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VEGF upregulates VEGF receptor-2 on human outer root sheath cells and stimulates proliferation through ERK pathway

Li, Wei, Lu, Zhong-Fa, Man, Xiao-Yong, Li, Chun-Ming, Zhou, Jiong, Chen, Jia-Qi, Yang, Xiao-Hong, Wu, Xian-Jie, Cai, Sui-Qing, Zheng, Min
Molecular biology reports 2012 v.39 no.9 pp. 8687-8694
Western blotting, angiogenesis, cell proliferation, dose response, fluorescent antibody technique, humans, messenger RNA, mitogen-activated protein kinase, phosphorylation, protein kinase C, reverse transcriptase polymerase chain reaction, signal transduction, vascular endothelial growth factor receptor-2, vascular endothelial growth factors
Vascular endothelial growth factor (VEGF) is a key regulator of physiological and pathological angiogenesis. The biological effects of VEGF are mediated by receptor tyrosine kinases. VEGF receptor-2, the primary receptor for VEGF, is thought to mediate most functional effects. In this study, we examined the expression and roles of VEGF receptor-2 on human outer root sheath cells (ORS). The expression of VEGFR-2 was determined at mRNA and protein levels by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Localization of VEGFR-2 in ORS cells was detected by immunofluorescence. The effect of VEGF on ORS cell proliferation was determined by MTT assays. Our data showed the expression of VEGFR-2 on ORS cells at both mRNA and protein levels. Immunostaining for VEGFR-2 demonstrated strong signal on cultured ORS cells. Exogenous VEGF₁₆₅ stimulated proliferation of ORS cells and upregulated expression of VEGFR-2 in a dose-dependent manner. Moreover, VEGF₁₆₅ induced phosphorylation of VEGFR-2, PLC-γ1, PKC-α, MEK, and p44/42 MAPK (ERK1/2) in a time-dependent manner. Taken together, human ORS cells express functional VEGF receptor-2 and exogenous VEGF₁₆₅ upregulates expression of VEGFR-2 and stimulates proliferation of ORS cells via VEGFR-2 mediated ERK signaling pathway.