Intervention of exogenous VEGF protect brain microvascular endothelial cells from hypoxia-induced injury by regulating PLCγ/RAS/ERK and PI3K/AKT pathways

Abstract

Ischemic stroke rapidly increases the expression level of vascular endothelial growth factor (VEGF), which promotes neovascularization during hypoxia. However, the effect and mechanism of VEGF intervention on cerebrovascular formation remain unclear.Therefore, our research discussed the protective effect of exogenous VEGF on cells in hypoxia environment in cerebral microvascular endothelial cells, simulating ischemic stroke in hypoxic environment. Firstly, we detected the proliferation and apoptosis of cerebral microvascular endothelial cells under hypoxia environment, as well the expression levels of VEGF-E, vascular endothelial growth factor re-ceptor-2 (VEGFR-2), BCL2, PRKCE and PINK1. Moreover, immunofluorescence and western blotting were used to verify the regulation of exogenous VEGF-E on VEGFR-2 expression in hypoxic or normal oxygen environment. Lastly, we manipulated the concentration of VEGF-E in the culture medium to investigate its impact on phospholipase Cγ1 (PLCγ1)/extracellular signaling regulatory protein kinase (ERK) -1/2 and protein kinase B (AKT) pathways. Additionally, we employed a PLCγ1 inhibitor (U73122) to investigate its impact on proliferation and PLCγ1/ERK pathways.The results show that hypoxia inhibited the proliferation of cerebral microvascular endothelial cells, promoted cell apoptosis, significantly up-regulated the expression of VEGF-E, VEGFR-2, PRKCE and PINK1, but down-regulated the expression of BCL2. Interference from exogenous VEGF-E activated PLCγ1/ERK-1/2 and AKT pathways, promoting cell proliferation and inhibiting apoptosis of hypoxic brain microvascular endothelial cells.In summary, exogenous VEGF-E prevents hypoxia-induced damage to cerebral microvascular endothelial cells by activating the PLCγ1/ERK and AKT pathways. This action inhibits the apoptosis pathway in hypoxic cerebral microvascular endothelial cells, thereby safeguarding the blood-brain barrier and the nervous system.