Project description:Recent studies have indicated important roles for long noncoding RNAs (lncRNAs) as potential essential regulators of myogenesis and adult skeletal muscle regeneration. However, in vivo, the role and mechanism of lncRNAs in myogenic differentiation of adult skeletal muscle stem cells (MuSCs) and myogenesis are still largely unknown. Here, we identified a skeletal muscle specific-enriched lncRNA (myogenesis-associated lncRNA, short for lnc-mg). In vivo, skeletal muscle conditional knockout of lnc-mg resulted in muscle atrophy and the loss of muscular endurance during exercise. Alternatively, skeletal muscle-specific overexpression of lnc-mg promoted muscle hypertrophy in mice. In vitro analyses of primary skeletal muscle cells isolated from mice showed that expression of lnc-mg was increased gradually during myogenic differentiation and overexpressed lnc-mg improved cell differentiation. Mechanistically, lnc-mg promoted myogenesis, by functioning as a competing endogenous RNA (ceRNA) for miR-125b to control protein abundance of Igf2. These findings identify lnc-mg as a novel and important noncoding regulator for muscle cell differentiation and skeletal muscle development. In order to test the hypothesis that lnc-mg may function as a ceRNA leading to the liberation of corresponding miRNA-targeted transcripts, microarrays were performed to detect miRNAs expression in lnc-mg overexpression and lnc-mg knockdown C2C12 cells.
Project description:Recent studies have indicated important roles for long noncoding RNAs (lncRNAs) as potential essential regulators of myogenesis and adult skeletal muscle regeneration. However, in vivo, the role and mechanism of lncRNAs in myogenic differentiation of adult skeletal muscle stem cells (MuSCs) and myogenesis are still largely unknown. Here, we identified a skeletal muscle specific-enriched lncRNA (myogenesis-associated lncRNA, short for lnc-mg). In vivo, skeletal muscle conditional knockout of lnc-mg resulted in muscle atrophy and the loss of muscular endurance during exercise. Alternatively, skeletal muscle-specific overexpression of lnc-mg promoted muscle hypertrophy in mice. In vitro analyses of primary skeletal muscle cells isolated from mice showed that expression of lnc-mg was increased gradually during myogenic differentiation and overexpressed lnc-mg improved cell differentiation. Mechanistically, lnc-mg promoted myogenesis, by functioning as a competing endogenous RNA (ceRNA) for miR-125b to control protein abundance of Igf2. These findings identify lnc-mg as a novel and important noncoding regulator for muscle cell differentiation and skeletal muscle development. In order to identify functional lncRNAs correlating with myogenesis, microarrays were performed to detect the lncRNAs expression profile in undifferentiated MuSCs (GM, growth media/GM) ) and differentiated MuSCs (DM, differentiation media/DM).
Project description:Endogenous retroviruses (ERVs) are transposable elements that cause host genome instability and usually play deleterious roles such as tumorigenesis. Recent advances also suggest that this 'enemy within' may encode viral mimic to induce antiviral immune responses through viral sensors. Here, through whole genome RNA-seq we discovered a full-length ERV-derived long non-coding RNA (lncRNA), designated lnc-EPAV (ERV-derived lncRNA positively regulates antiviral responses), as a positive regulator of NF-κB signaling. Lnc-EPAV expression was rapidly up-regulated by viral RNA mimic or RNA viruses to facilitate the expression of RELA, an NF-κB subunit that plays a critical role in antiviral responses. In turn, RELA promoted the transcription of lnc-EPAV to form a positive feedback loop. Transcriptome analysis of lnc-EPAV-silenced macrophages, combined with gain- and loss-of-function experiments, showed that lnc-EPAV was critical for induction of type I interferon (IFN) and inflammatory cytokine expression by RNA viruses. Consistently, lnc-EPAV-deficient mice exhibited reduced expression of type I IFNs, and consequently increased viral loads and mortality following lethal RNA virus infection. Mechanistically, lnc-EPAV promoted expression of RELA by competitively binding to and displacing SFPQ, a transcriptional repressor of RELA. The binding between ERV-derived RNAs and SFPQ also existed in human cells. Altogether, our work demonstrates an alternative mechanism by which ERVs regulate antiviral immune responses.
Project description:Long non-coding RNAs are important regulators of diverse biological prosesses. Here, we report on functional identification and characterization of a novel long intergenic noncoding RNA with MyoD-regulated and skeletal muscle-restricted expression that promotes the activation of the myogenic program, and is therefore termed Linc-RAM (Linc-RNA Activator of Myogenesis). Linc-RAM is transcribed from an intergenic region of myogenic cells and its expression is upregulated during myogenesis. Notably, in vivo functional studies show that Linc-RAM knockout mice display impaired muscle regeneration due to differentiation defect of satellite cells. Mechanistically, Linc-RAM regulates expression of myogenic genes by directly binding MyoD, which in turn promotes the assembly of the MyoD-Baf60c-Brg1 complex on the regulatory elements of target genes. Collectively, our findings reveal the functional role and molecular mechanism of a lineage-specific Linc-RAM as a regulatory lncRNA required for tissues-specific chromatin remodeling and gene expression.
