title: XRHAMM functions in ran-dependent microtubule nucleation and pole formation during anastral spindle assembly.
abstract: 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.
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA. aaron_groen@students.hms.harvard.edu
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Groen
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Cameron
authors.forename: Margaret
authors.initials: M
authors.lastname: Coughlin
authors.forename: David T
authors.initials: DT
authors.lastname: Miyamoto
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mitchison
authors.forename: Ryoma
authors.initials: R
authors.lastname: Ohi
mesh_terms: D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000378:metabolism; D018385:Centrosome / Q000378:metabolism*; D002853:Chromatography, Liquid; D017931:DNA Primers; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D013058:Mass Spectrometry; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D017422:Sequence Analysis, DNA; D008941:Spindle Apparatus / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D017931:DNA Primers; C000623051:Hmmr protein, Xenopus; D008869:Microtubule-Associated Proteins; C489079:NUMA1 protein, Xenopus; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; C486551:TPX2 protein, Xenopus; D029867:Xenopus Proteins; D020931:ran GTP-Binding Protein