A post-ubiquitination role for MDM2 and hHR23A in the p53 degradation pathway

Brignone, Chrystelle; Bradley, Kathleen; Kisselev, Alexei F.; Grossman, Steven R.

doi:10.1038/sj.onc.1207540

Cited by 70 publications

(65 citation statements)

References 24 publications

(28 reference statements)

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“…Depletion of hHR23A and B with short interfering RNA (siRNA) results in more rapid degradation of p53 by the proteasome, whereas their overexpression induces the accumulation of ubiquitinated p53 (Glockzin et al, 2003;Brignone et al, 2004). These seemingly paradoxical effects of hHR23 proteins on p53 degradation are consistent with suggestions that the effects of Rad23/hHR23 on degradation are highly sensitive to stoichiometric variation (Raasi and Pickart, 2003;Verma et al, 2004).…”

Section: Introductionsupporting

confidence: 70%

“…These seemingly paradoxical effects of hHR23 proteins on p53 degradation are consistent with suggestions that the effects of Rad23/hHR23 on degradation are highly sensitive to stoichiometric variation (Raasi and Pickart, 2003;Verma et al, 2004). Additionally, hHR23A and B interact with mouse double minute 2 (MDM2), where MDM2 functions to antagonize the stabilizing function of hHR23 toward p53, directly promoting p53 recognition and degradation by the proteasome (Brignone et al, 2004). This model has been recently bolstered by the finding that MDM2, itself, contacts the 20S core particle of the proteasome (Sdek et al, 2005).…”

Section: Introductionsupporting

confidence: 54%

“…hHR23B-dependent accumulation of ubiquitinated p53 after DNA damage Given the requirement for hHR23B during physiologic p53 induction after DNA damage, along with its known protective effect on p53 degradation in unstressed cells (Brignone et al, 2004), we investigated the consequences of hHR23B depletion on DNA damage-induced changes in p53 ubiquitination. p53-Ub conjugates accumulate transiently in cells exposed to gamma irradiation, although the mechanism of accumulation and function of the conjugates has not been determined (Maki and Howley, 1997).…”

Section: Resultsmentioning

confidence: 99%

“…Physiologic hHR23B levels are required for normal p53 induction after DNA damage As hHR23 proteins play an important role in both DNA repair and the regulation of p53 stability (Sweder and Madura, 2002;Brignone et al, 2004), the effect of siRNA-mediated knockdown of hHR23B after treatment of cells with different DNA-damaging agents was investigated. U2OS cells were exposed to control or hHR23B siRNA and then mock-treated or treated with doxorubicin (Dox), UV, etoposide, gamma irradiation (IR) or mitomycin-C (MMC) for 3, 6 or 16 h. The doses of each agent (except for IR, which was not cytotoxic for U2OS) were those in the linear range for cytotoxicity (Supplementary Figure S1).…”

Section: Resultsmentioning

confidence: 99%

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hHR23B is required for genotoxic-specific activation of p53 and apoptosis

et al. 2006

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Rad23 proteins function in both DNA repair and protein stability regulation. As ubiquitinated forms of p53 are stabilized after DNA damage in concert with p53 functional activation, and human Rad23 proteins (hHR23A and B) regulate p53 stability in unstressed cells, the role of hHR23B in post-genotoxin regulation of p53 was investigated. Depletion of hHR23B by specific short interfering RNA before genotoxic exposure attenuated p53, p21 and bax induction, abrogated the accumulation of ubiquitinated p53 and suppressed apoptosis. Expression of ubiquitin derivatives with all lysines mutated except K48 or K63 demonstrated that K48-linked p53-ubiquitin conjugates were specifically induced after DNA damage. hHR23B, along with native and ubiquitinated p53, accumulated in chromatin after genotoxic exposure, and the accumulation of ubiquitinated p53 in chromatin was prevented by hHR23B depletion. Chromatin immunoprecipitation analysis demonstrated that hHR23B and p53 both localized to the p21 promoter shortly after DNA damage. hHR23B thus plays a critical role in the activation and function of p53 after specific genotoxic exposures.

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Section: Introductionsupporting

confidence: 70%

Section: Introductionsupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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hHR23B is required for genotoxic-specific activation of p53 and apoptosis

et al. 2006

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“…Interestingly, the UBA domain of the E3 ubiquitin ligase Cbl-b shows high homology with the USP13 UBA domain, can bind Siah1, inhibiting its degradation (20). Consistent with this finding, the UbL-UBA protein hHR23 reportedly binds to the E3 ligase mdm2 through its UBA domain and blocks p53 degradation (33).…”

Section: Discussionsupporting

confidence: 71%

USP13 Enzyme Regulates Siah2 Ligase Stability and Activity via Noncatalytic Ubiquitin-binding Domains

Scortegagna

Subtil

et al. 2011

Journal of Biological Chemistry

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The RING finger E3 ubiquitin ligase Siah2 is implicated in control of diverse cellular biological events, including MAPK signaling and hypoxia. Here we demonstrate that Siah2 is subject to regulation by the deubiquitinating enzyme USP13. Overexpression of USP13 increases Siah2 stability by attenuating its autodegradation. Consequently, the ability of Siah2 to target its substrates prolyl hydroxylase 3 and Spry2 (Sprouty2) for ubiquitin-mediated proteasomal degradation is attenuated. Conversely, inhibition of USP13 expression with corresponding shRNA decreases the stability of both Siah2 and its substrate Spry2. Thus, USP13 limits Siah2 autodegradation and its ubiquitin ligase activity against its target substrates. Strikingly, the effect of USP13 on Siah2 is not mediated by its isopeptidase activity: mutations in its ubiquitin-binding sequences positioned within the ubiquitin-specific processing protease and ubiquitin-binding domains, but not within putative catalytic sites, abolish USP13 binding to and effect on Siah2 autodegradation and targeted ubiquitination. Notably, USP13 expression is attenuated in melanoma cells maintained under hypoxia, thereby relieving Siah2 inhibition and increasing its activity under low oxygen levels. Significantly, on melanoma tissue microarray, high nuclear expression of USP13 coincided with high nuclear expression of Siah2. Overall, this study identifies a new layer of Siah2 regulation mediated by USP13 binding to ubiquitinated Siah2 protein with a concomitant inhibitory effect on its activity under normoxia.Siah proteins are RING finger E3 ubiquitin ligases implicated in the ubiquitination and proteasome-dependent degradation of substrate molecules, which also limit their own availability through self-ubiquitination and degradation (1-3). Siah was first identified in Drosophila melanogaster as seven in absentia (sina), which regulates formation of the R7 photoreceptor through control of tramtrack stability (4, 5). Three murine Siah genes (Siah1a, Siah1b, and Siah2) share significant homology with the two human (SIAH1 and SIAH2) orthologues (6, 7).Siah2 is an important regulator of pathways activated under stress and hypoxia. Among substrates reportedly regulated by Siah under these conditions are TRAF2, ␣-ketoglutarate dehydrogenase, Spry2 (Sprouty2), and two of the three prolyl hydroxylases (8 -10). Given the role of PHD proteins as oxygen sensors and regulators of HIF1␣, the master transcription factor responding to hypoxia, Siah is implicated in the control of hypoxia, particularly within the range of 2-6% oxygen at which PHD proteins retain sufficient activity (11,12). The role of Siah2 in tumor development has been extensively studied. Inhibition of Siah reportedly attenuates breast, pancreatic, lung, prostate, and melanoma tumors (13-16). Mechanistically, Siah2 contributes to tumor development and metastasis via its control of diverse substrates, as shown in a melanoma model (14).A search for novel Siah2 interacting factors led to identification of the isopeptidase USP13 ...

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Ubiquitin receptors play redundant roles in the proteasomal degradation of the p53 repressor MDM2

2022

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Much remains to be determined about the participation of ubiquitin receptors in proteasomal degradation and their potential as therapeutic targets. Suppression of the ubiquitin receptor S5A/PSMD4/hRpn10 alone stabilises p53/ TP53 but not the key p53 repressor MDM2. Here, we observed S5A and the ubiquitin receptors ADRM1/PSMD16/hRpn13 and RAD23A and B functionally overlap in MDM2 degradation. We provide further evidence that degradation of only a subset of ubiquitinated proteins is sensitive to S5A knockdown because ubiquitin receptor redundancy is commonplace. p53 can be upregulated by S5A modulation while degradation of substrates with redundant receptors is maintained. Our observations and analysis of Cancer Dependency Map (DepMap) screens show S5A depletion/loss substantially reduces cancer cell line viability. This and selective S5A dependency of proteasomal substrates make S5A a target of interest for cancer therapy.

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A post-ubiquitination role for MDM2 and hHR23A in the p53 degradation pathway

Cited by 70 publications

References 24 publications

hHR23B is required for genotoxic-specific activation of p53 and apoptosis

hHR23B is required for genotoxic-specific activation of p53 and apoptosis

USP13 Enzyme Regulates Siah2 Ligase Stability and Activity via Noncatalytic Ubiquitin-binding Domains

Ubiquitin receptors play redundant roles in the proteasomal degradation of the p53 repressor MDM2

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