scholarly journals A therapeutic dose of doxorubicin activates ubiquitin-proteasome system-mediated proteolysis by acting on both the ubiquitination apparatus and proteasome

2008 ◽  
Vol 295 (6) ◽  
pp. H2541-H2550 ◽  
Author(s):  
Jinbao Liu ◽  
Hanqiao Zheng ◽  
Mingxin Tang ◽  
Youn-Chul Ryu ◽  
Xuejun Wang
Keyword(s):  
Critical Role ◽  
Proteasome Inhibition ◽  
Ubiquitin Proteasome System ◽  
Underlying Mechanism ◽  
3T3 Cells ◽  
New Findings ◽  
Relevant Dose ◽  
Ubiquitin Proteasome ◽  
Endogenous Substrates

The ubiquitin proteasome system (UPS) degrades abnormal proteins and most unneeded normal proteins, thereby playing a critical role in protein homeostasis in the cell. Proteasome inhibition is effective in treating certain forms of cancer, while UPS dysfunction is increasingly implicated in the pathogenesis of many severe and yet common diseases. It has been previously shown that doxorubicin (Dox) enhances the degradation of a UPS surrogate substrate in mouse hearts. To address the underlying mechanism, in the present study, we report that 1) Dox not only enhances the degradation of an exogenous UPS reporter (GFPu) but also antagonizes the proteasome inhibitor-induced accumulation of endogenous substrates (e.g., β-catenin and c-Jun) of the UPS in cultured NIH 3T3 cells and cardiomyocytes; 2) Dox facilitates the in vitro degradation of GFPu and c-Jun by the reconstituted UPS via the enhancement of proteasomal function; 3) Dox at a therapeutically relevant dose directly stimulates the peptidase activities of purified 20S proteasomes; and 4) Dox increases, whereas proteasome inhibition decreases, E3 ligase COOH-terminus of heat shock protein cognate 70 in 3T3 cells via a posttranscriptional mechanism. These new findings suggest that Dox activates the UPS by acting directly on both the ubiquitination apparatus and proteasome.

scholarly journals Interaction of U-box E3 ligase SNEV with PSMB4, the β7 subunit of the 20 S proteasome

2005 ◽  
Vol 388 (2) ◽  
pp. 593-603 ◽  
Author(s):  
Marlies LÖSCHER ◽  
Klaus FORTSCHEGGER ◽  
Gustav RITTER ◽  
Martina WOSTRY ◽  
Regina VOGLAUER ◽  
...  
Keyword(s):  
Immunofluorescence Microscopy ◽  
E3 Ligase ◽  
Proteasome Inhibition ◽  
Ubiquitin Proteasome System ◽  
E3 Ligases ◽  
Ubiquitin Proteasome Pathway ◽  
Ubiquitin Proteasome ◽  
Proteasome Pathway

Recognition of specific substrates for degradation by the ubiquitin–proteasome pathway is ensured by a cascade of ubiquitin transferases E1, E2 and E3. The mechanism by which the target proteins are transported to the proteasome is not clear, but two yeast E3s and one mammalian E3 ligase seem to be involved in the delivery of targets to the proteasome, by escorting them and by binding to the 19 S regulatory particle of the proteasome. In the present study, we show that SNEV (senescence evasion factor), a protein with in vitro E3 ligase activity, which is also involved in DNA repair and splicing, associates with the proteasome by directly binding to the β7 subunit of the 20 S proteasome. Upon inhibition of proteasome activity, SNEV does not accumulate within the cells although its co-localization with the proteasome increases significantly. Since immunofluorescence microscopy also shows increased co-localization of SNEV with ubiquitin after proteasome inhibition, without SNEV being ubiquitinated by itself, we suggest that SNEV shows E3 ligase activity not only in vitro but also in vivo and escorts its substrate to the proteasome. Since the yeast homologue of SNEV, Prp19, also interacts with the yeast β7 subunit of the proteasome, this mechanism seems to be conserved during evolution. Therefore these results support the hypothesis that E3 ligases might generally be involved in substrate transport to the proteasome. Additionally, our results provide the first evidence for a physical link between components of the ubiquitin–proteasome system and the spliceosome.

scholarly journals Long Non-Coding RNA CYP4B1-PS1-001 Inhibits Proliferation and Fibrosis in Diabetic Nephropathy by Interacting with Nucleolin

2018 ◽  
Vol 49 (6) ◽  
pp. 2174-2187 ◽  
Author(s):  
Suyu Wang ◽  
Xin Chen ◽  
Min Wang ◽  
Di Yao ◽  
Tianyu Chen ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
Rna Binding ◽  
Mesangial Cells ◽  
Critical Role ◽  
Underlying Mechanism ◽  
Non Coding Rna ◽  
Ubiquitin Proteasome ◽  
Long Non Coding Rna

