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European Journal of Medicinal Chemistry Jul 2021Proteasomes contribute to maintaining protein homeostasis and their inhibition is beneficial in certain types of cancer and in autoimmune diseases. However, the...
Proteasomes contribute to maintaining protein homeostasis and their inhibition is beneficial in certain types of cancer and in autoimmune diseases. However, the inhibition of the proteasomes in healthy cells leads to unwanted side-effects and significant effort has been made to identify inhibitors specific for the immunoproteasome, especially to treat diseases which manifest increased levels and activity of this proteasome isoform. Here, we report our efforts to discover fragment-sized inhibitors of the human immunoproteasome. The screening of an in-house library of structurally diverse fragments resulted in the identification of benzo[d]oxazole-2(3H)-thiones, benzo[d]thiazole-2(3H)-thiones, benzo[d]imidazole-2(3H)-thiones, and 1-methylbenzo[d]imidazole-2(3H)-thiones (with a general term benzoXazole-2(3H)-thiones) as inhibitors of the chymotrypsin-like (β5i) subunit of the immunoproteasome. A subsequent structure-activity relationship study provided us with an insight regarding growing vectors. Binding to the β5i subunit was shown and selectivity against the β5 subunit of the constitutive proteasome was determined. Thorough characterization of these compounds suggested that they inhibit the immunoproteasome by forming a disulfide bond with the Cys48 available specifically in the β5i active site. To obtain fragments with biologically more tractable covalent interactions, we performed a warhead scan, which yielded benzoXazole-2-carbonitriles as promising starting points for the development of selective immunoproteasome inhibitors with non-peptidic scaffolds.
Topics: Drug Evaluation, Preclinical; Humans; Inhibitory Concentration 50; Oxazoles; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Protein Subunits; Structure-Activity Relationship; Thiazoles; Thiones
PubMed: 33894528
DOI: 10.1016/j.ejmech.2021.113455 -
Cellular and Molecular Life Sciences :... Sep 2014Melatonin has been widely studied for its role in photoperiodism in seasonal breeders; it is also a potent antioxidant. Ubiquitin, a protein also widespread in living... (Review)
Review
Melatonin has been widely studied for its role in photoperiodism in seasonal breeders; it is also a potent antioxidant. Ubiquitin, a protein also widespread in living cells, contributes to many cellular events, although the most well known is that of tagging proteins for destruction by the proteasome. Herein, we suggest a model in which melatonin interacts with the ubiquitin-proteasome system to regulate a variety of seemingly unrelated processes. Ubiquitin, for example, is a major regulator of central activity of thyroid hormone type 2 deiodinase; the subsequent regulation of T3 may be central to the melatonin-induced changes in seasonal reproduction and seasonal changes in metabolism. Both melatonin and ubiquitin also have important roles in protecting cells from oxidative stress. We discuss the interaction of melatonin and the ubiquitin-proteasome system in oxidative stress through regulation of the ubiquitin-activating enzyme, E1. Previous reports have shown that glutathiolation of this enzyme protects proteins from unnecessary degradation. In addition, evidence is discussed concerning the interaction of ubiquitin and melatonin in activation of the transcription factor NF-κB as well as modulating cellular levels of numerous signal transducing factors including the tumor suppressor, p53. Some of the actions of melatonin on the regulatory particle of the proteasome appear to be related to its inhibition of the calcium-dependent calmodulin kinase II, an enzyme which reportedly copurifies with proteasomes. Many of the actions of melatonin on signal transduction are similar to those of a proteasome inhibitor. While these actions of melatonin could be explained by a direct inhibitory action on the catalytic core particle of the proteasome, this has not been experimentally verified. If our hypothesis of melatonin as a general inhibitor of the ubiquitin-proteasome system is confirmed, it is predicted that more examples of this interaction will be demonstrated in a variety of tissues in which ubiquitin and melatonin co-exist. Furthermore, the hypothesis of melatonin as an inhibitor of the ubiquitin-proteasome system will be a very useful model for clinical testing of melatonin.
Topics: Circadian Rhythm; Melatonin; Models, Biological; Oxidative Stress; Proteasome Endopeptidase Complex; Signal Transduction; Ubiquitin
PubMed: 24920061
DOI: 10.1007/s00018-014-1659-3 -
European Journal of Medicinal Chemistry Nov 2020Ubiquitin-proteasome system, autophagy-lysosome pathway and N-end rule pathway are crucial protein quality control mechanisms in human body. Hijacking these endogenous... (Review)
Review
Ubiquitin-proteasome system, autophagy-lysosome pathway and N-end rule pathway are crucial protein quality control mechanisms in human body. Hijacking these endogenous protein degrading measures by chimera degraders could be a revolutionary strategy for the discovery of small-molecule drugs. As the most advanced chimera degraders, PROTACs have demonstrated the potential by delivering two drug candidates into clinical trials. The development of chimera degraders exploiting these three pathways are reviewed, a focus is given on the chemical structures and their influences on biological effects from a viewpoint of medicinal chemistry.
