RESUMO
We previously reported that statin myopathy is associated with impaired carbohydrate (CHO) oxidation in fast-twitch rodent skeletal muscle, which we hypothesised occurred as a result of forkhead box protein O1 (FOXO1) mediated upregulation of pyruvate dehydrogenase kinase-4 (PDK4) gene transcription. Upregulation of FOXO gene targets known to regulate proteasomal and lysosomal muscle protein breakdown was also evident. We hypothesised that increasing CHO oxidation in vivo, using the pyruvate dehydrogenase complex (PDC) activator, dichloroacetate (DCA), would blunt activation of FOXO gene targets and reduce statin myopathy. Female Wistar Hanover rats were dosed daily for 12 days (oral gavage) with either vehicle (control, 0.5% w/v hydroxypropyl-methylcellulose 0.1% w/v polysorbate-80; n = 9), 88 mg( )kg(-1) day(-1) simvastatin (n = 8), 88 mg( )kg(-1) day(-1) simvastatin + 30 mg kg(-1) day(-1) DCA (n = 9) or 88 mg kg(-1) day(-1) simvastatin + 40 mg kg(-1) day(-1) DCA (n = 9). Compared with control, simvastatin reduced body mass gain and food intake, increased muscle fibre necrosis, plasma creatine kinase levels, muscle PDK4, muscle atrophy F-box (MAFbx) and cathepsin-L mRNA expression, increased PDK4 protein expression, and proteasome and cathepsin-L activity, and reduced muscle PDC activity. Simvastatin with DCA maintained body mass gain and food intake, abrogated the myopathy, decreased muscle PDK4 mRNA and protein, MAFbx and cathepsin-L mRNA, increased activity of PDC and reduced proteasome activity compared with simvastatin. PDC activation abolished statin myopathy in rodent skeletal muscle, which occurred at least in part via inhibition of FOXO-mediated transcription of genes regulating muscle CHO utilisation and protein breakdown.
Assuntos
Ácido Dicloroacético/farmacologia , Ativadores de Enzimas/farmacologia , Fatores de Transcrição Forkhead/metabolismo , Inibidores de Hidroximetilglutaril-CoA Redutases , Músculo Esquelético/efeitos dos fármacos , Doenças Musculares/prevenção & controle , Complexo Piruvato Desidrogenase/metabolismo , Sinvastatina , Acetilcarnitina/metabolismo , Animais , Peso Corporal/efeitos dos fármacos , Metabolismo dos Carboidratos/efeitos dos fármacos , Catepsina L/genética , Catepsina L/metabolismo , Citoproteção , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Ingestão de Alimentos/efeitos dos fármacos , Ativação Enzimática , Feminino , Fatores de Transcrição Forkhead/genética , Regulação da Expressão Gênica , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Músculo Esquelético/enzimologia , Músculo Esquelético/patologia , Doenças Musculares/induzido quimicamente , Doenças Musculares/enzimologia , Doenças Musculares/genética , Doenças Musculares/patologia , Necrose , Oxirredução , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Piruvato Desidrogenase Quinase de Transferência de Acetil , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Proteínas Ligases SKP Culina F-Box/genética , Proteínas Ligases SKP Culina F-Box/metabolismo , Fatores de TempoRESUMO
Transcript profiling ("Transcriptomics") is a widely used technique that obtains information on the abundance of multiple mRNA transcripts within a biological sample simultaneously. Therefore, when a number of such samples are analysed, as in a scientific experiment, large and complex data sets are gene-rated. Here, we describe the use of one method commonly used to generate transcriptomics data, namely the use of Affymetrix GeneChip microarrays. Data generated in transcriptomics experiments can be analysed using a multitude of approaches, but a common goal is to identify those transcripts whose abundance is altered by the experimental conditions, or which differ between sets of samples. Here, we describe a simple approach, the calculation of the volcano score, which identifies transcripts with altered abundance, taking into account both the magnitude of the alteration and its statistical significance.