Hypoxia induces the proliferation of endothelial progenitor cells via upregulation of Apelin/APLNR/MAPK signaling

Abstract

Abstract. Endothelial progenitor cells (EPCs) can form new vessels through differentiation into endothelial cells (ECs), thus being important in the prevention of hypoxia/ischemia. Apelin can activate different signaling pathways through its receptor, APLNR, which regulate diverse biological functions, including cardiovascular function. However, the molecular mechanism by which Apelin mediates hypoxia-induced EPCs proliferation remain to be fully elucidated. The present study aimed to determine the role of Apelin/APLNR signaling in hypoxia-induced proliferation of EPCs. MTT assay was used to determine cell proliferation. Reverse transcription-quantitative polymerase chain reaction and western blotting analysis were conducted to examine mRNA and protein expression. It was revealed that hypoxia promoted the proliferation of the EPCs. Further investigation demonstrated that hypoxia promoted the expression levels of hypoxia-inducible factor (HIF)-1α, Apelin and APLNR in the EPCs. In addition, upregulation of Apelin or APLNR promoted the hypoxia-induced proliferation of the EPCs, while knockdown of Apelin or APLNR by small interfering RNA suppressed the hypoxia-induced proliferation of the EPCs, suggesting that the Apelin/APLNR axis is involved in hypoxia-induced proliferation of EPCs. Furthermore, pretreatment of the EPCs with SB-239063 or PD98059, two inhibitors of mitogen-activated protein kinase (MAPK), eliminated the Apelin upregulation-induced EPC proliferation, suggesting that MAPK signaling is a downstream effecter of Apelin/APLNR in EPCs. Therefore, the findings of the present study indicated that the production of HIF-1α, induced by hypoxia, activated the Apelin/APLNR and the downstream MAPK signaling pathways, leading to upregulated proliferation of the EPCs. These findings suggested that Apelin/APLNR signaling may be used as a potential therapeutic target for hypoxic/ischemic injury.

Apelin and stem cells: the role played in the cardiovascular system and energy metabolism

“…Overexpression of apelin in EPCs raises their angiogenic potential. These findings show the role of apelin in endothelial progenitor cell proliferation (Zhang et al, , ). Apelin‐overexpressing BMCs increases myocardial angiogenesis more efficiently than BMCs in post‐MI mice (Li et al, ).…”

“…These findings suggest that apelin may be used as a promising therapeutic strategy in the treatment of oxidative stress associated metabolic diseases (Zhu et al, ; Than et al, ). Additionally, apelin has effects on angiogenesis in hypoxic conditions through increasing the proliferation of endothelial progenitor cells (Zhang et al, , ).…”

“…Apelin signaling has an effect on the EPCs proliferation under hypoxic conditions. Apelin‐transfected cells have a higher proliferative capacity than the untransfected cells (Zhang et al, , ). This peptide upregulates the angiogenic factor expression in BMCs (Li et al, ).…”

Clinical significance of the phosphorylation of MAPK and protein expression of cyclin D1 in human osteosarcoma tissues

“…As the axis of several types of signal channels, mitogen-activated protein kinase (MAPK) cascade activation is a key member in the receipt of signals, which are transferred and carried by membrane receptors into the nucleus (6,7), which is key to numerous signaling channels associated with cell proliferation.…”

Hypoxia accelerates intraplaque neovascularization derived from endothelial progenitor cells in carotid stenosis

“…12 Recent studies have suggested that the overexpression of HIF-1a enhances the proliferation, invasion, cell survival, and in vitro capillary sprout formation of the EPC population. 24,32 In this study, therefore, we aimed to clarify the relation among intraplaque hypoxia, EPCs, and microvessels that cause IPH.…”