Suppression of chemically induced apoptosis but not necrosis of renal proximal tubular epithelial (LLC-PK1) cells by focal adhesion kinase (FAK). Role of FAK in maintaining focal adhesion organization after acute renal cell injury.
Decreased phosphorylation of focal adhesion kinase (FAK) is associated with loss of focal adhesions and actin stress fibers and precedes the onset of apoptosis in renal epithelial cells caused by nephrotoxicants (Van de Water, B., Nagelkerke, J. F., and Stevens, J. L. (1999) J. Biol. Chem. 274, 13328-13337). The role of FAK in the control of apoptosis caused by nephrotoxicants was further investigated in LLC-PK1 cells that were stably transfected with either green fluorescent protein (GFP)-FAK or dominant negative acting deletion mutants of FAK, GFP-FAT, and GFP-FRNK. GFP-FAT and GFP-FRNK delayed the formation of focal adhesions and prevented the localization of endogenous (phosphorylated) FAK at these sites. GFP-FAT and GFP-FRNK overexpression potentiated the onset of apoptosis caused by the nephrotoxicant dichlorovinyl-cysteine. This was associated with an increased activation of caspase-3. GFP-FAT also potentiated apoptosis caused by doxorubicin but not cisplatin. The potentiation of apoptosis by GFP-FAT was related to an almost complete dephosphorylation of FAK; this did not occur in cells overexpressing only GFP. This dephosphorylation was associated with a pronounced loss of focal adhesion organization in GFP-FAT cells, in association with loss of tyrosine phosphorylation of paxillin. In conclusion, the data indicate an important role of cell-matrix signaling in the control of chemically induced apoptosis; loss of FAK activity caused by toxic chemicals results in perturbations of focal adhesion organization with a subsequent inactivation of associated (signaling) molecules and loss of survival signaling.
van de Water
B
B
Division of Toxicology, Leiden Amsterdam Center for Drug Research, Leiden University, 2300 RA Leiden, The Netherlands. b.water@LACDR.LeidenUniv.nl
Houtepen
F
F
Huigsloot
M
M
Tijdens
I B
IB
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle; D002455:Cell Division; D002470:Cell Survival; D002945:Cisplatin / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000201:enzymology*; D051416:Focal Adhesion Protein-Tyrosine Kinases; D017353:Gene Deletion; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins; D018374:LLC-PK1 Cells; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009336:Necrosis; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D013997:Time Factors; D014162:Transfection
D000970:Antineoplastic Agents; D003432:Cross-Linking Reagents; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D008164:Luminescent Proteins; D051419:Paxillin; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D004317:Doxorubicin; D011505:Protein-Tyrosine Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin