title: KSGal6ST generates galactose-6-O-sulfate in high endothelial venules but does not contribute to L-selectin-dependent lymphocyte homing.
abstract: The addition of sulfate to glycan structures can regulate their ability to serve as ligands for glycan-binding proteins. Although sulfate groups present on the monosaccharides glucosamine, uronate, N-acetylglucosamine and N-acetylgalactosamine are recognized by defined receptors that mediate important functions, the functional significance of galactose-6-O-sulfate (Gal6S) is not known. However, in vitro studies using synthetic glycans and sulfotransferase overexpression implicate Gal6S as a binding determinant for the lymphocyte homing receptor, L-selectin. Only two sulfotransferases have been shown to generate Gal6S, namely keratan sulfate galactose 6-O-sulfotransferase (KSGal6ST) and chondroitin 6-O-sulfotransferase-1 (C6ST-1). In the present study, we use mice deficient in KSGal6ST and C6ST-1 to test whether Gal6S contributes to ligand recognition by L-selectin in vivo. First, we establish that KSGal6ST is selectively expressed in high endothelial venules (HEVs) in lymph nodes and Peyer's patches. We also determine by mass spectrometry that KSGal6ST generates Gal6S on several classes of O-glycans in peripheral lymph nodes. Furthermore, KSGal6ST, but not C6ST-1, is required for the generation of the Gal6S-containing glycan, 6,6'-disulfo-3'sLN (Siaα2→3[6S]Galβ1→4[6S]GlcNAc) or a closely related structure in lymph node HEVs. Nevertheless, L-selectin-dependent short-term homing of lymphocytes is normal in KSGal6ST-deficient mice, indicating that the Gal6S-containing structures we detected do not contribute to L-selectin ligand recognition in this setting. These results refine our understanding of the biological ligands for L-selectin and introduce a mouse model for investigating the functions of Gal6S in other contexts.
authors.affiliation: Department of Anatomy and Program in Biomedical Sciences,  University of California, San Francisco, CA 94143-0452,  USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Patnode
authors.forename: Shin-Yi
authors.initials: SY
authors.lastname: Yu
authors.forename: Chu-Wen
authors.initials: CW
authors.lastname: Cheng
authors.forename: Ming-Yi
authors.initials: MY
authors.lastname: Ho
authors.forename: Lotten
authors.initials: L
authors.lastname: Tegesjö
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Sakuma
authors.forename: Kenji
authors.initials: K
authors.lastname: Uchimura
authors.forename: Kay-Hooi
authors.initials: KH
authors.lastname: Khoo
authors.forename: Reiji
authors.initials: R
authors.lastname: Kannagi
authors.forename: Steven D
authors.initials: SD
authors.lastname: Rosen
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000502:physiology; D005690:Galactose / Q000031:analogs & derivatives* / Q000378:metabolism; D019041:L-Selectin / Q000378:metabolism*; D008198:Lymph Nodes / Q000378:metabolism; D042601:Lymphatic Vessels / Q000378:metabolism* / Q000502:physiology; D008214:Lymphocytes / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D015238:Sulfotransferases / Q000235:genetics / Q000378:metabolism*; D000097811:Carbohydrate Sulfotransferases
chemical_list: D005690:Galactose; D019041:L-Selectin; D015238:Sulfotransferases; D000097811:Carbohydrate Sulfotransferases; C086947:galactose 6-sulfate