis for subsequent hazard assessment and prevention and control of TCS.

Comparative impact of pristine and aged microplastics with triclosan on lipid metabolism in larval zebrafish: Unveiling the regulatory role of miR-217

The prevalence of microplastics (MPs), especially aged particles, interacting with contaminants like triclosan (TCS), raises concerns about their toxicological effects on aquatic life. This study focused on the impact of aged polyamide (APA) MPs and TCS on zebrafish lipid metabolism. APA MPs, with rougher surfaces and lower hydrophobicity, exhibited reduced TCS adsorption than unaged polyamide (PA) MPs. Co-exposure to PA/APA MPs and TCS resulted in higher TCS accumulation in zebrafish larvae, notably more with PA than APA. Larvae exposed to PA + TCS exhibited greater oxidative stress, disrupted lipid metabolism, and altered insulin pathway genes than those exposed to TCS. However, these negative effects were lessened in the APA + TCS group. Through miRNA-seq and miR-217 microinjection, it was revealed that PA + TCS co-exposure upregulated miR-217, linked to lipid metabolic disorders in zebrafish. Moreover, molecular docking showed stable interactions formed between PA, TCS, and the insulin signaling protein Pik3r2. This study demonstrated that PA and TCS co-exposure significantly inhibited the insulin signaling in zebrafish, triggering lipid metabolism dysregulation mediated by miR-217 upregulation, while APA and TCS co-exposure alleviated these disruptions. This research underscored the ecological and toxicological risks of aged MPs and pollutants in aquatic environments, providing crucial insights into the wider implications of MPs pollution.

Nurturing gut health: role of m6A RNA methylation in upholding the intestinal barrier

The intestinal lumen acts as a critical interface connecting the external environment with the body's internal state. It's essential to prevent the passage of harmful antigens and bacteria while facilitating nutrient and water absorption. The intestinal barriers encompass microbial, mechanical, immunological, and chemical elements, working together to maintain intestinal balance. Numerous studies have associated m6A modification with intestinal homeostasis. This review comprehensively outlines potential mechanisms through which m6A modification could initiate, exacerbate, or sustain barrier damage from an intestinal perspective. The pivotal role of m6A modification in preserving intestinal equilibrium provides new insights, guiding the exploration of m6A modification as a target for optimizing preventive and therapeutic strategies for intestinal homeostasis.

Toxic effects of triclosan on hepatic and intestinal lipid accumulation in zebrafish via regulation of m6A-RNA methylation

Triclosan (TCS), recognized as an endocrine disruptor, has raised significant concerns due to its widespread use and potential health risks. To explore the impact of TCS on lipid metabolism, both larval and adult zebrafish were subjected to acute and chronic exposure to TCS. Through analyzes of biochemical and physiological markers, as well as Oil Red O (ORO) and hematoxylin and eosin (H&E) staining, our investigation revealed that TCS exposure induced hepatic and intestinal lipid accumulation in larval and adult zebrafish, leading to structural damage and inflammatory responses in these tissues. The strong affinity of TCS with PPARγ and subsequent pathway activation indicate that PPARγ pathway plays a crucial role in TCS-induced lipid buildup. Furthermore, we observed a decrease in m6A-RNA methylation levels in the TCS-treated group, which attributed to the increased activity of the demethylase FTO and concurrent suppression of the methyltransferase METTL3 gene expression by TCS. The alteration in methylation dynamics is identified as a potential underlying mechanism behind TCS-induced lipid accumulation. To address this concern, we explored the impact of folic acid-a methyl donor for m6A-RNA methylation-on lipid accumulation in zebrafish. Remarkably, folic acid administration partially alleviated lipid accumulation by restoring m6A-RNA methylation. This restoration, in turn, contributed to a reduction in inflammatory damage observed in both the liver and intestines. Additionally, folic acid partially mitigates the up-regulation of PPARγ and related genes induced by TCS. These findings carry substantial implications for understanding the adverse effects of environmental pollutants such as TCS. They also emphasize the promising potential of folic acid as a therapeutic intervention to alleviate disturbances in lipid metabolism induced by environmental pollutants.

