Searching for the boundaries: unlimited expansion of ubiquitin and ubiquitin-like signals in multiple cellular functions

2010 ◽  
Vol 38 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Bernat Crosas ◽  
Rosa Farràs ◽  
Gemma Marfany ◽  
Manuel S. Rodríguez ◽  
Timothy M. Thomson

The ubiquitin–proteasome field has matured, as is evident from the wide diversity of systems and mechanisms in which it participates and that are the subject of investigation, presented in the Ubiquitin–Proteasome System, Dynamics and Targeting meeting held in Barcelona, co-sponsored by the Biochemical Society, the Spanish Ministry of Science, the Spanish Research Council and the Catalan Academy of Sciences. Several of the aspects dealt with in the meeting are discussed in detail in the collection of review papers included in this issue of Biochemical Society Transactions. These papers reflect the importance of ubiquitin and ubiquitin-like modifiers as enormously versatile signalling entities that modulate and direct pathways in specific directions through modification-induced interactions. One conclusion from the meeting is that the field has become so rich and dense that, in order to be useful and informative, future meetings may need to focus on particular aspects of the ubiquitin–proteasome system.

Cancers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1579 ◽  
Author(s):  
Ainsley Mike Antao ◽  
Apoorvi Tyagi ◽  
Kye-Seong Kim ◽  
Suresh Ramakrishna

Since the discovery of the ubiquitin proteasome system (UPS), the roles of ubiquitinating and deubiquitinating enzymes (DUBs) have been widely elucidated. The ubiquitination of proteins regulates many aspects of cellular functions such as protein degradation and localization, and also modifies protein-protein interactions. DUBs cleave the attached ubiquitin moieties from substrates and thereby reverse the process of ubiquitination. The dysregulation of these two paramount pathways has been implicated in numerous diseases, including cancer. Attempts are being made to identify inhibitors of ubiquitin E3 ligases and DUBs that potentially have clinical implications in cancer, making them an important target in the pharmaceutical industry. Therefore, studies in medicine are currently focused on the pharmacological disruption of DUB activity as a rationale to specifically target cancer-causing protein aberrations. Here, we briefly discuss the pathophysiological and physiological roles of DUBs in key cancer-related pathways. We also discuss the clinical applications of promising DUB inhibitors that may contribute to the development of DUBs as key therapeutic targets in the future.


2010 ◽  
Vol 2 ◽  
pp. CMT.S2889
Author(s):  
Klaus Podar ◽  
Kenneth C. Anderson

The ubiquitin-proteasome-degradation system plays a key role in multiple cellular functions. Its deregulation is associated with the initiation and progression of human diseases including not only solid and hematologic malignancies but also neurologic and autoimmune disorders. This article discusses several novel mechanistic aspects of the ubiquitin-proteasome system. Moreover, it focuses on the development, mechanisms of action, and clinical experience with Bortezomib, the first in-class-proteasome inhibitor to enter the clinics. Finally, it summarizes novel approaches to specifically target distinct components within the highly complex and dynamic ubiquitin-proteasome machinery to ultimately further increase drug activity, as well as reduce drug resistance and adverse side effects.


2005 ◽  
Vol 41 ◽  
pp. 139-156 ◽  
Author(s):  
Julia Shackelford ◽  
Joseph S. Pagano

The ability of viruses to co-opt cell signalling pathways has, over millions of years of co-evolution, come to pervade nearly every facet of cellular functions. Recognition of the extent to which the ubiquitin–proteasome system can be directed or subverted by viruses is relatively recent. Viral products interact with, and adjust, the ubiquitin–proteasome machinery precisely and at many levels, and they do so at distinct stages of viral life-cycles. The implications for both cells and viruses are fundamental, and understanding viral strategies in this context opens up fascinating new areas for research that span from basic cell biology to therapeutic interventions against both viruses and malignancies.


2013 ◽  
Vol 304 (3) ◽  
pp. H337-H349 ◽  
Author(s):  
Justine Calise ◽  
Saul R. Powell

The ubiquitin proteasome system (UPS) has been the subject of intensive research over the past 20 years to define its role in normal physiology and in pathophysiology. Many of these studies have focused in on the cardiovascular system and have determined that the UPS becomes dysfunctional in several pathologies such as familial and idiopathic cardiomyopathies, atherosclerosis, and myocardial ischemia. This review presents a synopsis of the literature as it relates to the role of the UPS in myocardial ischemia. Studies have shown that the UPS is dysfunctional during myocardial ischemia, and recent studies have shed some light on possible mechanisms. Other studies have defined a role for the UPS in ischemic preconditioning which is best associated with myocardial ischemia and is thus presented here. Very recent studies have started to define roles for specific proteasome subunits and components of the ubiquitination machinery in various aspects of myocardial ischemia. Lastly, despite the evidence linking myocardial ischemia and proteasome dysfunction, there are continuing suggestions that proteasome inhibitors may be useful to mitigate ischemic injury. This review presents the rationale behind this and discusses both supportive and nonsupportive studies and presents possible future directions that may help in clarifying this controversy.


2018 ◽  
Vol 87 (1) ◽  
pp. 697-724 ◽  
Author(s):  
Jared A.M. Bard ◽  
Ellen A. Goodall ◽  
Eric R. Greene ◽  
Erik Jonsson ◽  
Ken C. Dong ◽  
...  

