Cartilage oligomeric matrix protein forms protein complexes with synovial lubricin via non-covalent and covalent interactions

S. A. Flowers, S. Kalamajski, Liaqat Ali, L. I. Björkman, J. R. Raj, A. Aspberg, N. G. Karlsson, C. Jin

Research output: Contribution to journalArticle

Abstract

Objective Understanding the cartilage surface structure, lost in arthritic disease, is essential for developing strategies to effectively restore it. Given that adherence of the lubricating protein, lubricin, to the cartilage surface is critical for boundary lubrication, an interaction with cartilage oligomeric matrix protein (COMP) was investigated. COMP, an abundant cartilage protein, is known to be important for matrix formation. Design Synovial fluid (SF) from arthritic patients was used to detect possible COMP–lubricin complexes by immunological methods. Recombinant (RC) COMP and lubricin fragments were expressed to characterize this bonding and mass spectrometry employed to specifically identify the cysteines involved in inter-protein disulfide bonds. Results COMP–lubricin complexes were identified in the SF of arthritic patients by Western blot, co-immunoprecipitation and sandwich ELISA. RC fragment solid-phase binding assays showed that the C-terminal (amino acids (AA) 518-757) of COMP bound non-covalently to the N-terminal of lubricin (AA 105-202). Mass spectrometry determined that although cysteines throughout COMP were involved in binding with lubricin, the cysteines in lubricin were primarily focused to an N-terminal region (AA 64-86). The close proximity of the non-covalent and disulfide binding domains on lubricin suggest a two-step mechanism to strongly bind lubricin to COMP. Conclusion These data demonstrate that lubricin forms a complex network with COMP involving both non-covalent and covalent bonds. This complex between lubricin and the cartilage protein COMP can be identified in the SF of patients with arthritis conditions including osteoarthritis (OA) and rheumatoid arthritis (RA).

Original languageEnglish (US)
Pages (from-to)1496-1504
Number of pages9
JournalOsteoarthritis and Cartilage
Volume25
Issue number9
DOIs
StatePublished - Sep 1 2017

Fingerprint

Cartilage Oligomeric Matrix Protein
Cartilage
Proteins
Arthritis
Synovial Fluid
Cysteine
Amino acids
Amino Acids
Disulfides
Mass Spectrometry
Mass spectrometry
Lubrication
Fluids
lubricin
Immunoprecipitation
Recombinant Proteins
Osteoarthritis
Covalent bonds
Rheumatoid Arthritis
Complex networks

Keywords

  • Boundary lubrication
  • Cartilage degradation
  • Cartilage oligomeric matrix protein
  • Lubricin
  • O-linked glycoproteins
  • Proteomics

ASJC Scopus subject areas

  • Rheumatology
  • Biomedical Engineering
  • Orthopedics and Sports Medicine

Cite this

Cartilage oligomeric matrix protein forms protein complexes with synovial lubricin via non-covalent and covalent interactions. / Flowers, S. A.; Kalamajski, S.; Ali, Liaqat; Björkman, L. I.; Raj, J. R.; Aspberg, A.; Karlsson, N. G.; Jin, C.

In: Osteoarthritis and Cartilage, Vol. 25, No. 9, 01.09.2017, p. 1496-1504.

Research output: Contribution to journalArticle

Flowers, S. A. ; Kalamajski, S. ; Ali, Liaqat ; Björkman, L. I. ; Raj, J. R. ; Aspberg, A. ; Karlsson, N. G. ; Jin, C. / Cartilage oligomeric matrix protein forms protein complexes with synovial lubricin via non-covalent and covalent interactions. In: Osteoarthritis and Cartilage. 2017 ; Vol. 25, No. 9. pp. 1496-1504.
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abstract = "Objective Understanding the cartilage surface structure, lost in arthritic disease, is essential for developing strategies to effectively restore it. Given that adherence of the lubricating protein, lubricin, to the cartilage surface is critical for boundary lubrication, an interaction with cartilage oligomeric matrix protein (COMP) was investigated. COMP, an abundant cartilage protein, is known to be important for matrix formation. Design Synovial fluid (SF) from arthritic patients was used to detect possible COMP–lubricin complexes by immunological methods. Recombinant (RC) COMP and lubricin fragments were expressed to characterize this bonding and mass spectrometry employed to specifically identify the cysteines involved in inter-protein disulfide bonds. Results COMP–lubricin complexes were identified in the SF of arthritic patients by Western blot, co-immunoprecipitation and sandwich ELISA. RC fragment solid-phase binding assays showed that the C-terminal (amino acids (AA) 518-757) of COMP bound non-covalently to the N-terminal of lubricin (AA 105-202). Mass spectrometry determined that although cysteines throughout COMP were involved in binding with lubricin, the cysteines in lubricin were primarily focused to an N-terminal region (AA 64-86). The close proximity of the non-covalent and disulfide binding domains on lubricin suggest a two-step mechanism to strongly bind lubricin to COMP. Conclusion These data demonstrate that lubricin forms a complex network with COMP involving both non-covalent and covalent bonds. This complex between lubricin and the cartilage protein COMP can be identified in the SF of patients with arthritis conditions including osteoarthritis (OA) and rheumatoid arthritis (RA).",
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AU - Flowers, S. A.

