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Nitric oxide-induced increase in p21(Sdi1/Cip1/Waf1) expression during the cell cycle in aortic adventitial

M Gu1, P Brecher

  • 1Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.

Arteriosclerosis, Thrombosis, and Vascular Biology
|January 15, 2000
PubMed

Insights

Nitric oxide (NO) inhibits fibroblast proliferation by increasing p21 expression. This occurs via a cyclic GMP-dependent pathway, involving p53 activation and enhanced DNA binding.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Nitric oxide (NO) is a signaling molecule with diverse physiological roles.
  • Cyclin-dependent kinase inhibitors, such as p21, regulate cell cycle progression.
  • The antiproliferative effects of NO are not fully understood at the molecular level.

Purpose of the Study:

  • To investigate if nitric oxide (NO) regulates p21(Sdi1/Cip1/Waf1) expression.
  • To determine if NO-induced p21 expression mediates the antiproliferative effects of NO in fibroblasts.
  • To elucidate the signaling pathway involved in NO-mediated p21 regulation.

Main Methods:

  • Fibroblast cell cultures were treated with NO donors (SNAP) and growth factors.
  • Cell proliferation was assessed by [3H]thymidine incorporation.
  • p21 mRNA and protein levels were analyzed by Northern and Western blotting.
  • p53 activation and DNA binding were studied using immunoprecipitation and electrophoretic mobility shift assays.
  • Cyclic GMP (cGMP) signaling was investigated using 8-bromo-cGMP and inhibitors of soluble guanylate cyclase and protein kinase G.

Main Results:

  • S-nitroso-N-acetyl-penicillamine (SNAP), an NO donor, significantly reduced fibroblast proliferation.
  • SNAP treatment rapidly induced p21 mRNA and protein expression.
  • SNAP enhanced p53 phosphorylation and DNA binding activity in a cell cycle-dependent manner.
  • The effects of SNAP were mimicked by 8-bromo-cGMP and blocked by inhibitors of soluble guanylate cyclase and protein kinase G.

Conclusions:

  • Nitric oxide (NO) acts as a regulator of the cell cycle in aortic adventitial fibroblasts.
  • NO induces p21 expression, contributing to its antiproliferative effect.
  • This regulation occurs through a cGMP-mediated transcriptional mechanism involving p53 activation.

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