| Texto completo | |
| Autor(es): Mostrar menos - |
Goncalves, Dawit A. P.
;
Lira, Eduardo C.
;
Baviera, Amanda M.
;
Cao, Peirang
;
Zanon, Neusa M.
;
Arany, Zoltan
;
Bedard, Nathalie
;
Tanksale, Preeti
;
Wing, Simon S.
;
Lecker, Stewart H.
;
Kettelhut, Isis C.
;
Navegantes, Luiz C. C.
Número total de Autores: 12
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Endocrinology; v. 150, n. 12, p. 10-pg., 2009-12-01. |
| Resumo | |
Although it is well known that catecholamines inhibit skeletal muscle protein degradation, the molecular underlying mechanism remains unclear. This study was undertaken to investigate the role of beta(2)-adrenoceptors (AR) and cAMP in regulating the ubiquitin-proteasome system (UPS) in skeletal muscle. We report that increased levels of cAMP in isolated muscles, promoted by the cAMP phosphodiesterase inhibitor isobutyl methylxanthine was accompanied by decreased activity of the UPS, levels of ubiquitin-protein conjugates, and expression of atrogin-1, a key ubiquitin-protein ligase involved in muscle atrophy. In cultured myotubes, atrogin-1 induction after dexamethasone treatment was completely prevented by isobutyl methylxanthine. Furthermore, administration of clenbuterol, a selective beta(2)-agonist, to mice increased muscle cAMP levels and suppressed the fasting-induced expression of atrogin-1 and MuRF-1, atrogin-1 mRNA being much more responsive to clenbuterol. Moreover, clenbuterol increased the phosphorylation of muscle Akt and Foxo3a in fasted rats. Similar responses were observed in muscles exposed to dibutyryl-cAMP. The stimulatory effect of clenbuterol on cAMP and Akt was abolished in muscles from beta(2)-AR knockout mice. The suppressive effect of beta(2)-agonist on atrogin-1 was not mediated by PGC-1 alpha (peroxisome proliferator-activated receptor-gamma coactivator 1 alpha known to be induced by beta(2)-agonists and previously shown to inhibit atrogin-1 expression), because food-deprived PGC-1 alpha knockout mice were still sensitive to clenbuterol. These findings suggest that the cAMP increase induced by stimulation of beta(2)-AR in skeletal muscles from fasted mice is possibly the mechanism by which catecholamines suppress atrogin-1 and the UPS, this effect being mediated via phosphorylation of Akt and thus inactivation of Foxo3. (Endocrinology 150: 5395-5404, 2009) (AU) | |
| Processo FAPESP: | 06/06974-3 - Controle hormonal do metabolismo de proteinas em musculo esqueletico: papel da via pi3k/akt na regulacao da proteolise muscular pela insulina e catecolaminas. |
| Beneficiário: | Isis Do Carmo Kettelhut |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 04/02674-0 - Controle da perda de proteínas musculares em situações catabólicas: um estudo de microdiálise |
| Beneficiário: | Luiz Carlos Carvalho Navegantes |
| Modalidade de apoio: | Auxílio à Pesquisa - Jovens Pesquisadores |
| Processo FAPESP: | 09/07584-2 - Papel das vias de sinalização da Akt/Foxo e MEK/ERK no efeito antiatrófico mediado pelos adrenoceptores B2 em músculo esquelético de roedores |
| Beneficiário: | Dawit Albieiro Pinheiro Gonçalves |
| Modalidade de apoio: | Bolsas no Brasil - Doutorado |
| Processo FAPESP: | 08/06694-6 - Controle neural do metabolismo de proteínas |
| Beneficiário: | Isis Do Carmo Kettelhut |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |