circNFXL1 Modulates the Kv2.1 Channel Function in Hypoxic Human Pulmonary Artery Smooth Muscle Cells via Sponging miR-29b-2-5p as a Competitive Endogenous RNA

ABSTRACT

Pulmonary arterial hypertension is characterized by abnormal pulmonary vasoconstriction and vascular remodeling caused by the dysregulation of K + channels in PA smooth muscle cells (PASMCs). However, how the K + channels are dysregulated is still unclear. Circular RNAs (circRNAs) are noncoding RNAs with a closed-loop structure capable of sponging microRNAs (miRs), thus regulating gene expression at the post-transcriptional level. Our previous studies have demonstrated the importance of one novel circRNA (hsa_circNFXL1_009, circNFXL1) in pulmonary arterial hypertension patients, playing as a critical regulator for K + channel activation in hypoxic human PASMCs (hPASMCs). Here, we explore the mechanisms underlying circNFXL1-regulated K + channel expression and functions in hypoxic hPASMCs. In cultured hPASMCs, the reduction of Kv current induced by hypoxia was significantly recovered by delivering exogenous circNFXL1. Moreover, luciferase, quantitative reverse transcription-quantitative polymerase chain reaction, western blot, and mutagenesis studies confirmed that circNFXL1 reversed hypoxia-induced inhibitory effects on the Kv2.1 channel via sponging hsa-miR-29b-2-5p (miR-29b-2). Furthermore, we found that circNFXL1 reversed the miR-29b-induced Kv2.1 channel dysfunction at the whole-cell and single-channel level in HEK cells using a patch-clamp. Finally, calcium imaging revealed that hypoxia also triggered a substantial rise in the cytosolic calcium concentration ([Ca2 + ]cyt) in hPASMCs, and this hypoxia-induced elevation of [Ca2 + ]cyt was reduced by circNFXL1 through miR-29b-2. These data suggested that circNFXL1-mediated regulation of the Kv2.1 channel activation and the related intracellular calcium concentration may contribute to the effects of hypoxic pulmonary vasoconstriction.

mRNA therapeutics: new vaccination and beyond

The idea of mRNA therapy had been conceived for decades before it came into reality during the Covid-19 pandemic. The mRNA vaccine emerges as a powerful and general tool against new viral infections, largely due to its versatility and rapid development. In addition to prophylactic vaccines, mRNA technology also offers great promise for new applications as a versatile drug modality. However, realizing the conceptual potential faces considerable challenges, such as minimal immune stimulation, high and long-term expression, and efficient delivery to target cells and tissues. Here we review the applications of mRNA-based therapeutics, with emphasis on the innovative design and future challenges/solutions. In addition, we also discuss the next generation of mRNA therapy, including circular mRNA and self-amplifying RNAs. We aim to provide a conceptual overview and outlook on mRNA therapeutics beyond prophylactic vaccines.

Circ0005654 as a new biomarker of thyroid cancer interacting with SP1 to influence the prognosis: A case-control study

Circular RNAs (CircRNAs) have been reported to play key roles in the progression of various cancers, including thyroid cancer (TC). Transcription factor 1 (SP1) promotes the development of thyroid cancer. This study aims at investigating the expression level of Circ0005654 in combination with Transcription factor1 (SP1) in patients with TC for diagnostic and therapeutic purposes. A total of 76 patients with thyroid cancer underwent radical surgery. Intraoperatively, thyroid cancer tissues and paired adjacent tissues and the corresponding clinicopathological data were collected. The expression of SP1 and β-catenin in thyroid cancer and adjacent tissues was determined by immunohistochemistry (IHC) while the Circ0005654 expression level was measured by semiquantitative real-time polymerase chain reaction (sqRT-PCR). Then, we compared the variability of Circ0005654, SP1, and Wnt/β-catenin expression in cancerous and adjacent tissues and determined the relationship between the correlation analysis and the clinicopathological features of the thyroid cancer patients. The diagnostic value of Circ0005654 in thyroid cancer tissues was analyzed with the help of the receiver operating characteristic (ROC) curve, counting the 3-year postoperative survival rate, and analyzing the effect of Circ0005654 and SP1 protein levels on the 3-year survival rate of the patients. sqRT-PCR showed that the expression level of Circ0005654 in thyroid cancer tissue was significantly higher than that of adjacent tissues. The area under the ROC of Circ0005654 was 0.9553, 95% confidence interval: (0.9211-0.9895) with a cutoff value of 0.7895, a sensitivity of 92.11%, and a specificity of 86.84%. The IHC results showed that the expression level of SP1, β-catenin, and Wnt was higher in cancer tissues than in adjacent tissues; Circ0005654, SP1, Wnt/β-catenin expression levels were associated with tumor diameter, lymph node metastasis, TNM stage, and envelope invasion (all P < .05). According to the Circ0005654 expression level in thyroid cancer tissue, the 3-year survival rate of the high expression group was 77.5% and 94.4% in the low expression group with a statistically significant difference; the 3-year survival rate of SP1 positive and negative patients was 78.6% and 100%, respectively, with the data being significantly different. Circ0005654 may serve as a potential biomarker for thyroid cancer diagnosis and may be involved in the development of thyroid cancer.

