title: Polarization of the C. elegans embryo by RhoGAP-mediated exclusion of PAR-6 from cell contacts.
abstract: Early embryos of some metazoans polarize radially to facilitate critical patterning events such as gastrulation and asymmetric cell division; however, little is known about how radial polarity is established. Early embryos of Caenorhabditis elegans polarize radially when cell contacts restrict the polarity protein PAR-6 to contact-free cell surfaces, where PAR-6 regulates gastrulation movements. We have identified a Rho guanosine triphosphatase activating protein (RhoGAP), PAC-1, which mediates C. elegans radial polarity and gastrulation by excluding PAR-6 from contacted cell surfaces. We show that PAC-1 is recruited to cell contacts, and we suggest that PAC-1 controls radial polarity by restricting active CDC-42 to contact-free surfaces, where CDC-42 binds and recruits PAR-6. Thus, PAC-1 provides a dynamic molecular link between cell contacts and PAR proteins that polarizes embryos radially.
authors.affiliation: Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA.
authors.forename: Dorian C
authors.initials: DC
authors.lastname: Anderson
authors.forename: Jason S
authors.initials: JS
authors.lastname: Gill
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Cinalli
authors.forename: Jeremy
authors.initials: J
authors.lastname: Nance
mesh_terms: D000818:Animals; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002450:Cell Communication; D002462:Cell Membrane / Q000378:metabolism*; D016764:Cell Polarity; D003593:Cytoplasm / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology* / Q000378:metabolism; D047108:Embryonic Development; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D054262:Gastrulation; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D020690:GTPase-Activating Proteins; C530006:PAC-1 protein, C elegans; D011993:Recombinant Fusion Proteins; C512642:par-6 protein, C elegans; C085379:rho GTPase-activating protein; C097238:PAR-3 protein, C elegans; D017346:Protein Serine-Threonine Kinases; D020764:cdc42 GTP-Binding Protein