Chronic administration of triclosan leads to liver fibrosis through hepcidin-ferroportin axis-mediated iron overload

Triclosan (TCS) has been manufactured as an antibacterial compound for half a century. Currently, it is widely used in various personal care products; however, its potential adverse effects raise a lot of attention. Here, we create a long-term oral administration mouse model and identify the corresponding hepatotoxicity of TCS. We discover that daily intragastric administration of 10 mg/kg TCS to mice for 12 weeks results in severe hepatic fibrosis. Further study displays that hepatic iron increased 18%, 23% and 29% upon oral TCS treatment for 4, 8 and 12 weeks, respectively. Accompanied by hepatic iron variation, splenic and duodenal iron are increased, which indicates systemic iron disorder. Not only excessive iron accumulated in the liver, abnormal hepatic malondialdehyde, prostaglandin synthase 2 and glutathione peroxidase 4 are pointed to ferroptosis. Additional study uncovers that hepcidin expression increases 7%, 10%, 4% in serum and 2.4-, 4.8-, and 2.3-fold on transcriptional levels upon TCS exposure for 4, 8 and 12 weeks, individually. Taken together, the mice in the TCS-treated group show disordered systemic iron homeostasis via the upregulated hepatic hepcidin-ferroportin axis. Meanwhile, both hepatic iron overload (systemic level) and hepatocyte ferroptosis (cellular level) are accused of TCS-induced liver fibrosis. Ferriprox®, an iron scavenger, significantly ameliorates TCS-induced liver fibrosis. In summary, this study confirms the impact of TCS on liver fibrosis; a critical signal pathway is also displayed. The significance of the current study is to prompt us to reevaluate the "pros and cons" of TCS applications.

N6-methyladenosine modification in ischemic stroke: Functions, regulation, and therapeutic potential

N6-methyladenosine (m6A) modification is the most frequently occurring internal modification in eukaryotic RNAs. By modulating various aspects of the RNA life cycle, it has been implicated in a wide range of pathological and physiological processes associated with human diseases. Ischemic stroke is a major cause of death and disability worldwide with few treatment options and a narrow therapeutic window, and accumulating evidence has indicated the involvement of m6A modifications in the development and progression of this type of stroke. In this review, which provides insights for the prevention and clinical treatment of stroke, we present an overview of the roles played by m6A modification in ischemic stroke from three main perspectives: (1) the association of m6A modification with established risk factors for stroke, including hypertension, diabetes mellitus, hyperlipidemia, obesity, and heart disease; (2) the roles of m6A modification regulators and their functional regulation in the pathophysiological injury mechanisms of stroke, namely oxidative stress, mitochondrial dysfunction, endothelial dysfunction, neuroinflammation, and cell death processes; and (3) the diagnostic and therapeutic potential of m6A regulators in the treatment of stroke.

Deciphering the molecular mediators of triclosan-induced lipid accumulation: Intervention via short-chain fatty acids and miR-101a

As a potential environmental obesogen, triclosan (TCS) carries inherent risks of inducing obesity and metabolic disorders. However, the underlying molecular mechanisms behind the lipid metabolism disorder induced by TCS have remained elusive. Through a fusion of transcriptomics and microRNA target prediction, we hypothesize that miR-101a as a responsive miRNA to TCS exposure in zebrafish, playing a central role in disturbing lipid homeostasis. As an evidence, TCS exposure triggers a reduction in miR-10a expression that accompanied by elevation of genes linked to regulation of lipid homeostasis. Through precision-controlled interventions involving miRNA expression modulation, we discovered that inhibition of miR-101a enhanced expression of its target genes implicated in lipid homeostasis, subsequently triggering excessive fat accumulation. Meanwhile, the overexpression of miR-101a acts as a protective mechanism, counteracting the lipid metabolism disorder induced by TCS in the larvae. Notably, the combination of short-chain fatty acids (SCFAs) emerged as a potential remedy to alleviate TCS-induced lipid accumulation partially by counteracting the decline in miR-101a expression induced by TCS. These revelations provide insight into a prospective molecular framework underlying TCS-triggered lipid metabolism disorders, thereby paving the way for pre-emptive strategies in combating the ramifications of TCS pollution.

Chronic triclosan exposure induce impaired glucose tolerance by altering the gut microbiota

Triclosan (TCS) is an antimicrobial compound incorporated into more than 2000 consumer products. This compound is frequently detected in the human body and causes ubiquitous contamination in the environment, thereby raising concerns about its impact on human health and environmental pollution. Here, we demonstrated that 20 weeks' exposure of TCS drove the development of glucose intolerance by inducing compositional and functional alterations in intestinal microbiota in rats. Fecal-transplantation experiments corroborated the involvement of gut microbiota in TCS-induced glucose-tolerance impairment. 16S rRNA gene-sequencing analysis of cecal contents showed that TCS disrupted the gut microbiota composition in rats and increased the ratio of Firmicutes to Bacteroidetes. Cecal metabolomic analyses detected that TCS altered host metabolic pathways that are linked to host glucose and amino acid metabolism, particularly branched-chain amino acid (BCAA) biosynthesis. BCAA measurement confirmed the increase in serum BCAAs in rats exposed to TCS. Western blot and immunostaining results further confirmed that elevated BCAAs stimulated mTOR, a nutrient-sensing complex, and following IRS-1 serine phosphorylation, resulted in insulin resistance and glucose intolerance. These results suggested that TCS may induce glucose metabolism imbalance by regulating BCAA concentration by remodeling the gut microbiota.

N6-methyladenosine RNA modification in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, influencing numerous regulatory axes and extrahepatic vital organs. The molecular mechanisms that lead to the progression of NAFLD remain unclear and knowledge on the pathways causing hepatocellular damage followed by lipid accumulation is limited. Recently, a number of studies have shown that mRNA N6-methyladenosine (m6A) modification contributes to the progression of NAFLD. In this review, we summarize current knowledge on m6A modification in the metabolic processes associated with NAFLD and discuss the challenges of and prospects for therapeutic avenues based on m6A regulation for the treatment of liver disease.

Mechanistic illustration on lipid-metabolism disorders induced by triclosan exposure from the viewpoint of m6A-RNA epigenetic modification

As a typically anthropogenic contaminant, the toxicity effects of triclosan (TCS) were investigated in-depth from the viewpoint of m6A-pre-miRNAs modification. Based on miRNAs high-throughput sequencing, we unravelled the underlying molecular mechanisms regarding TCS-induced lipid-metabolism functional disorders. TCS exposure caused severe lipid accumulation in 120 hpf zebrafish liver and reduced their locomotor activity. Both bioinformatics analysis and experimental validation verified that TCS targeted miR-27b up-regulation to further trigger lipid-metabolism disorders and developmental malformations, including shortened body length, yolk cysts, curved spine and delayed yolk absorption. TCS exposure and miR-27b upregulation both caused the enhanced levels of triglyceride and total cholesterol. Knockdown and overexpression of miR-27b regulated the expression changes of several functional genes related to downstream lipid metabolism of miR-27b, and most downstream target genes of miR-27b were suppressed and enriched in the AMPK signaling pathway. The experiments of pathway inhibitors and agonists further evidenced that TCS caused lipid-metabolism disorders by suppressing the AMPK signaling pathway. In upstream of miR-27b, TCS decreased total m6A-RNA level by targeting upregulation of demethylase and downregulation of methylase reader ythdf1. Molecular docking and ythdf1 siRNA interference further confirmed that TCS targeted the expression change of ythdf1. Under ythdf1 knockdown in upstream of miR-27b, both abnormal lipid metabolism and miR-27b upregulation highlighted that TCS-induced lipid-metabolism disorders were attributable to the decreasing m6A-RNA methylation levels in vivo. These perspectives provide an innovative idea for prevention and treatment of the lipid metabolism-related diseases and these findings open a novel avene for TCS's risk assessment and early intervention of the contaminant.

Dynamic N6-methyladenosine RNA methylation landscapes reveal epi-transcriptomic modulation induced by ammonia nitrogen exposure in the Pacific whiteleg shrimp Litopenaeus vannamei

Despite the versatility of RNA m⁶A methylation in regulating various biological processes, its involvement in the physiological response to ammonia nitrogen toxicity in decapod crustaceans like shrimp remains enigmatic. Here, we provided the first characterization of dynamic RNA m⁶A methylation landscapes induced by toxic ammonia exposure in the Pacific whiteleg shrimp Litopenaeus vannamei. The global m⁶A methylation level showed significant decrease following ammonia exposure, and most of the m⁶A methyltransferases and m⁶A binding proteins were significantly repressed. Distinct from many well-studied model organisms, m⁶A methylated peaks in the transcriptome of L. vannamei were enriched not only near the termination codon and in the 3' untranslated region (UTR), but also around the start codon and in the 5' UTR. Upon ammonia exposure, 11,430 m⁶A peaks corresponding to 6113 genes were hypo-methylated, and 5660 m⁶A peaks from 3912 genes were hyper-methylated. The differentially methylated genes showing significant changes in expression were over-represented by genes associated with metabolism, cellular immune defense and apoptotic signaling pathways. Notably, the m⁶A-modified ammonia-responsive genes encompassed a subset of genes related to glutamine synthesis, purine conversion and urea production, implying that m⁶A methylation may modulate shrimp ammonia stress responses partly through these ammonia metabolic processes.

Zebrafish facilitate non-alcoholic fatty liver disease research: Tools, models and applications

Non-alcoholic fatty liver disease (NAFLD) has become an increasingly epidemic metabolic disease worldwide. NAFLD can gradually deteriorate from simple liver steatosis, inflammation and fibrosis to liver cirrhosis and/or hepatocellular carcinoma. Zebrafish are vertebrate animal models that are genetically and metabolically conserved with mammals and have unique advantages such as high fecundity, rapid development ex utero and optical transparency. These features have rendered zebrafish an emerging model system for liver diseases and metabolic diseases favoured by many researchers in recent years. In the present review, we summarize a series of tools for zebrafish NAFLD research and the models established through different dietary feeding, hepatotoxic chemical treatments and genetic manipulations via transgenic or genome editing technologies. We also discuss how zebrafish models facilitate NAFLD studies by providing novel insights into NAFLD pathogenesis, toxicology research, and drug evaluation and discovery.

Adverse effects of triclosan exposure on health and potential molecular mechanisms

With the COVID-19 pandemic, the use of disinfectants has grown significantly around the world. Triclosan (TCS), namely 5-chloro-2-(2,4-dichlorophenoxy) phenol or 2,4,4'-trichloro-2'-hydroxydiphenyl ether, is a broad-spectrum, lipophilic, antibacterial agent that is extensively used in multifarious consumer products. Due to the widespread use and bioaccumulation, TCS is frequently detected in the environment and human biological samples. Accumulating evidence suggests that TCS is considered as a novel endocrine disruptor and may have potential unfavorable effects on human health, but studies on the toxic effect mediated by TCS exposure as well as its underlying mechanisms of action are relatively sparse. Therefore, in this review, we attempted to summarize the potential detrimental effects of TCS exposure on human reproductive health, liver function, intestinal homeostasis, kidney function, thyroid endocrine, and other tissue health, and further explore its mechanisms of action, thereby contributing to the better understanding of TCS characteristics and safety. Moreover, our work suggested the need to further investigate the biological effects of TCS exposure at the metabolic level in vivo.

Mechanistic exploration on neurodevelopmental toxicity induced by upregulation of alkbh5 targeted by triclosan exposure to larval zebrafish

Because triclosan (TCS) has been confirmed to cause severe neurotoxicity, it is urgent to disclose the underlying toxicity mechanisms at varying levels. TCS exposure resulted in a series of malformations in larval zebrafish, including reduced neurons, blood-vessel ablation and abnormal neurobehavior. Apoptosis staining and the upregulated expression of proapoptotic genes demonstrated that TCS induced neuronal apoptosis and neurotransmitter disorders. By integrating RT-qPCR analysis with the effects of pathway inhibitors and agonists, we found that TCS triggered abnormal regulation of neuron development-related functional genes, and suppressed the BDNF/TrkB signaling pathway. TCS inhibited total m⁶A-RNA modification level by activating the demethylase ALKBH5, and induced neurodevelopmental toxicity based on the knockdown experiments of alkbh5 and molecular docking. The main novelties of this study lies in: (1) based on specific staining and transgenic lines, the differential neurotoxicity effects of TCS were unravelled at individual, physiological, biochemical and molecular levels in vivo; (2) from a epigenetics viewpoint, the decreasing m⁶A methylation level was confirmed to be mediated by alkbh5 upregulation; and (3) both homology modeling and molecular docking evidenced the targeting action of TCS on ALKBH5 enzyme. These findings open a novel avene for TCS's risk assessment and early intervention of the contaminant-sourcing diseases.

Molecular mechanisms of environmental exposures and human disease

A substantial proportion of disease risk for common complex disorders is attributable to environmental exposures and pollutants. An appreciation of how environmental pollutants act on our cells to produce deleterious health effects has led to advances in our understanding of the molecular mechanisms underlying the pathogenesis of chronic diseases, including cancer and cardiovascular, neurodegenerative and respiratory diseases. Here, we discuss emerging research on the interplay of environmental pollutants with the human genome and epigenome. We review evidence showing the environmental impact on gene expression through epigenetic modifications, including DNA methylation, histone modification and non-coding RNAs. We also highlight recent studies that evaluate recently discovered molecular processes through which the environment can exert its effects, including extracellular vesicles, the epitranscriptome and the mitochondrial genome. Finally, we discuss current challenges when studying the exposome - the cumulative measure of environmental influences over the lifespan - and its integration into future environmental health research.

The biological functions of maternal-derived extracellular vesicles during pregnancy and lactation and its impact on offspring health

During pregnancy and lactation, mothers provide not only nutrients, but also many bioactive components for their offspring through placenta and breast milk, which are essential for offspring development. Extracellular vesicles (EVs) are nanovesicles containing a variety of biologically active molecules and participate in the intercellular communication. In the past decade, an increasing number of studies have reported that maternal-derived EVs play a crucial role in offspring growth, development, and immune system establishment. Hereby, we summarized the characteristics of EVs; biological functions of maternal-derived EVs during pregnancy, including implantation, decidualization, placentation, embryo development and birth of offspring; biological function of breast milk-derived EVs (BMEs) on infant oral and intestinal diseases, immune system, neurodevelopment, and metabolism. In summary, emerging studies have revealed that maternal-derived EVs play a pivotal role in offspring health. As such, maternal-derived EVs may be used as promising biomarkers in offspring disease diagnosis and treatment. However, existing research on maternal-derived EVs and offspring health is largely limited to animal and cellular studies. Evidence from human studies is needed.

