CLASPs function redundantly to regulate astral microtubules in the C. elegans embryo

Dev Biol. 2012 Aug 15;368(2):242-54. doi: 10.1016/j.ydbio.2012.05.016. Epub 2012 May 19.


Microtubule dynamics are thought to play an important role in regulating microtubule interactions with cortical force generating motor proteins that position the spindle during asymmetric cell division. CLASPs are microtubule-associated proteins that have a conserved role in regulating microtubule dynamics in diverse cell types. Caenorhabditis elegans has three CLASP homologs in its genome. CLS-2 is known to localize to kinetochores and is needed for chromosome segregation at meiosis and mitosis; however CLS-1 and CLS-3 have not been reported to have any role in embryonic development. Here, we show that depletion of CLS-2 in combination with either CLS-1 or CLS-3 results in defects in nuclear rotation, maintenance of spindle length, and spindle displacement in the one-cell embryo. Polarity is normal in these embryos, but reduced numbers of astral microtubules reach all regions of the cortex at the time of spindle positioning. Analysis of the microtubule plus-end tracker EB1 also revealed a reduced number of growing microtubules reaching the cortex in CLASP depleted embryos, but the polymerization rate of astral microtubules was not slower than in wild type. These results indicate that C. elegans CLASPs act partially redundantly to regulate astral microtubules and position the spindle during asymmetric cell division. Further, we show that these spindle pole-positioning roles are independent of the CLS-2 binding proteins HCP-1 and HCP-2.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Blotting, Western
  • Caenorhabditis elegans / embryology
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism
  • Caenorhabditis elegans Proteins / physiology*
  • Cytoplasm / metabolism
  • Embryo, Nonmammalian / cytology
  • Embryo, Nonmammalian / embryology
  • Embryo, Nonmammalian / metabolism*
  • Immunohistochemistry
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism*
  • Microscopy, Confocal
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Microtubule-Associated Proteins / physiology*
  • Microtubules / metabolism*
  • Mitosis
  • RNA Interference
  • Spindle Apparatus / metabolism*
  • Time Factors


  • CLS-1 protein, C elegans
  • CLS-2 protein, C elegans
  • CLS-3 protein, C elegans
  • Caenorhabditis elegans Proteins
  • Luminescent Proteins
  • Microtubule-Associated Proteins