Using synthetic miRNA mimics for diverting cell fate: a possibility of miRNA-based therapeutics?
Explore the source record for details and available documents.
Apoptosis↗
SEARCH · PubMed Health
Results for “MicroRNA”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
AtXRN4 degrades mRNA in Arabidopsis and its substrates include selected miRNA targets.
Messenger RNA degradation is an essential step in gene expression that can be regulated by siRNAs or miRNAs. However, most of our knowledge of in vivo eukaryotic mRNA degradation mechanisms derives from Saccharomyces cerevisiae, which lacks miRNAs and RNAi capability. Using reverse genetic and microarray analyses, we have identified multiple substrates of AtXRN4, the Arabidopsis homolog of the major yeast mRNA degrading exoribonuclease, Xrn1p. Insertional mutation of AtXRN4 leads to accumulation of the 3' end of several mRNAs, in a manner that correlates with increased stability of the 3' end, and is reversed following complementation with AtXRN4. Moreover, 3' products of miRNA-mediated cleavage of SCARECROW-LIKE transcripts and several other miRNA target transcripts are among those that accumulate in xrn4 mutants. The demonstration that an Xrn1p homolog degrades mRNA in a multicellular eukaryote and contributes to the miRNA-mediated decay pathway of selected targets has implications for XRNs in other organisms.
Arabidopsis↗
Human Argonaute2 mediates RNA cleavage targeted by miRNAs and siRNAs.
Argonaute proteins associate with small RNAs that guide mRNA degradation, translational repression, or a combination of both. The human Argonaute family has eight members, four of which (Ago1 through Ago4) are closely related and coexpressed in many cell types. To understand the biological function of the different Ago proteins, we set out to determine if Ago1 through Ago4 are associated with miRNAs as well as RISC activity in human cell lines. Our results suggest that miRNAs are incorporated indiscriminately of their sequence into Ago1 through Ago4 containing microRNPs (miRNPs). Purification of the FLAG/HA-epitope-tagged Ago containing complexes from different human cell lines revealed that endonuclease activity is exclusively associated with Ago2. Exogenously introduced siRNAs also associate with Ago2 for guiding target RNA cleavage. The specific role of Ago2 in guiding target RNA cleavage was confirmed independently by siRNA-based depletion of individual Ago members in combination with a sensitive positive-readout reporter assay.
Argonaute Proteins↗
mRNA turnover meets RNA interference.
By using two very different approaches, recent work by Gazzani et al. (2004) and Souret et al. (2004) reveal a fundamental link between mRNA degradation and RNA silencing pathways in Arabidopsis.
Arabidopsis↗
Herpes simplex virus type-1 latency inhibits dendritic growth in sympathetic neurons.
Herpes simplex virus type-1 (HSV-1) initially infects mucoepithelial tissues of the orofacial region, the eye and to a lesser extent the genitalia. Subsequently, the virus is retrogradely transported through the axons of the sensory and sympathetic neurons to their nuclei, where the virus establishes a life-long latent infection. During this latency period, the viral genome is transcriptionally silent except for a single region encoding the latency-associated transcript (LAT). LAT has been shown to affect apoptosis, but little else is known regarding its effects on neurons. To understand how HSV-1 latency might affect dendrites in sympathetic neurons, we transfected primary cultures of sympathetic neurons obtained from rat embryos, with LAT expressing plasmids. LAT inhibited initial dendritic growth and induced dendritic retraction in sympathetic neurons. Latent HSV-1 infection of cultured sympathetic neurons inhibited dendritic growth indicating that this is likely also a consequence of natural infection.
Animals↗
Two alphaherpesvirus latency-associated gene products influence calcitonin gene-related peptide levels in rat trigeminal neurons.
Herpes simplex virus type-1 (HSV-1) initially infects mucoepithelial tissues of the eye and the orofacial region. Subsequently, the virus is retrogradely transported through the axons of the trigeminal sensory neurons. HSV-1 establishes a life-long latent infection in these neurons, during which the transcription of the viral genome is silent, except for the sequences encoding the latency-associated transcript (LAT). To determine if HSV-1 latency might affect calcitonin gene-related peptide (CGRP) expression in trigeminal sensory neurons, we transfected primary neuronal cultures of trigeminal ganglia from rat embryos with plasmids expressing LAT. In the presence of Bone Morphogenetic Protein-7 (BMP7), CGRP was expressed in 49% of sensory neurons. However, this percentage was reduced to 19% in neurons transfected with LAT expressing plasmids. We also found that transfection of the IE63 gene of varicella-zoster virus (VZV) reduced the percentage of trigeminal neurons containing CGRP. However, the observed effect of IE63 in contrast to that of LAT was completely reversed by treatment of cultures with MgCl2, which indicates that the effect of IE63 was due to increased release of CGRP from trigeminal neurons. We provide here the first evidence that HSV-1 LAT decreases the level of CGRP in trigeminal neurons. These effects may be important for reducing the neuroinflammatory response, thus protecting host neuronal cells during HSV-1 latency in trigeminal neurons. In contrast, increased release of CGRP in the presence of IE63 protein may contribute to the neuralgias associated with VZV infection.
