Inhibition of pp125FAK in cultured fibroblasts results in apoptosis.
The tyrosine kinase called pp125FAK is believed to play an important role in integrin-mediated signal transduction. pp125FAK is associated both functionally and spatially with integrins, which are the cell surface receptors for extracellular matrix components. Although the precise function of pp125FAK is not known, two possibilities have been proposed: pp125FAK may regulate the assembly of focal adhesions in spreading or migrating cells, or pp125FAK may participate in a signal transduction cascade to inform the nucleus that the cell is anchored. To test these models in living cells, a peptide representing the focal adhesion kinase (FAK)-binding site of the beta 1 tail was coupled to carrier protein and injected into cultured cells to competitively inhibit the binding of pp125FAK to endogenous integrin, thus inhibiting activation of pp125FAK on a cell-by-cell basis. In addition, an antibody directed against an epitope adjacent to the focal adhesion targeting sequence on pp125FAK was microinjected, as an alternative means of inhibiting pp125FAK activation. It was observed that when rounded cells were injected with either the integrin peptide or the anti-FAK antibody, the cells rapidly began to apoptose, within 4 h after injection. These results indicate that pp125FAK may play a critical role in suppressing apoptosis in fibroblasts.
Hungerford
J E
JE
Department of Cell Biology, School of Medicine, University of Virginia, Charlottesville 22908, USA.
Compton
M T
MT
Matter
M L
ML
Hoffstrom
B G
BG
Otey
C A
CA
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D001665:Binding Sites; D001667:Binding, Competitive; D015815:Cell Adhesion Molecules / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D002478:Cells, Cultured; D002642:Chick Embryo; D004789:Enzyme Activation; D005347:Fibroblasts; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019012:Integrin beta1 / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D015398:Signal Transduction
D015815:Cell Adhesion Molecules; D019012:Integrin beta1; D010455:Peptides; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases