title: Observing the growth of individual actin filaments in cell extracts by time-lapse atomic force microscopy.
abstract: High-resolution atomic force microscopy (AFM) was applied to directly observe the dynamic assembly of single actin filaments in HeLa cell extracts in vitro. The F-actin filaments established a dynamic network and formed different types of junctions and branches. The connections of this network were X-, Y- or T-shaped. It was found that the actin filaments were densely covered by endosomes and vesicles from the cell extract, which are thought to stabilize their structures. Using time-lapse AFM, the growth, shrinkage, branching and the interaction of actin filaments with endosomes could be characterized. Our results indicate that the majority of F-actin filaments are static in HeLa extract and that only a minor fraction of filaments undergo dynamic changes. Furthermore, the AFM imaging approach not only provides unique insights into the assembly and dynamics of actin networks; it also builds an avenue to study in vitro assays of complex biological systems.
authors.affiliation: BIOTEC, Technical University Dresden, 01609 Dresden, Germany.
authors.forename: Tiina
authors.initials: T
authors.lastname: Lehto
authors.forename: Marta
authors.initials: M
authors.lastname: Miaczynska
authors.forename: Marino
authors.initials: M
authors.lastname: Zerial
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Müller
authors.forename: Fedor
authors.initials: F
authors.lastname: Severin
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure*; D001704:Biopolymers / Q000096:biosynthesis; D002457:Cell Extracts / Q000737:chemistry; D011992:Endosomes / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D018625:Microscopy, Atomic Force
chemical_list: D001704:Biopolymers; D002457:Cell Extracts