title: Katanin is responsible for the M-phase microtubule-severing activity in Xenopus eggs.
abstract: Microtubules are dynamic structures whose proper rearrangement during the cell cycle is essential for the positioning of membranes during interphase and for chromosome segregation during mitosis. The previous discovery of a cyclin B/cdc2-activated microtubule-severing activity in M-phase Xenopus egg extracts suggested that a microtubule-severing protein might play an important role in cell cycle-dependent changes in microtubule dynamics and organization. However, the isolation of three different microtubule-severing proteins, p56, EF1alpha, and katanin, has only confused the issue because none of these proteins is directly activated by cyclin B/cdc2. Here we use immunodepletion with antibodies specific for a vertebrate katanin homologue to demonstrate that katanin is responsible for the majority of M-phase severing activity in Xenopus eggs. This result suggests that katanin is responsible for changes in microtubules occurring at mitosis. Immunofluorescence analysis demonstrated that katanin is concentrated at a microtubule-dependent structure at mitotic spindle poles in Xenopus A6 cells and in human fibroblasts, suggesting a specific role in microtubule disassembly at spindle poles. Surprisingly, katanin was also found in adult mouse brain, indicating that katanin may have other functions distinct from its mitotic role.
authors.affiliation: Section of Molecular and Cellular Biology, University of California, Davis, Davis, California 95616, USA. fjmcnally@ucdavis.edu
authors.forename: F J
authors.initials: FJ
authors.lastname: McNally
authors.forename: S
authors.initials: S
authors.lastname: Thomas
mesh_terms: D000251:Adenosine Triphosphatases / Q000302:isolation & purification* / Q000378:metabolism / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D006801:Humans; D000074201:Katanin; D051379:Mice; D008870:Microtubules / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D008938:Mitosis / Q000187:drug effects*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010063:Ovum / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000201:enzymology / Q000502:physiology; D014981:Xenopus
chemical_list: D000251:Adenosine Triphosphatases; D000074201:Katanin