Project description:MicroRNA (miRNA) play a major role in the post-transcriptional regulation of gene expression. In mammals most miRNA derive from the introns of protein coding genes where they exist as hairpin structures in the primary gene transcript, synthesized by RNA polymerase II (Pol II). These are cleaved co-transcriptionally by the Microprocessor complex, comprising DGCR8 and the RNase III endonuclease Drosha, to release the precursor (pre-)miRNA hairpin, so generating both miRNA and spliced messenger RNA1-4. However, a substantial minority of miRNA originate from Pol II-synthesized long non coding (lnc) RNA where transcript processing is largely uncharacterized5. Here, we show that most lnc-pri-miRNA do not use the canonical cleavage and polyadenylation (CPA) transcription termination pathway6, but instead use Microprocessor cleavage both to release pre-miRNA and terminate transcription. We present a detailed characterization of one such lnc-pri-miRNA that generates the highly expressed liver-specific miR-1227. Genome-wide analysis then reveals that Microprocessor-mediated transcription termination is commonly used by lnc-pri-miRNA but not by protein coding miRNA genes. This identifies a fundamental difference between lncRNA and pre-mRNA processing. Remarkably, inactivation of the Microprocessor can lead to extensive transcriptional readthrough of lnc-pri-miRNA, resulting in inhibition of downstream genes by transcriptional interference. Consequently we define a novel RNase III-mediated, polyadenylation-independent mechanism of Pol II transcription termination in mammalian cells. Chromatin associated RNA-seq from sicntrl,siDrosha,siDGCR8 treated Hela cells. Same for sicntrl and siDGCR8 from Huh7 cells. Nuclear polyA + and polyA- RNA-seq from sicntrl and siDGCR8 in HeLa cells. Chromatin associated RNA-seq from siDicer treated Hela cells.
Project description:Guanine-quadruplexes (G4) present in RNA and DNA exert a number of different functions in the nucleus and in the cytoplasm. However, the molecular mechanisms of G4-mediated regulation are still poorly understood. We describe a regulatory circuitry operating in the early phases of muscle differentiation in which a long non coding RNA (SMaRT) base pairs with a G4-containing mRNA (Mlx-g) and represses its translation in an antagonistic way with the RNA helicase DHX36. MLX-g is required to allow the nuclear translocation of the MLX-a and b dimerization partners and to control proper myogenesis. We show that by controlling MLX-g, lnc-SMaRT is able to regulate the overall quantity of nuclear MLX proteins and their transcriptional output. Therefore, the circuitry composed by lnc-SMaRT, Mlx-g and Dhx36 not only plays an important role in the control of myogenesis but unravels a molecular mechanism where G4 structures and G4 unwinding activities are controlled in vivo.
Project description:The evolution of brain complexity correlates with an increased expression of long, non-coding (lnc) RNAs in neuronal tissues. Although prominent examples illustrate the potential of lncRNAs to scaffold and target epigenetic regulators to chromatin loci, only few cases have been described to function during neurogenesis. We present a first functional characterization of the lncRNA LINC01322, which we term RUS for ‘RNA upstream of Slitrk3’. The RUS gene is well conserved in mammals by sequence and synteny next to the neurodevelopmental gene Slitrk3. RUS is exclusively expressed in neural cells and its expression increases along with neuronal markers during neuronal differentiation of mouse embryonic cortical neural stem cells. Depletion of RUS locks neuronal precursors in an intermediate state towards neuronal differentiation, with arrested cell cycle and increased apoptosis. RUS associates with chromatin in the vicinity of genes involved in neurogenesis, most of which change their expression upon RUS depletion. The identification of a range of epigenetic regulators as specific RUS interactors suggests that the lncRNA may mediate gene activation and repression in a highly context-dependent manner.
Project description:Small RNAs target their complementary chromatin regions for gene silencing through nascent long non-coding RNAs (lncRNAs). In programmed DNA elimination of the ciliated protozoan Tetrahymena, the interaction between Piwi-associated small RNA (scnRNAs) and the lncRNA transcripts from the somatic genome has been proposed to induce target-directed scnRNA degradation (TDSD) and scnRNAs not targeted for TDSD later target the germline-limited sequences for DNA elimination. In this study, we show that the SUMO E3 ligase Ema2 is required for the accumulation of lncRNAs from somatic genome, and thus for TDSD and completing DNA elimination to make viable sexual progeny. Ema2 interacts with the SUMO E2 conjugating enzyme Ubc9 and enhances SUMOylation of the transcription regulator Spt6. We further show that Ema2 promotes the association of Spt6 and RNA polymerase II to chromatin. These results suggest that Ema2-directed SUMOylation actively promotes the lncRNA transcription that is a prerequisite for communication between the genome and small RNAs.