Integrated analysis of m6A mRNA methylation in rats with monocrotaline-induced pulmonary arterial hypertension

Understanding how methyltransferase-like 3 functions in lung diseases: From pathogenesis to clinical application

Lung diseases have complex pathogenesis and treatment challenges, showing an obvious increase in the rate of diagnosis and death every year. Therefore, elucidating the mechanism for their pathogenesis and treatment ineffective from novel views is essential and urgent. Methyltransferase-like 3 (METTL3) is a novel post-transcriptional regulator for gene expression that has been implicated in regulating lung diseases, including that observed in chronic conditions such as pulmonary fibrosis (PF), pulmonary arterial hypertension (PAH), and chronic obstructive pulmonary disease (COPD), as well as acute conditions such as pneumonia, severe acute respiratory syndrome coronavirus 2 infection, and sepsis-induced acute respiratory distress syndrome. Notably, a comprehensive summary and analysis of findings from these studies might help understand lung diseases from the novel view of METTL3-regulated mechanism, however, such a review is still lacking. Therefore, this review aims to bridge such shortage by summarising the roles of METTL3 in lung diseases, establishing their interrelationships, and elucidating the potential applications of METTL3 regarding diagnosis, treatment, and prognosis. The analysis collectively suggests METTL3 is contributable to the onset and progression of these lung diseases, thereby prospecting METTL3 as a valuable biomarker for their diagnosis, treatment, and prognosis. In conclusion, this review offers elucidation into the correlation between METTL3 and lung diseases in both research and clinical settings and highlights potential avenues for exploring the roles of METTL3 in the respiratory system.

STING Contributes to Pulmonary Hypertension by Targeting IFN and BMPR2 Signaling through Regulating of F2RL3

Pulmonary hypertension (PH) is an incurable disease characterized by pulmonary vascular remodeling. Endothelial injury and inflammation are the key triggers of disease initiation. Recent findings suggest that STING (stimulator of IFN genes) activation plays a critical role in endothelial dysfunction and IFN signaling. Here, we investigated the involvement of STING in the pathogenesis of PH. Patients with PH and rodent PH model samples, a Sugen 5416/hypoxia PH model, and pulmonary artery endothelial cells (PAECs) were used to evaluate the hypothesis. We found that the cyclic guanosine monophosphate-AMP synthase-STING signaling pathway was activated in lung tissues from rodent PH models and patients with PH and in TNF-α-induced PAECs in vitro. Specifically, STING expression was significantly elevated in the endothelial cells in PH disease settings. In the Sugen 5416/hypoxia mouse model, genetic knockout or pharmacological inhibition of STING prevented the progression of PH. Functionally, knockdown of STING reduced the proliferation and migration of PAECs. Mechanistically, STING transcriptionally regulates its binding partner F2RL3 (F2R-like thrombin or trypsin receptor 3) through the STING-NF-κB axis, which activated IFN signaling and repressed BMPR2 (bone morphogenetic protein receptor 2) signaling both in vitro and in vivo. Further analysis revealed that F2RL3 expression was increased in PH settings and identified negative feedback regulation of F2RL3/BMPR2 signaling. Accordingly, a positive correlation of expression amounts between STING and F2RL3/IFN-stimulated genes was observed in vivo. Our findings suggest that STING activation in PAECs plays a critical role in the pathobiology of PH. Targeting STING may be a promising therapeutic strategy for preventing the development of PH.

METTL3-Driven m6A Modification of RBPJ Promotes Vascular Remodeling in Pulmonary Hypertension

