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The influence of differential processing of procathepsin H on its aminopeptidase activity, secretion and subcellular localization in human cell lines.
MedLine Citation:
PMID:  22704610     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Cathepsin H is a unique member of the cysteine cathepsins that acts primarily as an aminopeptidase. Like other cysteine cathepsins, it is synthesized as an inactive precursor and activated by proteolytic removal of its propeptide. Here we demonstrate that, in human cells, the processing of the propeptide is an autocatalytic, multistep process proceeding from an inactive 41kDa pro-form, through a 30kDa intermediate form, to the 28kDa mature form. Tyr87P and Gly90P were identified as the two major endopeptidase cleavage sites, converting the 30kDa form into the mature 28kDa form. The level of processing differs significantly in different human cell lines. In monocyte-derived macrophages U937 and prostate cancer cells PC-3, the 28kDa form is predominant, whereas in osteoblasts HOS the processing from the 30kDa form to the 28kDa form is significantly lower. The aminopeptidase activity of the enzyme and its subcellular localization are independent of the product, however the 30kDa form was not secreted in HOS cells. The activity of the resulting cathepsin H in U937 cells was significantly lower than that in HOS cells, presumably due to the high levels of endogenous cysteine protease inhibitor cystatin F present specifically in this cell line. These results provide an insight into the dependence of human cathepsin H processing and regulation on cell type.
Authors:
Matija Rojnik; Zala R Jevnikar; Bojan Doljak; Samo Turk; Nace Zidar; Janko Kos
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-6-13
Journal Detail:
Title:  European journal of cell biology     Volume:  -     ISSN:  1618-1298     ISO Abbreviation:  -     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-6-18     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7906240     Medline TA:  Eur J Cell Biol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier GmbH.
Affiliation:
Department of Pharmaceutical Biology, Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, SI-1000 Ljubljana, Slovenia.
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