Spindle positioning during the asymmetric first cell division of Caenorhabditis elegans embryos

Novartis Found Symp. 2001;237:164-75; discussion 176-81. doi: 10.1002/0470846666.ch13.

Abstract

Cell division during development in many cases generates daughter cells that differ not only in fate, but also in size. We investigate the mechanisms that ensure proper spindle positioning during such asymmetric divisions using the one-cell stage Caenorhabditis elegans embryo as a model system. We utilized a UV laser microbeam as an in vivo microtubule-severing device to probe the forces driving spindle positioning. Our results indicate that extra-spindle pulling forces acting on the spindle poles dictate spindle position along the anterior-posterior embryonic axis. Importantly, forces acting on the posterior spindle pole appear more extensive than those acting on the anterior one, thus explaining the overall posterior spindle displacement that leads to the asymmetric division of the wild-type one-cell stage embryo. In separate work, we analysed a locus called zyg-8, which plays a key role in ensuring proper spindle positioning. Our data show that zyg-8 is required to promote microtubule growth and/or stability during anaphase. We identified the molecular nature of the zyg-8 locus in the course of a large-scale RNAi-based functional genomics screen. ZYG-8 harbours two notable protein domains: a Ca2+/calmodulin-dependent kinase domain, and a domain related to doublecortin, a human microtubule-associated protein involved in neuronal migration.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Caenorhabditis elegans / embryology*
  • Caenorhabditis elegans / physiology
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism
  • Cell Division / physiology*
  • Cell Polarity / physiology*
  • Embryo, Nonmammalian / cytology
  • Embryo, Nonmammalian / physiology*
  • Lasers
  • Microtubule-Associated Proteins*
  • Microtubules / metabolism
  • Neuropeptides / metabolism
  • Oocytes / physiology
  • Spindle Apparatus / metabolism*

Substances

  • Caenorhabditis elegans Proteins
  • Microtubule-Associated Proteins
  • Neuropeptides
  • doublecortin protein
  • zyg-8 protein, C elegans