Dataset Information

Multi-level profiling unravels mitochondrial dysfunction in Myotonic Dystrophy type 2

ABSTRACT: 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.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Skeletal Muscle

SUBMITTER: Andreas Hentschel

LAB HEAD: Andreas Hentschel

PROVIDER: PXD044286 | Pride | 2024-01-26

REPOSITORIES: Pride

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Multi-level profiling unravels mitochondrial dysfunction in myotonic dystrophy type 2.

Kleefeld Felix F Horvath Rita R Pinal-Fernandez Iago I Mammen Andrew L AL Casal-Dominguez Maria M Hathazi Denisa D Melchert Sarah S Hahn Katrin K Sickmann Albert A Muselmann-Genschow Claudia C Hentschel Andreas A Preuße Corinna C Roos Andreas A Schoser Benedikt B Stenzel Werner W

Acta neuropathologica 20240119 1

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 has resulted in new insights into disease mechanisms and identified mitochondrial dys ...[more]

PMID: 38240888

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Project description:Caloric Restriction in Leptin Deficiency Worsens Myocardial Steatosis: Failure to Upregulate PPAR gamma and Thermogenic Glyecrolipid/Fatty Acid Cycling Growing evidence supports an anti-lipotoxic role for leptin in preventing inappropriate peripheral tissue lipid deposition. Obese, leptin deficient ob/ob mice develop left ventricular (LV) hypertrophy and myocardial steatosis with increased apoptosis and decreased longevity. Here we investigated the cardiac effects of caloric restriction in leptin deficiency. Echocardiography was performed on C57Bl/6 wild-type mice (WT) and 7-month-old ob/ob mice fed ad lib, leptin-repleted (LR-ob/ob), or calorie-restricted (CR-ob/ob) for four weeks. Ventricular tissue was examined by electron microscopy (EM), mitochondrial coupling assay, and microarray expression profiling. LR and CR-ob/ob mice showed decreased body weight, heart weight, and LV wall thickness compared to ad lib ob/ob mice. LV fractional shortening was decreased in ad lib ob/ob mice, but restored to WT levels in LR and CR groups. However, EM revealed severe cardiac steatosis in the CR-ob/ob group compared to only moderate steatosis in ad lib ob/ob . Despite marked cardiac steatosis, CR (like LR) restored mitochondrial coupling to WT levels. CR up-regulated genes associated with oxidative stress and cell death, changes suggestive of cardiac lipotoxicity. LR, but not CR was shown to induce core genes involved in glycerolipid/free fatty acid cycling, a highly thermogenic pathway that can reduce intracellular lipid stores. LR, but not CR up-regulated and restored PGC1 and PPARto wild type levels; CR paradoxically further suppressed cardiac PPAR. Thus, leptin is essential in protecting the heart from lipotoxicity, and the inability to up-regulate the thermogenic glycerolipid/free fatty acid cycling pathway may impair the response of leptin deficient animals to the lipotoxic stress of calorie restriction. 6 month aged ob/ob mice were either leptin repleted with osmotic mini-pumps, calorie restricted to match the caloric intake of the leptin repleted mice, or fed ad lib for one month. 6-8 month C57Bl/6J mice were aged to serve as controls.

Dataset Information

Multi-level profiling unravels mitochondrial dysfunction in Myotonic Dystrophy type 2

Publications

Multi-level profiling unravels mitochondrial dysfunction in myotonic dystrophy type 2.

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