RGD Reference Report - Endothelin-1 suppresses insulin-stimulated Akt phosphorylation and glucose uptake via GPCR kinase 2 in skeletal muscle cells. - Rat Genome Database

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

Authors: Horinouchi, Takahiro  Hoshi, Akimasa  Harada, Takuya  Higa, Tsunaki  Karki, Sarita  Terada, Koji  Higashi, Tsunehito  Mai, Yosuke  Nepal, Prabha  Mazaki, Yuichi  Miwa, Soichi 
Citation: Horinouchi T, etal., Br J Pharmacol. 2016 Mar;173(6):1018-32. doi: 10.1111/bph.13406. Epub 2016 Feb 15.
RGD ID: 13514041
Pubmed: (View Article at PubMed) PMID:26660861
DOI: Full-text: DOI:10.1111/bph.13406


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.

Annotation

Gene Ontology Annotations    

Objects Annotated

Genes (Rattus norvegicus)
Grk2  (G protein-coupled receptor kinase 2)


Additional Information