Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.711
Filtrar
1.
Neurology ; 94(7): e687-e698, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-31896620

RESUMO

OBJECTIVE: To investigate the safety and efficacy of escalating doses of the semi-synthetic triterpenoid omaveloxolone in patients with mitochondrial myopathy. METHODS: In cohorts of 8-13, 53 participants were randomized double-blind to 12 weeks of treatment with omaveloxolone 5, 10, 20, 40, 80, or 160 mg, or placebo. Outcome measures were change in peak cycling exercise workload (primary), in 6-minute walk test (6MWT) distance (secondary), and in submaximal exercise heart rate and plasma lactate (exploratory). RESULTS: No differences in peak workload or 6MWT were observed at week 12 with omaveloxolone treatment vs placebo for all omaveloxolone dose groups. In contrast, omaveloxolone 160 mg reduced heart rate at week 12 by 12.0 ± 4.6 bpm (SE) during submaximal exercise vs placebo, p = 0.01, and by 8.7 ± 3.5 bpm (SE) vs baseline, p = 0.02. Similarly, blood lactate was 1.4 ± 0.7 mM (SE) lower vs placebo, p = 0.04, and 1.6 ± 0.5 mM (SE) lower vs baseline at week 12, p = 0.003, with omaveloxolone 160 mg treatment. Adverse events were generally mild and infrequent. CONCLUSIONS: Omaveloxolone 160 mg was well-tolerated, and did not lead to change in the primary outcome measure, but improved exploratory endpoints lowering heart rate and lactate production during submaximal exercise, consistent with improved mitochondrial function and submaximal exercise tolerance. Therefore, omaveloxolone potentially benefits patients with mitochondrial myopathy, which encourages further investigations of omaveloxolone in this patient group. CLINICALTRIALSGOV IDENTIFIER: NCT02255422. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that, for patients with mitochondrial myopathy, omaveloxolone compared to placebo did not significantly change peak exercise workload.


Assuntos
Anti-Inflamatórios/uso terapêutico , Miopatias Mitocondriais/tratamento farmacológico , Triterpenos/uso terapêutico , Adulto , Anti-Inflamatórios/efeitos adversos , Biomarcadores/sangue , Relação Dose-Resposta a Droga , Método Duplo-Cego , Exercício Físico , Teste de Esforço , Feminino , Frequência Cardíaca/efeitos dos fármacos , Humanos , Ácido Láctico/sangue , Masculino , Pessoa de Meia-Idade , Miopatias Mitocondriais/fisiopatologia , Fator 2 Relacionado a NF-E2/metabolismo , Resultado do Tratamento , Triterpenos/efeitos adversos
2.
Muscle Nerve ; 61(1): 81-87, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31588577

RESUMO

INTRODUCTION: Myopathy associated with anti-mitochondrial antibody (AMA) has recently been characterized as a distinct type of idiopathic inflammatory myopathy. The purpose of this study is to evaluate the pattern of involvement in thigh muscles in AMA myopathy using MRI. METHODS: Six patients with AMA myopathy were identified and their muscle MRI findings evaluated. RESULTS: On thigh muscle MRI, all six patients showed high signal intensity with short-tau inversion recovery that reflected disease activity mostly in the adductor magnus, called a "cuneiform sign." Fatty degeneration was also prominent in the adductor magnus, as well as the semimembranosus muscles. DISCUSSION: These characteristic changes on MRI contrast with those of other inflammatory myopathies. From these observations, we concluded that the localization pattern of the inflammatory changes in muscle MRI can contribute to the diagnosis of AMA myopathy.


Assuntos
Autoanticorpos/imunologia , Doenças Autoimunes/complicações , Doenças Autoimunes/diagnóstico por imagem , Mitocôndrias Musculares/imunologia , Miopatias Mitocondriais/diagnóstico por imagem , Miopatias Mitocondriais/etiologia , Músculo Esquelético/diagnóstico por imagem , Coxa da Perna/diagnóstico por imagem , Tecido Adiposo/patologia , Adulto , Idoso , Atrofia , Feminino , Granuloma/patologia , Humanos , Hipertrofia , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/patologia , Coxa da Perna/patologia
3.
Neurology ; 93(18): e1720-e1731, 2019 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-31570565

RESUMO

OBJECTIVE: To investigate the effectiveness of Energetic, a self-management group program combining aerobic training, energy conservation management, and relapse prevention to improve social participation in patients with neuromuscular disease (NMD) and chronic fatigue. METHODS: In this multicenter, assessor-blinded, 2-armed randomized controlled trial with repeated measurements, 53 patients with various types of NMD and chronic fatigue were randomly allocated to Energetic, a 4-month group intervention, or to usual care. The primary endpoint was social participation assessed with the Canadian Occupational Performance Measure (COPM) performance scale immediately postintervention. Secondary outcomes included COPM satisfaction scale, 6-Minute Walk Test (6MWT), and Checklist Individual Strength-subscale fatigue. Participants were followed for 11 months postintervention. Data were analyzed with linear models that account for repeated measurements. RESULTS: Directly after intervention, the mean group difference for COPM-performance was 1.7 (95% confidence interval [CI] 1.0-2.4; p < 0.0001) in favor of the intervention group (n = 29), adjusted for baseline, sex, diagnosis, and work status. This effect was retained at 11 months follow-up (0.9; 95% CI 0.0-1.7; p = 0.049). The COPM satisfaction scale and 6MWT improved more in the intervention group compared to usual care. After 3 and 11 months follow-up, most beneficial effects on social participation and functional endurance were retained. CONCLUSION: Energetic led to sustainable improvements in social participation and functional endurance compared to usual care in patients with NMD and chronic fatigue.Clinicaltrials.gov IDENTIFIER: NCT02208687. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that a combination of aerobic training, energy conservation management, and relapse prevention improves social participation in patients with NMD and chronic fatigue.


Assuntos
Terapia por Exercício/métodos , Fadiga/reabilitação , Doenças Neuromusculares/reabilitação , Terapia Ocupacional/métodos , Autogestão/métodos , Participação Social , Adulto , Afeto , Ansiedade , Fadiga/fisiopatologia , Feminino , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Miopatias Mitocondriais/fisiopatologia , Miopatias Mitocondriais/reabilitação , Distrofia Muscular Facioescapuloumeral/fisiopatologia , Distrofia Muscular Facioescapuloumeral/reabilitação , Miastenia Gravis/fisiopatologia , Miastenia Gravis/reabilitação , Miosite de Corpos de Inclusão/fisiopatologia , Miosite de Corpos de Inclusão/reabilitação , Doenças Neuromusculares/fisiopatologia , Educação de Pacientes como Assunto , Resistência Física , Prevenção Secundária , Autoeficácia , Autogestão/educação , Método Simples-Cego , Teste de Caminhada
5.
Curr Opin Ophthalmol ; 30(6): 476-483, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31436541

RESUMO

PURPOSE OF REVIEW: Inherited myopathies, and in particular mitochondrial myopathies, are heterogeneous disorders, and ocular manifestations may be the presenting feature or offer important diagnostic clues. The ophthalmologist may be key to diagnosis, facilitating recognition of associated potentially life-threatening organ manifestations and an integral part of multidisciplinary care. This review, focusing especially on mitochondrial myopathies, provides updates on clinical features, diagnosis and recent therapeutic developments. RECENT FINDINGS: Ptosis and/or ophthalmoplegia is present in over half of patients with mitochondrial disease, and associated clinical features imply specific genetic associations. Advances in next-generation sequencing have led to rapid evolution in the field, improving diagnosis rates, facilitating identification of novel genes, mutations and phenotypes, and providing important insights into disease mechanisms and therapeutic possibilities. Improved understanding of molecular mechanisms in inherited myopathies is enabling the development of experimental molecular therapies with clinical potential. SUMMARY: Genetic advances are driving progress in the field of inherited myopathies, influencing diagnosis, understanding of disease and development of therapies. Recognition of key features can impact diagnosis and management of these important conditions.


