RNAa in action: from the exception to the norm

Tetramethylpyrazine ameliorates LPS-induced acute lung injury via the miR-369-3p/DSTN axis

Acute lung injury (ALI) is a severe clinical respiratory condition characterized by high rates of mortality and morbidity, for which effective treatments are currently lacking. In this study, lipopolysaccharide (LPS) was used to induce ALI mice, demonstrating the efficacy of tetramethylpyrazine (TMP) in ameliorating ALI. Subsequent we perfored high-throughput sequencing analysis and used Targetscan 8.0 and miRWalk 3.0 databases to predict the interaction between microRNAs and destrin (DSTN), ultimately identifying miR-369-3p as the focus of the investigation. The adenovirus carrying miR-369-3p was administered one week prior to LPS-induced in order to assess its potential efficacy in ameliorating ALI in mice. The findings indicated that the overexpression of miR-369-3p resulted in enhanced lung function, reduced pulmonary edema, inflammation, and permeability in LPS-induced ALI mice, while the suppression of miR-369-3p exacerbated the damage in these mice. Furthermore, the beneficial effects of TMP on LPS-induced ALI were negated by the downregulation of miR-369-3p. The results of our study demonstrate that TMP mitigates LPS-induced ALI through upregulation of miR-369-3p. Consequently, the findings of this study advocate for the clinical utilization of TMP in ALI treatment, with miR-369-3p emerging as a promising target for future ALI interventions.

PPFIA1-targeting miR-181a mimic and saRNA overcome imatinib resistance in BCR-ABL1-independent chronic myeloid leukemia by suppressing leukemia stem cell regeneration

A large proportion of patients with chronic myeloid leukemia (CML; 20%-50%) develop resistance to imatinib in a BCR-ABL1-independent manner. Therefore, new therapeutic strategies for use in this subset of imatinib-resistant CML patients are urgently needed. In this study, we used a multi-omics approach to show that PPFIA1 was targeted by miR-181a. We demonstrate that both miR-181a and PPFIA1-siRNA reduced the cell viability and proliferative capacity of CML cells in vitro, as well as prolonged the survival of B-NDG mice harboring human BCR-ABL1-independent imatinib-resistant CML cells. Furthermore, treatment with miR-181a mimic and PPFIA1-siRNA inhibited the self-renewal of c-kit+ and CD34+ leukemic stem cells and promoted their apoptosis. Small activating (sa)RNAs targeting the promoter of miR-181a increased the expression of endogenous primitive miR-181a (pri-miR-181a). Transfection with saRNA 1-3 inhibited the proliferation of imatinib-sensitive and -resistant CML cells. However, only saRNA-3 showed a stronger and more sustained inhibitory effect than the miR-181a mimic. Collectively, these results show that miR-181a and PPFIA1-siRNA may overcome the imatinib resistance of BCR-ABL1-independent CML, partially by inhibiting the self-renewal of leukemia stem cells and promoting their apoptosis. Moreover, exogenous saRNAs represent promising therapeutic agents in the treatment of imatinib-resistant BCR-ABL1-independent CML.

Further Insights on RNA Expression and Sperm Motility

Asthenozoospermia is one of the main causes of male infertility and it is characterized by reduced sperm motility. Several mutations in genes that code for structural or functional constituents of the sperm have already been identified as known causes of asthenozoospermia. In contrast, the role of sperm RNA in regulating sperm motility is still not fully understood. Consequently, here we aim to contribute to the knowledge regarding the expression of sperm RNA, and ultimately, to provide further insights into its relationship with sperm motility. We investigated the expression of a group of mRNAs by using real-time PCR (CATSPER3, CFAP44, CRHR1, HIP1, IQCG KRT34, LRRC6, QRICH2, RSPH6A, SPATA33 and TEKT2) and the highest score corresponding to the target miRNA for each mRNA in asthenozoospermic and normozoospermic individuals. We observed a reduced expression of all mRNAs and miRNAs in asthenozoospermic patients compared to controls, with a more accentuated reduction in patients with progressive sperm motility lower than 15%. Our work provides further insights regarding the role of RNA in regulating sperm motility. Further studies are required to determine how these genes and their corresponding miRNA act regarding sperm motility, particularly KRT34 and CRHR1, which have not previously been seen to play a significant role in regulating sperm motility.

