Project description:Steady-state RNA levels are a result of RNA synthesis and degradation. The importance of transcription-factor mediated induction or repression of mRNA synthesis is well established, but the role and mechanisms of RNA degradation are less well understood. We globally evaluated the RNA decay rates in proliferating and differentiated mouse myoblasts on whole-genome Affymetrix exon arrays, allowing for the assessment of directionality of RNA degradation and the detection of splice variant-specific differences in RNA decay rates. We found large differences in decay rates. mRNAs coding for proteins involved in signal transduction and transcriptional regulation have shortest half lives, whereas mRNAs coding for DNA replication enzymes and muscle contraction proteins are among the most stable. Many genes differentially expressed between proliferating and differentiated myoblasts demonstrate major differences in RNA decay rates. Quantitative PCR experiments confirmed the higher stability of transcripts with increased expression levels. RNA degradation has no apparent preferential directionality. RNA degradation appears to affect the ratio of different splice variants. For example, Itga7 isoforms with higher abundance in differentiated than in proliferating cells are more stable in differentiated cells, despite the sharing of a common 3’ untranslated region. Thus, where it was previously thought that the abundance of different splice isoforms was mainly controlled by tissue-specific splicing factors, we now demonstrate that isoforms may be produced at comparable levels but degraded with different efficiencies, depending on the differentiation status of the cells. Our results indicate that control of RNA degradation rates contributes significantly to the differentiation stage-dependent differences in abundance of transcripts and splice variants. Keywords: total RNA expression profiling; cultured cells We analyzed proliferating C2C12 cells and C2C12 cells differentiated into myotubes by serum starvation (8 days after induction of differentiation). We analyzed 7 time points after addition of actionmycin D (0, 10, 20, 30, 60, 150, 480 minutes). There were two biological replicates per condition.
Project description:Steady-state RNA levels are a result of RNA synthesis and degradation. The importance of transcription-factor mediated induction or repression of mRNA synthesis is well established, but the role and mechanisms of RNA degradation are less well understood. We globally evaluated the RNA decay rates in proliferating and differentiated mouse myoblasts on whole-genome Affymetrix exon arrays, allowing for the assessment of directionality of RNA degradation and the detection of splice variant-specific differences in RNA decay rates. We found large differences in decay rates. mRNAs coding for proteins involved in signal transduction and transcriptional regulation have shortest half lives, whereas mRNAs coding for DNA replication enzymes and muscle contraction proteins are among the most stable. Many genes differentially expressed between proliferating and differentiated myoblasts demonstrate major differences in RNA decay rates. Quantitative PCR experiments confirmed the higher stability of transcripts with increased expression levels. RNA degradation has no apparent preferential directionality. RNA degradation appears to affect the ratio of different splice variants. For example, Itga7 isoforms with higher abundance in differentiated than in proliferating cells are more stable in differentiated cells, despite the sharing of a common 3’ untranslated region. Thus, where it was previously thought that the abundance of different splice isoforms was mainly controlled by tissue-specific splicing factors, we now demonstrate that isoforms may be produced at comparable levels but degraded with different efficiencies, depending on the differentiation status of the cells. Our results indicate that control of RNA degradation rates contributes significantly to the differentiation stage-dependent differences in abundance of transcripts and splice variants. Keywords: total RNA expression profiling; cultured cells
Project description:Mutations in genes involved in dNTP metabolism can lead to tissue-specific mitochondrial depletion syndromes (MDS), likely because the expression of key enzymes is reduced to critical levels in post mitotic cells. Our goal was to establish an in vitro skeletal muscle cell model to study the muscle specificity of MDS associated with mitochondrial dNTP pool imbalance. We performed a comprehensive analysis at the mRNA level of enzymes and transporters responsible for dNTP pool imbalance in muscle cells in vitro and in vivo. Agilent Mouse Oligo Arrays 4x44K were utilized to examine expression levels in proliferating and differentiated C2C12 cells as well as in the mouse EDL (fast glycolytic) and soleus (slow oxidative) muscles. The comparison of mRNA expression profiles supports the reliability of our in vitro cell system. Proliferating mouse C2C12 myoblasts were collected at about 50 percent confluence. Myoblasts were then induced to differentiate in vitro into myotubes that were harvested after 96 hours and further purified to reduce the contribution of mononucleated cells present in the culture. Gene expression in C2C12 myoblasts and myotubes was compared with fully differentiated muscle fibers in vivo. To this aim, the extensor digitorum longus (EDL) and soleus hind limb muscles were isolated from adult CD1 mice. These muscles were selected because they have different metabolic (glycolytic vs. oxidative) and twitching (fast vs. slow) properties. Triplicate total RNA samples were submitted to gene expression profiling.
