Differential effects of diabetes on the expression of the gp91phox homologues nox1 and nox4.
The nox2-dependent NADPH oxidase was shown to be a major superoxide source in vascular disease, including diabetes. Smooth muscle cells of large arteries lack the phagocytic gp91phox subunit of the enzyme; however, two homologues have been identified in these cells, nox1 and nox4. It remained to be established whether also increases in protein levels of the nonphagocytic NADPH oxidase contribute to increased superoxide formation in diabetic vessels. To investigate changes in the expression of these homologues, we measured their expression in aortic vessels of type I diabetic rats. Eight weeks after streptozotocin treatment, we found a doubling in nox1 protein expression, while the expression of nox4 remained unchanged. This was associated with a significant increase in the NADPH oxidase activity in membrane fractions of diabetic heart and aortic tissue. Furthermore, we observed a decreased sensitivity of diabetic vessels to acetylcholine and nitroglycerin and a decrease in both acetylcholine-stimulated NO production and phosphorylation of VASP, despite an increase in endothelial NO synthase (NOSIII) expression. In addition, xanthine oxidase activity was markedly increased in plasma and 100,000 g supernatant of cardiac tissue of diabetic rats, while myocardial mitochondrial superoxide formation was only weakly enhanced. We conclude that in addition to phagocytic NADPH oxidase, also nonphagocytic, vascular NADPH oxidase subunit nox1, uncoupled NOSIII, and plasma xanthine oxidase contribute to endothelial dysfunction in the setting of diabetes mellitus.
The University Clinics Eppendorf, Division of Cardiology, Hamburg, Germany.
Maria C
MC
Wendt
Andreas
A
Daiber
Andrei L
AL
Kleschyov
Alexander
A
Mülsch
Karsten
K
Sydow
Eberhard
E
Schulz
Kai
K
Chen
John F
JF
Keaney
Bernard
B
Lassègue
Ulrich
U
Walter
Kathy K
KK
Griendling
Thomas
T
Münzel
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000201:enzymology; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000187:drug effects / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D042783:Endothelial Cells / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D008297:Male; D008840:Microfilament Proteins; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000096:biosynthesis*; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000096:biosynthesis*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000187:drug effects / Q000378:metabolism; D005996:Nitroglycerin / Q000494:pharmacology; D010750:Phosphoproteins / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism; D014665:Vasodilator Agents / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000378:metabolism; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D010750:Phosphoproteins; D014665:Vasodilator Agents; D000098662:Vasodilator-Stimulated Phosphoprotein; D013481:Superoxides; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D014969:Xanthine Oxidase; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C000614712:NOX1 protein, rat; C498911:Nox4 protein, rat; D005996:Nitroglycerin; D000109:Acetylcholine