Transcriptional regulation of the human iNOS gene in vascular-smooth-muscle cells and macrophages: Evidence for tissue specificity

We have cloned the 5' upstream -1034 to +88 fragment of the human inducible nitric oxide synthase (hiNOS) gene and demonstrate its competence to promote luciferase gene transcription in vascular-smooth-muscle (VSM) cells and macrophages. Sequential 5' end-deletions localized positive regulatory elements of hiNOS transcription in VSM A7r5 cells downstream of nucleotide -205 and demonstrated the functional importance of the resident NF-kappa B site (nucleotides -115 to -106). The hiNOS promoter/enhancer was induced strongly by LPS and IFN-gamma, and modestly by IL-1 beta in RAW 264.7 cells, but not in VSM cells. Truncation of the NF-kappa B site markedly diminished, but did not eliminate, LPS-inducibility. Sodium salicylate and ibuprofen down-regulated the basal transcriptional activity of the hiNOS promoter/enhancer in VSM but not in RAW 264.7 cells. These results indicate that the transcriptional regulation of the hiNOS gene features considerable complexity and tissue specificity. (C) 1996 Academic Press, Inc.