title: A Cholesterol-Dependent Endocytic Mechanism Generates Midbody Tubules During Cytokinesis.
abstract: Cytokinesis is the final stage of cell division and produces two independent daughter cells. Vesicles derived from internal membrane stores, such as the Golgi, lysosomes, and early and recycling endosomes accumulate at the intracellular bridge (ICB) during cytokinesis. Here, we use electron tomography to show that many ICB vesicles are not independent but connected, forming a newly described ICB vesicular structure - narrow tubules that are often branched. These 'midbody tubules' labelled with horseradish peroxidase (HRP) within 10 min after addition to the surrounding medium demonstrating that they are derived from endocytosis. HRP-labelled vesicles and tubules were observed at the rim of the ICB after only 1 min, suggesting that midbody tubules are likely to be generated by local endocytosis occurring at the ICB rim. Indeed, at least one tubule was open to the extracellular space, indicative of a local origin within the ICB. Inhibition of cholesterol-dependent endocytosis by exposure to methyl-β-cyclodextrin and filipin reduced formation of HRP-labelled midbody tubules, and induced multinucleation following ICB formation. In contrast, dynamin inhibitors, which block clathrin-mediated endocytosis, induced multinucleation but had no effect on the formation of HRP-labelled midbody tubules. Therefore, our data reveal the existence of a cholesterol-dependent endocytic pathway occurring locally at the ICB, which contributes to the accumulation of vesicles and tubules that contribute to the completion of cytokinesis.
authors.affiliation: Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia.
authors.forename: Emma
authors.initials: E
authors.lastname: Kettle
authors.affiliation: Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Page
authors.affiliation: Institute for Molecular Biosciences, Queensland Bioscience Precinct, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors.forename: Garry P
authors.initials: GP
authors.lastname: Morgan
authors.affiliation: Department of Molecular Physiology, School of Medicine, University of Western Sydney, Penrith, NSW, 2751, Australia.
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Malladi
authors.affiliation: Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia.
authors.forename: Chin L
authors.initials: CL
authors.lastname: Wong
authors.affiliation: Westmead Millennium Institute for Medical Research, 176 Hawkesbury Road, Westmead, NSW, 2145, Australia.
authors.forename: Ross A
authors.initials: RA
authors.lastname: Boadle
authors.affiliation: Institute for Molecular Biosciences, Queensland Bioscience Precinct, The University of Queensland, Brisbane, Queensland, 4072, Australia.
authors.forename: Brad J
authors.initials: BJ
authors.lastname: Marsh
authors.affiliation: Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Robinson
authors.affiliation: Children's Medical Research Institute, The University of Sydney, 214 Hawkesbury Road, Westmead, NSW, 2145, Australia.
authors.forename: Megan
authors.initials: M
authors.lastname: Chircop
mesh_terms: D002784:Cholesterol / Q000378:metabolism*; D048749:Cytokinesis / Q000502:physiology*; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D008854:Microscopy, Electron / Q000379:methods; D047392:beta-Cyclodextrins / Q000378:metabolism
chemical_list: D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol; D006735:Horseradish Peroxidase
keywords: abscission; cytokinesis; endocytosis; midbody tubules; vesicles