Regulation of Mitogen-Activated Protein Kinases (MAPK) and Matrix Metalloproteinases (MMP) by Reactive Oxygen Species (ROS)

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  • May 16, 2019
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  • Shwartz, Sophia
    • Affiliation: School of Medicine, Thurston Arthritis Research Center
Abstract
  • Osteoarthritis (OA) is a chronic, disabling disease involving articular joints and is characterized by cartilage destruction. Pathological changes associated with osteoarthritis have been attributed to the activation of MAP kinase (MAPK) pathways by reactive oxygen species (ROS) in response to catabolic stimuli. Additionally, cartilage cells, also known as chondrocytes, produce nitric oxide (NO), a ROS. NO has been shown to readily interact with superoxide to form peroxynitrite, which in turn, is thought to mediate cartilage damage. Additionally, NO is thought to promote signals that increase matrix metalloproteinase (MMP) production, which is implicated in the breakdown of the extracellular matrix of cartilage. The purpose of this study was to observe how ROS regulate cellular mechanisms of inflammation and cartilage degradation in osteoarthritis. Chondrocytes isolated from articular cartilage were treated with endotoxin-free recombinant human fibronectin fragment (Fnf) (42 kD), recombinant human interleukin-1 (IL-1), DMNQ, or menadione. Fnf and IL-1 elicited increased levels of NO in the media while DMNQ and menadione did not. DMNQ and menadione elicited increased hydrogen peroxide (H2O2) levels in media but Fnf and IL-1 did not. Pre-treatment with the antioxidant MnTBAP reduced Fnf and IL-1-associated NO production and decreased MMP-13 production. These results suggest that NO and/or peroxynitrite may play a role in contributing to the production of degradative factors such as MMP-13. Chondrocytes were also treated with H2O2 in a dose curve 0.5 to 50 μM or Fnf, a physiological source of H2O2. Phosphorylation of MAPKs (JNK, ERK, p38) was measured in cell lysates using phospho-antibodies and oxidation was measured by probing BIAM pulled-down proteins with antibodies to MAPKs. Low levels of ROS were required for JNK activation and both low and high levels activated p38. ERK was less sensitive to oxidation than JNK but was more sensitive than p38. This suggests that differential activation of MAPKs by ROS levels represents an additional layer of regulation that distinguishes stress and non-stress signaling.
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  • In Copyright
Advisor
  • Loeser, Richard
Degree
  • Bachelor of Science
Academic concentration
  • Biology
Honors level
  • Honors
Degree granting institution
  • University of North Carolina at Chapel Hill
Graduation year
  • 2018
Language
  • English

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