Assuntos
Oftalmopatias Hereditárias/genética , Mitocôndrias Musculares/patologia , Miopatias Mitocondriais/genética , Músculos Oculomotores/patologia , Oftalmoplegia Externa Progressiva Crônica/genética , Oftalmopatias Hereditárias/diagnóstico , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Miopatias Mitocondriais/diagnóstico , Oftalmoplegia Externa Progressiva Crônica/diagnóstico
6.
Nat Commun ; 10(1): 2576, 2019 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-31189900

RESUMO

Mitochondrial quality control is essential in highly structured cells such as neurons and muscles. In skeletal muscle the mitochondrial fission proteins are reduced in different physiopathological conditions including ageing sarcopenia, cancer cachexia and chemotherapy-induced muscle wasting. However, whether mitochondrial fission is essential for muscle homeostasis is still unclear. Here we show that muscle-specific loss of the pro-fission dynamin related protein (DRP) 1 induces muscle wasting and weakness. Constitutive Drp1 ablation in muscles reduces growth and causes animal death while inducible deletion results in atrophy and degeneration. Drp1 deficient mitochondria are morphologically bigger and functionally abnormal. The dysfunctional mitochondria signals to the nucleus to induce the ubiquitin-proteasome system and an Unfolded Protein Response while the change of mitochondrial volume results in an increase of mitochondrial Ca2+ uptake and myofiber death. Our findings reveal that morphology of mitochondrial network is critical for several biological processes that control nuclear programs and Ca2+ handling.


Assuntos
Dinaminas/metabolismo , Mitocôndrias Musculares/patologia , Dinâmica Mitocondrial/fisiologia , Miopatias Mitocondriais/patologia , Músculo Esquelético/patologia , Animais , Cálcio/metabolismo , Núcleo Celular/metabolismo , Modelos Animais de Doenças , Dinaminas/genética , Homeostase/fisiologia , Humanos , Camundongos , Camundongos Knockout , Miopatias Mitocondriais/genética , Miopatias Mitocondriais/mortalidade , Músculo Esquelético/citologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteólise , Ubiquitinas/metabolismo , Resposta a Proteínas não Dobradas/fisiologia
7.
Orphanet J Rare Dis ; 14(1): 100, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-31060578

RESUMO

BACKGROUND: TK2 gene encodes for mitochondrial thymidine kinase, which phosphorylates the pyrimidine nucleosides thymidine and deoxycytidine. Recessive mutations in the TK2 gene are responsible for the 'myopathic form' of the mitochondrial depletion/multiple deletions syndrome, with a wide spectrum of severity. METHODS: We describe 18 patients with mitochondrial myopathy due to mutations in the TK2 gene with absence of clinical symptoms until the age of 12. RESULTS: The mean age of onset was 31 years. The first symptom was muscle limb weakness in 10/18, eyelid ptosis in 6/18, and respiratory insufficiency in 2/18. All patients developed variable muscle weakness during the evolution of the disease. Half of patients presented difficulty in swallowing. All patients showed evidence of respiratory muscle weakness, with need for non-invasive Mechanical Ventilation in 12/18. Four patients had deceased, all of them due to respiratory insufficiency. We identified common radiological features in muscle magnetic resonance, where the most severely affected muscles were the gluteus maximus, semitendinosus and sartorius. On muscle biopsies typical signs of mitochondrial dysfunction were associated with dystrophic changes. All mutations identified were previously reported, being the most frequent the in-frame deletion p.Lys202del. All cases showed multiple mtDNA deletions but mtDNA depletion was present only in two patients. CONCLUSIONS: The late-onset is the less frequent form of presentation of the TK2 deficiency and its natural history is not well known. Patients with late onset TK2 deficiency have a consistent and recognizable clinical phenotype and a poor prognosis, due to the high risk of early and progressive respiratory insufficiency.


Assuntos
Miopatias Mitocondriais/enzimologia , Timidina Quinase/deficiência , Adolescente , Adulto , Criança , DNA Mitocondrial/genética , Feminino , Humanos , Transtornos de Início Tardio/enzimologia , Transtornos de Início Tardio/metabolismo , Transtornos de Início Tardio/patologia , Masculino , Pessoa de Meia-Idade , Miopatias Mitocondriais/genética , Músculo Esquelético/enzimologia , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Doenças Musculares/enzimologia , Doenças Musculares/genética , Mutação/genética , Estudos Retrospectivos , Timidina Quinase/genética , Adulto Jovem
8.
Toxicon ; 166: 46-55, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31102596

