Downregulation of vascular endothelial growth factor receptor-2 under oxidative stress conditions is mediated by -transduction repeat-containing protein via glycogen synthase kinase-3β signaling

作者：Wu, Wen; Zhang, Daimin; Pan, Daorong; Zuo, Guangfeng; Ren, Xiaomin; Chen, Shaoliang^*

来源：International Journal of Molecular Medicine, 2016, 37(4): 911-920.

DOI：10.3892/ijmm.2016.2493

• vascular endothelial growth factor receptor-2
• oxidase stress
• hyperglycemia
• beta-transduction repeat-containing protein
• glycogen synthase kinase-3 beta

Vascular endothelial growth factor receptor-2 (VEGFR-2), which is a key determinant of the angiogenecic response, is decreased in diabetic mice under oxidative stress beta-transduction repeat-containing protein (-TrCP) has been reported to participate in VEGFR-2 degradation in thyroid cancer cells. Additionally, glycogen synthase kinase-3 beta (GSK-3) acts as a mediator in the beta-TrCP-induced degradation of several proteins. However, the role played by beta-TrCP and GSK-3 in the degradation of VEGFR-2 in endothelial cells where hyperglycemia had been induced was not fully understood. In the present study, we aimed to analyze the mechanisms of VEGFR-2 degradation by studying excess reactive oxygen species (ROS) induced by hyperglycemia or glucose oxidase (GO). Human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of glucose (6.6, 19.8 and 33 mM), mannitol (33 mM) and GO (1 U/ml). Angiogenic function, ROS levels, the co-location of VEGFR-2 and beta-TrCP were evaluated. Cells were collected for RT-qPCR and western blot analysis. We noted that angiogenesis was impaired upon increasing the glucose concentration. When HUVECs were in a hyperglycemic state, ROS production increased, comparable to exposure to GO; GO catalyzes oxidation of glucose into H2O2 and D-glucono-delta-lactone. Phosphorylated VEGFR-2 was reduced by hyperglycemia while total VEGFR-2 was almost unaltered. However, VEGFR-2 was reduced when directly exposed to ROS, with resultant co-location of beta-TrCP and VEGFR-2. Through a co-immunoprecipitation assay, we noted that ubiquitinated VEGFR-2 was significantly augmented by excess ROS. Decreased VEGFR-2 caused by ROS was ameliorated by beta-TrCP siRNA, proteasome inhibitor MG132 and GSK-3 activity inhibitor (lithium chloride and SB216763). We suggest that redundant ROS reduces VEGFR-2 through beta-TrCP-mediated VEGFR-2 degradation, which is postulated to be regulated by GSK-3.

• 出版日期2016-4
• 单位南京医科大学