title: Overlapping and differential expression of BIG-2, BIG-1, TAG-1, and F3: four members of an axon-associated cell adhesion molecule subgroup of the immunoglobulin superfamily.
abstract: Axon-associated cell adhesion molecules (AxCAMs) play crucial roles in the formation, maintenance, and plasticity of functional neuronal networks. We report here a molecular cloning of a novel AxCAM, BIG-2. BIG-2 is a member of TAG-1/F3 subgroup of the immunoglobulin (Ig) superfamily, with six Ig-like domains, four fibronectin type III-like repeats, and a glycosyl phosphatidylinositol-anchoring domain. Recombinant BIG-2 protein had a neurite outgrowth-promoting activity when used as a substrate for neurons in vitro. To survey the spatial expression pattern of BIG-2 in comparison with other TAG-1/F3 subgroup members, an in situ hybridization analysis was performed in adult and developing rat brain sections with riboprobes specific for BIG-2, BIG-1, TAG-1, and F3. The four AxCAM transcripts displayed cell type-specific expression patterns with overlapping and distinct profiles. In adult hippocampus, for example, we observed BIG-1 mRNA specifically in granule cells of the dentate gyrus, BIG-2 mRNA highly in the CA1 pyramidal cells, TAG-1 mRNA predominantly in the CA3 pyramidal cells, and F3 mRNA in neurons in all of these fields. These results suggest that BIG-2, BIG-1, TAG-1, and F3 may play important roles in the formation and maintenance of specific neuronal networks in the brain.
authors.affiliation: Department of Neuroscience, Osaka Bioscience Institute, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshihara
authors.forename: M
authors.initials: M
authors.lastname: Kawasaki
authors.forename: A
authors.initials: A
authors.lastname: Tamada
authors.forename: S
authors.initials: S
authors.lastname: Nagata
authors.forename: H
authors.initials: H
authors.lastname: Kagamiyama
authors.forename: K
authors.initials: K
authors.lastname: Mori
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000737:chemistry*; D015152:Blotting, Northern; D001921:Brain / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D015816:Cell Adhesion Molecules, Neuronal / Q000032:analysis* / Q000235:genetics; D003001:Cloning, Molecular; D058969:Contactin 2; D058966:Contactins; D018076:DNA, Complementary / Q000235:genetics; D007136:Immunoglobulins / Q000032:analysis*; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000235:genetics; D016501:Neurites / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; C548676:Cntn2 protein, rat; C088976:Cntn3 protein, rat; C484360:Cntn4 protein, rat; D058969:Contactin 2; D058966:Contactins; D018076:DNA, Complementary; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger