Cdk11 is a RanGTP-dependent microtubule stabilization factor that regulates spindle assembly rate.
Production of Ran-guanosine triphosphate (GTP) around chromosomes induces local nucleation and plus end stabilization of microtubules (MTs). The nuclear protein TPX2 is required for RanGTP-dependent MT nucleation. To find the MT stabilizer, we affinity purify nuclear localization signal (NLS)-containing proteins from Xenopus laevis egg extracts. This NLS protein fraction contains the MT stabilization activity. After further purification, we used mass spectrometry to identify proteins in active fractions, including cyclin-dependent kinase 11 (Cdk11). Cdk11 localizes on spindle poles and MTs in Xenopus culture cells and egg extracts. Recombinant Cdk11 demonstrates RanGTP-dependent MT stabilization activity, whereas a kinase-dead mutant does not. Inactivation of Cdk11 in egg extracts blocks RanGTP-dependent MT stabilization and dramatically decreases the spindle assembly rate. Simultaneous depletion of TPX2 completely inhibits centrosome-dependent spindle assembly. Our results indicate that Cdk11 is responsible for RanGTP-dependent MT stabilization around chromosomes and that this local stabilization is essential for normal rates of spindle assembly and spindle function.
Yokoyama
Hideki
H
European Molecular Biology Laboratory, Heidelberg 69117, Germany. yokoyama@embl.de
Gruss
Oliver J
OJ
Rybina
Sofia
S
Caudron
Maïwen
M
Schelder
Malgorzata
M
Wilm
Matthias
M
Mattaj
Iain W
IW
Karsenti
Eric
E
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002457:Cell Extracts; D002460:Cell Line; D002875:Chromosomes / Q000235:genetics; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007313:Insecta; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D008938:Mitosis / Q000235:genetics*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D019913:Nuclear Localization Signals / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D009865:Oocytes; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029867:Xenopus Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014982:Xenopus laevis; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; D002457:Cell Extracts; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D010750:Phosphoproteins; C486551:TPX2 protein, Xenopus; D029867:Xenopus Proteins; C447612:CDK11a protein, human; D018844:Cyclin-Dependent Kinases; D020931:ran GTP-Binding Protein