| First Author | Murphy WJ | Year | 1996 |
| Journal | J Endotoxin Res | Volume | 3 |
| Issue | 5 | Pages | 381-393 |
| Mgi Jnum | J:38024 | Mgi Id | MGI:85416 |
| Doi | 10.1177/096805199600300502 | Citation | Murphy WJ, et al. (1996) Both basal and enhancer kappa B elements are required for full induction of the mouse inducible nitric oxide synthase gene. J Endotoxin Res 3(5):381-393 |
| abstractText | The transcriptional regulatory region of the mouse inducible nitric oxide synthase (iNOS) gene has two kappa B elements, one enhancer-linked (kappa BII) and the other (kappa BI) proximal to its core promoter. Mutation of kappa BII substantially reduced the extent to which the iNOS promoter could be induced by IFS and interfered with augmented responsiveness of the promoter to LPS+IFN-gamma. Mutation of kappa BI had a quantitatively less dramatic negative effect on LPS responsiveness and this construct still showed augmented responsiveness to LPS+IFN-gamma. When both kappa B elements were mutated, inducibility by LPS and, in particular, by LPS+IFN-gamma was paradoxically restored, compared with the mutated kappa BII alone, suggesting cooperative interactions among the transcription factors that trans-activate the iNOS gene. In vivo footprint analysis showed that both kappa B elements were bound by protein complexes when macrophages were stimulated with LPS +/- IFN-gamma. Furthermore, kappa BI was bound even in untreated cells, suggesting that kappa B binding proteins might also have a negative influence on expression of the gene. Both kappa BI and kappa BII were bound by NF-kappa B/Rel proteins found in nuclear extracts prepared from macrophages treated with LPS + IFN-gamma, although the specificity of binding to each element was different. Our results show that, while NF-kappa B/Rel proteins are required for maximal expression of the iNOS gene, alone they are not alone sufficient. Furthermore, the results reported here show that the augmentative effect of IFN-gamma on the LPS- induced expression of the INOS gene is not mediated through increased activation of NF-kappa B/Rel. |
