title: Myosin-10 and actin filaments are essential for mitotic spindle function.
abstract: Mitotic spindles are microtubule-based structures responsible for chromosome partitioning during cell division. Although the roles of microtubules and microtubule-based motors in mitotic spindles are well established, whether or not actin filaments (F-actin) and F-actin-based motors (myosins) are required components of mitotic spindles has long been controversial. Based on the demonstration that myosin-10 (Myo10) is important for assembly of meiotic spindles, we assessed the role of this unconventional myosin, as well as F-actin, in mitotic spindles. We find that Myo10 localizes to mitotic spindle poles and is essential for proper spindle anchoring, normal spindle length, spindle pole integrity, and progression through metaphase. Furthermore, we show that F-actin localizes to mitotic spindles in dynamic cables that surround the spindle and extend between the spindle and the cortex. Remarkably, although proper anchoring depends on both F-actin and Myo10, the requirement for Myo10 in spindle pole integrity is F-actin independent, whereas F-actin and Myo10 actually play antagonistic roles in maintenance of spindle length.
authors.affiliation: Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA. sarah.woolner@manchester.ac.uk
authors.forename: Sarah
authors.initials: S
authors.lastname: Woolner
authors.forename: Lori L
authors.initials: LL
authors.lastname: O'Brien
authors.forename: Christiane
authors.initials: C
authors.lastname: Wiese
authors.forename: William M
authors.initials: WM
authors.lastname: Bement
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000818:Animals; D016764:Cell Polarity; D002470:Cell Survival; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D005260:Female; D006801:Humans; D008938:Mitosis; D008954:Models, Biological; D009218:Myosins / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D021381:Protein Transport; D008941:Spindle Apparatus / Q000378:metabolism*; D029867:Xenopus Proteins / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D000199:Actins; C492069:Myo10 protein, Xenopus; D029867:Xenopus Proteins; D009218:Myosins