Nectin-1 spots as a novel adhesion apparatus that tethers mitral cell lateral dendrites in a dendritic meshwork structure of the developing mouse olfactory bulb

• Published in: Journal of comparative neurology (1911) 2015-08, Vol.523 (12), p.1824-1839
• Main Authors: Inoue, Takahito, Fujiwara, Takeshi, Rikitake, Yoshiyuki, Maruo, Tomohiko, Mandai, Kenji, Kimura, Kazushi, Kayahara, Tetsuro, Wang, Shujie, Itoh, Yu, Sai, Kousyoku, Mori, Masahiro, Mori, Kensaku, Mizoguchi, Akira, Takai, Yoshimi
• Format: Article
• Language: English
• Subjects: Animals; Biotin - analogs & derivatives; Cell Adhesion - physiology; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Dendrites - metabolism; Dendrites - ultrastructure; dendritic contacts; dendrodendritic reciprocal synapses; Dextrans; external plexiform layer (EPL); granule cells; Hippocampus - cytology; Hippocampus - growth & development; Hippocampus - metabolism; Imaging, Three-Dimensional; Immunoblotting; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Microscopy, Immunoelectron; mitral cell lateral dendrites; Nectins; Neurons - cytology; Neurons - metabolism; Olfactory Bulb - cytology; Olfactory Bulb - growth & development; Olfactory Bulb - metabolism; RRID: AB_2077527; RRID: AB_257881; RRID: AB_301787; RRID: AB_476737; RRID: AB_476831; RRID: AB_477617; RRID: nif-0000-00262; RRID: nif-0000-30467
• ISSN: 0021-9967; 1096-9861
• DOI: 10.1002/cne.23762

Mitral cells project lateral dendrites that contact the lateral and primary dendrites of other mitral cells and granule cell dendrites in the external plexiform layer (EPL) of the olfactory bulb. These dendritic structures are critical for odor information processing, but it remains unknown how they are formed. In immunofluorescence microscopy, the immunofluorescence signal for the cell adhesion molecule nectin‐1 was concentrated on mitral cell lateral dendrites in the EPL of the developing mouse olfactory bulb. In electron microscopy, the immunogold particles for nectin‐1 were symmetrically localized on the plasma membranes at the contacts between mitral cell lateral dendrites, which showed bilateral darkening without dense cytoskeletal undercoats characteristic of puncta adherentia junctions. We named the contacts where the immunogold particles for nectin‐1 were symmetrically accumulated "nectin‐1 spots." The nectin‐1 spots were 0.21 μm in length on average and the distance between the plasma membranes was 20.8 nm on average. In 3D reconstruction of serial sections, clusters of the nectin‐1 spots formed a disc‐like structure. In the mitral cell lateral dendrites of nectin‐1‐knockout mice, the immunogold particles for nectin‐1 were undetectable and the plasma membrane darkening was electron‐microscopically normalized, but the plasma membranes were partly separated from each other. The nectin‐1 spots were further identified between mitral cell lateral and primary dendrites and between mitral cell lateral dendrites and granule cell dendritic spine necks. These results indicate that the nectin‐1 spots constitute a novel adhesion apparatus that tethers mitral cell dendrites in a dendritic meshwork structure of the developing mouse olfactory bulb. J. Comp. Neurol. 523:1824–1839, 2015. © 2015 Wiley Periodicals, Inc. Using immunofluorescence microscopy and electron microscopy, the authors show that the immunoglobulin‐like cell adhesion molecule nectin‐1 is symmetrically localized at the contacts between mitral cell lateral dendrites in the external plexiform layer of the developing mouse olfactory bulb. Nectin‐1 forms a novel adhesion apparatus, named nectin‐1 spots, at the contacts.