Beyond transcription factors: more regulatory layers affecting soybean gene expression under abiotic stress

Abiotic stresses such as nutritional imbalance, salt, light intensity, and high and low temperatures negatively affect plant growth and development. Through the course of evolution, plants developed multiple mechanisms to cope with environmental variations, such as physiological, morphological, and molecular adaptations. Epigenetic regulation, transcription factor activity, and post-transcriptional regulation operated by RNA molecules are mechanisms associated with gene expression regulation under stress. Epigenetic regulation, including histone and DNA covalent modifications, triggers chromatin remodeling and changes the accessibility of transcription machinery leading to alterations in gene activity and plant homeostasis responses. Soybean is a legume widely produced and whose productivity is deeply affected by abiotic stresses. Many studies explored how soybean faces stress to identify key elements and improve productivity through breeding and genetic engineering. This review summarizes recent progress in soybean gene expression regulation through epigenetic modifications and circRNAs pathways, and points out the knowledge gaps that are important to study by the scientific community. It focuses on epigenetic factors participating in soybean abiotic stress responses, and chromatin modifications in response to stressful environments and draws attention to the regulatory potential of circular RNA in post-transcriptional processing.

Bioinformatics analysis of the circRNA-miRNA-mRNA network for atrial fibrillation

Atrial fibrillation (AF) is a chronic and progressive disease, with advancing age, the morbidity of which will increase exponentially. Circular ribonucleic acids (RNAs; circRNAs) have gained a growing attention in the development of AF in recent years. The purpose of this study is to explore the mechanism of circRNA regulation in AF, in particular, the intricate interactions among circRNA, microRNA (miRNA), and messenger RNA (mRNA). Three datasets (GSE129409, GSE68475, and GSE79768) were obtained from the Gene Expression Omnibus database to screen differentially expressed (DE) circRNAs, DE miRNAs, and DE mRNAs in AF, respectively. Based on circRNA-miRNA pairs and miRNA-mRNA pairs, a competing endogenous RNAs (ceRNAs) network was built. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis of DE mRNAs in the network were performed and protein-protein interaction (PPI) networks were established to identify hub genes. Finally, a circRNA-miRNA-hub gene subnetwork was constructed. A total of 103 DE circRNAs, 16 DE miRNAs, and 110 DE mRNAs were screened in AF. Next, ceRNAs network in AF was constructed with 3 upregulated circRNAs, 2 downregulated circRNAs, 2 upregulated miRNAs, 2 downregulated miRNAs, 17 upregulated mRNAs, and 24 downregulated mRNAs. Thirty GO terms and 6 KEGG pathways were obtained. Besides, 6 hub genes (C-X-C chemokine receptor type 4 [CXCR4], C-X-C chemokine receptor type 2 [CXCR2], C-X-C motif chemokine 11 [CXCL11], neuromedin-U, B1 bradykinin receptor, and complement C3) were screened from constructing a PPI network. Finally, a circRNA-miRNA-hub gene subnetwork with 10 regulatory axes was constructed to describe the interactions among the differential circRNAs, miRNA, and hub genes. We speculated that hsa_circRNA_0056281/hsa_circRNA_0006665 -hsa-miR-613-CXCR4/CXCR2/CXCL11 regulatory axes and hsa_circRNA_0003638-hsa-miR-1207-3p-CXCR4 regulatory axis may be associated with the pathogenesis of AF.

