Selective inhibition of inhibitory kappa B kinase‐ β abrogates induction of nitric oxide synthase in lipopolysaccharide‐stimulated rat aortic smooth muscle cells

In this study, we utilised a number of adenoviral constructs in order to examine the role of intermediates of the NF‐ κ B pathway in the regulation of inducible nitric oxide synthase (iNOS) induction in rat aortic smooth muscle cells (RASMCs). Lipopolysaccharide (LPS) stimulated a significant increase in iNOS induction and NF‐ κ B DNA binding. These parameters were substantially reduced by overexpression of a wild‐type I κ ‐B α adenoviral construct (Ad.I κ ‐B α ), confirming a role for NF‐ κ B in iNOS induction. Infection with a dominant‐negative IKK α adenoviral construct (Ad.IKK α +/− ) did not significantly affect iNOS induction, NF‐ κ B DNA binding or I κ ‐B α loss. Infection of RASMCs with adenovirus encoding a dominant‐negative IKK β (Ad.IKK β +/− ) essentially abolished iNOS induction and activation of the NF‐ κ B pathway. Pretreatment of RASMCs with a novel specific inhibitor of IKK β , SC‐514, significantly reduced iNOS induction, NF‐ κ B DNA binding and I‐ κ B α loss in a concentration‐dependent manner. In both RASMCs and human umbilical vein endothelial cells (HUVECs), infection with Ad.IKK β +/− also inhibited COX‐2 expression in response to LPS. However, Ad.IKK α +/− was again without effect. These data suggest that IKK β plays a predominant, selective role in the regulation of NF‐ κ B‐dependent induction of iNOS in RASMCs.British Journal of Pharmacology (2005) 146 , 217–225. doi: 10.1038/sj.bjp.0706308