Document Detail

Intra- and extracellular regulation of activity and processing of legumain by cystatin E/M.
MedLine Citation:
PMID:  22902879     Owner:  NLM     Status:  Publisher    
Legumain, an asparaginyl endopeptidase, is up-regulated in tumour and tumour-associated cells, and is linked to the processing of cathepsin B, L, and proMMP-2. Although legumain is mainly localized to the endosomal/lysosomal compartments, legumain has been reported to be localized extracellularly in the tumour microenvironment and associated with extracellular matrix and cell surfaces. The most potent endogenous inhibitor of legumain is cystatin E/M, which is a secreted protein synthesised with an export signal. Therefore, we investigated the cellular interplay between legumain and cystatin E/M. As a cell model, HEK293 cells were transfected with legumain cDNA, cystatin E/M cDNA, or both, and over-expressing monoclonal cell lines were selected (termed M38L, M4C, and M3CL, respectively). Secretion of prolegumain from M38L cells was inhibited by treatment with brefeldin A, whereas bafilomycin A1 enhanced the secretion. Cellular processing of prolegumain to the 46 and 36 kDa enzymatically active forms was reduced by treatment with either substance alone. M38L cells showed increased, but M4C cells decreased, cathepsin L processing suggesting a crucial involvement of legumain activity. Furthermore, we observed internalization of cystatin E/M and subsequently decreased intracellular legumain activity. Also, prolegumain was shown to internalize followed by increased intracellular legumain processing and activation. In addition, in M4C cells incomplete processing of the internalized prolegumain was observed, as well as nuclear localized cystatin E/M. Furthermore, auto-activation of secreted prolegumain was inhibited by cystatin E/M, which for the first time shows a regulatory role of cystatin E/M in controlling both intra- and extracellular legumain activity.
Robert Smith; Harald T Johansen; Hilde Nilsen; Mads H Haugen; Solveig J Pettersen; Gunhild M Mælandsmo; Magnus Abrahamson; Rigmor Solberg
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-8-10
Journal Detail:
Title:  Biochimie     Volume:  -     ISSN:  1638-6183     ISO Abbreviation:  Biochimie     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-8-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  1264604     Medline TA:  Biochimie     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 Elsevier Masson SAS. All rights reserved.
Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Norway.
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