Ran-GTP coordinates regulation of microtubule nucleation and dynamics during mitotic-spindle assembly.
It was recently reported that GTP-bound Ran induces microtubule and pseudo-spindle assembly in mitotic egg extracts in the absence of chromosomes and centrosomes, and that chromosomes induce the assembly of spindle microtubules in these extracts through generation of Ran-GTP. Here we examine the effects of Ran-GTP on microtubule nucleation and dynamics and show that Ran-GTP has independent effects on both the nucleation activity of centrosomes and the stability of centrosomal microtubules. We also show that inhibition of Ran-GTP production, even in the presence of duplicated centrosomes and kinetochores, prevents assembly of a bipolar spindle in M-phase extracts.
European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany. carazosa@embl-heidelberg.de
R E
RE
Carazo-Salas
O J
OJ
Gruss
I W
IW
Mattaj
E
E
Karsenti
D000818:Animals; D018385:Centrosome / Q000378:metabolism; D002875:Chromosomes / Q000378:metabolism; D004261:DNA Replication; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D009865:Oocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D017231:Proto-Oncogene Proteins c-mos / Q000494:pharmacology; D013094:Spermatozoa / Q000737:chemistry / Q000166:cytology; D008941:Spindle Apparatus / Q000502:physiology*; D014982:Xenopus laevis; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D017231:Proto-Oncogene Proteins c-mos; D020931:ran GTP-Binding Protein