Interaction between N6-methyladenosine (m6A) modification and environmental chemical-induced diseases in various organ systems

A wide variety of chemicals are ubiquitous in the environment and thus exposure to these environmental chemicals poses a serious threat to public health. Particularly, environmental factors such as air pollution, heavy metals, and endocrine-disrupting chemicals (EDCs) can lead to diseases in various organ systems. Recent research in environmental epigenetics has demonstrated that N6-methyladenosine (m6A) modification is a key mechanism of environment-related diseases. m6A modification is the most abundant chemical modification in mRNAs, which can specifically regulate gene expression by affecting RNA translation, stability, processing, and nuclear export. In this review, we discussed how environmental chemicals affected m6A modification and mediated environment-related disease occurrence by classifying the diseases of various systems. Here, we conclude that environmental chemicals alter the levels of m6A and its modulators, which then participate in the occurrence of diseases in various systems by regulating gene expression and downstream signaling pathways such as METTL3/m6A ZBTB4/YTHDF2/EZH2, Foxo3a/FTO/m6A ephrin-B2/YTHDF2, and HIF1A/METTL3/m6A BIRC5/IGF2BP3/VEGFA. Considering the significant role of m6A and its modulators in response to environmental chemicals, they are expected to be used as biomarkers of environment-related diseases. Additionally, targeting m6A modulators using small molecule inhibitors and activators is expected to be a new method for the treatment of environment-related diseases. This review systematically and comprehensively clarifies the important role of m6A in diseases caused by environmental chemicals, thus establishing a scientific basis for the treatment of diseases in various organ systems.

Transcriptome-wide m6A modification mediates cardiotoxicity in mice after chronic exposure to microplastics

The widespread presence of microplastics (MPs) has garnered attention owing to their possible adverse effects. However, the cardiotoxicity of MPs and their underlying mechanism remains unclear. N6-methyladenosine (m6A) modification contributes to post-transcriptional modulation of gene expression, but whether this modification is relevant to MP-induced cardiotoxicity is unknown. First, we detected damage to the myocardial tissue among MP-exposed and -unexposed (control) mice by staining them with hematoxylin and eosin, Masson trichrome, and Oil Red O. Then, we comprehensively measured the transcriptome-wide m6A methylome and m6A-altered genes using high-throughput sequencing assays, such as methylated RNA immunoprecipitation sequencing and RNA sequencing. Our data indicated MP-induced myocardial inflammatory injury and histological alterations in vivo, evidenced by the severity of cardiac fibrosis and increased lipid accumulation. We found 878 increased and 316 decreased methylation peaks mostly distributed in the 3' UTR among the MP-exposed group compared with the control group. We found 779 upregulated and 340 downregulated genes in the MP-exposed group. In addition, conjoint analysis of results from the two high-throughput sequencings showed that 109 and 11 hypermethylated genes were upregulated and downregulated, respectively; 12 and 21 hypomethylated genes were upregulated and downregulated, respectively. Results of the cross-link analysis showed that several potential signals, such as ECM-receptor interactions, cell adhesion molecules, cytokine-cytokine receptor interactions, and NF-κB signaling, contributed to MP-induced cardiotoxicity. Our findings indicated that m6A modifications of genes were involved in MP-induced cardiotoxicity and reported new information regarding the chronic cardiotoxicity caused by MP exposure in mice.

The Role of Cow's Milk Consumption in Breast Cancer Initiation and Progression

PURPOSE OF REVIEW

This review evaluates cow milk's impact on breast carcinogenesis by linking recent epidemiological evidence and new insights into the molecular signaling of milk and its constituents in breast cancer (BCa) pathogenesis.

RECENT FINDINGS

Recent prospective cohort studies support the association between cow's milk consumption and the risk of estrogen receptor-α-positive (ER⁺) BCa. Milk is a complex biological fluid that increases systemic insulin-like growth factor 1 (IGF-1), insulin and estrogen signaling, and interacting hormonal promoters of BCa. Further potential oncogenic components of commercial milk include exosomal microRNAs (miR-148a-3p, miR-21-5p), bovine meat and milk factors, aflatoxin M1, bisphenol A, pesticides, and micro- and nanoplastics. Individuals with BRCA1 loss-of-function mutations and FTO and IGF1 gain-of-function polymorphisms enhancing IGF-1/mTORC1 signaling may be at increased risk for milk-induced ER⁺ BCa. Recent prospective epidemiological and pathobiochemical studies identify commercial milk consumption as a critical risk factor of ER⁺ BCa. Large meta-analyses gathering individuals of different ethnic origins with milk derived from dairy cows of varying genetic backgrounds and diverse feeding procedures as well as missing data on thermal processing of milk (pasteurization versus ultra-heat treatment) make multi-national meta-analyses unsuitable for BCa risk estimations in susceptible populations. Future studies are required that consider all vulnerable periods of breast carcinogenesis to cow's milk exposure, beginning during the perinatal period and puberty, since these are the most critical periods of mammary gland morphogenesis. Notwithstanding the need for better studies including detailed information on milk processing and vulnerable periods of human breast carcinogenesis, the available evidence suggests that dietary guidelines on milk consumption may have to be reconsidered.

METTL3 contributes to slow transit constipation by regulating miR-30b-5p/PIK3R2/Akt/mTOR signaling cascade through DGCR8

BACKGROUND

N6-methyladenosine (m6A) is the most prevalent methylation modification of eukaryotic RNA, and methyltransferase-like 3 (METTL3) plays a vital role in multiple cell functions. This study aimed to investigate the role of m6A methylase METTL3 in slow transit constipation (STC).

MATERIAL AND METHOD

The expression of METTL3 and DGCR8 was measured in STC tissues and glutamic acid-induced interstitial cells of Cajal (ICCs). The effects of METTL3, miR-30b-5p, and DGCR8 on the biological characteristics of ICCs were investigated on the basis of loss-of-function analyses. Luciferase reporter assay was used to identify the direct binding sites of miR-30b-5p with PIK3R2.

RESULTS

The results showed that the METTL3, DGCR8, miR-30b-5p, and the methylation level of m6A were significantly increased in STC tissues and glutamic acid-induced ICCs. Silencing of METTL3 and miR-30b-5p inhibited apoptosis, autophagy, and pyroptosis of glutamic acid-induced ICCs. Moreover, overexpression of miR-30b-5p reversed the cytoprotection of METTL3 knockdown in glutamic acid-induced ICCs. Besides, DGCR8 knockdown could facilitate cell growth and decrease apoptotic glutamic acid-induced ICCs. Mechanically, we illustrated that METTL3 in glutamic acid-induced ICCs significantly accelerated the maturation of pri-miR-30b-5p by m6A methylation modification, resulting in the reduction of PIK3R2, which results in the inhibition of PI3K/Akt/mTOR pathway and ultimately leads to the cell death of STC.

CONCLUSIONS

Collectively, these data demonstrated that METTL3 promoted the apoptosis, autophagy, and pyroptosis of glutamic acid-induced ICCs by interacting with the DGCR8 and successively modulating the miR-30b-5p/PIK3R2 axis in an m6A-dependent manner, and METTL3 may be a potential therapeutic target for STC.

The role of N6-methyladenosine methylation in environmental exposure-induced health damage

The health risks caused by environmental pollution have long been of substantial concern. With the development of epigenetics, a large number of studies have demonstrated that N6-methyladenosine (m6A) modification is involved in the regulation of various important life activities associated with various diseases. Recent studies have revealed that m6A plays a key role in health damage caused by environmental exposure by regulating post-transcriptional gene expression. Therefore, our study outlined the effects of environmental pollutant exposure on m6A methylation and its regulator levels. Moreover, we found that m6A methylation modifications were involved in the development of various health damages by regulating important life activities in vivo, such as reactive oxygen species imbalance, apoptosis, epithelial-mesenchymal transition (EMT), and inflammatory processes. More importantly, we delved into the regulatory mechanisms of m6A methylation dysregulation in environmental pollution-induced diseases. Finally, by examining the published literature, we found that methyltransferase-like protein 3 (METTL3) and fat mass- and obesity-associated protein (FTO) were potentially used as biomarkers of health damage induced by particulate matter exposure and heavy metal exposure, respectively. The current studies on regulators of METTL3 and FTO were more promising to bring new perspectives for the treatment of environmental health-related diseases.

