Glycobiology Advance Access published online on October 24, 2008
Glycobiology, doi:10.1093/glycob/cwn110
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The N-linked oligosaccharide at Fc
RIIIa Asn-45: an inhibitory element for high FcRIIIa binding affinity to IgG glycoforms lacking core fucosylation
1 Tokyo Research Laboratories, Kyowa Hakko Kogyo Co., Ltd., 3–6-6 Asahi-machi, Machida-shi, Tokyo 194–8533, Japan
2 Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya 467–8603, Japan
Corresponding Author (to whom proofs and reprints should be addressed): Mitsuo Satoh; Phone: 81–42-725–2556; Fax: 81–42-726–8330; E-mail: msatoh{at}kyowa.co.jp
Received on August 22, 2008; accepted on October 10, 2008
Human leukocyte receptor IIIa (Fc
RIIIa) plays an important role in mediating therapeutic antibodies’ antibody-dependent cellular cytotoxicity (ADCC), which is closely related to the clinical efficacy of anticancer processes in humans in vivo. Removal of the core fucose from oligosaccharides attached to the Fc region of antibodies improves FcRIIIa binding, allowing the antibodies to enhance dramatically the antibody effector functions of ADCC. In this study, the contribution of FcRIIIa oligosaccharides to the strength of the FcRIIIa/antibody complex was analyzed using a serial set of soluble human recombinant FcRIIIa lacking the oligosaccharides. Nonfucosylated antibody IgG1 appeared to have a significantly higher affinity to the wild-type FcRIIIa fully glycosylated at its five N-linked oligosaccharide sites than did the fucosylated IgG1, and this increased binding was almost abolished once all of the FcRIIIa glycosylation was removed. Our gain-of-function analysis in the FcRIIIa oligosaccharide at Asn-162 (N-162) confirmed that N-162 is the element required for the high binding affinity to nonfucosylated antibodies, as previously revealed by loss-of-function analyses. Interestingly, beyond our expectation, the FcRIIIa modified by N-162 alone showed a significantly higher binding affinity to nonfucosylated IgG1 than did the wild-type FcRIIIa. Attachment of the other four oligosaccharides, especially the FcRIIIa oligosaccharide at Asn-45 (N-45), hindered the high binding affinity of FcRIIIa to nonfucosylated IgG1. Our data clearly demonstrated that N-45 is an inhibitory element for the high FcRIIIa binding affinity mediated by N-162 to nonfucosylated antibodies. This information can be exploited for the structural-based functional study of FcRIIIa.
Key words:
FcRIIIa binding affinity
/
IgG1 lacking core fucosylation
/
N-linked Fc oligosaccharides
/
N-linked FcRIIIa oligosaccharides
/
FcRIIIa Asn-45
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  P. Hossler, S. F Khattak, and Z. J. Li Optimal and consistent protein glycosylation in mammalian cell culture Glycobiology, September 1, 2009; 19(9): 936 - 949. [Abstract] [Full Text] [PDF]
|
|