With the development of high-throughput sequencing technology, circular RNAs (circRNAs) have gradually become a hotspot in the research on non-coding RNA. CircRNAs are produced by the covalent circularization of a downstream 3' splice donor and an upstream 5' splice acceptor through backsplicing, and they are pervasive in eukaryotic cells. CircRNAs used to be considered byproducts of false splicing, whereas an explosion of related studies in recent years has disproved this misconception. Compared with the rich studies of circRNAs in animals, the study of circRNAs in plants is still in its infancy. In this review, we introduced the discovery of plant circRNAs, the discovery of plant circRNAs, the circularization feature, expression specificity, conservation, and stability of plant circRNAs and expounded the identification tools, main types, and biogenesis mechanisms of circRNAs. Furthermore, we summarized the potential roles of plant circRNAs as microRNA (miRNA) sponges and translation templates and in response to biotic/abiotic stress, and briefed the degradation and localization of plant circRNAs. Finally, we discussed the challenges and proposed the future directions in the research on plant circRNAs.
Animals ; MicroRNAs/metabolism* ; Organelle Biogenesis ; Plants/metabolism* ; Protein Biosynthesis/physiology* ; RNA, Circular/metabolism* ; RNA, Plant/metabolism* ; Research/trends* ; Stress, Physiological/genetics*

Circular RNAs (circRNAs) are currently classed as non-coding RNAs that, unlike the better known canonical linear RNAs, form a covalently closed continuous loop without 5′ or 3′ polarities. With the development of high throughput sequencing technology, a large number of circRNAs have been discovered in many species. More importantly, growing evidence suggests that circRNAs are abundant, evolutionally conserved, and relatively stable in cells and tissues. Strikingly, recent studies have discovered that circRNAs can serve as microRNA sponges, interact with RNA-binding protein, and regulate gene transcription, as well as protein translation. Osteoarthritis (OA) is the most common chronic degenerative joint disease. CircRNAs are differentially expressed in OA cartilage. Moreover, some circRNAs are involved in multiple pathological processes during OA, mainly extracellular matrix degradation, inflammation, and apoptosis. In this review, we briefly delineate the biogenesis, characteristics, and biofunctions of circRNAs, and then, focus on the role of circRNAs in the occurrence and progression OA.
Apoptosis ; Cartilage ; Cartilage, Articular ; Extracellular Matrix ; Inflammation ; Joint Diseases ; MicroRNAs ; Osteoarthritis* ; Pathologic Processes ; Porifera ; Protein Biosynthesis ; RNA* ; RNA, Untranslated ; RNA-Binding Proteins

This study was performed to investigate a potential marker for the presence of spermatozoa in the ejaculate following varicocelectomy in Chinese men with nonobstructive azoospermia and varicoceles. The micro-RNA (miR)-192a levels in seminal plasma and testicular tissue were evaluated by quantitative real-time polymerase chain reaction from 60 men with nonobstructive azoospermia and varicoceles (Group A: 27 men with spermatozoa found in the ejaculate after surgery; Group B: 33 men without spermatozoa found in the ejaculate after surgery) and 30 controls. The seminal plasma and testicular tissue miR-192a levels were higher in Group B than in Group A and the controls (P < 0.001), and there was no significant difference between Group A and the controls (P > 0.05). Apoptosis and proliferation assays with miR mimics and inhibitors showed that miR-192a induced GC-2 cell apoptosis through the activation of Caspase-3 protein. Thus, seminal plasma miR-192a appears to be a potential marker for successfully indicating spermatozoa in the ejaculate following microsurgical varicocelectomy in men with nonobstructive azoospermia and varicoceles. Seminal plasma miR-192a may be a useful clinical marker for prescreening to determine which patients with nonobstructive azoospermia and varicoceles would benefit from varicocelectomy.
Adult ; Apoptosis ; Asian People ; Azoospermia/surgery* ; Biomarkers/analysis* ; Caspase 3/analysis* ; Cell Proliferation ; Humans ; Infertility, Male/etiology* ; Male ; MicroRNAs/biosynthesis* ; Microsurgery ; Predictive Value of Tests ; Semen/metabolism* ; Testis/metabolism* ; Treatment Outcome ; Varicocele/surgery*

