MOLECULAR-CLONING AND CHARACTERIZATION OF MOUSE CASPASE-8

Fas (APO-1/CD95) is a transmembrane receptor protein which induces apo ptosis upon activation. In apoptosis triggered by Fas, a subset of cys teine proteases designated caspases is activated, playing a central ro le as effector molecules. Among these caspases, human caspase-8 (FLICE /MACH/Mch5) has been isolated and shown to be indispensable for Fas-me diated apoptotic signaling. In this study, we isolated the mouse homol ogue to human caspase-8 from a BaF3 cell cDNA library. This molecule c onserved the death effector domain (DED) and protease domain as detect ed in human caspase-8, and was capable of inducing apoptosis in KB and Rat-1 cells when overexpressed. Expression of caspase-8 was detected in the various tissues of adult mouse and in embryos at 9.5 days and 1 7.5 days of development by Northern-blot analysis. Further, we isolate d a chromosomal gene for caspase-8 from a mouse genomic library and an alyzed the genomic structure of the isolated gene. This gene consisted of eight exons and seven introns spanning about 26 kb in the coding r egion.