Induction of Vascular Insulin Resistance, Endothelin-1 Expression, and Acceleration of Atherosclerosis by the Overexpression of Protein Kinase C Isoform in the Endothelium

Subject codes: [134] Pathophysiology [138] Cell signaling/signal transduction [145] Genetically altered mice [95] Endothelium/vascular type/nitric oxide [96] Mechanism of atherosclerosis/growth factors [190] Type 2 diabetes In May 2013, the average time from submission to first decision for all original research papers submitted to Circulation Research was 15 days. ABSTRACT Rationale: Loss of insulin action on the endothelium can cause endothelial dysfunction and atherosclerosis. Hyperglycemia and elevated fatty acids induced by diabetes can activate protein kinase C (PKC)  isoforms and selectively inhibit insulin signaling via phosphatidylinositol 3-kinase (PI3K)/Akt pathway to inhibit the activation of endothelial nitric oxide synthase (eNOS) and metabolic actions. Objective: To demonstrate that overexpressing PKCβ2 isoform in endothelial cells can cause selective insulin resistance and exacerbate atherosclerosis in the aorta. Methods and Results: PKCβ2 isoform was overexpressed in endothelial cells using a promoter of vascular endothelial cell-cadherin (VE-Cadherin). These mice were cross-bred with ApoE-/-mice (Tg (Prkcb)ApoE-/-). On a Western diet, Tg(Prkcb)ApoE-/-and ApoE-/-mice did not differ in systemic insulin sensitivity, glucose tolerance, plasma lipid or blood pressure. Insulin action in endothelial cells and femoral artery from Tg(Prkcb)ApoE-/-mice were impaired by ~40% with respect to Akt/eNOS activation and leukocyte-endothelial cell binding increased in cultured lung endothelial cells from Tg(Prkcb)ApoE-/-mice compared to ApoE-/-mice. Basal and angiotensin stimulated big endothelin-1 (ET-1) levels were elevated in Tg(Prkcb)ApoE-/-mice compared to ApoE-/-mice. The severity of atherosclerosis in the aorta from Tg(Prkcb)ApoE-/-mice increased by ~70% as measured by en face fat staining and plaque content of the number of smooth muscle cells, macrophages and extracellular matrix. Conclusions: Specific PKCβ2 activation in the endothelial cells caused dysfunction and accelerated atherosclerosis due to loss of insulin-stimulated Akt/eNOS activation and angiotensin induced increases in ET-1 expression. Non-Standard Abbreviations and Acronyms: PKC protein kinase C ET-1 endothelin 1 eNOS endothelial nitric oxide synthase CVD cardiovascular disease apoE apolipoprotein E VCAM-1 vascular cell adhesion molecule-1 Ach acetylcholine SNP sodium nitroprusside Ang II angiotension II NO nitric oxide