Recombinant apoptin multimers kill tumor cells but are nontoxic and epitope-shielded in a normal-cell-specific fashion

摘要: Apoptin, a protein derived from chicken anemia virus, induces apoptosis in human transformed or tumor cells but not normal cells. When produced bacteria as recombinant fusion with maltose-binding (MBP-Apoptin), Apoptin forms distinct, stable multimeric complex that is remarkably homogeneous and uniform. Here, using cytoplasmic microinjection, we showed MBP-Apoptin multimers retained the characteristics of ectopically expressed wild-type Apoptin; namely, complexes translocated to nucleus induced apoptosis, whereas they remained cytoplasm normal, primary exerted no apparent toxic effect. In cells, formed increasingly large, organelle-sized globular bodies time postinjection eventually lost ability be detected by immunofluorescence analysis. Costaining an acidotrophic marker indicated these structures did correspond lysosomes. Immunoprecipitation studies fully antibody-accessible regardless buffer stringency when microinjected into contrast, was only recoverable under stringent lysis conditions, milder conditions became shielded on two epitopes spanning entire protein. Further biochemical analysis long-term fate aggregates their eventual elimination. Our results provide first example tumor-specific apoptosis-inducing aggregate essentially sequestered factors present healthy, nontransformed This characteristic should reveal more about cellular interactions this viral well further enhance its safety potential therapeutic agent.