title: Dynamic localization of G-actin during membrane protrusion in neuronal motility.
abstract: BACKGROUND
  Actin-based cell motility is fundamental for development, function, and malignant events in eukaryotic organisms. During neural development, axonal growth cones depend on rapid assembly and disassembly of actin filaments (F-actin) for their guided extension to specific targets for wiring. Monomeric globular actin (G-actin) is the building block for F-actin but is not considered to play a direct role in spatiotemporal control of actin dynamics in cell motility.
  
  
  RESULTS
  Here we report that a pool of G-actin dynamically localizes to the leading edge of growth cones and neuroblastoma cells to spatially elevate the G-/F-actin ratio that drives membrane protrusion and cell movement. Loss of G-actin localization leads to the cessation and retraction of membrane protrusions. Moreover, G-actin localization occurs asymmetrically in growth cones during attractive turning. Finally, we identify the actin monomer-binding proteins profilin and thymosin β4 as key molecules that localize actin monomers to the leading edge of lamellipodia for their motility.
  
  
  CONCLUSIONS
  Our results suggest that dynamic localization of G-actin provides a novel mechanism to regulate the spatiotemporal actin dynamics underlying membrane protrusion in cell locomotion and growth cone chemotaxis.
authors.affiliation: Department of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Chi Wai
authors.initials: CW
authors.lastname: Lee
authors.forename: Eric A
authors.initials: EA
authors.lastname: Vitriol
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Shim
authors.forename: Ariel L
authors.initials: AL
authors.lastname: Wise
authors.forename: Radhi P
authors.initials: RP
authors.lastname: Velayutham
authors.forename: James Q
authors.initials: JQ
authors.lastname: Zheng
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement; D002633:Chemotaxis; D020439:Growth Cones / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D051304:Profilins / Q000378:metabolism; D011554:Pseudopodia / Q000378:metabolism*; D013947:Thymosin / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis; D000099201:Thymosin beta(4)
chemical_list: D000199:Actins; D051304:Profilins; D013947:Thymosin; D000099201:Thymosin beta(4)