Transcriptional regulation of nuclear miRNAs in tumorigenesis (Review)

MicroRNAs (miRNAs/miRs) are a type of endogenous non‑coding small RNA that regulates gene expression. miRNAs regulate gene expression at the post‑transcriptional level by targeting the 3'‑untranslated region (3'UTR) of cytoplasmic messenger RNAs (mRNAs). Recent research has confirmed the presence of mature miRNAs in the nucleus, which bind nascent RNA transcripts, gene promoter or enhancer regions, and regulate gene expression via epigenetic pathways. Some miRNAs have been shown to function as oncogenes or tumor suppressor genes by modulating molecular pathways involved in human cancers. Notably, a novel molecular mechanism underlying the dysregulation of miRNA expression in cancer has recently been discovered, indicating that miRNAs may be involved in tumorigenesis via a nuclear function that influences gene transcription and epigenetic states, elucidating their potential therapeutic implications. The present review article discusses the import of nuclear miRNAs, nucleus‑cytoplasm transport mechanisms and the nuclear functions of miRNAs in cancer. In addition, some software tools for predicting miRNA binding sites are also discussed. Nuclear miRNAs supplement miRNA regulatory networks in cancer as a non‑canonical aspect of miRNA action. Further research into this aspect may be critical for understanding the role of nuclear miRNAs in the development of human cancers.

SPOP Inhibition of Endometrial Carcinoma and Its Clinicopathological Relationship

Objective

Endometrial carcinoma (EC) ranks first in the incidence of female genital malignancies in developed countries. SPOP (speckle-type POZ protein) has changed in EC with a statistically high frequency. This research may play a crucial role in the initiation and progression of EC, ultimately leading to fresh therapeutic targets. Explore the expression of SPOP in EC; observe its effect on the proliferation, invasion, and migration of EC cells after upregulating the expression of SPOP through RNA activation.

Methods

The expression levels of SPOP protein in 150 EC tissues and 45 normal endometrial tissues were detected by immunohistochemistry and Western blotting. Analyze the relationship between SPOP expression and clinicopathological characteristics. The differences of the proliferation, migration, and invasion abilities between before and after transfection were analyzed using CCK-8 and Transwell assays.

Results

The results of immunohistochemistry and Western blotting showed the expression level of SPOP in EC tissue significantly reduced or even missed compared with normal endometrial tissue. The results of CCK-8 showed that the growth of EC significantly slowed down after the upregulating of SPOP expression. The results of the Transwell assay showed the migration and invasion abilities of EC cells were weakened after the level of SPOP was upregulated.

Conclusions

The expression level of SPOP in EC tissues is lower and related to the clinicopathological features compared with normal endometrial tissues. After upregulating the SPOP expression by RNA activation in EC cell lines, the abilities of proliferation, migration, and invasion of cells were significantly inhibited.

Let-7c increases BACE2 expression by RNAa and decreases Aβ production

MicroRNAs (miRNAs) are highly conserved, non-coding transcripts that regulate gene expression in various ways. Evidence suggests that miRNAs may be a contributory factor in neurodegeneration, including Alzheimer's disease (AD), Parkinson's disease (PD), and triplet repeat disorders. In order to further understand the potential roles of miRNAs in the pathogenesis of AD, we analyzed Down syndrome (DS), a special model of AD, by using a TaqMan microRNA array and found that miRNA let-7c was up-regulated in both DS and AD. ELISA assay showed that let-7c reduced the expression level of Aβ significantly. Real-time quantitative-polymerase chain reaction (RT-qPCR) was conducted to reveal that the expression level of let-7c increased dramatically in DS cells, patients with DS and mice with AD compared with normal ones respectively. Additionally, western blotting illustrated that let-7c suppressed the expression of Aβ by inducing BACE2 to cut C99 and increase the content of C83/80. BACE2 expression was inhibited by let-7c and luciferase reporter gene assay revealed that let-7c increased the activity of wild-type BACE2 promoter but not 3'UTR. Furthermore, promoter analysis of BACE2 confirmed that let-7c could bind to BACE2 in the sequence between -1368 and -1347. In addition, immunoblotting assay demonstrated that let-7c induced BACE2 expression by RNAa. To the best of our knowledge, our study revealed for the first time that let-7c up-regulated BACE2 expression and decreased Aβ production.

