Project description:Myotonic Dystrophy Type-2 (DM2) is an autosomal dominant disease caused by the expansion of a CCTG tetraplet repeat. It is a multisystemic disorder, affecting skeletal muscles, the heart, the eye, the central nervous system and the endocrine system The expression of 365 miRNAs was measured in the muscle of DM2 patients and compared it to controls and were identified distinct miRNAs modulated in DM2 patients compared to controls. Our study included 10 DM2 and 9 control (CTR) muscle biopsies from biceps brachii. DM2 and CTR were age- and sex- matched. Most DM2 patients had myotonia and cataract, two disease hallmarks, while differences in other clinical parameters (muscle strenght, diabetes, CPK, FT3, FT4, TSH, ejection fraction) were not significant. miRNAs expression was assessed by Applied Biosystems Human TaqMan Low Density Array (TLDA, v1.0).
Project description:Myotonic Dystrophy Type-2 (DM2) is an autosomal dominant disease caused by the expansion of a CCTG tetraplet repeat. It is a multisystemic disorder, affecting skeletal muscles, the heart, the eye, the central nervous system and the endocrine system. Whole mRNAs expression was measured in the muscle of DM2 patients and compared it to controls.We identified distinct genes modulated in DM2 patients compared to controls. Our study included 10 DM2 and 10 control (CTR) muscle biopsies from biceps brachii. DM2 and CTR were age- and sex- matched. Most DM2 patients had myotonia and cataract, two disease hallmarks, while differences in other clinical parameters (muscle strenght, diabetes, CPK, FT3, FT4, TSH, ejection fraction) were not significant. Genes expression was assessed by Affymetrix Gene Chip Human Exon 1.0 ST Array.
Project description:The prevailing patho-mechanistic paradigm for myotonic dystrophy (DM) is that the aberrant presence of embryonic isoforms is responsible for many, if not most, aspects of the pleiotropic disease phenotype. In order to identify such aberrantly expressed isoforms in skeletal muscle of DM type 1 (DM1) and type 2 (DM2) patients, we utilized the Affymetrix exon array to characterize the largest collection of DM samples analyzed to date, and included non-DM dystrophic muscle samples (NMD) as disease controls. For the exon array profiling on the Human Exon 1.0 ST array (Affymetrix Santa Clara, CA) we used a panel of 28 skeletal muscle biopsies from DM1 (n=8), DM2 (n=10), Becker muscular dystrophy, BMD, (n=3), Duchenne muscular dystrophy, DMD (n=1), Tibial muscular dystrophy, TMD, (n=2) and normal skeletal muscle (n=4). Normal control RNAs were purchased commercially. .CEL files were generated with a pre-commercial version of the Affymetrix processing software, and the headers might be non-standard. In our lab, users of the Partek software could use them, whereas users of GeneSpring had to modify the header information.
Project description:Myotonic Dystrophy type 2 (DM2) is an autosomal-dominant, multisystemic disease with a core manifestation of proximal muscle weakness, muscle atrophy, myotonia, and myalgia. The disease-causing CCTG tetranucleotide expansion within the CNBP gene on chromosome 3 leads to an RNA-dominated spliceopathy which is currently untreatable. Research exploring the pathophysiological mechanisms in Myotonic Dystrophy Type 1 resulted in new insights into disease mechanisms and identified mitochondrial dysfunction as promising therapeutic target. It remains unclear whether similar mechanisms underlie DM2 and, if so, whether these might also serve as potential therapeutic targets. In this cross-sectional study, we studied DM2 skeletal muscle biopsy specimens on proteomic, molecular, and morphological including ultrastructural levels in two separate patient cohorts consisting of 8 (explorative cohort) and 40 (confirmatory cohort) patients. Seven muscle biopsy specimens obtained from four female and three male DM2 patients underwent proteomic analysis. We performed immunoblotting of respiratory chain complexes, mitochondrial DNA copy number determination and long-range PCR (LR-PCR) to study mitochondrial deletions on six biopsies. Forty-eight biopsy samples were studied by light and electron microscopy. Proteomic analysis revealed a downregulation of essential mitochondrial proteins, namely of subunits of respiratory chain complexes I, III, and IV (e.g. mt-CO1, mt-ND1, mt-CYB, NDUFB6) and associated translation factors (TACO1). Light microscopy showed an age-inappropriate amount of COX-deficient fibers in most biopsy specimens. Electron microscopy revealed widespread ultrastructural mitochondrial abnormalities including dysmorphic mitochondria with paracrystalline inclusions. Immunoblotting and LR-PCR did not reveal significant differences between patients and controls, while mtDNA-copy number measurement revealed a reduction of mtDNA-copy numbers in the patient group compared to controls. This first multi-level study of DM2 unravels thus far undescribed functional and structural mitochondrial abnormalities. While the molecular link between the tetranucleotide expansion, and mitochondrial dysfunction needs to be further elucidated, these findings may provide an additional route for treatment strategies for DM2.
Project description:Myotonic Dystrophy Type-2 (DM2) is an autosomal dominant disease caused by the expansion of a CCTG tetraplet repeat. It is a multisystemic disorder, affecting skeletal muscles, the heart, the eye, the central nervous system and the endocrine system The expression of 365 miRNAs was measured in the muscle of DM2 patients and compared it to controls and were identified distinct miRNAs modulated in DM2 patients compared to controls.
Project description:Myotonic Dystrophy Type-2 (DM2) is an autosomal dominant disease caused by the expansion of a CCTG tetraplet repeat. It is a multisystemic disorder, affecting skeletal muscles, the heart, the eye, the central nervous system and the endocrine system. Whole mRNAs expression was measured in the muscle of DM2 patients and compared it to controls.We identified distinct genes modulated in DM2 patients compared to controls.
Project description:The prevailing patho-mechanistic paradigm for myotonic dystrophy (DM) is that the aberrant presence of embryonic isoforms is responsible for many, if not most, aspects of the pleiotropic disease phenotype. In order to identify such aberrantly expressed isoforms in skeletal muscle of DM type 1 (DM1) and type 2 (DM2) patients, we utilized the Affymetrix exon array to characterize the largest collection of DM samples analyzed to date, and included non-DM dystrophic muscle samples (NMD) as disease controls.
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: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)