The dysregulation of N6-methyladenosine (m6A) RNA modification is widely recognized for its crucial roles in various diseases, including pulmonary hypertension (PH). Prior studies have highlighted the significant role of METTL3 in the pathogenesis of PH. Nevertheless, the potential and underlying mechanisms of METTL3 and its inhibitors as targets for PH treatment require further elucidation. In this study, we observed increased levels of METTL3 in various rodent models of PH. In vitro studies revealed that METTL3 silencing or treatment with STM2457, a specific METTL3 inhibitor, attenuated the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) stimulated by platelet-derived growth factor-BB (PDGF-BB) or hypoxia. Moreover, in vivo experiments using AAV9-mediated METTL3 silencing or STM2457 inhibition demonstrated improvement in SU5416/hypoxia-induced PH in mice. Additionally, m6A RNA immunoprecipitation analysis identified RBPJ as a gene regulated by METTL3 in rodent models of PH. Loss-of-function studies showed that silencing RBPJ could attenuate the changes in the proliferation and migration of PASMCs induced by PDGF-BB or hypoxia. Further studies indicated that METTL3 and YTHDF1 regulate RBPJ mRNA expression in an m6A-dependent manner. These findings indicated that targeting METTL3 may be a promising therapeutic strategy for treating PH, and modulation of RBPJ could offer a potential intervention mechanism.

The potential of RNA methylation in the treatment of cardiovascular diseases

RNA methylation has emerged as a dynamic regulatory mechanism that impacts gene expression and protein synthesis. Among the known RNA methylation modifications, N6-methyladenosine (m6A), 5-methylcytosine (m5C), 3-methylcytosine (m3C), and N7-methylguanosine (m7G) have been studied extensively. In particular, m6A is the most abundant RNA modification and has attracted significant attention due to its potential effect on multiple biological processes. Recent studies have demonstrated that RNA methylation plays an important role in the development and progression of cardiovascular disease (CVD). To identify key pathogenic genes of CVD and potential therapeutic targets, we reviewed several common RNA methylation and summarized the research progress of RNA methylation in diverse CVDs, intending to inspire effective treatment strategies.

Regulatory roles of RNA methylation in vascular lesions in ocular and cardiopulmonary diseases

RNA methylation is a widespread regulatory mechanism that controls gene expression in physiological processes. In recent years, the mechanisms and functions of RNA methylation under diseased conditions have been increasingly unveiled by RNA sequencing technologies with large scale and high resolution. In this review, the fundamental concept of RNA methylation is introduced, and the common types of transcript methylation and their machineries are described. Then, the regulatory roles of RNA methylation, particularly N6-methyladenosine and 5-methylcytosine, in the vascular lesions of ocular and cardiopulmonary diseases are discussed and compared. The ocular diseases include corneal neovascularization, retinopathy of prematurity, diabetic retinopathy, and pathologic myopia; whereas the cardiopulmonary ailments involve atherosclerosis and pulmonary hypertension. This review hopes to shed light on the common regulatory mechanisms underlying the vascular lesions in these ocular and cardiopulmonary diseases, which may be conducive to developing therapeutic strategies in clinical practice.

Upregulation of eIF2α by m6A modification accelerates the proliferation of pulmonary artery smooth muscle cells in MCT-induced pulmonary arterial hypertension rats

Pulmonary arterial hypertension (PAH) is a malignant cardiovascular disease. Eukaryotic initiation factor 2α (eIF2α) plays an important role in the proliferation of pulmonary artery smooth muscle cells (PASMCs) in hypoxia-induced pulmonary hypertension (HPH) rats. However, the regulatory mechanism of eIF2α remains poorly understood in PAH rats. Here, we discover eIF2α is markedly upregulated in monocrotaline (MCT)-induced PAH rats, eIF2α can be upregulated by mRNA methylation, and upregulated eIF2α can promote PASMC proliferation in MCT-PAH rats. GSK2606414, eIF2α inhibitor, can downregulate the expression of eIF2α and alleviate PASMC proliferation in MCT-PAH rats. And we further discover the mRNA of eIF2α has a common sequence with N 6-methyladenosine (m6A) modification by bioinformatics analysis, and the expression of METTL3, WTAP, and YTHDF1 is upregulated in MCT-PAH rats. These findings suggest a potentially novel mechanism by which eIF2α is upregulated by m6A modification in MCT-PAH rats, which is involved in the pathogenesis of PAH.

Tumor microenvironment characteristics and prognostic role of m6A modification in lung squamous cell carcinoma

Background

It has recently been determined that N6-methyladenosine (m6A) RNA methylation regulators have prominent effects on several cancers. However, the potential role of m6A modification in lung squamous cell carcinoma (LUSC) remains unclear.

Methods

We evaluated the modification pattern of m6A and studied the biological function of m6A regulators in LUSC. Then, we constructed the m6Ascore to predict the prognosis of LUSC and analyzed the relationship between the m6Ascore and tumor mutation burden, immune cell infiltration, and immunotherapy.

Result

In the unsupervised consensus cluster analysis, three different m6Aclusters were identified, which correspond to an immune activation state, a moderate immune activation state, and an immune tolerance state. Forty-two genes related to the m6A phenotype were used to construct the m6Ascore; subsequently, multiple validations of the m6Ascore were carried out to determine the relationship between the score and immune cell infiltration and response to CTLA-4/PD-1 inhibitor treatment. Further analysis revealed that the m6Ascore could effectively predict the prognosis of LUSC and that the m6A phenotype-related genes, FAM162A and LOM4, might be potential biomarkers.

Conclusion

These findings highlight the potential role of m6A modification in the prognosis, TME, and immunotherapy of LUSC and have profound implications for developing more effective personalized treatment strategies for LUSC.

Endothelial downregulation of nuclear m6A reader YTHDC1 promotes pulmonary vascular remodeling in sugen hypoxia model of pulmonary hypertension

Background

Pulmonary hypertension (PH) is characterized with vascular remodeling, which is intiated by vascular endothelial dysfunction. N6-methyladenosine (m6A) modification mediates gene expression in many ways including mediating RNA degradation, splicing, nuclear export et al. m6A modification have been found to be associated with the development of PH. However, the role of m6A regulators in pulmonary artery endothelial cells (PAECs) dysfunction of PH is still under research.

Methods

The expression levels of m6A regulators in PAECs were analyzed with the single-cell sequencing Data(scRNA). Next, the target differentially expressed genes (DEGs) of m6A regulators in PAECs were functionally annotated. The analysis of cellular interactions included the examination of receptor-ligand pairs regulated by m6A regulators. Pseudo-time trajectory analyses and a ceRNA network involving lncRNAs, miRNAs, and mRNAs were conducted in PAECs. Furthermore, microarray data (GSE180169) for Sugen Hypoxia PH (SuHx PH) mouse models was screened for DEGs and m6A regulators in PAECs. Moreover, the expression of YTHDC1 in the lung samples of SuHx PH models was determined using immunofluorescence. In vitro, the mRNA expression of YTHDC1 in HPAECs under hypoxia conditions was detected. The effect of YTHDC1 recombinant protein on HPAEC proliferation was detected by Cell Counting Kit-8 (CCK8).

Results

Dysregulation of m6A regulators was observed in mouse PAECs. The m6A reader of YTHDC1 was decreased in PAECs in scRNA data and RNAseq data of isolated PAECs of SuHx PH models. Downregulation of YTHDC1 was caused by hypoxia in PAECs in vitro and similar results was observed in PAECs of SuHx PH mouse models. Next, YTHDC1 recombinant protein was found to inhibit HPAECs proliferation. The DEGs targeted by YTHDC1 were enriched in angiogenesis, endothelial cell migration, fluid shear stress, and stem cell maintenance. Analysis indicates that interactions among endothelial cells, smooth muscle cells, fibroblasts, and immune cells, mediated by specific YTHDC1 target genes (e.g., PTPRC-MRC1, ITBG2-ICAM1, COL4A1-CD44), contribute to PH development. Also, the YTHDC1 expression were consistent with Thioredoxin interacting protein (TXNIP). What's more, the predicted transcription factors showed that NFKB1, Foxd3 may be involved in the regulation of YTHDC1. Lastly, our data suggest that YTHDC1 may be involved in regulating PAECs dysfunction through lncRNA/miRNA/mRNA network.

Conclusion

For the first time, we analyzed changes in the expression and biological functions of m6A regulators in SuHx PH mouse models. We causatively linked YTHDC1 to PAECs dysfunction, providing novel insight into and opportunities to diagnose and treat PH.

Transcriptome-Wide N6-Methyladenosine Alternations in Pulmonary Arteries of Monocrotaline-Induced Pulmonary Arterial Hypertension in Rats and Novel Therapeutic Targets

N6-methyladenosine (m6A) is a post-transcriptional epigenetic change with transcriptional stability and functionality regulated by specific m6A-modifying enzymes. However, the significance of genes modified by m6A and enzymes specific to m6A regulation in the context of pulmonary arterial hypertension (PAH) remains largely unexplored. MeRIP-seq and RNA-seq were applied to explore variances in m6A and RNA expression within the pulmonary artery tissues of control and monocrotaline-induced PAH rats. Functional enrichments were analyzed using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. To screen candidate m6A-related genes, the STRING and Metascape databases were used to construct a protein-protein interaction network followed by a real-time PCR validation of their expression. The expression level of an m6A regulator was further investigated using immunohistochemical staining, immunofluorescence, and Western blot techniques. Additionally, proliferation assays were conducted on primary rat pulmonary artery smooth muscle cells (PASMCs). We identified forty-two differentially expressed genes that exhibited either hypermethylated or hypomethylated m6A. These genes are predominantly related to the extracellular matrix structure, MAPK, and PI3K/AKT pathways. A candidate gene, centromere protein F (CENPF), was detected with increased expression in the PAH group. Additionally, we first identified an m6A reader, leucine rich pentatricopeptide repeat containing (LRPPRC), which was downregulated in the PAH rat model. The in vitro downregulation of Lrpprc mediated by siRNA resulted in the enhanced proliferation and elevated expression of Cenpf mRNA in primary rat PASMCs. Our study revealed a modified transcriptome-wide m6A landscape and associated regulatory mechanisms in the pulmonary arteries of PAH rats, potentially offering a novel target for therapeutic strategies in the future.

Pulmonary hypertension

Pulmonary hypertension encompasses a range of conditions directly or indirectly leading to elevated pressures within the pulmonary arteries. Five main groups of pulmonary hypertension are recognized, all defined by a mean pulmonary artery pressure of >20 mmHg: pulmonary arterial hypertension (rare), pulmonary hypertension associated with left-sided heart disease (very common), pulmonary hypertension associated with lung disease (common), pulmonary hypertension associated with pulmonary artery obstructions, usually related to thromboembolic disease (rare), and pulmonary hypertension with unclear and/or multifactorial mechanisms (rare). At least 1% of the world's population is affected, with a greater burden more likely in low-income and middle-income countries. Across all its forms, pulmonary hypertension is associated with adverse vascular remodelling with obstruction, stiffening and vasoconstriction of the pulmonary vasculature. Without proactive management this leads to hypertrophy and ultimately failure of the right ventricle, the main cause of death. In older individuals, dyspnoea is the most common symptom. Stepwise investigation precedes definitive diagnosis with right heart catheterization. Medical and surgical treatments are approved for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. There are emerging treatments for other forms of pulmonary hypertension; but current therapy primarily targets the underlying cause. There are still major gaps in basic, clinical and translational knowledge; thus, further research, with a focus on vulnerable populations, is needed to better characterize, detect and effectively treat all forms of pulmonary hypertension.

Comprehensive analysis of m6A methylomes in idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension (IPAH) is a serious and fatal disease. Recently, m6A has been reported to play an important role in the lungs of IPAH patients and experimental pulmonary hypertension models. However, the meaning of m6A mRNAs in the peripheral blood of IPAH patients remains largely unexplored. We aimed to construct a transcriptome-wide map of m6A mRNAs in the peripheral blood of IPAH patients. M6A RNA Methylation Quantification Kit was utilized to measure the total m6A levels in the peripheral blood of IPAH patients. A combination of MeRIP-seq, RNA-seq and bioinformatics analysis was utilized to select m6A-modified hub genes of IPAH. MeRIP-qPCR and RT-qPCR were used to measure the m6A levels and mRNA levels of TP53, RPS27A, SMAD3 and FoxO3 in IPAH patients. Western blot was performed to assess the protein levels of m6A related regulators and m6A related genes in experimental PH animal models, hypoxia-treated and PDGF-BB induced PASMCs. We found that the total m6A levels were increased in peripheral blood of IPAH patients and verified that m6A levels of RPS27A and SMAD3 were significantly elevated and m6A levels of TP53 and FoxO3 were significantly reduced. The mRNA or protein levels of RPS27A, SMAD3, TP53 and FoxO3 were changed in human blood samples, experimental PH animal models and PDGF-BB induced PASMCs. Moreover, METTL3 and YTHDF1 were increased in the hypoxia induced pulmonary hypertension rat model, hypoxia-treated and PDGF-BB induced PASMCs. These finding suggested that m6A may play an important role in IPAH.

N6-Methyladenosine Modifications in Pulmonary Hypertension

BACKGROUND

The most prevalent kind of RNA methylation modification existing in eukaryotes is N6-methyladenosine (m6A), which is a reversible type of posttranscriptional modification.

SUMMARY

Many studies have reported that m6A participates in cell differentiation, self-renewal, invasion, and apoptosis by modifying protein synthesis. Furthermore, m6A modification is also involved in disease progression and pulmonary vascular remodeling in pulmonary hypertension. However, very few researchers have investigated the effect of m6A modifications on pulmonary hypertension.

KEY MESSAGES

Here, we have reviewed the latest research advances in the field of m6A RNA methylation in pulmonary hypertension and explored its regulatory role in pulmonary hypertension development and progression.

Role of histone lactylation interference RNA m6A modification and immune microenvironment homeostasis in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe disease resulting from progressive increases in pulmonary vascular resistance and pulmonary vascular remodeling, ultimately leading to right ventricular failure and even death. Hypoxia, inflammation, immune reactions, and epigenetic modifications all play significant contributory roles in the mechanism of PAH. Increasingly, epigenetic changes and their modifying factors involved in reprogramming through regulation of methylation or the immune microenvironment have been identified. Among them, histone lactylation is a new post-translational modification (PTM), which provides a novel visual angle on the functional mechanism of lactate and provides a promising diagnosis and treatment method for PAH. This review detailed introduces the function of lactate as an important molecule in PAH, and the effects of lactylation on N6-methyladenosine (m6A) and immune cells. It provides a new perspective to further explore the development of lactate regulation of pulmonary hypertension through histone lactylation modification.

Comprehensive analyses of m6A RNA methylation patterns and related immune microenvironment in idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension (IPAH) is a life-threatening disease with a poor prognosis and high heritability, characterized by elevated pulmonary vascular resistance (PVR) and pulmonary artery pressure. N6-methyladenosine (m6A) RNA modification influences many RNA metabolism pathways. However, the position of m6A methylation regulators in IPAH remains unknown. Therefore, the study aims to disclose the function m6A regulators exert in the pathological mechanisms of IPAH and the immune microenvironment involved. The GSE117261 dataset was downloaded from the Gene Expression Omnibus (GEO) to screen the differentially expressed genes (DEGs) between normal and IPAH samples. Functional and pathway enrichment analyses of DEGs were then conducted by Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG). We also identified the differentially-expressed m6A (DEm6A) regulators between normal and IPAH samples. Key m6A regulators related to the prediction of IPAH were selected using the random forest model. The results showed that FMR1, RBM15, HNRNPA2B1 and IGFBP3 were upregulated in IPAH. In contrast, LRPPRC was downregulated. The single sample gene set enrichment analysis (ssGSEA) method was then adopted to estimate the immune microenvironment in distinct m6A clusters and m6A phenotype-related genes (PRGs) clusters, respectively. Furthermore, we calculated the m6A score via principal component analysis (PCA), and the Sankey diagram was selected to present the correlation among the m6A clusters, m6A PRGs clusters and m6A score. Finally, quantitative RT-PCR and Western blotting were used to validate the key genes in human pulmonary artery smooth muscle cells (HPASMCs) treated by human platelet-derived growth factor-BB (PDGF-BB). The relative mRNA and protein expression levels of FMR1 were significantly elevated, however, the relative mRNA and protein expression levels of LRPPRC were downregulated. Besides, the relative mRNA level of HNRNPA2B1 was increased. Generally, this bioinformatics analysis might provoke more insights into diagnosing and treating IPAH.

