Tracking retrograde flow in keratocytes: News from the front

Pascal Vallotton, Gaudenz Danuser, Sophie Bohnet, Jean Jacques Meister, Alexander B. Verkhovsky

Research output: Contribution to journalArticlepeer-review

117 Scopus citations


Actin assembly at the leading edge of the cell is believed to drive protrusion, whereas membrane resistance and contractile forces result in retrograde flow of the assembled actin network away from the edge. Thus, cell motion and shape changes are expected to depend on the balance of actin assembly and retrograde flow. This idea, however, has been undermined by the reported absence of flow in one of the most spectacular models of cell locomotion, fish epidermal keratocytes. Here, we use enhanced phase contrast and fluorescent speckle microscopy and particle tracking to analyze the motion of the actin network in keratocyte lamellipodia. We have detected retrograde flow throughout the lamellipodium at velocities of 1-3 μm/min and analyzed its organization and relation to the cell motion during both unobstructed, persistent migration and events of cell collision. Freely moving cells exhibited a graded flow velocity increasing toward the sides of the lamellipodium. In colliding cells, the velocity decreased markedly at the site of collision, with striking alteration of flow in other lamellipodium regions. Our findings support the universality of the flow phenomenon and indicate that the maintenance of keratocyte shape during locomotion depends on the regulation of both retrograde flow and actin polymerization.

Original languageEnglish (US)
Pages (from-to)1223-1231
Number of pages9
JournalMolecular biology of the cell
Issue number3
StatePublished - Mar 2005

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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