Dunaliella salina Microalga Restores the Metabolic Equilibrium and Ameliorates the Hepatic Inflammatory Response Induced by Zinc Oxide Nanoparticles (ZnO-NPs) in Male Zebrafish

Microalgae are rich in bioactive compounds including pigments, proteins, lipids, polyunsaturated fatty acids, carbohydrates, and vitamins. Due to their non-toxic and nutritious characteristics, these are suggested as important food for many aquatic animals. Dunaliella salina is a well-known microalga that accumulates valuable amounts of carotenoids. We investigated whether it could restore the metabolic equilibrium and mitigate the hepatic inflammation induced by zinc oxide nanoparticles (ZnO-NPs) using male zebrafish which were exposed to 1/5^th 96 h-LC₅₀ for 4 weeks, followed by dietary supplementation with D. salina at two concentrations (15% and 30%) for 2 weeks. Collectively, ZnO-NPs affected fish appetite, whole body composition, hepatic glycogen and lipid contents, intestinal bacterial and Aeromonas counts, as well as hepatic tumor necrosis factor- α (TNF-α). In addition, the mRNA expression of genes related to gluconeogenesis (pck1, gys2, and g6pc3), lipogenesis (srepf1, acaca, fasn, and cd36), and inflammatory response (tnf-α, tnf-β, nf-kb2) were modulated. D. salina reduced the body burden of zinc residues, restored the fish appetite and normal liver architecture, and mitigated the toxic impacts of ZnO-NPs on whole-body composition, intestinal bacteria, energy metabolism, and hepatic inflammatory markers. Our results revealed that the administration of D. salina might be effective in neutralizing the hepatotoxic effects of ZnO-NPs in the zebrafish model.

Milk Exosomal microRNAs: Postnatal Promoters of β Cell Proliferation but Potential Inducers of β Cell De-Differentiation in Adult Life

Pancreatic β cell expansion and functional maturation during the birth-to-weaning period is driven by epigenetic programs primarily triggered by growth factors, hormones, and nutrients provided by human milk. As shown recently, exosomes derived from various origins interact with β cells. This review elucidates the potential role of milk-derived exosomes (MEX) and their microRNAs (miRs) on pancreatic β cell programming during the postnatal period of lactation as well as during continuous cow milk exposure of adult humans to bovine MEX. Mechanistic evidence suggests that MEX miRs stimulate mTORC1/c-MYC-dependent postnatal β cell proliferation and glycolysis, but attenuate β cell differentiation, mitochondrial function, and insulin synthesis and secretion. MEX miR content is negatively affected by maternal obesity, gestational diabetes, psychological stress, caesarean delivery, and is completely absent in infant formula. Weaning-related disappearance of MEX miRs may be the critical event switching β cells from proliferation to TGF-β/AMPK-mediated cell differentiation, whereas continued exposure of adult humans to bovine MEX miRs via intake of pasteurized cow milk may reverse β cell differentiation, promoting β cell de-differentiation. Whereas MEX miR signaling supports postnatal β cell proliferation (diabetes prevention), persistent bovine MEX exposure after the lactation period may de-differentiate β cells back to the postnatal phenotype (diabetes induction).

Possible role of transcription factors (BSX, NKX2.1, IRX3 and SIRT1) in the regulation of appetite in goldfish (Carassius auratus)

The homeobox genes play important roles in the embryonic development of animals. Recent evidence suggests they might also regulate feeding and act as transcription factors of appetite regulators. Examples of these genes are a brain-specific homeobox transcription factor (BSX), NK2 homeobox 1 (NKX2.1) and the Iroquois homeobox 3 (IRX3). Sirtuin1 (SIRT1) acts as a transcription factor for nutrient (e.g. lipid, glucose) homeostasis and responds to stress and nutrient availability, and has been shown to interact with appetite regulators. Very little is known about the role of these genes in the regulation of feeding and nutrient homeostasis in fish. In this study, we assessed the roles of BSX, NKX2.1, IRX3 and SIRT1 in the central regulation of feeding in goldfish by examining their mRNA brain distribution, assessing the effects of fasting on their brain expression and assessing the effects of peripheral injections of cholecystokinin (CCK, a brain-gut peptide), on their brain expression. All genes showed a widespread distribution in the brain, with high levels in the hypothalamus. In both hypothalamus and telencephalon, fasting induced increases in BSX, IRX3 and NKX2.1 expressions but had no effect on SIRT1 expression levels. CCK injections increased hypothalamic expression levels of IRX3 and SIRT1, and telencephalic expression levels of NKX2.1 and SIRT1, with no effect on either hypothalamic BSX or NKX2.1 expression levels or telencephalon BSX or IRX3 expression levels. Our results suggest that, in goldfish as in mammals, central BSX, NKX2.1, IRX3 and SIRT1 are present in regions of the brain regulating feeding, are sensitive to nutrient status and interact with appetite-regulating peptides.

