AGO2 and its partners: a silencing complex, a chromatin modulator, and new features

LINC00460/miR-186-3p/MYC feedback loop facilitates colorectal cancer immune escape by enhancing CD47 and PD-L1 expressions

BACKGROUND

Long non-coding RNAs (LncRNAs) have been implicated as critical regulators of cancer tumorigenesis and progression. However, their functions and molecular mechanisms in colorectal cancer (CRC) still remain to be further elucidated.

METHODS

LINC00460 was identified by differential analysis between human CRC and normal tissues and verified by in situ hybridization (ISH) and qRT-PCR. We investigated the biological functions of LINC00460 in CRC by in vitro and in vivo experiments. We predicted the mechanism and downstream functional molecules of LINC00460 by bioinformatics analysis, and confirmed them by dual luciferase reporter gene assay, RNA immunoprecipitation (RIP), RNA pull-down, etc. RESULTS: LINC00460 was found to be significantly overexpressed in CRC and associated with poor prognosis. Overexpression of LINC00460 promoted CRC cell immune escape and remodeled a suppressive tumor immune microenvironment, thereby promoting CRC proliferation and metastasis. Mechanistic studies showed that LINC00460 served as a molecular sponge for miR-186-3p, and then promoted the expressions of MYC, CD47 and PD-L1 to facilitate CRC cell immune escape. We also demonstrated that MYC upregulated LINC00460 expression at the transcriptional level and formed a positive feedback loop.

CONCLUSIONS

The LINC00460/miR-186-3p/MYC feedback loop promotes CRC cell immune escape and subsequently facilitates CRC proliferation and metastasis. Our findings provide novel insight into LINC00460 as a CRC immune regulator, and provide a potential therapeutic target for CRC patients.

Hsa_circ_0054220 Upregulates HMGA1 by the Competitive RNA Pattern to Promote Neural Impairment in MPTP Model of Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disease. Circular RNAs (circRNAs) have been confirmed to regulate neurodegenerative diseases. This study was aimed to explore hsa_circ_0054220 functions in PD. MPP-stimulated SH-SY5Y cells were established as the PD cell model. PD mouse model was established by MPTP. Gene expression in cells and tissues was tested by RT-qPCR. Cell viability and apoptosis were evaluated through CCK-8 and TUNEL assays. The interactions of RNAs were determined by RNA pull-down assay, RIP assay, and luciferase reporter assay. Circ_0054220 expressed at a high level in MPP-treated SH-SY5Y cells. Circ_0054220 inhibition promoted viability and suppressed apoptosis in MPP-stimulated cells. Furthermore, we found that circ_0054220 can competitively bind to miR-145 and miR-625 to upregulate high mobility group A1 (HMGA1) expression. HMGA1 was positively regulated by circ_0054220 and overexpressed in MPP-treated cells as well as the striatum (STR), substantia nigra pars compacta (SNpc), and serum of MPTP-induced mouse model of PD. HMGA1 overexpression counteracted the function of circ_0054220 silencing on cell apoptosis. Furthermore, HMGA1 inhibition notably alleviated motor dysfunction and increased the quantity of neurons in mice resembling PD. Circ_0054220 upregulates HMGA1 by the competitive endogenous RNAs (ceRNA) pattern to promote neural impairment in PD.

Nomograms incorporating hsa_circ_0029325 highly expressed in exosomes of hepatocellular carcinoma predict the postoperative outcomes

BACKGROUND

Liquid biopsies, for example, exosomal circular RNA (circRNA) can be used to assess potential predictive markers for hepatocellular carcinoma (HCC) in patients after curative resection. This study aimed to search for effective prognostic biomarkers for HCC in patients after surgical resection based on exosomal circRNA expression profiles. We developed two nomograms incorporating circRNAs to predict the postoperative recurrence-free survival (RFS) and overall survival (OS) of HCC patients.

METHOD

Plasma exosomes isolated from HCC patients and healthy individuals were used for circRNA microarray analysis to explore differentially expressed circRNAs. Pearson correlation analysis was used to evaluate the correlation between circRNAs and clinicopathological features. Cox regression analysis was used to explore the correlation between circRNA and postoperative survival time as well as recurrence time. A nomogram based on circRNA and clinicopathological characteristics was established and further evaluated to predict prognosis and recurrence.

RESULT

Among 60 significantly upregulated circRNAs and 25 downregulated circRNAs, hsa_circ_0029325 was selected to verify its power for predicting HCC outcomes. The high expression level of exosomal hsa_circ_0029325 was significantly correlated with OS (P = 0.001, HR = 2.04, 95% CI 1.41-3.32) and RFS (P = 0.009, HR = 1.62, 95% CI 1.14-2.30). Among 273 HCC patients, multivariate regression analysis showed that hsa_circ_0029325 (HR = 1.96, 95% CI 1.21-3.18), tumor size (HR = 2.11, 95% CI 1.33-3.32), clinical staging (HR = 2.31, 95% CI 1.54-3.48), and tumor thrombus (HR = 1.74, 95% CI 1.12-2.7) were independent risk factors for poor prognosis in HCC patients after radical resection. These independent predictors of prognosis were incorporated into the two nomograms. The AUCs under the 1-year, 3-year, and 5-year survival and recurrence curves of the OS and RFS nomograms were 0.755, 0.749, and 0.742 and 0.702, 0.685, and 0.642, respectively. The C-index, calibration curves, and clinical decision curves showed that the two prediction models had good predictive performance. These results were verified in the validation cohort with 90 HCC patients.

CONCLUSION

Our study established two reliable nomograms for predicting recurrence and prognosis in HCC patients. We also show that it is feasible to screen potential predictive markers for HCC after curative resection through exosomal circRNA expression profile analysis.

MicroRNA-320a enhances LRWD1 expression through the AGO2/FXR1-dependent pathway to affect cell behaviors and the oxidative stress response in human testicular embryonic carcinoma cells

BACKGROUND

Testicular cancer is fairly rare but can affect fertility in adult males. Leucine-rich repeats- and WD repeat domain-containing protein 1 (LRWD1) is a sperm-specific marker that mainly affects sperm motility in reproduction. Our previous study demonstrated the impact of LRWD1 on testicular cancer development; however, the underlying mechanisms remain unclear.

METHODS

In this study, various plasmids associated with LRWD1 and miR-320a manipulation were used to explore the roles and regulatory effects of these molecules in NT2D1 cellular processes. A Dual-Glo luciferin-luciferase system was used to investigate LRWD1 transcriptional activity, and qRT-PCR and western blotting were used to determine gene and protein expression.

RESULTS

The results suggested that miR-320a positively regulated LRWD1 and positively correlated with NT2D1 cell proliferation but negatively correlated with cell migration and invasion ability. In addition, the miRNA-ribonucleoprotein complex AGO2/FXR1 was shown to be essential in the mechanism by which miR-320a regulates LRWD1 mRNA expression. As miR-320a was required to regulate LRWD1 expression through the AGO2 and FXR1 complex, eEF2 and eLF4E were also found to be involved in miR-320a increasing LRWD1 expression. Furthermore, miR-320a and LRWD1 were responsive to oxidative stress, and NRF2 was affected by the presence of miR-320a in response to ROS stimulation.

CONCLUSIONS

This is the first study showing the role of miR-320a in upregulating the testicular cancer-specific regulator LRWD1 and the importance of the AGO2/FXR1 complex in miR-320a-mediated upregulation of LRWD1 during testicular cancer progression.

LncRNA SNHG5 adversely governs follicular growth in PCOS via miR-92a-3p/CDKN1C axis

Small nucleolar RNA host genes (SNHGs) have been implicated in various biological processes, yet their involvement in polycystic ovary syndrome (PCOS) remains elusive. Specifically, SNHG5, a long non-coding RNA implicated in several human cancers, shows elevated expression in granulosa cells (GCs) of PCOS women and induces PCOS-like features when overexpressed in mice. In vitro, SNHG5 inhibits GC proliferation and induces apoptosis and cell-cycle arrest at G0/G1 phase, with RNA-seq indicating its impact on DNA replication and repair pathways. Mechanistically, SNHG5 acts as a competing endogenous RNA by binding to miR-92a-3p, leading to increased expression of target gene CDKN1C, which further suppresses GC proliferation and promotes apoptosis. These findings elucidate the crucial role of SNHG5 in the pathogenesis of PCOS and suggest a potential therapeutic target for this condition. Additional investigations such as large-scale clinical studies and functional assays are warranted to validate and expand upon these findings.

Circular RNA CircSATB2 facilitates osteosarcoma progression through regulating the miR-661/FUS-mediated mRNA of ZNFX1

Circular RNAs (circRNAs) are a class of non-coding RNAs which take part in the regulation of the initiation and development of different types of cancer. Numerous studies have demonstrated that circRNAs are involved in the progression of osteosarcoma (OS) as well. Thus, we put our emphasis on the exploration of crucial circRNAs in the process of OS initiation and progression. Using RNA sequencing, we found that circSATB2 was highly expressed in OS tissues compared with adjacent normal tissues. Then, we confirmed the high expression of circSATB2 in OS cell lines and OS tissues and its high expression was related to poor prognosis of OS patients. Functional experiments exhibited that circSATB2 promoted OS proliferation and migration in vitro, primary OS model and OS lung metastasis model showed that circSATB2 aggravated OS progression in vivo. Mechanistically, circSATB2 was found to promote OS progression through sponging miR-661 and FUS regulating the mRNA of ZNFX1. Therefore, circSATB2 could act as a prognostic marker and a therapeutic target for osteosarcoma in the future.

Cutting through the stress: RNA decay pathways at the endoplasmic reticulum

The endoplasmic reticulum (ER) is central to the processing of luminal, transmembrane, and secretory proteins, and maintaining a functional ER is essential for organismal physiology and health. Increased protein-folding load on the ER causes ER stress, which activates quality control mechanisms to restore ER function and protein homeostasis. Beyond protein quality control, mRNA decay pathways have emerged as potent ER fidelity regulators, but their mechanistic roles in ER quality control and their interrelationships remain incompletely understood. Herein, we review ER-associated RNA decay pathways - including regulated inositol-requiring enzyme 1α (IRE1α)-dependent mRNA decay (RIDD), nonsense-mediated mRNA decay (NMD), and Argonaute-dependent RNA silencing - in ER homeostasis, and highlight the intricate coordination of ER-targeted RNA and protein decay mechanisms and their association with antiviral defense.

CircCDK1 blocking IGF2BP2-mediated m6A modification of CPPED1 promotes laryngeal squamous cell carcinoma metastasis via the PI3K/AKT signal pathway

BACKGROUND

Circular RNA (circRNA) is a novel noncoding RNA (ncRNA) that plays a critical role in various cancers. However, the clinical significance, biological function, and molecular mechanisms of circRNAs in laryngeal squamous cell carcinoma (LSCC) remain unclear.

METHODS

A circRNA array was performed to identify the differentially expressed circRNAs. In vitro and in vivo assays were proceeded to verify the biological function of circCDK1 in LSCC. RNA pulldown assays and RNA immunoprecipitation (RIP) were used to confirm the binding between circCDK1 and insulin-like growth factor 2 mRNA binding protein 2(IGF2BP2). The MeRIP assay was then used to identified the N6-methyladenisine (m6A) methylation of calcineurin like phosphatase domain containing1 (CPPED1).

RESULTS

Hsa_circ_0005774 (circCDK1) was found upregulated in LSCC tissues compared to adjacent normal tissues. The level of circCDK1 was positively correlated with poor prognosisof LSCC patients. In vitro and in vivo, circCDK1 promoted migration and invasion of LSCC cells. Mechanistically, eukaryotic translation initiation factor4A3(EIF4A3) induced biogenesis of circCDK1 by binding to its flanking. By competitively binding to IGF2BP2, circCDK1 blocked the m6A modification of CPPED1 in IGF2BP2-dependent manner. Moreover, the circCDK1-mediated decrease of CPPED1 activated the PI3K/AKT signal pathway to facilitate progression of LSCC.

CONCLUSIONS

Our findings demonstrated that EIF4A3-induced upregulation of circCDK1 promoted LSCC metastasis via EIF4A3-circCDK1-IGF2BP2-CPPED1 to activate PI3K-AKT signal pathway. CircCDK1 might serve as a new diagnostic and prognostic marker or potential therapeutic target for LSCC.

Identification and characterization of differentially expressed circular RNAs in extraocular muscle of oculomotor nerve palsy

BACKGROUND

Oculomotor nerve palsy (ONP) is a neuroparalytic disorder resulting in dysfunction of innervating extraocular muscles (EOMs), of which the pathological characteristics remain underexplored.

METHODS

In this study, medial rectus muscle tissue samples from four ONP patients and four constant exotropia (CXT) patients were collected for RNA sequencing. Differentially expressed circular RNAs (circRNAs) were identified and included in functional enrichment analysis, followed by interaction analysis with microRNAs and mRNAs as well as RNA binding proteins. Furthermore, RT-qPCR was used to validate the expression level of the differentially expressed circRNAs.

RESULTS

A total of 84 differentially expressed circRNAs were identified from 10,504 predicted circRNAs. Functional enrichment analysis indicated that the differentially expressed circRNAs significantly correlated with skeletal muscle contraction. In addition, interaction analyses showed that up-regulated circRNA_03628 was significantly interacted with RNA binding protein AGO2 and EIF4A3 as well as microRNA hsa-miR-188-5p and hsa-miR-4529-5p. The up-regulation of circRNA_03628 was validated by RT-qPCR, followed by further elaboration of the expression, location and clinical significance of circRNA_03628 in EOMs of ONP.

CONCLUSIONS

Our study may shed light on the role of differentially expressed circRNAs, especially circRNA_03628, in the pathological changes of EOMs in ONP.

Exosomal lncRNA Mir100hg derived from cancer stem cells enhance glycolysis and promote metastasis of lung adenocarcinoma through mircroRNA-15a-5p/31-5p

BACKGROUND

Exosomes are a new class of molecular entities in the metastatic microenvironment, which can mediate bidirectional communication between cells. While exosomes-mediated interactions between tumor cells and other cell populations in the tumor microenvironment have attracted most attention, little is known about the significance of exosomes in mediating the interaction between non-stemness cancer cells and cancer stem cells during cancer progression.

METHODS

The structure, sequence and downstream target miRNAs of lncRNA Mir100hg were predicted by online web resources. The bioinformatics prediction results were validated with experimental verification: exosome tracing, electron microscopy, Luciferase assay, metabolomics sequencing and mouse tail vein model of pulmonary metastasis. A complex regulatory network of "cancer stem cells-exosomal lncRNA-non-stem cancer cells" was constructed.

RESULTS

This study demonstrates firstly that lncRNA Mir100hg is upregulated in lung cancer stem cell LLC-SD (Lung cancer stem cells) and can be delivered to non-stemness cancer cells LLC (Lewis lung cancer cells) via exosomes. In LLC, Mir100hg targets miR-15a-5p and miR-31-5p which leads to the increase of the global glycolytic activity of lung cancer cells and consequently, the enhancement of their metastatic capability.