Background/Aims: Our previous studies demonstrated that a novel long non-coding RNA, CYP4B1-PS1-001, was significantly downregulated in early diabetic nephropathy in vivo and in vitro, and CYP4B1-PS1-001 overexpression could inhibit the proliferation and fibrosis of mouse mesangial cells (MMCs). However, the underlying mechanism of the CYP4B1-PS1-001-mediated regulation of proliferation and fibrosis in diabetic nephropathy remains undetermined. Methods: RNA-protein pull-down assay, RNA-binding protein immunoprecipitation, and mass spectrometry were used to investigate CYP4B1-PS1-001 interacted with the upregulated protein nucleolin (NCL). siRNA method was applied to knockdown NCL in MMCs, the interaction between CYP4B1-PS1-001 and NCL were determined by Western blot analysis and RT-qPCR. The effect of CYP4B1-PS1-001 in the regulation of NCL was detected by cycloheximide (CHX) and ubiquitination assays. Results: We found that CYP4B1-PS1-001 interacts with NCL, and CYP4B1-PS1-001 inhibits the proliferation and fibrosis of MMCs depending on interaction with NCL. Furthermore, degradation of CYP4B1-PS1-001-associated NCL was mediated by a ubiquitin proteasome-dependent pathway. Conclusion: Our study provides evidence that CYP4B1-PS1-001 regulates the ubiquitination and degradation of NCL and thereby plays a critical role in the proliferation and fibrosis of MMCs, indicating that CYP4B1-PS1-001 and NCL may be promising prognostic biomarkers and molecular targets for the treatment of diabetic nephropathy.

scholarly journals Breakdown of Filamentous Myofibrils by the UPS–Step by Step

Biomolecules ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 110
Author(s):  
Dina Aweida ◽  
Shenhav Cohen
Keyword(s):  
Protein Quality ◽  
Protein Structures ◽  
Ubiquitin Proteasome System ◽  
Surface Proteins ◽  
Catalytic Core ◽  
Complex Protein ◽  
Ubiquitin Proteasome ◽  
Aaa Atpases

Protein degradation maintains cellular integrity by regulating virtually all biological processes, whereas impaired proteolysis perturbs protein quality control, and often leads to human disease. Two major proteolytic systems are responsible for protein breakdown in all cells: autophagy, which facilitates the loss of organelles, protein aggregates, and cell surface proteins; and the ubiquitin-proteasome system (UPS), which promotes degradation of mainly soluble proteins. Recent findings indicate that more complex protein structures, such as filamentous assemblies, which are not accessible to the catalytic core of the proteasome in vitro, can be efficiently degraded by this proteolytic machinery in systemic catabolic states in vivo. Mechanisms that loosen the filamentous structure seem to be activated first, hence increasing the accessibility of protein constituents to the UPS. In this review, we will discuss the mechanisms underlying the disassembly and loss of the intricate insoluble filamentous myofibrils, which are responsible for muscle contraction, and whose degradation by the UPS causes weakness and disability in aging and disease. Several lines of evidence indicate that myofibril breakdown occurs in a strictly ordered and controlled manner, and the function of AAA-ATPases is crucial for their disassembly and loss.

scholarly journals Immunoproteasome Function in Normal and Malignant Hematopoiesis

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1577
Author(s):  
Nuria Tubío-Santamaría ◽  
Frédéric Ebstein ◽  
Florian H. Heidel ◽  
Elke Krüger
Keyword(s):  
Proteasome Inhibition ◽  
Ubiquitin Proteasome System ◽  
Hematologic Malignancies ◽  
Protein Homeostasis ◽  
Efficacy And Safety ◽  
Hematopoietic System ◽  
Oxidized Proteins ◽  
Attractive Therapeutic Target ◽  
Ubiquitin Proteasome ◽  
Early Phases

The ubiquitin–proteasome system (UPS) is a central part of protein homeostasis, degrading not only misfolded or oxidized proteins but also proteins with essential functions. The fact that a healthy hematopoietic system relies on the regulation of protein homeostasis and that alterations in the UPS can lead to malignant transformation makes the UPS an attractive therapeutic target for the treatment of hematologic malignancies. Herein, inhibitors of the proteasome, the last and most important component of the UPS enzymatic cascade, have been approved for the treatment of these malignancies. However, their use has been associated with side effects, drug resistance, and relapse. Inhibitors of the immunoproteasome, a proteasomal variant constitutively expressed in the cells of hematopoietic origin, could potentially overcome the encountered problems of non-selective proteasome inhibition. Immunoproteasome inhibitors have demonstrated their efficacy and safety against inflammatory and autoimmune diseases, even though their development for the treatment of hematologic malignancies is still in the early phases. Various immunoproteasome inhibitors have shown promising preliminary results in pre-clinical studies, and one inhibitor is currently being investigated in clinical trials for the treatment of multiple myeloma. Here, we will review data on immunoproteasome function and inhibition in hematopoietic cells and hematologic cancers.

