Critical effect of VEGF in the process of endothelial cell apoptosis induced by high glucose

Abstract

The underlying molecular mechanism whereby hyperglycemia causes endothelial cell apoptosis is not well understood. This study aims to elucidate the role of survival factor VEGF involved in the apoptosis of endothelial cells induced by elevated glucose. The present study confirmed that high concentration of glucose (25 mmol/l) significantly increased the apoptotic cell number in cultured primary human umbilical vein endothelial cells (HUVEC). Up-regulation of Bax/Bcl-2 ratio and activation of caspase-3 induced by high glucose suggested that mitochondria apoptosis pathway was involved. High glucose significantly reduced VEGF expression in HUVEC both at mRNA and protein levels. p42/44 MAPK phosphorylation was transitory attenuated when exposed to high glucose and preceded VEGF reduction, thus suggesting down-regulation of VEGF through inhibition of p42/44 MAPK. Addition of VEGF prevented HUVEC apoptosis from high glucose exposure. Moreover, elevated reactive oxygen species (ROS) generation, calcium overload, Bax/Bcl-2 ratio, caspase-3 activation in HUVEC induced by high glucose were reversed by pre-challenge with VEGF. This may represent a mechanism for the anti-apoptotic effect of VEGF. These results suggest that down-regulation of VEGF plays a critical role in apoptosis of endothelial cells induced by high glucose and restoration of VEGF might have benefits in the early stage of diabetic endothelial dysfunction.

The Virtual System of Organism, on the Verge of Apoptosis and Renewal Leading to Survival

“…We demonstrated there was a different response to plant extract with cellobiose complex (cellobiose, sulphur, selenium and vitamin C) and to solution of cellobiose in immortalized MEF wt cells in contrast to primary MEF wt cells, where there was no significant effect, suggesting there were some differences in the receptors in the cells membrane, by which molecules could enter the cell, what was also previously explored by Pelengaris et al, [1]. In immortalized MEF wt cells we observed there was a dose response to plant extract in higher concentrations from 0.1 mg/mL to 1 mg/mL, but this was not in linear correlation with the selected dosage range in the plant extract, where much lower concentrations were needed for the same effect of apoptosis and cell death [4,5,15,22]. For example the concentration of the plant extract of 1 µg/mL induced 28.10% of apoptosis in immortalized MEF wt cells, while 1.000x higher concentration of the mentioned extract induced 18.77% of apoptosis due to the fact that in higher concentrations the cells underwent cell death or simply bursted in the process (Figure 6) [15].…”

“…In white 96-well-plate we transferred 40 µl of each samples and added 50 µl of 2X caspase buffer/1M DTT and 10 µl of DEVD substrate. We gathered 40 µg of protein from cells, untreated and treated with the plant extract in the presence or absence of inhibitor Z-VAD-FMK, to determine caspase activity and by measuring the proteolytic cleavage of the fluorogenic substrate Ac-DEVD-AFC (Bachem) has also shown in standard protocols [4]. Before absorbance measurement the plate was incubated at 37 0 C in the incubator with 5% CO 2 .…”

“…To date, several pathways for activation of caspases and apoptosis have been identified including the death receptor pathway mediated by caspase 8, the mitochondrial pathway mediated by cytochrome-c release and caspase 9 activation [1][2][3][4].…”

In Vitro Study Examining the Activity of Vildagliptin and Sitagliptin against Hyperglycemia-Induced Effects in Human Umbilical Vein Endothelial Cells

“…We focused on apoptosis as it is a wellestablished effect triggered by hyperglycemia [21]. Accordingly, it has been previously shown that HG-induced apoptosis in HUVECs is accompanied by increased Bax/Bcl 2 ratio [21][22][23], that can be reverted, at least partly, by treatment with DDP-4 inhibitors [7]. Second, we did not investigate the possible effects of DDP-4 inhibitors on nitric oxide synthase (eNOS) expression and activity, as it was well beyond the scope of this study and in vitro and in vivo studies have already provided evidence linking GLP-1, DDP-4 inhibitors, eNOS and endothelial function [24][25][26][27][28].…”

Microarray Analysis of Gene Expression by Rhei Rhizoma Water Extracts in a Hypoxia Model of Cultured Neurons

“…It has been shown that VEGF can prevent cell death in various conditions. For example, VEGF prevented apoptosis of human umbilical vein endothelial cells (HUVEC) from high glucose exposure [63]. In high glucose exposure, pretreatment of VEGF lowered ROS generation, calcium overload, Bax/Bcl-2 ratio, caspase-3 activation in HUVEC.…”