title: Subcellular localization and role of Ran1 in Tetrahymena thermophila amitotic macronucleus.
abstract: Amitosis, a direct method of cell division is common in ciliated protozoan, fungi and some animal and plant cells. During amitosis, intranuclear microtubules are reorganized into specified arrays which assist in separation of nucleus, despite lack of a bipolar spindle. However, the regulation of amitosis is not understood. Here, we focused on the localization and role of mitotic spindle assembly regulator: Ran GTPase (Ran1) in macronuclear amitosis in binucleated protozoan Tetrahymena thermophila. HA-tagged Ran1 was localized in the macronucleus throughout the cell cycle of Tetrahymena during vegetative growth, and the accessory factor binding domains of Ran1 contributed to its macronuclear localization. Incomplete somatic knockout of RAN1 resulted in aberrant intramacronuclear microtubule array formation, missegregation of macronuclear chromosomes and ultimately blocked macronuclei proliferation. When the Ran1 cycle was perturbed by overexpression of Ran1T25N (GDP-bound Ran1-mimetic) or Ran1Q70L (GTP-bound Ran1-mimetic), intramacronuclear microtubule assembly was inhibited or multi-micronucleate cells formed. These results suggest that Ran GTPase pathway is involved in assembly of a specialized intramacronuclear microtubule network and coordinates amitotic progression in Tetrahymena.
authors.affiliation: Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, China.
authors.forename: Haixia
authors.initials: H
authors.lastname: Liang
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Huaru
authors.initials: H
authors.lastname: Tian
authors.forename: Xuxia
authors.initials: X
authors.lastname: Yang
authors.forename: Aihua
authors.initials: A
authors.lastname: Liang
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002455:Cell Division / Q000235:genetics; D003593:Cytoplasm / Q000378:metabolism; D055786:Gene Knockout Techniques; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D048648:Macronucleus / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008938:Mitosis / Q000235:genetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D016808:Tetrahymena thermophila / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D015800:Protozoan Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020931:ran GTP-Binding Protein