Abstract MP250: Reduction In Endothelial Aryl Hydrocarbon Receptor Nuclear Translocator (arnt) Mediates Vascular Dysfunction In Mice With Type 2 Diabetes Mellitus

Abstract

Background: Endothelial dysfunction, especially at the microvasculature level, is one of the most deleterious events in diabetes. ARNT is a transcription factor that functions as a master regulator of glucose homeostasis, but its role in diabetic vascular complications is poorly understood. Results and method: We found a reduction in ARNT expression in microvascular endothelial cells (MVECs) derived from type 2 diabetic mice (db/db). Thus, we generated an inducible, EC-specific ARNT-knockout mutation ( Arnt ΔEC, ERT2) to address the hypothesis that aberrations in ARNT expression might contribute to the vascular deficiencies associated with diabetes. We show here that loss of ARNT in the endothelium mimics diabetic phenotypes, such as impairs blood flow recovery after hindlimb ischemia, delays wound healing, and exacerbates infiltration of pro-inflammatory neutrophils after myocardial infarction. Interestedly, the degree of these impairments in the KO mice was more remarkable in diabetic animals induced with high-fat chow. In addition, the siRNA-mediated knockdown of ARNT activity reduced tube formation and cell viability measurements in HUVECs cultured under high-glucose conditions. The Arnt ΔEC, ERT2 mutation also reduced measures of cell viability while increasing the production of reactive oxygen species (ROS) in MVECs isolated from mouse skeletal muscle, and the viability of Arnt ΔEC, ERT2 MVECs under high-glucose concentrations increased when the cells were treated with a ROS inhibitor. Conclusion: Collectively, these observations suggest that declines in endothelial ARNT expression contribute to the suppressed angiogenic phenotype in diabetic mice and that the cytoprotective effect of ARNT expression in ECs is at least partially mediated by declines in ROS production. Endothelial ARNT might be a critical mediator of endothelial function and could serve as a therapeutic target for diabetic complications.