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Published on: August 4, 2019

Regulation of p53-MDMX interaction by casein kinase 1 alpha

Lihong Chen1, Changgong Li, Yu Pan

  • 1H. Lee Moffitt Cancer Center, MRC3057A, 12902 Magnolia Drive, Tampa, FL 33612, USA.

Molecular and Cellular Biology
|July 19, 2005
PubMed

Insights

Casein kinase 1 alpha (CK1alpha) binds and phosphorylates MDMX, enhancing its inhibition of p53. Inhibiting CK1alpha activates p53, crucial for cellular stress responses.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Biochemistry

Background:

  • MDMX is a homolog of MDM2, crucial for regulating p53 in development.
  • MDMX degradation is primarily controlled by MDM2-mediated ubiquitination.
  • Other regulatory mechanisms for MDMX remain largely unexplored.

Purpose of the Study:

  • To investigate novel regulatory mechanisms of MDMX.
  • To determine the role of casein kinase 1 alpha (CK1alpha) in MDMX regulation.
  • To elucidate how CK1alpha influences the interaction between MDMX and p53.

Main Methods:

  • Co-immunoprecipitation assays to detect protein binding.
  • In vitro kinase assays to confirm phosphorylation.
  • Small interfering RNA (siRNA) to inhibit CK1alpha expression.
  • Analysis of p53 transcriptional activity and apoptosis induction.

Main Results:

  • MDMX directly binds to CK1alpha and is phosphorylated by it on serine 289.
  • CK1alpha expression enhances MDMX binding to p53, inhibiting p53's transcriptional activity.
  • Inhibition of CK1alpha by siRNA activates p53, particularly after ionizing irradiation.
  • CK1alpha inhibition cooperates with DNA damage to promote apoptosis.

Conclusions:

  • CK1alpha is a novel, functionally significant binding partner of MDMX.
  • CK1alpha regulates MDMX-p53 interactions and modulates p53 activity under normal and stress conditions.
  • Targeting CK1alpha represents a potential strategy for modulating p53 activity in cancer therapy.

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