Requirement of JNK1 for endothelial cell injury in atherogenesis

OBJECTIVE: The c-Jun N-terminal kinase (JNK) family regulates fundamental physiological processes including apoptosis and metabolism. Although JNK2 is known to promote foam cell formation during atherosclerosis, the potential role of JNK1 is uncertain. We examined the potential influence of JNK1 and its negative regulator, MAP kinase phosphatase-1 (MKP-1), on endothelial cell (EC) injury and early lesion formation using hypercholesterolemic LDLR(−/−) mice. METHODS AND RESULTS: To assess the function of JNK1 in early atherogenesis, we measured EC apoptosis and lesion formation in LDLR(−/−) or LDLR(−/−)/JNK1(−/−) mice exposed to a high fat diet for 6 weeks. En face staining using antibodies that recognise active, cleaved caspase-3 (apoptosis) or using Sudan IV (lipid deposition) revealed that genetic deletion of JNK1 reduced EC apoptosis and lesion formation in hypercholesterolemic mice. By contrast, although EC apoptosis was enhanced in LDLR(−/−)/MKP-1(−/−) mice compared to LDLR(−/−) mice, lesion formation was unaltered. CONCLUSION: We conclude that JNK1 is required for EC apoptosis and lipid deposition during early atherogenesis. Thus pharmacological inhibitors of JNK may reduce atherosclerosis by preventing EC injury as well as by influencing foam cell formation.