CONCLUSION

We delineated a complex regulatory network that utilized by cancer stem cells to transfer their high metastatic activity to the low-metastatic non-stemness cancer cells through exosomal Mir100hg, thereby providing new mechanistic insights into the communication between two heterogeneous tumor cells. Video Abstract.

The dysregulation of lncRNAs by epigenetic factors in human pathologies

Dysregulation of long noncoding RNAs (lncRNAs) contributes to numerous human diseases, including cancers and autoimmune diseases (ADs). Given the importance of lncRNAs in disease initiation and progression, a deeper understanding of their complex regulatory network is required to facilitate their use as therapeutic targets for ADs. In this review, we summarize how lncRNAs are dysregulated in pathological states by epigenetic factors, including RNA-binding proteins, chemical modifications (N6-methyladenosine, 5-methylcytosine, 7-methylguanosine, adenosine-to-inosine editing, microRNA, alternative splicing, DNA methylation, and histone modification). Moreover, the roles of lncRNA epigenetic regulators in immune response and ADs are discussed, providing new insights into the complicated epigenetic factor-lncRNA network, thus, laying a theoretical foundation for future research and clinical application of lncRNAs.

Analysis of m7G-Related signatures in the tumour immune microenvironment and identification of clinical prognostic regulators in breast cancer

BACKGROUND

Breast cancer is a malignant tumour that seriously threatens women's life and health and exhibits high inter-individual heterogeneity, emphasising the need for more in-depth research on its pathogenesis. While internal 7-methylguanosine (m7G) modifications affect RNA processing and function and are believed to be involved in human diseases, little is currently known about the role of m7G modification in breast cancer.

METHODS AND RESULTS

We elucidated the expression, copy number variation incidence and prognostic value of 24 m7G-related genes (m7GRGs) in breast cancer. Subsequently, based on the expression of these 24 m7GRGs, consensus clustering was used to divide tumour samples from the TCGA-BRCA dataset into four subtypes based on significant differences in their immune cell infiltration and stromal scores. Differentially expressed genes between subtypes were mainly enriched in immune-related pathways such as 'Ribosome', 'TNF signalling pathway' and 'Salmonella infection'. Support vector machines and multivariate Cox regression analysis were applied based on these 24 m7GRGs, and four m7GRGs-AGO2, EIF4E3, DPCS and EIF4E-were identified for constructing the prediction model. An ROC curve indicated that a nomogram model based on the risk model and clinical factors had strong ability to predict the prognosis of breast cancer. The prognoses of patients in the high- and low-TMB groups were significantly different (p = 0.03). Moreover, the four-gene signature was able to predict the response to chemotherapy.

CONCLUSIONS

In conclusion, we identified four different subtypes of breast cancer with significant differences in the immune microenvironment and pathways. We elucidated prognostic biomarkers associated with breast cancer and constructed a prognostic model involving four m7GRGs. In addition, we predicted the candidate drugs related to breast cancer based on the prognosis model.

CTLA4 mRNA is downregulated by miR-155 in regulatory T cells, and reduced blood CTLA4 levels are associated with poor prognosis in metastatic melanoma patients

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is an immune checkpoint expressed in regulatory T (Treg) cells and activated T lymphocytes. Despite its potential as a treatment strategy for melanoma, CTLA-4 inhibition has limited efficacy. Using data from The Cancer Genome Atlas (TCGA) melanoma database and another dataset, we found that decreased CTLA4 mRNA was associated with a poorer prognosis in metastatic melanoma. To investigate further, we measured blood CTLA4 mRNA in 273 whole-blood samples from an Australian cohort and found that it was lower in metastatic melanoma than in healthy controls and associated with worse patient survival. We confirmed these findings using Cox proportional hazards model analysis and another cohort from the US. Fractionated blood analysis revealed that Treg cells were responsible for the downregulated CTLA4 in metastatic melanoma patients, which was confirmed by further analysis of published data showing downregulated CTLA-4 surface protein expression in Treg cells of metastatic melanoma compared to healthy donors. Mechanistically, we found that secretomes from human metastatic melanoma cells downregulate CTLA4 mRNA at the post-transcriptional level through miR-155 while upregulating FOXP3 expression in human Treg cells. Functionally, we demonstrated that CTLA4 expression inhibits the proliferation and suppressive function of human Treg cells. Finally, miR-155 was found to be upregulated in Treg cells from metastatic melanoma patients compared to healthy donors. Our study provides new insights into the underlying mechanisms of reduced CTLA4 expression observed in melanoma patients, demonstrating that post-transcriptional silencing of CTLA4 by miRNA-155 in Treg cells may play a critical role. Since CTLA-4 expression is downregulated in non-responder melanoma patients to anti-PD-1 immunotherapy, targeting miRNA-155 or other factors involved in regulating CTLA4 expression in Treg cells without affecting T cells could be a potential strategy to improve the efficacy of immunotherapy in melanoma. Further research is needed to understand the molecular mechanisms regulating CTLA4 expression in Treg cells and identify potential therapeutic targets for enhancing immune-based therapies.

Circular RNA hsa_circ_0007444 inhibits ovarian cancer progression through miR-23a-3p/DICER1 axis

Ovarian cancer is the second leading cause of death in women with gynecological malignancy in China. Circular RNAs are a class of noncoding regulatory RNAs reported to be involved in cancer development and progression. Previous studies, including our own, have indicated that hsa_circ_0007444 is downregulated in ovarian cancer tissues. This study aims to elucidate the function and mechanism of hsa_circ_0007444 in ovarian cancer progression. The expression of hsa_circ_0007444 is determined by quantitative real-time PCR (qRT-PCR). Cell proliferation, invasion, migration and apoptosis are examined by cell counting-kit 8 (CCK-8), transwell and flow cytometry assays. Tumor growth and metastasis are assessed in vivo using Balb/c nude mouse xenograft model and tail vein injection model. And the mechanism of action of hsa_circ_0007444 is analysed by RNA-binding protein immunoprecipitation (RIP), luciferase reporter and rescue assays. hsa_circ_0007444 is downregulated in ovarian cancer tissues and cell lines compared with that in normal ovarian tissues and normal epithelial cell line. Gain- and loss-of-function results indicate that hsa_circ_0007444 inhibits cell proliferation, invasion, migration and increases cell apoptosis of ovarian cancer cells in vitro, and inhibits tumor growth and lung metastasis in vivo. Mechanistically, hsa_circ_0007444 can interact with AGO2 and sponge miR-23a-3p, thereby upregulating DICER1 expression, which is an important tumor suppressor in ovarian cancer. And miR-23a-3p mimics can rescue the inhibitory effect of hsa_circ_0007444 on ovarian cancer cell proliferation, invasion and migration. Therefore, hsa_circ_0007444 can inhibit ovarian cancer progression through the hsa_circ_0007444/miR-23a-3p/DICER1 axis.

