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

Groen AC, Cameron LA, Coughlin M, Miyamoto DT, Mitchison TJ, Ohi R
Curr Biol. 2004 14 (20): 1801-11

PMID: 15498487 · 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.

MeSH Terms (21)

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

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