The role and mechanism of FTO in pulmonary vessels

Pulmonary vascular remodeling (PVR) is the main factor of pulmonary hypertension (PH). The pathological characteristics of PVR are vascular smooth muscle hyperplasia, hypertrophy, and extensive damage. In vivo experiments, the expression of FTO in PH rat lung tissues of different rat models of hypoxia PH was observed by immunohistochemical method. mRNA microarray analysis was used to analyze the differential expressed genes in rat lung tissues. In vitro experiments, we developed models of overexpression and knockdown of FTO to study the effect of FTO protein expression on cell apoptotic, cell cycle, and the abundance of m⁶A. The expression of FTO was increased in PH rats. FTO knockdown can inhibit the proliferation of PASMCs, thereby regulating the cell cycle and reducing the expression of Cyclin D1 and the abundance of m⁶A, while overexpression of FTO leads to increased expression of Cyclin D1 and the abundance of m⁶A. FTO destroys the stability of Cyclin D1 by regulating the abundance of Cyclin D1 m⁶A, causing cell cycle arrest and inducing cell proliferation, thus inducing the occurrence and development of PVR in PH.

Exploring m6A-RNA methylation as a potential therapeutic strategy for acute lung injury and acute respiratory distress syndrome

N6-methyladenosine (m6A) is the most common methylation modification in mammalian messenger RNA (mRNA) and noncoding RNAs. m6A modification plays a role in the regulation of gene expression and deregulation of m6A methylation has been implicated in many human diseases. Recent publications suggest that exploitation of this methylation process may possess utility against acute lung injury (ALI). ALI and its more severe form, acute respiratory distress syndrome (ARDS) are acute, inflammatory clinical syndromes characterized by poor oxygenation and diffuse pulmonary infiltrates. This syndrome is associated with microvascular endothelial dysfunction, subsequent pulmonary hypertension and may ultimately lead to mortality without rigorous and acute clinical intervention. Over the years, many attempts have been made to detect novel therapeutic avenues for research without much success. The urgency for the discovery of novel therapeutic agents has become more pronounced recently given the current pandemic infection of coronavirus disease 2019 (COVID-2019), still ongoing at the time that this review is being written. We review the current landscape of literature regarding ALI and ARDS etiology, pathophysiology, and therapeutics and present a potential role of m6A methylation. Additionally, we will establish the axiomatic principles of m6A methylation to provide a framework. In conclusion, METTL3, or methyltransferase-like 3, the selective RNA methyltransferase for m6A, is a hub of proinflammatory gene expression regulation in ALI, and using a modern drug discovery strategy will identify new and effective ALI drug candidates targeting METTTL3.

Analysis of m7G methylation modification patterns and pulmonary vascular immune microenvironment in pulmonary arterial hypertension

Background

M⁷G methylation modification plays an important role in cardiovascular disease development. Dysregulation of the immune microenvironment is closely related to the pathogenesis of PAH. However, it is unclear whether m⁷G methylation is involved in the progress of PAH by affecting the immune microenvironment.

Methods

The gene expression profile of PAH was obtained from the GEO database, and the m⁷G regulatory factors were analyzed for differences. Machine learning algorithms were used to screen characteristic genes, including the least absolute shrinkage and selection operator, random forest, and support vector machine recursive feature elimination analysis. Constructed a nomogram model, and receiver operating characteristic was used to evaluate the diagnosis of disease characteristic genes value. Next, we used an unsupervised clustering method to perform consistent clustering analysis on m⁷G differential genes. Used the ssGSEA algorithm to estimate the relationship between the m⁷G regulator in PAH and immune cell infiltration and analyze the correlation with disease-characteristic genes. Finally, the listed drugs were evaluated through the screened signature genes.

