Circular RNAs Act as miRNA Sponges

CircMYO9A inhibits influenza A virus replication by dampening haemagglutinin cleavage via increasing SERPINE1/PAI-1 expression

Circular RNAs (circRNAs) represent a class of widespread and diverse covalently closed circular endogenous RNAs that play critical roles in regulating gene expression in mammals. However, the roles and regulatory mechanisms of circRNAs during influenza A virus (IAV) infection remain largely unexplored. In this study, we screened the circRNA transcription profiles of WSN-infected cells to identify circRNAs involved in viral replication and identified a novel differentially expressed circular RNA, circMYO9A. Mechanistically, circMYO9A acts as a competing endogenous RNA (ceRNA) for SERPINE1/PAI-1 by sponging miR-6059-3p, thereby increasing SERPINE1/PAI-1 expression, which restricts IAV haemagglutinin cleavage and subsequently reduces the infectivity of progeny viruses. Importantly, our findings demonstrate that circMYO9A significantly inhibits viral replication in the lungs of infected mice, potentially increasing their survival during IAV infection. These results demonstrate that circRNAs play crucial roles in inhibiting IAV replication and provide novel insights into potential therapeutic strategies involving circRNAs.

Circular RNAs in gynecological cancer: From molecular mechanisms to clinical applications (Review)

Circular RNAs (circRNAs) have emerged as promising biomarkers and therapeutic targets in gynecological cancer. The present review explored developments in circRNA research in ovarian, endometrial and cervical cancer. circRNA biogenesis, functions and roles in cancer pathogenesis have been discussed, focusing on their potential as diagnostic and prognostic markers. Furthermore, circRNAs mechanisms of action, including miRNA sponging, protein scaffolding and peptide encoding were examined, highlighting specific circRNAs implicated in each cancer type and their clinical significance. The unique properties of circRNAs, such as stability and tissue-specific expression, make them ideal candidates for biomarker development. By synthesizing the currently available literature and identifying future research directions, the present review underscored circRNAs potential to improve gynecological cancer management through novel diagnostic tools, prognostic markers and targeted therapies.

Exploring the role of exosomal and non-exosomal non-coding RNAs in Kawasaki disease: Implications for diagnosis and therapeutic strategies against coronary artery aneurysms

Kawasaki disease (KD) is an acute vasculitis primarily affecting children, with a potential risk of developing coronary artery aneurysms (CAAs) and cardiovascular complications. The emergence of non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), has provided insights into Kawasaki disease pathogenesis and opened new avenues for diagnosis and therapeutic intervention. Furthermore, polymorphism analysis of ncRNA genes offers significant insights into genetic predisposition to Kawasaki disease, facilitating tailored treatment approaches and risk assessment to improve patient outcomes. Exosomal ncRNAs, which are ncRNAs encapsulated within extracellular vesicles, have garnered significant attention as potential biomarkers for Kawasaki disease and CAA due to their stability and accessibility in biological fluids. This review comprehensively discusses the biogenesis, components, and potential of exosomal and non-exosomal ncRNAs in Kawasaki disease diagnosis and prognosis prediction. It also highlights the roles of non-exosomal ncRNAs, such as miRNAs, lncRNAs, and circRNAs, in Kawasaki disease pathogenesis and their implications as therapeutic targets. Additionally, the review explores the current diagnostic and therapeutic approaches for Kawasaki disease and emphasizes the need for further research to validate these ncRNA-based biomarkers in diverse populations and clinical settings.

The IGF2BP2-circ-DAPK1 axis promotes high-glucose-induced ferroptosis of HUVECs by decreasing NQO1 expression

Circular RNAs (circRNAs) are non-coding RNAs with covalently closed loop structures that participate in various biological processes. However, the functions of many circRNAs remain unclear. Endothelial cell dysfunction, which involves abnormal ferroptosis, a unique form of regulated cell death, is a characteristic of various diseases. However, the mechanisms governing ferroptosis in endothelial cells are not fully understood. Here, we investigated the impact of a novel circRNA, circ-DAPK1, on ferroptosis in human umbilical vein endothelial cells (HUVECs) under high-glucose conditions. Our data showed that high-glucose conditions upregulate circ-DAPK1 expression in HUVECs. Overexpression of circ-DAPK1 induced ferroptosis in HUVECs, whereas depletion of circ-DAPK1 mitigated the ferroptosis triggered by high-glucose treatment. Inhibition of ferroptosis reversed the decrease in cell viability induced by high glucose or circ-DAPK1 overexpression. Using RNA immunoprecipitation analyses, we identified several ferroptosis-regulating proteins, including NAD(P)H dehydrogenase [quinone] 1 (NQO1) and insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2). Mechanistically, circ-DAPK1 interacts with NQO1, enhancing its ubiquitination and accelerating its degradation. NQO1 overexpression partially rescues HUVECs from high-glucose-induced ferroptosis. We also found that IGF2BP2 binds to the m6A site on circ-DAPK1. Depletion of IGF2BP2 in HUVECs reduced circ-DAPK1 expression and inhibited high-glucose-induced ferroptosis. These findings reveal the effects of the IGF2BP2-circ-DAPK1 axis in regulating ferroptosis in HUVECs under high-glucose conditions and extend our understanding of the mechanisms controlling ferroptosis in endothelial cells.

Autophagy signaling mediated by non-coding RNAs: Impact on breast cancer progression and treatment

Autophagy, a conserved cellular mechanism which detoxifies and degrades intracellular structures or biomolecules, has been identified as an important factor in the progression of human breast cancer and the development of treatment resistance. Non-coding RNAs (ncRNAs), a broad family of RNA, have the ability to influence various processes, including autophagy, due to their diverse downstream targets. ncRNAs play an important role in suppressing or activating autophagy by targeting autophagy-triggering components such as the ULK1 complex, Beclin1, and ATGs. Recent research has uncovered the intricate regulatory networks that govern autophagy dynamics, with ncRNAs emerging as key participants in this network. miRNAs, lncRNAs, and circRNAs are the three subfamilies of ncRNAs that have the most well-known interactions with autophagy, particularly macroautophagy. The high prevalence of breast cancer necessitates research into finding new biological processes that can help in early detection as well as enhance the effectiveness of treatment. The positive/negative link between autophagy and ncRNAs can be exploited as a supplementary therapy to improve sensitivity to treatment in breast cancer. This review investigates the regulatory roles of ncRNAs, particularly microRNAs (miRNAs), in modifying autophagy pathways in human breast cancer progression and treatment. However, future studies and clinical practice are needed to determine the most relevant microRNAs as biomarkers and also to better understand their role in breast cancer progression or treatment through modifying autophagy.

Peripheral Choroid/RPE/Sclera as a Shared Pathogenic Hub: Multi-Tissue Transcriptomic Profiling Identifies Common Differentially Expressed Genes in Age-Related Macular Degeneration and Alzheimer's Disease

BACKGROUND

Age-related macular degeneration (AMD) and Alzheimer's disease (AD), two prevalent neurodegenerative disorders, share overlapping pathophysiological features yet lack cross-disease therapeutic strategies. This study systematically investigates their parallel genes and shared molecular mechanisms to identify potential therapeutic targets for dry AMD, a condition with limited treatment options.

METHODS

Transcriptomic datasets for AMD (GSE155154) and AD (GSE95587) were retrieved from the GEO database. AMD tissues were stratified into four subgroups: macular retina (MR), macular choroid/RPE/sclera (MCRS), peripheral retina (PR), and peripheral choroid/RPE/sclera (PCRS). Common differentially expressed genes (DEGs) were identified and analyzed via functional enrichment (GO, KEGG), gene set enrichment analysis (GSEA), and protein-protein interaction (PPI) networks. Drug-gene interactions and competing endogenous RNA (ceRNA) networks were constructed to prioritize therapeutic targets. Key hub genes were experimentally validated in a sodium iodate-induced AMD murine model using RT-qPCR.

RESULTS

Comparative analysis revealed 89, 56, 4, and 130 common DEGs between AD and MR, MCRS, PR, and PCRS subgroups, respectively. Neuroactive ligand-receptor interactions were prioritized in MR/MCRS-AD analyses, while extracellular matrix organization emerged as the dominant pathway in PCRS-AD comparisons. GSEA identified conserved the TNFα signaling pathway via NF-κB across both diseases. PCRS exhibited consistent expression trends for shared genes and pathways with AD. Computational screening prioritized seven druggable targets (COL1A1, COL1A2, COL3A1, MMP2, MMP9, VCAN, ITGA5) with dual therapeutic potential, along with a reconstructed circRNA (circRNA_002179)-miRNA (miR-124)-mRNA (VCAN) regulatory axis. Experimental validation in a sodium iodate-induced AMD murine model confirmed region-specific dysregulation: hub genes were significantly downregulated in MCRS but upregulated in PCRS.

CONCLUSIONS

Our study delineates both convergent and divergent molecular landscapes of AMD and AD, with PCRS emerging as a critical locus for shared pathophysiology. These findings bridge a critical gap in understanding AMD-AD comorbidity, offering actionable strategies for targeted drug development.

Circ_0006646 Promotes the Progression of Osteoarthritis via Upregulating CDH11 Expression in an IGF2BP2-Dependent Manner

Osteoarthritis (OA) is a common degenerative osteoarthropathy with an unclear pathogenesis. Circular RNA (circRNA) has been reported to be associated with OA progression. This study aims to explore the role and potential mechanism of hsa_circ_0006646 in OA. Interleukin-1β (IL-1β)-induced human chondrocytes were used as the cell model of OA. RT-qPCR and western blotting were used to detect the expression of circ_0006646, IGF2BP2, and cadherin 11 (CDH11). Cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine assay, and flow cytometry were performed to assess chondrocyte cell proliferation and apoptosis, respectively. Western blot assay was performed to determine the levels of proliferation-related proteins, apoptosis-related proteins, and extracellular matrix (ECM) proteins. RNA immunoprecipitation (RIP) assay was performed to verify the interaction between IGF2BP2 and circ_0006646 or CDH11. In OA patients and IL-1β-stimulated chondrocytes, circ_0006646 and CDH11 were upregulated. IL-1β suppressed proliferation and induced apoptosis, inflammation, and ECM degradation in chondrocytes, and circ_0006646 knockdown protected chondrocytes from IL-1β-induced damage. IGF2BP2 was proved to interact with both circ_0006646 and CDH11. The overexpression of IGF2BP2 or CDH11 enhanced IL-1β-induced apoptosis, inflammation, and ECM degradation in chondrocytes. Moreover, circ_0006646 absence-mediated effects in IL-1β-treated chondrocytes could be largely overturned by the overexpression of IGF2BP2 or CDH11. In conclusion, circ_0006646 knockdown protected chondrocytes from IL-1β-induced injury by regulating CDH11 in an IGF2BP2-dependent manner, suggesting a novel potential target for OA treatment.

