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: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:Cytoplasmic long non coding RNAs have been shown to act at many different levels to control post-transcriptional gene expression; though their role in translational control is still poorly understood. Here we show that lnc-31 is a translational activator of Rock1, a negative regulator of myogenesis which prevents the exit of myoblasts from the cell cycle. This activity well correlates with the described role of lnc-31 in supporting myoblast proliferation. We show that lnc-31 binds the translational regulator YB-1 and targets the Rock1 mRNA by direct base pair interaction. We present evidences that lnc-31 stabilizes YB-1 on the Rock1 mRNA; this effect would in turn allow the YB-1-dependent remodelling of the Rock1 5’UTR and the promotion of its translation.
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.
Project description:Long non-coding RNAs (lncRNAs) regulate vital biological processes, including cell proliferation, differentiation and development. A subclass of lncRNAs is synthesized from microRNA host genes (MIRHGs) due to pre-miRNA processing, and is categorized as miRNA-host gene lncRNAs (lnc-miRHGs). Presently, it is not clear whether lnc-miRHG perform additional functions. We demonstrate a miRNA-independent role for a nuclear-enriched lnc-miRHG in cell cycle progression. MIR100HG produces spliced and stable lncRNAs (lnc-MIR100HG) that display elevated levels during the G1 phase of the cell cycle. Depletion of lnc-MIR100HG in human cells results in aberrant cell cycle progression with out altering the levels of miRNA encoded within MIR100HG. Notably, lnc-MIR100HG interacts with the HuR/Elav as well as with several of HuR-target mRNAs. Further, lnc-MIR100HG-depleted cells show reduced interaction between HuR and its target mRNAs, indicating that lnc-MIR100HG facilitates interaction between HuR and target mRNAs. Our studies have unearthed novel roles played by miRHG-encoded lncRNAs in regulating RNA binding protein activity, thereby underscoring the importance of determining the function of several hundreds of miRHG lncRNAs that are present in human genome.
Project description:Long non-coding RNAs (lncRNAs) regulate vital biological processes, including cell proliferation, differentiation and development. A subclass of lncRNAs is synthesized from microRNA host genes (MIRHGs) due to pre-miRNA processing, and is categorized as miRNA-host gene lncRNAs (lnc-miRHGs). Presently, it is not clear whether lnc-miRHG perform additional functions. We demonstrate a miRNA-independent role for a nuclear-enriched lnc-miRHG in cell cycle progression. MIR100HG produces spliced and stable lncRNAs (lnc-MIR100HG) that display elevated levels during the G1 phase of the cell cycle. Depletion of lnc-MIR100HG in human cells results in aberrant cell cycle progression with out altering the levels of miRNA encoded within MIR100HG. Notably, lnc-MIR100HG interacts with the HuR/Elav as well as with several of HuR-target mRNAs. Further, lnc-MIR100HG-depleted cells show reduced interaction between HuR and its target mRNAs, indicating that lnc-MIR100HG facilitates interaction between HuR and target mRNAs. Our studies have unearthed novel roles played by miRHG-encoded lncRNAs in regulating RNA binding protein activity, thereby underscoring the importance of determining the function of several hundreds of miRHG lncRNAs that are present in human genome.
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.