RNA-binding proteins in vascular inflammation and atherosclerosis

Protein arginine methyltransferase-6 regulates heterogeneous nuclear ribonucleoprotein-F expression and is a potential target for the treatment of neuropathic pain

JOURNAL/nrgr/04.03/01300535-202509000-00029/figure1/v/2024-11-05T132919Z/r/image-tiff Protein arginine methyltransferase-6 participates in a range of biological functions, particularly RNA processing, transcription, chromatin remodeling, and endosomal trafficking. However, it remains unclear whether protein arginine methyltransferase-6 modifies neuropathic pain and, if so, what the mechanisms of this effect. In this study, protein arginine methyltransferase-6 expression levels and its effect on neuropathic pain were investigated in the spared nerve injury model, chronic constriction injury model and bone cancer pain model, using immunohistochemistry, western blotting, immunoprecipitation, and label-free proteomic analysis. The results showed that protein arginine methyltransferase-6 mostly co-localized with β-tubulin III in the dorsal root ganglion, and that its expression decreased following spared nerve injury, chronic constriction injury and bone cancer pain. In addition, PRMT6 knockout (Prmt6-/-) mice exhibited pain hypersensitivity. Furthermore, the development of spared nerve injury-induced hypersensitivity to mechanical pain was attenuated by blocking the decrease in protein arginine methyltransferase-6 expression. Moreover, when protein arginine methyltransferase-6 expression was downregulated in the dorsal root ganglion in mice without spared nerve injury, increased levels of phosphorylated extracellular signal-regulated kinases were observed in the ipsilateral dorsal horn, and the response to mechanical stimuli was enhanced. Mechanistically, protein arginine methyltransferase-6 appeared to contribute to spared nerve injury-induced neuropathic pain by regulating the expression of heterogeneous nuclear ribonucleoprotein-F. Additionally, protein arginine methyltransferase-6-mediated modulation of heterogeneous nuclear ribonucleoprotein-F expression required amino acids 319 to 388, but not classical H3R2 methylation. These findings indicated that protein arginine methyltransferase-6 is a potential therapeutic target for the treatment of peripheral neuropathic pain.

Pyroptosis was suppressed by 20-hydroxyecdysone through Lin28b-mediated let-7d in vascular endothelial cells

20-hydroxyecdysone (20E), a natural polyhydroxylated steroid, has exhibited anti-inflammatory effects across various diseases. This study investigates the potential connection between 20E's anti-inflammatory properties and the RNA-binding protein Lin28b, which is notably upregulated in TNF-α-stimulated endothelial cells. Herein, we discovered that 20E can selectively downregulate Lin28b expression without affecting its paralog Lin28a. Notably, 20E treatment could significantly attenuate pyroptosis, an inflammatory form of programmed cell death, as evidenced by reduced IL-1β and LDH release, and fewer propidium iodide (PI)-positive cells. Subsequent protein analysis revealed that 20E inhibited the enhanced expressions of key pyroptosis-associated proteins, GSDMD, GSDMD-N, and GSDME-N. Besides, this suppression of Lin28b and pyroptosis may be partially mediated through TNFR1. Additionally, 20E upregulated let-7 miRNA, particularly let-7d, a critical downstream target of Lin28b. To elucidate the role of Lin28b in 20E-mediated pyroptosis attenuation, we performed Lin28b overexpression and silencing experiments. Overexpressing Lin28b negated 20E's inhibition of LDH release and PI-related fluorescence, exacerbating GSDMD and GSDME cleavage. Conversely, Lin28b knockdown augmented the suppressive effect of 20E on pyroptosis, which was reversed by a let-7d inhibitor. Co-transfection with let-7d mimic and Lin28b plasmid demonstrated let-7d's role in mitigating pyroptosis aggravated by Lin28b overexpression. Overall, this study demonstrates that 20E may mitigate GSDMD and GSDME-mediated pyroptosis in HUVECs through the Lin28b/let-7d-dependent signaling pathway. These results highlight the potential of 20E as a promising inhibitor of pyroptosis, offering new insights into its anti-inflammatory mechanisms.

