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Transgene-like animal models using intronic microRNAs.

Transgenic animal models are valuable tools for testing gene functions and drug mechanisms in vivo. They are also the best similitude of a human body for etiological and pathological research of diseases. All pharmaceutically developed drugs must be proven safe and effective in animals before approval by the Food and Drug Administration to be used in clinical trials. To this end, the transgenic animal models of human diseases serve as a front line for drug evaluation. However, there is currently no transgenic animal model for microRNA (miRNA) research. miRNAs, small single-stranded regulatory RNAs capable of silencing intracellular gene transcripts that contain either complete or partial complementarity to the miRNAs, are useful for the design and development of new therapies against cancer polymorphism and viral mutation. Recently, varieties of natural miRNAs have been found to be derived from hairpin-like RNA precursors in almost all eukaryotes, including yeast (Schizosaccharomyces pombe), plant (Arabidopsis), nematode (Caenorhabditis elegans), fly (Drosophila melanogaster), fish, mouse, and human, involving intracellular defense against viral infections and regulation of certain gene expressions during development. To facilitate the miRNA research in vivo, we have developed a state-of-the-art transgenic strategy for silencing specific genes in zebrafish, chicken, and mouse, using intronic miRNAs. By insertion of a hairpin-like pre-miRNA structure into the intron region of a gene, we have found that mature miRNAs were successfully transcribed by RNA polymerase (Pol)-II, coexpressed with the encoding gene transcript, and excised out of the encoding gene transcript by natural RNA splicing and processing mechanisms. In conjunction with retroviral transfection systems, the hairpin-like pre-miRNA construct was further inserted into the intron of a cellular gene for tissue-specific expression regulated by the gene promoter. Because the retroviral vectors were randomly integrated into the genome of its host cell, the most effective transgenic animal can be selected and propagated to be a stable transgenic line for future research. Here, we have shown for the first time that transgene-like animal models were generated using the intronic miRNA-expressing system described previously, which has been proven to be useful for both miRNA research and in vivo evaluation of miRNA-associated target genes.

Animals↗

Computational identification of plant microRNAs and their targets, including a stress-induced miRNA.

MicroRNAs (miRNAs) are approximately 21-nucleotide RNAs, some of which have been shown to play important gene-regulatory roles during plant development. We developed comparative genomic approaches to systematically identify both miRNAs and their targets that are conserved in Arabidopsis thaliana and rice (Oryza sativa). Twenty-three miRNA candidates, representing seven newly identified gene families, were experimentally validated in Arabidopsis, bringing the total number of reported miRNA genes to 92, representing 22 families. Nineteen newly identified target candidates were confirmed by detecting mRNA fragments diagnostic of miRNA-directed cleavage in plants. Overall, plant miRNAs have a strong propensity to target genes controlling development, particularly those of transcription factors and F-box proteins. However, plant miRNAs have conserved regulatory functions extending beyond development, in that they also target superoxide dismutases, laccases, and ATP sulfurylases. The expression of miR395, the sulfurylase-targeting miRNA, increases upon sulfate starvation, showing that miRNAs can be induced by environmental stress.

Arabidopsis↗

Genome-wide analysis of mRNAs regulated by Drosha and Argonaute proteins in Drosophila melanogaster.

RNA silencing pathways are conserved gene regulation mechanisms that elicit decay and/or translational repression of mRNAs complementary to short interfering RNAs and microRNAs (miRNAs). The fraction of the transcriptome regulated by these pathways is not known, but it is thought that each miRNA may have hundreds of targets. To identify transcripts regulated by silencing pathways at the genomic level, we examined mRNA expression profiles in Drosophila melanogaster cells depleted of four Argonaute paralogs (i.e., AGO1, AGO2, PIWI, or Aubergine) that play essential roles in RNA silencing. We also profiled cells depleted of the miRNA-processing enzyme Drosha. The results reveal that transcripts differentially expressed in Drosha-depleted cells have highly correlated expression in the AGO1 knockdown and are significantly enriched in predicted and validated miRNA targets. The levels of a subset of miRNA targets are also regulated by AGO2. Moreover, AGO1 and AGO2 silence the expression of a common set of mobile genetic elements. Together, these results indicate that the functional overlap between AGO1 and AGO2 in Drosophila is more important than previously thought.

Animals↗

Comparative genomics modeling of the NRSF/REST repressor network: from single conserved sites to genome-wide repertoire.

