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Dmp1 physically interacts with p53 and positively regulates p53's stability, nuclear localization, and function.

ABSTRACT: The transcription factor Dmp1 is a Ras/HER2-activated haplo-insufficient tumor suppressor that activates the Arf/p53 pathway of cell-cycle arrest. Recent evidence suggests that Dmp1 may activate p53 independently of Arf in certain cell types. Here, we report findings supporting this concept with the definition of an Arf-independent function for Dmp1 in tumor suppression. We found that Dmp1 and p53 can interact directly in mammalian cells via the carboxyl-terminus of p53 and the DNA-binding domain of Dmp1. Expression of Dmp1 antagonized ubiquitination of p53 by Mdm2 and promoted nuclear localization of p53. Dmp1-p53 binding significantly increased the level of p53, independent of the DNA-binding activity of Dmp1. Mechanistically, p53 target genes were activated synergistically by the coexpression of Dmp1 and p53 in p53(-/-);Arf(-/-) cells, and genotoxic responses of these genes were hampered more dramatically in Dmp1(-/-) and p53(-/-) cells than in Arf(-/-) cells. Together, our findings identify a robust new mechanism of p53 activation mediated by direct physical interaction between Dmp1 and p53.

SUBMITTER: Frazier DP

PROVIDER: S-EPMC3319807 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Dmp1 physically interacts with p53 and positively regulates p53's stability, nuclear localization, and function.

Frazier Donna P DP Kendig Robert D RD Kai Fumitake F Maglic Dejan D Sugiyama Takayuki T Morgan Rachel L RL Fry Elizabeth A EA Lagedrost Sarah J SJ Sui Guangchao G Inoue Kazushi K

Cancer research 20120213 7

The transcription factor Dmp1 is a Ras/HER2-activated haplo-insufficient tumor suppressor that activates the Arf/p53 pathway of cell-cycle arrest. Recent evidence suggests that Dmp1 may activate p53 independently of Arf in certain cell types. Here, we report findings supporting this concept with the definition of an Arf-independent function for Dmp1 in tumor suppression. We found that Dmp1 and p53 can interact directly in mammalian cells via the carboxyl-terminus of p53 and the DNA-binding domai ...[more]

PMID: 22331460

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Project description:Enterovirus 71 (EV71) recruits various cellular factors to assist in the replication and translation of its genome. Identification of the host factors involved in the EV71 life cycle not only will enable a better understanding of the infection mechanism but also has the potential to be of use in the development of antiviral therapeutics. In this study, we demonstrated that the cellular factor 68-kDa Src-associated protein in mitosis (Sam68) acts as an internal ribosome entry site (IRES) trans-acting factor (ITAF) that binds specifically to the EV71 5' untranslated region (5'UTR). Interaction sites in both the viral IRES (stem-loops IV and V) and the heterogeneous nuclear ribonucleoprotein K homology (KH) domain of Sam68 protein were further mapped using an electrophoretic mobility shift assay (EMSA) and biotin RNA pulldown assay. More importantly, dual-luciferase (firefly) reporter analysis suggested that overexpression of Sam68 positively regulated IRES-dependent translation of virus proteins. In contrast, both IRES activity and viral protein translation significantly decreased in Sam68 knockdown cells compared with the negative-control cells treated with short hairpin RNA (shRNA). However, downregulation of Sam68 did not have a significant inhibitory effect on the accumulation of the EV71 genome. Moreover, Sam68 was redistributed from the nucleus to the cytoplasm and interacts with cellular factors, such as poly(rC)-binding protein 2 (PCBP2) and poly(A)-binding protein (PABP), during EV71 infection. The cytoplasmic relocalization of Sam68 in EV71-infected cells may be involved in the enhancement of EV71 IRES-mediated translation. Since Sam68 is known to be a RNA-binding protein, these results provide direct evidence that Sam68 is a novel ITAF that interacts with EV71 IRES and positively regulates viral protein translation.The nuclear protein Sam68 is found as an additional new host factor that interacts with the EV71 IRES during infection and could potentially enhance the translation of virus protein. To our knowledge, this is the first report that describes Sam68 actively participating in the life cycle of EV71 at a molecular level. These studies will not only improve our understanding of the replication of EV71 but also have the potential for aiding in developing a therapeutic strategy against EV71 infection.

Dataset Information

Dmp1 physically interacts with p53 and positively regulates p53's stability, nuclear localization, and function.

Publications

Dmp1 physically interacts with p53 and positively regulates p53's stability, nuclear localization, and function.

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