Visualization of subdiffusive sites in a live single cell

We measured anomalous diffusion in human prostate cancer cells which were transfected with the Alexa633 fluorescent RNA probe and co-transfected with enhanced green fluorescent protein-labeled argonaute2 protein by laser scanning microscopy. The image analysis arose from diffusion based on a “two-level system”. A trap was an interaction site where the diffusive motion was slowed down. Anomalous subdiffusive spreading occurred at cellular traps. The cellular traps were not immobile. We showed how the novel analysis method of imaging data resulted in new information about the number of traps in the crowded and heterogeneous environment of a single human prostate cancer cell. The imaging data were consistent with and explained by our modern ideas of anomalous diffusion of mixed origins in live cells. Our original research presented in this study is significant as we obtained a complex diffusion mechanism in live single cells.

Polymeric delivery systems for nucleic acid therapeutics: Approaching the clinic

Gene therapy using nucleic acids has many clinical applications for the treatment of diseases with a genetic origin as well as for the development of innovative vaccine formulations. Since nucleic acids in their free form are rapidly degraded by nucleases present in extracellular matrices, have poor pharmacokinetics and hardly pass cellular membranes, carrier systems are required. Suitable carriers that protect the nucleic acid payload against enzymatic attack, prolong circulation time after systemic administration and assist in cellular binding and internalization are needed to develop nucleic acid based drug products. Viral vectors have been investigated and are also clinically used as delivery vehicles. However, some major drawbacks are associated with their use. Therefore there has been substantial attention on the use of non-viral carrier systems based on cationic lipids and polymers. This review focuses on the properties of polymer-based nucleic acid formulations, also referred as polyplexes. Different polymeric systems are summarized, and the cellular barriers polyplexes encounter and ways to tackle these are discussed. Finally attention is given to the clinical status of non-viral nucleic acid formulations.

Exosome-transmitted microRNA-133b inhibited bladder cancer proliferation by upregulating dual-specificity protein phosphatase 1

Bladder Cancer (BC) is the ninth most common tumor in the world and one of the most common malignant tumors of the urinary system. Some studies reported that miR‐133b expression is reduced in BC, but whether it plays a role in the development of BC and its mechanism is unclear. microRNAs can be packaged into exosomes to mediate communication between tumor cells, affecting their proliferation and apoptosis. The objective of this study was to investigate the effect of exosomal miR‐133b on BC proliferation and its molecular mechanism. Firstly, the expression of miR‐133b was evaluated in BC and adjacent normal tissues, as well as in serum exosomes of BC patients and healthy controls. Then the delivery and internalization of exosomes in cells was observed through fluorescence localization. Cell viability and apoptosis were assessed in BC cells transfected with mimics and incubated with exosomes. The role of exosomal miR‐133b was also analyzed in nude mice transplant tumors. Furthermore, the target gene of miR‐133b was predicted through bioinformatics. The level of miR‐133b was significantly decreased in BC tissues and in exosomes from serum of patients, which was correlated with poor overall survival in TCGA. Exosomal miR‐133b could be obtained using BC cells after transfection with miR‐133b mimics. The miR‐133b expression increased after incubation with exosomal miR‐133b, which lead to the inhibition of viability and increase of apoptosis in BC cells. Exosomal miR‐133b could suppress tumor growth in vivo. In addition, we found that exosomal miR‐133b may play a role in suppressing BC proliferation by upregulating dual‐specificity protein phosphatase 1 (DUSP1). These findings may offer promise for new therapeutic directions of BC.

Developing small activating RNA as a therapeutic: current challenges and promises

RNA activation (RNAa) allows specific gene upregulation mediated by a small activating RNA (saRNA). Harnessing this process would help in developing novel therapeutics for undruggable diseases. Since its discovery in mid 2000s, improvements of saRNA design, synthetic chemistry and understanding of the biology have matured the way to apply RNAa. Indeed, MiNA therapeutics Ltd has conducted the first RNAa clinical trial for advanced hepatocellular carcinoma patients with promising outcomes. However, to fully realize the RNAa potential better saRNA delivery strategies are needed to target other diseases. Currently, saRNA can be delivered in vivo by lipid nanoparticles, dendrimers, lipid and polymer hybrids and aptamers. Further developing these delivery technologies and novel application of RNAa will prove to be invaluable for new treatment development.

