title: Acceleration of vacuolar regeneration and cell growth by overexpression of an aquaporin NtTIP1;1 in tobacco BY-2 cells.
abstract: Aquaporin is a water channel that increases water permeability through membranous structures. In plants, vacuoles are essential organelles that undergo dynamic volume changes during cell growth. To understand the contribution of aquaporins to plant cell growth, we developed a transgenic tobacco BY-2 cell line overexpressing the tonoplast intrinsic protein (TIP), gammaTIP. Vacuolar membranes of isolated vacuoles from gammaTIP-overexpressing cells showed higher water permeation activities than those from wild-type cells. We then examined the role of gammaTIP in vacuolar regeneration of evacuolated tobacco BY-2 protoplasts (miniprotoplasts). Vacuolar regeneration from thin to thick tube-network vacuoles and subsequent development of large vacuoles was accelerated in miniprotoplasts of this cell line. A parallel increase in the rate of cell expansion indicated a tight relationship between vacuolar development and cellular volume increases. Interestingly, overexpression of tobacco gammaTIP also enhanced cell division. Thus, increased vacuolar aquaporin activity may accelerate both cell expansion and cell division by increasing water permeability through the vacuolar membrane.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Okubo-Kurihara
authors.forename: Toshio
authors.initials: T
authors.lastname: Sano
authors.forename: Takumi
authors.initials: T
authors.lastname: Higaki
authors.forename: Natsumaro
authors.initials: N
authors.lastname: Kutsuna
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Hasezawa
mesh_terms: D000595:Amino Acid Sequence; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002463:Cell Membrane Permeability; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D011523:Protoplasts / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014026:Nicotiana / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C091845:gamma-TIP protein, plant