SNORD60 promotes the tumorigenesis and progression of endometrial cancer through binding PIK3CA and regulating PI3K/AKT/mTOR signaling pathway

Endometrial carcinoma is a common gynecological malignant tumor, small nucleolar RNAs (snoRNAs) are involved in cancer development. However, researches on the roles of snoRNAs in endometrial carcinoma are limited. The expression levels of snoRNAs in endometrial cancer tissues were analyzed using The Cancer Genome Atlas (TCGA) database. Antisense oligonucleotides (ASOs) and plasmids were used for transfection. Moreover, CCK-8, EdU, wound-healing assay, transwell, cell apoptosis, western blotting, and xenograft model were employed to examine the biological functions of related molecules. real-time reverse transcription polymerase chain reaction and western blotting were performed to detect messenger RNA (mRNA) and protein levels. Including bioinformatics, fluorescence in situ hybridization, RNA pulldown, actinomycin D and RTL-P assays were also carried out to explore the molecular mechanism. Analysis of data from TCGA showed that the expression level of small nucleolar RNA, C/D box 60 (SNORD60) in endometrial cancer tissues is observably higher than that in normal endometrial tissues. Further research suggested that SNORD60 played a carcinogenic role both in vitro and in vivo, and significantly upregulated the expression of PIK3CA. However, the carcinogenic effects can be reversed by knocking down fibrillarin (FBL) or PIK3CA. SNORD60 forms complexes by binding with 2'-O-methyltransferase fibrillarin, thus catalyzes the 2'-O-methylation (Nm) modification of PIK3CA mRNA and modulates the PI3K/AKT/mTOR signaling pathway, so as to promote the development of endometrial cancer. In short, SNORD60 might become a new biomarker for the therapy of endometrial cancer in the future and provide new strategies for diagnosis and treatment.

miRNA biogenesis and inherited disorders: clinico-molecular insights

MicroRNAs (miRNAs) play vital roles in the regulation of gene expression, a process known as miRNA-induced gene silencing. The human genome codes for many miRNAs, and their biogenesis relies on a handful of genes, including DROSHA, DGCR8, DICER1, and AGO1/2. Germline pathogenic variants (GPVs) in these genes cause at least three distinct genetic syndromes, with clinical manifestations that range from hyperplastic/neoplastic entities to neurodevelopmental disorders (NDDs). Over the past decade, DICER1 GPVs have been shown to lead to tumor predisposition. Moreover, recent findings have provided insight into the clinical consequences arising from GPVs in DGCR8, AGO1, and AGO2. Here we provide a timely update with respect to how GPVs in miRNA biogenesis genes alter miRNA biology and ultimately lead to their clinical manifestations.

Construction of Fusion Protein for Enhanced Small RNA Loading to Extracellular Vesicles

Extracellular vesicles (EVs) naturally carry cargo from producer cells, such as RNA and protein, and can transfer these messengers to other cells and tissue. This ability provides an interesting opportunity for using EVs as delivery vehicles for therapeutic agents, such as for gene therapy. However, endogenous loading of cargo, such as microRNAs (miRNAs), is not very efficient as the copy number of miRNAs per EV is quite low. Therefore, new methods and tools to enhance the loading of small RNAs is required. In the current study, we developed fusion protein of EV membrane protein CD9 and RNA-binding protein AGO2 (hCD9.hAGO2). We show that the EVs engineered with hCD9.hAGO2 contain significantly higher levels of miRNA or shRNA (miR-466c or shRNA-451, respectively) compared to EVs that are isolated from cells that only overexpress the desired miRNA or shRNA. These hCD9.hAGO2 engineered EVs also transfer their RNA cargo to recipient cells more efficiently. We were not able to detect changes in gene expression levels in recipient cells after the EV treatments, but we show that the cell viability of HUVECs was increased after hCD9.hAGO2 EV treatments. This technical study characterizes the hCD9.hAGO2 fusion protein for the future development of enhanced RNA loading to EVs.

The relationship between miRNA-210 and SCN1B in fetal rats with hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury contributes to major neurodevelopmental disorders and is one of the leading causes of seizures, which substantially results in neurodevelopmental impairments with long-lasting outcomes and is one of the main causes of death in neonates. We aimed to investigate the correlation between miRNA-210 and SCN1B, a voltage-gated sodium channel gene, in brain tissue of fetal rats with hypoxic-ischemic brain injury. We found that after 10 min of hypoxia-ischemia, all reperfusion groups showed different degrees of damage. The degree of the injury increased in all the groups after 30 min of hypoxia-ischemia. Those changes include changes in the pericellular lumen, capillaries in the cortex, erythrocytes, enlarged pericellular lumen, the enlarged pericapillary lumen in the cortex, edema around glial cells, enlarged gap to form multiple necrotic foci, deformation of neurons, and loss of cell structure. The expression levels of HIF-1α, miRNA-210, and HIF-1α mRNA were higher in the hypoxic-ischemic groups than that in the control groups, among which the expression levels in the severe group were higher than that in mild group. SCN1B is down-regulated in both the mild and severe groups, and the lowest level was found at 30 min after hypoxia in both groups. MiRNA-210 plays a role in the development of hypoxic-ischemic encephalopathy (HIE) by regulating the expression changes of SCN1B. The brain tissue of fetal rats in the hypoxic-ischemic animal model showed pathological changes of brain injury.

A finTRIM Family Protein Acquires RNA-Binding Activity and E3 Ligase Activity to Shape the IFN Response in Fish

Tripartite motif (TRIM) family proteins have come forth as important modulators of innate signaling dependent on of E3 ligase activity. Recently, several human TRIM proteins have been identified as unorthodox RNA-binding proteins by RNA interactome analyses; however, their targets and functions remain largely unknown. FTRCA1 is a crucian carp (Carassius auratus)–specific finTRIM (fish novel TRIM) member and negatively regulates the IFN antiviral response by targeting two retinoic acid–inducible gene-I (RIG-I)–like receptor (RLR) pathway molecules, that is, TANK-binding kinase 1 (TBK1) and IFN regulatory factor 7 (IRF7). In this study, we identify FTRCA1 as an RNA-binding E3 ligase and characterize the contribution of its RNA-binding activity and E3 ligase activity to fish IFN response. Besides targeting TBK1 and IRF7, FTRCA1 downregulates fish IFN response also by targeting stimulator of IFN response cGAMP interactor 1 (STING1). E3 ligase activity is required for full inhibition on the TBK1- and IRF7-mediated IFN response, but partial inhibition on the STING1-mediated IFN response. However, FTRCA1 has a general binding potential to mRNAs in vitro, it selectively binds STING1 and IRF7 mRNAs in vivo to attenuate mRNA levels, and it directly interacts with TBK1 protein to target protein degradation for downregulating the IFN response. Our results present an interesting example of a fish species–specific finTRIM protein that has acquired RNA-binding activity and E3 ligase activity to fine-tune fish IFN response.

An Adenoviral Vector as a Versatile Tool for Delivery and Expression of miRNAs

Only two decades after discovering miRNAs, our understanding of the functional effects of deregulated miRNAs in the development of diseases, particularly cancer, has been rapidly evolving. These observations and functional studies provide the basis for developing miRNA-based diagnostic markers or new therapeutic strategies. Adenoviral (Ad) vectors belong to the most frequently used vector types in gene therapy and are suitable for strong short-term transgene expression in a variety of cells. Here, we report the set-up and functionality of an Ad-based miRNA vector platform that can be employed to deliver and express a high level of miRNAs efficiently. This vector platform allows fast and efficient vector production to high titers and the expression of pri-miRNA precursors under the control of a polymerase II promoter. In contrast to non-viral miRNA delivery systems, this Ad-based miRNA vector platform allows accurate dosing of the delivered miRNAs. Using a two-vector model, we showed that Ad-driven miRNA expression was sufficient in down-regulating the expression of an overexpressed and highly stable protein. Additional data corroborated the downregulation of multiple endogenous target RNAs using the system presented here. Additionally, we report some unanticipated synergistic effects on the transduction efficiencies in vitro when cells were consecutively transduced with two different Ad-vectors. This effect might be taken into consideration for protocols using two or more different Ad vectors simultaneously.

MALAT1-miRNAs network regulate thymidylate synthase and affect 5FU-based chemotherapy

Background

The active metabolite of 5-Fluorouracil (5FU), used in the treatment of several types of cancer, acts by inhibiting the thymidylate synthase encoded by the TYMS gene, which catalyzes the rate-limiting step in DNA replication. The major failure of 5FU-based cancer therapy is the development of drug resistance. High levels of TYMS-encoded protein in cancerous tissues are predictive of poor response to 5FU treatment. Expression of TYMS is regulated by various mechanisms, including involving non-coding RNAs, both miRNAs and long non-coding RNAs (lncRNAs).

