Kinesin-5 regulates the growth of the axon by acting as a brake on its microtubule array.
Kinesin-5 is a homotetrameric motor protein that interacts with adjacent microtubules in the mitotic spindle. Kinesin-5 is also highly expressed in developing postmitotic neurons. Axons of cultured neurons experimentally depleted of kinesin-5 grow up to five times longer than controls and display more branches. The faster growth rates are accompanied by a doubling of the frequency of transport of short microtubules, suggesting a major role for kinesin-5 in the balance of motor-driven forces on the axonal microtubule array. Live-cell imaging reveals that the effects on axonal length of kinesin-5 depletion are caused partly by a lower propensity of the axon and newly forming branches to undergo bouts of retraction. Overexpression of wild-type kinesin-5, but not a rigor mutant of kinesin-5, has the inverse effect on axonal length. These results indicate that kinesin-5 imposes restrictions on the growth of the axon and does so at least in part by generating forces on the axonal microtubule array.
Myers
Kenneth A
KA
Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19104, USA.
Baas
Peter W
PW
D000818:Animals; D001369:Axons / Q000502:physiology*; D002478:Cells, Cultured; D016547:Kinesins / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000502:physiology*; D051381:Rats
D008869:Microtubule-Associated Proteins; D016547:Kinesins