We constructed and applied an open source informatic framework called Cistematic in an effort to predict the target gene repertoire for transcription factors with large binding sites. Cistematic uses two different evolutionary conservation-filtering algorithms in conjunction with several analysis modules. Beginning with a single conserved and biologically tested site for the neuronal repressor NRSF/REST, Cistematic generated a refined PSFM (position specific frequency matrix) based on conserved site occurrences in mouse, human, and dog genomes. Predictions from this model were validated by chromatin immunoprecipitation (ChIP) followed by quantitative PCR. The combination of transfection assays and ChIP enrichment data provided an objective basis for setting a threshold for membership and rank-ordering a final gene cohort model consisting of 842 high-confidence sites in the human genome associated with 733 genes. Statistically significant enrichment of NRSE-associated genes was found for neuron-specific Gene Ontology (GO) terms and neuronal mRNA expression profiles. A more extensive evolutionary survey showed that NRSE sites matching the PSFM model exist in roughly similar numbers in all fully sequenced vertebrate genomes but are notably absent from invertebrate and protochordate genomes, as is NRSF itself. Some NRSF/REST sites reside in repeats, which suggests a mechanism for both ancient and modern dispersal of NRSEs through vertebrate genomes. Multiple predicted sites are located near neuronal microRNA and splicing-factor genes, and these tested positive for NRSF/REST occupancy in vivo. The resulting network model integrates post-transcriptional and translational controllers, including candidate feedback loops on NRSF and its corepressor, CoREST.

Animals↗

Phylogenetic shadowing and computational identification of human microRNA genes.

We sequenced 122 miRNAs in 10 primate species to reveal conservation characteristics of miRNA genes. Strong conservation is observed in stems of miRNA hairpins and increased variation in loop sequences. Interestingly, a striking drop in conservation was found for sequences immediately flanking the miRNA hairpins. This characteristic profile was employed to predict novel miRNAs using cross-species comparisons. Nine hundred and seventy-six candidate miRNAs were identified by scanning whole-genome human/mouse and human/rat alignments. Most of the novel candidates are conserved also in other vertebrates (dog, cow, chicken, opossum, zebrafish). Northern blot analysis confirmed the expression of mature miRNAs for 16 out of 69 representative candidates. Additional support for the expression of 179 novel candidates can be found in public databases, their presence in gene clusters, and literature that appeared after these predictions were made. Taken together, these results suggest the presence of significantly higher numbers of miRNAs in the human genome than previously estimated.

Computational Biology↗

Premeiotic 24-nt phasiRNAs are present in the Zea genus and unique in biogenesis mechanism and molecular function.

Reproductive phasiRNAs are broadly present in angiosperms and play crucial roles in sustaining male fertility. While the premeiotic 21-nt phasiRNAs and meiotic 24-nt phasiRNA pathways have been extensively studied in maize (Zea mays) and rice (Oryza sativa), a third putative category of reproductive phasiRNAs-named premeiotic 24-nt phasiRNAs-have recently been reported in barley (Hordeum vulgare) and wheat (Triticum aestivum). To determine whether premeiotic 24-nt phasiRNAs are also present in maize and related species and begin to characterize their biogenesis and function, we performed a comparative transcriptome and degradome analysis of premeiotic and meiotic anthers from five maize inbred lines and three teosinte species/subspecies. Our data indicate that a substantial subset of the 24-nt phasiRNA loci in maize and teosinte are already highly expressed at premeiotic phase. The premeiotic 24-nt phasiRNAs are similar to meiotic 24-nt phasiRNAs in genomic origin and dependence on DCL5 for biogenesis, however, premeiotic 24-nt phasiRNAs are unique in that they are likely (i) not triggered by microRNAs, (ii) not loaded by AGO18 proteins, and (iii) not capable of mediating cis-cleavage. In addition, we also observed a group of premeiotic 24-nt phasiRNAs in rice using previously published data. Together, our results indicate that the premeiotic 24-nt phasiRNAs constitute a unique class of reproductive phasiRNAs and are present more broadly in the grass family (Poaceae) than previously known.

Maize↗

MicroRNA-binding viral protein interferes with Arabidopsis development.

MicroRNAs (miRNAs) are small (approximately 21 nt), noncoding RNAs that negatively regulate target mRNAs at the posttranscriptional level that are involved in development. In plants, virus-induced disease symptoms often result in developmental abnormalities resembling perturbation of miRNA-mediated function. Here, we report that expression in transgenic plants of a geminivirus-encoded AC4 protein from African cassava mosaic virus Cameroon Strain (ACMV), a suppressor of posttranscriptional gene silencing, was correlated with decreased accumulation of host miRNAs and increased development abnormalities in Arabidopsis. Down-regulation of miRNA correlated with an up-regulation of target mRNA level. In vitro binding assays revealed the ability of AC4 of ACMV (A-AC4) but not East African cassava mosaic Cameroon virus AC2 to bind single-stranded forms of miRNAs and short interfering RNAs but not double-stranded RNA forms. Normally, a labile intermediate during the miRNA biogenesis/RNA-induced silencing complex assembly, miRNA*, was below the level of detection, indicating that AC4 might interfere at a point downstream of the miRNA duplex unwinding process. The association of AC4 with miRNA was demonstrated by the association of A-AC4-GFP fusion protein, extracted from Arabidopsis protoplasts, with 2'-O-methyloligonucleotide complementary to miR159 (miR159*) and by the presence of miRNA with the A-AC4-GFP fusion protein after immunoprecipitation with antibody against GFP. In both assays, A-AC4 protein and miRNA complexes were copurified. These results provide direct evidence that AC4 is a unique virus-encoded posttranscriptional gene-silencing suppressor protein that binds to and presumably inactivates mature miRNAs and thus blocks the normal miRNA-mediated regulation of target mRNAs, resulting in developmental defects in Arabidopsis.

Arabidopsis↗

MicroRNA-directed cleavage of HOXB8 mRNA.

MicroRNAs (miRNAs) are endogenous approximately 22-nucleotide RNAs, some of which are known to play important regulatory roles in animals by targeting the messages of protein-coding genes for translational repression. We find that miR-196, a miRNA encoded at three paralogous locations in the A, B, and C mammalian HOX clusters, has extensive, evolutionarily conserved complementarity to messages of HOXB8, HOXC8, and HOXD8. RNA fragments diagnostic of miR-196-directed cleavage of HOXB8 were detected in mouse embryos. Cell culture experiments demonstrated down-regulation of HOXB8, HOXC8, HOXD8, and HOXA7 and supported the cleavage mechanism for miR-196-directed repression of HOXB8. These results point to a miRNA-mediated mechanism for the posttranscriptional restriction of HOX gene expression during vertebrate development and demonstrate that metazoan miRNAs can repress expression of their natural targets through mRNA cleavage in addition to inhibiting productive translation.

3' Untranslated Regions↗

Highly specific gene silencing by artificial microRNAs in Arabidopsis.

Plant microRNAs (miRNAs) affect only a small number of targets with high sequence complementarity, while animal miRNAs usually have hundreds of targets with limited complementarity. We used artificial miRNAs (amiRNAs) to determine whether the narrow action spectrum of natural plant miRNAs reflects only intrinsic properties of the plant miRNA machinery or whether it is also due to past selection against natural miRNAs with broader specificity. amiRNAs were designed to target individual genes or groups of endogenous genes. Like natural miRNAs, they had varying numbers of target mismatches. Previously determined parameters of target selection for natural miRNAs could accurately predict direct targets of amiRNAs. The specificity of amiRNAs, as deduced from genome-wide expression profiling, was as high as that of natural plant miRNAs, supporting the notion that extensive base pairing with targets is required for plant miRNA function. amiRNAs make an effective tool for specific gene silencing in plants, especially when several related, but not identical, target genes need to be downregulated. We demonstrate that amiRNAs are also active when expressed under tissue-specific or inducible promoters, with limited nonautonomous effects. The design principles for amiRNAs have been generalized and integrated into a Web-based tool (http://wmd.weigelworld.org).

Arabidopsis↗

Deciphering miRNA-mediated genetic architecture of immune cell subsets in hypertrophic scars and keloids: A 2-step Mendelian randomization study unveiling causal associations.

