Cell Polarity Regulates Biased Myosin Activity and Dynamics during Asymmetric Cell Division via Drosophila Rho Kinase and Protein Kinase N

Publication date: Available online 14 July 2017
Source:Developmental Cell
Author(s): Anna Tsankova, Tri Thanh Pham, David Salvador Garcia, Fabian Otte, Clemens Cabernard
Cell and tissue morphogenesis depends on the correct regulation of non-muscle Myosin II, but how this motor protein is spatiotemporally controlled is incompletely understood. Here, we show that in asymmetrically dividing Drosophila neural stem cells, cell intrinsic polarity cues provide spatial and temporal information to regulate biased Myosin activity. Using live cell imaging and a genetically encoded Myosin activity sensor, we found that Drosophila Rho kinase (Rok) enriches for activated Myosin on the neuroblast cortex prior to nuclear envelope breakdown (NEB). After NEB, the conserved polarity protein Partner of Inscuteable (Pins) sequentially enriches Rok and Protein Kinase N (Pkn) on the apical neuroblast cortex. Our data suggest that apical Rok first increases phospho-Myosin, followed by Pkn-mediated Myosin downregulation, possibly through Rok inhibition. We propose that polarity-induced spatiotemporal control of Rok and Pkn is important for unequal cortical expansion, ensuring correct cleavage furrow positioning and the establishment of physical asymmetry.

Graphical abstract

Teaser

Most cells divide symmetrically, but several cell types are known to generate unequal-sized siblings with different functions. Tsankova et al. report that the conserved polarity protein Pins controls the activity of the motor protein Myosin through two protein kinases, to ensure that Drosophila neural stem cells divide asymmetrically.


http://ift.tt/2v2jHvI