title: The variable transmembrane domain of Drosophila N-cadherin regulates adhesive activity.
abstract: Drosophila N-cadherin (CadN) is an evolutionarily conserved classic cadherin which has a large, complex extracellular domain and a catenin-binding cytoplasmic domain. The CadN locus contains three modules of alternative exons (7a/b, 13a/b, and 18a/b) and undergoes alternative splicing to generate multiple isoforms. Using quantitative transcript analyses and green fluorescent protein-based cell sorting, we found that during development CadN alternative splicing is regulated in a temporal but not cell-type-specific fashion. In particular, exon 18b is predominantly expressed during early developmental stages, while exon 18a is prevalent at the late developmental and adult stages. All CadN isoforms share the same molecular architecture but have different sequences in their extracellular and transmembrane domains, suggesting functional diversity. In vitro quantitative cell aggregation assays revealed that all CadN isoforms mediate homophilic interactions, but the isoforms encoded by exon 18b have a higher adhesive activity than those by its alternative, 18a. Domain-swapping experiments further revealed that the different sequences in the transmembrane domains of isoforms are responsible for their differential adhesive activities. CadN alternative splicing might provide a novel mechanism to fine-tune its adhesive activity at different developmental stages or to restrict the use of high-affinity 18b-type isoforms at the adult stage.
authors.affiliation: Unit of Neuronal Connectivity, Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, National Institutes of Health, Building 18T, Room 106, MSC 5431, Bethesda, MD 20892, USA.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yonekura
authors.forename: Chun-Yuan
authors.initials: CY
authors.lastname: Ting
authors.forename: Guilherme
authors.initials: G
authors.lastname: Neves
authors.forename: Kimberly
authors.initials: K
authors.lastname: Hung
authors.forename: Shu-Ning
authors.initials: SN
authors.lastname: Hsu
authors.forename: Akira
authors.initials: A
authors.lastname: Chiba
authors.forename: Andrew
authors.initials: A
authors.lastname: Chess
authors.forename: Chi-Hon
authors.initials: CH
authors.lastname: Lee
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D015820:Cadherins / Q000737:chemistry / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002449:Cell Aggregation; D002462:Cell Membrane / Q000737:chemistry*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000378:metabolism*; D005091:Exons / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D049750:Genome, Insect / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D015820:Cadherins; D020033:Protein Isoforms; D012333:RNA, Messenger; D002118:Calcium