Abstract
Necrotic and apoptotic changes have been rather conceptually defined, and have shown varying morphological and biochemical features depending on signaling pathways and cell lineages. In an attempt to investigate apoptotic and necrotic signals, we constructed a chimeric gene encoding an extracellular human Fas and intracytoplasmic human TNFR-1 (TNF receptor p55) and introduced it into murine NIH/3T3 cells for their heterotopic expression. Upon stimulation with an agonistic anti-human Fas monoclonal antibody those NIH/3T3 cell clones with the chimeric receptor showed cytopathic changes quite similar to those with the wild type Fas, although both receptors possess 'death' domains with different binding proteins. In this forced induction of death of the fibroblastic cells, we found thus that: 1) Fas signal induced complete cell death, 2) cytopathic changes in both NIH/3T3 derivatives were quite similar with irregular nuclear fragmentation and less distinct DNA fragmentation, and 3) intracytoplasmic domains were interchangeable between Fas and TNFR-1. This system may contribute to further analyses of the cell death mechanisms, including downstream Fas/TNFR-1 signaling.
