METTL14/YTHDF1 axis-modified UCHL5 aggravates atherosclerosis by activating the NLRP3 inflammasome

Updated insights into the molecular networks for NLRP3 inflammasome activation

Over the past decade, significant advances have been made in our understanding of how NACHT-, leucine-rich-repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasomes are activated. These findings provide detailed insights into the transcriptional and posttranslational regulatory processes, the structural-functional relationship of the activation processes, and the spatiotemporal dynamics of NLRP3 activation. Notably, the multifaceted mechanisms underlying the licensing of NLRP3 inflammasome activation constitute a focal point of intense research. Extensive research has revealed the interactions of NLRP3 and its inflammasome components with partner molecules in terms of positive and negative regulation. In this Review, we provide the current understanding of the complex molecular networks that play pivotal roles in regulating NLRP3 inflammasome priming, licensing and assembly. In addition, we highlight the intricate and interconnected mechanisms involved in the activation of the NLRP3 inflammasome and the associated regulatory pathways. Furthermore, we discuss recent advances in the development of therapeutic strategies targeting the NLRP3 inflammasome to identify potential therapeutics for NLRP3-associated inflammatory diseases. As research continues to uncover the intricacies of the molecular networks governing NLRP3 activation, novel approaches for therapeutic interventions against NLRP3-related pathologies are emerging.

Mechanisms and therapeutic strategies for NLRP3 degradation via post-translational modifications in ubiquitin-proteasome and autophagy lysosomal pathway

The NLRP3 inflammasome is crucial for immune responses. However, its overactivation can lead to severe inflammatory diseases, underscoring its importance as a target for therapeutic intervention. Although numerous inhibitors targeting NLRP3 exist, regulating its degradation offers an alternative and promising strategy to suppress its activation. The degradation of NLRP3 is primarily mediated by the proteasomal and autophagic pathways. The review not only elaborates on the traditional concepts of ubiquitination and NLRP3 degradation but also investigates the important roles of indirect regulatory modifications, such as phosphorylation, acetylation, ubiquitin-like modifications, and palmitoylation-key post-translational modifications (PTMs) that influence NLRP3 degradation. Additionally, we also discuss the potential targets that may affect NLRP3 degradation during the proteasomal and autophagic pathways. By unraveling these complex regulatory mechanisms, the review aims to enhance the understanding of NLRP3 regulation and its implications for developing therapeutic strategies to combat inflammatory diseases.

Heat stress enhances the expression of METTL3 to mediate N6-methyladenosine modification of SOS2 and NLRP3 inflammasome activation in boar Sertoli cells

Heat stress negatively affects pig production by disrupting the immune homeostasis of Sertoli cells (SCs), which compromises sperm quality, culminating in male infertility. Herein, we aimed to study the mechanism by which the NLRP3 inflammasome is activated by heat stress through N6-methyladenosine (m6A) modification regulation in SCs. Initially, it was found that heat stress (44°C, 30 min) markedly activated ERK1/2 signaling, which subsequently promoted NLRP3 inflammasome activation and inflammatory cytokine release from SCs. Then, using an m6A dot-blot assay, m6A sequencing, and methylated RNA immunoprecipitation, we found that heat stress augmented the level of m6A modification in SCs, and METTL3 augmented the m6A modification of mRNA encoding SOS Ras/Rho guanine nucleotide exchange factor 2 (SOS2), a key activator of the ERK pathway. Furthermore, YTHDF1 recognized and bound to the m6A-modified SOS2 mRNA to enhance its translation efficiency, ultimately triggering ERK1/2 signaling activation. In vivo experiments demonstrated that heat stress-induced decline in semen quality in mice was associated with elevated levels of m6A modifications in the testis and NLRP3 inflammasome activation. However, the damage caused by heat stress could be attenuated by intraperitoneal injection of S-Adenosylhomocysteine (SAH), a specific methyltransferase inhibitor. Our results emphasize the critical roles of m6A in regulating NLRP3 inflammasome activation under heat stress, identifying a novel therapeutic avenue to address heat stress.

The N6-methyladenosine demethylase ALKBH5 is a novel epigenetic regulator of aortic valve calcification

AIMS

Calcific aortic valve disease (CAVD) is a common heart valve disease with significant clinical consequences. The mechanisms that drive the pathogenesis of CAVD remain to be fully elucidated. N6-methyladenosine (m6A), the most prevalent RNA epigenetic regulator, has recently been implicated in cardiovascular disease, but its role in CAVD has yet to be investigated. In this study, we investigated the potential function of m6A modification in CAVD.

METHODS AND RESULTS

Using clinical samples from CAVD patients in combination with human valve interstitial cell (hVIC) calcification model, we screened the expression of m6A modulators and discovered that alkB homolog 5, RNA demethylase (ALKBH5), a key m6A demethylase, was significantly down-regulated in calcified hVICs and human aortic valves. Consistently, increased m6A levels were seen in calcified hVICs, and treatment with 3-deazaadenosine (DAA), an inhibitor of m6A modification, significantly reduced hVIC osteogenic differentiation and calcification. In addition, we showed that silencing of ALKBH5 expression increased global m6A levels and accelerated hVIC osteogenic differentiation and calcification, whereas overexpression of ALKBH5 resulted in the opposite effect. We demonstrated that ALKBH5 directly modulate m6A levels of TGFBR2 and its mRNA stability, leading to altered TGFBR2 expression and SMAD2 signalling in hVICs. We further showed that inhibition of TGFBR2 or knockdown of SMAD2 attenuated ALKBH5 knockdown-induced hVIC osteogenic differentiation and calcification. The expression of the m6A reader protein YTH N6-methyladenosine RNA binding protein F1 (YTHDF1) was up-regulated during the process of hVIC calcification. Intriguingly, we revealed that the ALKBH5 silencing-induced increased hVIC osteogenic differentiation and calcification were abolished after knockdown of YTHDF1. These data suggest a potential role YTHDF1 in aortic valve calcification.

CONCLUSION

This study showed that ALKBH5 attenuated aortic valve calcification through the TGFBR2/SMAD2 signalling pathway via direct m6A modification of TGFBR2.

Epitranscriptomics in atherosclerosis: Unraveling RNA modifications, editing and splicing and their implications in vascular disease

Atherosclerosis remains a leading cause of morbidity and mortality worldwide, driven by complex molecular mechanisms involving gene regulation and post-transcriptional processes. Emerging evidence highlights the critical role of epitranscriptomics, the study of chemical modifications occurring on RNA molecules, in atherosclerosis development. Epitranscriptomics provides a new layer of regulation in vascular health, influencing cellular functions in endothelial cells, smooth muscle cells, and macrophages, thereby shedding light on the pathogenesis of atherosclerosis and presenting new opportunities for novel therapeutic targets. This review provides a comprehensive overview of the epitranscriptomic landscape, focusing on key RNA modifications such as N6-methyladenosine (m6A), 5-methylcytosine (m5C), pseudouridine (Ψ), RNA editing mechanisms including A-to-I and C-to-U editing and RNA isoforms. The functional implications of these modifications in RNA stability, alternative splicing, and microRNA biology are discussed, with a focus on their roles in inflammatory signaling, lipid metabolism, and vascular cell adaptation within atherosclerotic plaques. We also highlight how these modifications influence the generation of RNA isoforms, potentially altering cellular phenotypes and contributing to disease progression. Despite the promise of epitranscriptomics, significant challenges remain, including the technical limitations in detecting RNA modifications in complex tissues and the need for deeper mechanistic insights into their causal roles in atherosclerotic pathogenesis. Integrating epitranscriptomics with other omics approaches, such as genomics, proteomics, and metabolomics, holds the potential to provide a more holistic understanding of the disease.

Mechanism of Si Ni San Combined with Astragalus in Treating Hepatic Fibrosis: A Network Pharmacology and Molecular Docking Study

Si Ni San combined with Astragalus (SNSQ) has demonstrated significant efficacy in the treatment of hepatic fibrosis (HF), as confirmed by clinical practice. However, its pharmacological mechanism remains unclear. This study employs network pharmacology to identify key targets and proteins for molecular docking. Additionally, animal experiments were conducted to validate the network pharmacology results, providing further insights into the mechanism of SNSQ in treating HF. Effective compounds of SNSQ were screened from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) and Encyclopedia of Traditional Chinese Medicine (ETCM) databases. Molecular formula structures of these effective compounds were obtained from the PubChem database. Partial target proteins with a probability greater than 0.6 were sourced from the SWISS database. Uniprot IDs corresponding to these target proteins were retrieved from the SUPERPRED database. The remaining target proteins of the compounds were obtained from the Uniprot database based on the Uniprot IDs. The drug target proteins were then summarized. Target points related to HF were selected from the GeneCards and OMIM databases. Common target points were identified in the Venn diagram and imported into Cytoscape 3.9.1 software to construct the "SNSQ-effective compound-target pathway-HF" network. AutoDock software was used for molecular docking of compounds and target proteins with high-degree values. The common target points underwent GO function enrichment and KEGG pathway enrichment analysis using the DAVID database. An HF rat model was established, and serum AST and ALT activities were measured. The Hyp assay kit was utilized to detect the Hyp content in liver tissue. To the transcription levels of pro-inflammatory factors (IL-1β, TNF-α, IL-6) and anti-inflammatory factors (IL-10, TGF-β1, IL-4) in rat serum and liver.IL-1β, TNF-α, IL-10, and TGF-β1 were chosen for validation through ELISA. Western blotting and qRT-PCR were used to assess the expression of related proteins, namely NFKB1, NF-κBp65, NF-κBp50, α-SMA, and Col-1 in liver tissue. qRT-PCR was also employed to study the expression of ECM synthesis and proliferation-related genes, including Cyclin D1, TIMP1, COL1A1 in HSC-T6 cells and rat liver tissue, as well as the inhibition of the ECM-related gene MMP13 in HSC-T6 cells and rat liver tissue. A total of 16 valid compounds were predicted, with kaempferol, sitosterol, and isorhamnetin exhibiting high-degree values. KEGG enrichment analysis revealed that the target genes of SNSQ were enriched in multiple pathological pathways, with the NF-Kappa B signaling pathway being predominant. Molecular docking simulations indicated strong affinities between SNSQ's primary components-kaempferol, sitosterol, isorhamnetin-and NFKB1. Experimental results demonstrated significant reductions in AST, ALT, and Hyp levels in the SNSQ group. Pro-inflammatory factors (IL-1β, TNF-ɑ) were markedly reduced, while anti-inflammatory factors (IL-10, TGF-β1) were substantially increased. The protein expression and transcription levels of α-SMA and Col-1 were significantly decreased, whereas those of NFKB1, NF-κBp65, and NF-κBp50 were notably elevated. mRNA expression levels of Cyclin D1, TIMP1, COL1A1 in HSC-T6 cells and rat liver tissue were significantly decreased, whereas MMP13 mRNA expression level was significantly increased. Treatment of HF with SNSQ involves multiple targets and pathways, with a close association with the overexpression of NFKB1 and activation of the NF-Kappa B signaling pathway. Its mechanism is closely linked to the activation of inflammatory responses, HSC activation, and proliferation.

Recent Advances in the Mutual Regulation of m6A Modification and Non-Coding RNAs in Atherosclerosis

Atherosclerosis, a progressive inflammatory disease of the arteries, remains a leading cause of cardiovascular morbidity and mortality worldwide. Recent years have witnessed the pivotal role of N6-methyladenosine (m6A) RNA methylation in regulating various biological processes, including those implicated in atherosclerosis. Current evidence suggested that m6A regulators (writers, erasers, and readers) participated in the modification of multiple non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), thereby affecting their metabolism and functions. Meanwhile, ncRNAs have also emerged as key modulator of m6A regulators expression in turn. Therefore, understanding the mutual regulation between m6A modifications and ncRNAs is of great significance to identify novel therapeutic targets for atherosclerosis and has great clinical application prospects. This review aims to summarize the recent advances in the reciprocal regulation and provide insights into the interaction between m6A modification and ncRNAs in the context of atherosclerosis.

N6-methyladenosine in inflammatory diseases: Important actors and regulatory targets

N6-methyladenosine (m6A) is one of the most prevalent epigenetic modifications in eukaryotic cells. It regulates RNA function and stability by modifying RNA methylation through writers, erasers, and readers. As a result, m6A plays a critical role in a wide range of biological processes. Inflammation is a common and fundamental pathological process. Numerous studies have investigated the role of m6A modifications in inflammatory diseases. This review highlights the mechanisms by which m6A contributes to inflammation, focusing on pathogen-induced infectious diseases, autoimmune disorders, allergic conditions, and metabolic disorder-related inflammatory diseases.

METTL14 promotes ferroptosis in smooth muscle cells during thoracic aortic aneurysm by stabilizing the m6A modification of ACSL4

Thoracic aortic aneurysm (TAA) is a vascular disease associated with high mortality rates. Ferroptosis has been shown to mediate the transformation of vascular smooth muscle cells (VSMCs). However, the regulatory mechanisms by which ferroptosis influences TAA remain unclear. In this study, we induced TAA mouse models using angiotensin II (Ang II) and evaluated the impact of ferroptosis on the pathological changes observed in TAA mice, employing liproxstatin-1 as a treatment. In addition, we assessed the regulatory effect of METTL14 on the ferroptosis of VSMCs after treating them with a ferroptosis activator (imidazole ketone erastin, IKE). RNA binding protein immunoprecipitation (RIP) and RNA pull-down assays were conducted to investigate the interaction between acyl-CoA synthase long-chain family member 4 (ACSL4) mRNA and the proteins METTL14 or IGF2BP2. The results indicated that the level of ferroptosis was elevated in the thoracic aorta of TAA mice, and METTL14 was upregulated in TAA models and IKE-induced VSMCs. Knockdown of METTL14 was found to inhibit the progression of TAA by reducing the ferroptosis of VSMCs. Furthermore, IGF2BP2 recognized METTL14-modified ACSL4 mRNA and regulated its stability, thereby mediating the ferroptosis of VSMCs. Collectively, the effects of METTL14 on VSMC ferroptosis present therapeutic potential for the treatment of TAA.NEW & NOTEWORTHY Our study confirmed that METTL14 can induce ferroptosis in vascular smooth muscle cells during the progression of thoracic aortic aneurysm by mediating the m6A modification of ACSL4 mRNA.

Unraveling the priming phase of NLRP3 inflammasome activation: Molecular insights and clinical relevance

The NLRP3 inflammasome plays a pivotal role in the innate immune response. Its activation involves a two-step mechanism that consists of priming and activation. The priming of the NLRP3 inflammasome is a vital initial phase necessary for its activation and subsequent involvement in the immune response, though its understanding varies across studies. Recent research has identified key proteins that influence the priming process, revealing a sophisticated regulatory network. This review provides a comprehensive review of the priming phase of NLRP3 inflammasome activation, with a particular focus on the underlying molecular mechanisms, including transcriptional regulation, orchestration of the phosphorylation status, deubiquitination and the relationships with the inflammation-associated diseases. Understanding the intricacies of NLRP3 inflammasome priming not only elucidates fundamental aspects of immune regulation, but also provides potential avenues for therapeutic intervention in inflammatory diseases.

WTAP participates in neuronal damage by protein translation of NLRP3 in an m6A-YTHDF1-dependent manner after traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a common complication of acute and severe neurosurgery. Remodeling of N6-methyladenosine (m6A) stabilization may be an attractive treatment option for neurological dysfunction after TBI. In the present study, the authors explored the epigenetic methylation of RNA-mediated NLRP3 inflammasome activation after TBI.

METHODS

Neurological dysfunction, histopathology, and associated molecules were examined in conditional knockout (CKO) WTAP [flox/flox, Camk2a-cre] , WTAP flox/flox , and pAAV-U6-shRNA-YTHDF1-transfected mice. Primary neurons were used in vitro to further explore the molecular mechanisms of action of WTAP/YTHDF1 following neural damage.

RESULTS

The authors found that WTAP and m6A levels were upregulated at an early stage after TBI, and conditional deletion of WTAP in neurons did not affect neurological function but promoted functional recovery after TBI. Conditional deletion of WTAP in neurons suppressed neuroinflammation at the TBI early phase: WTAP could directly act on NLRP3 mRNA, regulate NLRP3 mRNA m6A level, and promote NLRP3 expression after neuronal injury. Further investigation found that YTH domain of YTHDF1 could directly bind to NLRP3 mRNA and regulate NLRP3 protein expression. YTHDF1 mutation or silencing improved neuronal injury, inhibited Caspase-1 activation, and decreased IL-1β levels. This effect was mediated via suppression of NLRP3 protein translation, which also reversed the stimulative effect of WTAP overexpression on NLRP3 expression and inflammation.

CONCLUSIONS

Our results indicate that WTAP participates in neuronal damage by protein translation of NLRP3 in an m6A-YTHDF1-dependent manner after TBI and that WTAP/m6A/YTHDF1 downregulation therapeutics is a viable and promising approach for preserving neuronal function after TBI, which can provide support for targeted drug development.

N6-Methyladenosine in Vascular Aging and Related Diseases: Clinical Perspectives

Aging leads to progressive deterioration of the structure and function of arteries, which eventually contributes to the development of vascular aging-related diseases. N6-methyladenosine (m6A) is the most prevalent modification in eukaryotic RNAs. This reversible m6A RNA modification is dynamically regulated by writers, erasers, and readers, playing a critical role in various physiological and pathological conditions by affecting almost all stages of the RNA life cycle. Recent studies have highlighted the involvement of m6A in vascular aging and related diseases, shedding light on its potential clinical significance. In this paper, we comprehensively discuss the current understanding of m6A in vascular aging and its clinical implications. We discuss the molecular insights into m6A and its association with clinical realities, emphasizing its significance in unraveling the mechanisms underlying vascular aging. Furthermore, we explore the possibility of m6A and its regulators as clinical indicators for early diagnosis and prognosis prediction and investigate the therapeutic potential of m6A-associated anti-aging approaches. We also examine the challenges and future directions in this field and highlight the necessity of integrating m6A knowledge into patient-centered care. Finally, we emphasize the need for multidisciplinary collaboration to advance the field of m6A research and its clinical application.

m6A epitranscriptomic modification of inflammation in cardiovascular disease

Cardiovascular disease is currently the number one cause of death endangering human health. There is currently a large body of research showing that the development of cardiovascular disease and its complications is often accompanied by inflammatory processes. In recent years, epitranscriptional modifications have been shown to be involved in regulating the pathophysiological development of inflammation in cardiovascular diseases, with 6-methyladenine being one of the most common RNA transcriptional modifications. In this review, we link different cardiovascular diseases, including atherosclerosis, heart failure, myocardial infarction, and myocardial ischemia-reperfusion, with inflammation and describe the regulatory processes involved in RNA methylation. Advances in RNA methylation research have revealed the close relationship between the regulation of transcriptome modifications and inflammation in cardiovascular diseases and brought potential therapeutic targets for disease diagnosis and treatment. At the same time, we also discussed different cell aspects. In addition, in the article we also describe the different application aspects and clinical pathways of RNA methylation therapy. In summary, this article reviews the mechanism, regulation and disease treatment effects of m6A modification on inflammation and inflammatory cells in cardiovascular diseases in recent years. We will discuss issues facing the field and new opportunities that may be the focus of future research.

