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Vascular biology

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Acute intensive insulin therapy exacerbates diabetic blood-retinal barrier breakdown via hypoxia-inducible factor-1α and VEGF
Vassiliki Poulaki, … , George D. Yancopoulos, Anthony P. Adamis
Vassiliki Poulaki, … , George D. Yancopoulos, Anthony P. Adamis
Published March 15, 2002
Citation Information: J Clin Invest. 2002;109(6):805-815. https://doi.org/10.1172/JCI13776.
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Acute intensive insulin therapy exacerbates diabetic blood-retinal barrier breakdown via hypoxia-inducible factor-1α and VEGF

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Abstract

Acute intensive insulin therapy is an independent risk factor for diabetic retinopathy. Here we demonstrate that acute intensive insulin therapy markedly increases VEGF mRNA and protein levels in the retinae of diabetic rats. Retinal nuclear extracts from insulin-treated rats contain higher hypoxia-inducible factor-1α (HIF-1α) levels and demonstrate increased HIF-1α–dependent binding to hypoxia-responsive elements in the VEGF promoter. Blood-retinal barrier breakdown is markedly increased with acute intensive insulin therapy but can be reversed by treating animals with a fusion protein containing a soluble form of the VEGF receptor Flt; a control fusion protein has no such protective effect. The insulin-induced retinal HIF-1α and VEGF increases and the related blood-retinal barrier breakdown are suppressed by inhibitors of p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol (PI) 3-kinase, but not inhibitors of p42/p44 MAPK or protein kinase C. Taken together, these findings indicate that acute intensive insulin therapy produces a transient worsening of diabetic blood-retinal barrier breakdown via an HIF-1α–mediated increase in retinal VEGF expression. Insulin-induced VEGF expression requires p38 MAPK and PI 3-kinase, whereas hyperglycemia-induced VEGF expression is HIF-1α–independent and requires PKC and p42/p44 MAPK. To our knowledge, these data are the first to identify a specific mechanism for the transient worsening of diabetic retinopathy, specifically blood-retinal barrier breakdown, that follows the institution of intensive insulin therapy.

Authors

Vassiliki Poulaki, Wenying Qin, Antonia M. Joussen, Peter Hurlbut, Stanley J. Wiegand, John Rudge, George D. Yancopoulos, Anthony P. Adamis

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Oxidation of the zinc-thiolate complex and uncoupling of endothelial nitric oxide synthase by peroxynitrite
Ming-Hui Zou, … , Chaomei Shi, Richard A. Cohen
Ming-Hui Zou, … , Chaomei Shi, Richard A. Cohen
Published March 15, 2002
Citation Information: J Clin Invest. 2002;109(6):817-826. https://doi.org/10.1172/JCI14442.
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Oxidation of the zinc-thiolate complex and uncoupling of endothelial nitric oxide synthase by peroxynitrite

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Abstract

Nitric oxide (NO) is produced by NO synthase (NOS) in many cells and plays important roles in the neuronal, muscular, cardiovascular, and immune systems. In various disease conditions, all three types of NOS (neuronal, inducible, and endothelial) are reported to generate oxidants through unknown mechanisms. We present here the first evidence that peroxynitrite (ONOO–) releases zinc from the zinc-thiolate cluster of endothelial NOS (eNOS) and presumably forms disulfide bonds between the monomers. As a result, disruption of the otherwise SDS-resistant eNOS dimers occurs under reducing conditions. eNOS catalytic activity is exquisitely sensitive to ONOO–, which decreases NO synthesis and increases superoxide anion (O2.–) production by the enzyme. The reducing cofactor tetrahydrobiopterin is not oxidized, nor does it prevent oxidation of eNOS by the same low concentrations of OONO–. Furthermore, eNOS derived from endothelial cells exposed to elevated glucose produces more O2.–, and, like eNOS purified from diabetic LDL receptor–deficient mice, contains less zinc and fewer SDS-resistant dimers. Hence, eNOS exposure to oxidants including ONOO– causes increased enzymatic uncoupling and generation of O2.– in diabetes, contributing further to endothelial cell oxidant stress. Regulation of the zinc-thiolate center of NOS by ONOO– provides a novel mechanism for modulation of the enzyme function in disease.

Authors

Ming-Hui Zou, Chaomei Shi, Richard A. Cohen

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MiR-33 fine-tunes atherosclerotic plaque inflammation
Mireille Ouimet, Hasini Ediriweera, and colleagues show that miR-33 controls the macrophage inflammatory program and promotes atherosclerotic plaque development…
Published October 26, 2015
Scientific Show StopperVascular biology

Contracting lacteals send lipids down the drain
Kibaek Choe, Jeon Yeob Jang, Intae Park and colleagues visualize lipid drainage through lacteals using intravital, video-rate microscopy…
Published October 5, 2015
Scientific Show StopperVascular biology

FOXC2 keeps lymphatic vessels leak-proof
Amélie Sabine and colleagues demonstrate that disturbed flow in lymphatic vasculature induces expression of the transcription factor FOXC2, which is essential for maintaining normal endothelial cell morphology and vessel integrity…
Published September 21, 2015
Scientific Show StopperVascular biology

Venous malformation model provides therapeutic insight
Elisa Boscolo and colleagues develop a murine model of venous malformation and demonstrate that rapamycin improves clinical symptoms of in this model and in patients…
Published August 10, 2015
Scientific Show StopperVascular biology

Lymphatic valves grow with the flow
Daniel Sweet and colleagues reveal that lymph flow is essential for lymphatic vessel maturation…
Published July 27, 2015
Scientific Show StopperVascular biology

GATA2 serves as a lymphatic rheostat
Jan Kazenwadel, Kelly Betterman, and colleagues reveal that the transcription factor GATA2 is essential for lymphatic valve development and maintenance…
Published July 27, 2015
Scientific Show StopperVascular biology

Factoring in factor XII in hereditary angioedema III
Jenny Björkqvist and colleagues elucidate the mechanism by which hereditary angioedema III-associated factor XII promotes vascular leakage…
Published July 20, 2015
Scientific Show StopperVascular biology

Regional regulation of atherosclerosis
Yogendra Kanthi, Matthew Hyman, and colleagues reveal that CD39 is regulated by blood flow and is protective against atherosclerosis…
Published June 29, 2015
Scientific Show StopperVascular biology
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