Objective To investigate effect of let-7a gene over-expression on apoptosis of gastric cancer cell lines SGC-7901.Methods The stable let-7a gene over-expressing SGC-7901 cells, SGC-7901/let-7a cells, were established using shRNA lentiviral vector methods. Real-time RT-PCR analysis was used to evaluate the expression level of let-7a mRNA. Cells apoptosis was assessed by flow cytometry.Results RT-PCR analysis revealed let-7a expression in SGC-7901/let-7a cells was significantly increased. Cellular apoptosis assay showed that over-expression of let-7a could increase apoptosis of SGC-7901 cells (P=0.002).Conclusion Up-regulating let-7a expression promoted apoptosis in SGC-7901 cells.
Apoptosis ; Cell Line, Tumor ; Gene Expression Regulation, Neoplastic ; Humans ; MicroRNAs ; biosynthesis ; genetics ; RNA, Neoplasm ; biosynthesis ; genetics ; Stomach Neoplasms ; genetics ; metabolism ; pathology ; Up-Regulation

Stroke is one of the leading causes of death and physical disability worldwide. The consequences of stroke injuries are profound and persistent, causing in considerable burden to both the individual patient and society. Current treatments for ischemic stroke injuries have proved inadequate, partly owing to an incomplete understanding of the cellular and molecular changes that occur following ischemic stroke. MicroRNAs (miRNA) are endogenously expressed RNA molecules that function to inhibit mRNA translation and have key roles in the pathophysiological processes contributing to ischemic stroke injuries. Potential therapeutic areas to compensate these pathogenic processes include promoting angiogenesis, neurogenesis and neuroprotection. Several miRNAs, and their target genes, are recognized to be involved in these recoveries and repair mechanisms. The capacity of miRNAs to simultaneously regulate several target genes underlies their unique importance in ischemic stroke therapeutics. In this Review, we focus on the role of miRNAs as potential diagnostic and prognostic biomarkers, as well as promising therapeutic agents in cerebral ischemic stroke.
Biomarkers ; Cause of Death ; Humans ; Ischemia ; MicroRNAs* ; Neurogenesis ; Neuroprotection ; Protein Biosynthesis ; RNA ; Stroke*

MicroRNAs (miRNAs) recruit the RNA-induced silencing complex (RISC) to repress the translation of target mRNAs. While the 5' 7-methylguanosine cap of target mRNAs has been well known to be important for miRNA repression, the underlying mechanism is not clear. Here we show that TNRC6A interacts with eIF4E2, a homologue of eIF4E that can bind to the cap but cannot interact with eIF4G to initiate translation, to inhibit the translation of target mRNAs. Downregulation of eIF4E2 relieved miRNA repression of reporter expression. Moreover, eIF4E2 downregulation increased the protein levels of endogenous IMP1, PTEN and PDCD4, whose expression are repressed by endogenous miRNAs. We further provide evidence showing that miRNA enhances eIF4E2 association with the target mRNA. We propose that miRNAs recruit eIF4E2 to compete with eIF4E to repress mRNA translation.
Autoantigens ; metabolism ; Cell Line ; Eukaryotic Initiation Factor-4E ; metabolism ; Gene Silencing ; Humans ; MicroRNAs ; genetics ; Protein Transport ; RNA, Messenger ; biosynthesis ; genetics ; RNA-Binding Proteins ; metabolism

