Src family kinases are required for integrin but not PDGFR signal transduction.
Src family kinases (SFKs) have been implicated as important regulators of ligand-induced cellular responses including proliferation, survival, adhesion and migration. Analysis of SFK function has been impeded by extensive redundancy between family members. We have generated mouse embryos harboring functional null mutations of the ubiquitously expressed SFKs Src, Yes and Fyn. This triple mutation leads to severe developmental defects and lethality by E9.5. To elucidate the molecular mechanisms underlying this phenotype, SYF cells (deficient for Src, Yes and Fyn) were derived and tested for their ability to respond to growth factors or plating on extracellular matrix. Our studies reveal that while Src, Yes and Fyn are largely dispensable for platelet-derived growth factor (PDGF)-induced signaling, they are absolutely required to mediate specific functions regulated by extracellular matrix proteins. Fibronectin-induced tyrosine phosphorylation of focal adhesion proteins, including the focal adhesion kinase FAK, was nearly eliminated in the absence of Src, Yes and Fyn. Furthermore, consistent with previous reports demonstrating the importance of FAK for cell migration, SYF cells displayed reduced motility in vitro. These results demonstrate that SFK activity is essential during embryogenesis and suggest that defects observed in SYF triple mutant embryos may be linked to deficiencies in signaling by extracellular matrix-coupled receptors.
Klinghoffer
R A
RA
Program in Developmental Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North-Mailstop C3-168, PO Box 19204, Seattle, WA 98109-1024, USA.
Sachsenmaier
C
C
Cooper
J A
JA
Soriano
P
P
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002465:Cell Movement; D004789:Enzyme Activation; D005353:Fibronectins / Q000494:pharmacology*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D005804:Genes, Lethal; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains / Q000196:embryology; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics; D051076:Proto-Oncogene Proteins c-fyn; D051575:Proto-Oncogene Proteins c-yes; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
D015815:Cell Adhesion Molecules; D005353:Fibronectins; D016023:Integrins; D010982:Platelet-Derived Growth Factor; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D051575:Proto-Oncogene Proteins c-yes; D016392:Proto-Oncogene Proteins pp60(c-src); C496051:Ptk2 protein, mouse; C496639:Yes1 protein, mouse; D019061:src-Family Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases