Pirh2, a Ubiquitin E3 Ligase, Inhibits p73 Transcriptional Activity by Promoting Its Ubiquitination

Wu, Hong; Zeinab, Rami Abou; Flores, Elsa R.; Leng, Roger

doi:10.1158/1541-7786.mcr-11-0157

Cited by 39 publications

(31 citation statements)

References 43 publications

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“…3 In addition to p53, other ubiquitylation substrates have been also reported for PIRH2, including c-Myc, 4 p27kip1, 5 e-COP, 6 the signal recognition particle receptor b subunit, 7 the DNA polymerase eta 8 and p73. 9,10 The serine threonine kinase CHK2 (checkpoint kinase 2) is a checkpoint effector important for the signaling of DNA double-strand breaks and the activation of cell-cycle checkpoints. 11 In response to DNA damage, ataxia telangiectasia mutated (ATM) phosphorylates CHK2 on its threonine 68 (T68) and allows it to interact with the FHA domain of another CHK2.…”

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confidence: 99%

The E3 ligase PIRH2 polyubiquitylates CHK2 and regulates its turnover

et al. 2013

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The serine threonine kinase checkpoint kinase 2 (CHK2) is a DNA damage checkpoint protein important for the ATM-p53 signaling pathway. In addition to its phosphorylation, CHK2 is also ubiquitylated, and both post-translational modifications are important for its function. However, although the mechanisms that regulate CHK2 phosphorylation are well established, those that control its ubiquitylation are not fully understood. In this study, we demonstrate that the ubiquitin E3 ligase PIRH2 (p53-induced protein with a RING (Really Interesting New Gene)-H2 domain) interacts with CHK2 and mediates its polyubiquitylation and proteasomal degradation. We show that the deubiquitylating enzyme USP28 forms a complex with PIRH2 and CHK2 and antagonizes PIRH2-mediated polyubiquitylation and proteasomal degradation of CHK2. We also provide evidence that CHK2 ubiquitylation by PIRH2 is dependent on its phosphorylation status. Cells deficient in Pirh2 displayed accumulation of Chk2 and enhanced hyperactivation of G1/S and G2/M cell-cycle checkpoints. This hyperactivation was, however, no longer observed in Pirh2 PIRH2 (p53-induced protein with a RING (Really Interesting New Gene)-H2 domain), also known as RCHY1, encodes for an ubiquitin (Ub) ligase that is transcriptionally regulated by p53.1 PIRH2 interacts with the active tetrameric form of p53, mediates its ubiquitylation and regulates its turnover via Ubproteasome mechanisms.1,2 PIRH2 exerts its ubiquitylation function in cooperation with the E2 Ub-conjugating enzyme UbcH5b.1 A recent study indicated that PIRH2 negative regulation of p53 is enhanced in the presence of the ubiquitylation factor E4B.3 In addition to p53, other ubiquitylation substrates have been also reported for PIRH2, including c-Myc, 4 p27kip1, 5 e-COP, 6 the signal recognition particle receptor b subunit, 7 the DNA polymerase eta 8 and p73. 9,10The serine threonine kinase CHK2 (checkpoint kinase 2) is a checkpoint effector important for the signaling of DNA double-strand breaks and the activation of cell-cycle checkpoints.11 In response to DNA damage, ataxia telangiectasia mutated (ATM) phosphorylates CHK2 on its threonine 68 (T68) and allows it to interact with the FHA domain of another CHK2.12-14 This dimerization of CHK2 leads to its autophosphorylation on T383 and T387 and promotes its full activation.15-17 CHK2 phosphorylates p53 on Serine 20 (S23 for mouse) in response to DNA damage and has also other phosphorylation substrates, including PML, E2F1, CDC25C and BRCA1, highlighting its importance in processes such as DNA repair, cell-cycle arrest, apoptosis and senescence.18 CHK2 is also involved in DNA repair via the phosphorylation of Forkhead Box M1. 19 In addition, in collaboration with BRCA1, and independently of p53, CHK2 is required for the normal progression of mitosis and chromosomal stability. 20,21Although Chk2 is phosphorylated and activated primarily by the kinase ATM, it is also ubiquitylated; however, the mechanism of this ubiquitylation remains poorly understood.11 In this study, we rep...

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The E3 ligase PIRH2 polyubiquitylates CHK2 and regulates its turnover

et al. 2013

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“…27,[44][45][46] A more recent report suggested that the RING E3 ubiquitin ligase Pirh2 bound to the DBD and C-terminus (aa 123-313) of p73. 55 This was not a region that Pirh2 reportedly bound to on p53 (Figure 1), suggesting that p28 did not directly block the binding of Pirh2 on p73 and alter its ubiquitination. 4,54 p73 turnover was also reportedly regulated by Pirh2, but not by COP1 or Mdm2.…”

Section: Discussionmentioning

confidence: 92%

“…This suggests that the p28 binding motif on p53 and p63 is not analogous to that 54 TAp73 is also ubiquitinated by Pirh2 reportedly within the DBD (aa 123-313), suggesting that p28 may also indirectly increase Pirh2 ubiquitination of p73 by increasing the level of p53. 8,20,55 p28 alters the level of p63 and p73 p28 alters the ubiquitination of p63 and p73…”

Section: 8mentioning

confidence: 99%

A nanotechnological, molecular-modeling, and immunological approach to study the interaction of the anti-tumorigenic peptide p28 with the p53 family of proteins

Coppari¹,

Yamada²,

Bizzarri³

et al. 2014

IJN

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p28 is an anionic, amphipathic, cell-penetrating peptide derived from the cupredoxin azurin that binds to the DNA-binding domain (DBD) of the tumor suppressor protein, p53, and induces a post-translational increase in the level of wild type and mutated p53 in a wide variety of human cancer cells. As p63 and p73, additional members of the p53 superfamily of proteins, also appear to be involved in the cellular response to cancer therapy and are reportedly required for p53-induced apoptosis, we asked whether p28 also binds to p63 and p73. Atomic force spectroscopy demonstrates that p28 forms a stable, high-affinity complex with full-length p63, the DBD of p63, and full-length p73. Exposure to p28 decreased the level of TAp63α and ΔNp63α, the truncated form of p63, in p53 wild type and mutated human breast cancer cells, respectively. p28 increased the level of TAp73α, but not ΔNp73α, in the same breast cancer cell lines. In contrast, p28 increased the level of the TA and ΔN isoforms of p63 in p53 wild type, but not in p53 mutated melanoma cells, while decreasing TA p73α in p53 wild type and mutated human melanoma cells. All changes were mirrored by an associated change in the expression of the HECT E3 ligases Itch/AIP4, AIP5, and the RING E3 ligase Pirh2, but not in the receptor for activated C kinase or the RING E3 ligases Mdm2 and Cop1. Collectively, the data suggest that molecules such as p28 bind with high affinity to the DBD of p63 and p73 and alter their expression independent of the Mdm2 and Cop1 pathways.

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“…p63 and p73 share 60% similarity with the p53 DNA binding domain, allowing them to transactivate some of the same target genes. Like p53, p73 proteasomal turnover is regulated by the E3 ligase PIRH2 (Jung et al, 2011; Wu et al, 2011c) and also by the E4 ligase UFD2a (Hosoda et al, 2005). Furthermore, p63 and p73 protein stability are directly regulated by the ubiquitin ligase ITCH (Rossi et al, 2005, 2006).…”

Section: P53—signal Transducer From Dna Damage To Cellular Actionsmentioning

confidence: 99%

Regulation of the DNA damage response by ubiquitin conjugation

et al. 2015

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In response to DNA damage, cells activate a highly conserved and complex kinase-based signaling network, commonly referred to as the DNA damage response (DDR), to safeguard genomic integrity. The DDR consists of a set of tightly regulated events, including detection of DNA damage, accumulation of DNA repair factors at the site of damage, and finally physical repair of the lesion. Upon overwhelming damage the DDR provokes detrimental cellular actions by involving the apoptotic machinery and inducing a coordinated demise of the damaged cells (DNA damage-induced apoptosis, DDIA). These diverse actions involve transcriptional activation of several genes that govern the DDR. Moreover, recent observations highlighted the role of ubiquitylation in orchestrating the DDR, providing a dynamic cellular regulatory circuit helping to guarantee genomic stability and cellular homeostasis (Popovic et al., 2014). One of the hallmarks of human cancer is genomic instability (Hanahan and Weinberg, 2011). Not surprisingly, deregulation of the DDR can lead to human diseases, including cancer, and can induce resistance to genotoxic anti-cancer therapy (Lord and Ashworth, 2012). Here, we summarize the role of ubiquitin-signaling in the DDR with special emphasis on its role in cancer and highlight the therapeutic value of the ubiquitin-conjugation machinery as a target in anti-cancer treatment strategy.

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Pirh2, a Ubiquitin E3 Ligase, Inhibits p73 Transcriptional Activity by Promoting Its Ubiquitination

Cited by 39 publications

References 43 publications

The E3 ligase PIRH2 polyubiquitylates CHK2 and regulates its turnover

The E3 ligase PIRH2 polyubiquitylates CHK2 and regulates its turnover

A nanotechnological, molecular-modeling, and immunological approach to study the interaction of the anti-tumorigenic peptide p28 with the p53 family of proteins

Regulation of the DNA damage response by ubiquitin conjugation

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