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NADPH oxidase 4 mediates upregulation of type 4 phosphodiesterases in human endothelial cells

Saima Muzaffar1, Jamie Y Jeremy, Gianni D Angelini

  • 1Bristol Heart Institute, University of Bristol, Bristol, UK.

Journal of Cellular Physiology
|July 7, 2011
PubMed

Insights

NADPH oxidase (Nox) upregulation increases type 4 phosphodiesterases (PDE4), reducing cyclic AMP (cAMP) and promoting endothelial cell replication and angiogenesis. This Nox4-PDE4 pathway impacts vascular dysfunction.

Area of Science:

  • Endothelial Cell Biology
  • Vascular Biology
  • Biochemistry

Background:

  • Prostacyclin (PGI2) signaling, mediated by cyclic AMP (cAMP), is crucial for endothelial function.
  • Type 4 phosphodiesterases (PDE4) hydrolyze cAMP, reducing PGI2's protective effects.
  • NADPH oxidase (Nox)-derived superoxide is linked to impaired PGI2 bioactivity.

Purpose of the Study:

  • To investigate the relationship between Nox and PDE4 expression in human umbilical vein endothelial cells (HUVECs).
  • To determine the role of Nox4 and Nox5 in regulating PDE4 expression and endothelial cell functions.

Main Methods:

  • HUVECs were treated with U46619, 8-isoprostane F2α, or TNFα, with or without iloprost.
  • Expression of PDE4 isoforms (A, B, C, D) and Nox4/Nox5 was assessed via Western blotting and qPCR.
  • mRNA silencing of Nox4 and Nox5 was employed to study their functional roles.
  • Effects on cell replication and angiogenesis (tubule formation) were evaluated.

Main Results:

  • U46619, 8IP, and TNFα increased Nox4, Nox5, and all PDE4 isoform expression.
  • These stimuli also enhanced cell replication and tubule formation.
  • mRNA silencing of Nox4, but not Nox5, inhibited these increases.
  • Iloprost and rolipram (a PDE4 inhibitor) also reversed the effects.

Conclusions:

  • Upregulation of Nox4 leads to increased expression of PDE4A, B, and D, augmenting cAMP hydrolysis.
  • This mechanism enhances endothelial cell replication and angiogenesis, contributing to vasculopathies.
  • The PGI2-cAMP signaling axis, modulated by Nox4 and PDE4, is central to endothelial dysfunction in vascular diseases.

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