title: CDC-42 and RHO-1 coordinate acto-myosin contractility and PAR protein localization during polarity establishment in C. elegans embryos.
abstract: In C. elegans one-cell embryos, polarity is conventionally defined along the anteroposterior axis by the segregation of partitioning-defective (PAR) proteins into anterior (PAR-3, PAR-6) and posterior (PAR-1, PAR-2) cortical domains. The establishment of PAR asymmetry is coupled with acto-myosin cytoskeleton rearrangements. The small GTPases RHO-1 and CDC-42 are key players in cytoskeletal remodeling and cell polarity in a number of different systems. We investigated the roles of these two GTPases and the RhoGEF ECT-2 in polarity establishment in C. elegans embryos. We show that CDC-42 is required to remove PAR-2 from the cortex at the end of meiosis and to localize PAR-6 to the cortex. By contrast, RHO-1 activity is required to facilitate the segregation of CDC-42 and PAR-6 to the anterior. Loss of RHO-1 activity causes defects in the early organization of the myosin cytoskeleton but does not inhibit segregation of myosin to the anterior. We therefore propose that RHO-1 couples the polarization of the acto-myosin cytoskeleton with the proper segregation of CDC-42, which, in turn, localizes PAR-6 to the anterior cortex.
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany. schonegg@mpi-cbg.de
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schonegg
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Hyman
mesh_terms: D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000502:physiology*; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D016764:Cell Polarity / Q000502:physiology; D003285:Contractile Proteins / Q000235:genetics / Q000502:physiology; D003599:Cytoskeleton / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D015801:Helminth Proteins / Q000235:genetics / Q000502:physiology*; D007734:Kymography / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D034622:RNA Interference / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D003285:Contractile Proteins; D015801:Helminth Proteins; D011993:Recombinant Fusion Proteins; C081779:cdc-42 protein, C elegans; C087977:par-2 protein, C elegans; D000205:Actomyosin; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins