EXCEED THE SPACE PROVIDED. Alterations of the tumor suppressor p53 are the most commonly identified mutations in human cancers. In responses to various stresses, p53 protein level and its activity are greatly induced. However, the mechanism how p53 responses to various stresses are activated largely remains unclear. Recent studies have suggested that various phosphorylation events of p53 might regulate p53 stability and activity. However, the physiological roles of these phosphorylation events of p53 in regulating p53 responses to DNA damage and other stresses remain to be determined. To address this issue, I propose to employ homologous recombination and LoxP-Cre-mediated deletion to introduce missense mutations (Ser/Thr to Ala mutation) at several potentially important p53 phosphorylation sites, including Serl 8 and Thr73/83, into the endogenous p53 in mice. Preliminary analysis of the p53 serl8A]a and p53 yhr73/83Alaprimary cells suggested that both phosphorylation events play important but distinct roles in regulating p53 stability and activity after DNA damage. The mechanism for the impaired p53 responses to DNA damage in these p53 knock-in mice and the effects of these mutations on the p53-dependent tumor suppression will be determined. In addition, employing the same approach, we will determine the potential functional redundancy between phosphorylation of p53 at Serl 8 and ser23 in regulating p53 responses to DNA damage. Phosphorylation of human p53 at Ser46 has been suggested an important role in regulating p53 apoptotic function. However, Ser46 of human p53 is not conserved in mouse p53. Therefore, a human p53 knock-in mouse model, in which exons 4-9 of mouse p53 gene was replaced with exons 4-9 of human p53 gene, will be used to address the physiological roles of this phosphorylation event. Two observations indicated the feasibility of this strategy. First, the humanized p53 is functionally equivalent to the endogenous mouse p53. Secondly, the DNA damage-induced signaling pathways leading to the phosphorylation of human p53 at Ser46 is conserved in mouse cells. Identification of the phosphorylation events that regulate p53 stability and activity will indicate the signaling pathways involved and thus reveal the mechanism how p53 responses are activated during various stresses or cellular senescence. PERFORMANCE SITE ========================================Section End===========================================

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA094254-03
Application #
6843126
Study Section
Pathology B Study Section (PTHB)
Program Officer
Pelroy, Richard
Project Start
2003-02-05
Project End
2008-01-30
Budget Start
2005-02-01
Budget End
2006-01-31
Support Year
3
Fiscal Year
2005
Total Cost
$275,880
Indirect Cost
Name
University of California San Diego
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Lu, X; Mazur, S J; Lin, T et al. (2014) The pluripotency factor nanog promotes breast cancer tumorigenesis and metastasis. Oncogene 33:2655-64
Zhang, Zhen-Ning; Chung, Sun-Ku; Xu, Zheng et al. (2014) Oct4 maintains the pluripotency of human embryonic stem cells by inactivating p53 through Sirt1-mediated deacetylation. Stem Cells 32:157-65
Kim, J; Nakasaki, M; Todorova, D et al. (2014) p53 Induces skin aging by depleting Blimp1+ sebaceous gland cells. Cell Death Dis 5:e1141
Lu, X; Liu, D P; Xu, Y (2013) The gain of function of p53 cancer mutant in promoting mammary tumorigenesis. Oncogene 32:2900-6
Lake, Blue B; Fink, J├╝rgen; Klemetsaune, Liv et al. (2012) Context-dependent enhancement of induced pluripotent stem cell reprogramming by silencing Puma. Stem Cells 30:888-97
Liu, Dongping; Xu, Yang (2011) p53, oxidative stress, and aging. Antioxid Redox Signal 15:1669-78
Liu, Dongping; Ou, Linda; Clemenson Jr, Gregory D et al. (2010) Puma is required for p53-induced depletion of adult stem cells. Nat Cell Biol 12:993-8
Liu, D P; Song, H; Xu, Y (2010) A common gain of function of p53 cancer mutants in inducing genetic instability. Oncogene 29:949-56
Gaidarenko, O; Xu, Y (2009) Transcription activity is required for p53-dependent tumor suppression. Oncogene 28:4397-401
Jenkins, Lisa M Miller; Mazur, Sharlyn J; Rossi, Matteo et al. (2008) Quantitative proteomics analysis of the effects of ionizing radiation in wild type and p53 K317R knock-in mouse thymocytes. Mol Cell Proteomics 7:716-27

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