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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
6 Pt 1
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pubmed:dateCreated |
1990-2-12
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pubmed:abstractText |
To examine the effects of cysteine protease inhibitors on cathepsin D intracellular transport, proteolytic processing, and secretion, primary cultures of rabbit cardiac fibroblasts were grown to confluence and exposed (24 h) to media containing leupeptin (0-10 mM), E 64 (0-10 mM), or chloroquine (0-50 microM). Cathepsin D maturation was then evaluated in pulse-chase biosynthetic labeling experiments. None of the three agents affected the charge modification of procathepsin D (Mr 53,000) within the Golgi apparatus. However, all three agents interfered with the subsequent proteolytic processing of procathepsin D isoforms to active cathepsin D (Mr 48,000). Both leupeptin and E 64 caused the intracellular accumulation of large amounts of a Mr 51,000 processing intermediate (not detectable in control fibroblasts). Trace amounts of this intermediate were also detected in chloroquine-treated cells. Combined activity assay and radioimmunoassay of cell lysates indicated that this partially processed form of cathepsin D possessed proteolytic activity. Whereas low medium concentrations of leupeptin (10-100 microM) but not E 64 appeared to stimulate procathepsin D secretion, neither agent appeared to have a major effect on the rate of proenzyme secretion at doses required to inhibit proteolytic maturation (1-10 mM). Furthermore, pretreatment of cells with 10 mM leupeptin appeared only to delay, but not prevent, the intracellular transport of cathepsin D to lysosomes. In contrast, chloroquine increased procathepsin D secretion in a dose-dependent manner, diverting the majority of newly synthesized procathepsin D from the intracellular protease(s) responsible for proteolytic processing. These results suggest that cysteine proteases participate in the proteolytic maturation of procathepsin D during the transport of newly synthesized enzyme to lysosomes, but cysteine protease-mediated proteolytic processing is not required for cathepsin D activation or lysosomal translocation.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Cathepsin D,
http://linkedlifedata.com/resource/pubmed/chemical/Chloroquine,
http://linkedlifedata.com/resource/pubmed/chemical/Cysteine Proteinase Inhibitors,
http://linkedlifedata.com/resource/pubmed/chemical/E 64,
http://linkedlifedata.com/resource/pubmed/chemical/Leucine,
http://linkedlifedata.com/resource/pubmed/chemical/Leupeptins,
http://linkedlifedata.com/resource/pubmed/chemical/Methionine,
http://linkedlifedata.com/resource/pubmed/chemical/Sulfur Radioisotopes
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pubmed:status |
MEDLINE
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pubmed:month |
Dec
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pubmed:issn |
0002-9513
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
257
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
C1069-79
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:2610247-Animals,
pubmed-meshheading:2610247-Cathepsin D,
pubmed-meshheading:2610247-Cells, Cultured,
pubmed-meshheading:2610247-Chloroquine,
pubmed-meshheading:2610247-Cysteine Proteinase Inhibitors,
pubmed-meshheading:2610247-Fibroblasts,
pubmed-meshheading:2610247-Kinetics,
pubmed-meshheading:2610247-Leucine,
pubmed-meshheading:2610247-Leupeptins,
pubmed-meshheading:2610247-Methionine,
pubmed-meshheading:2610247-Myocardium,
pubmed-meshheading:2610247-Protein Processing, Post-Translational,
pubmed-meshheading:2610247-Rabbits,
pubmed-meshheading:2610247-Sulfur Radioisotopes
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pubmed:year |
1989
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pubmed:articleTitle |
Effects of cysteine protease inhibitors on rabbit cathepsin D maturation.
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pubmed:affiliation |
Department of Medicine, Loyola University, Stritch School of Medicine, Maywood 60153.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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