title: Preprophase band formation and cortical division zone establishment: RanGAP behaves differently from microtubules during their band formation.
abstract: Correct positioning of the division plane is a prerequisite for plant morphogenesis. The preprophase band (PPB) is a key intracellular structure of division site determination. PPB forms in G2 phase as a broad band of microtubules (MTs) that narrows in prophase and specializes few-micrometer-wide cortical belt region, named the cortical division zone (CDZ), in late prophase. The PPB comprises several molecules, some of which act as MT band organization and others remain in the CDZ marking the correct insertion of the cell plate in telophase. Ran GTPase-activating protein (RanGAP) is accumulated in the CDZ and forms a RanGAP band in prophase. However, little is known about when and how RanGAPs gather in the CDZ, and especially with regard to their relationships to MT band formation. Here, we examined the spatial and temporal distribution of RanGAPs and MTs in the preprophase of onion root tip cells using confocal laser scanning microscopy and showed that the RanGAP band appeared in mid-prophase as the width of MT band was reduced to nearly 7 µm. Treatments with cytoskeletal inhibitors for 15 min caused thinning or broadening of the MT band but had little effects on RanGAP band in mid-prophase and most of late prophase cells. Detailed image analyses of the spatial distribution of RanGAP band and MT band showed that the RanGAP band positioned slightly beneath the MT band in mid-prophase. These results raise a possibility that RanGAP behaves differently from MTs during their band formation.
authors.affiliation: a Graduate School of Life Science; University of Hyogo ; Himeji , Hyogo , Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Yabuuchi
authors.affiliation: a Graduate School of Life Science; University of Hyogo ; Himeji , Hyogo , Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Nakai
authors.affiliation: b Graduate School of Life Science; University of Hyogo ; Akou , Hyogo , Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Sonobe
authors.affiliation: a Graduate School of Life Science; University of Hyogo ; Himeji , Hyogo , Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamauchi
authors.affiliation: a Graduate School of Life Science; University of Hyogo ; Himeji , Hyogo , Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Mineyuki
mesh_terms: D000906:Antibodies / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D004136:Dinitrobenzenes / Q000494:pharmacology; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D018519:Meristem / Q000166:cytology; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D019697:Onions / Q000166:cytology; D010940:Plant Proteins / Q000378:metabolism*; D011418:Prophase / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D062211:Spatio-Temporal Analysis; D013424:Sulfanilamides / Q000494:pharmacology; D053778:Thiazolidines / Q000494:pharmacology; D014404:Tubulin / Q000378:metabolism
chemical_list: D000906:Antibodies; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004136:Dinitrobenzenes; D020690:GTPase-Activating Proteins; D010940:Plant Proteins; D013424:Sulfanilamides; D053778:Thiazolidines; D014404:Tubulin; C012465:oryzalin; C037068:latrunculin B
keywords: RanGAP; confocal laser scanning microscope; cortical division zone; microtubule; onion root meristems; preprophase band