Cowan Group
Carrie Cowan (Group Leader)
Symmetry breaking during cell polarization
Cell polarity allows for spatial specialization within a cell, such as directed transport, migration, or growth. Cell polarity also controls asymmetric cell division, a dominant mechanism for dictating cell fate changes during development. The diverse roles of this fundamental organizational concept mean that understanding cell polarity is essential to understanding both normal development and diseases. We are investigating how cell polarity is established.
Movie: Polarity in 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.