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Proc Natl Acad Sci U S A. 2016 Jan 12;113(2):332-7. doi: 10.1073/pnas.1520638113. Epub 2015 Dec 29.

CAMSAP3 orients the apical-to-basal polarity of microtubule arrays in epithelial cells.

Author information

1
Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan;
2
Genetic Engineering Team, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan;
3
Animal Resource Development Unit, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan;
4
Ultrastructural Research Team, RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan.
5
Laboratory for Cell Adhesion and Tissue Patterning, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan; takeichi@cdb.riken.jp.

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.

KEYWORDS:

CAMSAP; Nezha; intestinal epithelial cell; microtubule assembly; microtubule minus-end

PMID:
26715742
PMCID:
PMC4720291
DOI:
10.1073/pnas.1520638113
[Indexed for MEDLINE]
Free PMC Article

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