IkappaBalpha-dependent regulation of low-shear flow-induced NF-kappa B activity: role of nitric oxide.
We have investigated the role of inhibitor kappaBalpha (IkappaBalpha) in the activation of nuclear factor kappaB (NF-kappaB) observed in human aortic endothelial cells (HAEC) undergoing a low shear stress of 2 dynes/cm(2). Low shear for 6 h resulted in a reduction of IkappaBalpha levels, an activation of NF-kappaB, and an increase in kappaB-dependent vascular cell adhesion molecule 1 (VCAM-1) mRNA expression and endothelial-monocyte adhesion. Overexpression of IkappaBalpha in HAEC attenuated all of these shear-induced responses. These results suggest that downregulation of IkappaBalpha is the major factor in the low shear-induced activation of NF-kappaB in HAEC. We then investigated the role of nitric oxide (NO) in the regulation of IkappaBalpha/NF-kappaB. Overexpression of endothelial nitric oxide synthase (eNOS) inhibited NF-kappaB activation in HAEC exposed to 6 h of low shear stress. Addition of the structurally unrelated NO donors S-nitrosoglutathione (300 microM) or sodium nitroprusside (1 mM) before low shear stress significantly increased cytoplasmic IkappaBalpha and concomitantly reduced NF-kappaB binding activity and kappaB-dependent VCAM-1 promoter activity. Together, these data suggest that NO may play a major role in the regulation of IkappaBalpha levels in HAEC and that the application of low shear flow increases NF-kappaB activity by attenuating NO generation and thus IkappaBalpha levels.
Mohan
Sumathy
S
Department of Pathology, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA. mohan@uthscsa.edu
Hamuro
Masao
M
Sorescu
George P
GP
Koyoma
Koichi
K
Sprague
Eugene A
EA
Jo
Hanjoong
H
Valente
Anthony J
AJ
Prihoda
Thomas J
TJ
Natarajan
Mohan
M
D001011:Aorta / Q000166:cytology / Q000502:physiology; D002478:Cells, Cultured; D015536:Down-Regulation; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D020672:I-kappa B Proteins / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000502:physiology; D052250:Nitric Oxide Synthase Type III; D009574:Nitro Compounds / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D013314:Stress, Mechanical; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics
D020672:I-kappa B Proteins; D016328:NF-kappa B; D020030:Nitric Oxide Donors; D009574:Nitro Compounds; D012333:RNA, Messenger; C116027:S-nitroglutathione; D019010:Vascular Cell Adhesion Molecule-1; D009599:Nitroprusside; D009569:Nitric Oxide; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D005978:Glutathione