Mobile actin clusters and traveling waves in cells recovering from actin depolymerization.
At the leading edge of a motile cell, actin polymerizes in close apposition to the plasma membrane. Here we ask how the machinery for force generation at a leading edge is established de novo after the global depolymerization of actin. The depolymerization is accomplished by latrunculin A, and the reorganization of actin upon removal of the drug is visualized in Dictyostelium cells by total internal reflection fluorescence microscopy. The actin filament system is reorganized in three steps. First, F-actin assembles into globular complexes that move along the bottom surface of the cells at velocities up to 10 microm/min. These clusters are transient structures that eventually disassemble, fuse, or divide. In a second step, clusters merge into a contiguous zone at the cell border that spreads and gives rise to actin waves traveling on a planar membrane. Finally, normal cell shape and motility are resumed. These data show that the initiation of actin polymerization is separated in Dictyostelium from front protrusion, and that the coupling of polymerization to protrusion is a later step in the reconstitution of a leading edge.
Gerisch
Günther
G
Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany. gerisch@biochem.mpg.de
Bretschneider
Till
T
Müller-Taubenberger
Annette
A
Simmeth
Evelyn
E
Ecke
Mary
M
Diez
Stefan
S
Anderson
Kurt
K
D000199:Actins / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure*; D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004023:Dictyostelium / Q000737:chemistry / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D011726:Pyridinium Compounds / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; C092350:FM 4-64; D020409:Molecular Motor Proteins; D046912:Multiprotein Complexes; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D013844:Thiazoles; D053778:Thiazolidines; C037067:latrunculin A