MicroRNAs as Emerging Regulators of Signaling in the Tumor Microenvironment

A myriad of signaling molecules in a heuristic network of the tumor microenvironment (TME) pose a challenge and an opportunity for novel therapeutic target identification in human cancers. MicroRNAs (miRs), due to their ability to affect signaling pathways at various levels, take a prominent space in the quest of novel cancer therapeutics. The role of miRs in cancer initiation, progression, as well as in chemoresistance, is being increasingly investigated. The canonical function of miRs is to target mRNAs for post-transcriptional gene silencing, which has a great implication in first-order regulation of signaling pathways. However, several reports suggest that miRs also perform non-canonical functions, partly due to their characteristic non-coding small RNA nature. Examples emerge when they act as ligands for toll-like receptors or perform second-order functions, e.g., to regulate protein translation and interactions. This review is a compendium of recent advancements in understanding the role of miRs in cancer signaling and focuses on the role of miRs as novel regulators of the signaling pathway in the TME.

MicroRNAs mediate the anti-tumor and protective effects of ginsenosides

MicroRNAs (miRs(, as short non-coding RNAs, regulate important biological processes and mainly are associated with regulation of gene expression. The miRs are beneficial targets for diagnosis of various disorders, particularly cancer, since their expression profile undergoes alterations in pathological conditions. The numerous drugs have been designed with the capability of targeting miRs for treating pathological conditions. On the other hand, the application of naturally occurring compounds has been increased due to their minimal side effects and valuable biological and therapeutic activities. Ginsenosides are able to act as anti-tumor agents via either increasing or decreasing the expression level of miRs. Ginsenosides affect the expression profile of miRNAs to induce their protective impacts. Angiogenesis as a key factor in the progression of cancer can be suppressed by ginsenosides which is mediated by miR regulation. The aim of this review is to shed some light on the protective and anti-tumor activities of ginsenosides mediated by miRNAs.

The relevance of microRNA in post-infarction left ventricular remodelling and heart failure

Myocardial infarction and post-infarction left ventricular remodelling involve a high risk of morbidity and mortality. For this reason, ongoing research is being conducted in order to learn the mechanisms of unfavourable left ventricular remodelling following a myocardial infarction. New biomarkers are also being sought that would allow for early identification of patients with a high risk of post-infarction remodelling and dysfunction of the left ventricle. In recent years, there has been ever more experimental data that confirms the significance of microRNA in cardiovascular diseases. It has been confirmed that microRNAs are stable in systemic circulation, and can be directly measured in patients' blood. It has been found that significant changes occur in the concentrations of various types of microRNA in myocardial infarction and heart failure patients. Various types of microRNA are also currently being intensively researched in terms of their usefulness as markers of cardiomyocyte necrosis, and predictors of the post-infarction heart failure development. This paper is a summary of the current knowledge on the significance of microRNA in post-infarction left ventricular remodelling and heart failure.

Short fish-origin DNA elements served as flanking sequences in a knockdown cloning vector enabling the generation of a functional siRNA molecule in mammalian cells and fish embryos

