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Cathepsin g Degrades Both Glycosylated and Unglycosylated Regions of Lubricin, a Synovial Mucin

Huang, Shan ; Thomsson, Kristina A. ; Jin, Chunsheng ; Alweddi, Sally ; Struglics, André LU ; Rolfson, Ola ; Björkman, Lena I. ; Kalamajski, Sebastian LU ; Schmidt, Tannin A. and Jay, Gregory D. , et al. (2020) In Scientific Reports 10.
Abstract

Lubricin (PRG4) is a mucin type protein that plays an important role in maintaining normal joint function by providing lubrication and chondroprotection. Improper lubricin modification and degradation has been observed in idiopathic osteoarthritis (OA), while the detailed mechanism still remains unknown. We hypothesized that the protease cathepsin G (CG) may participate in degrading lubricin in synovial fluid (SF). The presence of endogenous CG in SF was confirmed in 16 patients with knee OA. Recombinant human lubricin (rhPRG4) and native lubricin purified from the SF of patients were incubated with exogenous CG and lubricin degradation was monitored using western blot, staining by Coomassie or Periodic Acid-Schiff base in gels, and... (More)

Lubricin (PRG4) is a mucin type protein that plays an important role in maintaining normal joint function by providing lubrication and chondroprotection. Improper lubricin modification and degradation has been observed in idiopathic osteoarthritis (OA), while the detailed mechanism still remains unknown. We hypothesized that the protease cathepsin G (CG) may participate in degrading lubricin in synovial fluid (SF). The presence of endogenous CG in SF was confirmed in 16 patients with knee OA. Recombinant human lubricin (rhPRG4) and native lubricin purified from the SF of patients were incubated with exogenous CG and lubricin degradation was monitored using western blot, staining by Coomassie or Periodic Acid-Schiff base in gels, and with proteomics. Full length lubricin (∼300 kDa), was efficiently digested with CG generating a 25-kDa protein fragment, originating from the densely glycosylated mucin domain (∼250 kDa). The 25-kDa fragment was present in the SF from OA patients, and the amount was increased after incubation with CG. A CG digest of rhPRG4 revealed 135 peptides and 72 glycopeptides, and confirmed that the protease could cleave in all domains of lubricin, including the mucin domain. Our results suggest that synovial CG may take part in the degradation of lubricin, which could affect the pathological decrease of the lubrication in degenerative joint disease.

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organization
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type
Contribution to journal
publication status
published
subject
in
Scientific Reports
volume
10
article number
4215
publisher
Nature Publishing Group
external identifiers
  • pmid:32144329
  • scopus:85081531357
ISSN
2045-2322
DOI
10.1038/s41598-020-61161-5
language
English
LU publication?
yes
id
098f68a1-e94d-464c-92af-bb4afd2901cd
date added to LUP
2020-03-29 17:26:54
date last changed
2024-03-04 15:28:41
@article{098f68a1-e94d-464c-92af-bb4afd2901cd,
  abstract     = {{<p>Lubricin (PRG4) is a mucin type protein that plays an important role in maintaining normal joint function by providing lubrication and chondroprotection. Improper lubricin modification and degradation has been observed in idiopathic osteoarthritis (OA), while the detailed mechanism still remains unknown. We hypothesized that the protease cathepsin G (CG) may participate in degrading lubricin in synovial fluid (SF). The presence of endogenous CG in SF was confirmed in 16 patients with knee OA. Recombinant human lubricin (rhPRG4) and native lubricin purified from the SF of patients were incubated with exogenous CG and lubricin degradation was monitored using western blot, staining by Coomassie or Periodic Acid-Schiff base in gels, and with proteomics. Full length lubricin (∼300 kDa), was efficiently digested with CG generating a 25-kDa protein fragment, originating from the densely glycosylated mucin domain (∼250 kDa). The 25-kDa fragment was present in the SF from OA patients, and the amount was increased after incubation with CG. A CG digest of rhPRG4 revealed 135 peptides and 72 glycopeptides, and confirmed that the protease could cleave in all domains of lubricin, including the mucin domain. Our results suggest that synovial CG may take part in the degradation of lubricin, which could affect the pathological decrease of the lubrication in degenerative joint disease.</p>}},
  author       = {{Huang, Shan and Thomsson, Kristina A. and Jin, Chunsheng and Alweddi, Sally and Struglics, André and Rolfson, Ola and Björkman, Lena I. and Kalamajski, Sebastian and Schmidt, Tannin A. and Jay, Gregory D. and Krawetz, Roman and Karlsson, Niclas G. and Eisler, Thomas}},
  issn         = {{2045-2322}},
  language     = {{eng}},
  month        = {{03}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Scientific Reports}},
  title        = {{Cathepsin g Degrades Both Glycosylated and Unglycosylated Regions of Lubricin, a Synovial Mucin}},
  url          = {{http://dx.doi.org/10.1038/s41598-020-61161-5}},
  doi          = {{10.1038/s41598-020-61161-5}},
  volume       = {{10}},
  year         = {{2020}},
}