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The link between met-enkephalin-induced down-regulation of APN activity and the release of superoxide anion

T Marotti1, T Balog, V Munić

  • 1Department of Molecular Medicine, Institute Rud-er Boksković, Bijenicka 54, 1000 Zagreb, Croatia.

Neuropeptides
|September 14, 2000
PubMed

Insights

Methionine-enkephalin (MENK) down-regulates aminopeptidase N (APN) activity in neutrophils, impacting superoxide anion production. This suggests APN, via CD13, plays a key role in MENK hydrolysis and opioid receptor binding.

Area of Science:

  • Immunology
  • Neuroscience
  • Biochemistry

Background:

  • Methionine-enkephalin (MENK) differentially affects superoxide anion (O(2)(-)) production in neutrophils.
  • This variability may stem from differing activities of enzymes that degrade MENK.

Purpose of the Study:

  • To investigate the association between MENK's effect on O(2)(-) release and two key neutrophil enzymes: aminopeptidase N (APN) and neutral endopeptidase (NEP).

Main Methods:

  • Assessed MENK's impact on APN and NEP activity in neutrophils.
  • Examined APN activity in intact neutrophils versus isolated membranes.
  • Investigated the effect of anti-CD13 monoclonal antibody (MoAb) WM15 on MENK's suppressive effect.

Main Results:

  • MENK down-regulated APN activity, but not NEP activity.
  • APN down-regulation occurred in intact neutrophils, suggesting internalization.
  • Inhibiting CD13 with MoAb WM15 abrogated MENK's suppressive effect on O(2)(-) release.

Conclusions:

  • Aminopeptidase N (APN) plays a dominant role in MENK hydrolysis in peripheral neutrophils, similar to the brain.
  • The findings support a link between membrane-associated CD13 and MENK's interaction with opioid receptors.

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