Spatial regulation of actin dynamics: A tropomyosinfree, actin-rich compartment of the leading edge

Vera M. Desmarais, Ilia Ichetovkin, John S. Condeelis, Sarah E. Hitchcock-DeGregori

Research output: Contribution to journalArticle

158 Citations (Scopus)

Abstract

Rapid polymerization of a network of short, branched actin filaments takes place at the leading edge of migrating cells, a compartment enriched in activators of actin polymerization such as the Arp2/3 complex and cofilin. Actin filaments elsewhere in the cell are long and unbranched. Results reported here show that the presence or absence of tropomyosin in these different actin-containing regions helps establish functionally distinct actin-containing compartments in the cell. Tropomyosin, an inhibitor of the Arp2/3 complex and cofilin function, was localized in relation to actin filaments, the Arp2/3 complex, and free barbed ends of actin filaments in MTLn3 cells, which rapidly extend flat lamellipodia following EGF stimulation. All tropomyosin isoforms examined using indirect immunofluorescence were relatively absent from the dynamic leading edge compartment, but did colocalize with actin structures deeper in the lamellipodium and in stress fibers. An in vitro light microscopy assay revealed that tropomyosin protects actin filaments from cofilin severing. The results suggest that tropomyosin-free actin filaments under the membrane can participate in rapid, dynamic processes that depend on interactions between the activities of the Arp2/3 complex and ADF/cofilin that tropomyosin inhibits elsewhere in the cell.

Original languageEnglish (US)
Pages (from-to)4649-4660
Number of pages12
JournalJournal of Cell Science
Volume115
Issue number23
DOIs
StatePublished - Dec 1 2002

Fingerprint

Tropomyosin
Actin Cytoskeleton
Actin-Related Protein 2-3 Complex
Actin Depolymerizing Factors
Actins
Pseudopodia
Polymerization
Stress Fibers
Indirect Fluorescent Antibody Technique
Epidermal Growth Factor
Microscopy
Protein Isoforms
Light
Membranes

Keywords

  • Actin
  • Arp2/3 complex
  • Cofilin
  • Cytoskeleton
  • Tropomyosin

ASJC Scopus subject areas

  • Cell Biology

Cite this

Spatial regulation of actin dynamics : A tropomyosinfree, actin-rich compartment of the leading edge. / Desmarais, Vera M.; Ichetovkin, Ilia; Condeelis, John S.; Hitchcock-DeGregori, Sarah E.

In: Journal of Cell Science, Vol. 115, No. 23, 01.12.2002, p. 4649-4660.

Research output: Contribution to journalArticle

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