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Infection and Immunity, January 2007, p. 164-174, Vol. 75, No. 1
0019-9567/07/$08.00+0 doi:10.1128/IAI.01239-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Department of Bacteriology,1 Radioisotope Institute for Basic and Clinical Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan2
Received 4 August 2006/ Returned for modification 14 September 2006/ Accepted 2 October 2006
The Serratia marcescens-derived protease serralysin is considered
to play an important role in the pathogenesis of infection.
Protease-activated receptor 2 (PAR-2) is activated by trypsin and also
several other trypsin-like serine proteases, leading to the modulation
of inflammatory and immune responses. However, little is known about
the activation of PAR-2 by bacterial proteases and its roles in
bacterial infection. In this study, we investigated whether S.
marcescens serralysin activates host inflammatory responses
through PAR-2. Our results demonstrated that serralysin induces
interleukin-6 (IL-6) and IL-8 mRNA expression in a human lung squamous
cell carcinoma, EBC-l cells. In addition, serralysin activated
activator protein 1 (AP-1)-, CCAAT/enhancer-binding protein (C/EBP)-,
and nuclear factor-
B (NF-
B)-driven promoters in EBC-1
cells. An electrophoretic mobility shift assay showed that serralysin
activates the binding of AP-1, C/EBPß, and NF-
B in the
cells. Inactivation of serralysin resulted in the failure of
transactivation of AP-1-, C/EBP-, and NF-
B-driven promoters in
the cells. Furthermore, serralysin activated AP-1-, C/EBP-, and
NF-
B-driven promoters via PAR-2 in HeLa cells. PAR-2
antagonist peptides decreased serralysin-induced transactivation of
AP-1-, C/EBP-, and NF-
B-driven promoters in EBC-1 cells.
Considered together, these results suggest that serralysin requires
PAR-2 to activate the critical transcription factors AP-1,
C/EBPß, and NF-
B for host inflammatory
responses.
Published ahead of print on 16 October 2006.
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