Animals↗
Staufen- and FMRP-containing neuronal RNPs are structurally and functionally related to somatic P bodies.
Local control of mRNA translation modulates neuronal development, synaptic plasticity, and memory formation. A poorly understood aspect of this control is the role and composition of ribonucleoprotein (RNP) particles that mediate transport and translation of neuronal RNAs. Here, we show that staufen- and FMRP-containing RNPs in Drosophila neurons contain proteins also present in somatic "P bodies," including the RNA-degradative enzymes Dcp1p and Xrn1p/Pacman and crucial components of miRNA (argonaute), NMD (Upf1p), and general translational repression (Dhh1p/Me31B) pathways. Drosophila Me31B is shown to participate (1) with an FMRP-associated, P body protein (Scd6p/trailer hitch) in FMRP-driven, argonaute-dependent translational repression in developing eye imaginal discs; (2) in dendritic elaboration of larval sensory neurons; and (3) in bantam miRNA-mediated translational repression in wing imaginal discs. These results argue for a conserved mechanism of translational control critical to neuronal function and open up new experimental avenues for understanding the regulation of mRNA function within neurons.
Animals↗
PCBP2 facilitates miR-93-5p-mediated repression of GDF11 in HCC cell lines.
Growth differentiation factor 11 (GDF11), a member of the transforming growth factor-β superfamily, functions in skeletal muscle and neuronal regeneration and has been implicated in tumor suppression. In hepatocellular carcinoma (HCC), GDF11 expression is markedly downregulated, but the mechanisms responsible for this repression remain unclear. In this study, we examined whether the oncogenic miR-106b-25 cluster contributes to GDF11 suppression in HCC. We found that this cluster decreases GDF11 expression at both the mRNA and protein levels, with miR-93-5p acting as the dominant regulator. Inhibition of miR-93-5p with antisense oligonucleotides restored GDF11 expression and reduced HCC cell proliferation, migration, and invasion. Mechanistically, we identified the RNA-binding protein (RBP) PCBP2 as a key facilitator of miR-93-5p targeting of GDF11. PCBP2 binds a C-rich element adjacent to the miR-93-5p target site in the GDF11 3' UTR, thereby enhancing miR-93-5p-mediated repression. PCBP2 knockout attenuated miR-93-5p-mediated repression, whereas re-expression of PCBP2 restored it, supporting its modulatory role. Collectively, these findings identify PCBP2 as a modulator of miR-93-5p-mediated GDF11 repression and suggest that this regulatory interaction contributes to HCC cell proliferation, migration, and invasion. This work provides insights into the post-transcriptional control of the tumor suppressor and highlights the therapeutic potential of targeting miRNA-RBP interactions.
GDF11↗
Time to grow up: the temporal role of smallRNAs in plants.
Over the past two years, several Arabidopsis genes that were initially identified as vegetative phase change mutants have been shown to have roles in smallRNA (sRNA) biogenesis. This has led to the identification of a new class of short interfering RNAs (siRNAs) called trans-acting siRNAs (ta-siRNAs).
Gene Expression Regulation, Developmental↗
RNA interference: mechanisms of action and therapeutic consideration.
Explore the source record for details and available documents.
Genetic Therapy↗
RNA silencing and genome regulation.
Closely related RNA silencing phenomena such as posttranscriptional and transcriptional gene silencing (PTGS and TGS), quelling and RNA interference (RNAi) represent different forms of a conserved ancestral process. The biological relevance of these RNA-directed mechanisms of silencing in gene regulation, genome defence and chromosomal structure is rapidly being unravelled. Here, we review the recent developments in the field of RNA silencing in relation to other epigenetic phenomena and discuss the significance of this process and its targets in the regulation of modern eukaryotic genomes.
Animals↗
miR-6388 regulates granulosa cell function in sheep by targeting GDF9 and modulating the TGF-β signaling pathway.
