title: ADIP, a novel Afadin- and alpha-actinin-binding protein localized at cell-cell adherens junctions.
abstract: Afadin is an actin filament (F-actin)-binding protein that is associated with the cytoplasmic tail of nectin, a Ca(2+)-independent immunoglobulin-like cell-cell adhesion molecule. Nectin and afadin strictly localize at cell-cell adherens junctions (AJs) undercoated with F-actin bundles and are involved in the formation of AJs in cooperation with E-cadherin in epithelial cells. In epithelial cells of afadin (-/-) mice and (-/-) embryoid bodies, the proper organization of AJs is markedly impaired. However, the molecular mechanism of how the nectin-afadin system is associated with the E-cadherin-catenin system or functions in the formation of AJs has not yet been fully understood. Here we identified a novel afadin-binding protein, named ADIP (afadin DIL domain-interacting protein). ADIP consists of 615 amino acids with a calculated M(r) of 70,954 and has three coiled-coil domains. Northern and Western blot analyses in mouse tissues indicated that ADIP was widely distributed. Immunofluorescence and immunoelectron microscopy revealed that ADIP strictly localized at cell-cell AJs undercoated with F-actin bundles in small intestine absorptive epithelial cells. This localization pattern was the same as those of afadin and nectin. ADIP was undetectable at cell-matrix AJs. ADIP furthermore bound alpha-actinin, an F-actin-bundling protein known to be indirectly associated with E-cadherin through its direct binding to alpha-catenin. These results indicate that ADIP is an afadin- and alpha-actinin-binding protein that localizes at cell-cell AJs and may have two functions. ADIP may connect the nectin-afadin and E-cadherin-catenin systems through alpha-actinin, and ADIP may be involved in organization of the actin cytoskeleton at AJs through afadin and alpha-actinin.
authors.affiliation: Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/ Faculty of Medicine, Suita 565-0871, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Asada
authors.forename: Kenji
authors.initials: K
authors.lastname: Irie
authors.forename: Koji
authors.initials: K
authors.lastname: Morimoto
authors.forename: Akio
authors.initials: A
authors.lastname: Yamada
authors.forename: Wataru
authors.initials: W
authors.lastname: Ikeda
authors.forename: Masakazu
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Takai
mesh_terms: D000185:Actinin / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D022005:Adherens Junctions / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D017931:DNA Primers; D004285:Dogs; D006801:Humans; D016547:Kinesins; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D008869:Microtubule-Associated Proteins; D008969:Molecular Sequence Data; D009218:Myosins; D011233:Precipitin Tests; D011485:Protein Binding; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: C095516:AFDN protein, human; D048868:Adaptor Proteins, Signal Transducing; C490657:Afdn protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D017931:DNA Primers; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; C472295:Ssx2ip protein, mouse; C472296:Ssx2ip protein, rat; C108835:afadin; D000185:Actinin; D009218:Myosins; D016547:Kinesins