Circular RNA Plasmacytoma Variant Translocation 1 (CircPVT1) knockdown ameliorates hypoxia-induced bladder fibrosis by regulating the miR-203/Suppressor of Cytokine Signaling 3 (SOCS3) signaling axis

The effects of circular RNAs (circRNAs) on bladder outlet obstruction (BOO)-induced hypertrophy and fibrogenesis in rats and hypoxia-induced bladder smooth muscle cell (BSMC) fibrosis remain unclear. This study aimed to determine the regulatory role of circRNAs in the phenotypic changes in BSMCs in BOO-induced rats.circRNAmicroarray and real-time PCR were used to explore differentiated expressed circRNAs. Bioinformatics analyses and dual-luciferase reporter were performed to identify the targets for circRNA PVT1 (circPVT1). BOO was performed to establish a bladder fibrosis animal model. The circPVT1 and suppressor of cytokine signaling 3 (SOCS3) expression levels were upregulated (p = 0.0061 and 0.0328, respectively), whereas the microRNA-203a (miR-203) level was downregulated in rats with bladder remodeling (p=0.0085). Bioinformatics analyses and dual-luciferase reporter assay results confirmed that circPVT1 sponges miR-203 and that the latter targets the 3'-untranslated region of SOCS3. Additionally, circPVT1 knockdown alleviated BOO-induced bladder hypertrophy and fibrogenesis. Furthermore, hypoxia was induced in BSMCs to establish a cell model of bladder fibrosis. Hypoxia induction in BSMCs resulted in upregulated circPVT1 and SOCS3 levels (p = 0.0052) and downregulated miR-203 levels. Transfection with circPVT1 and SOCS3 shRNA ameliorated hypoxia-induced transforming growth factor-β (TGF-β1), TGFβR1, α-smooth muscle actin, fibrotic growth factor, extracellular matrix subtypes, BSMC proliferation, and apoptosis-associated cell injury, whereas co-transfection with miR-203 inhibitor counteracted the effect of circPVT1 shRNA on these phenotypes.These findings revealed a novel circRNA regulator of BOO-associated bladder wall remodeling and hypoxia-induced phenotypic changes in BMSCs by targeting the miR-203-SOCS3 signaling axis.

Novel circular RNA circATRNL1 accelerates the osteosarcoma aerobic glycolysis through targeting miR-409-3p/LDHA

In recent researches, circular RNAs (circRNAs) have been shown to exert critical functions in osteosarcoma biology. Nevertheless, the contribution of circRNAs to osteosarcoma remains largely unclear. Results indicated that expression of circATRNL1 was higher in osteosarcoma tissues and cells. The high-expression of circATRNL1 was significantly correlated with aggressive features and acted as an independent risk factor for osteosarcoma patients' overall survival. Functionally, our findings demonstrate that circATRNL1 promotes the osteosarcoma aerobic glycolysis in vitro. Mechanistically, circATRNL1 up-regulated the expression level of LDHA, which was also targeted by miR-409-3p. Therefore, circATRNL1 exerted the accelerative roles of osteosarcoma aerobic glycolysis through miR-409-3p/LDHA axis. In conclusion, circATRNL1 promoted osteosarcoma progression by enhancing glycolysis via circATRNL1/miR-409-3p/LDHA axis, which may inspire a novel therapeutic target for osteosarcoma.

