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Up‐regulation of human iNOS transcription by p300 and AP‐1 interaction
Author(s) -
Guo Zhong,
Shao Lifang,
Geller David A
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.495.15
Subject(s) - transactivation , enhancer , coactivator , microbiology and biotechnology , enhancer rnas , transcription factor , transcription (linguistics) , promoter , biology , cytokine , binding site , gene expression , chemistry , gene , genetics , linguistics , philosophy
p300, a ubiquitous transcription coactivator, plays an important role in gene activation. Our previous work demonstrated that human iNOS (hiNOS) expression can be highly induced with the cytokine mixture (CM) of TNFα + IL‐1β + IFNγ. In this study, we investigated the functional role of p300 in the regulation of hiNOS gene expression. Our initial data showed that overexpression of p300 significantly increased the basal and cytokine‐induced hiNOS promoter activities in A549 cells. Interestingly, p300 activated cytokine‐induced hiNOS transcriptional activity was completely abrogated by deleting the upstream hiNOS enhancer at ‐5 kb and ‐6 kb in the promoter. Furthermore, p300 over‐expression increased cytokine‐induced transcription activity on a heterologous minimal TK promoter with the same hiNOS enhancer. Site‐directed mutagenesis of the hiNOS AP‐1 motifs revealed that an intact upstream (‐5.3kb) AP‐1 binding site was critical for p300 mediated cytokine‐induced hiNOS transcription. Lastly, our ChIP analysis and gel shift assay proved that p300 was binding to Jun B proteins at ‐5.3 kb AP‐1 binding site in vivo and in vitro . Our results suggest that coactivator p300 mediates cytokine‐induced hiNOS transactivation.