scholarly journals Co-Transmission of Alpha-Synuclein and TPPP/p25 Inhibits Their Proteolytic Degradation in Human Cell Models

2021 ◽  
Vol 8 ◽  
Author(s):  
Attila Lehotzky ◽  
Judit Oláh ◽  
János Tibor Fekete ◽  
Tibor Szénási ◽  
Edit Szabó ◽  
...  
Keyword(s):  
Cell Types ◽  
Ubiquitin Proteasome System ◽  
Alpha Synuclein ◽  
Human Cells ◽  
Proteolytic Degradation ◽  
Intrinsically Disordered ◽  
Cell Transmission ◽  
Key Factor ◽  
Ubiquitin Proteasome ◽  
Combined Strategy

The pathological association of alpha-synuclein (SYN) and Tubulin Polymerization Promoting Protein (TPPP/p25) is a key factor in the etiology of synucleinopathies. In normal brains, the intrinsically disordered SYN and TPPP/p25 are not found together but exist separately in neurons and oligodendrocytes, respectively; in pathological states, however, they are found in both cell types due to their cell-to-cell transmission. The autophagy degradation of the accumulated/assembled SYN has been considered as a potential therapeutic target. We have shown that the hetero-association of SYN with TPPP/p25 after their uptake from the medium by human cells (which mimics cell-to-cell transmission) inhibits both their autophagy- and the ubiquitin-proteasome system-derived elimination. These results were obtained by ELISA, Western blot, FACS and immunofluorescence confocal microscopy using human recombinant proteins and living human cells; ANOVA statistical analysis confirmed that TPPP/p25 counteracts SYN degradation by hindering the autophagy maturation at the stage of LC3B-SQSTM1/p62-derived autophagosome formation and its fusion with lysosome. Recently, fragments of TPPP/p25 that bind to the interface between the two hallmark proteins have been shown to inhibit their pathological assembly. In this work, we show that the proteolytic degradation of SYN on its own is more effective than when it is complexed with TPPP/p25. The combined strategy of TPPP/p25 fragments and proteolysis may ensure prevention and/or elimination of pathological SYN assemblies.

scholarly journals Ochratoxin A Sequentially Activates Autophagy and the Ubiquitin-Proteasome System

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 615
Author(s):  
Akpinar ◽  
Kahraman ◽  
Yaman
Keyword(s):  
Ochratoxin A ◽  
Early Time ◽  
Human Kidney ◽  
Cell Types ◽  
Ubiquitin Proteasome System ◽  
Mouse Embryonic Fibroblast ◽  
Proteasomal Activity ◽  
Ubiquitin Proteasome ◽  
Autophagic Activity ◽  
Sustained Activation

Ochratoxin A (OTA) is a carcinogenic mycotoxin, which is produced by Aspergillus and Penicillium genera of fungi and commonly contaminates food and feed. We and others have previously shown that OTA causes sustained activation of PI3K/AKT and MAPK/ERK1-2 signaling pathways in different cell types and animal models. Given the close relationship between cellular signaling activity and protein stability, we were curious whether increased PI3K/AKT and MAPK/ERK1-2 signaling may be the result of OTA-stimulated alterations in proteolytic activity. We show that both of the major proteolytic systems, autophagy, and the ubiquitin-proteasome system (UPS), are activated upon OTA exposure in human kidney proximal tubule HK-2 and mouse embryonic fibroblast (MEF) cells. OTA stimulates transient autophagic activity at early time points of treatment but autophagic activity subsides after 6 h even in the sustained presence of OTA. Interestingly, OTA exposure also results in increased cell death in wild-type MEF cells but not in autophagy-halted Atg5-deficient cells, suggesting that autophagy exerts a pro-death effect on OTA-induced cytotoxicity. In addition, prolonged OTA exposure decreased ubiquitinated protein levels by increasing proteasomal activity. Using purified and cellular proteasomes, we observed enhanced chymotrypsin-, caspase-, and trypsin-like activities of the 26S but not the 20S proteasome in the presence of OTA. However, in the cellular context, increased proteasomal activity depended on prior induction of autophagy. Our results suggest that autophagy and subsequent UPS activation are responsible for sustained activation of PI3K/AKT and MAPK/ERK1-2 pathways through regulating the levels of critical phosphatases VHR/DUSP3, DUSP4, and PHLPP, which are known to be involved in OTA toxicity and carcinogenicity.

