Organization of Actin Networks in Intact Filopodia

Ohad Medalia, Martin Beck, Mary Ecke, Igor Weber, Ralph Neujahr, Wolfgang Baumeister, Günther Gerisch

Research output: Contribution to journalArticlepeer-review

118 Scopus citations

Abstract

Filopodia are finger-like extensions of the cell surface that are involved in sensing the environment [1], in attachment of particles for phagocytosis [2], in anchorage of cells on a substratum [3], and in the response to chemoattractants or other guidance cues [4-6]. Filopodia present an excellent model for actin-driven membrane protrusion. They grow at their tips by the assembly of actin and are stabilized along their length by a core of bundled actin filaments. To visualize actin networks in their native membrane-anchored state, filopodia of Dictyostelium cells were subjected to cryo-electron tomography. At the site of actin polymerization, a peculiar structure, the "terminal cone," is built of short filaments fixed with their distal end to the filopod's tip and with their proximal end to the flank of the filopod. The backbone of the filopodia consists of actin filaments that are shorter than the entire filopod and aligned in parallel or obliquely to the filopod's axis. We hypothesize that growth of the highly dynamic filopodia of Dictyostelium is accompanied by repetitive nucleation of actin polymerization at the filopod tip, followed by the rearrangement of filaments within the shaft.

Original languageEnglish
Pages (from-to)79-84
Number of pages6
JournalCurrent Biology
Volume17
Issue number1
DOIs
StatePublished - 9 Jan 2007

Keywords

  • CELLBIO

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