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Nitric oxide regulates prolidase activity by serine/threonine phosphorylation

Arkadiusz Surazynski1, Yongmin Liu, Wojciech Miltyk

  • 1Metabolism and Cancer Susceptibility Section, Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA.

Journal of Cellular Biochemistry
|September 17, 2005
PubMed

Insights

Nitric oxide (NO) enhances prolidase activity by increasing its phosphorylation through the PKG-cGMP pathway, independent of MAPK signaling. This reveals a novel link between NO signaling and matrix degradation regulation.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Signaling

Background:

  • Prolidase is a key enzyme in collagen metabolism and matrix remodeling.
  • Nitric oxide (NO) is a signaling molecule involved in processes like collagen synthesis and angiogenesis.
  • The interaction between NO and prolidase activity was previously unexplored.

Purpose of the Study:

  • To investigate the regulatory effect of nitric oxide (NO) on prolidase activity.
  • To elucidate the molecular mechanisms underlying NO-mediated prolidase activation.
  • To determine the signaling pathways involved in NO-dependent prolidase modulation.

Main Methods:

  • Utilized NO donors (SIN-1, DETA/NO) and inducible nitric oxide synthase (iNOS) expression to modulate NO levels.
  • Assessed prolidase activity and expression in response to NO.
  • Investigated protein phosphorylation, specifically serine/threonine phosphorylation on prolidase.
  • Examined the roles of cGMP and MAPK pathways using agonists, inhibitors, and specific pathway inhibitors (e.g., Rp-8-Br-pCPT-cGMP, ERK1/2 inhibitor).

Main Results:

  • Both exogenous and endogenous NO significantly increased prolidase activity in a time- and dose-dependent manner.
  • Increased prolidase activity was not associated with altered prolidase expression.
  • NO treatment led to increased serine/threonine phosphorylation of prolidase.
  • Activation of the PKG-cGMP pathway mimicked NO's effect on prolidase activity and phosphorylation.
  • Inhibition of cGMP signaling abolished NO-induced prolidase activation.
  • The MAPK pathway (ERK1/2) was not involved in NO-dependent prolidase activation.

Conclusions:

  • Nitric oxide stimulates prolidase activity via serine/threonine phosphorylation.
  • The PKG-cGMP pathway mediates NO-dependent prolidase activation.
  • MAPK signaling is not involved in this NO-mediated regulatory mechanism.
  • This study highlights a novel interaction between NO signaling and the regulation of matrix degradation.

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