title: Alteration of the N-glycome of bovine milk glycoproteins during early lactation.
abstract: Milk provides nutritional, immunological and developmental components for newborns. Whereas identification of such components has been performed by targeting proteins and free oligosaccharides, structural and functional analyses of the N-glycome of milk glycoproteins are scarce. In this study, we investigated, for the first time, the alterations of the bovine milk N-glycome during early lactation (1 day, 1, 2, 3 and 4 weeks postpartum), characterizing more than 80 N-glycans. The glycomic profile of colostrum on day 1 after calving differed substantially from that in other periods during early lactation. The proteins in colostrum obtained 1 day postpartum were more highly sialylated than milk samples obtained at other time points, and the N-glycolylneuraminic acid (Neu5Gc)/N-acetylneuraminic acid (Neu5Ac) ratio was significantly higher on day 1, showing a gradual decline with time. In order to dissect the N-glycome of colostrum, alterations of the N-glycosylation profile of major bovine milk proteins during the early lactation stage were elucidated, revealing that the alteration is largely attributable to qualitative and quantitative N-glycosylation changes of IgG, the major glycoprotein in colostrum. Furthermore, by preparing and analyzing IgGs in which the N-glycan structure and subtypes were well characterized, we found that the interaction between IgG and FcRn was not affected by the structure of the N-glycans attached to IgG. We also found that bovine FcRn binds IgG(2) better than IgG(1) , strongly suggesting that the role of FcRn in the bovine mammary gland is to recycle IgG(2) from the udder to blood, rather than to secrete IgG(1) into colostrum.
authors.affiliation: Laboratory of Advanced Chemical Biology, Graduate School of Advanced Life Science, Hokkaido University, Sapporo, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Takimori
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Shimaoka
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Furukawa
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yamashita
authors.forename: Maho
authors.initials: M
authors.lastname: Amano
authors.forename: Naoki
authors.initials: N
authors.lastname: Fujitani
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takegawa
authors.forename: Lennart
authors.initials: L
authors.lastname: Hammarström
authors.forename: Imre
authors.initials: I
authors.lastname: Kacskovics
authors.forename: Yasuro
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Nishimura
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D003126:Colostrum / Q000737:chemistry*; D005260:Female; D006023:Glycoproteins / Q000032:analysis*; D006031:Glycosylation; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007774:Lactation; D008892:Milk / Q000737:chemistry*; D011247:Pregnancy; D020033:Protein Isoforms / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D006023:Glycoproteins; D007074:Immunoglobulin G; D020033:Protein Isoforms