title: Tum/RacGAP50C provides a critical link between anaphase microtubules and the assembly of the contractile ring in Drosophila melanogaster.
abstract: A central question in understanding cytokinesis is how the cleavage plane is positioned. Although the positioning signal is likely to be transmitted via the anaphase microtubule array to the cell cortex, exactly how the microtubule array determines the site of contractile ring formation remains unresolved. By analysing tum/RacGAP50C mutant Drosophila embryos we show that cells lacking Tum do not form furrows and fail to localise the key cytokinetic components Pebble (a RhoGEF), Aurora B kinase, Diaphanous, Pav-KLP and Anillin. The GAP activity of Tum is required for cytokinesis: in its absence cytokinesis fails early even though Tum is present on microtubules at the cell equator where the furrow should form. Disruption of the Pebble-interacting domain leaves Tum localised to the cell equator on cortically associated microtubules, again with no evidence of furrowing. These data support a model in which Tum/RacGAP, via its interaction with Pbl, provides a critical link between the anaphase microtubule spindle and cytokinetic furrow formation in Drosophila cells.
authors.affiliation: ARC Special Research Centre for the Molecular Genetics of Development and Molecular Genetics and Evolution Group, Research School of Biological Sciences, Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Zavortink
authors.forename: Nelida
authors.initials: N
authors.lastname: Contreras
authors.forename: Tracie
authors.initials: T
authors.lastname: Addy
authors.forename: Amy
authors.initials: A
authors.lastname: Bejsovec
authors.forename: Robert
authors.initials: R
authors.lastname: Saint
mesh_terms: D000705:Anaphase; D000818:Animals; D003285:Contractile Proteins / Q000172:deficiency / Q000378:metabolism*; D048749:Cytokinesis; D029721:Drosophila Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology / Q000378:metabolism*; D004475:Ectoderm / Q000378:metabolism; D047108:Embryonic Development; D004847:Epithelial Cells / Q000166:cytology; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000172:deficiency / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D013692:Telophase
chemical_list: D003285:Contractile Proteins; D029721:Drosophila Proteins; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D008869:Microtubule-Associated Proteins; C121865:Pbl protein, Drosophila; C490516:pav protein, Drosophila; C502951:tum protein, Drosophila