Stabilization of Cell Polarity by the C. Elegans RING Protein PAR-2

Dev Cell. 2006 Feb;10(2):199-208. doi: 10.1016/j.devcel.2005.12.015.

Abstract

Asymmetric localization of PAR proteins is a hallmark of polarized cells, but the mechanisms that create PAR asymmetry are not well understood. In the C. elegans zygote, PAR asymmetry is initiated by a transient actomyosin contraction, which sweeps the PAR-3/PAR-6/PKC-3 complex toward the anterior pole of the egg. The RING finger protein PAR-2 accumulates in a complementary pattern in the posterior cortex. Here we present evidence that PAR-2 participates in a feedback loop to stabilize polarity. PAR-2 is a target of the PKC-3 kinase and is excluded from the anterior cortex by PKC-3-dependent phosphorylation. The RING domain of PAR-2 is required to overcome inhibition by PKC-3 and stabilize PAR-2 on the posterior cortex. Cortical PAR-2 in turn prevents PAR-3/PAR-6/PKC-3 from returning to the posterior, in a PAR-1- and PAR-5-dependent manner. Our findings suggest that reciprocal inhibitory interactions among PAR proteins stabilize polarity by reinforcing an initial asymmetry in PKC-3.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Caenorhabditis elegans / cytology*
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / chemistry
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Polarity / physiology*
  • Down-Regulation
  • Feedback
  • Female
  • Genes, Helminth
  • Male
  • Molecular Sequence Data
  • Phosphorylation
  • Protein Kinase C / metabolism
  • Protein Structure, Tertiary
  • Sequence Homology, Amino Acid
  • Zygote / cytology
  • Zygote / metabolism

Substances

  • Caenorhabditis elegans Proteins
  • par-2 protein, C elegans
  • PKC-3 protein
  • Protein Kinase C