Polarization of PAR Proteins by Advective Triggering of a Pattern-Forming System

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Science  20 Oct 2011:
DOI: 10.1126/science.1208619


In the Caenorhabditis elegans zygote, a conserved network of partitioning defective 4 (PAR) polarity proteins segregate into an anterior and a posterior domain, facilitated by flows of the cortical actomyosin meshwork. The physical mechanisms by which stable asymmetric PAR distributions arise from transient cortical flows remain unclear. We present evidence that PAR polarity arises from coupling of advective transport by the flowing cell cortex to a multistable PAR reaction-diffusion system. By inducing transient PAR segregation, advection serves as a mechanical trigger for the formation of a PAR pattern within an otherwise stably unpolarized system. We suggest that passive advective transport in an active and flowing material may be a general mechanism for mechanochemical pattern formation in developmental systems.

  • Present Address: Department of Physics, and Department of Applied Mathematics and Theoretical Physics, University of Cambridge, UK.

  • Present Address: Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.

  • Present Address: Department of Physics, Harvard University, Cambridge, MA 02138, USA.

  • § Present Address: IFISC (CSIC-UIB), UIB Campus, E-07122 Palma de Mallorca, Spain.