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Cystatins - Extra- and Intracellular Cysteine Protease Inhibitors: High-level Secretion and Uptake of Cystatin C in Human Neuroblastoma Cells.

Wallin, Hanna LU ; Bjarnadottir, Maria; Vogel, Lotte K; Wasselius, Johan LU ; Ekström, Ulf LU and Abrahamson, Magnus LU (2010) In Biochimie 92. p.1625-1634
Abstract
Cystatins are present in mammals, birds, fish, insects, plants, fungi and protozoa and constitute a large protein family, with most members sharing a cysteine protease inhibitory function. In humans 12 functional cystatins exist, forming three groups based on molecular organisation and distribution in the organism. The type 1 cystatins (A and B) are known as intracellular, type 2 cystatins (C, D, E/M, F, G, S, SN and SA) extracellular and type 3 cystatins (L- and H-kininogen) intravascular proteins. The present paper is focused on the human cystatins and especially those of type 2, which are directed (with signal peptides) for cellular export following translation. Results indicating existence of systems for significant internalisation of... (More)
Cystatins are present in mammals, birds, fish, insects, plants, fungi and protozoa and constitute a large protein family, with most members sharing a cysteine protease inhibitory function. In humans 12 functional cystatins exist, forming three groups based on molecular organisation and distribution in the organism. The type 1 cystatins (A and B) are known as intracellular, type 2 cystatins (C, D, E/M, F, G, S, SN and SA) extracellular and type 3 cystatins (L- and H-kininogen) intravascular proteins. The present paper is focused on the human cystatins and especially those of type 2, which are directed (with signal peptides) for cellular export following translation. Results indicating existence of systems for significant internalisation of type 2 cystatins from the extracellular to intracellular compartments are reviewed. Data showing that human neuroblastoma cell lines generally secrete high levels, but also contain high amounts of cystatin C are presented. Culturing of these cells in medium containing cystatin C at concentrations found in body fluids resulted in increased intracellular cystatin C, as a result of an uptake process. At immunofluorescence cytochemistry a pronounced vesicular cystatin C staining was observed. The simplistic denotation of the type 2 cystatins as extracellular inhibitors is thus challenged, and possible biological functions of the internalised cystatins are discussed. To illustrate the special case of high cellular cystatin content seen in cells of patients with hereditary cystatin C amyloid angiopathy, expression vectors for wild-type and L68Q mutated cystatin C were used to transfect SK-N-BE(2) cells. Clones overexpressing the two variants showed increased secreted levels of cystatin C. Within the cells the L68Q variant appeared to mainly localise to the endoplasmic reticulum rather than to acidic vesicular organelles, indicating limitations in the transport out from the cell rather than increased uptake as explanation for the elevated cellular cystatin levels seen in hereditary cystatin C amyloid angiopathy. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochimie
volume
92
pages
1625 - 1634
publisher
Elsevier
external identifiers
  • wos:000284717300014
  • pmid:20800088
  • scopus:78149361024
ISSN
1638-6183
DOI
10.1016/j.biochi.2010.08.011
language
English
LU publication?
yes
id
0eb7b6e5-aa8b-42c4-b486-e6af12681b09 (old id 1664946)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/20800088?dopt=Abstract
date added to LUP
2010-09-03 10:50:04
date last changed
2018-06-17 04:57:49
@article{0eb7b6e5-aa8b-42c4-b486-e6af12681b09,
  abstract     = {Cystatins are present in mammals, birds, fish, insects, plants, fungi and protozoa and constitute a large protein family, with most members sharing a cysteine protease inhibitory function. In humans 12 functional cystatins exist, forming three groups based on molecular organisation and distribution in the organism. The type 1 cystatins (A and B) are known as intracellular, type 2 cystatins (C, D, E/M, F, G, S, SN and SA) extracellular and type 3 cystatins (L- and H-kininogen) intravascular proteins. The present paper is focused on the human cystatins and especially those of type 2, which are directed (with signal peptides) for cellular export following translation. Results indicating existence of systems for significant internalisation of type 2 cystatins from the extracellular to intracellular compartments are reviewed. Data showing that human neuroblastoma cell lines generally secrete high levels, but also contain high amounts of cystatin C are presented. Culturing of these cells in medium containing cystatin C at concentrations found in body fluids resulted in increased intracellular cystatin C, as a result of an uptake process. At immunofluorescence cytochemistry a pronounced vesicular cystatin C staining was observed. The simplistic denotation of the type 2 cystatins as extracellular inhibitors is thus challenged, and possible biological functions of the internalised cystatins are discussed. To illustrate the special case of high cellular cystatin content seen in cells of patients with hereditary cystatin C amyloid angiopathy, expression vectors for wild-type and L68Q mutated cystatin C were used to transfect SK-N-BE(2) cells. Clones overexpressing the two variants showed increased secreted levels of cystatin C. Within the cells the L68Q variant appeared to mainly localise to the endoplasmic reticulum rather than to acidic vesicular organelles, indicating limitations in the transport out from the cell rather than increased uptake as explanation for the elevated cellular cystatin levels seen in hereditary cystatin C amyloid angiopathy.},
  author       = {Wallin, Hanna and Bjarnadottir, Maria and Vogel, Lotte K and Wasselius, Johan and Ekström, Ulf and Abrahamson, Magnus},
  issn         = {1638-6183},
  language     = {eng},
  pages        = {1625--1634},
  publisher    = {Elsevier},
  series       = {Biochimie},
  title        = {Cystatins - Extra- and Intracellular Cysteine Protease Inhibitors: High-level Secretion and Uptake of Cystatin C in Human Neuroblastoma Cells.},
  url          = {http://dx.doi.org/10.1016/j.biochi.2010.08.011},
  volume       = {92},
  year         = {2010},
}