Improving the quality of a siRNA-knockdown cloning vector requires simpler, shorter, and more effective flanking sequences. In this study, we designed such flanking sequences based on those found in zebrafish pre-miR3906, namely, internal element (IE) 1 and IE2. We engineered a vegf-shRNA fragment flanked by an 80-bp IE1/IE2 and then inserted into the 3' UTR of GFP reporter cDNA driven by a cytomegalovirus promoter to obtain a plasmid containing gfp-IE-vegf-shRNA-polA. Upon microinjection of this plasmid into zebrafish embryos, we found that IE flanking sequences could effectively induce the production of vegf-shRNA fragment, which was then processed into a functional siRNA to silence the target vegf121 gene. Northern blot showed that the vegf-shRNA fragment was cleaved from gfp-IE-vegf-shRNA-polA, resulting in the loss of polyA tails, subsequently degrading the remaining RNA-containing GFP. Moreover, Western blot revealed that addition of IE-based vegf-shRNA fragment could markedly decrease the expression of VEGF. Finally, to facilitate a more versatile application of the IE-based knockdown vector, we generated an inducible expression vector in which IE-vegf-shRNA was constructed downstream in a Tet-on system to generate a Tet-on-IE-vegf-shRNA construct. After doxycycline induction, the protein level of VEGF in SW620 cells harboring the Tet-on-IE-vegf-shRNA construct was decreased 77%. Interestingly, when SW620 cells harboring Tet-on-IE-vegf-shRNA cells were induced and transplanted into zebrafish embryos, we found that abnormal branch of the sub-intestinal vessels was reduced in the recipient embryos, suggesting that vegf-shRNA cleaved from Tet-on-IE-vegf-shRNA-polA was processed into a functional vegf-siRNA in embryos suppressing endogenous VEGF and reducing tumor angiogenesis. Therefore, we conclude that fish-origin IEs are flanking sequences with short, simple, and effective DNA elements. This IE-based knockdown cloning vector provides a new alternative material to facilitate the generation of functional siRNA with which to perform loss-of-function experiments, both in vitro (mammalian cells) and in vivo (zebrafish embryos).

RNA activation technique and its applications in cancer research

RNA activation (RNAa) is a mechanism of gene activation mediated by small activating RNAs. The activation of gene expression by small activating RNA has excellent targeting specificity and flexibility, with a persistent and strong effect. Studies have shown that the RNAa technique has broad prospects for application in the research on tumor pathogenesis and the treatment of tumors. This paper reviews the literature on RNAa with regard to the course of discovery, the mechanisms and characteristics of action, and the current status and prospects of application.

miRNA Editing: New Insights into the Fast Control of Gene Expression in Health and Disease

Post-transcriptional modifications are essential mechanisms for mRNA biogenesis and function in eukaryotic cells. Beyond well-characterized events such as splicing, capping, and polyadenylation, there are several others, as RNA editing mechanisms and regulation of transcription mediated by miRNAs that are taking increasing attention in the last years. RNA editing through A-to-I deamination increases transcriptomic complexity, generating different proteins with amino acid substitution from the same transcript. On the other hand, miRNAs can regulate gene expression modulating target mRNA decay and translation. Interestingly, recent studies highlight the possibility that miRNAs might undergo editing themselves. This mainly translates in the degradation or uncorrected maturation of miRNAs but also in the recognition of different targets. The presence of edited and unedited forms of the same miRNA may have important biological implications in both health and disease. Here we review ongoing investigations on miRNA RNA editing with the aim to shed light on the growing importance of this mechanism in adding complexity to post-transcriptional regulation of gene expression.

Magnetic Field-Activated Sensing of mRNA in Living Cells

Detection of specific mRNA in living cells has attracted significant attention in the past decade. Probes that can be easily delivered into cells and activated at the desired time can contribute to understanding translation, trafficking and degradation of mRNA. Here we report a new strategy termed magnetic field-activated binary deoxyribozyme (MaBiDZ) sensor that enables both efficient delivery and temporal control of mRNA sensing by magnetic field. MaBiDZ uses two species of magnetic beads conjugated with different components of a multicomponent deoxyribozyme (DZ) sensor. The DZ sensor is activated only in the presence of a specific target mRNA and when a magnetic field is applied. Here we demonstrate that MaBiDZ sensor can be internalized in live MCF-7 breast cancer cells and activated by a magnetic field to fluorescently report the presence of specific mRNA, which are cancer biomarkers.

Combination of AAV-TRAIL with miR-221-Zip Therapeutic Strategy Overcomes the Resistance to TRAIL Induced Apoptosis in Liver Cancer