Aim

To delineate the miRNAs and lncRNAs network regulating the level of TYMS-encoded protein.

Main body

Several miRNAs targeting TYMS mRNA have been identified in colon cancers, the levels of which can be regulated to varying degrees by lncRNAs. Due to their regulation by the MALAT1 lncRNA, these miRNAs can be divided into three groups: (1) miR-197-3p, miR-203a-3p, miR-375-3p which are downregulated by MALAT1 as confirmed experimentally and the levels of these miRNAs are actually reduced in colon and gastric cancers; (2) miR-140-3p, miR-330-3p that could potentially interact with MALAT1, but not yet supported by experimental results; (3) miR-192-5p, miR-215-5p whose seed sequences do not recognize complementary response elements within MALAT1. Considering the putative MALAT1-miRNAs interaction network, attention is drawn to the potential positive feedback loop causing increased expression of MALAT1 in colon cancer and hepatocellular carcinoma, where YAP1 acts as a transcriptional co-factor which, by binding to the TCF4 transcription factor/ β-catenin complex, may increase the activation of the MALAT1 gene whereas the MALAT1 lncRNA can inhibit miR-375-3p which in turn targets YAP1 mRNA.

Conclusion

The network of non-coding RNAs may reduce the sensitivity of cancer cells to 5FU treatment by upregulating the level of thymidylate synthase.

MicroRNA-Mediated Silencing Pathways in the Nervous System and Neurological Diseases

MicroRNAs (miRNAs) are small noncoding RNAs that play a prominent role in post-transcriptional gene regulation mechanisms in the brain tuning synaptic plasticity, memory formation, and cognitive functions in physiological and pathological conditions [...]

Aberrant miR-874-3p/leptin/EGFR/c-Myc signaling contributes to nasopharyngeal carcinoma pathogenesis

BACKGROUND

Leptin is important in physiological and pathological functions in various cancers, however, the significance and mechanisms of leptin in nasopharyngeal carcinoma remain ambiguous.

METHODS

Leptin expression was analyzed by QPCR, immunohistochemistry, Western blotting, and TCGA database. The impact of gain- or loss-of-function of leptin were determined by MTT, colony formation, wound healing, and Transwell assays in NPC cells, and by a xenograft tumor model. Leptin-modulated glucose consumption and lactate production were assessed by ELISA. Furthermore, leptin-regulated signaling pathways were examined by QPCR and Western blotting assays. The immunoprecipitation assay was conducted to determine interaction between leptin and EGFR. In addition, miR-874-3p-regulated leptin expression was evaluated using bioinformatics, QPCR, luciferase assay, AGO2-RIP assay, and Western blotting.

RESULTS

In this study, we found that leptin was highly expressed in the sera and tumor tissues of patients with NPC, and elevated leptin expression was associated with advanced clinical features and poor prognosis. Functional assays demonstrated that leptin remarkably promoted NPC cell growth, motility, and glycolysis in vitro and in vivo. Mechanistically, leptin associated with EGFR, resulting in enhanced cell growth through the regulation of cell-cycle related markers, glycolysis-related genes, and EGFR/AKT/c-Myc signaling. Moreover, leptin potentiated the invasive capacity of NPC cells by promoting EMT. We further explored that miR-874-3p influenced leptin-mediated NPC progression. Overexpression of miR-874-3p prevented cell growth, motility, glucose consumption, and lactate production in NPC cells, whereas miR-874-3p inhibition had the opposite effects. AGO-RIP assays confirmed that Argonaute 2 (AGO2), a protein associated with miR-874-3p, regulated leptin expression in NPC cells. The rescue assays indicated that inhibition of leptin suppressed the effects of miR-874-3p inhibitor. In clinical specimens, miR-874-3p was negatively correlated with leptin.

CONCLUSIONS

Leptin may serve as a novel prognostic factor and potential therapeutic target for patients with NPC. In addition, a newly discovered regulatory axis of leptin/EGFR/AKT/c-Myc can provide a novel therapeutic strategy for NPC.

AGO1 regulates pericentromeric regions in mouse embryonic stem cells

Argonaute proteins (AGOs), which play an essential role in cytosolic post-transcriptional gene silencing, have been also reported to function in nuclear processes like transcriptional activation or repression, alternative splicing and, chromatin organization. As most of these studies have been conducted in human cancer cell lines, the relevance of AGOs nuclear functions in the context of mouse early embryonic development remains uninvestigated. Here, we examined a possible role of the AGO1 protein on the distribution of constitutive heterochromatin in mouse embryonic stem cells (mESCs). We observed a specific redistribution of the repressive histone mark H3K9me3 and the heterochromatin protein HP1α, away from pericentromeric regions upon Ago1 depletion. Furthermore, we demonstrated that major satellite transcripts are strongly up-regulated in Ago1_KO mESCs and that their levels are partially restored upon AGO1 rescue. We also observed a similar redistribution of H3K9me3 and HP1α in Drosha_KO mESCs, suggesting a role for microRNAs (miRNAs) in the regulation of heterochromatin distribution in mESCs. Finally, we showed that specific miRNAs with complementarity to major satellites can partially regulate the expression of these transcripts.

LINC00473-modified bone marrow mesenchymal stem cells incorporated thermosensitive PLGA hydrogel transplantation for steroid-induced osteonecrosis of femoral head: A detailed mechanistic study and validity evaluation

The pathogenesis of steroid-induced osteonecrosis of the femoral head (SONFH) involves a glucocorticoid-induced imbalance of osteogenic and adipogenic differentiation, and apoptosis of bone marrow mesenchymal stem cells (BMSCs). An increasing number of genes, especially noncoding RNAs, have been implicated in the function of BMSCs. Our previous studies have confirmed the key role of LINC00473 and miR-23a-3p on the osteogenic, adipogenic differentiation, and apoptosis of BMSCs. However, the underlying mechanism of this process is still unclear. Based on bioinformatics analysis, here we investigated the effects of LINC00473 on the LRP5/Wnt/β-catenin signaling pathway in the osteogenesis and adipogenesis of BMSCs, as well as the PEBP1/Akt/Bad/Bcl-2 signaling pathway in dexamethasone- (Dex-) induced apoptosis of BMSCs. Our data showed that LINC00473 could promote osteogenesis and suppress the adipogenesis of BMSCs through the activation of the miR-23a-3p/LRP5/Wnt/β-catenin signaling pathway axis, while rescuing BMSCs from Dex-induced apoptosis by activating the miR-23a-3p/PEBP1/Akt/Bad/Bcl-2 signaling pathway axis. Notably, we observed that LINC00473 interacted with miR-23a-3p in an Argonaute 2 (AGO2)-dependent manner based on dual-luciferase reporter assay, AGO2-related RNA immunoprecipitation, and RNA antisense purification assay. Furthermore, injectable thermosensitive polylactic-co-glycolic acid (PLGA) hydrogel loaded with rat-derived BMSCs (rBMSCs) modified by LINC00473 were used for the treatment of SONFH in a rat model. Our results demonstrated that PLGA hydrogels provided a suitable environment for harboring rBMSCs. Besides, transplantation of PLGA hydrogels loaded with rBMSCs modified by LINC00473 could significantly promote the bone repair and reconstruction of the necrotic area at the femoral head in our SONFH rat model. Surprisingly, compared with the transplantation of BMSCs alone, the transplanted rBMSCs encapsulated within the PLGA hydrogel could migrate from the medullary cavity to the femoral head. In summary, LINC00473 promoted osteogenesis, inhibited adipogenesis, and antagonized Dex-induced apoptosis of BMSCs. Therefore, LINC00473 could provide a new strategy for the treatment of SONFH.