SAMD4A inhibits abdominal aortic aneurysm development and VSMC phenotypic transformation through targeting KDM2B

INTRODUCTION

Abdominal aortic aneurysm (AAA) is a fatal vascular disease without effective drug treatments. Pathological vascular smooth muscle cell (VSMC) phenotypic transformation is the underlying cause of AAA. However, the underlying mechanism has not been fully elucidated.

OBJECTIVE

We aimed to determine whether the RNA binding protein SAMD4A suppresses VSMC phenotype transformation and inhibits AAA formation.

METHODS

Single-cell RNA sequencing (scRNA-seq) was conducted to reveal smooth muscle cell phenotypic heterogeneity and RNA-binding protein dysregulation during AAA formation. A pancreatic elastase (PPE)-induced mouse AAA model was generated to confirm the function of SAMD4A in vivo. RNA-seq combined with RNA immunoprecipitation (RIP) sequencing and chromatin immunoprecipitation (ChIP)-qPCR was used for mechanistic exploration.

RESULTS

We identified 3 smooth muscle cell subtypes, and demonstrated their transformation from contractile to inflammatory-like VSMCs during AAA formation. SAMD4A expression was increased in contractile VSMCs and significantly reduced in AAAs. The results of functional experiments revealed that VSMC-specific knockout of SAMD4A exacerbated PPE-induced AAA formation, whereas VSMC knock-in attenuated AAA formation. SAMD4A regulated VSMC contraction by binding to KDM2B. Further in vivo studies revealed that overexpression of KDM2B abolished the protective effect of SAMD4A in AAA. ChIP-qPCR demonstrated that KDM2B suppressed the transcription of VSMC contractile markers by binding to their promoters and reducing H3K4me3 and H3K36me2 levels.

CONCLUSIONS

SAMD4A inhibits AAA development and VSMC phenotypic transformation by targeting KDM2B. This work highlights the potential of SAMD4A as a new therapeutic option to prevent AAA formation.

HSPB1 Orchestrates the Inflammation-Associated Transcriptome Profile of Atherosclerosis in HUVECs

BACKGROUND

Atherosclerosis (AS), with a profound inflammatory response, is the basis of cardiovascular diseases. Previous reports showed that heat shock protein family B member 1 (HSPB1) has a protective effect against AS, but the specific mechanism is still unclear. In this study, we aim to explore the functions and downstream targets of HSPB1 in human umbilical vein endothelial cells (HUVECs).

METHODS

Expression of the HSPB1 gene was knocked down in HUVECs. Cellular phenotype was then assessed and transcriptome data (RNA-seq) was analyzed to identify the potential targets regulated by HSPB1. Moreover, RNA-seq data for human fibroatheroma (GSE104140) from the gene expression omnibus (GEO) database was re-analyzed to verify the targets of HSPB1 in AS.

RESULTS

Silencing of HSPB1 significantly reduced apoptosis (p < 0.0001) and increased the proliferation (p < 0.05) of HUVECs. The 608 differentially expressed genes (DEGs) were identified after HSPB1 knockdown, including 423 upregulated genes. DEGs, including CXCL1, CXCL8, CXCL2, TRIB3, GAS5, SELE, and TNIP1, were enriched in inflammatory and immune response pathways. HSPB1 was also shown to affect alternative splicing patterns of hundreds of genes, especially those enriched in apoptotic processes, including ACIN1, IFI27, PAK4, UBE2D3, and FIS1. An overlapping gene set was found between the HSPB1-regulated and AS-induced transcriptome. This included 171 DEGs and 250 alternatively spliced genes that were also enriched in inflammatory/immune response- and apoptosis-associated pathways, respectively.

CONCLUSION

In summary, HSPB1 knockdown modulates the proliferation and apoptosis of HUVECs by regulating RNA levels and alternative splicing patterns. HSPB1 plays an important role in AS pathogenesis by modulating the inflammatory and immune response. This study provides novel insights for the investigation of future AS therapeutic strategies.

The role of splicing events in the inflammatory response of atherosclerosis: molecular mechanisms and modulation

Atherosclerosis is a chronic inflammatory disease characterized by persistent inflammatory responses throughout all stages of its progression. Modulating these inflammatory responses is a promising avenue for the development of cardiovascular disease therapies. Splicing events modulate gene expression and diversify protein functionality, exerting pivotal roles in the inflammatory mechanisms underlying atherosclerosis. These insights may provide novel opportunities for developing anti-inflammatory therapies for this disease. This article systematically discusses the diverse splice variants and how splicing events impact the inflammatory response in atherosclerosis via endothelial cells, macrophages, and vascular smooth muscle cells, highlighting their underlying molecular mechanisms and implications. Furthermore, this study summarizes clinical evidence supporting splicing-related molecules as diagnostic biomarkers and therapeutic targets in atherosclerosis. Lastly, we outline the current challenges and future research directions concerning splicing events and inflammatory responses in atherosclerosis. This offers a novel perspective and evidence for formulating new therapeutic strategies aimed at lowering the risk of atherosclerosis.

The Biological Mechanisms and Clinical Roles of RNA-Binding Proteins in Cardiovascular Diseases

RNA-binding proteins (RBPs) have pivotal roles in cardiovascular biology, influencing various molecular mechanisms underlying cardiovascular diseases (CVDs). This review explores the significant roles of RBPs, focusing on their regulation of RNA alternative splicing, polyadenylation, and RNA editing, and their impact on CVD pathogenesis. For instance, RBPs are crucial in myocardial injury, contributing to disease progression and repair mechanisms. This review systematically analyzes the roles of RBPs in myocardial injury, arrhythmias, myocardial infarction, and heart failure, revealing intricate interactions that influence disease outcomes. Furthermore, the potential of RBPs as therapeutic targets for cardiovascular dysfunction is explored, highlighting the advances in drug development and clinical research. This review also discusses the emerging role of RBPs as biomarkers for cardiovascular diseases, offering insights into their diagnostic and prognostic potential. Despite significant progress, current research faces several limitations, which are critically examined. Finally, this review identifies the major challenges and outlines future research directions to advance the understanding and application of RBPs in cardiovascular medicine.

RNA-binding proteins in cardiovascular biology and disease: the beat goes on

Cardiac development and function are becoming increasingly well understood from different angles, including signalling, transcriptional and epigenetic mechanisms. By contrast, the importance of the post-transcriptional landscape of cardiac biology largely remains to be uncovered, building on the foundation of a few existing paradigms. The discovery during the past decade of hundreds of additional RNA-binding proteins in mammalian cells and organs, including the heart, is expected to accelerate progress and has raised intriguing possibilities for better understanding the intricacies of cardiac development, metabolism and adaptive alterations. In this Review, we discuss the progress and new concepts on RNA-binding proteins and RNA biology and appraise them in the context of common cardiovascular clinical conditions, from cell and organ-wide perspectives. We also discuss how a better understanding of cardiac RNA-binding proteins can fill crucial knowledge gaps in cardiology and might pave the way to developing better treatments to reduce cardiovascular morbidity and mortality.

Cold-Inducible RNA Binding Protein Impedes Breast Tumor Growth in the PyMT Murine Model for Breast Cancer

RNA binding proteins (RBPs) post-transcriptionally regulate gene expression by associating with regulatory sequences in the untranslated regions of mRNAs. Cold-inducible RBP (CIRP) is a stress-induced RBP that was recently shown to modulate inflammation in response to cellular stress, where it increases or decreases pro-tumorigenic (proinflammatory) cytokines in different contexts. CIRP expression is altered in several cancers, including breast cancer, but the effects of CIRP on inflammation in breast cancer is not known. Here, we investigate if CIRP alters growth and the inflammatory profile of breast tumors. Transgenic mice overexpressing CIRP in the mammary epithelium were crossed with the PyMT mouse model of breast cancer, and the effects on both early and late tumorigenesis and inflammation were assessed. The effects of CIRP knockdown were also assessed in Py2T cell grafts. Overexpression of CIRP led to decreased tumorigenesis in the PyMT mouse model. Conversely, the knockdown of CIRP in Py2T cell grafts led to increased tumor growth. Luminex cytokine assays assessed the effects on the inflammatory environment. CIRP/PyMT mammary glands/mammary tumors and serum had decreased cytokines that promote inflammation, angiogenesis, and metastasis compared to PyMT mammary glands and serum, documenting a shift towards an environment less supportive of tumorigenesis. CIRP overexpression also decreased CD4+ helper T cells and increased CD8+ cytotoxic T cells in mammary tumors. Overall, these data support a role for CIRP as a potent antitumor molecule that suppresses both local and systemic pro-tumorigenic inflammation.