Litter size is an economically important trait in sheep and is closely associated with ovarian follicular development and granulosa cell (GC) function. This study investigated the association between GDF9 polymorphisms and litter size, and examined the post-transcriptional regulation of GDF9 by miR-6388 in ovine GCs. Variants were initially identified by Sanger sequencing in 20 ewes, and subsequently genotyped in 377 three-year-old ewes, including 231 Sonid (SN) sheep and 146 Ujimqin (UM) sheep for association analysis. Candidate miRNAs targeting litter size-associated variants in the GDF9 3'UTR were predicted, and the miR-6388-GDF9 interaction was evaluated using dual-luciferase reporter assays. RT-qPCR, Western blotting, EdU incorporation, and flow cytometry were used to assess endogenous GDF9 expression and GC function. Twelve single-nucleotide polymorphisms were identified, including the putatively novel variant g.42114076C > G. The linkage disequilibrium block comprising g.42116936C > T, g.42113821T > A, and g.42113962G > A polymorphisms of GDF9 was significantly associated with litter size in both SN and UM sheep, whereas the c.477G > A was associated with litter size only in UM sheep. Reporter assays showed that the GDF9 3'UTR region carrying the G allele of g.42113962G > A was more responsive to miR-6388-mediated repression than the region carrying the A allele. miR-6388 overexpression reduced GDF9 mRNA and GDF9 protein levels, inhibited GC proliferation, altered cell-cycle distribution, and promoted apoptosis, whereas miR-6388 knockdown increased GDF9 expression and GC proliferation and reduced apoptosis. These cellular changes were accompanied by altered expression of cell-cycle and apoptosis-related genes and TGF-β signaling-related components.
Animals↗
Regulating mammalian transcription with RNA.
Recent reports have demonstrated that small duplex RNAs mediate recognition of chromosomal DNA and inhibit transcription within mammalian cells. Key unresolved issues include whether RNAs directly bind to DNA, the identification of the mechanism(s) that convert chromosome recognition into gene silencing and whether naturally occurring antigene RNAs (agRNAs) exist.
Animals↗
Using RNAi to improve plant nutritional value: from mechanism to application.
RNA interference (RNAi) is an ancient mechanism of gene suppression, whose machinery and biological functions are only partially understood. Intensive studies have focused on developing RNAi technologies for treating human diseases and for improving plant traits. Yet application of RNAi to improving the nutritional value of plants for human and animal nutrition, and development of the related RNAi technologies are still in their infancy. Here we discuss current knowledge of plant RNAi function, as well as concepts and strategies for the improvement of plant nutritional value through the development of plant RNAi technologies.
Animals↗
The silent treatment: RNAi as a defense against virus infection in mammals.
RNA interference (RNAi) is a mechanism for sequence-specific gene silencing guided by double-stranded RNA. In plants and insects it is well established that RNAi is instrumental in the response to viral infections; whether RNAi has a similar function in mammals is under intense investigation. Recent studies to address this question have identified some unanticipated interactions between the RNAi machinery and mammalian viruses. Furthermore, introduction of virus-specific small interfering RNAs (siRNAs) into cells, thus programming the RNAi machinery to target viruses, is an effective therapeutic approach to inhibit virus replication in vitro and in animal models. Although several issues remain to be addressed, such as delivery and viral escape, these findings hold tremendous potential for the development of RNAi-based antiviral therapeutics.
Animals↗
Micros for microbes: non-coding regulatory RNAs in bacteria.
Small non-coding RNAs with important regulatory roles are not confined to eukaryotes. Recent studies have led to the identification of numerous small regulatory RNAs in Escherichia coli and in other bacteria. As in eukaryotic cells, a major class of these small RNAs acts by base-pairing with target mRNAs, resulting in changes in the translation and stability of the mRNA. Roles for these non-coding pairing RNAs in bacteria have been demonstrated in several cases. Because these non-coding RNAs act post-transcriptionally, they impose a regulatory step that is independent of and epistatic to any transcriptional signals for their target mRNAs.
Bacterial Proteins↗
Rapid evolution of noncoding RNAs: lack of conservation does not mean lack of function.
The mammalian transcriptome contains many non-protein-coding RNAs (ncRNAs), but most of these are of unclear significance and lack strong sequence conservation, prompting suggestions that they might be non-functional. However, certain long functional ncRNAs such as Air and Xist are also poorly conserved. In this article, we systematically analyzed the conservation of several groups of functional ncRNAs, including miRNAs, snoRNAs and longer ncRNAs whose function has been either documented or confidently predicted. As expected, miRNAs and snoRNAs were highly conserved. By contrast, the longer functional non-micro, non-sno ncRNAs were much less conserved with many displaying rapid sequence evolution. Our findings suggest that longer ncRNAs are under the influence of different evolutionary constraints and that the lack of conservation displayed by the thousands of candidate ncRNAs does not necessarily signify an absence of function.
Animals↗