MDM2 mediates p73 ubiquitination: a new molecular mechanism for suppression of p73 function
نویسندگان
چکیده
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.
منابع مشابه
Pirh2, a ubiquitin E3 ligase, inhibits p73 transcriptional activity by promoting its ubiquitination.
p73, a homolog of the tumor suppressor p53, transactivates many p53 target genes, leading to apoptosis or cell-cycle arrest. p73 has recently been reported to play an important role in tumor suppression in a mouse model. Here, we show that Pirh2 physically interacted with p73 and downregulated p73 function through its E3 ligase activity. Pirh2 promoted p73 ubiquitination in vivo and in vitro. I...
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p73, a homolog of the tumor suppressor p53, transactivates many p53 target genes, leading to apoptosis or cellcycle arrest. p73 has recently been reported to play an important role in tumor suppression in amousemodel. Here, we show that Pirh2 physically interacted with p73 and downregulated p73 function through its E3 ligase activity. Pirh2 promoted p73 ubiquitination in vivo and in vitro. Intr...
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