scholarly journals A Yeast-Based Functional Assay to Study Plant N-Degron – N-Recognin Interactions

2022 ◽  
Vol 12 ◽  
Author(s):  
Aida Kozlic ◽  
Nikola Winter ◽  
Theresia Telser ◽  
Jakob Reimann ◽  
Katrin Rose ◽  
...  
Keyword(s):  
Ubiquitin Proteasome System ◽  
Functional Assay ◽  
The Novel ◽  
In Planta ◽  
Amino Terminal ◽  
Weak Binding ◽  
Ubiquitin Conjugating Enzyme ◽  
Ubiquitin Proteasome ◽  
The Stability

The N-degron pathway is a branch of the ubiquitin-proteasome system where amino-terminal residues serve as degradation signals. In a synthetic biology approach, we expressed ubiquitin ligase PRT6 and ubiquitin conjugating enzyme 2 (AtUBC2) from Arabidopsis thaliana in a Saccharomyces cerevisiae strain with mutation in its endogenous N-degron pathway. The two enzymes re-constitute part of the plant N-degron pathway and were probed by monitoring the stability of co-expressed GFP-linked plant proteins starting with Arginine N-degrons. The novel assay allows for straightforward analysis, whereas in vitro interaction assays often do not allow detection of the weak binding of N-degron recognizing ubiquitin ligases to their substrates, and in planta testing is usually complex and time-consuming.

scholarly journals The Ubiquitin-Proteasome System Does Not Regulate the Degradation of Porcine β-Microseminoprotein during Sperm Capacitation

2020 ◽  
Vol 21 (11) ◽  
pp. 4151
Author(s):  
Lucie Tumova ◽  
Michal Zigo ◽  
Peter Sutovsky ◽  
Marketa Sedmikova ◽  
Pavla Postlerova
Keyword(s):  
Seminal Plasma ◽  
Plasma Proteins ◽  
Protein Composition ◽  
Surface Protein ◽  
Ubiquitin Proteasome System ◽  
Sperm Capacitation ◽  
Sperm Surface ◽  
Ubiquitin Proteasome ◽  
Seminal Plasma Proteins

Sperm capacitation, one of the key events during successful fertilization, is associated with extensive structural and functional sperm remodeling, beginning with the modification of protein composition within the sperm plasma membrane. The ubiquitin-proteasome system (UPS), a multiprotein complex responsible for protein degradation and turnover, participates in capacitation events. Previous studies showed that capacitation-induced shedding of the seminal plasma proteins such as SPINK2, AQN1, and DQH from the sperm surface is regulated by UPS. Alterations in the sperm surface protein composition also relate to the porcine β-microseminoprotein (MSMB/PSP94), seminal plasma protein known as immunoglobulin-binding factor, and motility inhibitor. MSMB was detected in the acrosomal region as well as the flagellum of ejaculated boar spermatozoa, while the signal disappeared from the acrosomal region after in vitro capacitation (IVC). The involvement of UPS in the MSMB degradation during sperm IVC was studied using proteasomal interference and ubiquitin-activating enzyme (E1) inhibiting conditions by image-based flow cytometry and Western blot detection. Our results showed no accumulation of porcine MSMB either under proteasomal inhibition or under E1 inhibiting conditions. In addition, the immunoprecipitation study did not detect any ubiquitination of sperm MSMB nor was MSMB detected in the affinity-purified fraction containing ubiquitinated sperm proteins. Based on our results, we conclude that UPS does not appear to be the regulatory mechanism in the case of MSMB and opening new questions for further studies. Thus, the capacitation-induced processing of seminal plasma proteins on the sperm surface may be more complex than previously thought, employing multiple proteolytic systems in a non-redundant manner.

scholarly journals Effects of ubiquitin C-terminal hydrolase L1 deficiency on mouse ova

Reproduction ◽  
2012 ◽  
Vol 143 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Sayaka Koyanagi ◽  
Hiroko Hamasaki ◽  
Satoshi Sekiguchi ◽  
Kenshiro Hara ◽  
Yoshiyuki Ishii ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Proteomic Analysis ◽  
Ubiquitin Proteasome System ◽  
Underlying Mechanism ◽  
Wild Type ◽  
Transmission Electron ◽  
Ubiquitin Proteasome

