Drosophila Anterior-Posterior Polarity Requires Actin-Dependent PAR-1 Recruitment to the Oocyte Posterior

Curr Biol. 2006 Jun 6;16(11):1090-5. doi: 10.1016/j.cub.2006.04.001.

Abstract

The Drosophila anterior-posterior axis is established at stage 7 of oogenesis when the posterior follicle cells signal to polarize the oocyte microtubule cytoskeleton. This requires the conserved PAR-1 kinase, which can be detected at the posterior of the oocyte in immunostainings from stage 9. However, this localization depends on Oskar localization, which requires the earlier PAR-1-dependent microtubule reorganization, indicating that Oskar-associated PAR-1 cannot establish oocyte polarity. Here we analyze the function of the different PAR-1 isoforms and find that only PAR-1 N1 isoforms can completely rescue the oocyte polarity phenotype. Furthermore, PAR-1 N1 is recruited to the posterior cortex of the oocyte at stage 7 in response to the polarizing follicle cell signal, and this requires actin, but not microtubules. This suggests that posterior PAR-1 N1 polarizes the microtubule cytoskeleton. PAR-1 N1 localization is mediated by a cortical targeting domain and a conserved anterior-lateral exclusion signal in its C-terminal linker domain. PAR-1 is also required for the polarization of the C. elegans zygote and is recruited to the posterior cortex in an actin-dependent manner. Our results therefore identify a molecular parallel between axis formation in Drosophila and C. elegans and make Drosophila PAR-1 N1 the earliest known marker for the polarization of the oocyte.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Actins / physiology*
  • Amino Acid Sequence
  • Animals
  • Body Patterning / physiology*
  • Caenorhabditis elegans / growth & development
  • Caenorhabditis elegans / metabolism
  • Conserved Sequence
  • Drosophila / enzymology*
  • Drosophila / genetics
  • Drosophila / growth & development*
  • Drosophila Proteins / analysis
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / physiology*
  • Glycogen Synthase Kinase 3
  • Microtubules / metabolism
  • Molecular Sequence Data
  • Oocytes / cytology
  • Oocytes / enzymology*
  • Oocytes / growth & development
  • Protein Isoforms / analysis
  • Protein Isoforms / chemistry
  • Protein Isoforms / metabolism
  • Protein Kinases / analysis
  • Protein Kinases / chemistry
  • Protein Kinases / physiology*
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases
  • Recombinant Fusion Proteins / analysis

Substances

  • Actins
  • Drosophila Proteins
  • Protein Isoforms
  • Recombinant Fusion Proteins
  • Protein Kinases
  • Protein-Serine-Threonine Kinases
  • Glycogen Synthase Kinase 3
  • Par-1 protein, Drosophila