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PMID: 20418872 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

Electron tomography reveals unbranched networks of actin filaments in lamellipodia.

Nature cell biology ·Vol. 12 ·No. 5 ·2010-05-00 ·Pages 429-35

Urban E, Jacob S, Nemethova M, Resch GP, Small JV

Abstract

Eukaryotic cells can initiate movement using the forces exerted by polymerizing actin filaments to extend lamellipodial and filopodial protrusions. In the current model, actin filaments in lamellipodia are organized in a branched, dendritic network. We applied electron tomography to vitreously frozen 'live' cells, fixed cells and cytoskeletons, embedded in vitreous ice or in deep-negative stain. In lamellipodia from four cell types, including rapidly migrating fish keratocytes, we found that actin filaments are almost exclusively unbranched. The vast majority of apparent filament junctions proved to be overlapping filaments, rather than branched end-to-side junctions. Analysis of the tomograms revealed that actin filaments terminate at the membrane interface within a zone several hundred nanometres wide at the lamellipodium front, and yielded the first direct measurements of filament densities. Actin filament pairs were also identified as lamellipodium components and bundle precursors. These data provide a new structural basis for understanding actin-driven protrusion during cell migration.

MeSH Terms
Actin Cytoskeleton/ultrastructure Actins/physiology Animals Cell Movement Cells, Cultured Cryoelectron Microscopy Cytoskeleton Electron Microscope Tomography/methods Fishes Humans Keratinocytes/cytology Pseudopodia/ultrastructure
Chemicals
Actins
Authors & Affiliations
5 authors, click to expand affiliations / ORCID
Urban Edit
Institute of Molecular Biotechnology, Vienna 1030, Austria.
Jacob Sonja
Nemethova Maria
Resch Guenter P
Small J Victor
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Article Info
Journal
Nature cell biology
Abbr.
Nat Cell Biol
ISSN
1476-4679
DOI
10.1038/ncb2044
Published
2010-05-00
Epub
2010-00-25
Pages
429-35
Language
English
Region
England
NLM ID
100890575
Subset
IM
Grants
Austrian Science Fund FWF · P 21292 · Austria
Corrections
CommentIn
PMID: 21892140
External Links
PubMed source DOI: 10.1038/ncb2044 View journal details
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