title: Caspase-dependent cleavage of ErbB-2 by geldanamycin and staurosporin.
abstract: The geldanamycin-induced degradation of ErbB-2 produces a 23-kDa carboxyl-terminal fragment, which has been isolated and subjected to amino-terminal microsequencing. The obtained sequence indicates that the amino terminus of this fragment corresponds to Gly-1126 of ErbB-2. Analysis of the residues immediately before Gly-1126 suggests that cleavage may involve caspase activity. Site-directed mutagenesis of Asp-1125 in ErbB-2 prevents geldanamycin-provoked formation of the 23-kDa fragment, consistent with the requirement of this residue for caspase-dependent cleavage in known substrates. Also, the addition of the pan-caspase inhibitor Z-VAD-FMK blocks formation of the 23-kDa ErbB-2 fragment in cells exposed to geldanamycin. Interestingly, staurosporin and curcumin are also shown to provoke the degradation of ErbB-2 with formation of the 23-kDa carboxyl-terminal fragment. The generation of this fragment by staurosporin or curcumin is likewise blocked by caspase inhibition. Caspase inhibition does not prevent accelerated degradation of the 185-kDa native ErbB-2 in geldanamycin-treated cells but does significantly prevent staurosporin-stimulated metabolic loss of ErbB-2.
authors.affiliation: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
authors.forename: O
authors.initials: O
authors.lastname: Tikhomirov
authors.forename: G
authors.initials: G
authors.lastname: Carpenter
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D016227:Benzoquinones; D019556:COS Cells; D061945:Caspase Inhibitors; D020169:Caspases / Q000737:chemistry*; D003474:Curcumin / Q000494:pharmacology; D003593:Cytoplasm / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005998:Glycine / Q000737:chemistry; D006801:Humans; D015151:Immunoblotting; D047029:Lactams, Macrocyclic; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011809:Quinones / Q000494:pharmacology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D019311:Staurosporine / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D016227:Benzoquinones; D061945:Caspase Inhibitors; D020169:Caspases; D003474:Curcumin; D004791:Enzyme Inhibitors; D005998:Glycine; D047029:Lactams, Macrocyclic; D011809:Quinones; D018719:Erb-b2 Receptor Tyrosine Kinases; D019311:Staurosporine; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C001277:geldanamycin