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Prolyl hydroxylase domain protein 3 targets Pax2 for destruction

Bing Yan1, Shi Jiao, Hai-sheng Zhang

  • 1Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.

Biochemical and Biophysical Research Communications
|May 18, 2011
PubMed

Insights

Prolyl hydroxylase domain protein 3 (PHD3) directly degrades the transcription factor paired box 2 (Pax2). This PHD3-Pax2 interaction is disrupted in colorectal cancer, leading to increased Pax2 levels.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cancer Biology

Background:

  • Prolyl hydroxylase domain proteins (PHDs) regulate hypoxia-inducible factor alpha (HIFα) stability.
  • PHDs are increasingly recognized to target substrates beyond HIFα.
  • Aberrant paired box (Pax) 2 expression is implicated in various cancers, but regulatory mechanisms are unclear.

Purpose of the Study:

  • To investigate the role of PHD3 in regulating Pax2 expression.
  • To determine if PHD3 directly interacts with and degrades Pax2.
  • To explore the clinical relevance of the PHD3-Pax2 interaction in colorectal cancer.

Main Methods:

  • Co-immunoprecipitation assays to detect PHD3-Pax2 binding.
  • Western blotting to assess protein levels of Pax2 and PHD3.
  • Enzyme activity assays to evaluate PHD3 hydroxylase function.
  • Analysis of patient tumor samples for PHD3 and Pax2 expression.

Main Results:

  • PHD3 directly binds to Pax2 and mediates its proteasomal degradation.
  • Inhibition of PHD3 activity increases Pax2 protein levels, but not mRNA levels.
  • Pax2 protein is upregulated, while PHD3 protein is downregulated in colorectal cancer tissues.
  • Increased Pax2 levels correlate with decreased PHD3 levels in colorectal cancer.

Conclusions:

  • PHD3 acts as a negative regulator of Pax2 expression by targeting it for degradation.
  • The PHD3-Pax2 axis represents a novel regulatory pathway for Pax2.
  • Dysregulation of PHD3-mediated Pax2 degradation may contribute to colorectal cancer development.

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