nadph oxidase 4 mediates insulin-stimulated hif-1α and vegf expression, and angiogenesis in vitronadph氧化酶4调节刺激hif-1α和vegf的表达,并在体外血管生成.pdfVIP

NADPH Oxidase 4 Mediates Insulin-Stimulated HIF-1a and VEGF Expression, and Angiogenesis In Vitro 1 2 1 1 3 1 1 Dan Meng *, Aihong Mei , Junxu Liu , Xueling Kang , Xianglin Shi , Ruizhe Qian , Sifeng Chen 1 Department of Physiology and Pathophysiology, Fudan University Shanghai Medical College, Shanghai, China, 2 Department of Diagnosis, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, Shanghai, China, 3 Graduate Center for Toxicology, University of Kentucky, Lexington, Kentucky, United States of America Abstract Acute intensive insulin therapy causes a transient worsening of diabetic retinopathy in type 1 diabetes patients and is related to VEGF expression. Reactive oxygen species (ROS) have been shown to be involved in HIF-1a and VEGF expression induced by insulin, but the role of specific ROS sources has not been fully elucidated. In this study we examined the role of NADPH oxidase subunit 4 (Nox4) in insulin-stimulated HIF-1a and VEGF expression, and angiogenic responses in human microvascular endothelial cells (HMVECs). Here we demonstrate that knockdown of Nox4 by siRNA reduced insulin- stimulated ROS generation, the tyrosine phosphorylation of IR-b and IRS-1, but did not change the serine phosphorylation of IRS-1. Nox4 gene silencing had a much greater inhibitory effect on insulin-induced AKT activation than ERK1/2 activation, whereas it had little effect on the expression of the phosphatases such as MKP-1 and SHIP. Inhibition of Nox4 expression inhibited the transcriptional activity of VEGF through HIF-1. Overexpression of wild-type Nox4 was sufficient to increase VEGF transcriptional activity, and further enhanced insulin-stimulated the activation