Mammalian CLASPs are required for mitotic spindle organization and kinetochore alignment

Yuko Mimori-Kiyosue, Ilya Grigoriev, Hiroyuki Sasaki, Chiyuki Matsui, Anna Akhmanova, Shoichiro Tsukita, Ivan Vorobjev

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


CLASP1 and CLASP2 are homologous mammalian proteins, which associate with the ends of growing microtubules, as well as the cell cortex and the kinetochores of mitotic chromosomes. Previous studies have shown that in interphase cells CLASPs can attach microtubule plus ends to the cortex and stabilize them by repeatedly rescuing them from depolymerization. Here we show that CLASP1 and 2 play similar and redundant roles in organizing the mitotic apparatus in HeLa cells. Simultaneous depletion of both CLASPs causes mitotic spindle defects and a significant metaphase delay, which often results in abnormal exit from mitosis. Metaphase delay is associated with decreased kinetochore tension, increased kinetochore oscillations and more rapid microtubule growth. We show that the association of CLASP2 with the kinetochores relies on its C-terminal domain, but is independent of microtubules or association with CLIP-170. We propose that CLASPs exhibit at the kinetochores an activity similar to that at the cortex, providing apparent stabilization of microtubules by locally reducing the amplitude of growth/shortening episodes at the microtubule ends. This local stabilization of microtubules is essential for the formation of normal metaphase spindle, completion of anaphase and cytokinesis.

Original languageEnglish
Pages (from-to)845-857
Number of pages13
JournalGenes to Cells
Issue number8
Publication statusPublished - Aug 2006

ASJC Scopus subject areas

  • Genetics
  • Cell Biology

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