Nuclear-Cytoplasmic Shuttling of the Oncogenic Mouse UNP/USP4 Deubiquitylating Enzyme

Many membrane proteins incur a folding problem during biosynthesis; only a fraction thereof is exported from the endoplasmic reticulum (ER), because quality control is stringent. This is also true for G protein-coupled receptors. Here, we identify the deubiquitinating enzyme Usp4 as an interaction partner of the A 2a adenosine receptor, a G s -coupled receptor. Usp4 binds to the carboxyl terminus of the A 2A receptor and allows for its accumulation as deubiquinated protein. This relaxes ER quality control and enhances cell surface expression of functionally active receptor. The effect of Usp4 on the A 2A receptor was specific because 1) it was not seen in C-terminally truncated versions of the receptor; 2) it was not mimicked by Usp14, another member of the ubiquitin-specific protease family; and 3) it was not seen with the metabotropic glutamate receptor-5, another G protein-coupled receptor with a high propensity for intracellular retention. These observations show that deubiquinating enzymes can regulate quality control in the ER.

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“…The ratio of nuclear-to-cytosolic distribution is dependent on the cell type (Soboleva et al, 2005). The data shown in Fig.…”

Section: Resultsmentioning

confidence: 80%

The Ubiquitin-Specific Protease Usp4 Regulates the Cell Surface Level of the A2a Receptor

Milojević

Reiterer²,

Stefan³

et al. 2006

Molecular Pharmacology

117

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“…hUSP15 was observed both in the cytoplasm of NIH3T3 and HeLa cells as well as in HeLa nucleoli (33). Only recently, hUSP15 has been found to co-purify with the human COP9 signalosome (CSN) complex (11) and suggested to be the human homolog of the Saccharomyces pombe Ubp12 protein that regulates the activity of CSN-associated cullin-RING ubiquitin ligases (34,35).…”

Section: Discussionmentioning

confidence: 99%

Solution Structure of the Human Ubiquitin-specific Protease 15 DUSP Domain

Jong¹,

Ab²,

Diercks

et al. 2006

Journal of Biological Chemistry

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Ubiquitin-specific proteases (USPs) can remove covalently attached ubiquitin moieties from target proteins and regulate both the stability and ubiquitin-signaling state of their substrates. All USPs contain a conserved catalytic domain surrounded by one or more subdomains, some of which contribute to target recognition. One such specific subdomain, the DUSP domain (domain present in ubiquitin-specific proteases), is present in at least seven different human USPs that regulate the stability of or interact with the hypoxia-inducible transcription factor HIF1-␣, the Von HippelLindau protein (pVHL), cullin E3 ligases, and BRCA2. We describe the NMR solution structure of the DUSP domain of human USP15, recently implicated in COP9 (constitutive photomorphogenic gene 9) -signalosome regulation. Its tripod-like structure consists of a 3-fold ␣-helical bundle supporting a triple-stranded anti-parallel ␤-sheet. The DUSP domain displays a novel fold, an ␣/␤ tripod (AB3). DUSP domain surface properties and previously described work suggest a potential role in protein/protein interaction or substrate recognition.There are at least 67 human deubiquitinating enzymes, subdivided in ubiquitin-specific proteases (USPs) 4 and ubiquitin carboxyl-terminal hydrolases. By removing covalently attached ubiquitin moieties from target proteins, USPs counteract the activity of a relatively small number of E2 enzymes and hundreds of E3 enzymes responsible for specific protein ubiquitination. The subclass of ubiquitin carboxyl-terminal hydrolase enzymes cleaves ubiquitin from small peptides. Deubiquitination serves a number of roles: it protects Lys 48 -linked polyubiquitinated proteins from targeting to the proteasome and subsequent degradation, but can also control the signaling state characterized by monoubiquitination or Lys 63 -linked polyubiquitination (1). Human USP7 was shown to stabilize p53 and, as a consequence, affect cell viability and apoptosis. Initial observations suggested that USP7 stabilizes p53 by direct binding and deubiquitination of p53 (2, 3). Subsequently, USP7 was also demonstrated to deubiquitinate the murine double minute 2 homolog protein, the E3 ubiquitin ligase that targets p53 for proteasomal degradation. The total absence of USP7 destabilized murine double minute 2 homolog, causing an indirect stimulation of p53 protein stability (4, 5). The balance in deubiquitination of these two targets might determine the net outcome of both opposing actions. If the flexibility in target recognition by USP7 is exemplary for the whole USP protein family, unraveling USP-regulated ubiquitin signaling and USP target specificity will prove a challenging task.A first structural view on the action of USPs was provided by the crystal structure of the USP7 catalytic domain in complex with a covalently attached ubiquitin aldehyde that specifically inhibits USP enzymes (3). The ubiquitin moiety is recognized by an extended protein surface, and its carboxyl-terminal region contacts a narrow groove containing the conserved catalytic t...