The regulatory role of N6 -methyladenosine modification in the interaction between host and microbes

N⁶ -methyladenosine (m⁶ A) is the most prevalent posttranscriptional modification in eukaryotic mRNAs. Dynamic and reversible m⁶ A modification regulates gene expression to control cellular processes and diverse biological functions. Growing evidence indicated that m⁶ A modification is involved in the homeostasis of host and microbes (mostly viruses and bacteria). Disturbance of m⁶ A modification affects the life cycles of viruses and bacteria, however, these microbes could in turn change host m⁶ A modification leading to human disease including autoimmune diseases and cancer. Thus, we raise the concept that m⁶ A could be a "messenger" molecule to participate in the interactions between host and microbes. In this review, we summarize the regulatory mechanisms of m⁶ A modification on viruses and commensal microbiota, highlight the roles of m⁶ A methylation in the interaction of host and microbes, and finally discuss drugs development targeting m⁶ A modification. This article is categorized under: RNA in Disease and Development > RNA in Disease.

The role of RNA m6A methylation in lipid metabolism

The m6A methylation is the most numerous modification of mRNA in mammals, coordinated by RNA m6A methyltransferases, RNA m6A demethylases, and RNA m6A binding proteins. They change the RNA m6A methylation level in their specific manner. RNA m6A modification has a significant impact on lipid metabolic regulation. The "writer" METTL3/METTL14 and the "eraser" FTO can promote the accumulation of lipids in various cells by affecting the decomposition and synthesis of lipids. The "reader" YTHDF recognizes m6A methylation sites of RNA and regulates the target genes' translation. Due to this function that regulates lipid metabolism, RNA m6A methylation plays a pivotal role in metabolic diseases and makes it a great potential target for therapy.

Environmentally relevant concentrations of tralopyril affect carbohydrate metabolism and lipid metabolism of zebrafish (Danio rerio) by disrupting mitochondrial function

Tralopyril (TP), an antifouling biocide, is widely used to prevent heavy biofouling, and can have potential risks to aquatic organisms. However, there is little information available on the toxicity of tralopyril to aquatic organisms. In this study, the effect of TP on carbohydrate and lipid metabolism, and related mechanisms were evaluated in zebrafish (Danio rerio) larvae. Adverse modifications in carbohydrate metabolism were observed in larvae: hexokinase (HK) activity, succinate dehydrogenase (SDH) activity, and adenosine triphosphate (ATP) content were significantly decreased; and transcript expression of genes (GK, HK1, and PCK1) was also significantly changed. Changes of TG content, FAS activity and transcript expression of genes (ACO, ehhadh, and fas) indicate that TP disrupt lipid metabolism in zebrafish larvae. The change in expression of genes (ndufs4, Sdhα, and uqcrc2) involved in the mitochondrial respiratory complexes, and genes (polg1 and tk2) involved in the mitochondrial DNA replication and transcription indicates that these adverse effects on carbohydrate and lipid metabolism are caused by mitochondrial dysfunction.

Comprehensive analysis of N6-methyladenosine -related long non-coding RNAs and immune cell infiltration in hepatocellular carcinoma

We aimed to illustrate the influence of N6-methyladenosine (m6A) long non-coding RNAs (lncRNAs) and immune cell infiltration in hepatocellular carcinoma (HCC). The relationship of lncRNAs and m6A was identified through gene expression analysis using PERL and R packages. The Kyoto Encyclopedia of Genes and Genomes gene expression enrichment analysis was performed via gene set enrichment analysis. Lasso regression was utilized to construct prognostic model. Differences in the tumor microenvironment and the immune correlation were analyzed to clarify immune cell infiltration in different clusters and their correlation with the clinical prognosis. Co-expression analysis showed that lncRNA expression was associated closely with m6A. Many lncRNAs were predictive risk factors of prognosis in HCC. m6A-lncRNAs were partially highly expressed in tumor tissue and could be used in a prognostic model to predict HCC prognosis, independent of other clinical characteristics. ‘NOTCH SIGNALING PATHWAY’ was most significantly enriched according to GSEA. CKLF-like MARVEL transmembrane domain-containing member 3 (CMTM3) was overexpressed in tumor tissue. Immune cells, such as activated CD4 memory T cells, CD8 T cells, and follicular helper T cells, highly infiltrated tissues in cluster 2. All related scores were higher in cluster 2, indicating a lower purity of tumor cells and higher density of immune-related cells in the tumor microenvironment. m6A-lncRNAs are closely related to HCC occurrence and progression. Corresponding prognostic models can help predict HCC prognosis. m6A-lncRNAs and the related immune cell infiltration in the tumor microenvironment can provide novel therapeutic targets in HCC that need to be further studied.