Silencing of Ago-2 Interacting Protein SERBP1 Relieves KCC2 Repression by miR-92 in Neurons

RNA-binding proteins (RBPs) play important roles in modulating miRNA-mediated mRNA target repression. Argonaute2 (Ago2) is an essential component of the RNA-induced silencing complex (RISC) that plays a central role in silencing mechanisms via small non-coding RNA molecules known as siRNAs and miRNAs. Small RNAs loaded into Argonaute proteins catalyze endoribonucleolytic cleavage of target RNAs or recruit factors responsible for translational silencing and mRNA target destabilization. In previous studies we have shown that KCC2, a neuronal Cl (-) extruding K (+) Cl (-) co-transporter 2, is regulated by miR-92 in neuronal cells. Searching for Ago2 partners by immunoprecipitation and LC-MS/MS analysis, we isolated among other proteins the Serpine mRNA binding protein 1 (SERBP1) from SH-SY5Y neuroblastoma cells. Exploring the role of SERBP1 in miRNA-mediated gene silencing in SH-SY5Y cells and primary hippocampal neurons, we demonstrated that SERBP1 silencing regulates KCC2 expression through the 3' untranslated region (UTR). In addition, we found that SERBP1 as well as Ago2/miR-92 complex bind to KCC2 3'UTR. Finally, we demonstrated the attenuation of miR-92-mediated repression of KCC2 3'UTR by SERBP1 silencing. These findings advance our knowledge regarding the miR-92-mediated modulation of KCC2 translation in neuronal cells and highlight SERBP1 as a key component of this gene regulation.

MiR-21-5p-expressing bone marrow mesenchymal stem cells alleviate myocardial ischemia/reperfusion injury by regulating the circRNA_0031672/miR-21-5p/programmed cell death protein 4 pathway

BACKGROUND

For patients with coronary heart disease, reperfusion treatment strategies are often complicated by ischemia/reperfusion (I/R) injury (IRI), leading to serious organ damage and malfunction. The miR-21/programmed cell death protein 4 (PDCD4) pathway is involved in the IRI of cardiomyocytes; however, the aberrant miR-21 expression remains unexplained. Therefore, this study aimed to explore whether circRNA_0031672 downregulates miR-21-5p expression during I/R and to determine whether miR-21-5p-expressing bone marrow mesenchymal stem cells (BMSCs) reduce myocardial IRI.

METHODS

CircRNA_0031672, miR-21-5p, and PDCD4 expressions were evaluated in the I/R rat model and hypoxia/re-oxygenation (H/R)-treated H9C2 cells. Their interactions were subsequently investigated using luciferase reporter and RNA pulldown assays. Methyltransferase-like 3, a methyltransferase catalyzing N6-methyladenosine (m6A), was overexpressed in H9C2 cells to determine whether m6A modification influences miR-21-5p targeting PDCD4. BMSCs stably expressing miR-21 were co-cultured with H9C2 cells to investigate the protective effect of BMSCs on H9C2 cells upon H/R.

RESULTS

I/R downregulated miR-21-5p expression and upregulated circRNA_0031672 and PDCD4 expressions. CircRNA_0031672 knockdown increased miR-21-5p expression, but repressed PDCD4 expression, indicating that circRNA_0031672 competitively bound to miR-21-5p and prevented it from targeting PDCD4 mRNA. The m6A modification regulated PDCD4 expression, but had no effect on miR-21-5p targeting PDCD4. The circRNA_0031672/miR-21-5p/PDCD4 axis regulated myocardial cells viability and apoptosis after H/R treatment; co-culture with miR-21-5p-expressing BMSCs restored miR-21-5p abundance in H9C2 cells and further reduced H9C2 cells apoptosis induced by H/R.

CONCLUSIONS

We identified a novel circRNA_0031672/miR-21-5p/PDCD4 signaling pathway that mediates the apoptosis of cardiomyocytes and successfully alleviates IRI in myocardial cells by co-culture with miR-21-5p-expressing BMSCs, offering novel insights into the IRI pathogenesis in cardiovascular diseases.

YTHDF1 promotes mRNA degradation via YTHDF1-AGO2 interaction and phase separation

Objectives

YTHDF1 is known as a m⁶A reader protein, and many researches of YTHDF1 focused on the regulation of mRNA translation efficiency. However, YTHDF1 is also related to RNA degradation, but how YTHDF1 regulates mRNA degradation is indefinite. Liquid‐liquid phase separation (LLPS) underlies the formation of membraneless compartments in mammal cells, and there are few reports focused on the correlation of RNA degradation with LLPS. In this research, we focused on the mechanism of YTHDF1 degraded mRNA through LLPS.

Materials and Methods

The CRISPR/Cas9 knock out system was used to establish the YTHDF1 knock out (YTHDF1‐KO) cell lines (HEK293 and HeLa) and METTL14 knock out (METTL14‐KO) cell line (HEK293). 4SU‐TT‐seq was used to check the half‐life changes of mRNAs. Actinomycin D and qPCR were used to test the half‐life changes of individual mRNA. RNA was stained with SYTO RNA‐select dye in wild type (WT) and YTHDF1‐KO HeLa cell lines. Co‐localization of YTHDF1 and AGO2 was identified by immunofluorescence. The interaction domain of YTHDF1 and AGO2 was identified by western blot. Phase separation of YTHDF1 was performed in vitro and in vivo. Fluorescence recovery after photobleaching (FRAP) was performed on droplets as an assessment of their liquidity.

Results

In this research, we found that deletion of YTHDF1 led to massive RNA patches deposited in cytoplasm. The results of 4SU‐TT‐seq showed that deletion of YTHDF1 would prolong the half‐life of mRNAs. Immunofluorescence data showed that YTHDF1 and AGO2 could co‐localize in P‐body, and Co‐IP results showed that YTHDF1 could interact with AGO2 through YT521‐B homology (YTH) domain. We confirmed that YTHDF1 could undergo phase separation in vitro and in vivo, and compared with AGO2, YTHDF1 was more important in P‐body formation. The FRAP results showed that liquid AGO2 droplets would convert to gel/solid when YTHDF1 was deleted. As AGO2 plays important roles in miRISCs, we also found that miRNA‐mediate mRNA degradation is related to YTHDF1.

Conclusions

YTHDF1 recruits AGO2 through the YTH domain. YTHDF1 degrades targeting mRNAs by promoting P‐body formation through LLPS. The deletion of YTHDF1 causes the P‐body to change from liquid droplets to gel/solid droplets, and form AGO2/RNA patches, resulting in a degradation delay of mRNAs. These findings reveal a previously unrecognized crosstalk between YTHDF1 and AGO2, raising a new sight of mRNA post‐transcriptional regulation by YTHDF1.

Localization and Functional Roles of Components of the Translation Apparatus in the Eukaryotic Cell Nucleus

Components of the translation apparatus, including ribosomal proteins, have been found in cell nuclei in various organisms. Components of the translation apparatus are involved in various nuclear processes, particularly those associated with genome integrity control and the nuclear stages of gene expression, such as transcription, mRNA processing, and mRNA export. Components of the translation apparatus control intranuclear trafficking; the nuclear import and export of RNA and proteins; and regulate the activity, stability, and functional recruitment of nuclear proteins. The nuclear translocation of these components is often involved in the cell response to stimulation and stress, in addition to playing critical roles in oncogenesis and viral infection. Many components of the translation apparatus are moonlighting proteins, involved in integral cell stress response and coupling of gene expression subprocesses. Thus, this phenomenon represents a significant interest for both basic and applied molecular biology. Here, we provide an overview of the current data regarding the molecular functions of translation factors and ribosomal proteins in the cell nucleus.

