title: Synthetic activation of caspases: artificial death switches.
abstract: The development of safe vectors for gene therapy requires fail-safe mechanisms to terminate therapy or remove genetically altered cells. The ideal "suicide switch" would be nonimmunogenic and nontoxic when uninduced and able to trigger cell death independent of tissue type or cell cycle stage. By using chemically induced dimerization, we have developed powerful death switches based on the cysteine proteases, caspase-1 ICE (interleukin-1beta converting enzyme) and caspase-3 YAMA. In both cases, aggregation of the target protein is achieved by a nontoxic lipid-permeable dimeric FK506 analog that binds to the attached FK506-binding proteins, FKBPs. We find that intracellular cross-linking of caspase-1 or caspase-3 is sufficient to trigger rapid apoptosis in a Bcl-xL-independent manner, suggesting that these conditional proapoptotic molecules can bypass intracellular checkpoint genes, such as Bcl-xL, that limit apoptosis. Because these chimeric molecules are derived from autologous proteins, they should be nonimmunogenic and thus ideal for long-lived gene therapy vectors. These properties should also make chemically induced apoptosis useful for developmental studies, for treating hyperproliferative disorders, and for developing animal models to a wide variety of diseases.
authors.affiliation: Department of Microbiology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: MacCorkle
authors.forename: K W
authors.initials: KW
authors.lastname: Freeman
authors.forename: D M
authors.initials: DM
authors.lastname: Spencer
mesh_terms: D017209:Apoptosis; D002352:Carrier Proteins / Q000378:metabolism; D020170:Caspase 1; D053148:Caspase 3; D020169:Caspases; D003432:Cross-Linking Reagents; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016559:Tacrolimus / Q000378:metabolism / Q000494:pharmacology; D022021:Tacrolimus Binding Proteins; D051020:bcl-X Protein
chemical_list: C494811:BCL2L1 protein, human; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; D020170:Caspase 1; D022021:Tacrolimus Binding Proteins; D016559:Tacrolimus