circ-BPTF serves as a miR-486-5p sponge to regulate CEMIP and promotes hypoxic pulmonary arterial smooth muscle cell proliferation in COPD

Chronic hypoxia-induced upregulation of hsa_circ_0005255 attenuates myocardial injury via targeting hsa-miR-3916/FTO/m6A axis

Chronic hypoxia initiates compensatory mechanisms to protect the heart. Circular RNAs (circRNAs), a recently identified class of non-coding RNAs, represent a significant portion of mammalian transcriptome. We aimed to explore the underlying mechanisms of circRNA involvement in chronic hypoxia-related cardiovascular diseases. In the presents study, we firstly observed hsa_circ_0005255 was elevated in myocardial samples collected from patients with cyanotic heart disease through using circRNA array sequencing, which was confirmed both in vivo and in vitro. The upregulation of hsa_circ_0005255 reduced the levels of N6-methyladenosine (m6A) modification and protected cardiomyocytes from chronic hypoxia induced injury. Fat mass and obesity-associated protein (FTO), the classic regulator of methylation, was proved to be regulated by hsa_circ_0005255. Further research verified the direct target interactions of hsa_circ_0005255/hsa-miR-3916 and hsa-miR-3916/FTO. Our findings suggested hsa_circ_0005255 played pivotal protective role in cardiomyocytes via hsa-miR-3916/FTO/m6A axis. We also showed that silencing hsa_circ_0005255 increased myocardial apoptosis and worsened ischemia/reperfusion (I/R) injury in vivo. In addition, the expression of hsa_circ_0005255 in clinical myocardial samples showed a significant negative correlation with myocardial enzyme levels and early clinical outcomes. This study elucidates a novel mechanism that hsa_circ_0005255/hsa-miR-3916/FTO-m6A axis is involved in myocardial adaptation to chronic hypoxia, representing a promising therapeutic target for cardiovascular diseases.

Circulating Non-Coding RNAs as Indicators of Fibrosis and Heart Failure Severity

Heart failure (HF) is a leading cause of morbidity and mortality worldwide, representing a complex clinical syndrome in which the heart's ability to pump blood efficiently is impaired. HF can be subclassified into heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF), each with distinct pathophysiological mechanisms and varying levels of severity. The progression of HF is significantly driven by cardiac fibrosis, a pathological process in which the extracellular matrix undergoes abnormal and uncontrolled remodelling. Cardiac fibrosis is characterized by excessive matrix protein deposition and the activation of myofibroblasts, increasing the stiffness of the heart, thus disrupting its normal structure and function and promoting lethal arrythmia. MicroRNAs, long non-coding RNAs, and circular RNAs, collectively known as non-coding RNAs (ncRNAs), have recently gained significant attention due to a growing body of evidence suggesting their involvement in cardiac remodelling such as fibrosis. ncRNAs can be found in the peripheral blood, indicating their potential as biomarkers for assessing HF severity. In this review, we critically examine recent advancements and findings related to the use of ncRNAs as biomarkers of HF and discuss their implication in fibrosis development.

RNA-binding proteins as a molecular link between COPD and pulmonary hypertension

Pulmonary hypertension (PH) is a vascular disease characterized by remodeling of the pulmonary arteries and right heart failure. Chronic obstructive pulmonary disease (COPD) patients often have PH, which can worsen symptoms and raise morbidity and mortality. There are several reasons for increased pulmonary vascular resistance, pulmonary vascular remodeling, and ultimately the development of PH in COPD. These factors include genetics, inflammation caused by chemicals breathed, and changes in the alveoli seen in COPD and its physiology. Genes involved in mRNA conversion, subcellular localization, splicing, and translation are all finely tuned by RBPs in their post-transcriptional regulation. Erythropoietin regulates cytokines, chemokines, proteins, growth factors, and other pro-inflammatory mediators that change the lung microenvironment. Over the past few years, we have learned more about how RBPs act in PH and COPD. Here, we discuss the existing understanding of RBPs' location in the same pathogenic pathways shared by PH and COPD in order to emphasize their potential relevance as disease determinant/biomarker and, consequently, for possible therapeutic targeting.

Artemisia capillaris with two novel active compounds, Kawarayomogin I and II, inhibits HYBID (KIAA1199) expression as well as hyaluronic acid degradation

Hyaluronic acid (HA) is an important component of the skin's extracellular matrix, and its degradation leads to wrinkles. Hyaluronan-binding protein involved in hyaluronan depolymerization (HYBID) is the main factor responsible for HA degradation in dermis. This study aimed to identify natural plant materials that can effectively suppress HYBID expression and protect HA from degradation. Screening of various plant extracts was performed for the inhibition of histamine-induced mRNA expression of HYBID in normal human dermal fibroblasts (NHDF). The molecular size distribution of HA was evaluated by incubating fluorescein isothiocyanate (FITC)-labeled large HA (1200-1600 kDa) in NHDF for certain time followed by measuring different sizes of FITC-labeled HA in the cultured medium by HPLC. Among 380 plant extracts, we found that Artemisia capillaris flower extract (ACFE) was the most effective agent in both suppressing HYBID expression as well as protecting large HA from degradation. Subsequent mechanism elucidation studies showed that ACFE epigenetically regulates the expression of HYBID by modulating the expression of a specific miRNA, miR-486-5p, which is known to directly target and inhibit HYBID expression. Our active compound search identified 1-caffeoyl-3-hydroxybutane and 3-caffeoyl-1-hydroxybutane in ACFE as new compounds, which we named Kawarayomogin I and Kawarayomogin II, respectively. This is the first report to show that Artemisia capillaris with two novel active compounds inhibits HYBID expression as well as hyaluronic acid degradation, and therefore, could be used as possible agent for cosmeceutical potential.

LncRNA MIR210HG promotes phenotype switching of pulmonary arterial smooth muscle cells through autophagy-dependent ferroptosis pathway

Hypoxic pulmonary hypertension (HPH) is a pathophysiological syndrome in which pulmonary vascular pressure increases under hypoxic stimulation and there is an urgent need to develop emerging therapies for the treatment of HPH. LncRNA MIR210HG is a long non-coding RNA closely related to hypoxia and has been widely reported in a variety of tumor diseases. But its mechanism in hypoxic pulmonary hypertension is not clear. In this study, we identified for the first time the potential effect of MIR210HG on disease progression in HPH. Furthermore, we investigated the underlying mechanism through which elevated levels of MIR210HG promotes the transition from a contractile phenotype to a synthetic phenotype in PASMCs under hypoxia via activation of autophagy-dependent ferroptosis pathway. While overexpression of HIF-2α in PASMCs under hypoxia significantly reversed the phenotypic changes induced by MIR210HG knockdown. We further investigated the potential positive regulatory relationship between STAT3 and the transcription of MIR210HG in PASMCs under hypoxic conditions. In addition, we established both in vivo and in vitro models of HPH to validate the differential expression of specific markers associated with hypoxia. Our findings suggest a potential mechanism of LncRNA MIR210HG in the progression of HPH and offer potential targets for disease intervention and treatment.

Circular RNAs in human diseases

Circular RNAs (circRNAs) are a unique class of RNA molecules formed through back-splicing rather than linear splicing. As an emerging field in molecular biology, circRNAs have garnered significant attention due to their distinct structure and potential functional implications. A comprehensive understanding of circRNAs' functions and potential clinical applications remains elusive despite accumulating evidence of their involvement in disease pathogenesis. Recent research highlights their significant roles in various human diseases, but comprehensive reviews on their functions and applications remain scarce. This review provides an in-depth examination of circRNAs, focusing first on their involvement in non-neoplastic diseases such as respiratory, endocrine, metabolic, musculoskeletal, cardiovascular, and renal disorders. We then explore their roles in tumors, with particular emphasis on exosomal circular RNAs, which are crucial for cancer initiation, progression, and resistance to treatment. By detailing their biogenesis, functions, and impact on disease mechanisms, this review underscores the potential of circRNAs as diagnostic biomarkers and therapeutic targets. The review not only enhances our understanding of circRNAs' roles in specific diseases and tumor types but also highlights their potential as novel diagnostic and therapeutic tools, thereby paving the way for future clinical investigations and potential therapeutic interventions.

Unwinding circular RNA's role in inflammatory pulmonary diseases

Circular RNAs (circRNAs) have emerged as pivotal regulators of gene expression and cellular processes in various physiological and pathological conditions. In recent years, there has been a growing interest in investigating the role of circRNAs in inflammatory lung diseases, owing to their potential to modulate inflammation-associated pathways and contribute to disease pathogenesis. Inflammatory lung diseases, like asthma, chronic obstructive pulmonary disease (COPD), and COVID-19, pose significant global health challenges. The dysregulation of inflammatory responses demonstrates a pivotal function in advancing these diseases. CircRNAs have been identified as important players in regulating inflammation by functioning as miRNA sponges, engaging with RNA-binding proteins, and participating in intricate ceRNA networks. These interactions enable circRNAs to regulate the manifestation of key inflammatory genes and signaling pathways. Furthermore, emerging evidence suggests that specific circRNAs are differentially expressed in response to inflammatory stimuli and exhibit distinct patterns in various lung diseases. Their involvement in immune cell activation, cytokine production, and tissue remodeling processes underscores their possible capabilities as therapeutic targets and diagnostic biomarkers. Harnessing the knowledge of circRNA-mediated regulation in inflammatory lung diseases could lead to the development of innovative strategies for disease management and intervention. This review summarizes the current understanding of the role of circRNAs in inflammatory lung diseases, focusing on their regulatory mechanisms and functional implications.

Exploring the Multifaceted Biologically Relevant Roles of circRNAs: From Regulation, Translation to Biomarkers

CircRNAs are a category of regulatory RNAs that have garnered significant attention in the field of regulatory RNA research due to their structural stability and tissue-specific expression. Their circular configuration, formed via back-splicing, results in a covalently closed structure that exhibits greater resistance to exonucleases compared to linear RNAs. The distinctive regulation of circRNAs is closely associated with several physiological processes, as well as the advancement of pathophysiological processes in several human diseases. Despite a good understanding of the biogenesis of circular RNA, details of their biological roles are still being explored. With the steady rise in the number of investigations being carried out regarding the involvement of circRNAs in various regulatory pathways, understanding the biological and clinical relevance of circRNA-mediated regulation has become challenging. Given the vast landscape of circRNA research in the development of the heart and vasculature, we evaluated cardiovascular system research as a model to critically review the state-of-the-art understanding of the biologically relevant functions of circRNAs. We conclude the review with a discussion of the limitations of current functional studies and provide potential solutions by which these limitations can be addressed to identify and validate the meaningful and impactful functions of circRNAs in different physiological processes and diseases.

Circular RNAs: emerging players in asthma and COPD

Circular RNAs (circRNAs) belong to a unique class of endogenously expressed non-protein-coding RNAs with a distinct circularized structure, characterized by the absence of 5'-cap and 3'-polyadenylate ends. They are generally formed through back-splicing from pre-mRNAs. They serve as regulators of transcription and splicing, and act as sponges for microRNAs (miRNAs) and RNA-binding proteins, thereby modulating the expression of target genes. As a result, they exert a substantial impact on a diverse array of cellular and biological processes, including cell proliferation, migration, inflammation, and oxidative stress. Asthma and COPD are chronic airway conditions that currently have no cure. In recent years, emerging evidence suggests that altered expression of circRNAs in airway, bronchial and immune cells is involved in asthma and COPD pathogenesis. Studies exploring circRNA dysregulation in asthma have showcased their involvement in regulating the proliferation, migration, and inflammation of airway smooth muscle and bronchial epithelial cells, as well as impacting goblet cell metaplasia, Th2 cell differentiation, and macrophage activation, primarily through interactions with miRNAs. Similarly, in COPD, circRNAs have shown altered expression patterns in the blood and lungs of patients, and these changes have been linked to modulating inflammation, oxidative stress, and airway remodeling in preclinical models. Furthermore, certain circRNAs have demonstrated promising potential as diagnostic and prognostic biomarkers for both asthma and COPD. This review delves into the current understanding of the function and molecular mechanisms of circRNAs in asthma and COPD, along with exploring their potential as biomarkers in these respiratory conditions.

circRNA-miRNA-mRNA Deregulated Network in Ischemic Heart Failure Patients

Noncoding RNAs (ncRNAs), which include circular RNAs (circRNAs) and microRNAs (miRNAs), regulate the development of cardiovascular diseases (CVD). Notably, circRNAs can interact with miRNAs, influencing their specific mRNA targets' levels and shaping a competing endogenous RNAs (ceRNA) network. However, these interactions and their respective functions remain largely unexplored in ischemic heart failure (IHF). This study is aimed at identifying circRNA-centered ceRNA networks in non-end-stage IHF. Approximately 662 circRNA-miRNA-mRNA interactions were identified in the heart by combining state-of-the-art bioinformatics tools with experimental data. Importantly, KEGG terms of the enriched mRNA indicated CVD-related signaling pathways. A specific network centered on circBPTF was validated experimentally. The levels of let-7a-5p, miR-18a-3p, miR-146b-5p, and miR-196b-5p were enriched in circBPTF pull-down experiments, and circBPTF silencing inhibited the expression of HDAC9 and LRRC17, which are targets of miR-196b-5p. Furthermore, as suggested by the enriched pathway terms of the circBPTF ceRNA network, circBPTF inhibition elicited endothelial cell cycle arrest. circBPTF expression increased in endothelial cells exposed to hypoxia, and its upregulation was confirmed in cardiac samples of 36 end-stage IHF patients compared to healthy controls. In conclusion, circRNAs act as miRNA sponges, regulating the functions of multiple mRNA targets, thus providing a novel vision of HF pathogenesis and laying the theoretical foundation for further experimental studies.

Research on the biological mechanism and potential application of CEMIP

Cell migration-inducing protein (CEMIP), also known as KIAA1199 and hyaluronan-binding protein involved in hyaluronan depolymerization, is a new member of the hyaluronidase family that degrades hyaluronic acid (HA) and remodels the extracellular matrix. In recent years, some studies have reported that CEMIP can promote the proliferation, invasion, and adhesion of various tumor cells and can play an important role in bacterial infection and arthritis. This review focuses on the pathological mechanism of CEMIP in a variety of diseases and expounds the function of CEMIP from the aspects of inhibiting cell apoptosis, promoting HA degradation, inducing inflammatory responses and related phosphorylation, adjusting cellular microenvironment, and regulating tissue fibrosis. The diagnosis and treatment strategies targeting CEMIP are also summarized. The various functions of CEMIP show its great potential application value.

The vascular perspective on acute and chronic lung disease

The pulmonary vasculature has been frequently overlooked in acute and chronic lung diseases, such as acute respiratory distress syndrome (ARDS), pulmonary fibrosis (PF), and chronic obstructive pulmonary disease (COPD). The primary emphasis in the management of these parenchymal disorders has largely revolved around the injury and aberrant repair of epithelial cells. However, there is increasing evidence that the vascular endothelium plays an active role in the development of acute and chronic lung diseases. The endothelial cell network in the capillary bed and the arterial and venous vessels provides a metabolically highly active barrier that controls the migration of immune cells, regulates vascular tone and permeability, and participates in the remodeling processes. Phenotypically and functionally altered endothelial cells, and remodeled vessels, can be found in acute and chronic lung diseases, although to different degrees, likely because of disease-specific mechanisms. Since vascular remodeling is associated with pulmonary hypertension, which worsens patient outcomes and survival, it is crucial to understand the underlying vascular alterations. In this Review, we describe the current knowledge regarding the role of the pulmonary vasculature in the development and progression of ARDS, PF, and COPD; we also outline future research directions with the hope of facilitating the development of mechanism-based therapies.