Cell polarity allows an enormous variety of specialised functions during development. Despite the range of contexts in which cell polarity is essential, the general steps of polarisation are the same: establishment, transduction, and segregation. We are investigating the molecular mechanisms of cell polarisation in one-cell C. elegans embryos.
C. elegans oocytes have no inherent polarity and fertilization itself does not polarize the embryo. About 30 minutes after fertilization, however, the symmetry of the one-cell embryo is broken when the anterior-posterior axis is established. This axis is defined by the segregation of PAR proteins into two distinct cortical domains, each domain occupying half the embryo. The anterior half (red) is defined by the widely conserved PAR-3–PAR-6–aPKC complex; the posterior half (green) is specified by the RING finger protein PAR-2 and the kinase PAR-1. The anterior-posterior polarity is reiterated through several cell divisions in the germ cell lineage of the embryo, similar to stem cell propagation.
