Coordinated regulation of fibronectin fibril assembly and actin stress fiber formation.
Assembly of a fibronectin (FN) matrix is a multistep process which influences a number of cellular functions including intracellular cytoskeletal organization and signaling responses. We have previously reported on a recombinant FN (recFN), FN delta III1-7, which differs from native FN in its rate of fibril formation. To determine the intracellular consequences of a delay in assembly, we compared the distribution of cytoskeletal proteins during the formation of native and recFN matrices by immunofluorescence at various time points. CHO alpha 5 cell cytoskeleton was reorganized in response to both native and recFN matrix formation. Assembly of native FN induced a rapid reorganization of actin into stress fibers and colocalization of alpha 5 beta 1 integrin, focal adhesion kinase (FAK), vinculin, and paxillin to regions of cell-matrix contact. alpha 5 beta 1 integrins and FAK are also clustered upon binding of FN delta III1-7 to cells but actin reorganization and focal adhesion formation are delayed and appear to be dependent on the formation of FN delta III1-7 fibrils. These results suggest that the structural framework of the matrix plays an important role in the ability of FN to initiate intracellular responses.
Sechler
J L
JL
Department of Molecular Biology, Princeton University, NJ 08544-1014, USA.
Schwarzbauer
J E
JE
D000199:Actins / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D016466:CHO Cells; D015815:Cell Adhesion Molecules / Q000378:metabolism; D006224:Cricetinae; D003599:Cytoskeleton / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D017469:Receptors, Fibronectin / Q000235:genetics / Q000378:metabolism
D000199:Actins; D015815:Cell Adhesion Molecules; D005353:Fibronectins; D017469:Receptors, Fibronectin; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human