XRHAMM functions in ran-dependent microtubule nucleation and pole formation during anastral spindle assembly

Curr Biol. 2004 Oct 26;14(20):1801-11. doi: 10.1016/j.cub.2004.10.002.


Background: The regulated assembly of microtubules is essential for bipolar spindle formation. Depending on cell type, microtubules nucleate through two different pathways: centrosome-driven or chromatin-driven. The chromatin-driven pathway dominates in cells lacking centrosomes.

Results: Human RHAMM (receptor for hyaluronic-acid-mediated motility) was originally implicated in hyaluronic-acid-induced motility but has since been shown to associate with centrosomes and play a role in astral spindle pole integrity in mitotic systems. We have identified the Xenopus ortholog of human RHAMM as a microtubule-associated protein that plays a role in focusing spindle poles and is essential for efficient microtubule nucleation during spindle assembly without centrosomes. XRHAMM associates both with gamma-TuRC, a complex required for microtubule nucleation and with TPX2, a protein required for microtubule nucleation and spindle pole organization.

Conclusions: XRHAMM facilitates Ran-dependent, chromatin-driven nucleation in a process that may require coordinate activation of TPX2 and gamma-TuRC.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Cell Cycle Proteins / metabolism
  • Centrosome / metabolism*
  • Chromatography, Liquid
  • DNA Primers
  • Fluorescent Antibody Technique
  • Immunoblotting
  • Mass Spectrometry
  • Microtubule-Associated Proteins / genetics*
  • Microtubule-Associated Proteins / metabolism*
  • Microtubules / metabolism*
  • Molecular Sequence Data
  • Neoplasm Proteins / metabolism
  • Nuclear Proteins / metabolism
  • Phosphoproteins / metabolism
  • Plasmids / genetics
  • Sequence Analysis, DNA
  • Spindle Apparatus / metabolism*
  • Xenopus
  • Xenopus Proteins / metabolism
  • ran GTP-Binding Protein / metabolism


  • Cell Cycle Proteins
  • DNA Primers
  • Hmmr protein, Xenopus
  • Microtubule-Associated Proteins
  • NUMA1 protein, Xenopus
  • Neoplasm Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • TPX2 protein, Xenopus
  • Xenopus Proteins
  • ran GTP-Binding Protein

Associated data

  • GENBANK/AY729653