Use of Ubiquitin-Proteasome System Profiling for Differentiating Between Various Leukemic Processes.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4712-4712
Author(s):  
Ke Zhang ◽  
Hagop M. Kantarjian ◽  
Wanlong Ma ◽  
XI Zhang ◽  
Xiuqiang Wang ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Direct Analysis ◽  
Cell Types ◽  
Ubiquitin Proteasome System ◽  
Lymphocytic Leukemia ◽  
Ubiquitin Proteasome

Abstract Abstract 4712 The ubiquitin-proteasome system (UPS) plays a major role in cell homeostasis in normal and neoplastic states. Expression and function of the UPS system vary with the specific characteristics of individual cell types, suggesting that determination of UPS “signatures” could be useful in identifying various cell populations. Since direct analysis of cancer cells is often problematic, even in hematologic diseases, we explored the potential of using UPS signatures in plasma to differentiate between various leukemias. We first analyzed plasma UPS profiles of patients with acute myeloid leukemia (AML; n=111), acute lymphoblastic leukemia (ALL; n=29), advanced myelodysplastic syndrome (MDS; n=20), chronic lymphocytic leukemia (CLL; n=118), or chronic myeloid leukemia (CML; n=128; 46 in accelerated/blast crisis [ACC/BL], 82 in chronic phase), and 85 healthy control subjects. Plasma levels of proteasome, ubiquitin (poly-ubiquitin), and the 3 proteasome enzymatic activities (chymotrypsin-like [Ch-L], caspase-like [Cas-L], trypsin-like [Tr-L]) were measured. Specific activities were calculated by normalizing each of the 3 enzyme activities to the levels of proteasome protein in plasma (Ch-L/p, Cas-L/p, and Tr-L/p). These 8 variables were used in multivariate logistic regression models to differentiate between leukemic processes. UPS signatures provided clear differentiation between patients with a leukemic process and normal controls (AUC=0.991), using 6 different variables (Tr-L/P, Ch-L, Ch-L/p, Cas-L, Cas-L/P, ubiquitin). Distinguishing between acute (AML, ALL, MDS) and chronic (CML, CLL) processes was less efficient (AUC=0.853 using Tr-L, Tr-L/P, Cas-L/P, Ch-L/P, proteasome, Ch-L), likely due to the high proportion (36%) of CML patients in ACC/BL phase. However, UPS signatures generally yielded powerful differentiation between individual leukemias (Table). MDS was not well differentiated from AML (AUC=0.791), reflecting the significant biological overlap of these diseases. These data support the potential usefulness of the UPS profile to aid in the differential diagnosis of various leukemias. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Role of the COP9 Signalosome (CSN) in Cardiovascular Diseases

Biomolecules ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 217 ◽  
Author(s):  
Milic ◽  
Tian ◽  
Bernhagen
Keyword(s):  
Cardiovascular Diseases ◽  
Molecular Mechanisms ◽  
Three Dimensional ◽  
Cell Types ◽  
Ubiquitin Proteasome System ◽  
Cop9 Signalosome ◽  
Ring E3 Ligase ◽  
Ubiquitin Proteasome ◽  
Underlying Mechanisms ◽  
Isopeptidase Activity