RESUMO

'Go Slow myopathy' (GSM) is a suspected toxic myopathy in dogs that primarily occurs in the North Island of New Zealand, and affected dogs usually have a history of consuming meat, offal or bones from wild pigs (including previously frozen and/or cooked meat). Previous epidemiological and pathological studies on GSM have demonstrated that changes in mitochondrial structure and function are most likely caused by an environmental toxin that dogs are exposed to through the ingestion of wild pig. The disease has clinical, histological and biochemical similarities to poisoning in people and animals from the plant Ageratina altissima (white snakeroot). Aqueous and lipid extracts were prepared from liver samples of 24 clinically normal dogs and 15 dogs with GSM for untargeted liquid chromatography-mass spectrometry. Group-wise comparisons of mass spectral data revealed 38 features that were significantly different (FDR<0.05) between normal dogs and those with GSM in aqueous extracts, and 316 significantly different features in lipid extracts. No definitive cause of the myopathy was identified, but alkaloids derived from several plant species were among the possible identities of features that were more abundant in liver samples from affected dogs compared to normal dogs. Mass spectral data also revealed that dogs with GSM have reduced hepatic phospholipid and sphingolipid concentrations relative to normal dogs. In addition, affected dogs had changes in the abundance of kynurenic acid, various dicarboxylic acids and N-acetylated branch chain amino acids, suggestive of mitochondrial dysfunction.


Assuntos
Doenças do Cão/induzido quimicamente , Metaboloma , Miopatias Mitocondriais/veterinária , Intoxicação por Plantas/veterinária , Alcaloides/isolamento & purificação , Animais , Cromatografia Líquida/veterinária , Doenças do Cão/metabolismo , Cães , Fígado/metabolismo , Espectrometria de Massas/veterinária , Miopatias Mitocondriais/patologia , Nova Zelândia , Intoxicação por Plantas/diagnóstico
11.
Int J Rheum Dis ; 22(6): 1152-1156, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30968563

RESUMO

Mitochondrial diseases are a group of disorders presenting mainly during infancy due to pathological dysfunction of the mitochondrial respiratory chain. We report a case of mitochondrial disease in an elderly woman complaining of generalized myalgia. A 69-year-old woman was admitted due to fatigue, general weakness, and a drowsy mental status. A brain magnetic resonance imaging (MRI) demonstrated multifocal lesions of increased T2 signal intensity, and laboratory findings were consistent with Fanconi syndrome. During her hospital course, she developed seizures, stress-induced cardiomyopathy, and respiratory failure. A muscle biopsy demonstrated ragged-red fibers in the muscle tissues seen in mitochondrial myopathy. We confirmed an 8 kb deletion in her mitochondrial DNA. Following treatment with l-carnitine, coenzyme Q10, and supportive measures, brain lesions on MRI scans disappeared, and the general symptoms gradually improved.


Assuntos
Síndrome de Fanconi/diagnóstico , Miopatias Mitocondriais/diagnóstico , Vasculite Sistêmica/diagnóstico , Idade de Início , Idoso , Diagnóstico Diferencial , Síndrome de Fanconi/genética , Síndrome de Fanconi/terapia , Feminino , Humanos , Miopatias Mitocondriais/genética , Miopatias Mitocondriais/terapia , Valor Preditivo dos Testes , Prognóstico
13.
Neuropathology ; 39(2): 162-167, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30847961

RESUMO

Oral nucleoside analogs (NAs) reduce hepatitis B virus (HBV) replication by inhibiting HBV DNA polymerase. However, NAs can also affect human mitochondrial DNA (mtDNA) polymerase, which can lead to mtDNA depletion (quantitative abnormality). Indeed, several mitochondrial myopathy cases have been reported in which a reduced mtDNA copy number was induced by oral NAs for hepatitis B. Herein, we report a case of toxic myopathy with multiple mtDNA deletions (qualitative abnormality) associated with long-term use of NAs for hepatitis B. A 68-year-old woman, who underwent long-term treatment with lamivudine and adefovir for chronic hepatitis B, developed proximal muscle weakness in the four extremities. Neurological examination showed mild proximal muscle weakness and atrophy in the four extremities. Upon admission to our hospital, her blood lactate/pyruvate ratio during an aerobic exercise test was elevated. Myogenic patterns were observed in lower limb muscles on electromyographic examination. Muscle magnetic resonance imaging revealed diffuse atrophy of proximal muscles in the four extremities with no signal changes. A biopsy from the biceps brachii muscle showed an abnormally large variation in fiber size, scattered muscle fibers with decreased cytochrome c oxidase activity, and ragged-red fibers. Analysis of mtDNA from skeletal muscle revealed no decrease in copy number but increased incidence of multiple deletions, including a deletion of 4977 base pairs (known as the common deletion) reflecting oxidative stress-induced mtDNA damage. This case study indicates that long-term oral antiviral therapy for hepatitis B can induce chronic oxidative damage to mtDNA resulting in qualitative mtDNA abnormalities and toxic myopathy.


Assuntos
Antivirais/efeitos adversos , Hepatite B Crônica/tratamento farmacológico , Miopatias Mitocondriais/induzido quimicamente , Miopatias Mitocondriais/patologia , Adenina/efeitos adversos , Adenina/análogos & derivados , Administração Oral , Idoso , DNA Mitocondrial , Feminino , Deleção de Genes , Hepatite B Crônica/complicações , Humanos , Lamivudina/efeitos adversos , Miopatias Mitocondriais/complicações , Miopatias Mitocondriais/genética , Músculo Esquelético/patologia , Organofosfonatos/efeitos adversos
14.
Dis Markers ; 2019: 2984747, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30881520

RESUMO

Because tandem mass spectrometry- (MS/MS-) based newborn screening identifies many suspicious cases of fatty acid oxidation and carnitine cycle disorders, a simple, noninvasive test is required to confirm the diagnosis. We have developed a novel method to evaluate the metabolic defects in peripheral blood mononuclear cells loaded with deuterium-labeled fatty acids directly using the ratios of acylcarnitines determined by flow injection MS/MS. We have identified diagnostic indices for the disorders as follows: decreased ratios of d27-C14-acylcarnitine/d31-C16-acylcarnitine and d23-C12-acylcarnitine/d31-C16-acylcarnitine for carnitine palmitoyltransferase-II (CPT-II) deficiency, decreased ratios of d23-C12-acylcarnitine/d27-C14-acylcarnitine for very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency, and increased ratios of d29-C16-OH-acylcarnitine/d31-C16-acylcarnitine for trifunctional protein (TFP) deficiency, together with increased ratios of d7-C4-acylcarnitine/d31-C16-acylcarnitine for carnitine palmitoyltransferase-I deficiency. The decreased ratios of d1-acetylcarnitine/d31-C16-acylcarnitine could be indicative of ß-oxidation ability in patients with CPT-II, VLCAD, and TFP deficiencies. Overall, our data showed that the present method was valuable for establishing a rapid diagnosis of fatty acid oxidation disorders and carnitine cycle disorders and for complementing gene analysis because our diagnostic indices may overcome the weaknesses of conventional enzyme activity measurements using fibroblasts or mononuclear cells with assumedly uncertain viability.


Assuntos
Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Cardiomiopatias/sangue , Ácidos Graxos/metabolismo , Erros Inatos do Metabolismo Lipídico/sangue , Espectrometria de Massas/métodos , Doenças Mitocondriais/sangue , Miopatias Mitocondriais/sangue , Proteína Mitocondrial Trifuncional/deficiência , Técnicas de Diagnóstico Molecular/métodos , Monócitos/química , Doenças Musculares/sangue , Doenças do Sistema Nervoso/sangue , Rabdomiólise/sangue , Acil-CoA Desidrogenase de Cadeia Longa/sangue , Adulto , Biomarcadores/sangue , Carnitina/análogos & derivados , Carnitina/química , Carnitina O-Palmitoiltransferase/deficiência , Deutério/química , Humanos , Lactente , Proteína Mitocondrial Trifuncional/sangue , Monócitos/metabolismo , Oxirredução
15.
Chin Med J (Engl) ; 132(7): 805-810, 2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30897595

RESUMO

BACKGROUND: Abnormally activated mechanistic target of rapamycin (mTOR) pathway has been reported in several model animals with inherited metabolic myopathies (IMMs). However, the profiles of mTOR pathway in skeletal muscles from patients are still unknown. This study aimed to analyze the activity of mTOR pathway in IMMs muscles. METHODS: We collected muscle samples from 25 patients with mitochondrial myopathy (MM), lipid storage disease (LSD) or Pompe disease (PD). To evaluate the activity of mTOR pathway in muscle specimens, phosphorylation of S6 ribosomal protein (p-S6) and p70S6 kinase (p-p70S6K) were analyzed by Western blotting and immunohistochemistry. RESULTS: Western blotting results showed that p-p70S6K/p70S6K in muscles from LSD and MM was up-regulated when compared with normal controls (NC) (NC vs. LSD, U = 2.000, P = 0.024; NC vs. MM: U = 6.000, P = 0.043). Likewise, p-S6/S6 was also up-regulated in muscles from all three subgroups of IMMs (NC vs. LSD, U = 0.000, P = 0.006; NC vs. PD, U = 0.000, P = 0.006; NC vs. MM, U = 1.000, P = 0.007). Immunohistochemical study revealed that p-S6 was mainly expressed in fibers with metabolic defect. In MM muscles, most p-S6 positive fibers showed cytochrome C oxidase (COX) deficiency (U = 5.000, P = 0.001). In LSD and PD muscles, p-S6 was mainly overexpressed in fibers with intramuscular vacuoles containing lipid droplets (U = 0.000, P = 0.002) or basophilic materials (U = 0.000, P = 0.002). CONCLUSION: The mTOR pathway might be activated in myofibers with various metabolic defects, which might provide evidence for mTOR inhibition therapy in human IMMs.


Assuntos
Doenças Musculares/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Adolescente , Adulto , Idoso , Western Blotting , Criança , Pré-Escolar , Feminino , Doença de Depósito de Glicogênio Tipo II/genética , Doença de Depósito de Glicogênio Tipo II/metabolismo , Humanos , Imuno-Histoquímica , Técnicas In Vitro , Erros Inatos do Metabolismo Lipídico/genética , Erros Inatos do Metabolismo Lipídico/metabolismo , Masculino , Pessoa de Meia-Idade , Miopatias Mitocondriais/genética , Miopatias Mitocondriais/metabolismo , Doenças Musculares/genética , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Adulto Jovem
18.
Skelet Muscle ; 9(1): 5, 2019 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-30791960

RESUMO

BACKGROUND: Group I Paks are serine/threonine kinases that function as major effectors of the small GTPases Rac1 and Cdc42, and they regulate cytoskeletal dynamics, cell polarity, and transcription. We previously demonstrated that Pak1 and Pak2 function redundantly to promote skeletal myoblast differentiation during postnatal development and regeneration in mice. However, the roles of Pak1 and Pak2 in adult muscle homeostasis are unknown. Choline kinase ß (Chk ß) is important for adult muscle homeostasis, as autosomal recessive mutations in CHKß are associated with two human muscle diseases, megaconial congenital muscular dystrophy and proximal myopathy with focal depletion of mitochondria. METHODS: We analyzed mice conditionally lacking Pak1 and Pak2 in the skeletal muscle lineage (double knockout (dKO) mice) over 1 year of age. Muscle integrity in dKO mice was assessed with histological stains, immunofluorescence, electron microscopy, and western blotting. Assays for mitochondrial respiratory complex function were performed, as was mass spectrometric quantification of products of choline kinase. Mice and cultured myoblasts deficient for choline kinase ß (Chk ß) were analyzed for Pak1/2 phosphorylation. RESULTS: dKO mice developed an age-related myopathy. By 10 months of age, dKO mouse muscles displayed centrally-nucleated myofibers, fibrosis, and signs of degeneration. Disease severity occurred in a rostrocaudal gradient, hindlimbs more strongly affected than forelimbs. A distinctive feature of this myopathy was elongated and branched intermyofibrillar (megaconial) mitochondria, accompanied by focal mitochondrial depletion in the central region of the fiber. dKO muscles showed reduced mitochondrial respiratory complex I and II activity. These phenotypes resemble those of rmd mice, which lack Chkß and are a model for human diseases associated with CHKß deficiency. Pak1/2 and Chkß activities were not interdependent in mouse skeletal muscle, suggesting a more complex relationship in regulation of mitochondria and muscle homeostasis. CONCLUSIONS: Conditional loss of Pak1 and Pak2 in mice resulted in an age-dependent myopathy with similarity to mice and humans with CHKß deficiency. Protein kinases are major regulators of most biological processes but few have been implicated in muscle maintenance or disease. Pak1/Pak2 dKO mice offer new insights into these processes.


