Research Papers:

MDM2 mediates p73 ubiquitination: a new molecular mechanism for suppression of p73 function

Hong Wu _ and Roger P. Leng

PDF  |  HTML  |  Supplementary Files  |  How to cite

Oncotarget. 2015; 6:21479-21492. https://doi.org/10.18632/oncotarget.4086

Metrics: PDF 1946 views  |   HTML 2178 views  |   ?  


Hong Wu1, Roger P. Leng1

1Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada

Correspondence to:

Hong Wu, e-mail: [email protected]

Roger P. Leng, e-mail: [email protected]

Keywords: ubiquitin E3 ligase, ubiquitination, tumor suppressor, oncogene, protein degradation

Received: March 11, 2015     Accepted: May 14, 2015     Published: May 26, 2015


The protein p73, a homologue of the tumor suppressor protein p53, is capable of inducing apoptosis and cell cycle arrest. MDM2 is transcriptionally activated by p73 and represses the functions of p73, including p73-dependent transactivation and growth suppression. However, the molecular mechanism of this repression is unknown. In this study, we show that MDM2 mediates p73 ubiquitination. MDM2 mainly utilizes K11, K29 and K63-linked chains to mediate p73 ubiquitination in vivo and in vitro. However, MDM2 is unable to promote p73 degradation in most tested cell lines. Surprisingly, we observe that overexpression of Mdm2 promotes p73 degradation mainly through Itch in Mdm2-null MEFs. We further find that Itch interacts with the transfected Mdm2 in Mdm2-null cells. Moreover, our findings reveal that the E3 ligase activity of MDM2 is required to repress p73-dependent apoptosis and cell cycle arrest but not p73-dependent transcriptional activity. Furthermore, the data suggest a link between p73 ubiquitination/MDM2 E3 ligase activity and p73 biological functions.

Creative Commons License All site content, except where otherwise noted, is licensed under a Creative Commons Attribution 4.0 License.
PII: 4086