| Endosomal-lysosomal proteolysis mediates death signalling by TNFalpha, not by etoposide, in L929 fibrosarcoma cells: evidence for an active role of cathepsin D. | |
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MedLine Citation:
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PMID: 12437111 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In several 'in vitro' models of apoptosis, lysosomal proteolysis has been shown to play an active role in mediating the death signal by cytokines or antiblastic drugs. Depending on the experimental cell model and the cytotoxic stimulus applied, an increased expression and the cytosolic translocation of either cathepsin D or B have been reported in apoptotic cells. We have analysed the involvement of these lysosomal proteases in a canonical apoptotic cell model, namely L929 fibroblasts, in which apoptosis was induced by cytotoxic agents acting through different mechanisms: (i) the cytokine TNFalpha, which triggers the cell suicide via interaction with its membrane receptor, and (ii) the topoisomerase II-inhibitor etoposide (VP16), which directly causes DNA damage. In both cases the activity of cathepsins B and D increased in apoptosing cultures. CA074-Me, a specific inhibitor of cathepsin B, and Leupeptin, a broad inhibitor of serine and cysteine proteases (among which is cathepsin B), did not exert any protection from TNFalpha. In contrast, pre-loading the cells with pepstatin A, a specific inhibitor of cathepsin D, protected L929 cells from TNFalpha cytotoxicity by more than 50%. However, no protection was observed if pepstatin A was added concomitantly with the cytokine. Inhibition of either cathepsin B or D did not impede apoptosis induced by etoposide. Lysosomal integrity was preserved and cathepsin D remained still confined in vesicular structures in apoptotic cells treated with either TNFalpha or etoposide. It follows that proteolysis by cathepsin D is likely to represent an early event in the death pathway triggered by TNFalpha and occurs within the endosomal-lysosomal compartment. |
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Authors:
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Marina Démoz; Roberta Castino; Patrizia Cesaro; Francesco M Baccino; Gabriella Bonelli; Ciro Isidoro |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biological chemistry Volume: 383 ISSN: 1431-6730 ISO Abbreviation: Biol. Chem. Publication Date: 2002 Jul-Aug |
Date Detail:
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Created Date: 2002-11-19 Completed Date: 2003-07-14 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 9700112 Medline TA: Biol Chem Country: Germany |
Other Details:
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Languages: eng Pagination: 1237-48 Citation Subset: IM |
Affiliation:
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Dipartimento di Scienze Mediche, Università A Avogadro, Novara, Italy. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Apoptosis / drug effects* Cathepsin B / drug effects, physiology Cathepsin D / drug effects, physiology Endopeptidases / drug effects, physiology* Endosomes / enzymology Etoposide / pharmacology Fibrosarcoma / pathology Leupeptins / pharmacology Lysosomes / enzymology Mice Pepstatins / pharmacology Signal Transduction / drug effects Tumor Cells, Cultured Tumor Necrosis Factor-alpha / pharmacology* |
| Chemical | |
Reg. No./Substance:
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0/Leupeptins; 0/Pepstatins; 0/Tumor Necrosis Factor-alpha; 24365-47-7/leupeptin; 33419-42-0/Etoposide; 39324-30-6/pepstatin; EC 3.4.-/Endopeptidases; EC 3.4.22.1/Cathepsin B; EC 3.4.23.5/Cathepsin D |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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