Project description:Myotonic dystrophy is caused by expanded CTG/CCTG microsatellite repeats, leading to multi-systemic symptoms in skeletal muscle, heart, gastrointestinal, endocrine, and central nervous systems (CNS), among others. For many patients, CNS issues can be as or more debilitating than muscle symptoms; they include hypersomnolence, executive dysfunction, white matter atrophy, and neurofibrillary tangles. Although transcriptomes from DM1 skeletal muscle have provided useful insights into pathomechanisms and biomarkers, similarly extensive studies have not yet been performed in the CNS. To elucidate underlying causes of CNS dysfunction in patients, we have generated and analyzed RNA-seq transcriptomes from the frontal cortex of 21 DM1 patients, 4 DM2 patients, and 8 unaffected controls. One hundred and thirty high confidence splicing changes were identified, many occurring exclusively in the CNS and not in the periphery. Mis-spliced exons were found in neurotransmitter receptors, ion channels, and synaptic scaffolds, and we identified an alternative exon in GRIP1 that modulates association with kinesins. Splicing changes exhibited a gradient of severity correlating with CTG repeat length, as measured by optical mapping of individual DNA molecules. All individuals studied, including those with modest splicing defects, showed a subset of alleles with repeats longer than 1000 CTGs. Analyses of gene expression changes showed up-regulation of genes transcribed in microglia and endothelial cells, suggesting neuroinflammation, and down-regulation of genes transcribed in neurons. Gene expression changes for RNAs encoding proteins detectable in CSF were also found to correlate with mis-splicing, with implications for CNS biomarkers of disease severity. These findings provide a framework for future mechanistic and therapeutic studies of CNS issues in DM.
Project description:Misregulated alternative splicing appears to be a major factor in the pathogenesis of myotonic dystrophy. The present study was done to further explore alternative splicing in this condition by doing exon-level analysis of mRNA from skeletal muscle of 8 subjects with type 1 myotonic dystrophy, 7 subjects with type 2 myotonic dystrophy, 8 disease controls (subjects with facioscapulohumeral muscular dystrophy), and 8 healthy controls . The ratios of signals from the various exons of a gene provided an index of altered exon inclusion/exclusion that was independent of the overall expression of that gene. There were numerous transcripts for which there was evidence of abnormal alternative splicing in subjects with myotonic dystrophy. For many of these transcripts, the abnormal splicing was confirmed by an independent RT-PCR approach. 31 subjects, one sample per subject, four groups: healthy subjects (n = 8), facioscapulohumeral dystrophy (n = 8), type 1 myotonic dystrophy (n = 8), type 2 myotonic dystrophy (n = 7)
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 is a dominantly inherited multisystemic disease caused by CTG tandem repeat expansions in the DMPK 3' untranslated region. These expanded repeats are transcribed and produce toxic CUG RNAs that sequester and inhibit activities of the MBNL family of developmental RNA processing factors. Although myotonic dystrophy is classified as a muscular dystrophy, the brain is also severely affected by an unusual cohort of symptoms, including hypersomnia, executive dysfunction, as well as early onsets of tau/MAPT pathology and cerebral atrophy. To address the molecular and cellular events that lead to these pathological outcomes, we recently generated a mouse Dmpk CTG expansion knockin model and identified choroid plexus epithelial cells as particularly affected by the expression of toxic CUG expansion RNAs. To determine if toxic CUG RNAs perturb choroid plexus functions, alternative splicing analysis was performed on lateral and hindbrain choroid plexi from Dmpk CTG knockin mice. Choroid plexus transcriptome-wide changes were evaluated in Mbnl2 knockout mice, a developmental-onset model of myotonic dystrophy brain dysfunction. To determine if transcriptome changes also occurred in the human disease, we obtained post-mortem choroid plexus for RNA-seq from donors without neurologically unaffected (two females, three males; ages 50-70) and myotonic dystrophy type 1 donors (one female, three males; ages 50-70). To test that choroid plexus transcriptome alterations resulted in altered CSF composition, we obtained CSF via lumbar puncture from patients with myotonic dystrophy type 1 (five females, five males; ages 35-55) and non-myotonic dystrophy patients (three females, four males; ages 26-51) and Western blot and osmolarity analyses were used to test CSF alterations predicted by choroid plexus transcriptome analysis. We determined that CUG RNA induced toxicity was more robust in the lateral choroid plexus of Dmpk CTG knockin mice due to comparatively higher Dmpk and lower Mbnl RNA levels. Impaired transitions to adult splicing patterns during choroid plexus development were identified in Mbnl2 knockout mice, including mis-splicing previously found in Dmpk CTG knockin mice. Whole transcriptome analysis of myotonic dystrophy type 1 choroid plexus revealed disease-associated RNA expression and mis-splicing events. Based on these RNA changes, predicted alterations in ion homeostasis, secretory output, and CSF composition were confirmed by analysis of myotonic dystrophy type 1 CSF. Our results implicate choroid plexus spliceopathy and concomitant alterations in CSF homeostasis as an unappreciated contributor to myotonic dystrophy type 1 CNS pathogenesis.
