Des-acyl ghrelin exhibits pro-anabolic and anti-catabolic effects on C2C12 myotubes exposed to cytokines and reduces burn-induced muscle proteolysis in rats

S Sheriff, N Kadeer, R Joshi, LA Friend… - Molecular and cellular …, 2012 - Elsevier
S Sheriff, N Kadeer, R Joshi, LA Friend, JH James, A Balasubramaniam
Molecular and cellular endocrinology, 2012Elsevier
Although ghrelin and GHRP-2 have been shown to inhibit skeletal muscle proteolysis in rats
with burn injury, the effects of des-acyl ghrelin (DAG) have not been reported. In this paper,
we demonstrate that continuous 24h administration of DAG attenuated burn-induced EDL
muscle proteolysis, and normalized elevated TNFα mRNA. Combined treatment of cultured
C2C12 myotubes with TNFα and IFN-γ (TNF+ IFN) inhibited protein synthesis and increased
protein breakdown; DAG abolished both effects. PI3 kinase inhibition by LY294002 and …
Although ghrelin and GHRP-2 have been shown to inhibit skeletal muscle proteolysis in rats with burn injury, the effects of des-acyl ghrelin (DAG) have not been reported. In this paper, we demonstrate that continuous 24h administration of DAG attenuated burn-induced EDL muscle proteolysis, and normalized elevated TNFα mRNA. Combined treatment of cultured C2C12 myotubes with TNFα and IFN-γ (TNF+IFN) inhibited protein synthesis and increased protein breakdown; DAG abolished both effects. PI3 kinase inhibition by LY294002 and mTOR inhibition by rapamycin blocked the reversal of the anti-anabolic effects of TNF+IFN-treated myotubes by DAG. DAG also reversed or attenuated the TNF+IFN-induced reduction in phosphorylation of Akt, FOXO1, 4E-BP-1, and GSK-3β in myotubes. Furthermore, DAG attenuated the atrophy signal, phospho-NF-κB, and the mRNA expression of MAFbx and MuRF1, upregulated by TNF+IFN in C2C12 myotubes. We conclude that DAG reduces muscle cachexia produced by injury and proinflammatory cytokines, and that DAG or DAG-based compounds may be useful in treating wasting disorders.
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