Project description:Myotonic dystrophy type 1 (DM1) is a multisystem genetic disorder involving the muscle, heart, and central nervous system (CNS). The pathogenesis of CNS symptoms prevalent in patients with DM1 remains unelucidated. To elucidate the CNS pathogenesis in DM1, we investigated cell type-specific abnormalities in cortical neurons, white matter glial cells, and spinal motor neurons of patients with DM1 via laser-capture microdissection(LCM).
Project description:Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, is caused by the expression of expanded CUG repeats, which sequester the MBNL1 RNA binding protein. Cardiac involvement, which is characterized by conduction defects and arrhythmias, is the second cause of death of DM1 patients. Down-expression of miR-1 in mice leads to cardiac conduction disturbances and to arrhythmias. Here, we show that miR-1 expression is decreased in DM1 hearts, due to a mis-regulation of the processing of pre-miR-1. MBNL1 binds to UGC motifs located within the pre-miR-1 loop and competes binding of LIN28, which promotes uridylation and blocks pre-miR-1 processing. Finally and consistent with a down-regulation of miR-1, known, GJA1, and novel, CACNA1C, targets of miR-1 are increased in DM1 hearts. CACNA1C and GJA1 encode the main calcium and gap junction channels in heart, respectively, and their mis-regulation may contribute to the heart arrythmias and conduction defects observed in DM1 patients. Total RNA of 3 control and 3 CDM1 primary culture of muscle cells differentiated 10 days into myotubes was extracted using Trizol and analyzed by Agilent microarray.
Project description:Myotonic dystrophy type 1 (DM1) is a dominantly inherited disease that affects multiple organ systems. Cardiac dysfunction is the second leading cause of death in DM1. We quantified gene expression in heart tissue from a heart-specific DM1 mouse model (EpA960/MCM) which inducibly expresses human DMPK exon 15 containing 960 CUG expanded repeats and that reproduced Celf1 up regulation. To assess if, in addition to splicing and miRNA defects, CUGexp RNA also perturbed the steady state mRNA levels of genes, we carried out a microarray study on wildtype E14, adult, MCM controls and DM1 mouse hearts. As anticipated we noted a large number of genes to be developmentally regulated in wildtype hearts, however, within 72h of induction of CUGexp RNA there appeared to be a coordinate adult-to-embryonic shift in steady state levels of many genes. We identified transcripts over-expressed or under-expressed in hearts of wildtype adult mice, wildtype embryonic day 14 (E14), and DM1 mice induced to express CUGexp RNA for 72h and 1wk, when compared to MCM controls. Multiple group comparison.
Project description:In this Study, we used RNA-targeting Cas9 (RCas9) to reverse characteristic Myotonic Dystrophy (DM1) cellular phenotypes such as elimination of RNA foci, MBNL relocalization, and reversal of transcriptome-wide splicing in a mouse model of myotonic Dystrophy (DM1). Furthermore we show that gene expression is not altered with RCas9 treatment in WT mice with or without treatment with immunosuppression
Project description:Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, is caused by the expression of expanded CUG repeats, which sequester the MBNL1 RNA binding protein. Cardiac involvement, which is characterized by conduction defects and arrhythmias, is the second cause of death of DM1 patients. Down-expression of miR-1 in mice leads to cardiac conduction disturbances and to arrhythmias. Here, we show that miR-1 expression is decreased in DM1 hearts, due to a mis-regulation of the processing of pre-miR-1. MBNL1 binds to UGC motifs located within the pre-miR-1 loop and competes binding of LIN28, which promotes uridylation and blocks pre-miR-1 processing. Finally and consistent with a down-regulation of miR-1, known, GJA1, and novel, CACNA1C, targets of miR-1 are increased in DM1 hearts. CACNA1C and GJA1 encode the main calcium and gap junction channels in heart, respectively, and their mis-regulation may contribute to the heart arrythmias and conduction defects observed in DM1 patients.
Project description:Myotonic dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy and is caused by an repeat expansion [r(CUG)exp] located in the 3' untranslated region of the DMPK gene. Symptoms include skeletal and cardiac muscle dysfunction and fibrosis. In DM1, there is a lack of established biomarkers in routine clinical practice. Thus, we aimed to identify a blood biomarker with relevance for DM1-pathophysiology and clinical presentation.
