A novel small-molecule inhibitor reveals a possible role of kinesin-5 in anastral spindle-pole assembly.
The tetrameric plus-end-directed motor, kinesin-5, is essential for bipolar spindle assembly. Small-molecule inhibitors of kinesin-5 have been important tools for investigating its function, and some are currently under evaluation as anti-cancer drugs. Most inhibitors reported to date are ;non-competitive' and bind to a specific site on the motor head, trapping the motor in an ADP-bound state in which it has a weak but non-zero affinity for microtubules. Here, we used a novel ATP-competitive inhibitor, FCPT, developed at Merck (USA). We found that it induced tight binding of kinesin-5 onto microtubules in vitro. Using Xenopus egg-extract spindles, we found that FCPT not only blocked poleward microtubule sliding but also selectively induced loss of microtubules at the poles of bipolar spindles (and not asters or monoasters). We also found that the spindle-pole proteins TPX2 and gamma-tubulin became redistributed to the spindle equator, suggesting that proper kinesin-5 function is required for pole assembly.
Harvard Medical School, Department of Systems Biology, Boston, MA 02115, USA. aaron_groen@student.hms.harvard.edu
Aaron C
AC
Groen
Daniel
D
Needleman
Clifford
C
Brangwynne
Christain
C
Gradinaru
Brandon
B
Fowler
Ralph
R
Mazitschek
Timothy J
TJ
Mitchison
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects; D003521:Cyclopropanes / Q000737:chemistry / Q000494:pharmacology*; D016547:Kinesins / Q000037:antagonists & inhibitors*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology*; D054852:Small Molecule Libraries / Q000737:chemistry / Q000494:pharmacology*; D008941:Spindle Apparatus / Q000187:drug effects* / Q000378:metabolism*; D013844:Thiazoles / Q000737:chemistry / Q000494:pharmacology*; D014404:Tubulin / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism
C532016:2-(1-(4-fluorophenyl)cyclopropyl)-4-(pyridin-4-yl)thiazol; D018797:Cell Cycle Proteins; D003521:Cyclopropanes; C088335:KIF11 protein, Xenopus; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011725:Pyridines; D054852:Small Molecule Libraries; C486551:TPX2 protein, Xenopus; D013844:Thiazoles; D014404:Tubulin; D029867:Xenopus Proteins; D016547:Kinesins