title: Interaction of PAR-6 with CDC-42 is required for maintenance but not establishment of PAR asymmetry in C. elegans.
abstract: Caenorhabditis elegans embryonic polarity requires the asymmetrically distributed proteins PAR-3, PAR-6 and PKC-3. The rho family GTPase CDC-42 regulates the activities of these proteins in mammals, flies and worms. To clarify its mode of action in C. elegans we disrupted the interaction between PAR-6 and CDC-42 in vivo, and also determined the distribution of GFP-tagged CDC-42 in the early embryo. Mutant PAR-6 proteins unable to interact with CDC-42 accumulated asymmetrically, at a reduced level, but this asymmetry was not maintained during the first division. We also determined that constitutively active GFP::CDC-42 becomes enriched in the anterior during the first cell cycle in a domain that overlaps with PAR-6. The asymmetry is dependent on PAR-2, PAR-5 and PAR-6. Furthermore, we found that overexpression of constitutively active GFP::CDC-42 increased the size of the anterior domain. We conclude that the CDC-42 interaction with PAR-6 is not required for the initial establishment of asymmetry but is required for maximal cortical accumulation of PAR-6 and to maintain its asymmetry.
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, 435 Biotechnology Building, Ithaca, NY 14853, USA.
authors.forename: Donato
authors.initials: D
authors.lastname: Aceto
authors.forename: Melissa
authors.initials: M
authors.lastname: Beers
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Kemphues
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D019521:Body Patterning; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D016764:Cell Polarity; D004625:Embryo, Nonmammalian / Q000378:metabolism / Q000502:physiology; D008969:Molecular Sequence Data; D011485:Protein Binding; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D029742:Caenorhabditis elegans Proteins; C087977:par-2 protein, C elegans; C106207:par-5 protein, C elegans; C512642:par-6 protein, C elegans; D020764:cdc42 GTP-Binding Protein