Project description:CUG-binding protein 1 (CUGBP1) and muscleblind-like 1 (MBNL1) are developmentally regulated RNA-binding proteins that are causally associated with myotonic dystrophy type 1. We extensively determined RNA-binding sites of CUGBP1 and MBNL1 to investigate their roles in RNA processing. We also analyzed polypyrimidine tract-binding protein (PTB) as a control. CUGBP1 and MBNL1 preferentially bind to alternatively spliced introns and exons, respectively, and regulate alternative splicing events. Moreover, CUGBP1 and MBNL1 are preferentially bound to the 3' untranslated regions (UTRs), in particular of genes for RNA-binding proteins, and facilitate decay of the bound mRNAs. In addition, CUGBP1 and MBNL1 mutually destabilize mRNA. Precise temporal regulation of CUGBP1 and MBNL1 are likely to be essential for accurate control of destabilization of a broad spectrum of genes as well as of alternative splicing events in cell differentiation and tissue development.
Project description:CUGBP1 and MBNL1 are developmentally regulated RNA-binding proteins that are causally associated with myotonic dystrophy type 1. Using HITS-CLIP anlysis, we found CUGBP1 and MBNL1 preferentially bind to alternatively spliced introns and exons, as well as to the 3' UTRs. To analyze more directly the role of CUGBP1/MBNL1 binding in alternative splicing, we performed exon array analysis in C2C12 cells using expression arrays. We analyzed total RNA of C2C12 cells treated with control-, Cugbp1- or Mbnl1-siRNA. RNA was harvested 48 hrs after transfection.
Project description:CUGBP1 and MBNL1 are developmentally regulated RNA-binding proteins that are causally associated with myotonic dystrophy type 1. Using HITS-CLIP anlysis, we found CUGBP1 and MBNL1 preferentially bind to alternatively spliced introns and exons, as well as to the 3' UTRs. To analyze more directly the role of CUGBP1/MBNL1 binding to the 3’ UTR, we performed global analysis of mRNA stability in C2C12 cells using expression arrays, and found that CUGBP1 and MBNL1 regulate decay of endogenous mRNAs. We analyzed total RNA of C2C12 cells treated with control-, Cugbp1- or Mbnl1-siRNA. We analyzed 3 time points after addition of actionmycin D (0, 2.5, 5 hours).
Project description:CUGBP1 and MBNL1 are developmentally regulated RNA-binding proteins that are causally associated with myotonic dystrophy type 1. Using HITS-CLIP anlysis, we found CUGBP1 and MBNL1 preferentially bind to alternatively spliced introns and exons, as well as to the 3' UTRs. To analyze more directly the role of CUGBP1/MBNL1 binding to the 3’ UTR, we performed global analysis of mRNA stability in C2C12 cells using expression arrays, and found that CUGBP1 and MBNL1 regulate decay of endogenous mRNAs. Overall design: We analyzed total RNA of C2C12 cells treated with control-, Cugbp1- or Mbnl1-siRNA. We analyzed 3 time points after addition of actionmycin D (0, 2.5, 5 hours).
Project description:Muscleblind-like 1 (MBNL1) is a ubiquitously expressed RNA-binding protein, which is highly expressed in skeletal muscle. Abnormally expanded CUG-repeats in the DMPK gene cause myotonic dystrophy type 1 (DM1) by sequestration of MBNL1 to nuclear RNA foci and by upregulation of another RNA-binding protein, CUG-binding protein 1 (CUGBP1). We previously reported that a nonsteroidal anti-inflammatory drug (NSAID), phenylbutazone, upregulates MBNL1 expression in DM1 mouse model by demethylation of MeR2, an enhancer element in Mbnl1 intron 1. NSAIDs inhibit cyclooxygenase (COX), which is comprised of COX-1 and COX-2 isoforms. In this study, we screened 29 NSAIDs in C2C12 myoblasts, and found that 13 NSAIDs enhanced Mbnl1 expression, where COX-1-selective NSAIDs upregulated Mbnl1 more than COX-2-selective NSAIDs. Consistently, knockdown of COX-1, but not of COX-2, upregulated MBNL1 expression in C2C12 myoblasts and myotubes, as well as in myotubes differentiated from DM1 patient-derived induced pluripotent stem cells (iPSCs). Luciferase assay showed that COX-1-knockdown augmented the MeR2 enhancer activity. Furthermore, bisulfite sequencing analysis demonstrated that COX-1-knockdown suppressed methylation of MeR2. These results suggest that COX-1 inhibition upregulates Mbnl1 transcription through demethylation of the MeR2 enhancer. Taken together, our study provides new insights into the transcriptional regulation of Mbnl1 by the COX-1-mediated pathway.
Project description:Skeletal myogenesis is a highly ordered and complex biological process that is mediated by numerous regulatory factors. In previous studies, it has been demonstrated that microRNAs (miRs) and long non?coding RNAs (lncRNAs) serve key roles in skeletal myogenesis. The present study showed that the expression levels of miR?23a?5p showed a dynamic change from decrease to increase during C2C12 myoblast proliferation and differentiation. Functional analysis using 5?ethynyl?2'?deoxyuridine proliferation and Cell Counting Kit?8 detection assays indicated that overexpression of miR?23a?5p significantly promoted C2C12 myoblast proliferation compared with the negative control. In addition, in C2C12 myoblasts transfected with miR?23a?5p mimics, increased expression levels of regulators associated with cell proliferation (Cyclin E, CCND1 and Cyclin B) were observed compared with the negative control. By contrast, overexpression of miR?23a?5p decreased the expression levels of specific?myogenesis factors (MyoD, MyoG and Myf5) and decreased C2C12 myoblast differentiation. Luciferase activity assays indicated that miR?23a?5p suppressed the luciferase activity of lncDum. Further analysis demonstrated that miR?23a?5p not only showed an opposite expression level pattern compared with lncDum, which was first increased and then decreased, but also had an opposite effect on the proliferation and differentiation of C2C12 myoblasts compared with lncDum which inhibited cell proliferation and promoted cell differentiation. Taken together, these results indicated that miR?23a?5p may mediate the proliferation and differentiation of C2C12 myoblasts, which may be involved in lncDum regulation.
