Centrosome fragments and microtubules are transported asymmetrically away from division plane in anaphase.
Spinning disc confocal microscopy of LLCPK1 cells expressing GFP-tubulin was used to demonstrate that microtubules (MTs) rapidly elongate to the cell cortex after anaphase onset. Concurrently, individual MTs are released from the centrosome and the centrosome fragments into clusters of MTs. Using cells expressing photoactivatable GFP-tubulin to mark centrosomal MT minus ends, a sevenfold increase in MT release in anaphase is documented as compared with metaphase. Transport of both individually released MTs and clusters of MTs is directionally biased: motion is directed away from the equatorial region. Clusters of MTs retain centrosomal components at their focus and the capacity to nucleate MTs. Injection of mRNA encoding nondegradable cyclin B blocked centrosome fragmentation and the stimulation of MT release in anaphase despite allowing anaphase-like chromosome segregation. Biased MT release may provide a mechanism for MT-dependent positioning of components necessary for specifying the site of contractile ring formation.
Rusan
Nasser M
NM
Department of Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, USA.
Wadsworth
Patricia
P
D000705:Anaphase / Q000502:physiology*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D016203:CDC2 Protein Kinase / Q000378:metabolism; D018385:Centrosome / Q000378:metabolism*; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D018374:LLC-PK1 Cells; D008870:Microtubules / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism; D013552:Swine; D014404:Tubulin / Q000235:genetics / Q000378:metabolism
D019926:Cyclin B; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014404:Tubulin; D016203:CDC2 Protein Kinase