Auto-ubiquitination of Mdm2 Enhances Its Substrate Ubiquitin Ligase Activity

Ranaweera, Ruchira S.; Yang, Xiaolu

doi:10.1074/jbc.m113.454470

Cited by 56 publications

(59 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…and B). Moreover, MDM2 functioning as an E3 ubiquitin-protein ligase and proteasome activator [30], caused the degradation of p53 by protein polyubiquitination in miR501-5p-overexpressing KJ29 cells (Fig. 3C).…”

Section: Genementioning

confidence: 96%

Differential expression of microRNA501‐5p affects the aggressiveness of clear cell renal carcinoma

et al. 2014

View full text Add to dashboard Cite

show abstract

Section: Genementioning

confidence: 96%

Differential expression of microRNA501‐5p affects the aggressiveness of clear cell renal carcinoma

et al. 2014

View full text Add to dashboard Cite

show abstract

“…One such ligase is mouse double minute (Mdm2), which can direct its own ubiquitylation and subsequent proteasomal degradation (Ranaweera and Yang, 2013). In parallel, it has also been reported that the histone acetyl transferase p300-CBP-associated factor (PCAF, also known as KAT2B) ubiquitylates Mdm2, resulting in its proteasomal degradation (Linares et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Ubiquitin mediated regulation of the E3 ligase GP78 by Mahogunin in trans affects mitochondrial homeostasis

Mukherjee

Chakrabarti

2016

Journal of Cell Science

View full text Add to dashboard Cite

Cellular quality control provides an efficient surveillance system to regulate mitochondrial turnover. This study elucidates a new interaction between the cytosolic E3 ligase mahogunin RING finger 1 (MGRN1) and the endoplasmic reticulum (ER) ubiquitin E3 ligase GP78 (also known as AMFR). Loss of Mgrn1 function has been implicated in late-onset spongiform neurodegeneration and congenital heart defects, among several developmental defects. Here, we show that MGRN1 ubiquitylates GP78 in trans through noncanonical K11 linkages. This helps maintain constitutively low levels of GP78 in healthy cells, in turn downregulating mitophagy. GP78, however, does not regulate MGRN1. When mitochondria are stressed, cytosolic Ca 2+ increases. This leads to a reduced interaction between MGRN1 and GP78 and its compromised ubiquitylation. Chelating Ca 2+ restores association between the two ligases and the in trans ubiquitylation. Catalytic inactivation of MGRN1 results in elevated levels of GP78 and a consequential increase in the initiation of mitophagy. This is important because functional depletion of MGRN1 by the membrane-associated disease-causing prion protein Ctm PrP affects polyubiquitylation and degradation of GP78, also leading to an increase in mitophagy events. This suggests that MGRN1 participates in mitochondrial quality control and could contribute to neurodegeneration in a subset of Ctm PrP-mediated prion diseases.

show abstract

“…Yet despite intensive study, a role of DUBs in controlling MKRN1 stability has not been described. Our data suggest that autoubiquitination of MKRN1 could be an important control mechanism, as it is for MDM2, another p53 ubiquitin ligase 59 . Among the new substrates we identified, we found multiple transcription factors (n=7) and proteins involved in RNA metabolism (n=12).…”

Section: Discussionmentioning

confidence: 70%

Proteomics of broad deubiquitylase inhibition unmasks redundant enzyme function to reveal substrates

Rossio

Paulo

Chick

et al. 2019

Preprint

View full text Add to dashboard Cite

1Deubiquitylating enzymes (DUBs) counteract ubiquitylation to control the stability or activity of 2 their substrates. Identifying DUB substrates is challenging and genetic approaches can be 3 thwarted by redundant action of DUBs. Here, we circumvented redundancy by broadly inhibiting 4 DUBs in Xenopus egg extract and used quantitative mass spectrometry to identify over thirty 5 proteins that undergo proteasomal degradation, the majority of which have not been reported as 6 DUB substrates. These results were confirmed with recombinant human proteins, demonstrating 7 the conservation of their DUB-dependent stability. We used these substrates to profile the ability 8 of a panel of DUBs to rescue degradation. This approach revealed that USP7, uniquely among 9 the 14 DUBs tested, has a broad ability to rescue degradation. USP21, which is used widely to 10 nonspecifically deubiquitylate proteins in vitro, was unable to rescue degradation, highlighting 11 the importance of profiling enzyme activity in a physiological system. Together, we identify new 12 DUB substrates and present a system to characterize physiological DUB specificity, overcoming 13 the challenges posed by DUB redundancy. 14 2 Here, we first took an unbiased quantitative proteomic approach and discovered new 53 substrates protected from proteasomal degradation by DUBs, using the Xenopus egg extract 54 model system. By broadly inhibiting cysteine-protease DUBs, we circumvented the possible 55 effects of their redundancy on proteome stability. Because transcription and translation are not 56 active in this system, protein instability caused by DUB inhibition is not a consequence of 57 protein quality control ubiquitination activity. We recapitulated protein destabilization with 58 expression of recombinant human orthologs in extract, demonstrating that DUB-dependent 59 4 protein stability is evolutionarily conserved. Next, we took advantage of these newly identified 60 DUB substrates and tested the ability of a set of DUBs to rescue their degradation, uncovering a 61 broad ability of USP7 to rescue protein instability in extract. However, specific inhibition of 62 USP7 with a small molecule inhibitor was not sufficient to promote degradation of most of the 63 substrates we identified, suggesting that USP7 functions redundantly with other DUBs in this 64 system. Our work highlights the impact of DUB redundancy on proteome stability and reveals 65 the specificity and activity of DUBs whose function would otherwise be masked by redundancy. 66 67Results 68 UbVS treatment induces rapid depletion of available ubiquitin and labels a broad set of 69 cysteine-protease DUBs in Xenopus extract 70Our laboratory previously showed that the broad cysteine-protease DUB inhibitor UbVS 71 induces depletion of available ubiquitin in Xenopus extract 22 . In particular, UbVS-treatment 72 inhibited proteasome degradation of cyclin B, which could be efficiently rescued by addition of 73 50 µM exogenous ubiquitin 22 . We confirmed that 10 µM UbVS was sufficient to rapidly deplet...

show abstract

Auto-ubiquitination of Mdm2 Enhances Its Substrate Ubiquitin Ligase Activity

Cited by 56 publications

References 32 publications

Differential expression of microRNA501‐5p affects the aggressiveness of clear cell renal carcinoma

Differential expression of microRNA501‐5p affects the aggressiveness of clear cell renal carcinoma

Ubiquitin mediated regulation of the E3 ligase GP78 by Mahogunin in trans affects mitochondrial homeostasis

Proteomics of broad deubiquitylase inhibition unmasks redundant enzyme function to reveal substrates

Contact Info

Product

Resources

About