Salmonella enteritidis FliC (flagella filament protein) induces human beta-defensin-2 mRNA production by Caco-2 cells.
Antimicrobial peptides are crucial for host defense at mucosal surfaces. Bacterial factors responsible for induction of human beta-defensin-2 (hBD-2) mRNA expression in Caco-2 human carcinoma cells were determined. Salmonella enteritidis, Salmonella typhimurium, Salmonella typhi, Salmonella dublin, and culture supernatants of these strains induced hBD-2 mRNA expression in Caco-2 human carcinoma cells. Using luciferase as a reporter gene for a approximately 2.1-kilobase pair hBD-2 promoter, the hBD-2-inducing factor in culture supernatant of S. enteritidis was isolated. The supernatant factor was heat-stable and proteinase-sensitive. After purification by anion exchange and gel filtration chromatography, the hBD-2-inducing factor was identified as a 53-kDa monomeric protein with the amino-terminal sequence AQVINTNSLSLLTQNNLNK, which is identical to that of the flagella filament structural protein (FliC) of S. enteritidis. Consistent with this finding, the 53-kDa protein reacted with anti-FliC antibody, which prevented its induction of hBD-2 mRNA in Caco-2 cells. In agreement, the hBD-2-inducing activity in culture supernatant was completely neutralized by anti-FliC antibody. In gel retardation analyses, FliC increased binding of NF-kappaB (p65 homodimer) to hBD-2 gene promoter sequences. We conclude that S. enteritidis FliC induces hBD-2 expression in Caco-2 cells via NF-kappaB activation and thus plays an important role in up-regulation of the innate immune response.
Ogushi
K
K
Department of Bacteriology, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan.
Wada
A
A
Niidome
T
T
Mori
N
N
Oishi
K
K
Nagatake
T
T
Takahashi
A
A
Asakura
H
H
Makino
S
S
Hojo
H
H
Nakahara
Y
Y
Ohsaki
M
M
Hatakeyama
T
T
Aoyagi
H
H
Kurazono
H
H
Moss
J
J
Hirayama
T
T
D000595:Amino Acid Sequence; D015153:Blotting, Western; D018938:Caco-2 Cells; D002467:Cell Nucleus / Q000378:metabolism; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004926:Escherichia coli / Q000378:metabolism; D005408:Flagellin / Q000378:metabolism*; D017353:Gene Deletion; D006801:Humans; D007239:Infections / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012475:Salmonella / Q000737:chemistry; D012477:Salmonella enteritidis / Q000737:chemistry*; D014162:Transfection; D015854:Up-Regulation; D023083:beta-Defensins / Q000096:biosynthesis*
C106641:DEFB4A protein, human; D016328:NF-kappa B; D012333:RNA, Messenger; D011994:Recombinant Proteins; D023083:beta-Defensins; D005408:Flagellin; D008156:Luciferases