Decoding microRNA arm switching: a key to evolutionary innovation and gene regulation

miRNA arm switching is a pivotal regulatory mechanism that allows organisms to fine-tune gene expression by selectively utilizing either the 5p or 3p strand of a miRNA duplex. This process, conserved across species, facilitates adaptive responses to developmental cues, environmental changes, and disease states. By dynamically altering strand selection, arm switching reshapes gene regulatory networks, contributing to phenotypic diversity and evolutionary innovation. Despite its growing recognition, the mechanisms driving arm switching-such as thermodynamic properties and enzyme-mediated processing-remain incompletely understood. This review synthesizes current findings, highlighting arm switching as a highly conserved mechanism with profound implications for the evolution of regulatory networks. We explore how this phenomenon expands miRNA functionality, drives phenotypic plasticity, and co-evolves with miRNA gene duplications to fuel the diversification of biological functions across taxa.

circRNA/TLR interaction: key players in immune regulation and autoimmune diseases

Circular RNAs are a class of non-coding RNAs with covalently closed loops. They have been revealed to regulate immune responses by affecting gene expression. Although initially considered splicing byproducts, new studies have indicated their role in transcriptional and post-transcriptional control, especially with TLRs. TLRs start inflammatory signaling and let the innate immune system recognize PAMPs. circRNAs interact context-dependently with TLR pathways to influence immune homeostasis and inflammation in either pathogenic or protective roles. In autoimmune diseases, dysregulated circRNA expression can aggravate immune responses and damage tissue. CircRNAs can interact with RNA-binding proteins, function as molecular sponges for miRNAs, and change inflammatory pathways like the NF-κB signaling cascade, influencing immune responses. They control adaptive immunity, function of antigen-presenting cells, and cytokine generation. The stability and presence of circRNAs in many body fluids make them therapeutic targets and biomarkers for inflammatory and autoimmune diseases. The several immune control roles of circRNA-TLR interactions are discussed in this review, as well as their consequences for immunologically mediated disease diagnosis and treatment.

Developmental Regulation of circRNAs in Normal and Diseased Mammary Gland: A Focus on circRNA-miRNA Networks

Circular RNAs (circRNAs) have emerged as critical regulators in various biological processes including diseases. In the mammary gland (MG), which undergoes most of its development postnatally, circRNAs play pivotal roles in both physiological and pathological contexts. This review highlights the involvement of circRNAs during key developmental stages of the MG, with particular emphasis on lactation, where circRNA-miRNA networks significantly influence milk secretion and composition. CircRNAs exhibit stage-, breed- and species-specific expression patterns during lactation, which underscores their complexity. This intricate regulation also plays a significant role in pathological conditions of the MG, where dysregulated circRNA expression contributes to disease progression such as mastitis, early breast cancer (BC) stages, and epithelial-to-mesenchymal transition in BC (EMT). In mastitis, altered circRNA expression disrupts immune responses and compromises epithelial integrity. During early BC progression, circRNAs drive cell proliferation, while in EMT, they facilitate metastatic processes. By focusing on the circRNA-miRNA interactions underlying these processes, this review highlights their potential use as biomarkers for MG development, disease progression, and as therapeutic targets.

miR-200b-3p affects the proliferation and differentiation of chicken preadipocytes by modulating SESN1 expression through competition with CircADGRF5

Excessive deposition of abdominal fat in chickens has a significant impact on the poultry industry, and there is increasing evidence that non-coding RNAs play a crucial role in fat development. In our previous RNA-seq study, miR-200b-3p was found to be differentially expressed during different developmental periods of fat in Gushi chickens. In this study, we report that miR-200b-3p can directly bind to the 3'UTR region of SESN1 to promote proliferation and inhibit differentiation of preadipocytes. Overexpression of SESN1 inhibits preadipocyte proliferation and promotes differentiation. In contrast, inhibition of SESN1 resulted in the opposite outcome. Interestingly, we also identified the circADGRF5/miR-200b-3p/SESN1 ceRNA network involved in the developmental process of preadipocytes. Furthermore, we validated a novel circRNA, circADGRF5, in this report and found that it regulates SESN1 expression through competitive binding with miR-200b-3p. In conclusion, these data suggest that miR-200b-3p directly targets SESN1 to regulate the proliferation and differentiation of preadipocytes, and circADGRF5 regulates SESN1 expression through competitive binding with miR-200b-3p.

Circ_0001715 Mediated Progression and Inflammation in Fibroblast-Like Synoviocytes of Rheumatoid Arthritis by Targeting miR-326/TLR-4-NF-κB Pathway

Rheumatoid arthritis (RA) is a systemic autoimmune disease. Circular RNA_0001715 (circ_0001715) has been demonstrated to be involved in the progression of cancers. This study aimed to discuss the function of circ_0001715 on the development of RA. Tumor necrosis factor-α (TNF-α) was used to active human RA fibroblast-like synoviocytes (FLS) (HFLS-RA) cells. The role of circ_0001715 in the progression of RA was determined by cell counting kit-8, flow cytometry, enzyme-linked immunosorbent assay. The target of circ_0001715 was predicted using the circinteractome database and validated by the luciferase reporter assay. The relative protein expression of toll-like receptor (TLR)-4/nuclear factor-kappa B (NF-κB) axis was detected by western blot. Moreover, a collagen-induced arthritis (CIA) mouse model was constructed through the secondary immunization. The role of circ_0001715 in vivo was determined by hematoxylin and eosin (H&E), Safranin O, TRAP, ELISA and western blot. Increased levels of circ_0001715 were discovered in tissues from RA patients, TNF-α-induced HFLS-RA cells, and synovial tissues of CIA-induced mice. Knockdown of circ_0001715 decreased proliferation and inflammation, but promoted apoptosis of RA both in vitro and in vivo. Additionally, miR-326 was predicted as the target of circ_0001715, which was confirmed by the luciferase reporter assay. Knockdown of miR-326 reversed the results of proliferation, apoptosis and inflammation resulted from the circ_0001715 knockdown. Mechanically, knockdown of circ_0001715 reduced the expression of TLR-4/NF-κB axis, which were rescued by the downregulation of miR-326. Circ_0001715 sequestered miR-326 to regulate the growth, apoptosis and inflammation of HFLS-RA cells via TLR-4/NF-κB axis.

CircPAFAH1B2 induces chondrocytes mitochondrial dysfunction and promotes cartilage degeneration through binding molecular chaperone ClpB

INTRODUCTION

This study explores the role of circPAFAH1B2 in osteoarthritis (OA) by investigating its influence on nuclear-mitochondrial communication, a largely unexplored area in OA progression. By uncovering how circPAFAH1B2 regulates mitochondrial function, the study aims to identify novel therapeutic targets for OA prevention and treatment.

OBJECTIVES

This study aimed to identify the regulatory role of circPAFAH1B2 in nuclear-mitochondrial communication within chondrocytes and cartilage homeostasis.

METHODS

circPAFAH1B2 expression was determined via quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. RNA pulldown experiments, proteomic analyses, and RNA immunoprecipitation were conducted to identify the downstream targets of circPAFAH1B2. Gain- and loss-of-function assays were performed to evaluate the regulatory roles of circPAFAH1B2 and the molecular chaperone caseinolytic peptidase B protein homolog (ClpB) in mitochondrial function and chondrocyte homeostasis in cartilage. Cross-linking immunoprecipitation and sequencing were performed to identify binding sites between circPAFAH1B2 and ClpB.

RESULTS

circPAFAH1B2 was upregulated in OA and localized to the cytoplasm of chondrocytes. In vivo and in vitro experiments demonstrated that increased levels of circPAFAH1B2 induced mitochondrial dysfunction and promoted cartilage degeneration. Mechanistic investigations revealed that circPAFAH1B2 bound to and restricted the mitochondrial import of the molecular chaperone ClpB, which disaggregates misfolded mitochondrial proteins, stabilizes mitochondrial homeostasis, and maintains chondrocyte homeostasis. We characterized the binding sites of circPAFAH1B2 and ClpB, and demonstrated that mutation of these sites effectively suppressed circPAFAH1B2-mediated OA phenotypes.

CONCLUSIONS

Our findings indicate that circPAFAH1B2 acts as a molecular decoy blocking ClpB mitochondrial translocation, driving mitochondria-dependent cartilage degradation, which may provide novel therapeutic targets for OA.