Alu RNA and their roles in human disease states

Alu RNA are implicated in the poor prognosis of several human disease states. These RNA are transcription products of primate specific transposable elements called Alu elements. These elements are extremely abundant, comprising over 10% of the human genome, and 100 to 1000 cytoplasmic copies of Alu RNA per cell. Alu RNA do not have a single universal functional role aside from selfish self-propagation. Despite this, Alu RNA have been found to operate in a diverse set of translational and transcriptional mechanisms. This review will focus on the current knowledge of Alu RNA involved in human disease states and known mechanisms of action. Examples of Alu RNA that are transcribed in a variety of contexts such as introns, mature mRNA, and non-coding transcripts will be discussed. Past and present challenges in studying Alu RNA, and the future directions of Alu RNA in basic and clinical research will also be examined.

环状RNA在炎症所致早产小鼠脑损伤中的作用及机制初步研究

OBJECTIVE

To determine the association of circular RNA (circRNA) and circRNA-microRNA (miRNA) network regulation with brain injury induced by inflammation in preterm mice.

METHODS

Pregnant mice were treated with intraperitoneally injected lipopolysaccharide to establish a preterm mouse model of brain injury induced by inflammation (inflammation preterm group with 3 mice). Preterm mice born to normal pregnant mice by cesarean section were selected as controls (non-inflammation preterm group with 3 mice). The gene microarray technique was used to screen out the circRNAs associated with brain injury in preterm mice. The miRNA target prediction software was used to predict the binding sites between circRNAs and miRNAs and analyze the regulatory mechanism.

RESULTS

A total of 365 differentially expressed circRNAs were screened out between the inflammation preterm and non-inflammation preterm groups (fold change > 1.5, P < 0.05), among which there were 206 upregulated circRNAs and 159 downregulated circRNAs. Further analysis of the circRNAs with a fold change of > 4 showed that these circRNAs could bind to miRNAs and regulate their activity, thereby regulating the expression of the genes associated with the nervous system.

CONCLUSIONS

Inflammation induces a significant change in the expression profile of circRNAs in the brain tissue of mice, and the change in the expression of circRNAs plays an important role in brain injury induced by inflammation and subsequent brain development in preterm mice.

Clinicopathological and prognostic significance of circRNAs in lung cancer: A systematic review and meta-analysis

BACKGROUND

Circular RNAs (circRNAs) regulate multiple pathways during lung cancer pathogenesis. Apart from functional significance, many circRNAs have been shown to be associated with clinicopathological characteristics and predict lung cancer prognosis. Our aim is to summarize the expanding knowledge of clinical roles of circRNAs in lung cancer.

METHODS

A thorough search of literature was conducted to identify articles about the correlation between circRNA expression and its prognostic and clinicopathological values. Biological mechanisms were summarized.

RESULTS

This study included 35 original articles and 32 circRNAs with prognostic roles for lung cancer. Increased expression of 25 circRNAs and decreased expression of 7 circRNAs predicted poor prognosis. For non-small cell lung cancer, changes of circRNAs were correlated with tumor size, lymph node metastasis, distant metastasis, tumor node metastasis (TNM) stage, and differentiation, indicating the major function of circRNAs is to promote lung cancer invasion and migration. Particularly, meta-analysis of ciRS-7, hsa_circ_0020123, hsa_circ_0067934 showed increase of the 3 circRNAs was associated with positive lymph node metastasis. Increase of ciRS-7 and hsa_circ_0067934 was also related with advanced TNM stage. The biological effects depend on the general function of circRNA as microRNA sponge.

CONCLUSIONS

CircRNAs have the potential to function as prognostic markers and are associated with lung cancer progression and metastasis.

Circular RNA circPIKfyve acts as a sponge of miR-21-3p to enhance antiviral immunity through regulating MAVS in teleost fish

Circular RNAs (circRNAs) are a class of widespread and diverse covalently closed circular endogenous RNAs that exert crucial functions in regulating gene expression in mammals. However, the function and regulation mechanism of circRNAs in lower vertebrates are still unknown. Here, we discovered a novel circRNA derived from PIKfyve, named circPIKfyve, that is related to the antiviral responses in teleost fish. The results showed that circPIKfyve plays essential roles in host antiviral immunity and inhibition of SCRV replication. Moreover, we also found that the antiviral effect inhibited by miR-21-3p could be reversed with the addition of circPIKfyve. In mechanism, our data revealed that circPIKfyve is a competitive endogenous RNA (ceRNA) of MAVS by sponging miR-21-3p, leading to activation of NF-κB/IRF3 pathway, which then enhance the innate antiviral responses. In addition, we firstly found that RNA binding protein QKI is involved in the formation and regulation of circPIKfyve. Our results provided a strong basis that circRNAs to play a regulatory role in antiviral immune responses in teleost fish.Importance: Here, we identified a novel circRNA, namely, circPIKfyve, that can act as a key regulator of the innate immune response in teleost fish. circPIKfyve acts as a molecular sponge by competitive adsorbing of miR-21-3p, thereby increasing the abundance of MAVS and activating the downstream NF-κB/IRF3 pathway to enhance the antiviral response. In addition, this study was the first to find that QKI protein is involved in regulating the formation of circPIKfyve in fish. The overall results of this study suggest that circPIKfyve plays an active regulatory role in the antiviral immune response of teleost fish.

A Circle RNA Regulatory Axis Promotes Lung Squamous Metastasis via CDR1-Mediated Regulation of Golgi Trafficking

Lung squamous carcinoma (LUSC) is a highly metastatic disease with a poor prognosis. Using an integrated screening approach, we found that miR-671-5p reduces LUSC metastasis by inhibiting a circular RNA (circRNA), CDR1as. Although the putative function of circRNA is through miRNA sponging, we found that miR-671-5p more potently silenced an axis of CDR1as and its antisense transcript, cerebellar degeneration related protein 1 (CDR1). Silencing of CDR1as or CDR1 significantly inhibited LUSC metastases and CDR1 was sufficient to promote migration and metastases. CDR1, which directly interacted with adaptor protein 1 (AP1) complex subunits and coatomer protein I (COPI) proteins, no longer promoted migration upon blockade of Golgi trafficking. Therapeutic inhibition of the CDR1as/CDR1 axis with miR-671-5p mimics reduced metastasis in vivo. This report demonstrates a novel role for CDR1 in promoting metastasis and Golgi trafficking. These findings reveal an miRNA/circRNA axis that regulates LUSC metastases through a previously unstudied protein, CDR1. SIGNIFICANCE: This study shows that circRNA, CDR1as, promotes lung squamous migration, metastasis, and Golgi trafficking through its complimentary transcript, CDR1.

[Continuous expression and functional prediction of circular RNA in mouse lung development]

OBJECTIVE

To study the continuous expression and potential function of circular RNA (circRNA), circ4:150439343|150477468 and circ15:73330849|73343359, in mouse lung development.

METHODS

According to the stage of lung development, lung tissue samples were collected from mice on embryonic day 16.5 (E16.5), embryonic day 18.5 (E18.5), and postnatal day 2 (P2). Hematoxylin and eosin staining was performed to observe the morphology of lung tissue. Quantitative real-time PCR (qRT-PCR) was used to measure the mRNA expression of circ4:150439343|150477468 and circ15:73330849|73343359 during late lung development; miRanda and TargetScan were used to predict the target miRNAs of circRNAs, and then GO and KEGG analysis was performed for the target genes to predict the potential function of circRNAs.

RESULTS

Type II alveolar epithelial cells were observed in the lung slices of E16.5 mice, with a gradual increase in number. On P2, the pulmonary alveoli expanded rapidly, the pulmonary interstitium became thinner, and the alveolar structure gradually became mature. The results of qRT-PCR showed that the relative expression of circ4:150439343|150477468 was continuously upregulated over time and the relative expression of circ15:73330849|73343359 was first downregulated and then upregulated (P<0.05). The KEGG and GO analysis showed that circRNAs were involved in the Notch, PI3K-Akt, and NF-κB signaling pathways.

CONCLUSIONS

Circ4:150439343|150477468 and circ15:73330849|73343359 can participate in lung development through the Notch signaling pathway.

