title: Do nuclear envelope and intranuclear proteins reorganize during mitosis to form an elastic, hydrogel-like spindle matrix?
abstract: The idea of a spindle matrix has long been proposed in order to account for poorly understood features of mitosis. However, its molecular nature and structural composition have remained elusive. Here, we propose that the spindle matrix may be constituted by mainly nuclear-derived proteins that reorganize during the cell cycle to form an elastic gel-like matrix. We discuss this hypothesis in the context of recent observations from phylogenetically diverse organisms that nuclear envelope and intranuclear proteins form a highly dynamic and malleable structure that contributes to mitotic spindle function. We suggest that the viscoelastic properties of such a matrix may constrain spindle length while at the same time facilitating microtubule growth and dynamics as well as chromosome movement. A corollary to this hypothesis is that a key determinant of spindle size may be the amount of nuclear proteins available to form the spindle matrix. Such a matrix could also serve as a spatial regulator of spindle assembly checkpoint proteins during open and semi-open mitosis.
authors.affiliation: Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, 3156 Molecular Biology Building, Ames, IA 50011, USA.
authors.forename: Kristen M
authors.initials: KM
authors.lastname: Johansen
authors.forename: Arthur
authors.initials: A
authors.lastname: Forer
authors.forename: Changfu
authors.initials: C
authors.lastname: Yao
authors.forename: Jack
authors.initials: J
authors.lastname: Girton
authors.forename: Jørgen
authors.initials: J
authors.lastname: Johansen
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002467:Cell Nucleus / Q000378:metabolism*; D006801:Humans; D008938:Mitosis / Q000502:physiology*; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D008941:Spindle Apparatus / Q000737:chemistry / Q000378:metabolism*
chemical_list: D009687:Nuclear Proteins