Frequent dysregulation of multiple circular RNA isoforms with diverse regulatory mechanisms in cancer - Insights from circFNDC3B and beyond: Why unique circular RNA identifiers matter

Circular RNAs (circRNAs) are post-transcriptional regulators generated through backsplicing of pre-mRNAs, primarily comprising exons of host genes. A single host gene may produce multiple circRNA isoforms with distinct structures and sequences. Dysregulated circRNA expression has been implicated in tumorigenesis. This review aims to investigate the selection and regulatory roles of circRNA isoforms in cancer using the extensively studied hsa_circFNDC3B and thirteen other circRNAs as study models. Interrogation of literature and databases, particularly the circBase, confirms that host genes generate a plethora of circRNA isoforms; however, only a small subset of isoforms is validated as dysregulated in tumor tissues. Notably, two or more isoforms of the same circRNA are frequently dysregulated in cancer. Structurally, short isoforms retaining 5'-proximal exons are preferentially selected, but for long host genes, circRNAs may arise from mid- or 3'-regions. We identify dysregulation of seven circFNDC3B isoforms across twelve cancer types and multi-isoforms in nine of the other thirteen circRNAs also in multiple cancers. MicroRNA sponging appears to be the major regulatory mechanism, but possible biased study designs raise concerns. Using circFNDC3B and circZFR as examples, we show inconsistency and inadequacy in circRNA nomenclature in different databases and the literature, underscoring the urgent need for a universally accepted standardized central circRNA database. As an interim measure, we propose guidelines for circRNA nomenclature in journal publications. Our findings caution against indiscriminate clinical use of specific circRNA isoforms as biomarkers or therapeutic targets without further validation.

Plasmodium Infection Modulates Host Inflammatory Response through circRNAs during the Intracellular Stage in Red Blood Cells

The integration of RNA- and DNA-based assays enables the investigation of disease dynamics, specifically assessing the role of asymptomatic or subclinical infections in malaria transmission. Circular RNAs (circRNAs), a distinct category of noncoding RNAs, are implicated in numerous pathogenic mechanisms. As of now, research has yet to explore circRNAs' function in malaria infection. The findings revealed that Plasmodium infection upregulated 60 circRNAs and downregulated 71 in BALB/c mice. We selected 11 differentially expressed (DE) circRNAs according to function prediction of target miRNA-mRNA and coding protein, and these were further confirmed by validation experiments. IRESfinder, GO, and KEGG evaluations indicated that 7 DE circRNAs possess protein-coding potential and are enriched in the MAPK signaling cascade. In P.y17XL-infected BALB/c mouse models, the findings substantiated that the dynamic characteristics of DE circRNAs correlated with inflammation, and the MAPK and NF-κB signaling cascades were activated, also contributing to the inflammatory reaction during malaria infection. This study establishes Plasmodium-induced circRNA expression as a novel mechanism by which the parasite modulates host immune signaling, advancing the understanding of Plasmodium-host cell interactions. In addition, 42 circRNAs were found in normal BALB/c mice, and 25 circRNAs were discovered in P.y17XL-infected BALB/c mice, excluding 1238 circRNAs shared by normal and P.y17XL-infected BALB/c mice. Plasmodium infection changes the expression profile of circRNAs in the host, and these altered circRNAs are involved in the inflammatory response during malaria infection. In addition, Plasmodium possibly regulates the reverse splicing of pre-mRNA or m6A modification of RNA, inducing the production of novel circRNAs in the host.

Construction of a circRNA-miRNA-mRNA Regulatory Network for the Immune Regulation of Lung Adenocarcinoma

BACKGROUND

Recent research has highlighted the significance of circular RNAs (circRNAs) as pivotal regulators in the progression of tumors and the therapeutic response in non-small cell lung cancer (NSCLC). These circRNAs function through a sponge mechanism, interacting with microRNAs (miRNAs) to modulate mRNA expression levels. Nevertheless, the precise role of the circRNA-miRNA-mRNA regulatory network in immune regulation within lung adenocarcinoma (LUAD) remains inadequately understood.

METHODS AND MATERIALS

We utilized microarray datasets from the GEO NCBI database (GSE101586) to identify differentially expressed circRNAs (DEcircRNAs) in LUAD. CircBank was employed to predict the target miRNAs of DEcircRNAs, which were subsequently intersected with miRNAs from the GSE36681 database. The identified miRNAs were then predicted to target mRNAs using miRDB and miWalk, and intersections with immune-related genes from the IMMPORT database were analyzed. Protein-protein interaction (PPI) networks were constructed using Cytoscape software. The DAVID functional annotation tool was utilized to explore potential biological processes, molecular functions, and KEGG pathways associated with LUAD. Gene expression and Kaplan-Meier survival analyses were conducted to establish a key regulatory network and to assess immune cell infiltration and Pearson correlation for significant target genes. Finally, we selected the most significantly upregulated circRNA with differential expression for validation through in vitro experiments.

RESULTS

Our analysis identified a total of 7 upregulated and 42 downregulated circRNAs, along with 10 significant miRNAs and 20 target mRNAs. KEGG enrichment analysis indicated that these components are primarily enriched in the ErbB signaling pathway. Furthermore, Gene Ontology (GO) analysis revealed significant enrichment in responses to organic substances, cytokine-mediated signaling pathways, cellular responses to cytokines, responses to chemical stimuli, steroid hormone receptor activity, ErbB-3 class receptor binding, oxysterol binding, signal receptor activity, and molecular transducer activity. Notable core mRNAs identified included OAS1, VIPR1, and PIK3R1. Subsequently, we constructed a regulatory network comprising 6 DEcircRNAs, 3 DEmiRNAs, and 3 DEmRNAs. Through ssGSEA and CIBERSORT analyses, we observed significant differences in immune cell infiltration levels between the NSCLC cohort and the control group. Knocking down the expression of hsa_circ_0079557 significantly inhibited the viability, proliferation, migration, and invasion of LUAD cells.

CONCLUSION

We have established a circRNA-miRNA-mRNA regulatory network that offers novel insights into the molecular mechanisms governing immune regulation in LUAD. Future research should aim to translate these findings into clinical applications to enhance patient outcomes.

Circ_0035381 contributes to the progression of acute myeloid leukemia via regulating miR-186-5p/CDCA3 pathway

BACKGROUND

Circular RNAs (circRNAs) are involved in acute myeloid leukemia (AML) and may be useful for AML therapy. Herein, the project aimed to explore the functions and mechanisms of circ_0035381 in AML.

RESEARCH DESIGN AND METHODS

Circ_0035381, microRNA-186-5p (miR-186-5p), and cell division cycle associated 3 (CDCA3) expression were determined using quantitative real-time polymerase chain reaction (qRT-PCR) assay. Western blot assay was used to measure protein levels. 5'-ethynyl-2'-deoxyuridine (EdU) and flow cytometry were adopted to measure cell proliferation and apoptosis. Glucose consumption and lactate uptake were examined with commercial kits. The relationships between miR-186-5p and circ_0035381 or CDCA3 were validated using dual-luciferase reporter and RNA pull-down assays.

RESULTS

Circ_0035381 was increased in the AML subject and AML cell line. Circ_0035381 deficiency hindered the proliferation and glycolysis level and promoted apoptosis in the AML cell line. Circ_0035381 sponged miR-186-5p and miR-186-5p inhibition reversed the effect of circ_0035381 knockdown on AML cell progression. CDCA3 was the target gene of miR-186-5p. CDCA3 overexpression reversed circ_0035381 knockdown-mediated AML cell proliferation and glycolysis inhibition and apoptosis promotion.

CONCLUSIONS

Circ_0035381 promoted AML progression by elevating CDCA3 through sponging miR-186-5p, providing some clues for the diagnosis and treatment of AML.

Expression level and clinical significance of NEAT1 in patients with chronic periodontitis

Background/purpose

Previous studies have shown that lncRNA nuclear autosomal transcript 1 (NEAT1) is abnormally expressed in periodontitis patients. However, the pathological mechanism of NEAT1 regulating periodontitis is still not clear. This study attempted to explore the expression of NEAT1 in periodontitis patients and its effect on periodontitis cell model and inflammatory response.

Materials and methods

The expressions of NEAT1 and miR-205-5p in gingival crevicular fluid (GCF) and cell samples were analyzed by qRT-PCR. The diagnostic value of NEAT1 in periodontitis was evaluated by constructing an ROC curve. The efficacy of NEAT1 on cell function and inflammatory response were assessed in LPS-induced PDLSCs. Luciferase reporter gene assay verified the targeting relationship between miR-205-5p and NEAT1.

Results

In the clinical section of this study, it was observed that NEAT1 expression was increased in GCF of periodontitis patients, and NEAT1 was found to be useful for periodontitis diagnosis. Besides, in vitro experiments suggested that inhibition of NEAT1 could improve cell viability and attenuated cell apoptosis and generation of inflammatory factors. Subsequently, luciferase reporter gene assay revealed that miR-205-5p was the target gene of NEAT1, and was negatively regulated by NEAT1.

Conclusion

High expression of NEAT1 has diagnostic value for periodontitis, and NEAT1 knockdown may reduce LPS-induced cell damage by increasing the level of miR-205-5p, which may provide a new breakthrough for the diagnosis and treatment of periodontitis.

Regulatory effect and mechanism of CircSEC24A in IL-1β-induced osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by articular cartilage degeneration and damage. Increasing circular RNAs (circRNAs) have been identified to participate in the pathogenesis of OA. Hsa_circ_0128006 (also known as circSEC24) was reported as an upregulated circRNA in OA tissues, but its biological role and underlying mechanism in OA are still to be discussed. circSEC24A and NAMPT expression levels were upregulated, and miR-515-5p was reduced in OA cartilage tissues and IL-1β-treated CHON-001 cells. The absence of circSEC24A overturned IL-1β-induced suppression of cell viability and promotion of oxidative stress, apoptosis, extracellular matrix (ECM) degradation, and inflammation in CHON-001 cells. Mechanistically, circSEC24A acted as a molecular sponge for miR-515-5p to affect NAMPT expression. CircSEC24A knockdown could attenuate IL-1β-triggered CHON-001 cell injury partly via the miR-515-5p/NAMPT axis, providing new insight into the underlying application of circSEC24A in OA treatment.

