Cysteine-Mediated Redox Regulation of Cell Signaling in Chondrocytes Stimulated With Fibronectin Fragments

Arthritis Rheumatol. 2016 Jan;68(1):117-26. doi: 10.1002/art.39326.


Objective: Oxidative posttranslational modifications of intracellular proteins can potentially regulate signaling pathways relevant to cartilage destruction in arthritis. In this study, oxidation of cysteine residues to form sulfenic acid (S-sulfenylation) was examined in osteoarthritic (OA) chondrocytes and investigated in normal chondrocytes as a mechanism by which fragments of fibronectin (FN-f) stimulate chondrocyte catabolic signaling.

Methods: Chondrocytes isolated from OA and normal human articular cartilage were analyzed using analogs of dimedone that specifically and irreversibly react with protein S-sulfenylated cysteines. Global S-sulfenylation was measured in cell lysates with and without FN-f stimulation by immunoblotting and in fixed cells by confocal microscopy. S-sulfenylation in specific proteins was identified by mass spectroscopy and confirmed by immunoblotting. Src activity was measured in live cells using a fluorescence resonance energy transfer biosensor.

Results: Proteins in chondrocytes isolated from OA cartilage were found to have elevated basal levels of S-sulfenylation relative to those of chondrocytes from normal cartilage. Treatment of normal chondrocytes with FN-f induced increased levels of S-sulfenylation in multiple proteins, including the tyrosine kinase Src. FN-f treatment also increased the levels of Src activity. Pretreatment with dimedone to alter S-sulfenylation function or with Src kinase inhibitors inhibited FN-f-induced production of matrix metalloproteinase 13.

Conclusion: These results demonstrate for the first time the presence of oxidative posttranslational modification of proteins in human articular chondrocytes by S-sulfenylation. Due to the ability to regulate the activity of a number of cell signaling pathways, including catabolic mediators induced by fibronectin fragments, S-sulfenylation may contribute to cartilage destruction in OA and warrants further investigation.

Publication types

  • Historical Article
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cartilage, Articular / cytology*
  • Case-Control Studies
  • Chondrocytes / drug effects
  • Chondrocytes / metabolism*
  • Cyclohexanones / pharmacology
  • Cysteine / metabolism*
  • Female
  • Fibronectins / pharmacology
  • History, Ancient
  • Humans
  • Immunoblotting
  • Mass Spectrometry
  • Matrix Metalloproteinase 13 / drug effects
  • Matrix Metalloproteinase 13 / metabolism
  • Microscopy, Confocal
  • Middle Aged
  • Osteoarthritis / metabolism*
  • Oxidation-Reduction*
  • Peptide Fragments / pharmacology
  • Protein Processing, Post-Translational
  • Signal Transduction
  • Sulfenic Acids / metabolism*
  • src-Family Kinases / drug effects
  • src-Family Kinases / metabolism*


  • Cyclohexanones
  • Fibronectins
  • Peptide Fragments
  • Sulfenic Acids
  • dimedone
  • src-Family Kinases
  • MMP13 protein, human
  • Matrix Metalloproteinase 13
  • Cysteine