Language：English   Publishing type：Research paper (scientific journal)  

Tau aggregates in neurons of brain lesions is a hallmark pathology of tauopathies, including Alzheimer's disease (AD). Recent studies suggest that the RNA-binding protein TIA1 initiates Tau aggregation by inducing the formation of stress granules (SGs) containing Tau. SGs are stress-inducible cytoplasmic protein aggregates containing many RNA-binding proteins that has been implicated as an initial site of multiple pathogenic protein aggregates in several neurodegenerative diseases. In this study, we found that ubiquitin-specific protease 10 (USP10) is a critical factor for the formation of Tau/TIA1/USP10-positive SGs. Proteasome inhibition or TIA1-overexpression in HT22 neuronal cells induced the formation of TIA1/Tau-positive SGs, and the formations were severely attenuated by depletion of USP10. In addition, the overexpression of USP10 without stress stimuli in HT22 cells induced TIA1/Tau/USP10-positive SGs in a deubiquitinase-independent manner. In AD brain lesions, USP10 was colocalized with Tau aggregates in the cell body of neurons. The present findings suggest that USP10 plays a key role in the initiation of pathogenic Tau aggregation in AD through SG formation.

DOI： 10.1038/s41598-019-47033-7

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Language：English   Publishing type：Research paper (scientific journal)  

Accumulation of ubiquitinated proteins is cytotoxic, but cells inactivate these cytotoxicities by inducing aggresome formation. We found that ubiquitin-specific protease 10 (USP10) inhibits ubiquitinated protein-induced apoptosis by inducing aggresome formation. USP10 interacted with the ubiquitin receptor p62 and the interaction augmented p62-dependent ubiquitinated protein aggregation and aggresome formation, thereby cooperatively inhibiting apoptosis. We provide evidence that USP10/p62-induced protein aggregates inhibit proteasome activity, which increases the amount of ubiquitinated proteins and promotes aggresome formation. USP10 induced aggresomes containing α-synuclein, a pathogenic protein in Parkinson disease, in cultured cells. In Parkinson disease brains, USP10 was colocalized with α-synuclein in the disease-linked aggresome-like inclusion Lewy bodies, suggesting that USP10 inhibits α-synuclein-induced neurotoxicity by promoting Lewy body formation. Collectively, these findings suggest that USP10 is a critical factor to control protein aggregation, aggresome formation, and cytotoxicity in protein-aggregation-related diseases.

DOI： 10.1016/j.isci.2018.11.006

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

The cellular proteostasis network integrates the protein folding and clearance machineries in multiple sub-cellular compartments of the eukaryotic cell. The endoplasmic reticulum (ER) is the site of synthesis and folding of membrane and secretory proteins. A distinctive feature of the ER is its tightly controlled redox homeostasis necessary for the formation of inter-and intra-molecular disulphide bonds. Employing genetically encoded in vivo sensors reporting on the redox state in an organelle-specific manner, we show in the nematode Caenorhabditis elegans that the redox state of the ER is subject to profound changes during worm lifetime. In young animals, the ER is oxidizing and this shifts towards reducing conditions during ageing, whereas in the cytosol the redox state becomes more oxidizing with age. Likewise, the redox state in the cytosol and the ER change in an opposing manner in response to proteotoxic challenges in C. elegans and in HeLa cells revealing conservation of redox homeostasis. Moreover, we show that organelle redox homeostasis is regulated across tissues within C. elegans providing a new measure for organismal fitness.

DOI： 10.15252/embj.201591711

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

In the early secretory compartment (ESC), a network of chaperones and enzymes assists oxidative folding of nascent proteins. Ero1 flavoproteins oxidize protein disulfide isomerase (PDI), generating H2O2 as a byproduct. Peroxiredoxin 4 (Prx4) can utilize luminal H2O2 to oxidize PDI, thus favoring oxidative folding while limiting oxidative stress. Interestingly, neither ER oxidase contains known ER retention signal(s), raising the question of how cells prevent their secretion. Here we show that the two proteins share similar intracellular localization mechanisms. Their secretion is prevented by sequential interactions with PDI and ERp44, two resident proteins of the ESC-bearing KDEL-like motifs. PDI binds preferentially Ero1 alpha, whereas ERp44 equally retains Ero1 alpha and Prx4. The different binding properties of Ero1 alpha and Prx4 increase the robustness of ER redox homeostasis.

DOI： 10.1074/jbc.M113.467845

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Authorship：Lead author   Language：English   Publisher：MARY ANN LIEBERT, INC  

Significance: The endoplasmic reticulum (ER), the port of entry into the secretory pathway, is a complex organelle that performs many fundamental functions, including protein synthesis and quality control, Ca2+ storage and signaling. Redox homeostasis is of paramount importance for allowing the efficient folding of secretory proteins, most of which contain essential disulfide bonds. Recent Advances: revealed that an intricate protein network sustains the processes of disulfide bond formation and reshuffling in the ER. Remarkably, H2O2, which is a known by-product of Ero1 flavoproteins in cells, is utilized by peroxiredoxin-4 and glutathione peroxidases-7 and -8, which reside in the mammalian secretory compartment and further fuel oxidative protein folding while limiting oxidative damage. Critical Issues: that remain to be addressed are the sources, diffusibility and signaling role(s) of H2O2 in and between organelles and cells, how the emerging redundancy in the systems is coupled to precise regulation, and how the distinct pathways operating in the early secretory compartment are integrated with one another. Future Directions: A further dissection of the pathways that integrate folding, redox homeostasis, and signaling in the early secretory pathway may allow to manipulate protein homeostasis and survival-death decisions in degenerative diseases or cancer. Antioxid. Redox Signal. 16, 763-771.

DOI： 10.1089/ars.2011.4238

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Presentation type：Poster presentation  

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Presentation type：Oral presentation (general)  

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Presentation type：Poster presentation  

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Presentation type：Oral presentation (general)  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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Presentation type：Poster presentation  

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