Glycobiology Advance Access published online on March 2, 2009
Glycobiology, doi:10.1093/glycob/cwp031
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Specific Inhibition of FGF-2 Signaling with 2-O-sulfated Octasaccharides of Heparan Sulfate
Institute for Molecular Science of Medicine
* Research Complex for the Medicine Frontiers, Aichi Medical University, Yazako, Nagakute, Aichi 480–1195, Japan
Corresponding author: Koji Kimata, Institute for Molecular Science of Medicine and Research Complex for the Medicine Frontiers, Aichi Medical University, Yazako, Nagakute, Aichi 480–1195, Japan, Phonr: +81–561-61–1898, Fax: +81–561-61–1896, E-mail: kimata{at}aichi-med-u.ac.jp
Received on June 11, 2008; accepted on February 23, 2009
In fibroblast growth factor (FGF)-2 signaling, the formation of a ternary complex of FGF-2, tyrosine-kinase fibroblast growth factor receptor (FGFR)-1, and cell surface heparan sulfate (HS) proteoglycan is known to be critical for the activation of FGFR-1 and down stream signal transduction. Exogenous heparin polymer and some octasaccharides inhibited FGF-2-induced phosphorylation both of FGFR-1 and of extracellular signal-regulated kinase (ERK1/2) in Chinese hamster ovary (CHO)-K1 cells transfected with FGFR-1, which present HS on their cell surface. The inhibitory effect of octasaccharide was dependent on the number of 2-O-sulfate groups within a molecule but independent of the number of 6-O-sulfate groups. Sulfation at the 2-O-position was a prerequisite not only for binding of HS to FGF-2 but also for regulation of FGF-2 signaling and competitive inhibition with endogenous HS. Interestingly, FGF-4-induced phosphorylation was impeded only by specific octasaccharides containing both 2-O- and 6-O-sulfated groups, which were necessary for binding FGF-4. In CHO-677 cells deficient in HS biosynthesis, heparin enhanced FGF-2-induced phosphorylation of ERK1/2. On the other hand, a FGF-2-binding octasaccharide inhibited the phosphorylation. Our data suggest that the activity of particular heparin-binding factors can be inhibited by distinctive oligosaccharides that can bind the factors but cannot form functional signaling complexes irrespective of whether cells have a normal complement of HS or lack HS.
Key words: fibroblast growth factor / fibroblast growth factor receptor / heparan sulfate / oligo-saccharide / phosphorylation