Nox activator 1: a potential target for modulation of vascular reactive oxygen species in atherosclerotic arteries.
BACKGROUND
Despite a concerted effort by many laboratories, the critical subunits that participate in vascular smooth muscle cell (VSMC) NADPH oxidase function have yet to be elucidated. Given the potential therapeutic importance of cell-specific inhibition of NADPH oxidase, we investigated the role of Nox activator 1 (NoxA1), a homolog of p67phox, in VSMC NADPH oxidase function and atherosclerosis.


RESULTS
The presence of NoxA1 in mouse aortic VSMCs was confirmed by reverse-transcription polymerase chain reaction and sequencing. NoxA1/p47phox interaction after thrombin treatment was observed by immunoprecipitation/Western analysis of lysates from p47phox(-/-) VSMCs transfected with adenoviral HA-NoxA1 and Myc-p47phox. Infection with adenoviral NoxA1 significantly enhanced thrombin-induced reactive oxygen species generation in wild-type but not in p47phox(-/-) and Nox1(-/-) VSMCs. Thrombin-induced reactive oxygen species production and VSMC proliferation were significantly reduced after downregulation of NoxA1 with shRNA. Infection with NoxA1 shRNA but not scrambled shRNA significantly decreased thrombin-induced activation of the redox-sensitive protein kinases (Janus kinase 2, Akt, and p38 mitogen-activated protein kinase) in VSMCs. Adenovirus-mediated overexpression of NoxA1 in guidewire-injured mouse carotid arteries significantly increased superoxide production in medial VSMCs and enhanced neointimal hyperplasia. NoxA1 expression was significantly increased in aortas and atherosclerotic lesions of ApoE(-/-) mice compared with age-matched wild-type mice. Furthermore, in contrast to p67phox, immunoreactive NoxA1 is present in intimal and medial SMCs of human early carotid atherosclerotic lesions.


CONCLUSIONS
NoxA1 is the functional homolog of p67phox in VSMCs that regulates redox signaling and VSMC phenotype. These findings support the potential for modulation of NoxA1 expression as a viable approach for the treatment of vascular diseases.
Niu
Xi-Lin
XL
McAllister Heart Institute, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599-7005, USA.
Madamanchi
Nageswara R
NR
Vendrov
Aleksandr E
AE
Tchivilev
Igor
I
Rojas
Mauricio
M
Madamanchi
Chaitanya
C
Brandes
Ralph P
RP
Krause
Karl-Heinz
KH
Humphries
Julia
J
Smith
Alberto
A
Burnand
Kevin G
KG
Runge
Marschall S
MS
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics / Q000378:metabolism; D050197:Atherosclerosis / Q000378:metabolism* / Q000473:pathology; D002339:Carotid Arteries / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D001057:Apolipoproteins E; C476420:NOXA1 protein, human; C472286:Noxa1 protein, mouse; D011506:Proteins; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1