RESUMO
At present there is no satisfactory treatment for McArdle's disease, deficiency of myophosphorylase. Injection of modified adenovirus 5 (AdV5) and adeno-associated virus 2 (AAV2) vectors containing myophosphorylase expression cassettes, into semitendinosus muscle of sheep with McArdle's disease, produced expression of functional myophosphorylase and some re-expression of the non-muscle glycogen phosphorylase isoforms (both liver and brain) in regenerating fibres. Expression of both non-muscle isoforms was also seen after control injections of AdV5LacZ vectors. There was up to an order of magnitude greater expression of phosphorylase after myophosphorylase vector injection than after LacZ controls (62% of sections with over 1000 positive muscle fibres, versus 7%). The results presented here suggest that the use of viral vector-mediated phosphorylase gene transfer may be applicable to the treatment of McArdle's disease and that sustained re-expression of the brain and liver isoforms should also be investigated as a possible treatment.
Assuntos
Técnicas de Transferência de Genes , Terapia Genética/métodos , Glicogênio Fosforilase Muscular/genética , Doença de Depósito de Glicogênio Tipo V/terapia , Músculo Esquelético/fisiologia , Adenoviridae/genética , Animais , Biópsia , DNA Complementar/genética , DNA Complementar/farmacologia , Modelos Animais de Doenças , Regulação Enzimológica da Expressão Gênica , Glicogênio Fosforilase Muscular/metabolismo , Doença de Depósito de Glicogênio Tipo V/genética , Doença de Depósito de Glicogênio Tipo V/patologia , Humanos , Óperon Lac , Fibras Musculares Esqueléticas/enzimologia , Fibras Musculares Esqueléticas/patologia , Músculo Esquelético/patologia , Reação do Ácido Periódico de Schiff , Ovinos , beta-Galactosidase/genéticaRESUMO
McArdle disease is due to an absence of the enzyme muscle glycogen phosphorylase and results in significant physical impairment in humans. We hypothesised that sodium valproate, an HDAC inhibitor, might have the ability to up-regulate the enzyme. We treated McArdle sheep with sodium valproate given enterically at 20-60 mg/kg body wt. Compared with untreated control animals, there was increased expression of phosphorylase in muscle fibres. The response was dose dependent and reached a maximum 2 hours after the application and increased with repeated applications. Improvement in mobility could not be demonstrated. These findings suggest that sodium valproate is a potential therapeutic treatment for McArdle disease.
Assuntos
Inibidores Enzimáticos/uso terapêutico , Doença de Depósito de Glicogênio Tipo V/tratamento farmacológico , Ácido Valproico/uso terapêutico , Animais , Aspartato Aminotransferases/sangue , Cálcio/sangue , Creatina Quinase/sangue , Modelos Animais de Doenças , Esquema de Medicação , Doença de Depósito de Glicogênio Tipo V/genética , Doença de Depósito de Glicogênio Tipo V/patologia , Doença de Depósito de Glicogênio Tipo V/veterinária , Ácido Láctico/metabolismo , Locomoção/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/enzimologia , Fosforilases/metabolismo , Ovinos , Fatores de TempoRESUMO
McArdle disease is caused by a deficiency of myophosphorylase and currently a satisfactory treatment is not available. The injection of notexin into, or the layering of notexin onto, the muscles of affected sheep resulted in necrosis followed by regeneration of muscle fibres with the expression of both non-muscle isoforms of phosphorylase within the fibres and a reduction of the amount of glycogen in the muscle with an increase in the strength of contraction and a decrease in fatiguability in the muscle fibres. The sustained re-expression of both the brain and liver isoforms of phosphorylase within the muscle fibres provides further emphasis that strategies to enhance the re-expression of these isoforms should be investigated as a possible treatment for McArdle disease.