Project description:We newly identified skeletal muscle differentiation-associated miRNAs by comparing miRNA expression profile between C2C12 cell and Wnt4-overexpressing C2C12 cell. miR-487b, miR-3963 and miR-6412 are significantly down-regulated in differentiating C2C12 cells, and transfection of their mimics resulted in reduced expression of myogenic differentiation markers including Troponin T, myosin heavy chain fast and slow type. Single analysis for each condition (proliferating C2C12 cells, differentiating C2C12 cells, proliferating Wnt4-overexpressing C2C12 subline cells
Project description:Wnt/beta-catenin signaling is involved in various aspects of skeletal muscle development and regeneration. Using C2C12 cells, we examined intracellular signaling and gene transcription during myoblast proliferation and differentiation. The results of the present studies suggest that Wnt signaling is interacting with TGF-beta superfamily signaling through Smad activation. Single analysis for each condition (proliferating C2C12 cells, differentiating C2C12 cells, proliferating Wnt4-overexpressing C2C12 subline cells).
Project description:Mutations in genes involved in dNTP metabolism can lead to tissue-specific mitochondrial depletion syndromes (MDS), likely because the expression of key enzymes is reduced to critical levels in post mitotic cells. Our goal was to establish an in vitro skeletal muscle cell model to study the muscle specificity of MDS associated with mitochondrial dNTP pool imbalance. We performed a comprehensive analysis at the mRNA level of enzymes and transporters responsible for dNTP pool imbalance in muscle cells in vitro and in vivo. Agilent Mouse Oligo Arrays 4x44K were utilized to examine expression levels in proliferating and differentiated C2C12 cells as well as in the mouse EDL (fast glycolytic) and soleus (slow oxidative) muscles. The comparison of mRNA expression profiles supports the reliability of our in vitro cell system.
Project description:QKI is required for myelin formation in the verterbrate brain. It functions by binding RNA and regulating its stability, translation, and/or aternative splicing. We have used Affymetrix exon arrays to assess changes in gene expression in response to QKI knockdown on an exon level in rat CG-4 oligodendrocyte precursor cells.
Project description:To investigate microRNAs related to mitochondria biogenesis in skeletal muscle, microRNA expressions during skeletal muscle differentiation and exercise were analyzed in vivo and in vitro. Murine skeletal muscle cell (C2C12) were assigned to undifferentiated, differentiated, and passively stretched (exercise mimicked). C57BL/6S mice were assigned to resting, acute exercise (1day), and chronic exercise (7days). Low molecular weight RNA (< 200 nucleotides) was isolated from C2C12 cell or tibialis anterior muscle of mice and hybridized to Ncode microRNA microarrays. The experiment was performed using a loop design for the data analysis.
Project description:C2C12 myoblasts differentiation is a precise controlled process. Splicing of many genes changes during the differentiation process. Some muscle-specific splicing isoforms play important role in myogenesis. We used microarrays to detail the global programme of gene expression underlying defect of lrrfip1a, a muscle specific splicing isoform of Lrrfip1. Differentiated C2C12 myoblasts shLUCI or shLrrfip1a were collected and extracted RNA, then hybridizated on Affymetrix. We sought to obtain the different expressed genes between shLUCI and shLrrfip1a samples.