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Zhong Nan Da Xue Xue Bao. Yi Xue Ban =... Nov 2023Mitochondrial myopathy is a group of multi-system diseases in which mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) defects lead to structural and functional dysfunction...
Mitochondrial myopathy is a group of multi-system diseases in which mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) defects lead to structural and functional dysfunction of mitochondria. The clinical manifestations of mitochondrial myopathy are complex and varied, and the testing for mtDNA and nDNA is not widely available, so misdiagnosis or missed diagnosis is common. Chronic progressive external ophthalmoplegia (CPEO) is a common type of mitochondrial myopathy, which is characterized by blepharoptosis. Here we report a 38-year-old female with mitochondrial myopathy presented with chronic numbness and weakness of the limbs, accompanied by blepharoptosis that was recently noticed. Laboratory and head magnetic resonance imaging (MRI) examinations showed no obvious abnormalities. Muscle and nerve biopsies showed characteristic ragged red fibers (RRFs) and large aggregates of denatured mitochondria. Testing for mtDNA and nDNA showed a known mutation c.2857C>T (p.R953C) and a novel variant c.2391G>C (p.M797I) in the polymerase gamma ()gene, so the patient was diagnosed as mitochondrial myopathy. Clinicians should pay more attention to long-term unexplained skeletal muscle diseases with recent onset blepharoptosis. Histopathologic examination and genetic testing are of great value in the early diagnosis and therapeutic intervention.
Topics: Female; Humans; Adult; Blepharoptosis; Mitochondrial Myopathies; Ophthalmoplegia, Chronic Progressive External; DNA, Mitochondrial; Mitochondria
PubMed: 38432868
DOI: 10.11817/j.issn.1672-7347.2023.220605 -
Nature Genetics Mar 2024In digenic inheritance, pathogenic variants in two genes must be inherited together to cause disease. Only very few examples of digenic inheritance have been described...
In digenic inheritance, pathogenic variants in two genes must be inherited together to cause disease. Only very few examples of digenic inheritance have been described in the neuromuscular disease field. Here we show that predicted deleterious variants in SRPK3, encoding the X-linked serine/argenine protein kinase 3, lead to a progressive early onset skeletal muscle myopathy only when in combination with heterozygous variants in the TTN gene. The co-occurrence of predicted deleterious SRPK3/TTN variants was not seen among 76,702 healthy male individuals, and statistical modeling strongly supported digenic inheritance as the best-fitting model. Furthermore, double-mutant zebrafish (srpk3; ttn.1) replicated the myopathic phenotype and showed myofibrillar disorganization. Transcriptome data suggest that the interaction of srpk3 and ttn.1 in zebrafish occurs at a post-transcriptional level. We propose that digenic inheritance of deleterious changes impacting both the protein kinase SRPK3 and the giant muscle protein titin causes a skeletal myopathy and might serve as a model for other genetic diseases.
Topics: Animals; Humans; Male; Connectin; Muscle, Skeletal; Muscular Diseases; Mutation; Zebrafish
PubMed: 38429495
DOI: 10.1038/s41588-023-01651-0 -
European Journal of Cell Biology Jun 2024Desmin gene mutations cause myopathies and cardiomyopathies. Our previously characterised R349P desminopathy mice, which carry the ortholog of the common human desmin...
Desmin gene mutations cause myopathies and cardiomyopathies. Our previously characterised R349P desminopathy mice, which carry the ortholog of the common human desmin mutation R350P, showed marked alterations in mitochondrial morphology and function in muscle tissue. By isolating skeletal muscle myoblasts from offspring of R349P desminopathy and p53 knock-out mice, we established an immortalised cellular disease model. Heterozygous and homozygous R349P desmin knock-in and wild-type myoblasts could be well differentiated into multinucleated spontaneously contracting myotubes. The desminopathy myoblasts showed the characteristic disruption of the desmin cytoskeleton and desmin protein aggregation, and the desminopathy myotubes showed the characteristic myofibrillar irregularities. Long-term electrical pulse stimulation promoted myotube differentiation and markedly increased their spontaneous contraction rate. In both heterozygous and homozygous R349P desminopathy myotubes, this treatment restored a regular myofibrillar cross-striation pattern as seen in wild-type myotubes. High-resolution respirometry of mitochondria purified from myotubes by density gradient ultracentrifugation revealed normal oxidative phosphorylation capacity, but a significantly reduced proton leak in mitochondria from the homozygous R349P desmin knock-in cells. Consistent with a reduced proton flux across the inner mitochondrial membrane, our quantitative proteomic analysis of the purified mitochondria revealed significantly reduced levels of ADP/ATP translocases in the homozygous R349P desmin knock-in genotype. As this alteration was also detected in the soleus muscle of R349P desminopathy mice, which, in contrast to the mitochondria purified from cultured cells, showed a variety of other dysregulated mitochondrial proteins, we consider this finding to be an early step in the pathogenesis of secondary mitochondriopathy in desminopathy.
Topics: Animals; Desmin; Mice; Muscle Fibers, Skeletal; Gene Knock-In Techniques; Protons; Mitochondria; Muscular Dystrophies; Cardiomyopathies
PubMed: 38412640
DOI: 10.1016/j.ejcb.2024.151399 -
Annals of Transplantation Feb 2024BACKGROUND Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE) is an autosomal recessive disease caused by thymidine phosphorylase deficiency leading to...
BACKGROUND Mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE) is an autosomal recessive disease caused by thymidine phosphorylase deficiency leading to progressive gastrointestinal dysmotility, cachexia, ptosis, ophthalmoparesis, peripheral neuropathy and leukoencephalopathy. Although liver transplantation corrects thymidine phosphorylase deficiency, intestinal deficiency of the enzyme persists. Retrospective chart review was carried out to obtain clinical, biochemical, and pathological details. CASE REPORT We present a case of liver and subsequent intestine transplant in a 28-year-old man with MNGIE syndrome with gastrointestinal dysmotility, inability to walk, leukoencephalopathy, ptosis, cachexia, and elevated serum thymidine. To halt progression of neurologic deficit, he first received a left-lobe partial liver transplantation. Although his motor deficit improved, gastrointestinal dysmotility persisted, requiring total parenteral nutrition. After exhaustive intestinal rehabilitation, he was listed for intestine transplantation. Two-and-half years after liver transplantation, he received an intestine transplant. At 4 years after LT and 20 months after the intestine transplant, he remains off parenteral nutrition and is slowly gaining weight. CONCLUSIONS This is the first reported case of mitochondrial neurogastrointestinal encephalomyopathy to undergo successful sequential liver and intestine transplantation.
Topics: Male; Humans; Adult; Cachexia; Retrospective Studies; Mitochondrial Encephalomyopathies; Ophthalmoplegia; Intestines; Leukoencephalopathies; Liver; Intestinal Pseudo-Obstruction; Muscular Dystrophy, Oculopharyngeal
PubMed: 38409779
DOI: 10.12659/AOT.941881 -
Cell Reports. Medicine Mar 2024Selenoprotein N (SEPN1) is a protein of the endoplasmic reticulum (ER) whose inherited defects originate SEPN1-related myopathy (SEPN1-RM). Here, we identify an...
