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Genetics. 2017 Jun;206(2):873-888. doi: 10.1534/genetics.117.200766. Epub 2017 Apr 16.

The Hippo Pathway Maintains the Equatorial Division Plane in the Ciliate Tetrahymena.

Author information

1
Department of Cellular Biology, University of Georgia, Athens, Georgia 30602.
2
Bio3/Bioinformatics and Molecular Genetics (Faculty of Biology) and ZMBZ (Faculty of Medicine).
3
Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University of Freiburg, 79104 Germany.
4
Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, New York 10032.
5
Laboratory of Cytoskeleton and Cilia Biology, Department of Cell Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 02-093 Warsaw, Poland.
6
Institute of Bioinformatics, University of Georgia, Athens, Georgia 30602.
7
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602.
8
Department of Biology, University of Iowa, Iowa City, Iowa 52242.
9
Department of Cellular Biology, University of Georgia, Athens, Georgia 30602 jgaertig@uga.edu.

Abstract

The mechanisms that govern pattern formation within the cell are poorly understood. Ciliates carry on their surface an elaborate pattern of cortical organelles that are arranged along the anteroposterior and circumferential axes by largely unknown mechanisms. Ciliates divide by tandem duplication: the cortex of the predivision cell is remodeled into two similarly sized and complete daughters. In the conditional cdaI-1 mutant of Tetrahymena thermophila, the division plane migrates from its initially correct equatorial position toward the cell's anterior, resulting in unequal cell division, and defects in nuclear divisions and cytokinesis. We used comparative whole genome sequencing to identify the cause of cdaI-1 as a mutation in a Hippo/Mst kinase. CdaI is a cortical protein with a cell cycle-dependent, highly polarized localization. Early in cell division, CdaI marks the anterior half of the cell, and later concentrates at the posterior end of the emerging anterior daughter. Despite the strong association of CdaI with the new posterior cell end, the cdaI-1 mutation does not affect the patterning of the new posterior cortical organelles. We conclude that, in Tetrahymena, the Hippo pathway maintains an equatorial position of the fission zone, and, by this activity, specifies the relative dimensions of the anterior and posterior daughter cell.

KEYWORDS:

Hippo; Tetrahymena; ciliate; cytokinesis; polarity

PMID:
28413159
PMCID:
PMC5499192
DOI:
10.1534/genetics.117.200766
[Indexed for MEDLINE]
Free PMC Article

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