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A Rae1-containing ribonucleoprotein complex is required for mitotic spindle assembly

Michael D Blower1, Maxence Nachury, Rebecca Heald

  • 1Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA.

Cell
|April 27, 2005
PubMed

Insights

Researchers discovered Rae1 (an mRNA export protein) is crucial for building mitotic spindles, independent of cell division centers. RNA is essential for this process, playing a direct role in spindle assembly and morphogenesis.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Centrosome-independent microtubule polymerization requires a RanGTP gradient.
  • RanGTP regulates mitotic cargoes via importin beta.

Purpose of the Study:

  • To identify spindle assembly factors regulated by the RanGTP/importin beta pathway.
  • To investigate the role of Rae1 in mitotic spindle assembly.

Main Methods:

  • Activity-based assay in Xenopus egg extracts.
  • Purification and characterization of Rae1.
  • Depletion experiments in extracts and cells.
  • In vitro microtubule stabilization assays.

Main Results:

  • Rae1 was purified as a spindle assembly factor regulated by RanGTP/importin beta.
  • Rae1 is a microtubule-associated protein that binds importin beta.
  • Rae1 depletion inhibits mitotic spindle assembly.
  • Rae1 functions within a ribonucleoprotein complex requiring RNA.
  • RNA associates with the mitotic spindle and is essential for its assembly.

Conclusions:

  • Rae1 is a novel spindle assembly factor regulated by the RanGTP pathway.
  • RNA plays a direct, translation-independent role in spindle assembly and morphogenesis.

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