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Purification of Ubiquitinated p53 Proteins from Mammalian Cells
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The p53-Mdm2 feedback loop protects against DNA damage by inhibiting p53 activity but is dispensable for p53

Vinod Pant1, Shunbin Xiong, James G Jackson

  • 1Department of Genetics.

Genes & Development
|August 27, 2013
PubMed

Insights

The p53-Mdm2 feedback loop is crucial for regulating hematopoietic stem cell function after DNA damage. Disrupting this loop can sensitize stem cells, offering potential therapeutic strategies for blood cancers.

Area of Science:

  • Molecular Biology
  • Cancer Biology
  • Genetics

Background:

  • The p53-Mdm2 feedback loop is thought to regulate p53 activity during cellular stress.
  • In vivo validation of this feedback loop's necessity has been lacking.

Purpose of the Study:

  • To investigate the in vivo role of the p53-Mdm2 feedback loop in regulating p53 activity and cellular responses to DNA damage.
  • To assess the physiological consequences of disrupting the p53-Mdm2 feedback loop.

Main Methods:

  • Generation of Mdm2(P2/P2) mice with mutated p53 response elements in the Mdm2 P2 promoter.
  • Analysis of p53 degradation kinetics and DNA damage response in various tissues, including hematopoietic stem cells (HSCs).

Main Results:

  • Mdm2(P2/P2) mice were viable and exhibited normal aging, indicating basal Mdm2 levels suffice for p53 regulation in most tissues.
  • Despite normal basal conditions, DNA damage induced an elevated p53 response in Mdm2(P2/P2) mice.
  • Enhanced p53-dependent apoptosis led to HSC sensitization, myeloablation, and lethality.

Conclusions:

  • The p53-Mdm2 feedback loop is essential for sustaining HSC function and managing p53 activity following DNA damage.
  • Targeting the p53-Mdm2 interaction may offer a therapeutic approach for hematological malignancies by affecting stem cells.
Keywords:
autoregulatory loopbone marrowhematopoietic stem cellsionizing radiationp53 stability

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