As the endpoint for the ubiquitin-proteasome system, the 26S proteasome is the principal proteolytic machine responsible for regulated protein degradation in eukaryotic cells. The proteasome's cellular functions range from general protein homeostasis and stress response to the control of vital processes such as cell division and signal transduction. To reliably process all the proteins presented to it in the complex cellular environment, the proteasome must combine high promiscuity with exceptional substrate selectivity. Recent structural and biochemical studies have shed new light on the many steps involved in proteasomal substrate processing, including recognition, deubiquitination, and ATP-driven translocation and unfolding. In addition, these studies revealed a complex conformational landscape that ensures proper substrate selection before the proteasome commits to processive degradation. These advances in our understanding of the proteasome's intricate machinery set the stage for future studies on how the proteasome functions as a major regulator of the eukaryotic proteome.


2008 ◽  
Vol 36 (5) ◽  
pp. 781-785 ◽  
Author(s):  
Gemma Marfany ◽  
Rosa Farràs ◽  
Eduardo Salido ◽  
Dimitris P. Xirodimas ◽  
Manuel S. Rodríguez

Proteolysis has traditionally been considered as a radical way to terminate the function of a protein. However, protein destruction also is the starting point for many processes as they can only occur when the way has been cleared for the action of other proteins. Protein destruction can occur virtually in all compartments and organelles of the cell, associated with cell membranes or large protein complexes, it determines subcellular partitioning, association with positive or negative regulators which conditions the action of many critical cellular factors. The third intracellular proteolysis meeting held by the University La Laguna, Canary Islands, Spain, included speakers working with some of the most important proteolytic systems present in higher eukaryotes, such as the UPS (ubiquitin–proteasome system) and autophagy. Owing to the fact that these pathways directly or indirectly regulate many cell functions, this meeting brought together an audience with a wide range of research interests, including genetic, cell biological, biochemical and structural aspects of protein degradation. Some of these topics inspired interesting discussions and a significant number of these are developed in the issues reviewed herein.


Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5938
Author(s):  
Jeongkwan Hong ◽  
Minho Won ◽  
Hyunju Ro

The ligand of Numb protein-X (LNX) family, also known as the PDZRN family, is composed of four discrete RING-type E3 ubiquitin ligases (LNX1, LNX2, LNX3, and LNX4), and LNX5 which may not act as an E3 ubiquitin ligase owing to the lack of the RING domain. As the name implies, LNX1 and LNX2 were initially studied for exerting E3 ubiquitin ligase activity on their substrate Numb protein, whose stability was negatively regulated by LNX1 and LNX2 via the ubiquitin-proteasome pathway. LNX proteins may have versatile molecular, cellular, and developmental functions, considering the fact that besides these proteins, none of the E3 ubiquitin ligases have multiple PDZ (PSD95, DLGA, ZO-1) domains, which are regarded as important protein-interacting modules. Thus far, various proteins have been isolated as LNX-interacting proteins. Evidence from studies performed over the last two decades have suggested that members of the LNX family play various pathophysiological roles primarily by modulating the function of substrate proteins involved in several different intracellular or intercellular signaling cascades. As the binding partners of RING-type E3s, a large number of substrates of LNX proteins undergo degradation through ubiquitin-proteasome system (UPS) dependent or lysosomal pathways, potentially altering key signaling pathways. In this review, we highlight recent and relevant findings on the molecular and cellular functions of the members of the LNX family and discuss the role of the erroneous regulation of these proteins in disease progression.


Author(s):  
Rachel J. Harding ◽  
Yufeng Tong

Many neurodegenerative diseases are characterised by impairment of protein quality control mechanisms in neuronal cells. Ineffective clearance of misfolded proteins by the proteasome, autophagy pathways and exocytosis leads to accumulation of toxic protein oligomers and aggregates in neurons. Toxic protein species affect various cellular functions resulting in the development of a spectrum of different neurodegenerative proteinopathies, including Huntington’s disease (HD). Playing an integral role in proteostasis, dysfunction of the ubiquitylation system in HD is progressive and multi-faceted with numerous biochemical pathways affected, in particular the ubiquitin proteasome system and autophagy routes for protein aggregate degradation. Unravelling the molecular mechanisms involved in HD pathogenesis of proteostasis provides insight in disease progression in HD as well as possible therapeutic avenues. Recent developments of potential therapeutics are discussed in this review.


2020 ◽  
Vol 318 (3) ◽  
pp. C451-C462 ◽  
Author(s):  
Paula Saavedra-García ◽  
Francesca Martini ◽  
Holger W. Auner

Cellular protein homeostasis (proteostasis) depends on the controlled degradation of proteins that are damaged or no longer required by the ubiquitin-proteasome system (UPS). The 26S proteasome is the principal executer of substrate-specific proteolysis in eukaryotic cells and regulates a myriad of cellular functions. Proteasome inhibitors were initially developed as chemical tools to study proteasomal function but rapidly became widely used anticancer drugs that are now used at all stages of treatment for the bone marrow cancer multiple myeloma (MM). Here, we review the mechanisms of action of proteasome inhibitors that underlie their preferential toxicity to MM cells, focusing on endoplasmic reticulum stress, depletion of amino acids, and effects on glucose and lipid metabolism. We also discuss mechanisms of resistance to proteasome inhibition such as autophagy and metabolic rewiring and what lessons we may learn from the success and failure of proteasome inhibition in MM for treating other cancers with proteostasis-targeting drugs.


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