title: Pushing forces drive the comet-like motility of microtubule arrays in Dictyostelium.
abstract: Overexpression of dynein fragments in Dictyostelium induces the movement of the entire interphase microtubule array. Centrosomes in these cells circulate through the cytoplasm at rates between 0.4 and 2.5 microm/s and are trailed by a comet-tail like arrangement of the microtubule array. Previous work suggested that these cells use a dynein-mediated pulling mechanism to generate this dramatic movement and that similar forces are at work to maintain the interphase MTOC position in wild-type cells. In the present study, we address the nature of the forces used to produce microtubule movement. We have used a laser microbeam to sever the connection between the motile centrosomes and trailing microtubules, demonstrating that the major force for such motility results from a pushing on the microtubules. We eliminate the possibility that microtubule assembly/disassembly reactions are significant contributors to this motility and suggest that the cell cortex figures prominently in locating force-producing molecules. Our findings indicate that interphase microtubules in Dictyostelium are subject to both dynein- and kinesin-like forces and that these act in concert to maintain centrosome position in the cell and to support the radial character of the microtubule network.
authors.affiliation: Division of Molecular Medicine, Wadsworth Center, Albany, NY 12201, USA.
authors.forename: Daniela A
authors.initials: DA
authors.lastname: Brito
authors.forename: Joshua
authors.initials: J
authors.lastname: Strauss
authors.forename: Valentin
authors.initials: V
authors.lastname: Magidson
authors.forename: Irina
authors.initials: I
authors.lastname: Tikhonenko
authors.forename: Alexey
authors.initials: A
authors.lastname: Khodjakov
authors.forename: Michael P
authors.initials: MP
authors.lastname: Koonce
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002465:Cell Movement; D048429:Cell Size; D018385:Centrosome / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004023:Dictyostelium; D004398:Dyneins / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D007399:Interphase; D007700:Kinetics; D007834:Lasers; D008869:Microtubule-Associated Proteins / Q000737:chemistry; D008870:Microtubules / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological
chemical_list: D000199:Actins; D008869:Microtubule-Associated Proteins; D049452:Green Fluorescent Proteins; D004398:Dyneins