Project description:The differentiation of myoblasts plays a key role in the growth of biological individuals and the reconstruction of muscle tissue. Several microRNAs are significantly upregulated during the differentiation of myoblasts and their target genes have been explored. However, the molecular mechanisms underlying the transcriptional regulation of microRNAs remain elusive. In the present study, we found that the expression of miR-133a is increased during the differentiation of C2C12 myoblasts. miR-133a mimic is sufficient to induce the biogenesis of mitochondria and differentiation of C2C12 myoblasts whereas miR-133a inhibitor abolishes cell differentiation. Using CRISPR affinity purification in situ of regulatory elements (CAPTURE) technique, we further dissected the regulatory mechanisms of miR-133a expression and found that KAP1-associated transcription complex accounts for the suppression of miR-133a in C2C12 myoblasts. Knockdown of KAP1 increased the expression of miR-133a, which contributed to the biogenesis of mitochondria and differentiation of C2C12 myoblasts. To our knowledge, this is the first study using the CAPTURE technology to identify the regulatory factors of miR-133a during cell differentiation, which may provide new ideas for understanding the precision regulatory machinery of microRNAs during different biological processes.
Project description:The kinase Mirk/dyrk1B is essential for the differentiation of C2C12 myoblasts. Mirk reinforces the G0/G1 arrest state in which differentiation occurs by directly phosphorylating and stabilizing p27(Kip1) and destabilizing cyclin D1. We now demonstrate that Mirk is anti-apoptotic in myoblasts. Knockdown of endogenous Mirk by RNA interference activated caspase 3 and decreased myoblast survival by 75%, whereas transient overexpression of Mirk increased cell survival. Mirk exerts its anti-apoptotic effects during muscle differentiation at least in part through effects on the cell cycle inhibitor and pro-survival molecule p21(Cip1). Overexpression and RNA interference experiments demonstrated that Mirk phosphorylates p21 within its nuclear localization domain at Ser-153 causing a portion of the typically nuclear p21 to localize in the cytoplasm. Phosphomimetic GFP-p21-S153D was pancellular in both cycling C2C12 myoblasts and NIH3T3 cells. Endogenous Mirk in myotubes and overexpressed Mirk in NIH3T3 cells were able to cause the pancellular localization of wild-type GFP-p21 but not the nonphosphorylatable mutant GFP-p21-S153A. Translocation to the cytoplasm enables p21 to block apoptosis through inhibitory interaction with pro-apoptotic molecules. Phosphomimetic p21-S153D was more effective than wild-type p21 in blocking the activation of caspase 3. Transient expression of p21-S153D also increased myoblast viability in colony forming assays, whereas the p21-S153A mutant had no effect. This Mirk-dependent change in p21 intracellular localization is a natural part of myoblast differentiation. Endogenous p21 localized exclusively to the nuclei of proliferating myoblasts but was also found in the cytoplasm of post-mitotic multinucleated myotubes and adult human skeletal myofibers.
Project description:MicroRNAs (miRNAs) have been reported that can regulate skeletal muscle growth and development. Previously, we demonstrated that miR-127-3p were differently expressed in skeletal muscle and muscle cells. However, the molecular mechanism of miR-127-3p regulation of skeletal myogenesis are not well elucidated. In this study, we transfected miR-127-3p into C2C12 cells, and found miR-127-3p induces myogenesis by targeting Vamp2. Moreover, the regulatory mechanism of Vamp2 in myoblasts proliferation and differentiation was further confirmed. In conclusion, our data providedevidences that miR-127-3p reciprocally regulated myoblasts proliferation and differentiation through directly targeting Vamp2.
Project description:Synthetic cathinones are popular psychoactive substances that may cause skeletal muscle damage. In addition to indirect sympathomimetic myotoxicity, these substances could be directly myotoxic. Since studies in myocytes are currently lacking, the aim of the present study was to investigate potential toxicological effects by synthetic cathinones on C2C12 myoblasts (mouse skeletal muscle cell line). We exposed C2C12 myoblasts to 3-methylmethcathinone, 4-methylmethcathinone (mephedrone), 3,4-methylenedioxymethcathinone (methylone), 3,4-methylenedioxypyrovalerone (MDPV), alpha-pyrrolidinovalerophenone (α-PVP), and naphthylpyrovalerone (naphyrone) for 1 or 24 h before cell membrane integrity, ATP content, mitochondrial oxygen consumption, and mitochondrial superoxide production was measured. 3,4-Methylenedioxymethamphetamine (MDMA) was included as a reference compound. All investigated synthetic cathinones, as well as MDMA, impaired cell membrane integrity, depleted ATP levels, and increased mitochondrial superoxide concentrations in a concentration-dependent manner in the range of 50⁻2000 μM. The two pyrovalerone derivatives α-PVP and naphyrone, and MDMA, additionally impaired basal and maximal cellular respiration, suggesting mitochondrial dysfunction. Alpha-PVP inhibited complex I, naphyrone complex II, and MDMA complex I and III, whereas complex IV was not affected. We conclude that, in addition to sympathetic nervous system effects and strenuous muscle exercise, direct effects of some cathinones on skeletal muscle mitochondria may contribute to myotoxicity in susceptible synthetic cathinone drugs users.