Selenoprotein N (SEPN1) is a protein of the endoplasmic reticulum (ER) whose inherited defects originate SEPN1-related myopathy (SEPN1-RM). Here, we identify an interaction between SEPN1 and the ER-stress-induced oxidoreductase ERO1A. SEPN1 and ERO1A, both enriched in mitochondria-associated membranes (MAMs), are involved in the redox regulation of proteins. ERO1A depletion in SEPN1 knockout cells restores ER redox, re-equilibrates short-range MAMs, and rescues mitochondrial bioenergetics. ERO1A knockout in a mouse background of SEPN1 loss blunts ER stress and improves multiple MAM functions, including Ca levels and bioenergetics, thus reversing diaphragmatic weakness. The treatment of SEPN1 knockout mice with the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) mirrors the results of ERO1A loss. Importantly, muscle biopsies from patients with SEPN1-RM exhibit ERO1A overexpression, and TUDCA-treated SEPN1-RM patient-derived primary myoblasts show improvement in bioenergetics. These findings point to ERO1A as a biomarker and a viable target for intervention and to TUDCA as a pharmacological treatment for SEPN1-RM.
Topics: Humans; Mice; Animals; Muscle Proteins; Muscular Diseases; Taurochenodeoxycholic Acid; Oxidoreductases; Mice, Knockout
PubMed: 38402623
DOI: 10.1016/j.xcrm.2024.101439 -
International Journal of Molecular... Feb 2024Alcohol misuse and HIV independently induce myopathy. We previously showed that chronic binge alcohol (CBA) administration, with or without simian immunodeficiency virus...
Alcohol misuse and HIV independently induce myopathy. We previously showed that chronic binge alcohol (CBA) administration, with or without simian immunodeficiency virus (SIV), decreases differentiation capacity of male rhesus macaque myoblasts. We hypothesized that short-term alcohol and CBA/SIV would synergistically decrease differentiation capacity and impair bioenergetic parameters in female macaque myoblasts. Myoblasts from naïve (CBA/SIV), vehicle [VEH]/SIV, and CBA/SIV (N = 4-6/group) groups were proliferated (3 days) and differentiated (5 days) with 0 or 50 mM ethanol (short-term). CBA/SIV decreased differentiation and increased non-mitochondrial oxygen consumption rate (OCR) versus naïve and/or VEH/SIV. Short-term alcohol decreased differentiation; increased maximal and non-mitochondrial OCR, mitochondrial reactive oxygen species (ROS) production, and aldolase activity; and decreased glycolytic measures, ATP production, mitochondrial membrane potential (ΔΨm), and pyruvate kinase activity. Mitochondrial ROS production was closely associated with mitochondrial network volume, and differentiation indices were closely associated with key bioenergetic health and function parameters. Results indicate that short-term alcohol and CBA non-synergistically decrease myoblast differentiation capacity. Short-term alcohol impaired myoblast glycolytic function, driving the bioenergetic deficit. Results suggest potentially differing mechanisms underlying decreased differentiation capacity with short-term alcohol and CBA, highlighting the need to elucidate the impact of different alcohol use patterns on myopathy.
Topics: Female; Animals; Male; Simian Immunodeficiency Virus; Macaca mulatta; Simian Acquired Immunodeficiency Syndrome; Reactive Oxygen Species; Binge Drinking; Ethanol; Myoblasts; Energy Metabolism; Muscular Diseases; Viral Load
PubMed: 38397125
DOI: 10.3390/ijms25042448 -
International Journal of Molecular... Feb 2024Nicotinamide adenine dinucleotide (NAD) is a cofactor in redox reactions and an essential mediator of energy metabolism. The redox balance between NAD and NADH affects...
Nicotinamide adenine dinucleotide (NAD) is a cofactor in redox reactions and an essential mediator of energy metabolism. The redox balance between NAD and NADH affects various diseases, cell differentiation, and aging, and in recent years there has been a growing need for measurement techniques with improved accuracy. However, NAD(H) measurements, representing both NAD and NADH, have been limited by the compound's properties. We achieved highly sensitive simultaneous measurement of NAD and NADH under non-ion pairing, mobile phase conditions of water, or methanol containing 5 mM ammonium acetate. These were achieved using a simple pre-treatment and 7-min analysis time. Use of the stable isotope C-NAD as an internal standard enabled validation close to BMV criteria and demonstrated the robustness of NAD(H) determination. Measurements using this method showed that brain NAD(H) levels correlate strongly with plasma NAD(H) levels in the same mouse, indicating that NAD(H) concentrations in brain tissue are reflected in plasma. As NAD(H) is involved in various neurodegenerative diseases and cerebral ischemia, as well as brain diseases such as mitochondrial myopathies, monitoring changes in NADH levels in plasma after drug administration will be useful for development of future diagnostics and therapeutics.
