title: Break of symmetry in regenerating tobacco protoplasts is independent of nuclear positioning.
abstract: Nuclear migration and positioning are crucial for the morphogenesis of plant cells. We addressed the potential role of nuclear positioning for polarity induction using an experimental system based on regenerating protoplasts, where the induction of a cell axis de novo can be followed by quantification of specific regeneration stages. Using overexpression of fluorescently tagged extranuclear (perinuclear actin basket, kinesins with a calponin homology domain (KCH)) as well as intranuclear (histone H2B) factors of nuclear positioning and time-lapse series of the early stages of regeneration, we found that nuclear position is no prerequisite for polarity formation. However, polarity formation and nuclear migration were both modulated in the transgenic lines, indicating that both phenomena depend on factors affecting cytoskeletal tensegrity and chromatin structure. We integrated these findings into a model where retrograde signals are required for polarity induction. These signals travel via the cytoskeleton from the nucleus toward targets at the plasma membrane.
authors.affiliation: Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Kaiserstr. 2, D-76133 Karlsruhe, Germany. Linda.Aimee@Brochhausen.com.
authors.forename: Linda
authors.initials: L
authors.lastname: Brochhausen
authors.affiliation: Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Kaiserstr. 2, D-76133 Karlsruhe, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Maisch
authors.affiliation: Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Kaiserstr. 2, D-76133 Karlsruhe, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Nick
mesh_terms: D000199:Actins / Q000378:metabolism; D019521:Body Patterning; D002467:Cell Nucleus / Q000378:metabolism*; D016764:Cell Polarity; D049109:Cell Proliferation; D002843:Chromatin / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism; D008954:Models, Biological; D010940:Plant Proteins / Q000378:metabolism; D011523:Protoplasts / Q000166:cytology* / Q000378:metabolism / Q000502:physiology*; D012038:Regeneration; D059008:Time-Lapse Imaging; D014026:Nicotiana / Q000502:physiology*
chemical_list: D000199:Actins; D002843:Chromatin; D006657:Histones; D010940:Plant Proteins; D049452:Green Fluorescent Proteins; D016547:Kinesins
keywords: Axis formation; cytoskeleton; nuclear migration; polarity induction; tobacco BY-2 protoplast