Sizes of actin networks sharing a common environment are determined by the relative rates of assembly

• Published in: PLoS biology 2019-06, Vol.17 (6), p.e3000317-e3000317
• Main Authors: Antkowiak, Adrien, Guillotin, Audrey, Boiero Sanders, Micaela, Colombo, Jessica, Vincentelli, Renaud, Michelot, Alphée
• Format: Article
• Language: English
• Subjects: Actin; Actin Cytoskeleton - metabolism; Actin Depolymerizing Factors - metabolism; Actin-depolymerizing protein; Actin-related protein 2; Actin-Related Protein 2-3 Complex - metabolism; Actin-Related Protein 2-3 Complex - physiology; Actins - metabolism; Animals; Assembly; Biochemistry; Biochemistry, Molecular Biology; Biology and Life Sciences; Cell adhesion & migration; Cellular Biology; Cellular communication; Cofilin; Cytoplasm; Cytoskeleton; Depolymerization; Engineering and Technology; Filaments; Humans; Insects; Kinetics; Life Sciences; Microfilament Proteins - metabolism; Microfilament Proteins - physiology; Microspheres; Motility; Nanoparticles; Phenotypes; Physical Sciences; Physiological aspects; Polymerization; Polystyrene; Polystyrene resins; Profilin; Profilins - metabolism; Protein Interaction Maps - physiology; Proteins; Research and Analysis Methods; Subcellular Processes; Tropomyosin; Yeast
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.3000317

Within the cytoplasm of a single cell, several actin networks can coexist with distinct sizes, geometries, and protein compositions. These actin networks assemble in competition for a limited pool of proteins present in a common cellular environment. To predict how two distinct networks of actin filaments control this balance, the simultaneous assembly of actin-related protein 2/3 (Arp2/3)-branched networks and formin-linear networks of actin filaments around polystyrene microbeads was investigated with a range of actin accessory proteins (profilin, capping protein, actin-depolymerizing factor [ADF]/cofilin, and tropomyosin). Accessory proteins generally affected actin assembly rates for the distinct networks differently. These effects at the scale of individual actin networks were surprisingly not always correlated with corresponding loss-of-function phenotypes in cells. However, our observations agreed with a global interpretation, which compared relative actin assembly rates of individual actin networks. This work supports a general model in which the size of distinct actin networks is determined by their relative capacity to assemble in a common and competing environment.