CSPP and CSPP-L associate with centrosomes and microtubules and differently affect microtubule organization

J Cell Physiol. 2006 Oct;209(1):199-210. doi: 10.1002/jcp.20725.


We recently described the identification of a centrosome/spindle pole associated protein, CSPP, involved in cell cycle progression. Here we report a CSPP isoform denoted CSPP-L, with a 294 amino acids longer N-terminus and a 51 amino acids insertion located in the coiled-coil mid-domain. Expression analysis indicates an inverse cell cycle dependent regulation. CSPP mRNA expression is highest in G1 whereas CSPP-L expression is highest in G2/M. Ectopic expression of CSPP-L impairs cell cycle progression weaker in G1 than CSPP. Furthermore, normal mitotic phenotypes were observed in CSPP-L but not in CSPP transfectants. CSPP-L relocates from spindle microtubules and poles in metaphase to the mid-spindle in anaphase and concentrates at the mid-body in telophase/cytokinesis. CSPP-L high-expressing mitotic cells were predominantly characterized by lagging chromosomes or monopolar spindles, in contrast to the predominant multipolar spindles observed with CSPP expression. The different effects of CSPP and CSPP-L on microtubule organization in mitosis depend on the coiled-coil mid-domain insertion. The common C-terminal domain is required to repress that activity until mitosis. Notably, this C-terminal domain alone can associate with centrosomes in a microtubule independent manner. Taken together, CSPP and CSPP-L interact with centrosomes and microtubules and can differently affect microtubule organization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / genetics*
  • Cell Cycle Proteins / metabolism
  • Cell Cycle Proteins / physiology
  • Cell Cycle*
  • Cell Line
  • Centrosome / metabolism*
  • Humans
  • Microtubule-Associated Proteins / metabolism*
  • Microtubule-Associated Proteins / physiology
  • Microtubules / physiology*
  • Mitosis
  • Protein Structure, Tertiary
  • Spindle Apparatus
  • Transfection


  • CSPP1 protein, human
  • Cell Cycle Proteins
  • Microtubule-Associated Proteins