Ets-1 is involved in transcriptional regulation of the chick inducible nitric oxide synthase gene in embryonic ventricular myoctyes

In order to elucidate roles of Ets family of transcription factors in trans criptional activation of inducible nitric oxide synthase (iNOS) genes, we a nalyzed the chick iNOS gene expression in cultured chick embryonic ventricu lar myocytes (CEVM). Deletional analysis and site-directed mutagenesis demo nstrated that both the Ets/PEA3 site (-221 to -216 bp) and the kappaB site (-101 to -93 bp) of the 5'-flanking region of the chick iNOS gene were invo lved in the maximal activation of the lipopolysaccharide (LPS)-induced expr ession of the reporter (luciferase) gene, although the proximal kappaB site played the more essential role. Electrophoretic mobility shift assay revea led that LPS augmented the nuclear protein bindings to the Ets/PEA3 as well as kappaB motifs. Ets-1, one of the Ets proteins, was suggested to be boun d to the Ets/PEA3 oligonucleotide. By Northern blot analysis, LPS was shown to induce iNOS mRNA in CEVM, along with a preceding increase in the levels of c-ets-1 mRNA. Ets-1 may be involved in the iNOS gene transcription in C EVM, presumably through interacting with the NF-kappaB.