Integrative analysis implicates the significance of m6A in the liver fibrosis of biliary atresia by regulating THY1

Regulatory roles of N6-methyladenosine (m6A) methylation in RNA processing and non-communicable diseases

Post-transcriptional RNA modification is an emerging epigenetic control mechanism in cells that is important in many different cellular and organismal processes. N6-methyladenosine (m6A) is one of the most prevalent, prolific, and ubiquitous internal transcriptional alterations in eukaryotic mRNAs, making it an important topic in the field of Epigenetics. m6A methylation acts as a dynamical regulatory process that regulates the activity of genes and participates in multiple physiological processes, by supporting multiple aspects of essential mRNA metabolic processes, including pre-mRNA splicing, nuclear export, translation, miRNA synthesis, and stability. Extensive research has linked aberrations in m6A modification and m6A-associated proteins to a wide range of human diseases. However, the impact of m6A on mRNA metabolism and its pathological connection between m6A and other non-communicable diseases, including cardiovascular disease, neurodegenerative disorders, liver diseases, and cancer remains in fragmentation. Here, we review the existing understanding of the overall role of mechanisms by which m6A exerts its activities and address new discoveries that highlight m6A's diverse involvement in gene expression regulation. We discuss m6A deposition on mRNA and its consequences on degradation, translation, and transcription, as well as m6A methylation of non-coding chromosomal-associated RNA species. This study could give new information about the molecular process, early detection, tailored treatment, and predictive evaluation of human non-communicable diseases like cancer. We also explore more about new data that suggests targeting m6A regulators in diseases may have therapeutic advantages.

Integrins in biliary injury and fibrosis

PURPOSE OF REVIEW

Current treatment options for cholangiopathies are severely limited and there is thus a critical need to identify and develop therapies. This review discusses the role of integrins in biliary injury and fibrosis and their potential as therapeutic targets.

RECENT FINDINGS

There are a diverse set of roles that integrins play in biliary injury and fibrosis. Some integrins activate TGF-β signaling or are involved in sensing of the extracellular matrix, making them attractive targets for biliary fibrosis. In recent work, autoantibodies to α v β 6 were identified in patients with PSC, supporting the relevance of this integrin in the disease. In addition, a role for α 2 β 1 in cyst formation was identified in a mouse model of polycystic liver disease. Leukocyte integrins (e.g. α E β 7 and α 4 β 7 ) contribute to lymphocyte trafficking, making them potential targets for biliary inflammation; however, this has not yet translated to the clinic.

SUMMARY

While all members of the same family of proteins, integrins have diverse roles in the pathogenesis of biliary disease. Targeting one or multiple of these integrins may slow or halt the progression of biliary injury and fibrosis by simultaneously impacting different pathologic cells and processes.

Emerging role of m6A modification in fibrotic diseases and its potential therapeutic effect

Fibrosis can occur in a variety of organs such as the heart, lung, liver and kidney, and its pathological changes are mainly manifested by an increase in fibrous connective tissue and a decrease in parenchymal cells in organ tissues, and continuous progression can lead to structural damage and organ hypofunction, or even failure, seriously threatening human health and life. N6-methyladenosine (m6A) modification, as one of the most common types of internal modifications of RNA in eukaryotes, exerts a multifunctional role in physiological and pathological processes by regulating the metabolism of RNA. With the in-depth understanding and research of fibrosis, we found that m6A modification plays an important role in fibrosis, and m6A regulators can further participate in the pathophysiological process of fibrosis by regulating the function of specific cells. In our review, we summarized the latest research advances in m6A modification in fibrosis, as well as the specific functions of different m6A regulators. In addition, we focused on the mechanisms and roles of m6A modification in cardiac fibrosis, liver fibrosis, pulmonary fibrosis, renal fibrosis, retinal fibrosis and oral submucosal fibrosis, with the aim of providing new insights and references for finding potential therapeutic targets for fibrosis. Finally, we discussed the prospects and challenges of targeted m6A modification in the treatment of fibrotic diseases.

METTL3-mediated m6A RNA methylation induces the differentiation of lung resident mesenchymal stem cells into myofibroblasts via the miR-21/PTEN pathway

BACKGROUND

The accumulation of myofibroblasts is the key pathological feature of pulmonary fibrosis (PF). Aberrant differentiation of lung-resident mesenchymal stem cells (LR-MSCs) has been identified as a critical source of myofibroblasts, but the molecular mechanisms underlying this process remain largely unknown. In recent years, N6-methyladenosine (m6A) RNA modification has been implicated in fibrosis development across diverse organs; however, its specific role in promoting the differentiation of LR-MSCs into myofibroblasts in PF is not well defined.

METHODS

In this study, we examined the levels of m6A RNA methylation and the expression of its regulatory enzymes in both TGF-β1-treated LR-MSCs and fibrotic mouse lung tissues. The downstream target genes of m6A and their related pathways were identified according to a literature review, bioinformatic analysis and experimental verification. We also assessed the expression levels of myofibroblast markers in treated LR-MSCs and confirmed the involvement of the above-described pathway in the aberrant differentiation direction of LR-MSCs under TGF-β1 stimulation by overexpressing or knocking down key genes within the pathway.

RESULTS

Our results revealed that METTL3-mediated m6A RNA methylation was significantly upregulated in both TGF-β1-treated LR-MSCs and fibrotic mouse lung tissues. This process directly led to the aberrant differentiation of LR-MSCs into myofibroblasts by targeting the miR-21/PTEN pathway. Moreover, inhibition of METTL3 or miR-21 and overexpression of PTEN could rescue this abnormal differentiation.

CONCLUSION

Our study demonstrated that m6A RNA methylation induced aberrant LR-MSC differentiation into myofibroblasts via the METTL3/miR-21/PTEN signaling pathway. We indicated a novel mechanism to promote PF progression. Targeting METTL3-mediated m6A RNA methylation and its downstream targets may present innovative therapeutic approaches for the prevention and treatment of PF.

Changes in m6A in Steatotic Liver Disease

Fatty liver disease is one of the major causes of morbidity and mortality worldwide. Fatty liver includes non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), now replaced by a consensus group as metabolic dysfunction-associated steatotic liver disease (MASLD). While excess nutrition and obesity are major contributors to fatty liver, the underlying mechanisms remain largely unknown and therapeutic interventions are limited. Reversible chemical modifications in RNA are newly recognized critical regulators controlling post-transcriptional gene expression. Among these modifications, N6-methyladenosine (m6A) is the most abundant and regulates transcript abundance in fatty liver disease. Modulation of m6A by readers, writers, and erasers (RWE) impacts mRNA processing, translation, nuclear export, localization, and degradation. While many studies focus on m6A RWE expression in human liver pathologies, limitations of technology and bioinformatic methods to detect m6A present challenges in understanding the epitranscriptomic mechanisms driving fatty liver disease progression. In this review, we summarize the RWE of m6A and current methods of detecting m6A in specific genes associated with fatty liver disease.