NO production in RASM stimulated with interleukin-l (IL-1β) involves the activation of nuclear factor-K (NF-KB} (Mülsch et al. Faseh J 9: A556.1995). Previously we reported the induction of NO synlhase ( iNOS ) and NO production by the protein synthesis inhibitor cycloheximide (CH), independently of other known inducers. Moreover. CH caused a laic-onset superinduction of lipopolysaccharide (LPS)-stimulated iNOS activity. These findings suggest the involvement of a CH-sensitive inhibitor in the activation of NOS. We hypothesized that protein synthesis inhibition by CH reduces levels of 1KB, a labile inhibitor of NF-KB. leading to NF KB activation and subsequent iNOS gene expression. Western blot analysis of RASM treated with lOuM CH and I0ng/ml LPS for 24hrs revealed elevated iNOS protein levels. In addition, CH caused a lime dependent decline in 1KB protein levels and a concommitant rise of a slower migrating isolbmi. Both the increase in iNOS activity and decline in 1KB protein levels by CH were significantly reduced by various protease inhibitors. Electrophoretic mobility shift assays confirmed that CH alone activated NFKB and augmented LPS-activaled NpKB. These results provide evidence that reduction in licBa basal levels leads to increased NF-KB-mediated iNOS gene expression and enzyme activity. (Supponed by HI, 52458L.
|Original language||English (US)|
|Publication status||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology