Proteolytic cleavage of Livin (ML-IAP) in apoptotic melanoma cells potentially mediated by a non-canonical caspase
| Autor: | Tong Liu, Ray M. Lee, Douglas Grossman, Diana L. Biddle, Deepak Raj, Hui Yan, Brook Brouha |
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| Jazyk: | angličtina |
| Rok vydání: | 2006 |
| Předmět: |
Proteases
Apoptosis Dermatology Cleavage (embryo) Inhibitor of apoptosis Biochemistry Article Amino Acid Chloromethyl Ketones Inhibitor of Apoptosis Proteins Substrate Specificity Mitochondrial Proteins Endopeptidases Protein Interaction Mapping medicine Humans Protease Inhibitors Molecular Biology Melanoma Caspase Adaptor Proteins Signal Transducing Serine protease Cisplatin biology Serine Endopeptidases High-Temperature Requirement A Serine Peptidase 2 Molecular biology Caspase Inhibitors Neoplasm Proteins Amino Acid Substitution Cell culture Caspases Mutation biology.protein Melanocytes medicine.drug |
| Popis: | Summary Background Several inhibitor of apoptosis proteins (IAPs) are cleaved during apoptosis. Studies of the melanoma-associated IAP (ML-IAP) Livin, using recombinant molecules, have implicated both caspases 3/7 and the serine protease Omi/HtrA2 in its proteolytic cleavage. Objective To characterize the apoptotic cleavage of Livin in melanocytic cells, and evaluate the role of known proteases. Methods We assessed the capacity of a variety of stimuli to induce Livin cleavage in human melanoma cell lines and normal human melanocytes. The role of caspases and Omi was examined using caspase inhibitors and RNAi, respectively. A potential caspase substrate was further examined by site-directed mutagenesis. Deletion mapping was used to identify the cleavage site. Results Livin cleavage was observed in multiple human melanoma cell lines in response to a variety of apoptotic stimuli (UVB, 4-TBP, cisplatin, TNF, Bax), and not affected by the addition of various protease inhibitors or RNAi-mediated silencing of Omi/HtrA2. Livin cleavage induced by 4-TBP, but not UVB or cisplatin, was blocked by the pan-caspase inhibitor zVAD-fmk. Mutation of Asp 52 to Glu in Livin did not affect cleavage, while either mutation of Asp 52 to Ala, deletion of Asp 52 , or deletion of the adjacent region (residues 53–61) abrogated cleavage. Conclusion Livin cleavage, induced by multiple apoptotic stimuli in melanoma cells, likely occurs in an Omi-independent fashion at residue 52 within its potential caspase substrate (DHVD 52 ). However, relative insensitivity of the apoptotic cleavage to zVAD-fmk, or Asp 52 to Glu mutation, suggests the involvement of a non-canonical caspase. |
| Databáze: | OpenAIRE |
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