Emerging role of circular RNA in intervertebral disc degeneration: Knowns and unknowns (Review)

Lower back pain (LBP) is one of the predominant factors contributing to dyskinesia and remains a serious social and economic burden worldwide. Intervertebral disc degeneration (IDD) is the leading cause of LBP; the existing IDD treatments cannot completely prevent IDD. Circular RNAs (circRNAs) are non‑coding RNAs resulting from back‑splicing with unique structural characteristics and functions. Accumulating evidence suggests that circRNAs are involved in the pathological process of IDD and modulate a range of IDD‑related genes or proteins. However, the underlying circRNA‑mediated regulatory mechanisms remain poorly understood. The aim of the present review is to describe the current understanding of circRNA characteristics, classification, biogenesis and function in relation to its specific roles in IDD. Additionally, the limitations on the current knowledge in the field and the future direction of IDD‑related research are also discussed.

Expression profile of circular RNAs in the peripheral blood of neonates with hypoxic‑ischemic encephalopathy

Circular RNAs (circRNAs) are a class of non-coding RNAs that participate in various biological processes. However, the function of circRNAs in neonatal hypoxic‑ischemic encephalopathy (HIE) is not fully understood. In the present study, the differentially expressed circRNAs in the peripheral blood of neonates with HIE and control samples were characterized by a microarray assay. A total of 456 circRNAs were significantly differentially expressed in the peripheral blood of neonates with HIE, with 250 upregulated and 206 downregulated circRNAs in HIE compared with the control samples. Reverse transcription‑quantitative PCR was used to investigate specific circRNAs. Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes pathway analyses were used to determine the function of the parent genes of the dysregulated circRNAs. In addition, microRNAs that may be associated with specific circRNAs were predicted using miRanda. Collectively, the present results indicated the potential importance of circRNAs in the peripheral blood of neonates with HIE.

Circular RNA hsa_circ_0001380 in peripheral blood as a potential diagnostic biomarker for active pulmonary tuberculosis

Numerous studies have suggested that circular RNAs (circRNAs), a type of non-coding RNA lacking 5′-caps and 3′-poly(A) tails, are involved in the biological processes of various human diseases. However, little is known about their functions and diagnostic value in active pulmonary tuberculosis (APTB). The aim of the present study was to examine whether hsa_circ_0001380 is able to serve as a diagnostic biomarker for patients with APTB. The expression level of hsa_circ_0001380 was detected in the peripheral blood of 32 patients with APTB and 31 healthy volunteers by reverse transcription-quantitative PCR. The functional prediction of hsa_circ_0001380 was performed in silico. RNase R was used to detect the stability of hsa_circ_0001380. Finally, the diagnostic value of hsa_circ_0001380 was evaluated by receiver operating characteristic (ROC) curve analysis. The results showed that hsa_circ_0001380 was significantly downregulated in the peripheral blood of patients with APTB. In addition, hsa_circ_0001380 was found to be resistant to RNase R treatment. Moreover, four N6-adenosine methylation modification sites and two potential microRNA binding sites were predicted in silico. Importantly, the area under the ROC curve was 0.9502, which suggested that hsa_circ_0001380 may act as a diagnostic biomarker for APTB. Taken together, the results indicated that circRNA hsa_circ_0001380 was downregulated in the peripheral blood of patients with APTB, and could serve as a diagnostic biomarker.

lncRNA/circRNA‑miRNA‑mRNA ceRNA network in lumbar intervertebral disc degeneration

Accumulating evidence has indicated that noncoding RNAs are involved in intervertebral disc degeneration (IDD); however, the competing endogenous RNA (ceRNA)‑mediated regulatory mechanisms in IDD remain rarely reported. The present study aimed to comprehensively investigate the alterations in expression levels of circular RNA (circRNA), long noncoding RNA (lncRNA), microRNA (miRNA/miR) and mRNA in the nucleus pulposus (NP) of patients with IDD. In addition, crucial lncRNA/circRNA‑miRNA‑mRNA ceRNA interaction axes were screened using the GSE67567 microarray dataset obtained from the Gene Expression Omnibus database. After data preprocessing, differentially expressed circRNAs (DECs), lncRNAs (DELs), miRNAs (DEMs) or genes (DEGs) between IDD and normal controls were identified using the Linear Models for Microarray data method. A protein‑protein interaction (PPI) network was constructed for DEGs based on protein databases, followed by module analysis. The ceRNA network was constructed based on the interaction between miRNAs and mRNAs, and lncRNAs/circRNAs and miRNAs. The underlying functions of mRNAs were predicted using the Database for Annotation, Visualization and Integrated Discovery database. The present study identified 636 DECs, 115 DELs, 84 DEMs and 1,040 DEGs between patients with IDD and control individuals. PPI network analysis demonstrated that Fos proto‑oncogene, AP‑1 transcription factor subunit (FOS), mitogen‑activated protein kinase 1 (MAPK1), hypoxia inducible factor 1 subunit α (HIF1A) and transforming growth factor β1 (TGFB1) were hub genes and enriched in modules. Metastasis‑associated lung adenocarcinoma transcript 1 (MALAT1)/hsa_circRNA_102348‑hsa‑​miR‑185‑5p‑TGFB1/FOS, MALAT1‑hsa‑miR‑155‑5p‑HIF1A, hsa_circRNA_102399‑hsa‑miR‑302a‑3p‑HIF1A, MALAT1‑hsa‑​miR‑519d‑3p‑MAPK1 and hsa_circRNA_100086‑hsa‑miR‑509‑3p‑MAPK1 ceRNA axes were obtained by constructing the ceRNA networks. In conclusion, these identified ceRNA interaction axes may be crucial targets for the treatment of IDD.

Differential circular RNA expression profiles of invasive and non-invasive non-functioning pituitary adenomas: A microarray analysis

Non-functioning pituitary adenomas (NFPAs) are the most common pituitary tumors, and some exhibit locally invasive or even clinically aggressive behavior. Circular RNAs (circRNAs) are a reinvented class of non-coding RNAs that play important roles in tumor initiation and progression.CircRNA microarray assays were performed in 4 invasive and 4 non-invasive NFPAs, and 4 typically differential expression circRNAs were selected for validation using quantitative reverse transcription-polymerase chain reaction. The diagnostic and prognostic values of tested cirRNAs were further evaluated. Bioinformatics analysis and a literature review of potential miRNAs targets involved in pituitary tumor invasion were performed.A specific circRNA expression profile was detected between invasive and non-invasive NFPAs, including 91 upregulated and 61 downregulated circRNAs in invasive tumors. The dysregulation of the 4 circRNAs has been confirmed. The expression of hsa_circRNA_102597, a downregulated circRNA, was significantly correlated with tumor diameter (P < .05) and Knosp grade (P < .01). Hsa_circRNA_102597 alone or in combined with Ki-67 index was able to accurately differentiate invasive from non-invasive NFPAs as well as predict tumor progression/recurrence. Fourteen aberrantly expressed circRNAs might be involved in the invasiveness of pituitary adenomas via seven predicted potential miRNA targets.CircRNAs are participated in pituitary tumor invasion, and may be used as novel diagnostic and prognostic biomarkers in NFPAs.

Expression of circular RNAs in gynecological tumors: A systematic review

BACKGROUND

The rapid development of bioinformatic technology is boosting the discovery of components hiding in the darkness. As a type of universal, conservative, tissue-specific and stable molecules, circular RNA (circRNA) is a class of endogenous non-coding RNA that has no 5' cap and 3' poly(A) tail and forms a covalently closed continuous loop. At present, 3 types of circRNAs including exonic circRNA (ecRNA), intronic circRNA (ciRNA), and axon-intronic circRNA have been reported. Nowadays informatic technology and high-throughput sequencing have verified the abundance of endogenous circRNAs in eukaryocytes, with predominantly expressed in the cell cytoplasm. Their unique sequences endow them with special functions, such as miRNA sponge, selective transcription or splicing, and attaching to RNA-binding proteins.

DATA SOURCES

This review was based on articles published in PubMed databases up to January, 2019, with the following keywords: "circular RNA", "database", and "reproductive tumor" (Flow chart).

OBJECTIVES

Original articles and reviews on the topics were selected.

RESULTS

Studies have uncovered the interplay between circRNAs and the development of ovarian epithelial tumors, ovarian carcinoma, and cervical carcinoma, which suggesting the potential of circRNAs as biomarkers or therapeutic targets for human diseases.

CONCLUSIONS

Circular RNA has been found to play a role in gynecological tumors diseases. Meanwhile, we reviewed the studies on how CircularRNA participate in gynecological tumors, which provides a basis for the study of CircularRNA in gynecological tumors.

Expression profile of circular RNAs in infantile hemangioma detected by RNA-Seq

BACKGROUND

Circular RNAs (circRNAs) have emerged as a novel class of widespread non-coding RNAs, and they play crucial roles in various biological processes. However, the characterization and function of circRNAs in infantile hemangioma (IH) remain elusive.

METHODS

In this study, we used RNA-Seq and circRNA prediction to study and characterize the circRNAs in IH tissue and a matched normal skin control. Specific circRNAs were verified using real-time polymerase chain reaction.

RESULTS AND CONCLUSION

We found that of the 9811 identified circRNAs, 249 candidates were differentially expressed, including 124 upregulated and 125 downregulated circRNAs in the IH group compared with the matched normal skin control group. A set of differentially expressed circRNAs (in particular, hsa_circRNA001885 and hsa_circRNA006612 expression) were confirmed using qRT-PCR. Gene ontology and pathway analysis revealed that compared to matched normal skin tissues, many processes that were over-represented in IH group were related to the binding, protein binding, gap junction, and focal adhesion. Specific circRNAs were associated with several micro-RNAs (miRNAs) predicted using miRanda. Altogether, our findings highlight the potential importance of circRNAs in the biology of IH and its response to treatment.

The RNA strands of the plus and minus polarities of peach latent mosaic viroid fold into different structures

It is believed that peach latent mosaic viroid (PLMVd) strands of both the plus and minus polarities fold into similar secondary and tertiary structures. In order to verify this hypothesis, the behavior of both strands in three biophysical assays was examined. PLMVd transcripts of plus and minus polarity were found to exhibit distinct electrophoretic mobility properties under native conditions, to precipitate differently in the presence of lithium chloride, and to possess variable thermal denaturation profiles. Subsequently, the structure of PLMVd transcripts of minus polarity was elucidated by biochemical methods, thereby permitting comparison to the known structure of the plus polarity. Specifically, enzymatic probing, electrophoretic mobility shift assay, and ribonuclease H hydrolysis were performed in order to resolve the secondary structure of the minus polarity. The left domains of the strands of both polarities appear to be similar, while the right domain exhibited several differences even though they both adopted a branched structure. The pseudoknot P8 formed in the plus strand seemed not formed in the minus strands. The structural differences between the two polarities might have important implications in various steps of the PLMVd life cycle.

Two reactions of Haloferax volcanii RNA splicing enzymes: joining of exons and circularization of introns

Archaeal RNA splicing involves at least two protein enzymes, a specific endonuclease and a specific ligase. The endonuclease recognizes and cleaves within a characteristic bulge-helix-bulge (BHB) structure formed by pairing of the regions near the two exon-intron junctions, producing 2',3'-cyclic phosphate and 5'-hydroxyl termini. The ligase joins the exons and converts the cyclic phosphate into junction phosphate. The ligated product contains a seven-base hairpin loop, in which the splice junction is in between the two 3' terminal residues of the loop. Archaeal splicing endonucleases are also involved in rRNA processing, cutting within the BHB structures formed by pairing of the 5' and 3' flanking regions of the rRNAs. Large free introns derived from pre-rRNAs have been observed as stable and abundant circular RNAs in certain Crenarchaeota, a kingdom in the domain Archaea. In the present study, we show that the cells of Haloferax volcanii, a Euryarchaeote, contain circular RNAs formed by 3',5'-phosphodiester linkage between the two termini of the introns derived from their pre-tRNAs. H. volcanii ligase, in vitro, can also circularize both endonuclease-cleaved introns, and non-endonuclease-produced substrates. Exon joining and intron circularization are mechanistically similar ligation reactions that can occur independently. The size of the ligated hairpin loop and position of the splice junction within this loop can be changed in in vitro ligation reactions. Overall, archaeal RNA splicing seems to involve two sets of two symmetric transesterification reactions each.