Selective Enhancement of Insulin Sensitivity in the Endothelium in Vivo Reveals a Novel Proatherosclerotic Signaling Loop

TY - JOUR

T1 - Selective Enhancement of Insulin Sensitivity in the Endothelium in Vivo Reveals a Novel Proatherosclerotic Signaling Loop

AU - Viswambharan, Hema

AU - Yuldasheva, Nadira Y.

AU - Sengupta, Anshuman

AU - Imrie, Helen

AU - Gage, Matthew C.

AU - Haywood, Natalie

AU - Walker, Andrew M N

AU - Skromna, Anna

AU - Makova, Natallia

AU - Galloway, Stacey

AU - Shah, Pooja

AU - Sukumar, Piruthivi

AU - Porter, Karen E.

AU - Grant, Peter J.

AU - Shah, Ajay

AU - Santos, Celio X.

AU - Li, Jing

AU - Beech, David J.

AU - Wheatcroft, Stephen B.

AU - Cubbon, Richard M.

AU - Kearney, Mark T.

PY - 2017/3/3

Y1 - 2017/3/3

N2 - Rationale: In the endothelium, insulin stimulates endothelial NO synthase (eNOS) to generate the antiatherosclerotic signaling radical NO. Insulin-resistant type 2 diabetes mellitus is associated with reduced NO availability and accelerated atherosclerosis. The effect of enhancing endothelial insulin sensitivity on NO availability is unclear. Objective: To answer this question, we generated a mouse with endothelial cell (EC)-specific overexpression of the human insulin receptor (hIRECO) using the Tie2 promoter-enhancer. Methods and Results: hIRECO demonstrated significant endothelial dysfunction measured by blunted endothelium-dependent vasorelaxation to acetylcholine, which was normalized by a specific Nox2 NADPH oxidase inhibitor. Insulin-stimulated phosphorylation of protein kinase B was increased in hIRECO EC as was Nox2 NADPH oxidase-dependent generation of superoxide, whereas insulin-stimulated and shear stress-stimulated eNOS activations were blunted. Phosphorylation at the inhibitory residue Y657 of eNOS and expression of proline-rich tyrosine kinase 2 that phosphorylates this residue were significantly higher in hIRECO EC. Inhibition of proline-rich tyrosine kinase 2 improved insulin-induced and shear stress-induced eNOS activation in hIRECO EC. Conclusions: Enhancing insulin sensitivity specifically in EC leads to a paradoxical decline in endothelial function, mediated by increased tyrosine phosphorylation of eNOS and excess Nox2-derived superoxide. Increased EC insulin sensitivity leads to a proatherosclerotic imbalance between NO and superoxide. Inhibition of proline-rich tyrosine kinase 2 restores insulin-induced and shear stress-induced NO production. This study demonstrates for the first time that increased endothelial insulin sensitivity leads to a proatherosclerotic imbalance between NO and superoxide.

AB - Rationale: In the endothelium, insulin stimulates endothelial NO synthase (eNOS) to generate the antiatherosclerotic signaling radical NO. Insulin-resistant type 2 diabetes mellitus is associated with reduced NO availability and accelerated atherosclerosis. The effect of enhancing endothelial insulin sensitivity on NO availability is unclear. Objective: To answer this question, we generated a mouse with endothelial cell (EC)-specific overexpression of the human insulin receptor (hIRECO) using the Tie2 promoter-enhancer. Methods and Results: hIRECO demonstrated significant endothelial dysfunction measured by blunted endothelium-dependent vasorelaxation to acetylcholine, which was normalized by a specific Nox2 NADPH oxidase inhibitor. Insulin-stimulated phosphorylation of protein kinase B was increased in hIRECO EC as was Nox2 NADPH oxidase-dependent generation of superoxide, whereas insulin-stimulated and shear stress-stimulated eNOS activations were blunted. Phosphorylation at the inhibitory residue Y657 of eNOS and expression of proline-rich tyrosine kinase 2 that phosphorylates this residue were significantly higher in hIRECO EC. Inhibition of proline-rich tyrosine kinase 2 improved insulin-induced and shear stress-induced eNOS activation in hIRECO EC. Conclusions: Enhancing insulin sensitivity specifically in EC leads to a paradoxical decline in endothelial function, mediated by increased tyrosine phosphorylation of eNOS and excess Nox2-derived superoxide. Increased EC insulin sensitivity leads to a proatherosclerotic imbalance between NO and superoxide. Inhibition of proline-rich tyrosine kinase 2 restores insulin-induced and shear stress-induced NO production. This study demonstrates for the first time that increased endothelial insulin sensitivity leads to a proatherosclerotic imbalance between NO and superoxide.

KW - diabetes mellitus

KW - insulin

KW - insulin resistance

KW - reactive oxygen species

KW - superoxide

UR - http://www.scopus.com/inward/record.url?scp=85004072316&partnerID=8YFLogxK

U2 - 10.1161/CIRCRESAHA.116.309678

DO - 10.1161/CIRCRESAHA.116.309678

M3 - Article

AN - SCOPUS:85004072316

SN - 0009-7330

VL - 120

SP - 784

EP - 798

JO - Circulation Research

JF - Circulation Research

IS - 5

ER -