The constitutive photomorphogenesis 9 (COP9) signalosome (CSN) is an evolutionarily conserved multi-protein complex, consisting of eight subunits termed CSN1-CSN8. The main biochemical function of the CSN is the control of protein degradation via the ubiquitin-proteasome-system through regulation of cullin-RING E3-ligase (CRL) activity by deNEDDylation of cullins, but the CSN also serves as a docking platform for signaling proteins. The catalytic deNEDDylase (isopeptidase) activity of the complex is executed by CSN5, but only efficiently occurs in the three-dimensional architectural context of the complex. Due to its positioning in a central cellular pathway connected to cell responses such as cell-cycle, proliferation, and signaling, the CSN has been implicated in several human diseases, with most evidence available for a role in cancer. However, emerging evidence also suggests that the CSN is involved in inflammation and cardiovascular diseases. This is both due to its role in controlling CRLs, regulating components of key inflammatory pathways such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and complex-independent interactions of subunits such as CSN5 with inflammatory proteins. In this case, we summarize and discuss studies suggesting that the CSN may have a key role in cardiovascular diseases such as atherosclerosis and heart failure. We discuss the implicated molecular mechanisms ranging from inflammatory NF-κB signaling to proteotoxicity and necrosis, covering disease-relevant cell types such as myeloid and endothelial cells or cardiomyocytes. While the CSN is considered to be disease-exacerbating in most cancer entities, the cardiovascular studies suggest potent protective activities in the vasculature and heart. The underlying mechanisms and potential therapeutic avenues will be critically discussed.

Natural alkaloid harmine promotes degradation of alpha-synuclein via PKA-mediated ubiquitin-proteasome system activation

Phytomedicine ◽  
2019 ◽  
Vol 61 ◽  
pp. 152842 ◽  
Author(s):  
Cui-Zan Cai ◽  
He-Feng Zhou ◽  
Ning-Ning Yuan ◽  
Ming-Yue Wu ◽  
Simon Ming-Yuen Lee ◽  
...  
Keyword(s):  
Ubiquitin Proteasome System ◽  
Alpha Synuclein ◽  
Ubiquitin Proteasome ◽  
Natural Alkaloid ◽  
System Activation

Ubiquitin‐proteasome system is responsible for the protection of yeast and human cells against methylmercury

2002 ◽  
Vol 16 (7) ◽  
pp. 709-711 ◽  
Author(s):  
Gi‐Wook Hwang ◽  
Takemitsu Furuchi ◽  
Akira Naganuma
Keyword(s):  
Ubiquitin Proteasome System ◽  
Human Cells ◽  
Ubiquitin Proteasome

scholarly journals Proteaphagy in Mammalian Cells Can Function Independent of ATG5/ATG7

2020 ◽  
Vol 19 (7) ◽  
pp. 1120-1131 ◽  
Author(s):  
Tatjana Goebel ◽  
Simone Mausbach ◽  
Andreas Tuermer ◽  
Heba Eltahir ◽  
Dominic Winter ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Mammalian Cells ◽  
Adaptor Proteins ◽  
Cell Types ◽  
Ubiquitin Proteasome System ◽  
Extracellular Proteins ◽  
Ubiquitin Proteasome ◽  
Native Gel ◽  
Chaperone Mediated Autophagy ◽  
Coenzym A

The degradation of intra- and extracellular proteins is essential in all cell types and mediated by two systems, the ubiquitin-proteasome system (UPS) and the autophagy-lysosome pathway. This study investigates the changes in autophagosomal and lysosomal proteomes upon inhibition of proteasomes by bortezomib (BTZ) or MG132. We find an increased abundance of more than 50 proteins in lysosomes of cells in which the proteasome is inhibited. Among those are dihydrofolate reductase (DHFR), β-Catenin and 3-hydroxy-3-methylglutaryl-coenzym-A (HMGCoA)-reductase. Because these proteins are known to be degraded by the proteasome they seem to be compensatorily delivered to the autophagosomal pathway when the proteasome is inactivated. Surprisingly, most of the proteins which show increased amounts in the lysosomes of BTZ or MG132 treated cells are proteasomal subunits. Thus an inactivated, non-functional proteasome is delivered to the autophagic pathway. Native gel electrophoresis shows that the proteasome reaches the lysosome intact and not disassembled. Adaptor proteins, which target proteasomes to autophagy, have been described in Arabidopsis, Saccharomyces and upon starvation in mammalians. However, in cell lines deficient of these proteins or their mammalian orthologues, respectively, the transfer of proteasomes to the lysosome is not impaired. Obviously, these proteins do not play a role as autophagy adaptor proteins in mammalian cells. We can also show that chaperone-mediated autophagy (CMA) does not participate in the proteasome delivery to the lysosomes. In autophagy-related (ATG)-5 and ATG7 deficient cells the delivery of inactivated proteasomes to the autophagic pathway was only partially blocked, indicating the existence of at least two different pathways by which inactivated proteasomes can be delivered to the lysosome in mammalian cells.

scholarly journals Promiscuous Roles of Autophagy and Proteasome in Neurodegenerative Proteinopathies

2020 ◽  
Vol 21 (8) ◽  
pp. 3028 ◽  
Author(s):  
Fiona Limanaqi ◽  
Francesca Biagioni ◽  
Stefano Gambardella ◽  
Pietro Familiari ◽  
Alessandro Frati ◽  
...  
Keyword(s):  
Protein Misfolding ◽  
Glycogen Synthase ◽  
Mammalian Target Of Rapamycin ◽  
Ubiquitin Proteasome System ◽  
Alpha Synuclein ◽  
Fused In Sarcoma ◽  
Complex Interactions ◽  
Morphological Studies ◽  
Transcription Factor Eb ◽  
Ubiquitin Proteasome

Alterations in autophagy and the ubiquitin proteasome system (UPS) are commonly implicated in protein aggregation and toxicity which manifest in a number of neurological disorders. In fact, both UPS and autophagy alterations are bound to the aggregation, spreading and toxicity of the so-called prionoid proteins, including alpha synuclein (α-syn), amyloid-beta (Aβ), tau, huntingtin, superoxide dismutase-1 (SOD-1), TAR-DNA-binding protein of 43 kDa (TDP-43) and fused in sarcoma (FUS). Recent biochemical and morphological studies add to this scenario, focusing on the coordinated, either synergistic or compensatory, interplay that occurs between autophagy and the UPS. In fact, a number of biochemical pathways such as mammalian target of rapamycin (mTOR), transcription factor EB (TFEB), Bcl2-associated athanogene 1/3 (BAG3/1) and glycogen synthase kinase beta (GSk3β), which are widely explored as potential targets in neurodegenerative proteinopathies, operate at the crossroad between autophagy and UPS. These biochemical steps are key in orchestrating the specificity and magnitude of the two degradation systems for effective protein homeostasis, while intermingling with intracellular secretory/trafficking and inflammatory pathways. The findings discussed in the present manuscript are supposed to add novel viewpoints which may further enrich our insight on the complex interactions occurring between cell-clearing systems, protein misfolding and propagation. Discovering novel mechanisms enabling a cross-talk between the UPS and autophagy is expected to provide novel potential molecular targets in proteinopathies.

Regulation of primary cilia formation by the ubiquitin–proteasome system

2016 ◽  
Vol 44 (5) ◽  
pp. 1265-1271 ◽  
Author(s):  
Robert F. Shearer ◽  
Darren N. Saunders
Keyword(s):  
Signal Transduction ◽  
Primary Cilium ◽  
Primary Cilia ◽  
Cell Types ◽  
Ubiquitin Proteasome System ◽  
Signal Transduction Pathways ◽  
Vertebrate Cell ◽  
Cilia Formation ◽  
Ubiquitin Proteasome ◽  
Novel Therapeutic

Primary cilia form at the surface of most vertebrate cell types, where they are essential signalling antennae for signal transduction pathways important for development and cancer, including Hedgehog. The importance of primary cilia in development is clearly demonstrated by numerous disorders (known as ciliopathies) associated with disrupted cilia formation (ciliogenesis). Recent advances describing functional regulators of the primary cilium highlight an emerging role for the ubiquitin–proteasome system (UPS) as a key regulator of ciliogenesis. Although there are well-documented examples of E3 ubiquitin ligases and deubiquitases in the regulation of cilia proteins, many putative components remain unvalidated. This review explores current understanding of how the UPS influences primary cilia formation, and also how recent screen data have identified more putative regulators of the UPS. Emerging research has identified many promising leads in the search for regulators of this important organelle and may identify potential novel therapeutic targets for intervention in cancer and other disease contexts.

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