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Caspase‐mediated cleavage of APC results in an amino‐terminal fragment with an intact armadillo repeat domain
Author(s) -
WEBB STEPHANIE JOHNSON,
NICHOLSON DONALD,
BUBB VIVIEN J.,
WYLLIE ANDREW H.
Publication year - 1999
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.13.2.339
Subject(s) - cleavage (geology) , cleavage factor , microbiology and biotechnology , cleavage stimulation factor , caspase , biology , xenopus , nlrp1 , schneider 2 cells , caspase 3 , apoptosis , chemistry , biochemistry , programmed cell death , messenger rna , gene , paleontology , fracture (geology) , rna , rna interference
ABSTRACT During the effector phase of apoptosis, caspase activation appears to be responsible for the distinctive structural changes of apoptosis and perhaps for some of the changes in function of the doomed cells. There is therefore interest in identifying caspase substrates and the details of the cleavage events. Here we define precisely the event responsible for generation of a stable 90 kDa fragment from the oncosuppressor protein adenomatous polyposis coli (APC). Using synthetic radiolabeled APC peptides as substrate, we demonstrate cleavage by cytosolic extracts from preapoptotic cells. This cleavage was reproduced by recombinant caspase‐3 and blocked by a tetrapeptide inhibitor Ac‐DEVD‐CHO, which is specific for caspase‐3 family members. Inhibitors specific for caspase‐1 and ‐8 however, were less effective in blocking APC cleavage. Mutation of a candidate DNID caspase‐3 target site completely abolished cleavage. This cleavage may be of biological importance since the 90 kDa fragment consists of a sequence that is highly conserved in the human, rat, mouse, Xenopus , and Drosophila APC, although wide sequence divergence is observed in Drosophila immediately carboxy‐terminal to the DNID site. Furthermore, cleavage at this site separates two significant functional domains: an aminoterminal armadillo repeat and an adjacent series of β‐catenin binding sites. Further circumstantial evidence for the significance of APC‐related pathways in apoptosis is provided by the observation that apoptosis also induces cleavage of β‐catenin itself, a protein known to accumulate in cells depleted in functional APC and that appears to link cell–cell signaling to changes in transcription and cell movement.—Webb, S. J., Nicholson, D., Bubb, V. J., Wyllie, A. H. Caspase‐mediated cleavage of APC results in an amino‐terminal fragment with an intact armadillo repeat domain. FASEB J. 13, 339–346 (1999)