Gene transfer of inducible nitric oxide synthase affords cardioprotection by upregulating heme oxygenase-1 via a nuclear factor-{kappa}B-dependent pathway.
BACKGROUND
Although inducible nitric oxide synthase (iNOS) is known to impart powerful protection against myocardial infarction, the mechanism for this salubrious action remains unclear.


RESULTS
Adenovirus-mediated iNOS gene transfer in mice resulted 48 to 72 hours later in increased expression not only of iNOS protein but also of heme oxygenase (HO)-1 mRNA and protein; HO-2 protein expression did not change. iNOS gene transfer markedly reduced infarct size in wild-type mice, but this effect was completely abrogated in HO-1(-/-) mice. At 48 hours after iNOS gene transfer, nuclear factor-kappaB was markedly activated. In transgenic mice with cardiomyocyte-restricted expression of a dominant negative mutant of IkappaBalpha (IkappaBalpha(S32A,S36A)), both basal HO-1 levels and upregulation of HO-1 by iNOS gene transfer were suppressed. Chromatin immunoprecipitation analysis of mouse hearts provided direct evidence that nuclear factor-kappaB subunits p50 and p65 were recruited to the HO-1 gene promoter (-468 to -459 bp) 48 hours after iNOS gene transfer.


CONCLUSIONS
This study demonstrates for the first time the existence of a close functional coupling between cardiac iNOS and cardiac HO-1: iNOS upregulates HO-1 by augmenting nuclear factor-kappaB binding to the region of the HO-1 gene promoter from -468 to -459 bp, and HO-1 then mediates the cardioprotective effects of iNOS. These results also reveal an important role of nuclear factor-kappaB in both basal and iNOS-induced expression of cardiac HO-1. Collectively, the present findings significantly expand our understanding of the regulation of cardiac HO-1 and of the mechanism whereby iNOS exerts its cardioprotective actions.
Li
Qianhong
Q
Division of Cardiology, University of Louisville, Louisville, KY 40292, USA.
Guo
Yiru
Y
Ou
Qinghui
Q
Cui
Chuanjue
C
Wu
Wen-Jian
WJ
Tan
Wei
W
Zhu
Xiaoping
X
Lanceta
Lilibeth B
LB
Sanganalmath
Santosh K
SK
Dawn
Buddhadeb
B
Shinmura
Ken
K
Rokosh
Gregg D
GD
Wang
Shuyan
S
Bolli
Roberto
R
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001663:Bilirubin / Q000378:metabolism; D001831:Body Temperature; D005260:Female; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D006321:Heart / Q000502:physiology*; D006339:Heart Rate; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D012333:RNA, Messenger; D000072000:NF-KappaB Inhibitor alpha; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051547:Heme Oxygenase-1; D001663:Bilirubin