title: Recruitment Kinetics of Tropomyosin Tpm3.1 to Actin Filament Bundles in the Cytoskeleton Is Independent of Actin Filament Kinetics.
abstract: The actin cytoskeleton is a dynamic network of filaments that is involved in virtually every cellular process. Most actin filaments in metazoa exist as a co-polymer of actin and tropomyosin (Tpm) and the function of an actin filament is primarily defined by the specific Tpm isoform associated with it. However, there is little information on the interdependence of these co-polymers during filament assembly and disassembly. We addressed this by investigating the recovery kinetics of fluorescently tagged isoform Tpm3.1 into actin filament bundles using FRAP analysis in cell culture and in vivo in rats using intracellular intravital microscopy, in the presence or absence of the actin-targeting drug jasplakinolide. The mobile fraction of Tpm3.1 is between 50% and 70% depending on whether the tag is at the C- or N-terminus and whether the analysis is in vivo or in cultured cells. We find that the continuous dynamic exchange of Tpm3.1 is not significantly impacted by jasplakinolide, unlike tagged actin. We conclude that tagged Tpm3.1 may be able to undergo exchange in actin filament bundles largely independent of the assembly and turnover of actin.
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, New South Wales, Australia.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Appaduray
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, New South Wales, Australia.
authors.forename: Andrius
authors.initials: A
authors.lastname: Masedunskas
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, New South Wales, Australia.
authors.forename: Nicole S
authors.identifier: http://orcid.org/0000-0001-9799-7393
authors.initials: NS
authors.lastname: Bryce
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, New South Wales, Australia.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Lucas
authors.affiliation: The Kinghorn Cancer Center, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Warren
authors.affiliation: The Kinghorn Cancer Center, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Timpson
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, New South Wales, Australia.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Stear
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, New South Wales, Australia.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Gunning
authors.affiliation: Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, New South Wales, Australia.
authors.forename: Edna C
authors.initials: EC
authors.lastname: Hardeman
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D047630:Depsipeptides / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D014335:Tropomyosin / Q000378:metabolism*
chemical_list: D047630:Depsipeptides; D014335:Tropomyosin; C057531:jasplakinolide