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An interferon‐sensitive response element is involved in constitutive caspase‐8 gene expression in neuroblastoma cells
Author(s) -
De Ambrosis Alessandro,
Casciano Ida,
Croce Michela,
Pagnan Gabriella,
Radic Luana,
Banelli Barbara,
Di Vinci Angela,
Allemanni Giorgio,
Tonini Gian Paolo,
Ponzoni Mirco,
Romani Massimo,
Ferrini Silvano
Publication year - 2006
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.22173
Subject(s) - microbiology and biotechnology , chromatin immunoprecipitation , response element , biology , promoter , transcription (linguistics) , interferon stimulated gene , gene expression , gene , genetics , receptor , linguistics , philosophy , innate immune system
We previously identified a 1.2 Kb DNA element (P‐1161/+16), 5′ to caspase‐8 exon‐1, that acts as promoter in caspase‐8‐positive, but not in caspase‐8‐negative neuroblastoma (NB) cells. The P‐1161/+16 DNA element regulates both constitutive and interferon IFN‐γ‐inducible caspase‐8 expression. Two GAS (IFN‐activated sequence, STAT‐1 binding site) and two ISRE (interferon sensitive response element, IRF binding site) were present in P‐1161/+16. Deletion studies indicated that elements essential for promoter activity in NB cells were present in a 167 bp region 5′ flanking exon‐1 (P‐151/+16), which contains an ISRE at position −32. The transcription initiation site was mapped by 5′ rapid amplification of cDNA end (RACE) at position −20 from caspase‐8 cDNA reference sequence. Disruption of the ISRE‐32 indicated that it is required for both constitutive and IFN‐γ‐inducible caspase‐8 expression. IRF‐1 and IRF‐2 transcription factors bind to the (−151/+16) DNA fragment in vitro . Chromatin immunoprecipitation (ChIP) assays showed that IRF‐1 and IRF‐2 bind to the DNA region at the 5′ of caspase‐8 gene in NB cells, which show constitutive expression but not in caspase‐8 negative cells. In these last cells, up‐regulation of caspase‐8 by IFN‐γ was associated to induction of IRF‐1 and IRF‐2 binding to caspase‐8 promoter and increased histone acetylation. Moreover, RNA interference experiments also supported the involvement of IRF‐1 and IRF‐2 in constitutive caspase‐8 expression in NB cells. © 2006 Wiley‐Liss, Inc.