Self-organizing actin waves as planar phagocytic cup structures.
Actin waves that travel on the planar membrane of a substrate-attached cell underscore the capability of the actin system to assemble into dynamic structures by the recruitment of proteins from the cytoplasm. The waves have no fixed shape, can reverse their direction of propagation and can fuse or divide. Actin waves separate two phases of the plasma membrane that are distinguished by their lipid composition. The area circumscribed by a wave resembles in its phosphoinositide content the interior of a phagocytic cup, leading us to explore the possibility that actin waves are in-plane phagocytic structures generated without the localized stimulus of an attached particle. Consistent with this view, wave-forming cells were found to exhibit a high propensity for taking up particles. Cells fed rod-shaped particles produced elongated phagocytic cups that displayed a zonal pattern that reflected in detail the actin and lipid pattern of free-running actin waves. Neutrophils and macrophages are known to spread on surfaces decorated with immune complexes, a process that has been interpreted as "frustrated" phagocytosis. We suggest that actin waves enable a phagocyte to scan a surface for particles that might be engulfed.
Max-Planck-Institut für Biochemie, Martinsried, Germany. gerisch@biochem.mpg.de
Günther
G
Gerisch
Mary
M
Ecke
Britta
B
Schroth-Diez
Silke
S
Gerwig
Ulrike
U
Engel
Lucinda
L
Maddera
Margaret
M
Clarke
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002448:Cell Adhesion / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D004023:Dictyostelium / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D008954:Models, Biological; D024462:Myosin Type II / Q000235:genetics; D010587:Phagocytosis / Q000502:physiology*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010873:Pinocytosis / Q000502:physiology; D012441:Saccharomyces cerevisiae; D053778:Thiazolidines / Q000494:pharmacology
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D018129:Phosphatidylinositol Phosphates; D053778:Thiazolidines; C060974:phosphatidylinositol 3,4,5-triphosphate; C060980:phosphatidylinositol 3,4-diphosphate; D024462:Myosin Type II; C037067:latrunculin A