Lys-63-linked Ubiquitination by E3 Ubiquitin Ligase Nedd4-1 Facilitates Endosomal Sequestration of Internalized α-Synuclein

Sugeno, Naoto; Hasegawa, Takafumi; Tanaka, Nobuyuki; Fukuda, Mitsunori; Wakabayashi, Keiji; Oshima, Ryuji; Konno, Masashi; Miura, Emiko; Kikuchi, Akio; Baba, Toru; Anan, Tadashi; Nakao, Mitsuyoshi; Geisler, Sven; Akiyama, Masashi; Takeda, Atsushi

doi:10.1074/jbc.m113.529461

Cited by 64 publications

(56 citation statements)

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“…37 However, this type of ubiquitination can promote or aid in the lysosomal-mediated degradation of substrate proteins, including transmembrane proteins such as LDL receptor and Class I molecule, 38–40 cytosolic proteins such as α-synuclein, 41 and nuclear proteins such as HIF1A. 42 Although EZH2 contains the minimum sequence of YXXØ motif (for lysosomal-mediated degradation of transmembrane proteins) including YAKV and YVGI at the C-terminal (data not shown), it is deficient of the pentpeptide sequence KFERQ, a sorting signal for lysosomal-mediated degradation of cytosolic proteins.…”

Section: Discussionmentioning

confidence: 99%

SKP2 loss destabilizes EZH2 by promoting TRAF6-mediated ubiquitination to suppress prostate cancer

Liu

et al. 2016

Oncogene

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EZH2 is crucial for the progression of prostate cancer (PCa) and castration-resistant prostate cancer (CRPC) through upregulation and activation of progenitor genes, as well as androgen receptor (AR)-target genes. However, the mechanisms by which EZH2 is regulated in PCa and CRPC remain elusive. Here we report that EZH2 is post-transcriptionally regulated by SKP2 in vitro in cultured cells and in vivo in mouse models. We observed aberrant upregulation of Skp2, Ezh2 and histone H3 lysine 27 trimethylation (H3K27me3) in both Pten null mouse embryonic fibroblasts (MEFs) and Pten null mouse prostate tissues. Loss of Skp2 resulted in a striking decrease of Ezh2 levels in Pten/Trp53 double-null MEFs and in prostate tumors of Pten/Trp53 double-null mutant mice. SKP2 knockdown decreased EZH2 levels in human PCa cells through upregulation of TRAF6-mediated and lysine(K) 63-linked ubiquitination of EZH2 for degradation. Ectopic expression of TRAF6 promoted the K63-linked ubiquitination of EZH2 to decrease EZH2 and H3K27me3 levels in PCa cells. In contrast, TRAF6 knockdown resulted in a reduced EZH2 ubiquitination with an increase of EZH2 and H3K27me3 levels in PCa cells. Furthermore, the catalytically dead mutant TRAF6 C70A abolished the TRAF6-mediated polyubiquitination of recombinant human EZH2 in vitro. Most importantly, a concurrent elevation of Skp2 and Ezh2 was found in CRPC tumors of Pten/Trp53 mutant mice, and expression levels of SKP2 and EZH2 were positively correlated in human PCa specimens. Taken together, our findings revealed a novel mechanism on EZH2 ubiquitination and an important signaling network of SKP2-TRAF6-EZH2/H3K27me3, and targeting SKP2-EZH2 pathway may be a promising therapeutic strategy for CRPC treatment.

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Section: Discussionmentioning

confidence: 99%

SKP2 loss destabilizes EZH2 by promoting TRAF6-mediated ubiquitination to suppress prostate cancer

Liu

et al. 2016

Oncogene

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“…Thus, normally in cells, K63-linked ubiquitin chains are continually being hydrolyzed by Usp8, which serves an important function in endosomal-lysosomal trafficking. We and others have previously shown that the ubiquitin ligase Nedd4 and its yeast ortholog Rsp5 conjugate K63-linked chains on α-synuclein, promoting its trafficking by the endosomal route (7,32,33), and that α-synuclein is enriched in endosomal compartments (34,35). At the synapse, Nedd4 is responsible for formation of K63-linked chains that is antagonized by Usp8 (36), and in vitro these enzymes have opposing activities on α-synuclein ubiquitination.…”

Section: Discussionmentioning

confidence: 99%

Deubiquitinase Usp8 regulates α-synuclein clearance and modifies its toxicity in Lewy body disease

