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The G protein coupled receptor kinase 2 plays an essential role in beta-adrenergic receptor-induced insulin resistance.

Abstract：

AIMS:Insulin (Ins) resistance (IRES) associates to increased cardiovascular risk as observed in metabolic syndrome. Chronic stimulation of beta-adrenergic receptors (betaAR) due to exaggerated sympathetic nervous system activity is involved in the pathogenesis of IRES. The cellular levels of G protein coupled receptor kinase 2 (GRK2) increase during chronic betaAR stimulation, leading to betaAR desensitization. We tested the hypothesis that GRK2 plays a role in betaAR-induced IRES. METHODS AND RESULTS:We evaluated Ins-induced glucose uptake and signalling responses in vitro in cell overexpressing the beta(2)AR, the GRK2, or the catalytically dead mutant GRK2-DN. In a model of increased adrenergic activity, IRES and elevated cellular GRK2 levels, the spontaneously hypertensive rats (SHR) we performed the intravenous glucose tolerance test load. To inhibit GRK2, we synthesized a peptide based on the catalytical sequence of GRK2 conjugated with the antennapedia internalization sequence (Ant-124). Ins in human kidney embryonic (HEK-293) cells causes rapid accumulation of GRK2, tyrosine phosphorylation of Ins receptor substrate 1 (IRS1) and induces glucose uptake. In the same cell type, transgenic beta(2)AR overexpression causes GRK2 accumulation associated with significant deficit of IRS1 activation and glucose uptake by Ins. Similarly, transgenic GRK2 overexpression prevents Ins-induced tyrosine phosphorylation of IRS1 and glucose uptake, whereas GRK2-DN ameliorates glucose extraction. By immunoprecipitation, GRK2 binds IRS1 but not the Ins receptor in an Ins-dependent fashion, which is lost in HEK-GRK2 cells. Ant-124 improves Ins-induced glucose uptake in HEK-293 and HEK-GRK2 cells, but does not prevent GRK2/IRS1 interaction. In SHR, Ant-124 infusion for 30 days ameliorates IRES and IRS1 tyrosine phosphorylation. CONCLUSION:Our results suggest that GRK2 mediates adrenergic IRES and that inhibition of GRK2 activity leads to increased Ins sensitivity both in cells and in animal model of IRES.

journal_name

Cardiovasc Res

journal_title

Cardiovascular research

authors

Cipolletta E,Campanile A,Santulli G,Sanzari E,Leosco D,Campiglia P,Trimarco B,Iaccarino G

doi

10.1093/cvr/cvp252

subject

Has Abstract

pub_date

2009-12-01 00:00:00

pages

407-15

issue

eissn

0008-6363

issn

1755-3245

pii

cvp252

journal_volume

pub_type

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The G protein coupled receptor kinase 2 plays an essential role in beta-adrenergic receptor-induced insulin resistance.