Conditional expression of liver-enriched transcriptional activator protein augments Acholeplasma laidlawii-induced granulysin gene expression in a human monocytic cell line, THP-1.
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-beta (C/EBPbeta), but not by nuclear factor-kappaB. Moreover, liver-enriched transcriptional inhibitory protein (LIP), a C/EBPbeta isoform, was strongly induced in A. laidlawii-stimulated THP-1 cells. However, the level of liver-enriched transcriptional activator protein (LAP), another C/EBPbeta 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.
Kida
Yutaka
Y
Department of Bacteriology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan.
Shimizu
Takashi
T
Kuwano
Koichi
K
D000128:Acholeplasma laidlawii / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008099:Liver; D009000:Monocytes / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013752:Tetracycline / Q000494:pharmacology; D015533:Transcriptional Activation / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D022782:CCAAT-Enhancer-Binding Protein-beta; C075005:GNLY protein, human; D012333:RNA, Messenger; D013752:Tetracycline