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NAD(P)H oxidase activity of Nox4 in chondrocytes is both inducible and involved in collagenase expression
Laurent Grange1, Minh Vu Chuong Nguyen, Bernard Lardy
1GREPI EA 2938 UJF, Lab Enzymology/DBPC, Universitary Hospital A. Michallon, Grenoble, France [corrected] LGrange@chu-grenoble.fr
Abstract:
Reactive oxygen species (ROS) are regulators of redox-sensitive cell signaling pathways. In osteoarthritis, human interleukin-1beta is implicated in cartilage destruction through an ROS-dependent matrix metalloproteinase production. To determine the molecular source of ROS production in the human IL-1beta (hIL-1beta)-sensitive chondrocyte immortalized cell line C-20/A4, transfected cells were constructed that overexpress NAD(P)H oxidases. First, RT-PCR analysis showed that the C-20/A4 cell line expressed Nox2, Nox4, p22( phox ), and p67( phox ), but not p47( phox ). It was found that ROS production by C-20/A4 chondrocytes does not depend on PMA and ionomycin activation. This indicates that Nox2 was not involved in the production of ROS. In C- 20/A4 cells that overexpress Nox4, hIL-1beta stimulated ROS production three times more than the normal production of C-20/A4 cells. Moreover, there was a fourfold increase in the production of collagenase (MMP-1) by chondrocytes that overexpress Nox4. Interestingly, MMP-1 production in cells that overexpress Nox2 was not sensitive to hIL-1beta. These data suggest that under hIL-1beta stimulation, C-20/A4 chondrocytes produce MMP-1 through a Nox4-mediated, ROS-dependent pathway.
Insights
Reactive oxygen species (ROS) regulate cell signaling. In osteoarthritis, human interleukin-1beta (hIL-1beta) drives cartilage destruction via ROS-dependent matrix metalloproteinase production, with Nox4 being the key enzyme.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Reactive oxygen species (ROS) are crucial signaling molecules involved in cellular processes.
- In osteoarthritis, human interleukin-1beta (hIL-1beta) contributes to cartilage degradation by stimulating ROS-dependent matrix metalloproteinase (MMP) production.
Purpose of the Study:
- To identify the specific NAD(P)H oxidase (Nox) enzyme responsible for ROS production in hIL-1beta-stimulated chondrocytes.
- To elucidate the role of ROS in mediating MMP-1 production by chondrocytes.
Main Methods:
- RT-PCR was used to analyze the expression of Nox isoforms and their subunits in the C-20/A4 chondrocyte cell line.
- Cells were transfected to overexpress Nox2 or Nox4.
- ROS production and MMP-1 levels were measured under various stimulation conditions.
Main Results:
- The C-20/A4 cell line expressed Nox2, Nox4, p22(phox), and p67(phox), but not p47(phox).
- hIL-1beta stimulation significantly increased ROS production and MMP-1 production in C-20/A4 cells overexpressing Nox4, but not Nox2.
- ROS production in C-20/A4 cells was independent of PMA and ionomycin activation, suggesting Nox2 was not involved.
Conclusions:
- Nox4 is the primary source of ROS production in hIL-1beta-stimulated C-20/A4 chondrocytes.
- hIL-1beta induces MMP-1 production through a Nox4-mediated, ROS-dependent pathway in these cells.
- These findings highlight the role of Nox4 in osteoarthritis pathogenesis.
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