title: The availability of filament ends modulates actin stochastic dynamics in live plant cells.
abstract: A network of individual filaments that undergoes incessant remodeling through a process known as stochastic dynamics comprises the cortical actin cytoskeleton in plant epidermal cells. From images at high spatial and temporal resolution, it has been inferred that the regulation of filament barbed ends plays a central role in choreographing actin organization and turnover. How this occurs at a molecular level, whether different populations of ends exist in the array, and how individual filament behavior correlates with the overall architecture of the array are unknown. Here we develop an experimental system to modulate the levels of heterodimeric capping protein (CP) and examine the consequences for actin dynamics, architecture, and cell expansion. Significantly, we find that all phenotypes are the opposite for CP-overexpression (OX) cells compared with a previously characterized cp-knockdown line. Specifically, CP OX lines have fewer filament-filament annealing events, as well as reduced filament lengths and lifetimes. Further, cp-knockdown and OX lines demonstrate the existence of a subpopulation of filament ends sensitive to CP concentration. Finally, CP levels correlate with the biological process of axial cell expansion; for example, epidermal cells from hypocotyls with reduced CP are longer than wild-type cells, whereas CP OX lines have shorter cells. On the basis of these and other genetic studies in this model system, we hypothesize that filament length and lifetime positively correlate with the extent of axial cell expansion in dark-grown hypocotyls.
authors: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-2064 Institute of Plant Sciences, Volcani Center, Bet-Dagan 50250, Israel Institut de Recherches en Technologie et Sciences pour le Vivant, Laboratoire de Physiologie Cellulaire et Végétale, Comissariat a l'Energie Atomique/Centre National de la Recherche Scientifique/Institute de la Recherche Agronomique/Université Joseph Fourier, F38054 Grenoble, France Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907.
authors: Jiejie
authors: J
authors: Li
authors: Benjamin H
authors: BH
authors: Staiger
authors: Jessica L
authors: JL
authors: Henty-Ridilla
authors: Mohamad
authors: M
authors: Abu-Abied
authors: Einat
authors: E
authors: Sadot
authors: Laurent
authors: L
authors: Blanchoin
authors: Christopher J
authors: CJ
authors: Staiger
mesh_terms: D051344:Actin Capping Proteins / Q000096:biosynthesis* / Q000235:genetics; D008841:Actin Cytoskeleton / Q000378:metabolism*; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D018546:Hypocotyl / Q000166:cytology; D007091:Image Processing, Computer-Assisted; D008840:Microfilament Proteins / Q000378:metabolism; D059828:Plant Cells; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism*; D013269:Stochastic Processes
chemical_list: D051344:Actin Capping Proteins; D008840:Microfilament Proteins