TNF-related apoptosis-inducing ligand (TRAIL) possesses the capacity to induce apoptosis in a wide variety of tumor cells without affecting most normal cells. However, it has now emerged that many primary cancer cells are resistant to TRAIL monotherapy. Overcoming the intrinsic or acquired TRAIL resistance is desirable for TRAIL-mediated cancer therapy. In this study, we found that the miR-221/222 cluster was up-regulated in TRAIL-resistant liver cancer cells. Specific inhibitors of miR-221 and/or miR-222, called sponge, TuD and miR-Zip were constructed, and their ability to overcome TRAIL resistance was compared. Among them, AAV-mediated gene therapy using co-expression of TRAIL with miR-221-Zip showed the most synergistic activity in the induction of apoptosis in vitro. In vivo treatment of nude mice bearing human TRAIL-resistant liver cancer xenografts with AAV-TRAIL-miR-221-Zip also led to growth inhibition. This sensitizing effect of miR-221-Zip was associated with increased expression of PTEN, the miR-221 target, as well as with decreasing levels of Survivin. Moreover, miR-221 expression was concomitant with promotion of Survivin expression and suppression of PTEN expression. TRAIL sensitivity of cancer cells isolated from liver cancer tissues or from patients was significantly correlated with miR-221 expression. And miR-221 blood expression levels in liver cancer patients were correlated with TRAIL sensitivity, thus it had the potential to be a predictor of TRAIL sensitivity in liver cancer. These data suggested the potential of combining AAV-TRAIL with miR-221-Zip as a therapeutic intervention for liver cancer.

TGF-beta/atRA-induced Tregs express a selected set of microRNAs involved in the repression of transcripts related to Th17 differentiation

Regulatory T cells (Tregs) are essential regulators of immune tolerance. atRA and TGF-β can inhibit the polarization of naïve T cells into inflammatory Th17 cells, favoring the generation of stable iTregs, however the regulatory mechanisms involved are not fully understood. In this context, the roles of individual microRNAs in Tregs are largely unexplored. Naïve T cells were immunomagnetically isolated from umbilical cord blood and activated with anti-human CD2/CD3/CD28 beads in the presence of IL-2 alone (CD4_Med) or with the addition of TGF-β and atRA (CD4_TGF/atRA). As compared to CD4_Med, the CD4_TGF/atRA condition allowed the generation of highly suppressive CD4⁺CD25^hiCD127⁻FOXP3^hi iTregs. Microarray profiling allowed the identification of a set of microRNAs that are exclusively expressed upon TGF-β/atRA treatment and that are predicted to target a set of transcripts concordantly downregulated. This set of predicted targets were enriched for central components of IL-6/JAK/STAT and AKT-mTOR signaling, whose inhibition is known to play important roles in the generation and function of regulatory lymphocytes. Finally, we show that mimics of exclusively expressed miRs (namely miR-1299 and miR-30a-5p) can reduce the levels of its target transcripts, IL6R and IL6ST (GP130), and increase the percentage of FoxP3⁺ cells among CD4⁺CD25^+/hi cells.

Design and Experimental Validation of Small Activating RNAs Targeting an Exogenous Promoter in Human Cells

It is increasingly practical to co-opt many native cellular components into use as elements of synthetic biological systems. We present the design and experimental investigation of the first exogenous genetic construct to be successfully targeted by RNA activation, a phenomenon whereby small double-stranded RNAs increase gene expression from sequence-similar promoters by a mechanism thought to be related to that of RNA interference. Our selection of activating RNA candidates was informed by a custom-written computer program designed to choose target sites in the promoter of interest according to a set of empirical optimality criteria drawn from prior research. Activating RNA candidates were assessed for activity against two exogenously derived target promoters, with successful candidates being subjected to further rounds of validation as a precaution against potential off-target effects. A genetic platform was assembled that allowed activating RNA candidates to be simultaneously screened both for positive activity on the target reporter gene and for possible nonspecific effects on cell metabolism. Several candidate sequences were tested to appraise the utility of this platform, with the most successful achieving a moderate activation level with minimal off-target effects.

Silencing gut genes associated with the peritrophic matrix of Reticulitermes flavipes (Blattodea: Rhinotermitidae) increases susceptibility to termiticides

The peritrophic matrix (PM) is a noncellular structure that lines the gut of most insects. Because of its close involvement in digestive processes and its role as a barrier against pathogens and toxins, the PM is an attractive target for pest management strategies. The objectives of this study were to (1) reduce the expression of a chitin synthase gene (Reticulitermes flavipes chitin synthase B, RfCHSB), a putative peritrophin [R. flavipes Protein with Peritrophin-A domain 1, (RfPPAD1)] and a confirmed peritrophin [R. flavipes Protein with Peritrophin-A domain 2 (RfPPAD2)] in R. flavipes by means of RNA interference, and (2) to evaluate the susceptibility of R. flavipes to termiticides and a bacterial pathogen, after silencing the target genes. Force feeding termites with 55 and 100 ng of long double-stranded RNAs (dsRNAs), targeting RfCHSB and RfPPAD2, respectively, resulted in the highest levels of transcript suppression. RfCHSB expression was reduced by 70%, whereas the transcript level of RfPPAD2 was decreased by 90%. Force feeding 100 ng/termite of a long RfPPAD1 dsRNA reduced the expression of the transcript by 30%. Challenging termites with imidacloprid, chlorantraniliprole and noviflumuron, after silencing RfCHSB, significantly increased termite mortality. Force feeding termites a dsRNA cocktail, targeting RfCHSB, RfPPAD1 and RfPPAD2, caused the highest significant increase in termite mortality after challenging the insects with imidacloprid. These results demonstrate the viability of the R. flavipes PM as a target in termite pest management.

MicroRNAs activate gene transcription epigenetically as an enhancer trigger

MicroRNAs (miRNAs) are small non-coding RNAs that function as negative gene expression regulators. Emerging evidence shows that, except for function in the cytoplasm, miRNAs are also present in the nucleus. However, the functional significance of nuclear miRNAs remains largely undetermined. By screening miRNA database, we have identified a subset of miRNA that functions as enhancer regulators. Here, we found a set of miRNAs show gene-activation function. We focused on miR-24-1 and found that this miRNA unconventionally activates gene transcription by targeting enhancers. Consistently, the activation was completely abolished when the enhancer sequence was deleted by TALEN. Furthermore, we found that miR-24-1 activates enhancer RNA (eRNA) expression, alters histone modification, and increases the enrichment of p300 and RNA Pol II at the enhancer locus. Our results demonstrate a novel mechanism of miRNA as an enhancer trigger.

Activating frataxin expression by repeat-targeted nucleic acids

Friedreich's ataxia is an incurable genetic disorder caused by a mutant expansion of the trinucleotide GAA within an intronic FXN RNA. This expansion leads to reduced expression of frataxin (FXN) protein and evidence suggests that transcriptional repression is caused by an R-loop that forms between the expanded repeat RNA and complementary genomic DNA. Synthetic agents that increase levels of FXN protein might alleviate the disease. We demonstrate that introducing anti-GAA duplex RNAs or single-stranded locked nucleic acids into patient-derived cells increases FXN protein expression to levels similar to analogous wild-type cells. Our data are significant because synthetic nucleic acids that target GAA repeats can be lead compounds for restoring curative FXN levels. More broadly, our results demonstrate that interfering with R-loop formation can trigger gene activation and reveal a new strategy for upregulating gene expression.

Piwi-interacting RNAs in cancer: emerging functions and clinical utility

PIWI-interacting RNAs (piRNAs) are emerging players in cancer genomics. Originally described in the germline, there are over 20,000 piRNA genes in the human genome. In contrast to microRNAs, piRNAs interact with PIWI proteins, another member of the Argonaute family, and function primarily in the nucleus. There, they are involved in the epigenetic silencing of transposable elements in addition to the transcriptional regulation of genes. It has recently been demonstrated that piRNAs are also expressed across a variety of human somatic tissue types in a tissue-specific manner. An increasing number of studies have shown that aberrant piRNA expression is a signature feature across multiple tumour types; however, their specific tumorigenic functions remain unclear. In this article, we discuss the emerging functional roles of piRNAs in a variety of cancers, and highlight their potential clinical utilities.

Advances in CRISPR-Cas9 genome engineering: lessons learned from RNA interference

The discovery that the machinery of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 bacterial immune system can be re-purposed to easily create deletions, insertions and replacements in the mammalian genome has revolutionized the field of genome engineering and re-invigorated the field of gene therapy. Many parallels have been drawn between the newly discovered CRISPR-Cas9 system and the RNA interference (RNAi) pathway in terms of their utility for understanding and interrogating gene function in mammalian cells. Given this similarity, the CRISPR-Cas9 field stands to benefit immensely from lessons learned during the development of RNAi technology. We examine how the history of RNAi can inform today's challenges in CRISPR-Cas9 genome engineering such as efficiency, specificity, high-throughput screening and delivery for in vivo and therapeutic applications.