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Conditional expression of liver‐enriched transcriptional activator protein augments Acholeplasma laidlawii ‐induced granulysin gene expression in a human monocytic cell line, THP‐1
Author(s) -
Kida Yutaka,
Shimizu Takashi,
Kuwano Koichi
Publication year - 2005
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1111/j.1365-2567.2004.02069.x
Subject(s) - granulysin , biology , activator (genetics) , gene expression , microbiology and biotechnology , thp1 cell line , gene knockdown , regulation of gene expression , gene , ccaat enhancer binding proteins , cell culture , transcription factor , nuclear protein , in vitro , biochemistry , cytotoxicity , genetics , perforin
Summary The antimicrobial protein granulysin is considered to play an important role in the defence mechanism against bacterial infection. We previously reported that Acholeplasma laidlawii ‐induced transactivation of the granulysin promoter in a human monocytic cell line, THP‐1, is regulated by activator protein‐1 and CCAAT/enhancer binding protein‐β (C/EBPβ), but not by nuclear factor‐κB. Moreover, liver‐enriched transcriptional inhibitory protein (LIP), a C/EBPβ isoform, was strongly induced in A. laidlawii ‐stimulated THP‐1 cells. However, the level of liver‐enriched transcriptional activator protein (LAP), another C/EBPβ isoform, was essentially constant. Accordingly, we speculated that LIP would down‐regulate A. laidlawii ‐induced granulysin gene expression in THP‐1 cells. In the present study, we examined whether LAP augments A. laidlawii ‐induced granulysin gene expression using conditional LAP‐expressing THP‐1 cells in a tetracycline‐controlled expression system. Our results indicated that conditional expression of LAP augmented A. laidlawii ‐induced expression of granulysin mRNA. In addition, the granulysin protein was observed in A. laidlawii ‐stimulated, LAP‐expressing THP‐1 cells. Our results suggest that the expression of LAP plays a critical role in the expression of the granulysin gene in macrophages.