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Elife. 2019 Feb 26;8. pii: e44552. doi: 10.7554/eLife.44552.

Aurora A depletion reveals centrosome-independent polarization mechanism in Caenorhabditis elegans.

Author information

1
Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
2
Department of Biochemistry, University of Geneva, Geneva, Switzerland.
3
Department of Theoretical Physics, University of Geneva, Geneva, Switzerland.
4
BIOTEC, TU Dresden, Dresden, Germany.
5
Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
6
Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany.
7
National Center of Competence in Research Chemical Biology, University of Geneva, Geneva, Switzerland.

Abstract

How living systems break symmetry in an organized manner is a fundamental question in biology. In wild-type Caenorhabditis elegans zygotes, symmetry breaking during anterior-posterior axis specification is guided by centrosomes, resulting in anterior-directed cortical flows and a single posterior PAR-2 domain. We uncover that C. elegans zygotes depleted of the Aurora A kinase AIR-1 or lacking centrosomes entirely usually establish two posterior PAR-2 domains, one at each pole. We demonstrate that AIR-1 prevents symmetry breaking early in the cell cycle, whereas centrosomal AIR-1 instructs polarity initiation thereafter. Using triangular microfabricated chambers, we establish that bipolarity of air-1(RNAi) embryos occurs effectively in a cell-shape and curvature-dependent manner. Furthermore, we develop an integrated physical description of symmetry breaking, wherein local PAR-2-dependent weakening of the actin cortex, together with mutual inhibition of anterior and posterior PAR proteins, provides a mechanism for spontaneous symmetry breaking without centrosomes.

KEYWORDS:

Aurora A; C. elegans; anterior-posterior polarity; cell biology; physical analysis; symmetry breaking

PMID:
30801250
DOI:
10.7554/eLife.44552
Free PMC Article

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