c-Jun N-terminal kinase 2 deficiency protects against hypercholesterolemia-induced endothelial dysfunction and oxidative stress

• Background— Hypercholesterolemia-induced endothelial dysfunction due to excessive production of reactive oxygen species is a major trigger of atherogenesis. The c-Jun-N-terminal kinases (JNKs) are activated by oxidative stress and play a key role in atherogenesis and inflammation. We investigated whether JNK2 deletion protects from hypercholesterolemia-induced endothelial dysfunction and oxidative stress. Methods and Results— Male JNK2 knockout (JNK2−/−) and wild-type (WT) mice (8 weeks old) were fed either a high-cholesterol diet (HCD; 1.25% total cholesterol) or a normal diet for 14 weeks. Aortic lysates of WT mice fed a HCD showed an increase in JNK phosphorylation compared with WT mice fed a normal diet (P<0.05). Endothelium-dependent relaxations to acetylcholine were impaired in WT HCD mice (P<0.05 versus WT normal diet). In contrast, JNK2−/− HCD mice did not exhibit endothelial dysfunction (96±5% maximal relaxation in response to acetylcholine; P<0.05 versus WT HCD). Endothelium-independent relaxations were identical in all groups. A hypercholesterolemia-induced decrease in nitric oxide (NO) release of endothelial cells was found in WT but not in JNK2−/− mice. In parallel, endothelial NO synthase expression was upregulated only in JNK2−/− HCD animals, whereas the expression of antioxidant defense systems such as extracellular superoxide dismutase and manganese superoxide dismutase was decreased in WT but not in JNK2−/− HCD mice. In contrast to JNK2−/− mice, WT HCD displayed an increase in O2− and ONOO− concentrations as well as nitrotyrosine staining and peroxidation.

Nyckelord

atherosclerosis

endothelium

nitric oxide

JNK kinase

reactive oxygen species

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