TY - JOUR
T1 - The G protein coupled receptor kinase 2 plays an essential role in beta-adrenergic receptor-induced insulin resistance
AU - Cipolletta, Ersilia
AU - Campanile, Alfonso
AU - Santulli, Gaetano
AU - Sanzari, Emma
AU - Leosco, Dario
AU - Campiglia, Pietro
AU - Trimarco, Bruno
AU - Iaccarino, Guido
N1 - Funding Information:
This research was supported by a grant from the Agenzia Italiana del Farmaco (#FARM5STRH9) to B.T.; E.C. is supported by a fellowship from Dipartimento Farmaco Chimico, Università di Bari, progetto strategico PS_131, Regione Puglia.
PY - 2009
Y1 - 2009
N2 - AimsInsulin (Ins) resistance (IRES) associates to increased cardiovascular risk as observed in metabolic syndrome. Chronic stimulation of β-adrenergic receptors (βAR) 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 βAR stimulation, leading to βAR desensitization. We tested the hypothesis that GRK2 plays a role in βAR-induced IRES.Methods and resultsWe evaluated Ins-induced glucose uptake and signalling responses in vitro in cell overexpressing the β2AR, 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 β2AR 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. ConclusionOur 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.
AB - AimsInsulin (Ins) resistance (IRES) associates to increased cardiovascular risk as observed in metabolic syndrome. Chronic stimulation of β-adrenergic receptors (βAR) 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 βAR stimulation, leading to βAR desensitization. We tested the hypothesis that GRK2 plays a role in βAR-induced IRES.Methods and resultsWe evaluated Ins-induced glucose uptake and signalling responses in vitro in cell overexpressing the β2AR, 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 β2AR 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. ConclusionOur 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.
KW - Beta-adrenergic receptor
KW - Cardiovascular risk
KW - Desensitization
KW - G protein coupled receptor kinase
KW - Hypertension
KW - Insulin resistance
KW - Sympathetic nervous system
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U2 - 10.1093/cvr/cvp252
DO - 10.1093/cvr/cvp252
M3 - Article
C2 - 19620130
AN - SCOPUS:70450227198
SN - 0008-6363
VL - 84
SP - 407
EP - 415
JO - Cardiovascular research
JF - Cardiovascular research
IS - 3
ER -