N6-methyladenosine methylation on FSCN1 mediated by METTL14/IGF2BP3 contributes to human papillomavirus type 16-infected cervical squamous cell carcinoma

Human papillomavirus (HPV) infection has been reported to be associated with N6-methyladenosine (m6A) modification in cancers. However, the underlying mechanism by which m6A methylation participates in HPV-related cervical squamous cell carcinoma (CSCC) remains largely unclear. In this study, we observed that m6A regulators methyltransferase like protein (METTL14) and insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3) were upregulated in HPV-positive CSCC tissues and cell lines, and their high expression predicted poor prognosis for HPV-infected CSCC patients. Cellular functional experiments verified that HPV16 oncogenes E6/E7 upregulated the expression of METTL14 and IGF2BP3 to promote cell proliferation and epithelial mesenchymal transition of CSCC cells. Next, we found that E6/E7 stabilized fascin actin-bundling protein 1 (FSCN1) mRNA and elevated FSCN1 expression in CSCC cells through upregulating METTL14/IGF2BP3-mediated m6A modification, and FSCN1 expression was also validated to be positively associated with worse outcomes of HPV-positive CSCC patients. Finally, HPV16-positive CSCC cell lines SiHa and CaSki were transfected with knockdown vector for E6/E7 or METTL14/IGF2BP3 and overexpressing vector for FSCN1, and functional verification experiments were performed through using MTT assay, flow cytometry, wound healing assay and tumour formation assay. Results indicated that knockdown of E6/E7 or METTL14/IGF2BP3 suppressed cell proliferation, migration and tumorigenesis, and accelerated cell apoptosis of HPV-positive CSCC cells. Their tumour-suppressive effects were abolished through overexpressing FSCN1. Overall, HPV E6/E7 advanced CSCC development through upregulating METTL14/IGF2BP3-mediated FSCN1 m6A modification.

Levels and clinical significance of the m6A methyltransferase METTL14 in patients with coronary heart disease

Objective

To investigate the association of methyltransferase-like protein 14 (METTL14) expression with coronary heart disease (CHD).

Methods

Three hundred and sixteen patients who attended Henan Provincial People's Hospital between June 2019 and February 2021 with principal symptoms of pain or tightness in the chest and who underwent coronary angiography for definitive diagnosis were enrolled. The uric acid, TG, TC, LDL-C, HDL-C, apolipoprotein A1, free fatty acid, lipoprotein a, homocysteine, CRP, and SAA levels were examined. The levels of METTL14, TNF-α, MCP-1, VCAM-1, ICAM-1, and IL-6 were evaluated by ELISA.

Results

Patients with CHD had significantly higher m6A methyltransferase activity. In addition, the incidence of diabetes and hypertension, as well as the concentrations of TC, CRP, and SAA were higher in CHD patients. Patients with coronary lesion branches also had significantly increased TG, LDL-C, CRP, and SAA levels. TNF-α, MCP-1, VCAM-1, ICAM-1, and IL-6 expression was also markedly increased in the CHD group (P < 0.001) as was the expression of METTL14 (P < 0.001). The METTL14 expression levels also differed significantly in relation to the number of branches with lesions (P < 0.01) and were correlated with SAA, VCAM-1, ICAM-1, IL-6, and the Gensini score. ROC curve analyses of METTL14 in CHD indicated an AUC of 0.881 (0.679, 0.894) with a cut-off value of 342.37, a sensitivity of 77%, and a specificity of 84%. MCP-1, VCAM-1, IL-6, SAA, and METTL14 were found to independently predict CHD risk.

Conclusions

METTL14 levels were found to be positively associated with inflammatory markers and to be an independent predictor of CHD risk.