title: Gelsolin mediates calcium-dependent disassembly of Listeria actin tails.
abstract: The role of intracellular Ca2+ in the regulation of actin filament assembly and disassembly has not been clearly defined. We show that reduction of intracellular free Ca2+ concentration ([Ca2+]i) to <40 nM in Listeria monocytogenes-infected, EGFP-actin-transfected Madin-Darby canine kidney cells results in a 3-fold lengthening of actin filament tails. This increase in tail length is the consequence of marked slowing of the actin filament disassembly rate, without a significant change in assembly rate. The Ca2+-sensitive actin-severing protein gelsolin concentrates in the Listeria rocket tails at normal resting [Ca2+]i and disassociates from the tails when [Ca2+]i is lowered. Reduction in [Ca2+]i also blocks the severing activity of gelsolin, but not actin-depolymerizing factor (ADF)/cofilin microinjected into Listeria-infected cells. In Xenopus extracts, Listeria tail lengths are also calcium-sensitive, markedly shortening on addition of calcium. Immunodepletion of gelsolin, but not Xenopus ADF/cofilin, eliminates calcium-sensitive actin-filament shortening. Listeria tail length is also calcium-insensitive in gelsolin-null mouse embryo fibroblasts. We conclude that gelsolin is the primary Ca2+-sensitive actin filament recycling protein in the cell and is capable of enhancing Listeria actin tail disassembly at normal resting [Ca2+]i (145 nM). These experiments illustrate the unique and complementary functions of gelsolin and ADF/cofilin in the recycling of actin filaments.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of Florida College of Medicine, Gainesville, FL 32610, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Larson
authors.forename: Serge
authors.initials: S
authors.lastname: Arnaudeau
authors.forename: Bruce
authors.initials: B
authors.lastname: Gibson
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Ryoko
authors.initials: R
authors.lastname: Krause
authors.forename: Binghua
authors.initials: B
authors.lastname: Hao
authors.forename: James R
authors.initials: JR
authors.lastname: Bamburg
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Lew
authors.forename: Nicolas
authors.initials: N
authors.lastname: Demaurex
authors.forename: Frederick
authors.initials: F
authors.lastname: Southwick
mesh_terms: D051339:Actin Depolymerizing Factors; D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D018260:Gelsolin / Q000378:metabolism*; D008089:Listeria monocytogenes / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins; D002614:Chelating Agents; D018260:Gelsolin; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse; D002118:Calcium