CDC-42 and RHO-1 coordinate acto-myosin contractility and PAR protein localization during polarity establishment in C. elegans embryos

Development. 2006 Sep;133(18):3507-16. doi: 10.1242/dev.02527. Epub 2006 Aug 9.

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.

MeSH terms

  • Actomyosin / metabolism*
  • Animals
  • Caenorhabditis elegans / genetics*
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / physiology*
  • Cell Cycle / genetics
  • Cell Cycle / physiology
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / physiology*
  • Cell Polarity / physiology
  • Contractile Proteins / genetics
  • Contractile Proteins / physiology
  • Cytoskeleton / metabolism
  • Embryo, Nonmammalian / cytology
  • Embryo, Nonmammalian / metabolism*
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / physiology*
  • Gene Expression Regulation, Developmental / genetics
  • Helminth Proteins / genetics
  • Helminth Proteins / physiology*
  • Kymography / methods
  • Microscopy, Fluorescence / methods
  • RNA Interference / physiology
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / physiology
  • rho GTP-Binding Proteins / genetics
  • rho GTP-Binding Proteins / physiology*

Substances

  • Caenorhabditis elegans Proteins
  • Cell Cycle Proteins
  • Contractile Proteins
  • Helminth Proteins
  • Recombinant Fusion Proteins
  • cdc-42 protein, C elegans
  • par-2 protein, C elegans
  • Actomyosin
  • GTP-Binding Proteins
  • rho GTP-Binding Proteins