Upregulation of ICAM-1 expression on J774.2 macrophages by endotoxin involves activation of NF-kappa B but not protein tyrosine kinase: comparison toinduction of iNOS

THIS study compares the signal transduction pathway which leads to the upre gulation of intercellular adhesion molecule-1 (ICAM-1) expression with that of the increase in the expression of inducible nitric oxide synthase (iNOS ) protein. and activity caused by endotoxin in cultured J774.2 macrophages, Treatment of J774.2 cells with Lipopolysaccharide E. coli (LPS) induced a concentration-dependent increase in the expression of ICAM-1 on the cell su rface within 4h and an increase in iNOS protein and activity at 24h. The up regulation of ICAM-1 expression on J774.2 macrophages caused by LPS was sig nificantly inhibited by pretreatment of the cells with inhibitors of the ac tivation of the nuclear transcription factor NF-kappa B, such as L-1-tosyla mido-2-phenylethylchloromethyl ketone (TPCK), pyrrolidine dithiocarbamate ( PDTC), rotenone or calpain inhibitor I, but not by the tyrosine kinase inhi bitors, tyrphostin AG126 or genistein. In contrast, genistein or tyrphostin AG126 also prevented the induction of iNOS protein and activity in J774.2 macrophages elicited by LPS. Thus, the increase in the expression of ICAM-1 on J774.2 macrophages by endotoxin involves the activation of NF kappa B, but not of protein tyrosine kinase.