Project description:Myotonic dystrophy type 1 is a dominantly inherited multisystemic disease caused by CTG tandem repeat expansions in the DMPK 3' untranslated region. These expanded repeats are transcribed and produce toxic CUG RNAs that sequester and inhibit activities of the MBNL family of developmental RNA processing factors. Although myotonic dystrophy is classified as a muscular dystrophy, the brain is also severely affected by an unusual cohort of symptoms, including hypersomnia, executive dysfunction, as well as early onsets of tau/MAPT pathology and cerebral atrophy. To address the molecular and cellular events that lead to these pathological outcomes, we recently generated a mouse Dmpk CTG expansion knockin model and identified choroid plexus epithelial cells as particularly affected by the expression of toxic CUG expansion RNAs. To determine if toxic CUG RNAs perturb choroid plexus functions, alternative splicing analysis was performed on lateral and hindbrain choroid plexi from Dmpk CTG knockin mice. Choroid plexus transcriptome-wide changes were evaluated in Mbnl2 knockout mice, a developmental-onset model of myotonic dystrophy brain dysfunction. To determine if transcriptome changes also occurred in the human disease, we obtained post-mortem choroid plexus for RNA-seq from donors without neurologically unaffected (two females, three males; ages 50-70) and myotonic dystrophy type 1 donors (one female, three males; ages 50-70). To test that choroid plexus transcriptome alterations resulted in altered CSF composition, we obtained CSF via lumbar puncture from patients with myotonic dystrophy type 1 (five females, five males; ages 35-55) and non-myotonic dystrophy patients (three females, four males; ages 26-51) and Western blot and osmolarity analyses were used to test CSF alterations predicted by choroid plexus transcriptome analysis. We determined that CUG RNA induced toxicity was more robust in the lateral choroid plexus of Dmpk CTG knockin mice due to comparatively higher Dmpk and lower Mbnl RNA levels. Impaired transitions to adult splicing patterns during choroid plexus development were identified in Mbnl2 knockout mice, including mis-splicing previously found in Dmpk CTG knockin mice. Whole transcriptome analysis of myotonic dystrophy type 1 choroid plexus revealed disease-associated RNA expression and mis-splicing events. Based on these RNA changes, predicted alterations in ion homeostasis, secretory output, and CSF composition were confirmed by analysis of myotonic dystrophy type 1 CSF. Our results implicate choroid plexus spliceopathy and concomitant alterations in CSF homeostasis as an unappreciated contributor to myotonic dystrophy type 1 CNS pathogenesis.
Project description:Misregulated alternative splicing appears to be a major factor in the pathogenesis of myotonic dystrophy. The present study was done to further explore alternative splicing in this condition by doing exon-level analysis of mRNA from skeletal muscle of 8 subjects with type 1 myotonic dystrophy, 7 subjects with type 2 myotonic dystrophy, 8 disease controls (subjects with facioscapulohumeral muscular dystrophy), and 8 healthy controls . The ratios of signals from the various exons of a gene provided an index of altered exon inclusion/exclusion that was independent of the overall expression of that gene. There were numerous transcripts for which there was evidence of abnormal alternative splicing in subjects with myotonic dystrophy. For many of these transcripts, the abnormal splicing was confirmed by an independent RT-PCR approach.
Project description:Myotonic dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy caused by expansion of a CTG repeat microsatellite within DMPK. In 10-20% of individuals with DM1, symptomatic onset begins at birth; these patients are classified as congenital myotonic dystrophy (CDM). While dysregulation of RNA metabolism, specifically alternative splicing, has been linked to disease pathology in adult-onset DM1, little is known about the mechanism of CDM. Biopsies from individuals (CDM), age range 0.04-16 years, were subjected to total RNA-seq to quantify the transcriptomic dysregulation throughout pediatric development. To achieve this, they were compared against age matched pediatric controls which revealed a triphasic pattern of dysregulation not before seen observed in CDM. CDM samples were also compared to adult-onset (DM1) individuals which showcased a shared disease signature to seen in all individuals with myotonic dystrophy irrespective of disease age of onset.
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