PMID:23144758

Citation	Meng, D, Mei, A, Liu, J, Kang, X, Shi, X, Qian, R and Chen, S (2012) NADPH Oxidase 4 Mediates Insulin-Stimulated HIF-1α and VEGF Expression, and Angiogenesis In Vitro. PLoS ONE 7:e48393
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-1α 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-1α 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-β 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 of VEGF. Downregulation of Nox4 expression decreased insulin-stimulated mRNA and protein expression of HIF-1α, but did not change the rate of HIF-1α degradation. Inhibition of Nox4 impaired insulin-stimulated VEGF expression, cell migration, cell proliferation, and tube formation in HMVECs. Our data indicate that Nox4-derived ROS are essential for HIF-1α-dependent VEGF expression, and angiogenesis in vitro induced by insulin. Nox4 may be an attractive therapeutic target for diabetic retinopathy caused by intensive insulin treatment.
Links	PubMed PMC3483150 Online version:10.1371/journal.pone.0048393
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:NOX4	involved_in	GO:0010467: gene expression	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
HUMAN:NOX4		GO:0043020 : NADPH oxidase complex	ECO:0000314:		C		Figure 2 shows "Nox4 is involved in insulin-stimulated insulin receptor and IRS tyrosine phosphorylation, ERK1/2, and AKT activation".	complete CACAO 6095
HUMAN:NOX4		GO:0010467: gene expression	ECO:0000315:		P		Figure 4 shows Nox4 mediates insulin-induced HIF-1α mRNA and protein expression	complete CACAO 6096
HUMAN:NOX4		GO:0043020: NADPH oxidase complex	ECO:0000314:		C		Figure 6 shows Nox4 mediates insulin-induced HMVEC migration, proliferation, and angiogenesis in vitro.	complete CACAO 6097

References

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