Human exposure to low dose ionizing radiation affects miR-21 and miR-625 expression levels

BACKGROUND

Recently exposure to ionizing radiation driven by artificial radiation sources such as Medical X-rays and Nuclear medicine has increased hastily. Ionizing radiation-induced the DNA damage and activate the DNA damage response signaling pathways. The aim of this study was to evaluate the role of miR-21 and miR-625 in response to low-dose ionizing radiation.

MATERIALS AND METHODS

In this study, the blood sample of 38 volunteer patients who underwent Cardiac scans before and after ^99mTc-MIBI injection were used. The WBC of patients was used for RNA extraction and after cDNA synthesis by the poly-A method the expression level of miR-21 and miR-625 was evaluated by real-time PCR method.

RESULTS

The results of this study indicated that miR-21 and miR- 625 were significantly upregulated under exposure to low-dose ionizing radiation. The expression level of these miRNAs was not significantly correlated with the age and BMI of patients. More ever the bioinformatics analysis indicated that SP1 was a common target of both miRNAs and had the highest degree between hub genes.

CONCLUSION

In summary miR-21 and miR-625 can contribute to the response to acute low dose ionizing radiation by targeting the SP1. However further studies should be carried out on the molecular mechanism of effects of miR-21 and miR-625 in response to low dose ionizing radiation by targeting the SP1.

Unexpected Implication of SRP and AGO2 in Parkinson's Disease: Involvement in Alpha-Synuclein Biogenesis

Parkinson's disease (PD) is a neurodegenerative disorder classified by the loss of dopaminergic neurons in the substantia nigra pars compacta, the region of the brain that is responsible for motor control. Surviving neurons in this region contain aggregated protein alpha-Synuclein (αSyn) in the form of cytoplasmic inclusions, referred to as Lewy bodies. Changes in αSyn expression are also associated with PD and its progression. Previously, we demonstrated that signal recognition particle (SRP) and Argonaute 2 (AGO2) proteins are involved in protein quality control at the ribosome during translation. We also demonstrated that SRP has an mRNA protection function in addition to a protein targeting function, thus controlling mRNA and protein expression. In this study, we tested involvement of these factors in αSyn biogenesis. We hypothesize that loss of these factors may interfere with αSyn expression, and subsequently, be associated with PD. Using depletion assays in human cell culture and analysis of these proteins in the brains of deceased PD patients, we demonstrate that SRP and AGO2 are involved in the control of αSyn expression and AGO2 has reduced expression in PD. We show for the first time that SRP is involved in mRNA protection of αSyn, a protein that does not have a signal sequence or transmembrane span. Our findings suggest that SRP may interact with a hydrophobic domain in the middle of αSyn during translation. Understanding the molecular mechanisms controlling αSyn biogenesis in cells is vital to developing preventative therapies against PD.

The long non-coding RNA NNT-AS1 promotes clear cell renal cell carcinoma progression via regulation of the miR-137/ Y-box binding protein 1 axis

Long noncoding RNAs (lncRNAs) have been implicated in the progression of malignant tumors, including in clear cell renal cell carcinoma (ccRCC). However, the function and the specific mechanism of lncRNA nicotinamide nucleotide transhydrogenase antisense RNA 1 (NNT-AS1) in ccRCC remains unknown. Thus, this study explored the role of NNT-AS1 in ccRCC. We evaluated NNT-AS1 expression in ccRCC specimens. Next, CCK-8 and Transwell assays were used to evaluate cell proliferation and metastatic abilities. The interaction between miR-137 and NNT-AS1 or Y-box binding protein 1 (YBX-1) was confirmed using a dual luciferase reporter assay. The results showed that NNT-AS1 was significantly upregulated in ccRCC specimens compared with normal tissues. Inhibition of NNT-AS1 restrained ccRCC proliferation and metastasis. Mechanistically, NNT-AS1 acted as a competitive endogenous RNA to sponge miR-137, which depressed ccRCC cells proliferation and metastasis. Moreover, with the use of bioinformatics analysis, the famous oncogene YBX-1 was selected as the potential target of miR-137. Luciferase assay also confirmed the interaction between miR-137 and YBX-1. Further functional studies demonstrated that the inhibition effect of NNT-AS1 knockdown on ccRCC carcinogenesis could be partially reversed by overexpression of YBX-1, suggesting that NNT-AS1 promotes ccRCC progression through the miR-137/YBX-1 pathway. In summary, these findings indicate that NNT-AS1 promotes ccRCC progression via the miR-137/YBX-1 pathway, which may provide a promising therapeutic target for renal cell carcinoma.

p53 mRNA Metabolism Links with the DNA Damage Response

Human cells are subjected to continuous challenges by different genotoxic stress attacks. DNA damage leads to erroneous mutations, which can alter the function of oncogenes or tumor suppressors, resulting in cancer development. To circumvent this, cells activate the DNA damage response (DDR), which mainly involves cell cycle regulation and DNA repair processes. The tumor suppressor p53 plays a pivotal role in the DDR by halting the cell cycle and facilitating the DNA repair processes. Various pathways and factors participating in the detection and repair of DNA have been described, including scores of RNA-binding proteins (RBPs) and RNAs. It has become increasingly clear that p53's role is multitasking, and p53 mRNA regulation plays a prominent part in the DDR. This review is aimed at covering the p53 RNA metabolism linked to the DDR and highlights the recent findings.

Specific and sensitive detection of CircRNA based on netlike hybridization chain reaction

Circular RNA (circRNA), as a new class of biomarker, plays an important role in the occurrence and development of cancer. However, the limitations of detection methods in recent years have severely restricted the related research of circRNA. Here, we have developed an effective circRNA detection method based on the thermostatic netlike hybridization chain reaction (HCR). It combines reverse transcription-rolling circle amplification (RT-RCA) with well-designed netlike HCR to achieve dual selection and dual signal amplification, which can eliminate the interference of linear isomers. This two-dimensional netlike HCR is composed of an ingeniously designed trigger chain and two hairpin fuel probes, which can generate a stable network structure with RT-RCA products containing multiple sets of repeats at a constant temperature, thereby producing enhanced fluorescent signals. Systematic studies reveal that the optimized netlike HCR system has higher detection efficiency for DNA strands containing multiple sets of repetitive sequences, can detect circRNA as low as 0.1 pM, and has excellent selectivity. By using human tumor cell lines and tissues, it has been verified that the netlike HCR-based method can accurately detect specific circRNA in real biological samples without RNase R enrichment, which provides a simple and useful platform for detecting low-abundance circRNA. Furthermore, the proposed strategy is also a potential method for detecting some genes containing repetitive sequences, such as telomere DNA, centromere DNA and ribosomal DNA (rDNA).

LncRNA HOXA-AS2 Activates the Notch Pathway to Promote Cervical Cancer Cell Proliferation and Migration

Long non-coding RNAs (lncRNAs) are crucial participants in cancer development. HOXA cluster antisense RNA 2 (HOXA-AS2) plays a tumor promoter role in bladder cancer. However, the functional role of HOXA-AS2 in cervical cancer remains unclear. Our study first found that HOXA-AS2 expression was up-regulated in cervical cancer cells. Then functional analysis including cell counting kit-8 (CCK-8), colony formation, transwell, and wound healing uncovered that reduction of HOXA-AS2 remarkably impeded cell proliferation and migration in cervical cancer. Additionally, luciferase reporter assays were performed to confirm that HOXA-AS2 activated Notch signaling pathway via the mediation of independent recombination signal binding protein for JK (RBP-JK) activity. As we know, Notch intracellular domain (NICD) is associated with RBP-JK in the nucleus to promote target genes in the Notch pathway. Through RNA immunoprecipitation (RIP), RNA pull down, and fluorescent in situ hybridization (FISH) assays, we observed that HOXA-AS2 combined with NICD. Moreover, the data from Co-IP assays indicated that HOXA-AS2 reduction weakened the interaction of NICD and RBP-JK. Collectively, HOXA-AS2 played a cancer-promoting role in cervical cancer development by modulating the Notch pathway, which might become a novel target for cervical cancer treatment.

DDX21 interacts with nuclear AGO2 and regulates the alternative splicing of SMN2

AGO2 is the only member of mammalian Ago protein family that possesses the catalytic activity and plays a central role in gene silencing. Recently researches reported that multiple gene silencing factors, including AGO2, function in the nuclei. The molecular mechanisms of the gene silencing factors functioning in nuclei are conducive to comprehend the roles of gene silencing in pretranslational regulation of gene expression. Here, we report that AGO2 interacts with DDX21 indirectly in an RNA-dependent manner by Co-IP and GST-Pulldown assays and the 2 proteins present nuclei foci in the immunofluorescence experiments. We found that DDX21 up-regulated the protein level of AGO2 and participated in target gene, SNM2, alternative splicing involved in AGO2 by the indirect interaction with AGO2, which produced different transcripts of SMN2 in discrepant expression level. This study laid important experiment foundation for the further analysis of the nuclear functions of gene silencing components.

LncRNA ST7-AS1, by regulating miR-181b-5p/KPNA4 axis, promotes the malignancy of lung adenocarcinoma

Background

Growing evidence suggests that suppressor of tumorigenicity 7 antisense RNA 1 (ST7-AS1) is an oncogenic long noncoding RNA (lncRNA). However, little is known on its clinical significance, biological functions, or molecular mechanisms in lung adenocarcinoma (LUAD).

Methods

The expression of ST7-AS1 and miR-181b-5p were examined by qRT-PCR. The correlations between ST7-AS1 level and different clinicopathological features were analysed. In vitro, LUAD cells were examined for cell viability, migration and invasion by MTT, wound healing and Transwell assay, respectively. Epithelial-mesenchymal transition (EMT) biomarkers were detected by Western blot. The regulations between ST7-AS1, miR-181b-5p, and KPNA4 were examined by luciferase assay, RNA immunoprecipitation, RNA pulldown. Both gain- and loss-of-function strategies were used to assess the importance of different signalling molecules in malignant phenotypes of LUAD cells. The in vivo effect was analysed using the xenograft and the experimental metastasis mouse models.

Results

ST7-AS1 was upregulated in LUAD tissues or cell lines, correlated with tumours of positive lymph node metastasis or higher TNM stages, and associated with shorter overall survival of LUAD patients. ST7-AS1 essentially maintained the viability, migration, invasion, and EMT of LUAD cells. The oncogenic activities of ST7-AS1 were accomplished by sponging miR-181b-5p and releasing the suppression of the latter on KPNA4. In LUAD tissues, ST7-AS1 level positively correlated with that of KPNA4 and negatively with miR-181b-5p level. In vivo, targeting ST7-AS1 significantly inhibited xenograft growth and metastasis.

Conclusions

ST7-AS1, by regulating miR-181b-5p/KPNA4 axis, promotes the malignancy of LUAD cells. Targeting ST7-AS1 and KPNA4 or up-regulating miR-181b-5p, therefore, may benefit the treatment of LUAD.

TRIM29 inhibits miR-873-5P biogenesis via CYTOR to upregulate fibronectin 1 and promotes invasion of papillary thyroid cancer cells

Papillary thyroid cancer (PTC) is the most common endocrine tumor with an increasing incidence, has a strong propensity for neck lymph node metastasis. Limited treatment options are available for patients with advanced or recurrent metastatic disease, resulting in a poor prognosis. Tripartite motif protein 29 (TRIM29) is dysregulated in various cancer and functions as oncogene or tumor suppressor in discrete cancers. In this study, we found that both TRIM29 and fibronectin 1 (FN1) were upregulated with positive correlation in PTC tissues. Neither overexpression nor downregulation of TRIM29 altered the proliferation of PTC cells significantly. Overexpression of TRIM29 significantly promotes, while knockdown of TRIM29 significantly decreases migration and invasion by regulating FN1 expression in PTC cells. In terms of mechanism, we found that TRIM29 altered the stability of FN1 mRNA via regulation of miR-873-5p expression. The current study also demonstrated that long non-coding RNA (LncRNA) CYTOR suppressed maturation of miR-873-5p via interaction with premiR-873, and TRIM29 decreased miR-873-5p via upregulation of CYTOR. This study suggests that involvement of TRIM29 in migration and invasion in PTC cells may reveal potential metastatic mechanism of PTC and represent a novel therapeutic target and strategy.

Diverse Defenses: A Perspective Comparing Dipteran Piwi-piRNA Pathways

Animals face the dual threat of virus infections hijacking cellular function and transposons proliferating in germline genomes. For insects, the deeply conserved RNA interference (RNAi) pathways and other chromatin regulators provide an important line of defense against both viruses and transposons. For example, this innate immune system displays adaptiveness to new invasions by generating cognate small RNAs for targeting gene silencing measures against the viral and genomic intruders. However, within the Dipteran clade of insects, Drosophilid fruit flies and Culicids mosquitoes have evolved several unique mechanistic aspects of their RNAi defenses to combat invading transposons and viruses, with the Piwi-piRNA arm of the RNAi pathways showing the greatest degree of novel evolution. Whereas central features of Piwi-piRNA pathways are conserved between Drosophilids and Culicids, multiple lineage-specific innovations have arisen that may reflect distinct genome composition differences and specific ecological and physiological features dividing these two branches of Dipterans. This perspective review focuses on the most recent findings illuminating the Piwi/piRNA pathway distinctions between fruit flies and mosquitoes, and raises open questions that need to be addressed in order to ameliorate human diseases caused by pathogenic viruses that mosquitoes transmit as vectors.

Role of cereblon in angiogenesis and in mediating the antiangiogenic activity of immunomodulatory drugs

Cereblon (CRBN) is a substrate recruiter element of the E3 cullin 4-RING ubiquitin ligase complex, and a binding target of immunomodulatory agents (IMiDs). CRBN is responsible for the pleiotropic effects of IMiDs, yet its function in angiogenesis and in mediating the antiangiogenic effects of IMiDs remains unclear. We investigated the role of CRBN in the angiogenic process and in propagating the antiangiogenic effects of IMiDs in vitro. siRNA-mediated CRBN knock down in human endothelial cells (HUVEC and HMVEC-L), did not affect endothelial cell proliferation, migration, or tube formation. Using CRBN-deficient mice, we further demonstrated that microvessal formation can occur independently of cereblon in the ex vivo mouse aortic ring model. The cereblon E3 ubiquitin ligase complex can recruit endothelial cell-specific factors, AGO2 (associated with angiogenesis), and SALL4 (associated with embryogenesis/angiogenesis), for ubiquitin-mediated degradation. Knockdown of CRBN caused a corresponding increase in AGO2 and SALL4 protein expression and IMiD treatment was able to rescue the siCRBN effect to increase the CRBN expression. These findings suggest one potential mechanism of action that likely involves a tightly coordinated regulation of CRBN with endothelial cell targets and highlight the need to further elucidate the mechanism(s), which could include cereblon-independent pathways, through which IMiDs exert their antiangiogenic effects.