title: Assembly of bipolar microtubule structures by passive cross-linkers and molecular motors.
abstract: During cell division, sister chromatids are segregated by the mitotic spindle, a bipolar assembly of interdigitating antiparallel polar filaments called microtubules. The spindle contains the midzone, a stable region of overlapping antiparallel microtubules, that is essential for maintaining bipolarity. Although a lot is known about the molecular players involved, the mechanism underlying midzone formation and maintenance is still poorly understood. We study the interaction of polar filaments that are cross-linked by molecular motors moving directionally and by passive cross-linkers diffusing along microtubules. Using a particle-based stochastic model, we find that the interplay of motors and passive cross-linkers can generate a stable finite overlap between a pair of antiparallel polar filaments. We develop a mean-field theory to study this mechanism in detail and investigate the influence of steric interactions between motors and passive cross-linkers on the overlap dynamics. In the presence of interspecies steric interactions, passive cross-linkers mimic the behavior of molecular motors and stable finite overlaps are generated even for non-cross-linking motors. Finally, we develop a mean-field theory for a bundle of aligned polar filaments and show that they can self-organize into a spindlelike pattern. Our work suggests possible ways as to how cells can generate spindle midzones and control their extensions.
authors.affiliation: Theoretische Physik, Universität des Saarlandes, Postfach 151150, 66041 Saarbrücken, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Johann
authors.affiliation: Theoretische Physik, Universität des Saarlandes, Postfach 151150, 66041 Saarbrücken, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Goswami
authors.affiliation: Theoretische Physik, Universität des Saarlandes, Postfach 151150, 66041 Saarbrücken, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Kruse
mesh_terms: D002455:Cell Division / Q000502:physiology; D008870:Microtubules / Q000378:metabolism*; D008941:Spindle Apparatus / Q000737:chemistry* / Q000378:metabolism*