Spatial mapping of integrin interactions and dynamics during cell migration by image correlation microscopy.
Image correlation microscopy methodology was extended and used to determine retrospectively the density, dynamics and interactions of alpha5-integrin in migrating cells. Alpha5-integrin is present in submicroscopic clusters containing 3-4 integrins before it is discernibly organized. The integrin in nascent adhesions, as identified by the presence of paxillin, is approximately 1.4 times more concentrated, approximately 4.5 times more clustered and much less mobile than in surrounding regions. Thus, while integrins are clustered throughout the cell, they differ in nascent adhesions and appear to initiate adhesion formation, despite their lack of visible organization. In more mature adhesions where the integrin is visibly organized there are approximately 900 integrins microm(-2) (about fivefold higher than surrounding regions). Interestingly, alpha5-integrin and alpha-actinin, but not paxillin, reside in a complex throughout the cell, where they diffuse and flow together, even in regions where they are not organized. During adhesion disassembly some integrins diffuse away slowly, alpha-actinin undergoes a directed movement at speeds similar to actin retrograde flow (0.29 microm min(-1)), while all of the paxillin diffuses away rapidly.
Department of Chemistry, McGill University, 801 Sherbrooke St. W. Montreal, Quebec H3A 2K6, Canada.
Paul W
PW
Wiseman
Claire M
CM
Brown
Donna J
DJ
Webb
Benedict
B
Hebert
Natalie L
NL
Johnson
Jeff A
JA
Squier
Mark H
MH
Ellisman
A F
AF
Horwitz
D000185:Actinin / Q000378:metabolism; D000465:Algorithms; D000818:Animals; D016466:CHO Cells; D002448:Cell Adhesion / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002465:Cell Movement / Q000502:physiology*; D006224:Cricetinae; D003595:Cytoplasmic Streaming / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D004058:Diffusion; D019044:Image Cytometry / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D039482:Integrin alpha5 / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal / Q000379:methods*; D008962:Models, Theoretical; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology
D003598:Cytoskeletal Proteins; D039482:Integrin alpha5; D016023:Integrins; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; D000185:Actinin