Inflammation, atherosclerosis and hypertension: the impact of depression and stress on their complex relationship

This future perspective analyzes the complex relationship between inflammation and atherosclerosis and arterial hypertension. The involvement of inflammation in atherosclerosis has led to research therapies that target inflammation to prevent or treat cardiovascular disease. This aspect has recently been included in the treatment management of residual cardiovascular risk. The recent pandemic has exacerbated cardiovascular risk both through an increase in unhealthy lifestyle behaviors and through the reduction of cardiovascular screening. What actions to take? Primary prevention campaigns for healthy subjects with specific attention to young people.

Transcriptome-wide N6-methyladenosine methylation profile of atherosclerosis in mice

BACKGROUND

Atherosclerosis (AS) is a critical pathological event during the progression of cardiovascular diseases. It exhibits fibrofatty lesions on the arterial wall and lacks effective treatment. N6-methyladenosine (m6A) is the most common modification of eukaryotic RNA and plays an important role in regulating the development and progression of cardiovascular diseases. However, the role of m6A modification in AS remains largely unknown. Therefore, in this study, we explored the transcriptome distribution of m6A modification in AS and its potential mechanism.

METHODS

Methylation Quantification Kit was used to detect the global m6A levels in the aorta of AS mice. Western blot was used to analyze the protein level of methyltransferases. Methylated RNA immunoprecipitation with next-generation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were used to obtain the first transcriptome range analysis of the m6A methylene map in the aorta of AS mice, followed by bioinformatics analysis. qRT-PCR and MeRIP-qRT-PCR were used to measure the mRNA and m6A levels in target genes.

RESULTS

The global m6A and protein levels of methyltransferase METTL3 were significantly increased in the aorta of AS mice. However, the protein level of demethylase ALKBH5 was significantly decreased. Through MeRIP-seq, we obtained m6A methylation maps in AS and control mice. In total, 26,918 m6A peaks associated with 13,744 genes were detected in AS group, whereas 26,157 m6A peaks associated with 13,283 genes were detected in the control group. Peaks mainly appeared in the coding sequence (CDS) regions close to the stop codon with the RRACH motif. Moreover, functional enrichment analysis demonstrated that m6A-containing genes were significantly enriched in AS-relevant pathways. Interestingly, a negative correlation between m6A methylation abundance and gene expression level was found through the integrated analysis of MeRIP-seq and RNA-seq data. Among the m6A-modified genes, a hypo-methylated but up-regulated (hypo-up) gene Fabp5 may be a potential biomarker of AS.

CONCLUSIONS

Our study provides transcriptome-wide m6A methylation for the first time to determine the association between m6A modification and AS progression. Our study lays a foundation for further exploring the pathogenesis of AS and provides a new direction for the treatment of AS.

Functions of RNA-Binding Proteins in Cardiovascular Disease

Gene expression is under tight regulation from the chromatin structure that regulates gene accessibility by the transcription machinery to protein degradation. At the transcript level, this regulation falls on RNA-binding proteins (RBPs). RBPs are a large and diverse class of proteins involved in all aspects of a transcript's lifecycle: splicing and maturation, localization, stability, and translation. In the past few years, our understanding of the role of RBPs in cardiovascular diseases has expanded. Here, we discuss the general structure and function of RBPs and the latest discoveries of their role in pulmonary and systemic cardiovascular diseases.