Abstract | BACKGROUND: 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 Asp52 to Glu in Livin did not affect cleavage, while either mutation of Asp52 to Ala, deletion of Asp52, 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 (DHVD52). However, relative insensitivity of the apoptotic cleavage to zVAD-fmk, or Asp52 to Glu mutation, suggests the involvement of a non-canonical caspase.
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Authors | Hui Yan, Brook Brouha, Tong Liu, Deepak Raj, Diana Biddle, Ray Lee, Douglas Grossman |
Journal | Journal of dermatological science
(J Dermatol Sci)
Vol. 43
Issue 3
Pg. 189-200
(Sep 2006)
ISSN: 0923-1811 [Print] Netherlands |
PMID | 16806840
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
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Chemical References |
- Adaptor Proteins, Signal Transducing
- Amino Acid Chloromethyl Ketones
- BIRC7 protein, human
- Caspase Inhibitors
- Inhibitor of Apoptosis Proteins
- Mitochondrial Proteins
- Neoplasm Proteins
- Protease Inhibitors
- benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
- Endopeptidases
- Serine Endopeptidases
- HTRA2 protein, human
- High-Temperature Requirement A Serine Peptidase 2
- Caspases
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Topics |
- Adaptor Proteins, Signal Transducing
(genetics, metabolism)
- Amino Acid Chloromethyl Ketones
(pharmacology)
- Amino Acid Substitution
- Apoptosis
- Caspase Inhibitors
- Caspases
(metabolism)
- Endopeptidases
(drug effects, metabolism)
- High-Temperature Requirement A Serine Peptidase 2
- Humans
- Inhibitor of Apoptosis Proteins
(genetics, metabolism)
- Melanocytes
(metabolism)
- Melanoma
(metabolism)
- Mitochondrial Proteins
- Mutation
- Neoplasm Proteins
(genetics, metabolism)
- Protease Inhibitors
(pharmacology)
- Protein Interaction Mapping
- Serine Endopeptidases
(genetics, metabolism)
- Substrate Specificity
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