Localization of active form of caspase-8 in mouse L929 cells induced by TNF treatment and polyglutamine aggregates

The relation between activation of caspase-8 and polyglutamine aggregates h as been focused. We prepared an antiserum (anti-m8D387) that recognizes the active form but not the preform of mouse caspase-8. We used immunostaining with anti-m8D387 antiserum to compare the localizations of activated mcasp ase-8 in L929 (clone 1422) cells induced by TNF and polyglutamine aggregate s. Anti-m8D387 was positive throughout cytoplasm of the TUNEL-positive cell s induced by TNF treatment, whereas the anti-m8D387 reactivity was not posi tive throughout cytoplasm of the cells expressing polyglutamine but was res tricted to polyglutamine aggregates. In contrast with TNF-treated cells, ce lls expressing anti-m8D387-positive cytoplasmic polyglutamine aggregates di d not undergo TUNEL-positive apoptosis. Thus activated caspase-8 associated with polyglutamine aggregates alone was not sufficient to induce TUNEL-pos itive apoptosis of L929 (clone 1422) cells. The distribution of activated c aspase-8 associated with polyglutamine aggregates may be essential for the polyglutamine-mediated cell death or downstream of caspase-8 may be differe nt in the TNF-treated cells and cells expressing polyglutamine. (C) 2000 Ac ademic Press.