Scythe: a novel reaper-binding apoptotic regulator

• Published in: The EMBO journal 1998-11, Vol.17 (21), p.6135-6143
• Main Authors: Thress, Kenneth, Henzel, William, Shillinglaw, Wendy, Kornbluth, Sally
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; apoptosis; Apoptosis - physiology; Carrier Proteins; Cell Extracts - chemistry; Cloning, Molecular; Cytochrome c Group - metabolism; Drosophila melanogaster - metabolism; Drosophila Proteins; Enzyme Activation - drug effects; Freshwater; Insect Proteins - chemistry; Mitochondria - metabolism; Molecular Sequence Data; Oocytes - metabolism; Peptide Fragments - pharmacology; Peptide Hydrolases - metabolism; Peptides - metabolism; Protein Binding - physiology; reaper; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Scythe; Sequence Analysis, DNA; Xenopus; Xenopus Proteins
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1093/emboj/17.21.6135

Reaper is a central regulator of apoptosis in Drosophila melanogaster . With no obvious catalytic activity or homology to other known apoptotic regulators, reaper's mechanism of action has been obscure. We recently reported that recombinant Drosophila reaper protein induced rapid mitochondrial cytochrome c release, caspase activation and apoptotic nuclear fragmentation in extracts of Xenopus eggs. We now report the purification of a 150 kDa reaper‐interacting protein from Xenopus egg extracts, which we have named Scythe. Scythe is highly conserved among vertebrates and contains a ubiquitin‐like domain near its N‐terminus. Immunodepletion of Scythe from extracts completely prevented reaper‐induced apoptosis without affecting apoptosis triggered by activated caspases. Moreover, a truncated variant of Scythe lacking the N‐terminal domain induced apoptosis even in the absence of reaper. These data suggest that Scythe is a novel apoptotic regulator that is an essential component in the pathway of reaper‐induced apoptosis.