RESUMO
Over-expression of phosphoprotein enriched in diabetes/phosphoprotein enriched in astrocytes (PED/PEA-15) causes insulin resistance by interacting with the D4 domain of phospholipase D1 (PLD1). Indeed, the disruption of this association restores insulin sensitivity in cultured cells over-expressing PED/PEA-15. Whether the displacement of PLD1 from PED/PEA-15 improves insulin sensitivity in vivo has not been explored yet. In this work we show that treatment with a recombinant adenoviral vector containing the human D4 cDNA (Ad-D4) restores normal glucose homeostasis in transgenic mice overexpressing PED/PEA-15 (Tg ped/pea-15) by improving both insulin sensitivity and secretion. In skeletal muscle of these mice, D4 over-expression inhibited PED/PEA-15-PLD1 interaction, decreased Protein Kinase C alpha activation and restored insulin induced Protein Kinase C zeta activation, leading to amelioration of insulin-dependent glucose uptake. Interestingly, Ad-D4 administration improved insulin sensitivity also in high-fat diet treated obese C57Bl/6 mice. We conclude that PED/PEA-15-PLD1 interaction may represent a novel target for interventions aiming at improving glucose tolerance.
Assuntos
Terapia Genética , Resistência à Insulina/genética , Insulina/metabolismo , Obesidade/metabolismo , Fosfolipase D/genética , Fosfoproteínas/genética , Adenoviridae/genética , Animais , Proteínas Reguladoras de Apoptose , Dieta Hiperlipídica/efeitos adversos , Regulação da Expressão Gênica , Vetores Genéticos , Glucose/metabolismo , Humanos , Secreção de Insulina , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Obesidade/etiologia , Obesidade/genética , Obesidade/terapia , Fosfolipase D/metabolismo , Fosfoproteínas/metabolismo , Ligação Proteica , Proteína Quinase C/genética , Proteína Quinase C/metabolismo , Proteína Quinase C-alfa/genética , Proteína Quinase C-alfa/metabolismo , Estrutura Terciária de Proteína , Transdução de Sinais , TransgenesRESUMO
Obesity is a consequence of imbalance of food intake and energy expenditure that results in storage of energy as fat, primarily in adipose tissue. MicroRNAs are non-coding RNAs that regulate gene expression in metabolic pathways and they are also involved in fat-cell development. The aim of this study was to evaluate whether microRNA dysfunction contributes to obesity. We analyzed, by microarray, the expression profile of 1,458 microRNAs in subcutaneous adipose tissue (SAT) from nondiabetic severely obese (n = 20) and nonobese adults (n = 8). Among 42 differently expressed microRNAs, we confirmed by reverse-transcription PCR (RT-PCR) that miR-519d was overexpressed whereas the protein levels of peroxisome proliferator-activated receptor-α (PPARA) (a predicted miR 519d target) were lower, at western analysis, in severely obese vs. nonobese subjects. We also show that miR-519d specifically and dose-dependently suppressed translation of the PPARA protein, and increased lipid accumulation during preadipocyte differentiation. Because PPARA plays a central role in fatty acid homeostasis, and in the transcriptional regulation of genes that are necessary for maintenance of the redox balance during the oxidative catabolism of fatty acids, we suggest that PPARA loss and miR-519d overexpression could be associated with metabolic imbalance and subsequent adipocyte hypertrophy in SAT during obesity.