Abstract 20699: Reduction of Endothelial Arnt Mediates Vascular Dysfunction in Diabetes
Introduction: Endothelial dysfunction, a central hallmark of diabetes, predisposes diabetic patients to a number of cardiovascular complications. We have previously shown that ARNT is a critical regulator of metabolism in the heart. However, its role in endothelial cells (ECs) is largely unknown.
Hypothesis: Here, we hypothesize that reduced ARNT expression in the endothelium mediates endothelial dysfunction in diabetes.
Methods and Results: Primary cardiac vascular endothelial cells (mCVECs) were isolated from diabetic (DB/DB) mouse hearts and confirmed using vWF staining and flow cytometry. We found that endothelial ARNT expression was significantly reduced in ECs from both diabetic rodents and humans (diabetic donors). To further investigate the role of ARNT in ECs, we ablated ARNT function specifically in adult murine vascular ECs (ecARNT-/-) by crossing ARNT flox/flox mice with inducible Cre recombinase mice under the control of the VE-Cadherin promoter, followed by the administration of oral tamoxifen chow for two weeks. Deletion of ARNT in ECs was confirmed at mRNA and protein levels from primary cells isolated from knock out mice. ecARNT-/- mice displayed aberrant endothelial cell ultrastructure, blunted wound healing and reduced blood flow recovery following hind limb ischemia. Interestingly, the mice also showed cardiac hypertrophy, and worsened cardiac function following high fat chow treatment (p<0.05, n=6) compared to control mice (WT with high-fat chow). In vitro, siRNA was used to reduce ARNT expression in ECs. siARNT-treated ECs displayed impaired tube formation and reduced cell migration in response to high glucose treatment. We also showed a decrease in VEGF mRNA expression in ecARNT-/- mice compared to controls (p<0.01), while HIF-1-alpha levels were unchanged. Taken together, this data suggests that a reduction in endothelial ARNT during diabetes may mediate endothelial dysfunction and impaired angiogenesis through the VEGF pathway.
Conclusions: Endothelial ARNT may be a critical mediator of endothelial function and could serve as a therapeutic target for diabetic cardiovascular diseases.
Author Disclosures: M. Knapp: None. M. Zheng: None. N. Sladojevic: None. Q. Zhao: None. J. Liao: None. R. Wu: None.
- © 2016 by American Heart Association, Inc.