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“…Otherwise the three isoforms that retain the catalytic domain are identical. They also retain predicted nuclear export signals (NES) (Soboleva et al, 2005) and, by homology with rat, a functional nuclear localisation signal (NLS) (Park et al, 2000).…”

Section: Descriptionmentioning

confidence: 99%

“…Rat UBP109 localises to both the cytoplasm and the nuclear compartment, with the latter dependent on a C-terminal NLS (Park et al, 2000) that is conserved across species. Using an Usp15/USP15-specific polyclonal antibody, Soboleva et al demonstrated that in HeLa (human cervical cancer cells) endogenous USP15 localised to the cytoplasm and nucleolus, but was largely excluded from the nucleoplasm; whilst in NIH3T3 (mouse fibroblast cells), Usp15 localised in the cytoplasm and was enriched proximal to the plasma membrane (Soboleva et al, 2005). Interestingly, GFP-tagged USP15 (isoform USP15-203) adopts a largely cytoplasmic distribution in human cancer cell lines (Urbé, unpublished observation).…”

Section: Localisationmentioning

confidence: 99%

USP15 (ubiquitin specific peptidase 15)

Faronato¹,

Urbé²,

Coulson³

2012

Atlas of Genetics and Cytogenetics in Oncology and Haematology

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IdentityOther names: KIAA0529; UNPH4; Unph-2 HGNC (Hugo): USP15 Location: 12q14.1 DNA/RNANote USP15 is a member of the ubiquitin-specific protease (USP) family; these cysteine proteases comprise the largest sub-group of deubiquitinase enzymes (DUBs). USP15 cleaves the isopeptide bonds of polyubiquitin chains, and can cleave linear ubiquitin fusion proteins (Baker et al., 1999). DescriptionThe USP15 gene spans 145 kb of genomic DNA. TranscriptionFour transcripts of the human USP15 gene are described by Ensembl and are summarized in the accompanying diagram and table. According to Entrezgene, USP15 encodes a single reference sequence mRNA of 4611bp (NM_006313.1) composed of 21 exons, which corresponds to USP15-203. However, three other USP15 splice variants utilise several alternative-splicing sites between exon 5 and exon 7 of this reference sequence. USP15-201, a 4698 bp mRNA comprised of 22 exons, is expressed at similar levels to the reference sequence (Angelats et al., 2003). Expression of the remaining variants, USP15-204 and the truncated USP15-202, is less well studied.Schematic illustrating four human USP15 transcripts. The USP15 reference sequence mRNA (USP15-203) and three alternative splice variants are illustrated. The approximate position and size of exons within the USP15 gene, according to Ensembl, is shown for each splice variant. Schematic illustrating four human USP15 isoforms. The domain structure is shown for the reference sequence protein (USP15-203) and three alternative isoforms according to Ensembl. DUSP, domain present in ubiquitin-specific proteases; UBL, ubiquitin-like fold; UCH, ubiquitin carboxyl-terminal hydrolase. The cysteine motifs that form the zinc-binding site are shown in purple and the amino acids comprising the catalytic triad are shown in red. The approximate location of nuclear export sequences (triangles) and a putative nuclear localisation signal (inverted triangle) are shown above isoform USP15-203. Differences in amino acid sequence between isoforms are shown in light blue. The UCH is absent in isoform USP15-202, but USP15-201, USP15-203 and USP15-204 are predicted to be catalytically active. USP15 (ubiquitin specific peptidase 15)

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Nuclear-Cytoplasmic Shuttling of the Oncogenic Mouse UNP/USP4 Deubiquitylating Enzyme

Cited by 44 publications

References 42 publications

The Ubiquitin-Specific Protease Usp4 Regulates the Cell Surface Level of the A2a Receptor

The Ubiquitin-Specific Protease Usp4 Regulates the Cell Surface Level of the A2a Receptor

Solution Structure of the Human Ubiquitin-specific Protease 15 DUSP Domain

USP15 (ubiquitin specific peptidase 15)

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