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Glycobiology Advance Access published online on June 29, 2007
Glycobiology, doi:10.1093/glycob/cwm071
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© The Author 2007. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org

C-Mannosylated peptides derived from the thrombospondin type 1 repeat enhance lipopolysaccharide-induced signaling in macrophage-like RAW264.7 cells

Eiji Muroi1,2,3,*, Shino Manabe3,4, Midori Ikezaki1,3, Yoshishige Urata1, Shinichi Sato2, Takahito Kondo1, Yukishige Ito3,4 and Yoshito Ihara1,3,5,*

1 Department of Biochemistry and Molecular Biology in Disease, Atomic Bomb Disease Institute
2 Department of Dermatology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8523
3 CREST, JST Kawaguchi 332-1102
4 RIKEN, Saitama 351-0198
5 Department of Biochemistry, Wakayama Medical University, Wakayama 641-8509, Japan

Address correspondence to: Yoshito Ihara, Department of Biochemistry and Molecular Biology in Disease, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan, Phone: 81-95-849-7099; Fax: 81-95-849-7100; E-mail: y-ihara{at}net.nagasaki-u.ac.jp

Received on May 18, 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-{alpha} (TNF-{alpha}) was up-regulated 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-{alpha}, the activation of c-Jun N-terminal kinase (JNK) was greatly enhanced by LPS and C-Man-WSPW, and the production of TNF-{alpha} 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-{alpha} production.

Key words: C-mannosylation / Thrombospondin / Macrophage / Lipopolysaccharide

* Both authors contributed equally to this work.


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