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Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes
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Protein kinase C-mediated inhibition of cyclin A expression in human vascular endothelial cells

C Kosaka1, T Sasaguri, J Masuda

  • 1National Cardiovascular Center Research Institute, Osaka, Japan.

Biochemical and Biophysical Research Communications
|June 30, 1993
PubMed

Insights

Protein kinase C (PKC) negatively regulates human endothelial cell proliferation by inhibiting cyclin A gene transcription. This pathway arrests the cell cycle at G1/S, impacting DNA synthesis and cell doubling.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Vascular endothelial cell proliferation is crucial for tissue repair and angiogenesis.
  • The protein kinase C (PKC) pathway is implicated in regulating cell growth and differentiation.
  • Cyclin A is a key regulator of the G1/S phase transition in the cell cycle.

Purpose of the Study:

  • To investigate the mechanism by which PKC regulates endothelial cell proliferation.
  • To determine the role of cyclin A in PKC-mediated cell cycle arrest.
  • To elucidate how PKC affects cyclin A gene expression and transcription.

Main Methods:

  • Primary human vascular endothelial cells were cultured.
  • Cells were treated with phorbol 12-myristate, 13-acetate (PMA) to modulate PKC activity.
  • PKC depletion was achieved through long-term PMA exposure.
  • Cell proliferation, DNA synthesis, and cell cycle progression were assessed.
  • Cyclin A mRNA and protein levels were quantified using molecular biology techniques.
  • Gene transcription rates were measured to assess the impact on gene expression.

Main Results:

  • Phorbol 12-myristate, 13-acetate (PMA) inhibited DNA synthesis and cell population doubling in PKC-retaining cells.
  • PKC depletion rendered cells resistant to PMA-induced proliferation inhibition.
  • PMA treatment significantly reduced cyclin A mRNA and protein levels in a dose-dependent manner.
  • The reduction in cyclin A mRNA by PMA was attributed to the inhibition of gene transcription.
  • These effects were mimicked by 1,2-dioctanoylglycerol, confirming the involvement of PKC.

Conclusions:

  • The protein kinase C (PKC) pathway negatively regulates human endothelial cell proliferation.
  • PKC inhibits G1/S phase progression by suppressing cyclin A gene transcription.
  • This mechanism involves the downregulation of cyclin A, a key cell cycle regulator, leading to reduced endothelial cell proliferation.

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