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Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

Transcriptional regulation of mitotic checkpoint gene MAD1 by p53

Abel C S Chun1, Dong-Yan Jin

  • 1Department of Biochemistry, the University of Hong Kong, Hong Kong, China.

The Journal of Biological Chemistry
|July 24, 2003
PubMed

Insights

The tumor suppressor p53 protein inhibits Mitosis Arrest Deficiency 1 (MAD1) expression transcriptionally. This finding reveals a novel mechanism regulating the mitotic checkpoint and cancer progression.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • The tumor suppressor protein p53 is a key regulator of gene expression, involved in transcriptional activation and repression.
  • While p53's role in the mitotic checkpoint is known, the precise molecular mechanisms remain unclear.
  • Mitosis Arrest Deficiency 1 (MAD1) is a crucial human mitotic checkpoint protein.

Purpose of the Study:

  • To investigate the effect of p53 on the expression of the human mitotic checkpoint protein MAD1.
  • To elucidate the transcriptional regulation of MAD1 by p53.

Main Methods:

  • Overexpression of wild-type p53 in cultured human cells.
  • Treatment with anticancer agents (5-fluorouracil, cisplatin) and UV irradiation.
  • Analysis of MAD1 promoter activity, p53-responsive elements, histone deacetylase inhibition, and chromatin immunoprecipitation assays.

Main Results:

  • p53 overexpression and treatments inducing p53 activity reduced MAD1 expression.
  • p53 repressed MAD1 transcription via a novel 38-bp element on the MAD1 promoter, independent of known p53 binding sites.
  • Mutant p53 proteins retained the ability to repress MAD1; histone deacetylase inhibitors reversed this repression.

Conclusions:

  • p53 directly represses MAD1 expression at the transcriptional level, involving histone deacetylase 1 and mSin3a.
  • This provides a novel regulatory mechanism for the mitotic checkpoint.
  • Understanding this p53-MAD1 interaction offers insights into cancer progression and potential therapeutic strategies.

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