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Asporin competes with decorin for collagen binding, binds calcium and promotes osteoblast collagen mineralization

Kalamajski, Sebastian LU ; Aspberg, Anders LU ; Lindblom, Karin LU ; Heinegård, Dick LU and Oldberg, Åke LU (2009) In Biochemical Journal 423. p.53-59
Abstract
The interactions of the ECM (extracellular matrix) protein asporin with ECM components have previously not been investigated. Here, we show that asporin binds collagen type I. This binding is inhibited by recombinant asporin fragment LRR (leucine-rich repeat) 10-12 and by full-length decorin, but not by biglycan. We demonstrate that the polyaspartate domain binds calcium and regulates hydroxyapatite formation in vitro. In the presence of asporin, the number of collagen nodules, and mRNA of osteoblastic markers Osterix and Runx2 were increased. Moreover, decorin or the collagen-binding asporin fragment LRR 10-12 inhibited the pro-osteoblastic activity of full-length asporin. Our results suggest that asporin and decorin compete for binding... (More)
The interactions of the ECM (extracellular matrix) protein asporin with ECM components have previously not been investigated. Here, we show that asporin binds collagen type I. This binding is inhibited by recombinant asporin fragment LRR (leucine-rich repeat) 10-12 and by full-length decorin, but not by biglycan. We demonstrate that the polyaspartate domain binds calcium and regulates hydroxyapatite formation in vitro. In the presence of asporin, the number of collagen nodules, and mRNA of osteoblastic markers Osterix and Runx2 were increased. Moreover, decorin or the collagen-binding asporin fragment LRR 10-12 inhibited the pro-osteoblastic activity of full-length asporin. Our results suggest that asporin and decorin compete for binding to collagen and that the polyaspartate in asporin directly regulates collagen mineralization. Therefore asporin has a role in osteoblast-driven collagen biomineralization activity. We also show that asporin can be expressed in Escherichia coli (Rosettagami (TM)) with correctly positioned cysteine bridges, and a similar system can possibly be used for the expression of other SLRPs (small LRR proteoglycans/proteins). (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
decorin, collagen binding, calcium, asporin, biomineralization, leucine-rich repeat proteoglycan/protein (SLRP), small
in
Biochemical Journal
volume
423
pages
53 - 59
publisher
Portland Press Limited
external identifiers
  • wos:000270420600006
  • scopus:70349772632
ISSN
0264-6021
DOI
10.1042/BJ20090542
language
English
LU publication?
yes
id
1903e5f6-8e33-40d1-a7a7-e25162771bfa (old id 1489802)
date added to LUP
2009-10-21 16:03:50
date last changed
2017-09-24 04:04:00
@article{1903e5f6-8e33-40d1-a7a7-e25162771bfa,
  abstract     = {The interactions of the ECM (extracellular matrix) protein asporin with ECM components have previously not been investigated. Here, we show that asporin binds collagen type I. This binding is inhibited by recombinant asporin fragment LRR (leucine-rich repeat) 10-12 and by full-length decorin, but not by biglycan. We demonstrate that the polyaspartate domain binds calcium and regulates hydroxyapatite formation in vitro. In the presence of asporin, the number of collagen nodules, and mRNA of osteoblastic markers Osterix and Runx2 were increased. Moreover, decorin or the collagen-binding asporin fragment LRR 10-12 inhibited the pro-osteoblastic activity of full-length asporin. Our results suggest that asporin and decorin compete for binding to collagen and that the polyaspartate in asporin directly regulates collagen mineralization. Therefore asporin has a role in osteoblast-driven collagen biomineralization activity. We also show that asporin can be expressed in Escherichia coli (Rosettagami (TM)) with correctly positioned cysteine bridges, and a similar system can possibly be used for the expression of other SLRPs (small LRR proteoglycans/proteins).},
  author       = {Kalamajski, Sebastian and Aspberg, Anders and Lindblom, Karin and Heinegård, Dick and Oldberg, Åke},
  issn         = {0264-6021},
  keyword      = {decorin,collagen binding,calcium,asporin,biomineralization,leucine-rich repeat proteoglycan/protein (SLRP),small},
  language     = {eng},
  pages        = {53--59},
  publisher    = {Portland Press Limited},
  series       = {Biochemical Journal},
  title        = {Asporin competes with decorin for collagen binding, binds calcium and promotes osteoblast collagen mineralization},
  url          = {http://dx.doi.org/10.1042/BJ20090542},
  volume       = {423},
  year         = {2009},
}