Building the actin cytoskeleton: filopodia contribute to the construction of contractile bundles in the lamella.
Filopodia are rodlike extensions generally attributed with a guidance role in cell migration. We now show in fish fibroblasts that filopodia play a major role in generating contractile bundles in the lamella region behind the migrating front. Filopodia that developed adhesion to the substrate via paxillin containing focal complexes contributed their proximal part to stress fiber assembly, and filopodia that folded laterally contributed to the construction of contractile bundles parallel to the cell edge. Correlated light and electron microscopy of cells labeled for actin and fascin confirmed integration of filopodia bundles into the lamella network. Inhibition of myosin II did not subdue the waving and folding motions of filopodia or their entry into the lamella, but filopodia were not then integrated into contractile arrays. Comparable results were obtained with B16 melanoma cells. These and other findings support the idea that filaments generated in filopodia and lamellipodia for protrusion are recycled for seeding actomyosin arrays for use in retraction.
Nemethova
Maria
M
Institute of Molecular Biotechnology, Austrian Academy of Sciences, Vienna 1030, Austria.
Auinger
Sonja
S
Small
J Victor
JV
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D048430:Cell Shape / Q000502:physiology; D003595:Cytoplasmic Streaming / Q000502:physiology; D003599:Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure*; D022001:Focal Adhesions / Q000378:metabolism / Q000648:ultrastructure; D006054:Goldfish; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D024462:Myosin Type II / Q000378:metabolism; D051419:Paxillin / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D011554:Pseudopodia / Q000378:metabolism / Q000648:ultrastructure*; D013314:Stress, Mechanical
D000199:Actins; D002352:Carrier Proteins; D008840:Microfilament Proteins; D051419:Paxillin; C020324:fascin; D024462:Myosin Type II