title: CAMSAP3 orients the apical-to-basal polarity of microtubule arrays in epithelial cells.
abstract: Polarized epithelial cells exhibit a characteristic array of microtubules that are oriented along the apicobasal axis of the cells. The minus-ends of these microtubules face apically, and the plus-ends face toward the basal side. The mechanisms underlying this epithelial-specific microtubule assembly remain unresolved, however. Here, using mouse intestinal cells and human Caco-2 cells, we show that the microtubule minus-end binding protein CAMSAP3 (calmodulin-regulated-spectrin-associated protein 3) plays a pivotal role in orienting the apical-to-basal polarity of microtubules in epithelial cells. In these cells, CAMSAP3 accumulated at the apical cortices, and tethered the longitudinal microtubules to these sites. Camsap3 mutation or depletion resulted in a random orientation of these microtubules; concomitantly, the stereotypic positioning of the nucleus and Golgi apparatus was perturbed. In contrast, the integrity of the plasma membrane was hardly affected, although its structural stability was decreased. Further analysis revealed that the CC1 domain of CAMSAP3 is crucial for its apical localization, and that forced mislocalization of CAMSAP3 disturbs the epithelial architecture. These findings demonstrate that apically localized CAMSAP3 determines the proper orientation of microtubules, and in turn that of organelles, in mature mammalian epithelial cells.
authors.affiliation: Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan;
authors.forename: Mika
authors.initials: M
authors.lastname: Toya
authors.affiliation: Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan;
authors.forename: Saeko
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan;
authors.forename: Miwa
authors.initials: M
authors.lastname: Kawasaki
authors.affiliation: Genetic Engineering Team, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan;
authors.forename: Go
authors.initials: G
authors.lastname: Shioi
authors.affiliation: Animal Resource Development Unit, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan;
authors.forename: Mari
authors.initials: M
authors.lastname: Kaneko
authors.affiliation: Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan;
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishiuchi
authors.affiliation: Ultrastructural Research Team, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Misaki
authors.affiliation: Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan;
authors.forename: Wenxiang
authors.initials: W
authors.lastname: Meng
authors.affiliation: Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan; takeichi@cdb.riken.jp.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Takeichi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D018938:Caco-2 Cells; D016764:Cell Polarity; D020895:Enterocytes / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006720:Homozygote; D006801:Humans; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D015739:Nocodazole / Q000494:pharmacology; D015388:Organelles / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013347:Subcellular Fractions / Q000378:metabolism; D053778:Thiazolidines / Q000494:pharmacology
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; C000608274:Camsap3 protein, human; C578015:Camsap3 protein, mouse; D008869:Microtubule-Associated Proteins; D053778:Thiazolidines; D049452:Green Fluorescent Proteins; D015739:Nocodazole; C037067:latrunculin A
keywords: CAMSAP; Nezha; intestinal epithelial cell; microtubule assembly; microtubule minus-end