This study aimed to investigate the potential causal roles of specific circulating microRNAs (miRNAs) and immune cell subsets in the pathogenesis of hypertrophic scars and keloids using a 2-step Mendelian randomization framework. We employed a 2-sample Mendelian randomization approach to evaluate the causal relationships between miRNAs, immune cell genotypes, and scar phenotypes. The analysis integrated miRNA expression quantitative trait loci, immune cell genome-wide association studies, and scar datasets. A 2-step mediation analysis was conducted to assess the indirect effects of miRNAs on scars through immune cell genotypes, using inverse variance weighted methods and complementary sensitivity analyses to ensure robustness. Our analysis identified significant associations between specific miRNAs and scar phenotypes. Notably, miR-6887-5p exhibited a total effect on keloid formation risk (β = 0.324, 95% confidence interval [CI]: 0.073-0.576) and a direct effect (β = 0.283, 95% CI: 0.027, 0.538), with a marginally significant mediation effect through B-cell activating factor receptor on CD20- CD38- B cells (β = 0.042, 95% CI: -0.001, 0.084, P = .047). For hypertrophic scars, miR-345-5p demonstrated a significant total effect (β = -0.501, 95% CI: -0.903, -0.099) and direct effect (β = -0.469, 95% CI: -0.872, -0.066), with a significant mediation effect through CD28+ CD45RA- CD8dim T cell percentage (β = -0.032, 95% CI: -0.062, -0.002, P = .034). miR-4801 showed a significant total effect (β = -0.246, 95% CI: -0.429, -0.064) and direct effect (β = -0.218, 95% CI: -0.402, -0.033), with a marginally significant mediation effect through T cell absolute count (β = -0.028, 95% CI: -0.057, -0.000, P = .043). These findings highlight the interplay between miRNAs and immune cell subsets in scar pathogenesis. This study provides preliminary evidence for the causal roles of specific miRNAs and immune cell subsets in scar formation, emphasizing the potential of miRNA-immune cell axes as therapeutic targets. While the identified associations offer important insights into the molecular mechanisms of scar heterogeneity, further validation through mechanistic studies and clinical trials is necessary to translate these genetic insights into clinical interventions.

Humans↗

Uncovering essential anesthetics-induced exosomal miRNAs related to hepatocellular carcinoma progression: a bioinformatic investigation.

BACKGROUND: Anesthetic drugs may alter exosomal microRNA (miRNA) contents and mediate cancer progression and tumor microenvironment remodeling. Our study aims to explore how the anesthetics (sevoflurane and propofol) impact the miRNA makeup within exosomes in hepatocellular carcinoma (HCC), alongside the interconnected signaling pathways linked to the tumor immune microenvironment. METHODS: In this prospective study, we collected plasma exosomes from two groups of HCC patients (n&#x2009;=&#x2009;5 each) treated with either propofol or sevoflurane, both before anesthesia and after hepatectomy. Exosomal miRNA profiles were assessed using next-generation sequencing (NGS). Furthermore, the expression data from The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) was used to pinpoint the differentially expressed exosomal miRNAs (DEmiRNAs) attributed to the influence of propofol or sevoflurane in the context of HCC. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used to dissect the signaling pathways and biological activities associated with the identified DEmiRNAs and their corresponding target genes. RESULTS: A total of 35 distinct DEmiRNAs were exclusively regulated by either propofol (n&#x2009;=&#x2009;9) or sevoflurane (n&#x2009;=&#x2009;26). Through TCGA-LIHC database analysis, 8 DEmiRNAs were associated with HCC. These included propofol-triggered miR-452-5p and let-7c-5p, as well as sevoflurane-induced miR-24-1-5p, miR-122-5p, miR-200a-3p, miR-4686, miR-214-3p, and miR-511-5p. Analyses revealed that among these 8 DEmiRNAs, the upregulation of miR-24-1-5p consistently demonstrated a significant association with lower histological grades (p&#x2009;<&#x2009;0.0001), early-stage tumors (p&#x2009;<&#x2009;0.05) and higher survival (p&#x2009;=&#x2009;0.029). Further analyses using GSEA and GSVA indicated that miR-24-1-5p, along with its target genes, were involved in governing the tumor immune microenvironment and potentially inhibiting tumor progression in HCC. CONCLUSIONS: This study provided bioinformatics evidence suggesting that sevoflurane-induced plasma exosomal miRNAs may have a potential impact on the immune microenvironment of HCC. These findings established a foundation for future research into mechanistic outcomes in cancer patients.

Carcinoma, Hepatocellular↗

Chromosomal translocations fusing the BCL6 gene to different partner loci are recurrent in primary central nervous system lymphoma and may be associated with aberrant somatic hypermutation or defective class switch recombination.

Primary central nervous system lymphomas (PCNSLs) are diffuse large B cell lymphomas confined to the brain. Only minimal data exist on chromosomal aberrations underlying PCNSLs. We studied 41 PCNSLs by fluorescence in situ hybridization for breakpoints affecting the BCL6 locus in chromosomal band 3q27. Of 37 cases evaluable, 14 (38%) carried a breakpoint in the BCL6 locus. Two of these showed juxtaposition of BCL6 to the IGH locus. In 4 cases, the BCL6 breakpoints were cloned using long-distance inverse polymerase chain reaction. All breakpoints were located within the BCL6 major translocation cluster. The translocation partners were the IGH gene in 14q32.33, the IGL gene in 22q11.22, and the histone 1 H4I gene in 6p22.1. In the fourth case, a deletion in 3q leads to loss of an 837-kb fragment extending from the first intron of BCL6 to the third intron of the lipoma-preferred partner (LPP) gene. This deletion may bring the BCL6 gene under the control of regulatory elements of the LPP gene or the miRNA-28 gene located in intron 4 of LPP. DNA sequence analysis of the junctional sequences provided evidence that aberrant class switch recombination or somatic hypermutation may be involved in the generation of BCL6 translocations.

Base Sequence↗

Tracing the molecular route to progression in miRNA-biogenesis-defective thyroid lesions.

Germline and somatic changes in DICER1 and DGCR8 microprocessors confer risk of developing benign and malignant thyroid lesions, yet the molecular events driving malignant transformation remain unclear. We trace the molecular trajectories from benignity to malignancy in DICER1- and DGCR8-mutated thyroid lesions using multiomic profiling on over 30 DICER1-/DGCR8-mutated samples. Our findings reveal a progressive, specific, and linear accumulation of genetic changes, which when combined with enhanced downregulation of miRNAs distinguished DICER1-/DGCR8-malignant lesions from their benign counterparts. Compensatory hypomethylation of miRNA-encoding genes characterized DICER1-/DGCR8-benign lesions, but as the tumors progressed to malignancy, methylation was partly reimposed, reversing the attempts to activate miRNA-encoded genes and further compromising miRNA production. Transcriptomic analyses revealed mutation-specific effects on the microenvironment, whereby DICER1 mutations activated canonical thyroid cancer progression pathways, whereas altered DGCR8 associated with immune-related changes. This work unveils specific molecular events underlying malignant progression of miRNA-biogenesis-related thyroid tumors and identifies potential biomarkers and disease etiology mechanisms.

MicroRNAs↗

Reliable prediction of Drosha processing sites improves microRNA gene prediction.

MOTIVATION: Mature microRNAs (miRNAs) are processed from long hairpin transcripts. Even though it is only the first of several steps, the initial Drosha processing defines the mature product and is characteristic for all miRNA genes. Methods that can separate between true and false processing sites are therefore essential to miRNA gene discovery. RESULTS: We present a classifier that predicts 5' Drosha processing sites in hairpins that are candidate miRNAs. The classifier, called Microprocessor SVM, correctly predicts the processing site for 50% of known human 5' miRNAs, and 90% of its predictions are within two nucleotides of the true site. Another classifier that is trained on the output from the Microprocessor SVM outperforms existing methods for prediction of unconserved miRNAs. Reanalysis of characteristics and supporting evidence for a set of newly annotated miRNAs shows that some miRNAs may be misannotated. This suggests that expressed hairpins should not be annotated as miRNAs until they are verified to be Drosha and Dicer substrates. AVAILABILITY: The classifiers are publicly available at https://demo1.interagon.com/miRNA/

Artificial Intelligence↗

MicroRNAs and other small RNAs enriched in the Arabidopsis RNA-dependent RNA polymerase-2 mutant.

The Arabidopsis genome contains a highly complex and abundant population of small RNAs, and many of the endogenous siRNAs are dependent on RNA-Dependent RNA Polymerase 2 (RDR2) for their biogenesis. By analyzing an rdr2 loss-of-function mutant using two different parallel sequencing technologies, MPSS and 454, we characterized the complement of miRNAs expressed in Arabidopsis inflorescence to considerable depth. Nearly all known miRNAs were enriched in this mutant and we identified 13 new miRNAs, all of which were relatively low abundance and constitute new families. Trans-acting siRNAs (ta-siRNAs) were even more highly enriched. Computational and gel blot analyses suggested that the minimal number of miRNAs in Arabidopsis is approximately 155. The size profile of small RNAs in rdr2 reflected enrichment of 21-nt miRNAs and other classes of siRNAs like ta-siRNAs, and a significant reduction in 24-nt heterochromatic siRNAs. Other classes of small RNAs were found to be RDR2-independent, particularly those derived from long inverted repeats and a subset of tandem repeats. The small RNA populations in other Arabidopsis small RNA biogenesis mutants were also examined; a dcl2/3/4 triple mutant showed a similar pattern to rdr2, whereas dcl1-7 and rdr6 showed reductions in miRNAs and ta-siRNAs consistent with their activities in the biogenesis of these types of small RNAs. Deep sequencing of mutants provides a genetic approach for the dissection and characterization of diverse small RNA populations and the identification of low abundance miRNAs.