Project description:Myotonic dystrophy type 1 (DM1) is a dominantly inherited disease that affects multiple organ systems. Cardiac dysfunction is the second leading cause of death in DM1. We quantified gene expression in heart tissue from a heart-specific DM1 mouse model (EpA960/MCM) which inducibly expresses human DMPK exon 15 containing 960 CUG expanded repeats and that reproduced Celf1 up regulation. To assess if, in addition to splicing and miRNA defects, CUGexp RNA also perturbed the steady state mRNA levels of genes, we carried out a microarray study on wildtype E14, adult, MCM controls and DM1 mouse hearts. As anticipated we noted a large number of genes to be developmentally regulated in wildtype hearts, however, within 72h of induction of CUGexp RNA there appeared to be a coordinate adult-to-embryonic shift in steady state levels of many genes.
Project description:Myotonic dystrophy (DM) is the most common autosomal dominant muscular dystrophy and encompasses both skeletal muscle and cardiac complications. Myotonic dystrophy is nucleotide repeat expansion disorder in which type 1 (DM1) is due to a trinucleotide repeat expansion on chromosome 19 and type 2 (DM2) arises from a tetranucleotide repeat expansion on chromosome 3. Developing representative models of myotonic dystrophy in animals has been challenging due to instability of nucleotide repeat expansions, especially for DM2 which is characterized by nucleotide repeat expansions often greater than 5000 copies. To investigate mechanisms of human DM, we generated cellular models of DM1 and DM2. We used regulated MyoD expression to reprogram urine-derived cells into myotubes. In this cell model, we found impaired dystrophin expression, MBNL foci, and aberrant splicing in DM1 but not in DM2 cells. We generated induced pluripotent stem cells (iPSC) from healthy controls, DM1 and DM2 subjects and differentiated these into cardiomyocytes. DM1 and DM2 cells displayed an increase in RNA foci concomitant with cellular differentiation. IPSC-derived cardiomyocytes from DM1 but not DM2 had aberrant splicing and MBNL sequestration. High resolution imaging revealed tight association between MBNL clusters and RNA FISH foci in DM1. Ca2+ transients differed between DM1 and DM2 IPSC-derived cardiomyocytes and from healthy control cells. RNA-sequencing from DM1 and DM2 iPSC-derived cardiomyocytes both altered gene expression as well as distinct splicing patterns as differential between DM1 and DM2. Together these data support that DM1 and DM2, despite some shared clinical and molecular features, have distinct pathological signatures.
Project description:Autopsy and biopsy muscle and heart tissue was collected from consented human subjects with and without confirmed myotonic dystrophy type 1, myotonic dystrophy type 2, or Duchenne muscular dystrophy. RNA was isolated for preparation of RNAseq libraries and sequenced on the Illumina platform.
Project description:Myotonic dystrophy type 1 (DM1) is a multisystemic genetic disorder caused by a CTG trinucleotide repeat expansion in the 3′ untranslated region of DMPK gene. Heart dysfunctions occur in nearly 80% of DM1 patients and are the second leading cause of disease-related deaths, yet, the underlying mechanisms remain unclear. Herein, we report that upregulation of a non-muscle splice isoform of RNA binding protein RBFOX2 in DM1 heart tissue—due to altered splicing factor and microRNA activities—induces the characteristic cardiac conduction defects detected in DM1 individuals. Mice engineered to express the non-muscle RBFOX2 isoform in heart via tetracycline- inducible transgenesis, or CRISPR/Cas9 targeted genome editing, reproduced DM1- related cardiac-conduction delay and spontaneous episodes of arrhythmia. Furthermore, by integrating RNA binding with cardiac transcriptome datasets of DM1 patients, and mice expressing the non-muscle RBFOX2 isoform, we identified a core network of RBFOX2-driven splicing defects in sodium, potassium, and calcium channels that can alter their rate of ion diffusion and electrophysiological properties. Thus, our results uncover a trans-dominant role for an aberrantly expressed RBFOX2 isoform in DM1 cardiac pathogenesis.