Assuntos
Miopatias Mitocondriais/metabolismo , Músculo Esquelético/metabolismo , Quinases Ativadas por p21/metabolismo , Animais , Colina Quinase/metabolismo , Feminino , Masculino , Camundongos Knockout , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Miopatias Mitocondriais/genética , Miopatias Mitocondriais/patologia , Proteínas Mitocondriais/metabolismo , Músculo Esquelético/ultraestrutura , Quinases Ativadas por p21/genética
19.
Mol Cell Probes ; 44: 14-20, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30682426

RESUMO

The heterooctameric mitochondrial trifunctional protein (MTP), composed of four α- and ß-subunits harbours three enzymes that each perform a different function in mitochondrial fatty acid ß-oxidation. Pathogenic variants in the MTP genes (HADHA and HADHB) cause MTP deficiency, a rare autosomal recessive metabolic disorder characterized by phenotypic heterogeneity ranging from severe, early-onset, cardiac disease to milder, later-onset, myopathy and neuropathy. Since metabolic myopathies and neuropathies are a group of rare genetic disorders and their associated muscle symptoms may be subtle, the diagnosis is often delayed. Here we evaluated data of 161 patients with myopathy and 242 patients with neuropathy via next generation sequencing (NGS) and report the diagnostic yield in three patients of this cohort by the detection of disease-causing variants in the HADHA or HADHB gene. The mitigated phenotypes of this treatable disease were missed by the newborn screening, highlighting the importance of phenotype-based NGS analysis in patients with rare and clinically very variable disorders such as MTP deficiency.


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Subunidade alfa da Proteína Mitocondrial Trifuncional/genética , Subunidade beta da Proteína Mitocondrial Trifuncional/genética , Mutação/genética , Adolescente , Cardiomiopatias/genética , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Lactente , Erros Inatos do Metabolismo Lipídico/genética , Masculino , Miopatias Mitocondriais/genética , Proteína Mitocondrial Trifuncional/deficiência , Proteína Mitocondrial Trifuncional/genética , Doenças do Sistema Nervoso/genética , Fenótipo , Rabdomiólise/genética , Síndrome
20.
Biochim Biophys Acta Bioenerg ; 1860(1): 52-59, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30414414

RESUMO

Protons are transported from the mitochondrial matrix to the intermembrane space of mitochondria during the transfer of electrons to oxygen and shuttled back to the matrix by the a subunit and a ring of identical c subunits across the membrane domain (FO) of ATP synthase, which is coupled to ATP synthesis. A mutation (m.9176 T > G) of the mitochondrial ATP6 gene that replaces an universally conserved leucine residue into arginine at amino acid position 217 of human subunit a (aL217R) has been associated to NARP (Neuropathy, Ataxia and Retinitis Pigmentosa) and MILS (Maternally Inherited Leigh's Syndrome) diseases. We previously showed that an equivalent thereof in Saccharomyces cerevisiae (aL237R) severely impairs subunit a assembly/stability and decreases by >90% the rate of mitochondrial ATP synthesis. Herein we identified three spontaneous first-site intragenic suppressors (aR237M, aR237T and aR237S) that fully restore ATP synthase assembly. However, mitochondrial ATP synthesis rate was only partially recovered (40-50% vs wild type yeast). In light of recently described high-resolution yeast ATP synthase structures, the detrimental consequences of the aL237R change can be explained by steric and electrostatic hindrance with the universally conserved subunit a arginine residue (aR176) that is essential to FO activity. aL237 together with three other nearby hydrophobic residues have been proposed to prevent ion shortage between two physically separated hydrophilic pockets within the FO. Our results suggest that aL237 favors subunit c-ring rotation by optimizing electrostatic interaction between aR176 and an acidic residue in subunit c (cE59) known to be essential also to the activity of FO.


Assuntos
Trifosfato de Adenosina/biossíntese , Leucina/fisiologia , ATPases Mitocondriais Próton-Translocadoras/química , Mutação , Proteínas de Saccharomyces cerevisiae/genética , Sequência Conservada , Humanos , Doença de Leigh/etiologia , Miopatias Mitocondriais/etiologia , ATPases Mitocondriais Próton-Translocadoras/genética , Subunidades Proteicas , Retinite Pigmentosa/etiologia , Relação Estrutura-Atividade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA