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- Title
The natural protective mechanism against hyperglycemia in vascular endothelial cells: roles of the lipid peroxidation product 4-hydroxydodecadienal and peroxisome proliferator-activated receptor delta.
- Authors
Riahi Y; Sin-Malia Y; Cohen G; Alpert E; Gruzman A; Eckel J; Staels B; Guichardant M; Sasson S; Riahi, Yael; Sin-Malia, Yoav; Cohen, Guy; Alpert, Evgenia; Gruzman, Arie; Eckel, Juergen; Staels, Bart; Guichardant, Michel; Sasson, Shlomo
- Abstract
<bold>Objective: </bold>Vascular endothelial cells (VECs) downregulate their rate of glucose uptake in response to hyperglycemia by decreasing the expression of their typical glucose transporter GLUT-1. Hitherto, we discovered critical roles for the protein calreticulin and the arachidonic acid-metabolizing enzyme 12-lipoxygenase in this autoregulatory process. The hypothesis that 4-hydroxydodeca-(2E,6Z)-dienal (4-HDDE), the peroxidation product of 12-lipoxygenase, mediates this downregulatory mechanism by activating peroxisome proliferator-activated receptor (PPAR) delta was investigated.<bold>Research Design and Methods: </bold>Effects of 4-HDDE and PPARdelta on the glucose transport system and calreticulin expression in primary bovine aortic endothelial cells were evaluated by pharmacological and molecular interventions.<bold>Results: </bold>Using GW501516 (PPARdelta agonist) and GSK0660 (PPARdelta antagonist), we discovered that high-glucose-induced downregulation of the glucose transport system in VECs is mediated by PPARdelta. A PPAR-sensitive luciferase reporter assay in VECs revealed that high glucose markedly increased luciferase activity, while GSK0660 abolished it. High-performance liquid chromatography analysis showed that high-glucose incubation substantially elevated the generation of 4-HDDE in VECs. Treatment of VECs, exposed to normal glucose, with 4-HDDE mimicked high glucose and downregulated the glucose transport system and increased calreticulin expression. Like high glucose, 4-HDDE significantly activated PPARdelta in cells overexpressing human PPAR (hPPAR)delta but not hPPARalpha, -gamma1, or -gamma2. Moreover, silencing of PPARdelta prevented high-glucose-dependent alterations in GLUT-1 and calreticulin expression. Finally, specific binding of PPARdelta to a PPAR response element in the promoter region of the calreticulin gene was identified by utilizing a specific chromatin immunoprecipitation assay.<bold>Conclusions: </bold>Collectively, our data show that 4-HDDE plays a central role in the downregulation of glucose uptake in VECs by activating PPARdelta.
- Publication
Diabetes, 2010, Vol 59, Issue 4, p808
- ISSN
0012-1797
- Publication type
journal article
- DOI
10.2337/db09-1207