Arabidopsis↗

The investigation of human cerebrospinal fluid exosome in spinal cord injury.

Spinal cord injury (SCI) leads to severe neurological and functional impairments, yet reliable biomarkers for assessing injury severity and predicting recovery remain limited. Cerebrospinal fluid (CSF) is in direct contact with the central nervous system and provides a valuable source for detecting molecular changes after SCI. Although exosomal microRNAs (miRNAs) and proteins are increasingly recognized as mediators of intercellular communication, the role of human CSF exosomes in SCI has not been systematically investigated. To identify exosome-based biomarkers and potential therapeutic targets, we analyzed CSF and serum exosomes from patients with acute SCI using RNA sequencing and proteomic profiling. Weighted gene co-expression network analysis identified 6 gene modules significantly associated with injury severity and neurological recovery at 3 months. Proteomic analysis revealed a 5-protein panel that distinguished complete from incomplete SCI and a 4-protein panel that predicted neurological improvement. Additionally, 15 CSF-specific and 9 serum-specific exosomal miRNAs were identified independent of injury severity. Among 10 tested miRNAs associated with neurological recovery, 7 regulated astrocyte proliferation, and 6 promoted neurite extension and synapse formation. Overall, this study provides a comprehensive characterization of CSF exosomal miRNAs and proteins in human SCI and identifies molecular signatures associated with injury severity and recovery.

Humans↗

Systematic review and meta-analysis of circulating microRNAs in dengue infection: biomarkers, pathogenesis, and clinical implications.

Dengue infection is a mosquito-borne disease that can cause mild illness or severe haemorrhagic fever. Predictive biomarkers for severe cases, especially those with bleeding manifestations or plasma leakage, are currently lacking. This systematic review and meta-analysis synthesises findings from studies on circulating miRNAs in dengue infection, sourced from PubMed, Scopus, Science Direct, and Web of Science, with quality assessed by the Newcastle-Ottawa Scale (PROSPERO: CRD42024521685). Quantitative meta-analyses were conducted using RStudio to evaluate diagnostic Area Under the Curve (AUC) metrics across five eligible studies and Standardised Mean Differences (SMD) for differential miRNA expression. Key miRNAs, such as miR-146a, miR-150, miR-378, miR-21-5p, and miR-1246, were found to regulate immune responses, inflammation, and viral replication. Meta-analysis demonstrated high overall diagnostic accuracy for circulating miRNAs, with individual reported AUC values ranging from 0.79 to 1.00; however, substantial statistical heterogeneity was observed across pooled metrics (I-squared exceeding 89%). SMD analysis highlighted significant upregulation of acute inflammatory drivers, including miR-21-5p (SMD&#x2009;=&#x2009;4.67) and miR-450b-5p (SMD&#x2009;=&#x2009;6.76), alongside marked downregulation of endothelial-protective markers such as miR-126-3p (SMD&#x2009;=&#x2009;-1.31). Rather than viewing dysregulated microRNAs as a uniform class of clinical tools, this review highlights that candidate microRNAs span distinct translational tiers. Recognising these validation levels alongside pre-analytical and biological heterogeneity is essential for prioritising the most viable microRNA candidates for future prospective clinical translation and targeted therapies in dengue management.

Humans↗

RNA interference: traveling in the cell and gaining functions?

Double-stranded RNA can induce the degradation of homologous RNAs in organisms as diverse as protozoa, animals, plants and fungi, resulting in post-transcriptional gene silencing. But in some species, RNA-mediated processes can also lead to translational repression, DNA methylation, heterochromatin formation or DNA elimination. In some situations, amplification of the 'trigger' double-stranded RNA seems to be required for efficient silencing. These findings imply that RNA-mediated mechanisms can control gene expression at both the transcriptional and the post-transcriptional level, and that they can operate in the nuclear and the cytoplasmic compartments.

Animals↗