Glycobiology Advance Access originally published online on June 29, 2007
Glycobiology 2007 17(9):1015-1028; doi:10.1093/glycob/cwm071
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C-Mannosylated peptides derived from the thrombospondin type 1 repeat enhance lipopolysaccharide-induced signaling in macrophage-like RAW264.7 cells
3 Department of Biochemistry and Molecular Biology in Disease, Atomic Bomb Disease Institute
4 Department of Dermatology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8523, Japan
5 CREST, JST Kawaguchi 332-1102, Kawaguchi, Japan
6 RIKEN, Saitama 351-0198, Japan
7 Department of Biochemistry, Wakayama Medical University, Wakayama 641-8509, Japan
1 To whom correspondence should be addressed: Tel/Fax: +81-73-441-0628; e-mail: y-ihara{at}wakayama-med.ac.jp
Received on May 18, 2007; revised on June 20, 2007; accepted on June 24, 2007
C-Mannosylation is a unique type of glycosylation occuring at the first Trp (W) in the WXXW motif, which is found in the thrombospondin type 1 repeat (TSR) of proteins. However, the biological function of C-mannosylation is not fully understood. In this study, we investigated the effect of C-mannosylated TSR-derived peptides on lipopolysaccharide (LPS)-induced signaling in macrophage-like RAW264.7 cells. The cells were stimulated with LPS in the presence or absence of chemically synthesized peptides with or without C-mannose (e.g., (C-Man)-Trp-Ser-Pro-Trp [C-Man-WSPW], C-Man-W, WSPW, etc.), then the effects of the peptides on cellular viability and signaling were examined. We found a cytotoxic effect in the cells treated with LPS and C-Man-WSPW, but not in the cells solely treated with LPS or C-Man-WSPW. We also found that production of tumor necrosis factor-
(TNF-
) was upregulated more in response to LPS plus C-Man-WSPW, than in response to LPS plus WSPW or LPS alone. Among the LPS-induced signaling pathways that induce production of TNF-
, the activation of c-Jun N-terminal kinase (JNK) was greatly enhanced by LPS and C-Man-WSPW, and the production of TNF-
was suppressed by an inhibitor for JNK. Together, these results demonstrate a novel function of the C-mannosylated TSR-derived peptide motif, to promote LPS-induced JNK signaling, and this leads to an enhancement of cytotoxicity via the upregulation of TNF-
production.
Key words: C-mannosylation / lipopolysaccharide / macrophage / thrombospondin
2 These authors contributed equally to this work.