Endothelin-1 suppresses insulin-stimulated Akt phosphorylation and glucose uptake via GPCR kinase 2 in skeletal muscle cells.

Autor: Horinouchi T; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Hoshi A; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Harada T; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Higa T; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Karki S; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Terada K; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Higashi T; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Mai Y; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Nepal P; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Mazaki Y; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan., Miwa S; Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo City, Japan.
Jazyk: angličtina
Zdroj: British journal of pharmacology [Br J Pharmacol] 2016 Mar; Vol. 173 (6), pp. 1018-32. Date of Electronic Publication: 2016 Feb 15.
DOI: 10.1111/bph.13406
Abstrakt: Background and Purpose: Endothelin-1 (ET-1) reduces insulin-stimulated glucose uptake in skeletal muscle, inducing insulin resistance. Here, we have determined the molecular mechanisms underlying negative regulation by ET-1 of insulin signalling.
Experimental Approach: We used the rat L6 skeletal muscle cells fully differentiated into myotubes. Changes in the phosphorylation of Akt was assessed by Western blotting. Effects of ET-1 on insulin-stimulated glucose uptake was assessed with [(3) H]-2-deoxy-d-glucose ([(3) H]2-DG). The C-terminus region of GPCR kinase 2 (GRK2-ct), a dominant negative GRK2, was overexpressed in L6 cells using adenovirus-mediated gene transfer. GRK2 expression was suppressed by transfection of the corresponding short-interfering RNA (siRNA).
Key Results: In L6 myotubes, insulin elicited sustained Akt phosphorylation at Thr(308) and Ser(473) , which was suppressed by ET-1. The inhibitory effects of ET-1 were prevented by treatment with a selective ETA receptor antagonist and a Gq protein inhibitor, overexpression of GRK2-ct and knockdown of GRK2. Insulin increased [(3) H]2-DG uptake rate in a concentration-dependent manner. ET-1 noncompetitively antagonized insulin-stimulated [(3) H]2-DG uptake. Blockade of ETA receptors, overexpression of GRK2-ct and knockdown of GRK2 prevented the ET-1-induced suppression of insulin-stimulated [(3) H]2-DG uptake. In L6 myotubes overexpressing FLAG-tagged GRK2, ET-1 facilitated the interaction of endogenous Akt with FLAG-GRK2.
Conclusions and Implications: Activation of ETA receptors with ET-1 suppressed insulin-induced Akt phosphorylation at Thr(308) and Ser(473) and [(3) H]2-DG uptake in a GRK2-dependent manner in skeletal muscle cells. These findings suggest that ETA receptors and GRK2 are potential targets for overcoming insulin resistance.
(© 2015 The British Pharmacological Society.)
Databáze: MEDLINE
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