KL1 is a novel microtubule severing enzyme that regulates mitotic spindle architecture

Katanin is a microtubule severing enzyme with demonstrated roles in a variety of cellular activities including mitosis. Here we identify the closely related, but relatively uncharacterized human protein, Katanin-like 1 (KL1), as a novel mitotic regulator. Over expression of KL1 in tissue culture cells results in the complete disassembly of cellular microtubules strongly suggesting that it is an active microtubule severing protein. During mitosis, the localization of KL1 is restricted to spindle poles and is notably absent from centrosomes. This is in clear contrast to conventional Katanin whose localization extends from centrosomes onto poles. Consistent with its localization, siRNA depletion of KL1 from U2OS cells results in a specific and significant reduction in the density of microtubules at spindle poles and significantly increases spindle length. Depletion of KL1 also alters the distribution of gamma-tubulin at centrosomes/spindle poles. Despite its impact on spindle morphology, we could find no evidence that KL1 influences anaphase chromosome motility. Based on our findings, we propose that KL1-mediated microtubule severing is utilized to generate microtubule seeds within the poles and that loss of this activity alters the normal balance of motor-generated forces that determine spindle length.

[1]  F. McNally,et al.  Microtubule-severing enzymes. , 2010, Current opinion in cell biology.

[2]  P. Wadsworth,et al.  Imaging protein dynamics in live mitotic cells. , 2010, Methods.

[3]  A. Mogilner,et al.  Dynein Antagonizes Eg5 by Crosslinking and Sliding Antiparallel Microtubules , 2009, Current Biology.

[4]  Y. Jan,et al.  Drosophila IKK-related kinase Ik2 and Katanin p60-like 1 regulate dendrite pruning of sensory neuron during metamorphosis , 2009, Proceedings of the National Academy of Sciences.

[5]  Han Liu,et al.  Ab initio protein modelling reveals novel human MIT domains , 2009, FEBS letters.

[6]  G. Danuser,et al.  Regional variation of microtubule flux reveals microtubule organization in the metaphase meiotic spindle , 2008, The Journal of cell biology.

[7]  A. Munn,et al.  The Vps4 C‐terminal helix is a critical determinant for assembly and ATPase activity and has elements conserved in other members of the meiotic clade of AAA ATPases , 2008, The FEBS journal.

[8]  L. Qiang,et al.  The microtubule-severing proteins spastin and katanin participate differently in the formation of axonal branches. , 2008, Molecular biology of the cell.

[9]  Ronald D. Vale,et al.  Structural basis of microtubule severing by the hereditary spastic paraplegia protein spastin , 2008, Nature.

[10]  G. von Dassow,et al.  MCAK facilitates chromosome movement by promoting kinetochore microtubule turnover , 2007, The Journal of cell biology.

[11]  B. Lauring,et al.  AAA+ ATPases: Achieving Diversity of Function with Conserved Machinery , 2007, Traffic.

[12]  J. Conway,et al.  Arabidopsis katanin binds microtubules using a multimeric microtubule-binding domain. , 2007, Plant physiology and biochemistry : PPB.

[13]  J. Gaertig,et al.  Katanin regulates dynamics of microtubules and biogenesis of motile cilia , 2007, The Journal of cell biology.

[14]  H. Sudo,et al.  LAPSER1 is a putative cytokinetic tumor suppressor that shows the same centrosome and midbody subcellular localization pattern as p80 katanin , 2007, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[15]  G. C. Rogers,et al.  Three microtubule severing enzymes contribute to the “Pacman-flux” machinery that moves chromosomes , 2007, The Journal of cell biology.

[16]  J. Cole,et al.  Recognition of C-terminal amino acids in tubulin by pore loops in Spastin is important for microtubule severing , 2007, The Journal of cell biology.

[17]  A. Merdes,et al.  γ-tubulin complexes and microtubule organization , 2007 .

[18]  K. Oegema,et al.  Katanin controls mitotic and meiotic spindle length , 2006, The Journal of cell biology.

[19]  A. Hyman,et al.  Katanin Disrupts the Microtubule Lattice and Increases Polymer Number in C. elegans Meiosis , 2006, Current Biology.

[20]  L. Qiang,et al.  Tau Protects Microtubules in the Axon from Severing by Katanin , 2006, The Journal of Neuroscience.

[21]  D. Compton,et al.  Efficient Mitosis in Human Cells Lacking Poleward Microtubule Flux , 2005, Current Biology.

[22]  L. Qiang,et al.  Microtubules cut and run. , 2005, Trends in cell biology.

[23]  L. Qiang,et al.  Regulation of Microtubule Severing by Katanin Subunits during Neuronal Development , 2005, The Journal of Neuroscience.

[24]  G. C. Rogers,et al.  Spindle microtubules in flux , 2005, Journal of Cell Science.

[25]  J. Solowska,et al.  Axonal Growth Is Sensitive to the Levels of Katanin, a Protein That Severs Microtubules , 2004, The Journal of Neuroscience.

[26]  T. Mitchison,et al.  Microtubule plus-end dynamics in Xenopus egg extract spindles. , 2004, Molecular biology of the cell.

[27]  Sheila Christie,et al.  Yeast two-hybrid screens implicate DISC1 in brain development and function. , 2003, Biochemical and biophysical research communications.

[28]  F. McNally,et al.  Katanin-mediated microtubule severing can be regulated by multiple mechanisms. , 2002, Cell motility and the cytoskeleton.

[29]  F. McNally,et al.  Katanin inhibition prevents the redistribution of γ-tubulin at mitosis , 2002 .

[30]  E. Rugarli,et al.  Spastin, the protein mutated in autosomal dominant hereditary spastic paraplegia, is involved in microtubule dynamics. , 2002, Human molecular genetics.

[31]  G. C. Rogers,et al.  Microtubule motors in mitosis , 2000, Nature.

[32]  D. Agard,et al.  Structure of the γ-tubulin ring complex: a template for microtubule nucleation , 2000, Nature Cell Biology.

[33]  Yixian Zheng,et al.  A new function for the γ -tubulin ring complex as a microtubule minus-end cap , 2000, Nature Cell Biology.

[34]  F. McNally,et al.  Two domains of p80 katanin regulate microtubule severing and spindle pole targeting by p60 katanin. , 2000, Journal of cell science.

[35]  R. Vale,et al.  Microtubule disassembly by ATP-dependent oligomerization of the AAA enzyme katanin. , 1999, Science.

[36]  R. Vale,et al.  Katanin, a Microtubule-Severing Protein, Is a Novel AAA ATPase that Targets to the Centrosome Using a WD40-Containing Subunit , 1998, Cell.

[37]  C. Echeverri,et al.  Molecular characterization of the 50-kD subunit of dynactin reveals function for the complex in chromosome alignment and spindle organization during mitosis , 1996, The Journal of cell biology.

[38]  R. Vale,et al.  Identification of katanin, an ATPase that severs and disassembles stable microtubules , 1993, Cell.