Control of Cell Polarity and Asymmetric Division in C. elegans - Current Topics in Developmental Biology - page 71

Van Gogh and Prickle so that b -catenin mainly regulates transcription in nu-
clei in the canonical Wnt signaling. (Note that the Wnt/ b -catenin asymme-
try pathway controls both cell polarity and transcription.) The acquisition of
the asymmetric localization of Van Gogh and Prickle might enable cells to
communicate with their neighbor to coordinate their polarity, while, at least
in C. elegans seam cells, polarity of individual cells is independently
controlled by Wnts. Such functions of Wnt might be still retained in other
organisms to coordinate cell polarity regulated by the PCP pathway.
Although functions of Wnt in the PCP regulation are often considered as
permissive signals, it was recently suggested that Wnt functions as global
cue of cell polarity in chicken limb bud ( Gao et al., 2011 ). In Drosophila wing
in which polarity is synchronized primarily by cooperation between the
FAT-Dachsous system and the PCP signaling, the presence of additional
extracellular signals that regulate polarity orientation has been predicted
( Strutt, 2008; Wu & Mlodzik, 2009 ). Although the PCP regulation in
Drosophila is thought to be Wnt independent, based on the lack of the
PCP phenotype in wingless mutants, it may be possible that multiple Wnts
redundantly control polarity as is the case in C. elegans seam cells. Even in
C. elegans , it is not yet clear whether Wnts function as global cues for
orientating polarity. Therefore, it will be important to clarify roles of
Wnts in the control of polarity orientation in C. elegans .
ACKNOWLEDGMENTS
I would like to thank Ralf Schnabel and members of Sawa lab. for comments on the chapter.
This work was supported by Grants-in-Aid for Scientific Research from the Ministry of
Education, Culture, Sports, Science, and Technology of Japan.
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