Circular RNA in liver cancer research: biogenesis, functions, and roles

Liver cancer, characterized by its insidious nature, aggressive invasiveness, and propensity for metastasis, has witnessed a sustained increase in both incidence and mortality rates in recent years, underscoring the urgent need for innovative diagnostic and therapeutic approaches. Emerging research indicates that CircRNAs (circular RNAs) are abundantly and stably present within cells, with their expression levels closely associated with the progression of various malignancies, including hepatocellular carcinoma. In the context of liver cancer progression, circRNAs exhibit promising potential as highly sensitive diagnostic biomarkers, offering novel avenues for early detection, and also function as pivotal regulatory factors within the carcinogenic process. This study endeavors to elucidate the biogenesis, functional roles, and underlying mechanisms of circRNAs in hepatocellular carcinoma, thereby providing a fresh perspective on the pathogenesis of liver cancer and laying a robust foundation for the development of more precise and effective early diagnostic tools and therapeutic strategies.

The Application of Non-Coding RNAs as Biomarkers, Therapies, and Novel Vaccines in Diseases

Non-coding RNAs (ncRNAs) are a class of RNAs that largely lack the capacity to encode proteins. They have garnered significant attention due to their central regulatory functions across numerous cellular and physiological processes at transcriptional, post-transcriptional, and translational levels. Over the past decade, ncRNA-based therapies have gained considerable attention in the diagnosis, treatment, and prevention of diseases, and many studies have revealed a significant relationship between ncRNAs and diseases. At the same time, due to their tissue specificity, an increasing number of projects have focused on the application of ncRNAs as biomarkers in diseases, as well as the design and development of novel ncRNA-based vaccines and therapies for clinical use. These ncRNAs may also drive research into the potential molecular mechanisms and complex pathogenesis of related diseases. However, new biomarkers need to be validated for their clinical effectiveness. Additionally, to produce safe and stable RNA products, factors such as purity, precise dosage, and effective delivery methods must be ensured to achieve optimal bioactivity. These challenges remain key issues in the clinical application of ncRNAs. This review summarizes the prospects of ncRNAs as potential biomarkers, as well as the current research status and clinical applications of ncRNAs in therapies and vaccines, and discusses the challenges and expectations of ncRNAs in disease diagnosis and drug therapy.

Discovery of circular transcripts of the human BCL2-like 12 (BCL2L12) apoptosis-related gene, using targeted nanopore sequencing, provides new insights into circular RNA biology

Circular RNAs (circRNAs) constitute an RNA type formed by back-splicing. BCL2-like 12 (BCL2L12) is an apoptosis-related gene comprising 7 exons. In this study, we used targeted nanopore sequencing to identify circular BCL2L12 transcripts in human colorectal cancer cells and investigated the effect of circRNA silencing on mRNA expression of the parental gene. In brief, nanopore sequencing following nested PCR amplification of cDNAs of BCL2L12 circRNAs from 7 colorectal cancer cell lines unraveled 46 BCL2L12 circRNAs, most of which described for the first time. Interestingly, 40 novel circRNAs are likely to form via back-splicing between non-canonical back-splice sites residing in highly similar regions of the primary transcripts. All back-splice junctions were validated using next-generation sequencing (NGS) after circRNA enrichment. Surprisingly, 2 novel circRNAs also comprised a poly(A) tract after BCL2L12 exon 7; this poly(A) tract was back-spliced to exon 1, in both cases. Furthermore, the selective silencing of a BCL2L12 circRNA resulted in a subsequent decrease of BCL2L12 mRNA levels in HCT 116 cells, thus providing evidence of parental gene expression regulation by circRNAs. In conclusion, our study led to the discovery of many circular transcripts from a single human gene and provided new insights into circRNA biogenesis and mode of action.

Hsa_circ_0006006 is a potential biomarker for prognosis and cisplatin resistance in non-small cell lung cancer

BACKGROUND AND OBJECTIVE

Platinum-based drugs, such as cisplatin (DDP), are the standard treatment, yet drug resistance has become a key challenge. Previous studies have shown that hsa_circ_0006006 promotes non small cell lung cancer (NSCLC) progression. This study aimed to reveal the role of specific circRNAs in DDP resistance in NSCLC and their potential clinical applications.

METHODS

CircRNA sequencing data of three NSCLC tissue and three normal tissue samples were extracted from the GEO database based on conditions that matched the microarray expression profiles of circRNAs from human NSCLC lung samples and matched neighboring samples and raw matrix data and platform annotation data, and differential expression analysis was performed using the R language. Log2 Fold change > 1 and P < 0.05 were labeled as differential genes. Serum samples were collected from 31 NSCLC patients and 21 DDP-resistant NSCLC patients. The Kaplan-Meier method was used to detect the correlation between circRNA levels and survival prognosis of NSCLC patients. The relationship between circRNAs and clinicopathological characteristics of patients was assessed by chi-square test. RT-qPCR was performed to detect the expression of key circRNAs associated with DDP drug resistance. circRNAs were analyzed by ROC curves to assess the diagnostic potential. A549 cells and A549/DDP cells were cultured to verify the effect of up- and down-regulation of hsa_circ_0006006 on DDP drug resistance in NSCLC cells using colony formation assay and flow cytometry.

RESULTS

Abnormally elevated hsa_circ_0006006 expression was closely associated with NSCLC survival prognosis as well as DDP resistance (p < 0.05) with good diagnostic efficacy (AUC for NSCLC = 0.91, p < 0.01; AUC for DDP resistant = 0.80, p = 0.00). This was further validated in the analysis of clinical samples (p < 0.05). Knockdown of hsa_circ_0006006 significantly reduced DDP resistance in NSCLC cells, while overexpression of hsa_circ_0006006 had the opposite effect (p < 0.05).

CONCLUSION

NSCLC survival prognosis is associated with aberrant expression of hsa_circ_0006006, which regulates NSCLC cell proliferation and apoptosis and thus promotes DDP drug resistance. These findings provide potential targets for patient prognosis and assessment of biomarkers of response to DDP therapies that can be used to aid in early diagnosis and prognostic assessment, as well as new options for the future development of relevant small-molecule inhibitors or nucleic acid drugs.

Mechanistic insights into Jianpi Qinghua Sanyu Yin treatment of raised erosive gastritis: ceRNA-mediated PI3K/AKT signaling pathways

Background

Raised erosive gastritis (REG) is a chronic gastritis with a high risk of malignant transformation. Current treatments often result in high recurrence rates and complications. Jianpi Qinghua Sanyu Yin (JPQHSYY), a traditional Chinese medicine, shows promise in treating REG. However, the underlying molecular mechanisms remain unclear. This study aimed to investigate the potential mechanism of JPQHSYY's therapeutic effects on REG.

Methods

RNA-seq was employed to systematically analyze mRNA, lncRNA, and miRNA profiles in gastric mucosal tissues from REG patients before and after JPQHSYY treatment. The pivotal lncRNA-miRNA and miRNA-mRNA networks were predicted from sequencing data and bioinformatic analysis, and the results were exported using Cytoscape software. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used for functional exploration. Real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to validate RNA-seq analysis results. CCK8, cell cycle, apoptosis and western blot were performed to detect the effects of miR-122-5p in GES-1 cells in vitro.

Results

RNA-seq analysis revealed 576 differentially expressed lncRNAs (269 upregulated, 307 downregulated), 33 differentially expressed miRNAs (13 upregulated, 20 downregulated), and 1717 differentially expressed mRNAs (777 upregulated, 940 downregulated) in JPQHSYY-treated REG patients. GO and KEGG analyses highlighted key pathways, including the PI3K/AKT signaling pathway, involved in cell cycle and apoptosis regulation. The ceRNA network analysis suggested that JPQHSYY impacts the miRNA-lncRNA interactions. Validation experiments confirmed that JPQHSYY inhibits the PI3K/AKT pathway, reducing cell viability, colony formation, and promoting apoptosis in miR-122-5p transfected GES-1 cells.

Conclusion

The therapeutic efficacy of JPQHSYY in treating REG might be mediated by the ceRNA-driven PI3K/AKT pathway signaling pathways, which is implicated in the proliferation of gastric mucosal epithelial cells. Furthermore, the investigation of miRNA-lncRNA networks could reveal more information on potential new mechanisms and targets for JPQHSYY in the management of REG.

Structures of a natural circularly permuted group II intron reveal mechanisms of branching and backsplicing

Circularly permuted (CP) group II introns, identified in various bacteria phyla, swap domains D5 and D6 near the 5' end and have reversed splice sites (SSs), leading to backsplicing and circular RNA formation. In this study, we present multiple high-resolution cryo-electron microscopy structures of a natural CP group II intron from Comamonas testosteroni KF-1 (Cte 1), elucidating the molecular mechanisms of branching and backsplicing. During branching, the 5' SS is positioned by an auxiliary sequence (AUX)-enhanced interaction between the exon-binding site and intron-binding site (IBS) and stacks on the branch-site adenosine within D6, allowing the attacking 2'-OH group to coordinate with a metal ion in the active center. In backsplicing, the 3' SS is aligned with the branching step, leaving IBS in the active center, stabilized by base pairing with the AUX, which enables the free 3'-end hydroxyl group to directly attack the scissile phosphate of 3' SS. Furthermore, a groove in Cte 1 may stabilize the circular RNA. These findings highlight a conserved catalytic mechanism for canonical group II introns, albeit facilitated by the versatile AUX, opening avenues for designing potent ribozymes producing circular RNAs.

Co-modulation of a circular form of PCDH11Y during neuroendocrine differentiation of prostate cancer

Introduction

Prostate cancer (PC) is a leading cause of cancer-related deaths among men, often progressing to castration-resistant prostate cancer (CRPC) after androgen deprivation therapy (ADT). A subset of CRPC evolves into treatment-emergent neuroendocrine prostate cancer (t-NEPC), an aggressive form characterized by poor prognosis. Currently, there is no reliable biomarker for early detection of t-NEPC. Circular RNAs (circRNAs) have emerged as potential biomarkers due to their stability and tissue-specific expression.

Methods

In this study, we investigated the circRNA landscape during neuroendocrine transdifferentiation (NED) of PC cells using the androgen-sensitive LNCaP and androgen-insensitive DU145 cell lines. To achieve that, we applied CirComPara2 pipeline to publicly available datasets to identify the differently expressed circRNAs in the LNCaP cell lines pre- and post-transdifferentiation. After that, validation and functional analysis by RNA-interference was applied to a selected circRNA to explore its role during NED.

Results

We identified over 6,200 circRNAs, of which 33 were differentially expressed during NED. Among them, a novel circRNA, circPCDH11Y, was highly upregulated during the transition of LNCaP cells from an epithelial to neuroendocrine phenotype, while its levels remained unchanged in DU145 cells. Functional assays demonstrated that circPCDH11Y plays a role in regulating the expression of key neuroendocrine markers, including synaptophysin (SYP), neuron-specific enolase (ENO2), prostate-specific antigen (PSA), Brain-Specific Homeobox/POU Domain Protein 2 (BRN2) and the linear form of Protocadherin 11 Y-Linked (PCDH11Y). Silencing circPCDH11Y delayed the expression of SYP, ENO2 and PCDH11Y, while increasing PSA and BRN2 transcriptional levels, indicating its involvement in promoting neuroendocrine differentiation. Additionally, circPCDH11Y was detected in extracellular vesicles (EVs) secreted by LNCaP cells post-NED, suggesting its potential as a circulating biomarker.

Discussion

These findings highlight circPCDH11Y as a promising candidate for early detection of t-NEPC and provide new insights into the molecular mechanisms underlying prostate cancer progression. Further validation in clinical samples is required to establish its diagnostic and therapeutic potential, which could significantly improve the management of treatment-resistant prostate cancer.

CircRNA-miRNA-mRNA interactome analysis in endometrial cancer

In recent years, exploring the potential of miRNAs as novel diagnostic, prognostic and diagnostic markers have gained much attention. In current study, we conducted an in-depth circRNA-miRNA-mRNA interactome to reveal significant molecular processes and biological pathways putatively associated with endometrial cancer (EC). Firstly, we retrieved two circRNAs from circad, hsa_circ_0002577 & hsa_circ_0109046, based on their association with the EC. Subsequently, we predicted miRNAs sponging sites in the two circRNAs and the potential target mRNAs of the predicted miRNAs. Sequestered miRNAs target a number of oncogenes (CBL, MET, KRAS), tumor suppressor (CFT R), receptor protein kinases & GT Pase (MET, KRAS, RAB1B), methyltransferases (SET D8), receptors associated factors (T RAF2, GRB2), growth factors (FGF20), autophagy (BECN1, AT G14), apoptotic regulators (BCL2), transcription factors (T Fs) (CREB1, RUNX1, RUNX2) and gene regulators (CCND1, HIF1A); and others, including some novel gene candidates (CREB1, FGF20, IFI27), that have never been implicated in EC earlier. The expression of hsa-miR-433-3p showed significant predictive relevance (Fold Change = 1.8, AUC = 0.736, Mann-Whitney test p-value = 6.1 e- 14) suggesting its predictive relevance in assessing patients' response to chemotherapy. The hsamiR- 188-3p targets autophagic and apoptotic regulators and its upregulation in endometriosis may be used as for the early stage diagnostic purpose. The hsa-miR-502-5p targets SET D8, T RAF2 and others and suggests additional genomic/epigenomic molecular targets for promising therapeutic interventions in EC. Predicted miRNAs target a number of mRNAs having varied functional impacts and offer an in-depth mechanistic insights for expatiating the biological and regulatory role in EC.Communicated by Ramaswamy H. Sarma.

Circ_BLNK is a Unique Molecular Marker in Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) patients are characterized by distant metastasis and poor prognosis. Growing evidence has implied that circular RNAs (circRNAs) are involved in multiple tumor progression, including NSCLC. The objective of the present study was to functionally dissect the role and mechanism of circ_BLNK in NSCLC development and progression. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expression of circ_BLNK, miR-942-5p, and forkhead box protein O1 (FOXO1) in NSCLC tissues and cells. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay and colony formation assay detected cell proliferation; the protein expression levels were tested by western blot assay; cell apoptosis was measured by flow cytometry, and transwell assay detected cell migration and invasion. The molecular targeting relationship was determined by dual-luciferase reporter assay. The effect of circ_BLNK overexpression on tumor growth was detected by in vivo experiments and immunohistochemistry. Circ_BLNK was dramatically decreased in NSCLC, and overexpression of circ_BLNK inhibited proliferation, migration, and invasion of NSCLC cells and promoted cell apoptosis. Circ_BLNK level was negatively correlated with miR-942-5p expression and positively correlated with FOXO1 expression. Moreover, circ_BLNK acted as a sponge for miR-942-5p, which targeted FOXO1. Rescue assays presented that miR-942-5p reversed the anticancer action of circ_BLNK in NSCLC. Besides that, miR-942-5p inhibition suppressed the oncogenic behaviors, which were attenuated by FOXO1 knockdown. Animal experiments exhibited that circ_BLNK upregulation repressed tumor growth in vivo. Our study demonstrated a novel regulatory mechanism that circ_BLNK/miR-942-5p/FOXO1 axis adjusted non-small cell lung cancer development.

Circular RNA-Cacna1d Plays a Critical Role in Sepsis-induced Lung Injury by Sponging microRNA-185-5p

The role of circular RNAs (circRNAs) in sepsis-induced lung injury is not clear. This study investigated the role and molecular mechanism of a novel circRNA in sepsis-induced lung injury and explored its prognostic value in patients with sepsis. In this study, aberrant circRNA expression profiling in lung tissues from mice with sepsis-induced lung injury was analyzed using high-throughput sequencing. circRNA-Cacna1d was verified by qRT-PCR, and its biological function in sepsis-induced lung injury was validated in vitro and in vivo. The interactions among circRNA-Cacna1d, microRNAs (miRNAs), and their downstream genes were verified. Furthermore, the clinical value of circRNA-Cacna1d in peripheral blood from patients with sepsis was also evaluated. We found that circRNA-Cacna1d expression was significantly increased in lung tissues of mice with sepsis and in microvascular endothelial cells after LPS challenge. circRNA-Cacna1d knockdown alleviated inflammatory response and ameliorated the permeability of vascular endothelium, thereby mitigating sepsis-induced lung injury and significantly improving the survival rate of mice with sepsis. Mechanistically, circRNA-Cacna1d directly interacted with miRNA-185-5p and functioned as a miRNA sponge to regulate the RhoA/ROCK1 signaling pathway. The expression level of circRNA-Cacna1d in patients with early sepsis was significantly higher than that in the healthy control subjects. Higher levels of circRNA-Cacna1d in patients with sepsis were associated with increased disease severity and poorer outcomes. In conclusions, circRNA-Cacna1d may play a role in sepsis-induced lung injury by regulating the RhoA/ROCK1 axis by acting as a miRNA-185-5p sponge. circRNA-Cacna1d is a potential therapeutic target for sepsis-induced lung injury and a prognostic biomarker in sepsis.

Hsa_circ_0009910 knockdown in HeLa cells increases miR‑198 expression levels and decreases c‑Met expression levels and cell viability

Cervical cancer (CC) is considered a public health problem. Circular RNAs (circRNAs) serve important roles in different types of cancer, including CC. However, the mechanisms used by circRNAs to facilitate CC progression are currently unclear. The present study analyzed the effects of hsa_circ_0009910 knockdown on microRNA (miRNA/miR)-198 and mesenchymal-epithelial transition factor (c-Met) expression levels and its impact on apoptosis and the viability of HeLa cells. Differentially expressed circRNAs in CC were identified using analysis of circRNA microarray data. Bioinformatics analysis was performed to predict circRNA-microRNA (miRNA) and miRNA-mRNA interactions. The knockdown of hsa_circ_0009910 in HeLa cells was performed using small interfering RNA and the expression levels of hsa_circ_0009910, miR-198 and c-Met were assessed using reverse transcription-quantitative PCR. The viability and apoptosis of HeLa cells were evaluated using MTT, neutral red uptake and ApoLive-Glo™ multiplex assays. Hsa_circ_0009910 was significantly upregulated in HeLa cells and the knockdown of hsa_circ_0009910 increased miRNA-198 expression levels, reduced c-Met expression levels and decreased cellular viability, but not apoptosis, in HeLa cells. Overall, these results indicated that hsa_circ_0009910 could act as a molecular sponge of miRNA-198 and contribute to the upregulation of c-Met expression levels. The hsa_circ_0009910/miRNA-198/c-Met interaction network affects the viability, but not apoptosis, of HeLa cells. Based on this mechanism, the present study suggests that hsa_circ_0009910 may be a promising biomarker for CC.

hsa_circ_0000129 targets miR-383-5p/tropomyosin 3 axis to facilitate ovarian cancer progression

Ovarian cancer is one of the most prevalent malignancies among women. CircRNAs play key roles in the progression of ovarian cancer. This study aimed to investigate the mechanism of action of hsa_circ_0000129 and its effects on ovarian cancer. Expression of hsa_circ_0000129, tropomyosin 3 (TPM3), and miR-383-5p in ovarian cancer cell lines and tissue specimens was detected using qRT-PCR or western blotting. Cell counting kit-8 (CCK-8), colony formation, and transwell assays were performed to assess viability, proliferation, and migration of ovarian cancer cells. A xenograft model was used to study tumorigenicity of ovarian cancer cells in vivo. Luciferase and RNA immunoprecipitation assays were performed to determine binding between miR-383-5p and hsa_circ_0000129 or TPM3. Upregulation of hsa_circ_0000129 and TPM3 and downregulation of miR-383-5p were observed in ovarian cancer. Low hsa_circ_0000129 and TPM3 expression repressed viability, migration, and proliferation of ovarian cancer cells. Inhibition of miR-383-5p had a contrary effect. Furthermore, knockdown of hsa_circ_0000129 restricted the tumorigenicity of ovarian cancer cells. Mechanistically, hsa_circ_0000129 has a sponging effect on miR-383-5p, which targets TPM3. Hsa_circ_0000129 stimulated development of the malignant ovarian cancer phenotype by sponging miR-383-5p and releasing TPM3.

Overexpression of Circ-Astn1 Suppresses Hyperglycemia-Induced Endothelial Cell Damage via the miR-138-5p/SIRT1 Axis

OBJECTIVE

To elucidate the regulatory mechanism of circRNAs in diabetic retinopathy.

METHODS

Next-generation sequencing (NGS) was employed to identify circRNAs that are abnormally expressed in endothelial progenitor cells (EPCs) under hyperglycemia (HG) conditions. The regulatory mechanism and predicted targets of this circRNA were also studied via bioinformatics analysis, luciferase reporter assays, angiogenic differentiation experiments, flow cytometry, and RT-qPCR.

RESULTS

Circ-astrotactin 1 (circ-Astn1) expression was decreased in EPCs under HG conditions, and circ-Astn1 overexpression inhibited HG-induced endothelial damage. The miR-138-5p and silencing information regulator 2 related enzyme 1 (SIRT1) were identified as circ-Astn1 downstream targets, which were further verified through luciferase reporter assays. SIRT1 silencing or miR-138-5p overexpression reversed the protective effect of circ-Astn1 on HG-induced endothelial cell dysfunction, as evidenced by increased apoptosis, abnormal vascular differentiation, and inflammatory factor secretion. SIRT1 overexpression reversed miR-138-5p-induced endothelial cell dysfunction under HG conditions. In vivo experiments confirmed that circ-Astn1 overexpression promoted skin wound healing through the regulation of SIRT1.

CONCLUSIONS

These findings suggest that circ-Astn1 promotes SIRT1 expression by sponging miR-138-5p. Circ-Astn1 overexpression suppresses HG-induced endothelial cell damage via miR-138-5p/SIRT1 axis.

Mechanism of hsa_circ_0069443 promoting early pregnancy loss through ALKBH5/FN1 axis in trophoblast cells

Studies have shown that circRNAs play an important regulatory role in trophoblast function and embryonic development. Based on sequencing and functional experiments, we found that hsa_circ_0069443 can regulate the function of trophoblast cells, and its presence is found in the exosomes secreted by trophoblast cells. It is known that exosomes mediate the interaction between the uterus and embryo, which is crucial for successful pregnancy. We found that trophoblast cell-derived exosomes overexpressing hsa_circ_0069443 promoted the migration and invasion of endometrial stromal cells as well as the EMT process of endometrial glandular epithelial cells, and this process promotes embryo implantation and adhesion, thus proving that a decrease in hsa_circ_0069443 may be the key factor leading to early pregnancy loss. This study also found that hsa_circ_0069443 can bind to the RNA-binding protein demethylase ALKBH5, affecting the overall m6A level of trophoblast cells, and hsa_circ_0069443 and ALKBH5 can regulate the expression level of FN1, verifying the role of the 0069443/ALKBH5/FN1 axis in trophoblast cells and endometrial stromal cells. In summary, this study demonstrates that hsa_circ_0069443 may be a key factor leading to early pregnancy loss, and the regulation of the hsa_circ_0069443/ALKBH5/FN1 axis may provide new insights into early diagnostic markers for early pregnancy loss.

Translation of circular RNAs

Circular RNAs (circRNAs) are covalently closed RNAs that are present in all eukaryotes tested. Recent RNA sequencing (RNA-seq) analyses indicate that although generally less abundant than messenger RNAs (mRNAs), over 1.8 million circRNA isoforms exist in humans, much more than the number of currently known mRNA isoforms. Most circRNAs are generated through backsplicing that depends on pre-mRNA structures, which are influenced by intronic elements, for example, primate-specific Alu elements, leading to species-specific circRNAs. CircRNAs are mostly cytosolic, stable and some were shown to influence cells by sequestering miRNAs and RNA-binding proteins. We review the increasing evidence that circRNAs are translated into proteins using several cap-independent translational mechanisms, that include internal ribosomal entry sites, N6-methyladenosine RNA modification, adenosine to inosine RNA editing and interaction with the eIF4A3 component of the exon junction complex. CircRNAs are translated under conditions that favor cap-independent translation, notably in cancer and generate proteins that are shorter than mRNA-encoded proteins, which can acquire new functions relevant in diseases.

Circular RNAs in cancer: roles, mechanisms, and therapeutic potential across colorectal, gastric, liver, and lung carcinomas

The prominence of circular RNAs (circRNAs) has surged in cancer research due to their distinctive properties and impact on cancer development. This review delves into the role of circRNAs in four key cancer types: colorectal cancer (CRC), gastric cancer (GC), liver cancer (HCC), and lung cancer (LUAD). The focus lies on their potential as cancer biomarkers and drug targets. Our study analyses the reported circRNAs in the mentioned malignancies, examining their nature, functions, targets, origins, and contributions as tumor enhancers or suppressors. The approach involved assessing full-text reports on PMC, utilizing keywords such as "CircRNA" and "Cancer types," coupled with bioinformatics, experimental assays, or clinical investigations. Exclusions encompassed non-English publications, conference abstracts, letters, and expert opinions. The findings unveil 577 identified circRNAs across these cancer types: 124 in CRC, 177 in GC, 93 in HCC, and 183 in LUAD. Mechanistic insights into how circRNAs modulate gene expression in cancer are explored, particularly their interactions with microRNAs and RNA-binding proteins. Dysregulation of circRNAs across various cancers and their potential as diagnostic and prognostic indicators are synthesized. The exploration extends to the potential of targeting circRNAs as a novel cancer therapy strategy, either through inhibiting oncogenic circRNAs or reinstating tumor-suppressive ones. This article discusses the challenges and prospects in harnessing circRNAs for cancer diagnostics and therapies. These comprehensive analyses hold promise for advancing cancer research and fostering the development of innovative therapies and diagnostics.

EIF4A3-Induced Circ_0059914 Promoted Angiogenesis and EMT of Glioma via the miR-1249/VEGFA Pathway

Gliomas are common brain tumors. Despite extensive research, the 5-year survival rate of glioma remains low. Many studies have reported that circular RNAs (circRNAs) play a role in promoting the malignant progression of glioma; however, the role of circ_0059914 in this process remains unclear. In this study, we aimed to investigate the function and underlying mechanism of circ_0059914 in glioma. Western blotting and qRT-PCR were used to determine the levels of circ_0059914, miR-1249, VEGFA, N-cadherin, vimentin, Snail, and EIF4A3. EDU and colony formation assays were conducted to evaluate cell proliferation. Transwell assays were used to explore cell migration and invasion and tube formation assays were used to analyze angiogenesis. RNA immunoprecipitation (RIP) and dual-luciferase reporter assays were used to explore the relationship between EIF4A3, circ_0059914, miR-1249, and VEGFA. A xenograft tumor assay was performed to determine the role of circ_0059914 in vivo. Circ_0059914 expression was upregulated in gliomas. Knockdown of gliomal circ_0059914 expression reduced the proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), angiogenesis, and growth of glioma cells in vivo. Circ_0059914 sponged miR-1249, and miR-1249 inhibition reversed the circ_0059914 knockdown-mediated effects in glioma cells. VEGFA was found to be a target gene of miR1249; overexpression of VEGFA reversed the effect of miR-1249 up-regulation in glioma. Finally, EIF4A3 increased the expression of circ_0059914. EIF4A3-induced circ_0059914 expression plays a role in promoting glioma via the miR-1249/VEGFA axis.

Circ_0079471 Regulates the Proliferation, Migration, Invasion and Apoptosis of Osteosarcoma Cells by Mediating miR-485-3p and TRIP6

BACKGROUND

Circular RNAs (circRNAs) are a special class of non-coding RNA molecules that show a closed circular structure and have been implicated in both tumour formation and oncogenesis.

OBJECTIVE

This study aimed to learn more about how circ_0079471 functions in osteosarcomas (OSs).

METHODS

Quantitative real-time polymerase chain reaction was used to detect the expression levels of thyroid hormone receptor-interacting protein 6 (TRIP6), miR-485-3p and circ_0079471. Methyl-thiazolyl-tetrazolium and flow cytometry were used to track cell growth and cell-cycle progression, and the research explored wound healing (migration) and invasion using Transwell plates. Western blotting was used to determine the protein expression of TRIP6, proliferating cell nuclear antigen and cyclin D1, and a dual-luciferase assay revealed the target relationship.

RESULTS

A xenograft experiment evaluated the in vivo effects of circ_0079471 on OS, and the results revealed the high expression of circ_0079471 in OS tissue and cells. The proliferation, cell-cycle migration and invasion of cells were reduced after circ_0079471 knockdown in OS cells; however, the effects of this knockdown were reversed when TRIP6 was overexpressed in the OS cells. The function of circ_0079471 was also achieved by in vivo miR-485-3p sponging. The upregulation of miR-485-3p and the downregulation of TRIP6 partly resulted in circ_0079471 downregulation, which subsequently inhibited OS progression.

CONCLUSION

According to these results, circ_0079471 influences the development of OS by regulating miR-485-3p and TRIP6.

CircSCMH1 Accelerates Sorafenib Resistance in Hepatocellular Carcinoma by Regulating HN1 Expression via miR-485-5p

Sorafenib (SOR) is the first-line chemotherapeutic therapy for hepatocellular carcinoma (HCC) treatment, but SOR resistance is a key factor affecting the therapeutic effect. Emerging studies have suggested that circular RNAs (circRNAs) play an important role in the development of drug resistance in HCC cells. This paper aimed to elucidate the potential role and molecular mechanism of circRNA Scm polycomb group protein homolog 1 (circSCMH1) in SOR-resistant HCC cells. CircSCMH1, microRNA-485-5p (miR-485-5p), and hematological and neurological expressed 1 (HN1) contents were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell Counting Kit-8 (CCK8) assay was adopted to detect the SOR sensitivity of cells. Cell proliferation, migration, invasion, and apoptosis were assessed using colony formation, 5-Ethynyl-2'-deoxyuridine (EdU), transwell, and flow cytometry assays. Glucose metabolism was analyzed using commercial kits. HN1, B cell lymphoma-2 (Bcl-2), and Bcl-2-associated X (Bax) protein levels were assessed using western blot. Binding between miR-485-5p and circSCMH1 or HN1 was verified using a dual-luciferase reporter. Xenograft tumor model was used to explore the function of circSCMH1 in vivo. CircSCMH1 expression and HN1 abundances were increased, but the miR-485-5p level was reduced in SOR-resistant HCC tissues and cells. Deficiency of circSCMH1 enhanced SOR sensitivity by suppressing cell proliferation, migration, invasion, and glucose metabolism and inducing cell apoptosis in SOR-resistant HCC cell lines (Huh7/SOR and Hep3B/SOR). Mechanistically, circSCMH1 sponged miR-485-5p to positively regulate HN1 expression. Importantly, circSCMH1 depletion inhibited tumor growth and increased SOR sensitivity in vivo. CircSCMH1 promoted SOR resistance in HCC cells at least partly through upregulating HN1 expression by sponging miR-485-5p. These findings elucidated a new regulatory pathway of chemo-resistance in SOR-resistant HCC cells and provided a possible circRNA-targeted therapy for HCC.

Circ_0061140 Potentiates Clear Cell Renal Cell Carcinoma Progression Via the MicroRNA-126-5p/ADAM9 Axis

Circular RNAs (circRNAs) function as new cancer biomarkers, but the role of circ_0061140 remains unknown in clear cell renal cell carcinoma (ccRCC). Therefore, we aimed to validate the functions of circ_0061140 in ccRCC and its potential as a prognostic biomarker. At first, circ_0061140 expression in ccRCC tissues and cells was detected, and circ_0061140 was upregulated in ccRCC tissues (p < 0.0001) and cells (p < 0.0001). Patients with high expression of circ_0061140 had a worse prognosis (p < 0.05). Then, siRNA against circ_0061140 was transfected into Caki-1 and UT14 cells to explore its roles in the biological functions of ccRCC cells, and suppressing roles of downregulated circ_0061140 were observed in the cell growth of Caki-1 and UT14 cells (p < 0.01). Next, circ_0061140 was found to be a sponge of miR-126-5p, and ADAM9 was determined to be a target of miR-126-5p. Finally, functional rescue experiments were conducted to observe their roles in ccRCC cell growth. It was suggested that suppressed miR-126-5p or overexpressed ADAM9 induced cell proliferation and restricted cell apoptosis in ccRCC cells based on si-circ_0061140 (p < 0.01). Altogether, this study highlights that circ_0061140 plays an oncogenic role in ccRCC through modulation of the miR-126-5p/ADAM9 axis.

Circular RNA circ_0004630 promotes malignancy and glycolysis of nonsmall cell lung cancer by sponging microRNA-1208 and regulating leucine-rich repeat kinase 2 expression

Emerging evidence has discovered that circular RNAs play important regulators of nonsmall cell lung cancer (NSCLC), but the role and potential molecular mechanism of hsa_circ_100549 (circ_0004630) involved in NSCLC is poorly defined. In this study, circ_0004630, microRNA-1208 (miR-1208), and leucine-rich repeat kinase 2 (LRRK2) expression were detected using real-time quantitative polymerase chain reaction. Cell proliferation, colony formation, apoptosis, and invasion were assessed using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine, colony formation, flow cytometry, and transwell assays. Protein levels of glucose transporter 1, Hexokinase 2, and LRRK2 were detected using western blot assay. Glucose consumption, lactate production, and adenosine triphosphate content were assessed using the corresponding kits. After predicting via bioinformatics software Circinteractome and Targetscan, the binding between miR-1208 and circ_0004630 or LRRK2 was verified by a dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assay. The xenograft tumor model analyzed the biological role circ_000460 on tumor growth in vivo. It was found that circ_0004630 and LRRK2 were increased, and miR-1208 was low expression in NSCLC tissues and cells. Functionally, the downregulation of circ_0004630 inhibited NSCLC cell proliferation, invasion, glycolysis, and accelerated apoptosis in vitro. In mechanism, circ_0004630 might work as a sponge of miR-1208 to modulate LRRK2 expression. In addition, DUXAP8 deficiency cured neuroblastoma tumor growth in vivo. In conclusion, circ_0004630 knockdown might suppress NSCLC cell proliferation, metastasis, and glycolysis partly by the miR-1208/LRRK2 axis. Our findings hinted at an important theoretical basis for further elucidating the pathogenesis of NSCLC and targeted therapy.

The roles of MicroRNAs in cadmium toxicity and in the protection offered by plant food-derived dietary phenolic bioactive substances against cadmium-induced toxicity

Cadmium, a harmful food contaminant, poses severe health risks. There are ongoing efforts to reduce cadmium pollution and alleviate its toxicity, including plant-based dietary intervention. This review hypothesizes that microRNAs (miRNAs), as regulatory eukaryotic transcripts, play crucial roles in modulating cadmium-induced organ damage, and plant food-derived bioactive compounds provide protective effects via miRNA-mediated mechanisms. The review reveals that there are interplays between certain miRNAs and plant food-derived dietary bioactive substances when these bioactives, especially phenolics, counteract cadmium toxicity through regulating physiologic and pathologic events (including oxidative stress, apoptosis, autophagy and inflammation). The review discusses common miRNA-associated physiologic/pathologic events and signal pathways shared by the cadmium toxicity and dietary intervention processes. This paper identifies the existing knowledge gaps and potential future work (e.g. joint actions between miRNAs and other noncoding RNAs in the fights against cadmium). The insights provided by this review can improve food safety strategies and public health outcomes.

YY1/circCTNNB1/miR-186-5p/YY1 positive loop aggravates lung cancer progression through the Wnt pathway

Lung cancer is one familiar cancer that threatens the lives of humans. circCTNNB1 has been disclosed to have regulatory functions in some diseases. However, the functions and related regulatory mechanisms of circCTNNB1 in lung cancer remain largely indistinct. The mRNA and protein expression levels were examined through real-time polymerase chain reaction (RT-qPCR) and western blot. The cell proliferation was tested through CCK-8 assay. The cell migration and invasion were confirmed through Transwell assays. The cell senescence was evaluated through SA-β-gal assay. The binding ability between miR-186-5p and circCTNNB1 (or YY1) was verified through luciferase reporter and RIP assays. In this study, the higher expression of circCTNNB1 was discovered in lung cancer tissues and cell lines and resulted in poor prognosis. In addition, circCTNNB1 facilitated lung cancer cell proliferation, migration, invasion, and suppressed cell senescence. Knockdown of circCTNNB1 retarded the Wnt pathway. Mechanism-related experiments revealed that circCTNNB1 combined with miR-186-5p to target YY1. Through rescue assays, YY1 overexpression could rescue decreased cell proliferation, migration, invasion, increased cell senescence, and retarded Wnt pathway mediated by circCTNNB1 suppression. Furthermore, YY1 acts as a transcription factor that can transcriptionally activate circCTNNB1 to form YY1/circCTNNB1/miR-186-5p/YY1 positive loop. Through in vivo assays, circCTNNB1 accelerated tumour growth in vivo. All findings revealed that a positive loop YY1/circCTNNB1/miR-186-5p/YY1 aggravated lung cancer progression by modulating the Wnt pathway.

Circ_0004872 deficiency attenuates ox-LDL-induced vascular smooth muscle cell dysfunction by miR-424-5p-dependent regulation of FRS2

Atherosclerosis (AS) is a pivotal pathological basis of cardiovascular and cerebrovascular diseases, and circular RNAs (circRNAs) has been disclosed to exert a vital part in the progression of AS. However, the functions of circ_0004872 in the progression of AS is indistinct. In this context, we aimed to elucidate the role of circ_0004872 and the potential mechanism in AS. The level of circ_0004872, miR-424-5p and fibroblast growth factor receptor substrate 2 (FRS2) was detected using quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was monitored by Cell Counting Kit-8 and 5-ethynyl-2'-deoxyuridine (EDU) assays. The invasion and migration capabilities of VSMCs were tested by transwell assays and wound-healing assay, respectively. Western blot was adopted to check the protein levels of CyclinD1, Vimentin and FRS2. Dual-luciferase reporter and RNA immunoprecipitation assay were executed to manifest the interaction between miR-424-5p and circ_0004872 or FRS2. The level of circ_0004872 was increased in the serum samples of AS patients and ox-LDL-exposed VSMCs. Ox-LDL exposure triggered cell proliferation, invasion and migration ability of VSMCs. depletion of circ_0004872 partly weakened ox-LDL-mediated effects in VSMCs. Mechanistically, circ_0004872 functioned as a sponge of miR-424-5p, and miR-424-5p inhibition partly alleviated circ_0004872 deficiency-mediated influences in VSMCs. Additionally, miR-424-5p interacted with FRS2, and miR-424-5p constrained dysfunction in ox-LDL-stimulated VSMCs via reducing FRS2 level. Notably, circ_0004872 functioned as a sponge of miR-424-5p to elevate FRS2 expression. Circ_0004872 accelerated ox-LDL-induced damage via mediating miR-424-5p/FRS2 axis.

Exosome-transported circ_0001955 as a potent driver of breast cancer by regulating the miR-708-5p/PGK1 axis

BACKGROUND

Increasing evidence shows that exosome-mediated delivery of circular RNA (circRNA) is implicated in breast cancer progression. This study aimed to elucidate the role of exosome-transported circ_0001955 in breast cancer.

METHODS

The expression of circ_0001955, miR-708-5p, and phosphoglycerate kinase 1 (PGK1) messenger RNA (mRNA) was detected by quantitative real-time polymerase chain reaction (qRT-PCR); the protein levels of PGK1 and hexokinase 2 (HK2) were detected by western blot (WB). 5'-Ethynyl-2'-deoxyuridine (EdU) and colony formation assay were used to determine cell proliferation. Glycolytic metabolism was analyzed by corresponding kits to detect the associated indicators. The role of circ_0001955 in vivo was studied by establishing animal models. The potential binding relationship between miR-708-5p and circ_0001955 or PGK1 was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

RESULTS

Circ_0001955 was highly expressed in breast cancer tissues and cell lines, as well as in exosomes from breast cancer cell lines. The deficiency of circ_0001955 blocked proliferation, decreased the IC50 value of paclitaxel (PTX), and blocked glycolysis in MCF-7 and MDA-MB-231 cells. Circ_0001955 knockdown also inhibited tumor growth in vivo. Circ_0001955 directly combined with miR-708-5p, and the miR-708-5p inhibitor reversed the effects of sh-circ_0001955. PGK1 was a target of miR-708-5p, and circ_0001955 indirectly promoted PGK1 expression by binding to miR-708-5p. PGK1 overexpression abolished the function of miR-708-5p in breast cancer.

CONCLUSION

Exosomal circ_0001955 excreted from breast cancer cells facilitated proliferation and glycolysis and enhanced the IC50 value of PTX in breast cancer cells by sponging miR-708-5p to upregulate PGK1.

Involvement of selected circulating ncRNAs in the regulation of cognitive dysfunction induced by anesthesia

Post-operative cognitive dysfunction (POCD) refers to the functional impairment of the nervous system caused by prolonged exposure to anesthetics. It is known that prolonged exposure to anesthetics may increase the risk for the development of several cognitive impairments. The drugs used to induce general anesthesia are generally safe, owing to the CNS's direct and/or indirect self-protective activity against drug-induced damages. Non-coding RNAs have recently started to gain attention to better understand the mechanism of gene regulation correlated to cellular physiology and pathology. In order to provide new insights for the neuroprotective function of highly expressed ncRNAs in the central nervous system, we investigated their expression profile in the circulating exosomes of patients exposed to anesthesia vs healthy controls. The experimental design envisaged the recruitment of 30 adult patients undergoing general anesthesia and healthy controls. The effects of anesthetics have been evaluated on miR-34a and miR-124, on the lncRNAs MALAT-1, HOTAIR, GAS5, BLACAT1, HULC, PANDA, and on YRNAs. NcRNAs miR-34a, miR-124, MALAT-1, HOTAIR, GAS5, BLACAT1, and YRNA1 are significantly overexpressed following anesthesia, while YRNA5 is significantly down regulated. Some of them have neuroprotective function, while other correlate with neurological dysfunctions. Our data suggests that, during anesthesia, the toxic action of some non-coding RNAs could be compensated by other non-coding RNAs, both synthesized by the CNS or also transported into neurons from other tissues. It is reasonable to suppose a mutual action of these molecules likely to secure the CNS from anesthetics, that drive a convoluted cascade of ncRNA-dependent biological counter-responses. Our findings are novel in the field of brain dysfunction, indicating that some of the analyzed ncRNAs, although several of their functions still need to be addressed, could be suggested as potential biomarkers and therapeutic targets in post-operative cognitive dysfunction-related processes.

Epigenetic Modulations of Non-Coding RNAs: A Novel Therapeutic Perspective in Sjӧgren's Syndrome

Sjögren's syndrome (SS) is an autoimmune disease that can be classified as an epithelitis based on the immune-mediated attack directed specifically at epithelial cells. SS predominantly affects women, is characterized by the production of highly specific circulating autoantibodies, and the major targets are the salivary and lachrymal glands. Although a genetic predisposition has been amply demonstrated for SS, the etiology remains unclear. The recent integration of epigenetic data relating to autoimmune diseases opens new therapeutic perspectives based on a better understanding of the molecular processes implicated. In the autoimmune field, non-coding RNA molecules (nc-RNA), which regulate gene expression by binding to mRNAs and could have a therapeutic value, have aroused great interest. The focus of this review is to summarize the biological functions of nc-RNAs in the pathogenesis of SS and decode molecular pathways implicated in the disease, in order to identify new therapeutic strategies.

Identification of potential key circular RNAs associated with Escherichia coli-infected bovine mastitis using RNA-sequencing: preliminary study results

Escherichia coli (E. coli) is commonly found in dairy farms and can invade mammary gland tissue, often causing acute clinical mastitis. Mammary infections with E. coli have shown a wide range of clinical signs, causing abnormal appearance of the milk, udder inflammation and systemic signs of illness. Circular RNA is a class of endogenous non-coding RNA that plays an important role in the occurrence and development of various inflammatory diseases. However, there is little information on the circRNA associated with bovine mastitis. In this study investigated the involvement of circRNAs in bovine mastitis through the construction of an E. coli-infected bovine mastitis model by injecting of E. coli into the mammary gland of dairy cows, using healthy gland mammary tissue as a control (M_C). High-throughput RNA-seq was performed on the E. coli-infected mammary gland tissue (M_E) and differentially expressed circRNAs between theM_C and M_E groups, followed by an analysis of their potential functions using bioinformatics methods. A total of 164 differentially expressed circRNAs were identified, including 92 downregulated circRNAs and 72 upregulated circRNAs. As shown by Gene Ontology enrichment analysis these DE circRNAs were mostly enriched in ras protein signal transduction, cytoplasmic vesicle parts, and enzyme binding, and Kyoto Encyclopedia of Genes and genome singal pathway enrichment analysis indicated significant associations with phagosome signal pathway. Additionally, the expression of bovine mastitis-related circRNAs, including novel_circRNA_0000128, novel_circRNA_0011103, novel_circRNA_0012656, novel_circRNA_0015099, novel_circRNA_005648, novel_circRNA_000074, and novel_circRNA_0011796 were verified via quantitative reverse-transcription polymerase chain reaction (RT-qPCR). These results provide a new direction for further investigation of the molecular mechanisms underlying bovine mastitis.

circARID1A Inhibits Tail Fat Cell Differentiation in Guangling Large-Tailed Sheep by Regulating the miR-493-3p/YTHDF2 Axis

The Guangling Large-Tailed sheep is renowned for its unique tail fat deposition, with a significant proportion of its total body fat being localized in the tail region. Fat deposition is a complex biological process regulated by various molecular mechanisms. Our previous studies have identified a large number of differentially expressed circular RNAs (circRNAs) in the tail adipose tissue of the Guangling Large-Tailed sheep. These circRNAs may play a pivotal role in the process of fat deposition. Given the potential regulatory functions of circRNAs in adipose metabolism, investigating their roles in tail fat deposition is of significant scientific importance. In this study, we identified novel circARID1A. Using various experimental methods, including lentivirus infection, RNase R treatment, actinomycin D assay, qPCR, western blotting, and dual-luciferase reporter assays, we determined that circARID1A inhibits the expression of miR-493-3p through competitive binding, thereby regulating adipocyte differentiation. Further research revealed that miR-493-3p promotes adipocyte differentiation by targeting YTH domain family 2 (YTHDF2), and this regulatory effect is also influenced by circARID1A. In conclusion, our findings suggest that circARID1A inhibits tail fat cell differentiation in the Guangling Large-Tailed sheep through the circARID1A/miR-493-3p/YTHDF2 axis, providing theoretical support for improving meat quality and fat deposition in sheep.

CircZNF609/miR-324-5p/voltage-dependent anion channel 1 axis promotes malignant progression of ovarian cancer cells

The dysregulation of circular RNAs (circRNAs) has been associated with OC development and progression. This study investigated the role of circZNF609 in ovarian cancer (OC) by analyzing its impact on cell proliferation, migration, and invasion. Initially, the study assessed the expression of circZNF609 in OC tissues and adjacent normal tissues. The results revealed elevated circZNF609 levels in OC tissues and cell lines, correlating with poor prognosis, lymph node metastasis, and advanced clinical stage. Subsequently, in vitro and in vivo experiments were conducted to elucidate the biological functions of circZNF609 in OC progression. The findings showed that the knockdown of circZNF609 resulted in reduced OC cell proliferation, migration, invasion, and tumor growth. Mechanistically, circZNF609 was identified to function as a sponge for miR-324-5p, thereby upregulating voltage-dependent anion channel 1 (VDAC1) expression and promoting OC progression. Our findings indicate that circZNF609 promotes OC via the miR-324-5p/VDAC1 axis, contributing to the therapeutic targeting of this disease.

CircRNA profiling of skeletal muscle satellite cells in goats reveals circTGFβ2 promotes myoblast differentiation

BACKGROUND

Circular RNAs (circRNAs) function as essential regulatory elements with pivotal roles in various biological processes. However, their expression profiles and functional regulation during the differentiation of goat myoblasts have not been thoroughly explored. This study conducts an analysis of circRNA expression profiles during the proliferation phase (cultured in growth medium, GM) and differentiation phase (cultured in differentiation medium, DM1/DM5) of skeletal muscle satellite cells (MuSCs) in goats.

RESULTS

A total of 2,094 circRNAs were identified, among which 84 were differentially expressed as determined by pairwise comparisons across three distinct groups. Validation of the expression levels of six randomly selected circRNAs was performed using reverse transcription PCR (RT-PCR) and quantitative RT-PCR (qRT-PCR), with confirmation of their back-splicing junction sites. Enrichment analysis of the host genes associated with differentially expressed circRNAs (DEcircRNAs) indicated significant involvement in biological processes such as muscle contraction, muscle hypertrophy, and muscle tissue development. Additionally, these host genes were implicated in key signaling pathways, including Hippo, TGF-beta, and MAPK pathways. Subsequently, employing Cytoscape, we developed a circRNA-miRNA interaction network to elucidate the complex regulatory mechanisms underlying goat muscle development, encompassing 21 circRNAs and 47 miRNAs. Functional assays demonstrated that circTGFβ2 enhances myogenic differentiation in goats, potentially through a miRNA sponge mechanism.

CONCLUSION

In conclusion, we identified the genome-wide expression profiles of circRNAs in goat MuSCs during both proliferation and differentiation phases, and established that circTGFβ2 plays a role in the regulation of myogenesis. This study offers a significant resource for the advanced exploration of the biological functions and mechanisms of circRNAs in the myogenesis of goats.