AU - Kalamajski, S.

AU - Ali, Liaqat

AU - Björkman, L. I.

AU - Raj, J. R.

AU - Aspberg, A.

AU - Karlsson, N. G.

AU - Jin, C.

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N2 - Objective Understanding the cartilage surface structure, lost in arthritic disease, is essential for developing strategies to effectively restore it. Given that adherence of the lubricating protein, lubricin, to the cartilage surface is critical for boundary lubrication, an interaction with cartilage oligomeric matrix protein (COMP) was investigated. COMP, an abundant cartilage protein, is known to be important for matrix formation. Design Synovial fluid (SF) from arthritic patients was used to detect possible COMP–lubricin complexes by immunological methods. Recombinant (RC) COMP and lubricin fragments were expressed to characterize this bonding and mass spectrometry employed to specifically identify the cysteines involved in inter-protein disulfide bonds. Results COMP–lubricin complexes were identified in the SF of arthritic patients by Western blot, co-immunoprecipitation and sandwich ELISA. RC fragment solid-phase binding assays showed that the C-terminal (amino acids (AA) 518-757) of COMP bound non-covalently to the N-terminal of lubricin (AA 105-202). Mass spectrometry determined that although cysteines throughout COMP were involved in binding with lubricin, the cysteines in lubricin were primarily focused to an N-terminal region (AA 64-86). The close proximity of the non-covalent and disulfide binding domains on lubricin suggest a two-step mechanism to strongly bind lubricin to COMP. Conclusion These data demonstrate that lubricin forms a complex network with COMP involving both non-covalent and covalent bonds. This complex between lubricin and the cartilage protein COMP can be identified in the SF of patients with arthritis conditions including osteoarthritis (OA) and rheumatoid arthritis (RA).

AB - Objective Understanding the cartilage surface structure, lost in arthritic disease, is essential for developing strategies to effectively restore it. Given that adherence of the lubricating protein, lubricin, to the cartilage surface is critical for boundary lubrication, an interaction with cartilage oligomeric matrix protein (COMP) was investigated. COMP, an abundant cartilage protein, is known to be important for matrix formation. Design Synovial fluid (SF) from arthritic patients was used to detect possible COMP–lubricin complexes by immunological methods. Recombinant (RC) COMP and lubricin fragments were expressed to characterize this bonding and mass spectrometry employed to specifically identify the cysteines involved in inter-protein disulfide bonds. Results COMP–lubricin complexes were identified in the SF of arthritic patients by Western blot, co-immunoprecipitation and sandwich ELISA. RC fragment solid-phase binding assays showed that the C-terminal (amino acids (AA) 518-757) of COMP bound non-covalently to the N-terminal of lubricin (AA 105-202). Mass spectrometry determined that although cysteines throughout COMP were involved in binding with lubricin, the cysteines in lubricin were primarily focused to an N-terminal region (AA 64-86). The close proximity of the non-covalent and disulfide binding domains on lubricin suggest a two-step mechanism to strongly bind lubricin to COMP. Conclusion These data demonstrate that lubricin forms a complex network with COMP involving both non-covalent and covalent bonds. This complex between lubricin and the cartilage protein COMP can be identified in the SF of patients with arthritis conditions including osteoarthritis (OA) and rheumatoid arthritis (RA).

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