Alexopoulou

Lang

Perrett

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

110

108

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In Parkinson’s disease, misfolded α-synuclein accumulates, often in a ubiquitinated form, in neuronal inclusions termed Lewy bodies. An important outstanding question is whether ubiquitination in Lewy bodies is directly relevant to α-synuclein trafficking or turnover and Parkinson’s pathogenesis. By comparative analysis in human postmortem brains, we found that ubiquitin immunoreactivity in Lewy bodies is largely due to K63-linked ubiquitin chains and markedly reduced in the substantia nigra compared with the neocortex. The ubiquitin staining in cells with Lewy bodies inversely correlated with the content and pathological localization of the deubiquitinase Usp8. Usp8 interacted and partly colocalized with α-synuclein in endosomal membranes and, both in cells and after purification, it deubiquitinated K63-linked chains on α-synuclein. Knockdown of Usp8 in the Drosophila eye reduced α-synuclein levels and α-synuclein–induced eye toxicity. Accordingly, in human cells, Usp8 knockdown increased the lysosomal degradation of α-synuclein. In the dopaminergic neurons of the Drosophila model, unlike knockdown of other deubiquitinases, Usp8 protected from α-synuclein–induced locomotor deficits and cell loss. These findings strongly suggest that removal of K63-linked ubiquitin chains on α-synuclein by Usp8 is a critical mechanism that reduces its lysosomal degradation in dopaminergic neurons and may contribute to α-synuclein accumulation in Lewy body disease.

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“…Despite the substantial role of endocytosis in the uptake process of αSYN, αSYN internalization was not completely blocked by the disruption of the endocytic machinery , indicating the existence of alternative mechanisms other than endocytosis. Indeed, there is evidence showing that fibrillar and non-fibrillar αSYN species were incorporated via the endocytic machinery, while an αSYN monomer directly passed through the plasma membrane Sugeno et al 2014). Unfortunately, it remains to be determined how αSYN crosses the cellular membrane; however, several possibilities have been postulated such as direct penetration (Ahn et al 2006), formation of annular, pore-like structures (Volles and Lansbury 2002), tunneling-nanotubes (Abounit et al 2016;Dieriks et al 2017), or macropinocytosis (Lee et al 2010b).…”

Section: How Does Exogenous α-Synuclein Get Into Cells?mentioning

confidence: 99%

Membrane Trafficking Illuminates a Path to Parkinson’s Disease

Hasegawa

Sugeno

Kikuchi

et al. 2017

Tohoku J. Exp. Med.

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Parkinson's disease (PD) is the second most common neurodegenerative disorder that is characterized by progressive movement disability and a variety of non-motor symptoms. The neuropathology of PD consists of the loss of dopaminergic neurons in the midbrain and the appearance of neuronal inclusions called Lewy bodies, which contain insoluble α-synuclein, a relatively small protein originally identified in association with synaptic vesicles in the presynaptic nerve terminals. Drugs that replenish dopamine can partly alleviate the motor symptoms, but they do not cure the disease itself. Therefore, there is an urgent need for disease modification in terms of the delay or prevention of neurodegeneration. Recent advances in genetic and biochemical studies have provided unifying conceptual frameworks of the pathogenesis of PD. Particularly, membrane trafficking has aroused special attention as an initiator or enhancer of the neurodegenerative process that leads to PD. Defects in the cellular trafficking pathway result in synaptic dysfunction and the accumulation of misfolded α -synuclein. Likewise, changes in intracellular sorting and degradation profoundly influence the cellular trafficking of misfolded proteins, thereby facilitating the cell-to-cell spreading of hazardous α-synuclein species in a prion-like manner. Here, we will review our current knowledge of the functional roles of membrane trafficking in PD and will discuss how this cellular process could induce or facilitate the functional and pathological alterations in this disease.

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Lys-63-linked Ubiquitination by E3 Ubiquitin Ligase Nedd4-1 Facilitates Endosomal Sequestration of Internalized α-Synuclein

Cited by 64 publications

References 50 publications

SKP2 loss destabilizes EZH2 by promoting TRAF6-mediated ubiquitination to suppress prostate cancer

SKP2 loss destabilizes EZH2 by promoting TRAF6-mediated ubiquitination to suppress prostate cancer

Deubiquitinase Usp8 regulates α-synuclein clearance and modifies its toxicity in Lewy body disease

Membrane Trafficking Illuminates a Path to Parkinson’s Disease

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