Maternal proteins are rapidly degraded by the ubiquitin–proteasome system during oocyte maturation in mice. Ubiquitin C-terminal hydrolase L1 (UCHL1) is highly and specifically expressed in mouse ova and is involved in the polyspermy block. However, the role of UCHL1 in the underlying mechanism of polyspermy block is poorly understood. To address this issue, we performed a comprehensive proteomic analysis to identify maternal proteins that were relevant to the role of UCHL1 in mouse ova using UCHL1-deficientgad. Furthermore, we assessed morphological features ingadmouse ova using transmission electron microscopy. NACHT, LRR, and PYD domain-containing (NALP) family proteins and endoplasmic reticulum (ER) chaperones were identified by proteomic analysis. We also found that the ‘maternal antigen that embryos require’ (NLRP5 (MATER)) protein level increased significantly ingadmouse ova compared with that in wild-type mice. In an ultrastructural study,gadmouse ova contained less ER in the cortex than in wild-type mice. These results provide new insights into the role of UCHL1 in the mechanism of polyspermy block in mouse ova.

scholarly journals The proteasome controls presynaptic differentiation through modulation of an on-site pool of polyubiquitinated conjugates

2016 ◽  
Vol 212 (7) ◽  
pp. 789-801 ◽  
Author(s):  
Maria J. Pinto ◽  
Pedro L. Alves ◽  
Luís Martins ◽  
Joana R. Pedro ◽  
Hyun R. Ryu ◽  
...  
Keyword(s):  
Synaptic Vesicles ◽  
Proteasome Inhibition ◽  
Ubiquitin Proteasome System ◽  
Presynaptic Terminal ◽  
Ubiquitinated Proteins ◽  
Presynaptic Differentiation ◽  
Intrinsic Mechanism ◽  
Ubiquitin Proteasome ◽  
Presynaptic Assembly ◽  
Local Modulation

Differentiation of the presynaptic terminal is a complex and rapid event that normally occurs in spatially specific axonal regions distant from the soma; thus, it is believed to be dependent on intra-axonal mechanisms. However, the full nature of the local events governing presynaptic assembly remains unknown. Herein, we investigated the involvement of the ubiquitin–proteasome system (UPS), the major degradative pathway, in the local modulation of presynaptic differentiation. We found that proteasome inhibition has a synaptogenic effect on isolated axons. In addition, formation of a stable cluster of synaptic vesicles onto a postsynaptic partner occurs in parallel to an on-site decrease in proteasome degradation. Accumulation of ubiquitinated proteins at nascent sites is a local trigger for presynaptic clustering. Finally, proteasome-related ubiquitin chains (K11 and K48) function as signals for the assembly of presynaptic terminals. Collectively, we propose a new axon-intrinsic mechanism for presynaptic assembly through local UPS inhibition. Subsequent on-site accumulation of proteins in their polyubiquitinated state triggers formation of presynapses.

scholarly journals USP14 Inhibition Regulates Tumorigenesis by Inducing Autophagy in Lung Cancer In Vitro

2019 ◽  
Vol 20 (21) ◽  
pp. 5300 ◽  
Author(s):  
Kyung Ho Han ◽  
Minseok Kwak ◽  
Tae Hyeong Lee ◽  
Min-soo Park ◽  
In-ho Jeong ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Ubiquitin Proteasome System ◽  
Migration And Invasion ◽  
Deubiquitinating Enzyme ◽  
Lung Tumorigenesis ◽  
Ubiquitin Chain ◽  
Specific Protease ◽  
Ubiquitin Proteasome ◽  
Autophagy Pathway

The ubiquitin–proteasome system is an essential regulator of several cellular pathways involving oncogenes. Deubiquitination negatively regulates target proteins or substrates linked to both hereditary and sporadic forms of cancer. The deubiquitinating enzyme ubiquitin-specific protease 14 (USP14) is associated with proteasomes where it trims the ubiquitin chain on the substrate. Here, we found that USP14 is highly expressed in patients with lung cancer. We also demonstrated that USP14 inhibitors (IU1-47 and siRNA-USP14) significantly decreased cell proliferation, migration, and invasion in lung cancer. Remarkably, we found that USP14 negatively regulates lung tumorigenesis not only through apoptosis but also through the autophagy pathway. Our findings suggest that USP14 plays a crucial role in lung tumorigenesis and that USP14 inhibitors are potent drugs in lung cancer treatment.

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