title: Nepmucin, a novel HEV sialomucin, mediates L-selectin-dependent lymphocyte rolling and promotes lymphocyte adhesion under flow.
abstract: Lymphocyte trafficking to lymph nodes (LNs) is initiated by the interaction between lymphocyte L-selectin and certain sialomucins, collectively termed peripheral node addressin (PNAd), carrying specific carbohydrates expressed by LN high endothelial venules (HEVs). Here, we identified a novel HEV-associated sialomucin, nepmucin (mucin not expressed in Peyer's patches [PPs]), that is expressed in LN HEVs but not detectable in PP HEVs at the protein level. Unlike conventional sialomucins, nepmucin contains a single V-type immunoglobulin (Ig) domain and a mucin-like domain. Using materials affinity-purified from LN lysates with soluble L-selectin, we found that two higher molecular weight species of nepmucin (75 and 95 kD) were decorated with oligosaccharides that bind L-selectin as well as an HEV-specific MECA-79 monoclonal antibody. Electron microscopic analysis showed that nepmucin accumulates in the extended luminal microvillus processes of LN HEVs. Upon appropriate glycosylation, nepmucin supported lymphocyte rolling via its mucin-like domain under physiological flow conditions. Furthermore, unlike most other sialomucins, nepmucin bound lymphocytes via its Ig domain, apparently independently of lymphocyte function-associated antigen 1 and very late antigen 4, and promoted shear-resistant lymphocyte binding in combination with intercellular adhesion molecule 1. Collectively, these results suggest that nepmucin may serve as a dual-functioning PNAd in LN HEVs, mediating both lymphocyte rolling and binding via different functional domains.
authors.affiliation: Laboratory of Immunodynamics, Department of Microbiology and Immunology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Umemoto
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Tanaka
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Kanda
authors.forename: Soojung
authors.initials: S
authors.lastname: Jin
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tohya
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Otani
authors.forename: Takahiro
authors.initials: T
authors.lastname: Matsutani
authors.forename: Masanori
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Ebisuno
authors.forename: Myoung Ho
authors.initials: MH
authors.lastname: Jang
authors.forename: Minoru
authors.initials: M
authors.lastname: Fukuda
authors.forename: Takako
authors.initials: T
authors.lastname: Hirata
authors.forename: Masayuki
authors.initials: M
authors.lastname: Miyasaka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion; D018076:DNA, Complementary / Q000235:genetics; D004730:Endothelium, Vascular / Q000502:physiology; D006801:Humans; D019041:L-Selectin / Q000502:physiology*; D008214:Lymphocytes / Q000382:microbiology / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D010581:Peyer's Patches / Q000276:immunology / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D052116:Sialomucins / Q000235:genetics / Q000502:physiology*; D014699:Venules / Q000502:physiology
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D052116:Sialomucins; C512481:nepmucin, mouse; D019041:L-Selectin