Results

We identified 15 kinds of m⁷G differential genes. CYFIP1, EIF4E, and IFIT5 were identified as signature genes by the machine learning algorithm. Meanwhile, two m⁷G molecular subtypes were identified by consensus clustering (cluster A/B). In addition, immune cell infiltration analysis showed that activated CD4 T cells, regulatory T cells, and type 2 T helper cells were upregulated in m⁷G cluster B, CD56 dim natural killer cells, MDSC, and monocyte were upregulated in the m⁷G cluster A. It might be helpful to select Calpain inhibitor I and Everolimus for the treatment of PAH.

Conclusion

Our study identified CYFIP1, EIF4E, and IFIT5 as novel diagnostic biomarkers in PAH. Furthermore, their association with immune cell infiltration may facilitate the development of immune therapy in PAH.

Emerging roles of the RNA modifications N6-methyladenosine and adenosine-to-inosine in cardiovascular diseases

Cardiovascular diseases lead the mortality and morbidity disease metrics worldwide. A multitude of chemical base modifications in ribonucleic acids (RNAs) have been linked with key events of cardiovascular diseases and metabolic disorders. Named either RNA epigenetics or epitranscriptomics, the post-transcriptional RNA modifications, their regulatory pathways, components, and downstream effects substantially contribute to the ways our genetic code is interpreted. Here we review the accumulated discoveries to date regarding the roles of the two most common epitranscriptomic modifications, N6-methyl-adenosine (m6A) and adenosine-to-inosine (A-to-I) editing, in cardiovascular disease.

Comprehensive analysis of the expression of N6-methyladenosine RNA methylation regulators in pulmonary artery hypertension

Background: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by pulmonary vascular remodeling. The development of PAH involves N6-methyladenosine (m6A) modification. However, the functional role of m6A regulators in PAH and the underlying regulatory mechanisms remain unknown so far.

Methods: Microarray data (GSE149713) for monocrotaline induced PAH (MCT-PAH) rat models were downloaded and screened for differentially expressed genes (DEGs) and m6A regulators. Next, we screened for differentially expressed m6A regulators in endothelial cells (ECs), smooth muscle cells (SMCs), fibroblasts, interstitial macrophages, NK cells, B cells, T cells, regulatory T cells (Tregs) using scRNA sequencing data. The target DEGs of m6A regulators in ECs, SMCs, fibroblasts, and Tregs were functionally annotated using the Gene Ontology (GO) functional analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. In addition, the cellular interaction analysis was performed to reveal the receptor—ligand pairs regulated by m6A regulators. Pseudo-time trajectory analyses were performed and a ceRNA network of lncRNAs-miRNAs-mRNAs was constructed in SMCs. Furthermore, the RNA transcriptome sequencing data for the SMCs isolated from idiopathic PAH (IPAH) patients (GSE144274) were validated for differentially expressed m6A regulators. Moreover, the HNRNPA2B1 levels in the lung samples from PAH patients and MCT-PAH were determined using immunohistochemistry.

Results: The m6A regulators were observed to be dysregulated in PAH. HNRNPA2B1expression level was increased in the PASMCs of scRNAs and IPAH patients. The target DEGs of HNRNPA2B1 were enriched in the regulation of muscle cell differentiation and vasculature development in PASMCs. The HNRNPA2B1 expression levels determined were consistent with the proliferation-related and collagen synthesis-related gene COL4A1. Moreover, the predicted transcription factors (TFs) foxd2/3 and NFκB could be involved in the regulation of HNRNPA2B1. HNRNPA2B1 might be regulating SMCs proliferation and phenotypic transition via rno-miR-330–3p/TGFβR3 and rno-miR-125a-3p/slc39a1. In addition, HNRNPA2B1 was observed to be highly expressed in the lung samples from MCT-PAH rat models and patients with PAH.

Conclusion: In summary, the present study identified certain key functional m6A regulators that are involved in pulmonary vascular remodeling. The investigation of m6A patterns might be promising and provide biomarkers for diagnosis and treatment of PAH in the future.

