Experimental Approaches to Study Endothelial Responses to Shear Stress.

SIGNIFICANCE: Shear stress controls multiple physiological processes in endothelial cells (ECs). RECENT ADVANCES: The response of ECs to shear has been studied using a range of in vitro and in vivo models. CRITICAL ISSUES: This article describes some of the experimental techniques that can be used to study endothelial responses to shear stress. It includes an appraisal of large animal, rodent, and zebrafish models of vascular mechanoresponsiveness. It also describes several bioreactors to apply flow to cells and physical methods to separate mechanoresponses from mass transport mechanisms. FUTURE DIRECTIONS: We conclude that combining in vitro and in vivo approaches can provide a detailed mechanistic view of vascular responses to force and that high-throughput systems are required for unbiased assessment of the function of shear-induced molecules. Antioxid. Redox Signal. 25, 389-400.

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.