MTUS1 (microtubule-associated tumor suppressor 1) has been identified that can function as a tumor suppressor gene in many malignant tumors. However, the function and mechanisms underlying the regulation of MTUS1 are unclear. In the present study, we reported that miR-19a and miR-19b (miR-19a/b) promote proliferation and migration of lung cancer cells by targeting MTUS1. First, MTUS1 was proved to function as a tumor suppressor in lung cancer and was linked to cell proliferation and migration promotion. Second, an inverse correlation between miR-19a/b expression and MTUS1 mRNA/protein expression was noted in human lung cancer tissues. Third, MTUS1 was appraised as a direct target of miR-19a/b by bioinformatics analysis. Fourth, direct MTUS1 regulation by miR-19a/b in lung cancer cells was experimentally affirmed by cell transfection assay and luciferase reporter assay. Finally, miR-19a/b were shown to cooperatively repress MTUS1 expression and synergistically regulate MTUS1 expression to promote lung cancer cell proliferation and migration. In conclusion, our findings have provided the first clues regarding the roles of miR-19a/b, which appear to function as oncomirs in lung cancer by downregulating MTUS1.
A549 Cells ; Cell Movement ; Cell Proliferation ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Lung Neoplasms ; genetics ; metabolism ; pathology ; Male ; MicroRNAs ; genetics ; metabolism ; RNA, Neoplasm ; genetics ; metabolism ; Tumor Suppressor Proteins ; biosynthesis ; genetics

Animals ; Gene Expression Regulation ; physiology ; Gills ; metabolism ; Intestinal Mucosa ; metabolism ; Lancelets ; genetics ; metabolism ; Liver ; metabolism ; MicroRNAs ; biosynthesis ; genetics

Many studies informed that microRNAs (miRNAs) could function as diagnostic and prognostic indicators in several cancers. The aims of this study were to explore the expression of miR-630 in bladder urothelial carcinoma and its clinical significance for the evaluation of cancer prognosis. A total of 116 patients with bladder urothelial carcinoma were obtained in this retrospective study between May, 2012 and Sep. 2015. Quantitative real-time PCR (qRT-PCR) was conducted to evaluate the expression level of miR-630. The chi-square test was used to examine the associations between miR-630 expression and the clinicopathological features. The Kaplan-Meier method was conducted to explore the survival status of urothelial carcinoma patients. The log-rank test was used to analyze differences in survival rate. The results showed an obvious increase in miR-630 expression from normal bladder to bladder urothelial carcinoma (P=0.027). Additionally, patients with higher miR-630 expression had significantly shorter disease-free survival (DFS) (P=0.043) and overall survival (OS) (P=0.038) than those with lower miR-630 expression. Furthermore, multivariate analysis revealed that up-regulation of miR-630 was an independent prognostic factor for both DFS (P=0.042) and OS (P=0.046). It was demonstrated that miR-630 may be a novel and valuable prognostic factor for bladder urothelial carcinoma.
Adult ; Aged ; Biomarkers, Tumor ; biosynthesis ; genetics ; Carcinoma ; genetics ; pathology ; Disease-Free Survival ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Kaplan-Meier Estimate ; Male ; MicroRNAs ; biosynthesis ; genetics ; Middle Aged ; Neoplasm Staging ; Prognosis ; Urinary Bladder Neoplasms ; genetics ; pathology ; Urothelium ; pathology

The let-7 miRNA was one of the first miRNAs discovered in the nematode, Caenorhabditis elegans, and its biological functions show a high level of evolutionary conservation from the nematode to the human. Unlike in C. elegans, higher animals have multiple isoforms of let-7 miRNAs; these isoforms share a consensus sequence called the 'seed sequence' and these isoforms are categorized into let-7 miRNA family. The expression of let-7 family is required for developmental timing and tumor suppressor function, but must be suppressed for the self-renewal of stem cells. Therefore, let-7 miRNA biogenesis must be carefully controlled. To generate a let-7 miRNA, a primary transcript is produced by RNA polymerase II and then subsequently processed by Drosha/DGCR8, TUTase, and Dicer. Because dysregulation of let-7 processing is deleterious, biogenesis of let-7 is tightly regulated by cellular factors, such as the RNA binding proteins, LIN28A/B and DIS3L2. In this review, we discuss the biological functions and biogenesis of let-7 miRNAs, focusing on the molecular mechanisms of regulation of let-7 biogenesis in vertebrates, such as the mouse and the human.
Animals ; Base Sequence ; Gene Expression Regulation ; Humans ; MicroRNAs ; biosynthesis ; chemistry ; genetics ; metabolism ; RNA Processing, Post-Transcriptional ; RNA Stability ; Transcription, Genetic