Topics: Mice; Animals; NAD; Chromatography, Liquid; Liquid Chromatography-Mass Spectrometry; Tandem Mass Spectrometry; Brain Diseases; Brain; Oxidation-Reduction
PubMed: 38397001
DOI: 10.3390/ijms25042325 -
American Journal of Veterinary Research Apr 2024The aim of this study was to investigate the roles of ribonucleotide reductase subunit M2 (RRM2; subunit of ribonucleotide reductase) in severe woody breast (WB) and...
OBJECTIVE
The aim of this study was to investigate the roles of ribonucleotide reductase subunit M2 (RRM2; subunit of ribonucleotide reductase) in severe woody breast (WB) and normal breast muscles.
ANIMALS
40 8-week-old male Ross-708 broiler chickens.
METHODS
Quantitative PCR was performed to determine gene expression, and commercial ELISA/assay kits were used to obtain several enzymatic activities.
RESULTS
Results showed that RRM2 activity (P = .0002) and RRM2 (P = .05) and hydroxymethylbilane synthase expression (impaired oxygen transport and metabolism, P = .002) were reduced in WB, while caveolin-3 (defected membrane integrity, P = .09), endoglin (increased fibrosis, P = .06), and secreted protein acidic rich in cysteine (metabolic dysregulation, P = .09) expression tended to increase in WB. WB tended to have increased levels of homocysteine (P = .06), aspartate aminotransferase mitochondria (P = .02), pyruvate kinase (P = .04), DNA damage (P = .06), creatine kinase (P = .05), and triglyceride (P = .002) but decreased ATPase activity (P = .01), all indicating mitochondria dysfunction and tissue damage.
CLINICAL RELEVANCE
In this study, differences in various enzyme activities and increased DNA damage suggest that RRM2-mediated mitochondrial abnormalities may play a role in WB myopathy.
Topics: Animals; Male; Chickens; DNA Damage; Mitochondrial Diseases
PubMed: 38382194
DOI: 10.2460/ajvr.23.12.0283 -
Cureus Jan 2024Pathogenic variants in mitochondrial calcium uptake 1 ( manifest phenotypically heterogeneously but most frequently in the brain and skeletal muscle. Dolichocephaly,...
Pathogenic variants in mitochondrial calcium uptake 1 ( manifest phenotypically heterogeneously but most frequently in the brain and skeletal muscle. Dolichocephaly, arachnodactyly, diplopia, and distal myopathy have not been reported in carriers of a pathogenic variant. The patient is a 23-year-old female with consanguineous parents (first cousins) who was a carrier of the homozygous variant c.553C>T, phenotypically presenting with developmental delay, intellectual disability, ataxia, dysmorphia (dolichocephaly, arachnodactyly, clinodactyly, hypertelorism, wide nasal bridge), myopathy (ptosis, double vision, strabismus, distal limb weakness, diffuse wasting, hypotonia), hyperextensible joints and hyperkyphosis. Features not previously described were dolichocephaly, arachnodactyly, broad nasal bridge, double vision, and distal myopathy. She was treated with physical therapy, speech therapy, and occupational therapy and received escitalopram and mirtazapine for concomitant depression, anxiety disorder, and insomnia. The presented case shows that the phenotypic heterogeneity of pathogenic variants is even greater than previously assumed. Treatment of -related phenotypes is symptomatic, but these patients benefit from physical therapy, behavioral therapy, speech therapy, and antidepressant treatment.
PubMed: 38380193
DOI: 10.7759/cureus.52672