Polarization of the C. elegans zygote proceeds via distinct establishment and maintenance phases

Adrian A. Cuenca, Aaron Schetter, Donato Aceto, Kenneth Kemphues, Geraldine Seydoux

Research output: Contribution to journalReview article

Abstract

Polarization of the C elegans zygote along the anterior-posterior axis depends on cortically enriched (PAR) and cytoplasmic (MEX-5/6) proteins, which function together to localize determinants (e.g. PIE-1) in response to a polarizing cue associated with the sperm asters. Using time-lapse microscopy and GFP fusions, we have analyzed the localization dynamics of PAR-2, PAR-6, MEX-5, MEX-6 and PIE-1 in wild-type and mutant embryos. These studies reveal that polarization involves two genetically and temporally distinct phases. During the first phase (establishment), the sperm asters at one end of the embryo exclude the PAR-3/PAR-6/PKC3 complex from the nearby cortex, allowing the ring finger protein PAR-2 to accumulate in an expanding 'posterior' domain. Onset of the establishment phase involves the non-muscle myosin NMY-2 and the 14-3-3 protein PAR-5. The kinase PAR-1 and the CCCH finger proteins MEX-5 and MEX-6 also function during the establishment phase in a feedback loop to regulate growth of the posterior domain. The second phase begins after pronuclear meeting, when the sperm asters begin to invade the anterior. During this phase (maintenance), PAR-2 maintains anterior-posterior polarity by excluding the PAR-3/PAR-6/PKC3 complex from the posterior. These findings provide a model for how PAR and MEX proteins convert a transient asymmetry into a stably polarized axis.

Original languageEnglish (US)
Pages (from-to)1255-1265
Number of pages11
JournalDevelopment
Volume130
Issue number7
DOIs
StatePublished - Apr 1 2003

Keywords

  • C. elegans
  • Embryo
  • Par genes
  • Polarity

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology

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