Relevance of RNA N6-Methyladenosine Regulators for Pulmonary Fibrosis: Implications for Chronic Hypersensitivity Pneumonitis and Idiopathic Pulmonary Fibrosis

N6-methyladenosine (m6A) modification plays a pivotal role in post-transcriptionally regulating gene expression and biological functions. Nonetheless, the roles of m6A modification in the regulation of chronic hypersensitivity pneumonitis (CHP) and idiopathic pulmonary fibrosis (IPF) remain unclear. Twenty-two significant m6A regulators were selected from differential gene analysis between the control and treatment groups from the GSE150910 dataset. Five candidate m6A regulators (insulin-like growth factor binding protein 2, insulin-like growth factor binding protein 3, YTH domain-containing protein 1, zinc finger CCCH domain-containing protein 13, and methyltransferase-like 3) were screened by the application of a random forest model and nomogram model to predict risks of pulmonary fibrosis. The consensus clustering method was applied to divide the treatment samples into two groups with different m6A patterns (clusters A and B) based on the 22 m6A regulators. Our study performed principal component analysis to obtain the m6A-related score of the 288 samples to quantify the two m6A patterns. The study reveals that cluster A was linked to T helper cell (Th) 2-type cytokines, while the immune infiltration of Th1 cytokines was higher in cluster B. Our results suggest that m6A cluster A is likely related to pulmonary fibrosis, indicating m6A regulators play notable roles in the occurrence of pulmonary fibrosis. The m6A patterns could be considered as biomarkers to identify CHP and IPF, which will be helpful to develop immunotherapy strategies for pulmonary fibrosis in the future.

Insights Into the Role of Platelet-Derived Growth Factors: Implications for Parkinson’s Disease Pathogenesis and Treatment

Parkinson’s disease (PD), the second most common neurodegenerative disease after Alzheimer’s disease, commonly occurs in the elderly population, causing a significant medical and economic burden to the aging society worldwide. At present, there are few effective methods that achieve satisfactory clinical results in the treatment of PD. Platelet-derived growth factors (PDGFs) and platelet-derived growth factor receptors (PDGFRs) are important neurotrophic factors that are expressed in various cell types. Their unique structures allow for specific binding that can effectively regulate vital functions in the nervous system. In this review, we summarized the possible mechanisms by which PDGFs/PDGFRs regulate the occurrence and development of PD by affecting oxidative stress, mitochondrial function, protein folding and aggregation, Ca2+ homeostasis, and cell neuroinflammation. These modes of action mainly depend on the type and distribution of PDGFs in different nerve cells. We also summarized the possible clinical applications and prospects for PDGF in the treatment of PD, especially in genetic treatment. Recent advances have shown that PDGFs have contradictory roles within the central nervous system (CNS). Although they exert neuroprotective effects through multiple pathways, they are also associated with the disruption of the blood–brain barrier (BBB). Our recommendations based on our findings include further investigation of the contradictory neurotrophic and neurotoxic effects of the PDGFs acting on the CNS.

m6A Methylation in Cardiovascular Diseases: From Mechanisms to Therapeutic Potential

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. Recent studies have shown that n6-methyladenosine (m6A) plays a major role in cardiovascular homeostasis and pathophysiology. These studies have confirmed that m6A methylation affects the pathophysiology of cardiovascular diseases by regulating cellular processes such as differentiation, proliferation, inflammation, autophagy, and apoptosis. Moreover, plenty of research has confirmed that m6A modification can delay the progression of CVD via the post-transcriptional regulation of RNA. However, there are few available summaries of m6A modification regarding CVD. In this review, we highlight advances in CVD-specific research concerning m6A modification, summarize the mechanisms underlying the involvement of m6A modification during the development of CVD, and discuss the potential of m6A modification as a therapeutic target of CVD.

m6A RNA methylation: A dynamic regulator of cardiac muscle and extracellular matrix

Post-transcriptional modifications encompass a large group of RNA alterations that control gene expression. Methylation of the N⁶-Adenosine (m⁶A) of mRNA is a prevalent modification which alters the life cycle of transcripts. The roles that m⁶A play in regulating cardiac homeostasis and injury response are an active area of investigation, but it is clear that this chemical modification is a critical controller of fibroblast to myofibroblast transition, cardiomyocyte hypertrophy and division, and the structure and function of the extracellular matrix. Here we discuss the latest findings of m⁶A in cardiac muscle and matrix.