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

Insight into the regulatory mechanism of m6A modification: From MAFLD to hepatocellular carcinoma

In recent years, there has been a significant increase in the incidence of metabolic-associated fatty liver disease (MAFLD), which has been attributed to the increasing prevalence of type 2 diabetes mellitus (T2DM) and obesity. MAFLD affects more than one-third of adults worldwide, making it the most prevalent liver disease globally. Moreover, MAFLD is considered a significant risk factor for hepatocellular carcinoma (HCC), with MAFLD-related HCC cases increasing. Approximately 1 in 6 HCC patients are believed to have MAFLD, and nearly 40 % of these HCC patients do not progress to cirrhosis, indicating direct transformation from MAFLD to HCC. N6-methyladenosine (m6A) is commonly distributed in eukaryotic mRNA and plays a crucial role in normal development and disease progression, particularly in tumors. Numerous studies have highlighted the close association between abnormal m6A modification and cellular metabolic alterations, underscoring its importance in the onset and progression of MAFLD. However, the specific impact of m6A modification on the progression of MAFLD to HCC remains unclear. Can targeting m6A effectively halt the progression of MAFLD-related HCC? In this review, we investigated the pivotal role of abnormal m6A modification in the transition from MAFLD to HCC, explored the potential of m6A modification as a therapeutic target for MAFLD-related HCC, and proposed possible directions for future investigations.

Gender-specific effects of polystyrene nanoplastic exposure on triclosan-induced reproductive toxicity in zebrafish (Danio rerio)

Nanoplastics (NPs) and triclosan (TCS) are ubiquitous emerging environmental contaminants detected in human samples. While the reproductive toxicity of TCS alone has been studied, its combined effects with NPs remain unclear. Herein, we employed Fourier transform infrared spectroscopy and dynamic light scattering to characterize the coexposure of polystyrene nanoplastics (PS-NPs, 50 nm) with TCS. Then, adult zebrafish were exposed to TCS at environmentally relevant concentrations (0.361-48.2 μg/L), with or without PS-NPs (1.0 mg/L) for 21 days. TCS biodistribution in zebrafish tissues was investigated using ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry. Reproductive toxicity was assessed through gonadal histopathology, fertility tests, changes in steroid hormone synthesis and gene expression within the hypothalamus-pituitary-gonad-liver (HPGL) axis. Transcriptomics and proteomics were applied to explore the underlying mechanisms. The results showed that PS-NPs could adsorb TCS, thus altering the PS-NPs' physical characteristics. Our observations revealed that coexposure with PS-NPs reduced TCS levels in the ovaries, livers, and brains of female zebrafish. Conversely, in males, coexposure with PS-NPs increased TCS levels in the testes and livers, while decreasing them in the brain. We found that co-exposure mitigated TCS-induced ovary development inhibition while exacerbated TCS-induced spermatogenesis suppression, resulting in increased embryonic mortality and larval malformations. This co-exposure influenced the expression of genes linked to steroid hormone synthesis (cyp11a1, hsd17β, cyp19a1) and attenuated the TCS-decreased estradiol (E2) in females. Conversely, testosterone levels were suppressed, and E2 levels were elevated due to the upregulation of specific genes (cyp11a1, hsd3β, cyp19a1) in males. Finally, the integrated analysis of transcriptomics and proteomics suggested that the aqp12-dctn2 pathway was involved in PS-NPs' attenuation of TCS-induced reproductive toxicity in females, while the pck2-katnal1 pathway played a role in PS-NPs' exacerbation of TCS-induced reproductive toxicity in males. Collectively, PS-NPs altered TCS-induced reproductive toxicity by disrupting the HPGL axis, with gender-specific effects.

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.

RNA methylation-related inhibitors: Biological basis and therapeutic potential for cancer therapy

RNA methylation is widespread in nature. Abnormal expression of proteins associated with RNA methylation is strongly associated with a number of human diseases including cancer. Increasing evidence suggests that targeting RNA methylation holds promise for cancer treatment. This review specifically describes several common RNA modifications, such as the relatively well-studied N6-methyladenosine, as well as 5-methylcytosine and pseudouridine (Ψ). The regulatory factors involved in these modifications and their roles in RNA are also comprehensively discussed. We summarise the diverse regulatory functions of these modifications across different types of RNAs. Furthermore, we elucidate the structural characteristics of these modifications along with the development of specific inhibitors targeting them. Additionally, recent advancements in small molecule inhibitors targeting RNA modifications are presented to underscore their immense potential and clinical significance in enhancing therapeutic efficacy against cancer. KEY POINTS: In this paper, several important types of RNA modifications and their related regulatory factors are systematically summarised. Several regulatory factors related to RNA modification types were associated with cancer progression, and their relationships with cancer cell migration, invasion, drug resistance and immune environment were summarised. In this paper, the inhibitors targeting different regulators that have been proposed in recent studies are summarised in detail, which is of great significance for the development of RNA modification regulators and cancer treatment in the future.

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.

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.