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J Cell Biol. 2019 Dec 2;218(12):4195-4214. doi: 10.1083/jcb.201903152. Epub 2019 Oct 22.

Par-1 controls the composition and growth of cortical actin caps during Drosophila embryo cleavage.

Author information

1
Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.
2
Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada tony.harris@utoronto.ca.

Abstract

Cell structure depends on the cortex, a thin network of actin polymers and additional proteins underlying the plasma membrane. The cell polarity kinase Par-1 is required for cells to form following syncytial Drosophila embryo development. This requirement stems from Par-1 promoting cortical actin caps that grow into dome-like metaphase compartments for dividing syncytial nuclei. We find the actin caps to be a composite material of Diaphanous (Dia)-based actin bundles interspersed with independently formed, Arp2/3-based actin puncta. Par-1 and Dia colocalize along extended regions of the bundles, and both are required for the bundles and for each other's bundle-like localization, consistent with an actin-dependent self-reinforcement mechanism. Par-1 helps establish or maintain these bundles in a cortical domain with relatively low levels of the canonical formin activator Rho1-GTP. Arp2/3 is required for displacing the bundles away from each other and toward the cap circumference, suggesting interactions between these cytoskeletal components could contribute to the growth of the cap into a metaphase compartment.

PMID:
31641019
PMCID:
PMC6891076
[Available on 2020-06-02]
DOI:
10.1083/jcb.201903152

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