Research Papers: Pathology:
Mutant p53 accumulates in cycling and proliferating cells in the normal tissues of p53 R172H mutant mice
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Amanda M. Goh1,*, Yuezhen Xue1,*, Marc Leushacke2, Ling Li1, Julin S. Wong1, Poh Cheang Chiam1, Siti Aishah Binte Rahmat1, Michael B. Mann3,5, Karen M. Mann3,5, Nick Barker2, Guillermina Lozano4, Tamara Terzian4 and David P. Lane1
1 p53 Laboratory, A*STAR, Singapore
2 Institute of Medical Biology, A*STAR, Singapore
3 Institute of Molecular and Cell Biology, A*STAR, Singapore
4 Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
5 Cancer Research Program, Houston Methodist Research Institute, Houston, TX, USA
* These authors have contributed equally to this work
David P. Lane, email:
Keywords: mutant p53, p53 R172H mouse model, small intestine, proliferation, Mdm2 inhibitor, Pathology
Received: June 25, 2015 Accepted: July 05, 2015 Published: July 22, 2015
The tumour suppressor p53 is regulated primarily at the protein level. In normal tissues its levels are maintained at a very low level by the action of specific E3 ligases and the ubiquitin proteosome pathway. The mutant p53 protein contributes to transformation, metastasis and drug resistance. High levels of mutant p53 can be found in tumours and the accumulation of mutant p53 has previously been reported in pathologically normal cells in human skin. We show for the first time that similarly elevated levels of mutant p53 can be detected in apparently normal cells in a mutant p53 knock-in mouse model. In fact, in the small intestine, mutant p53 spontaneously accumulates in a manner dependent on gene dosage and cell type. Mutant p53 protein is regulated similarly to wild type p53, which can accumulate rapidly after induction by ionising radiation or Mdm2 inhibitors, however, the clearance of mutant p53 protein is much slower than wild type p53. The accumulation of the protein in the murine small intestine is limited to the cycling, crypt base columnar cells and proliferative zone and is lost as the cells differentiate and exit the cell cycle. Loss of Mdm2 results in even higher levels of p53 expression but p53 is still restricted to proliferating cells in the small intestine. Therefore, the small intestine of these p53 mutant mice is an experimental system in which we can dissect the molecular pathways leading to p53 accumulation, which has important implications for cancer prevention and therapy.
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