Topics: Drug Discovery; Humans; Proteasome Endopeptidase Complex; Proteolysis; Ubiquitin
PubMed: 32890974
DOI: 10.1016/j.ejmech.2020.112494 -
The International Journal of... Oct 2016There is growing appreciation for the fundamental role of structural dynamics in the function of macromolecules. In particular, the 26S proteasome, responsible for... (Review)
Review
There is growing appreciation for the fundamental role of structural dynamics in the function of macromolecules. In particular, the 26S proteasome, responsible for selective protein degradation in an ATP dependent manner, exhibits dynamic conformational changes that enable substrate processing. Recent cryo-electron microscopy (cryo-EM) work has revealed the conformational dynamics of the 26S proteasome and established the function of the different conformational states. Technological advances such as direct electron detectors and image processing algorithms allowed resolving the structure of the proteasome at atomic resolution. Here we will review those studies and discuss their contribution to our understanding of proteasome function.
Topics: Animals; Humans; Proteasome Endopeptidase Complex
PubMed: 27498189
DOI: 10.1016/j.biocel.2016.08.008 -
Biomolecules Aug 2022Proteasomes comprise a family of proteasomal complexes essential for maintaining protein homeostasis. Accordingly, proteasomes represent promising therapeutic targets in... (Review)
Review
Proteasomes comprise a family of proteasomal complexes essential for maintaining protein homeostasis. Accordingly, proteasomes represent promising therapeutic targets in multiple human diseases. Several proteasome inhibitors are approved for treating hematological cancers. However, their side effects impede their efficacy and broader therapeutic applications. Therefore, understanding the biology of the different proteasome complexes present in the cell is crucial for developing tailor-made inhibitors against specific proteasome complexes. Here, we will discuss the structure, biology, and function of the alternative Proteasome Activator 200 (PA200), also known as PSME4, and summarize the current evidence for its dysregulation in different human diseases. We hereby aim to stimulate research on this enigmatic proteasome regulator that has the potential to serve as a therapeutic target in cancer.
Topics: Cytoplasm; Humans; Nuclear Proteins; Proteasome Endopeptidase Complex; Proteasome Inhibitors
PubMed: 36009043
DOI: 10.3390/biom12081150 -
Immunology and Cell Biology Oct 2016The immunoproteasome is a proteasome variant that is found only in jawed vertebrates. It is responsible for degrading intracellular proteins to generate a major source... (Review)
Review
The immunoproteasome is a proteasome variant that is found only in jawed vertebrates. It is responsible for degrading intracellular proteins to generate a major source of peptides with substantial major histocompatibility complex I binding affinity. The immunoproteasome also has roles in T-cell survival, differentiation and proliferation in various pathological conditions. In humans, any alteration in the expression, assembly or function of the immunoproteasome can lead to cancer, autoimmune disorders or inflammatory diseases. Although the roles of the immunoproteasome in cancer and neurodegenerative disorders have been extensively studied, its significance in other disease conditions has only recently become known. Therefore, there is renewed interest in the development of drugs, vaccines and biomarkers that target the immunoproteasome. The current review highlights the involvement of this complex in disease pathology in addition to the advances made in immunoproteasome research.
Topics: Animals; Disease; Humans; Models, Biological; Mutation; Proteasome Endopeptidase Complex
PubMed: 27192937
DOI: 10.1038/icb.2016.50 -
The New Phytologist Aug 2017Contents 958 I. 958 II. 959 III. 960 IV. 962 V. 962 962 References 963 SUMMARY: Proteases can either digest target proteins or perform the so-called 'limited... (Review)
Review
Contents 958 I. 958 II. 959 III. 960 IV. 962 V. 962 962 References 963 SUMMARY: Proteases can either digest target proteins or perform the so-called 'limited proteolysis' by cleaving polypeptide chains at specific site(s). Autophagy and the ubiquitin-proteasome system (UPS) are two main mechanisms carrying out digestive proteolysis. While the net outcome of digestive proteolysis is the loss of function of protein substrates, limited proteolysis can additionally lead to gain or switch of function. Recent evidence of crosstalk between autophagy, UPS and limited proteolysis indicates that these pathways are parts of the same proteolytic nexus. Here, we focus on three emerging themes within this area: limited proteolysis as a mechanism modulating autophagy; interplay between autophagy and UPS, including autophagic degradation of proteasomes (proteophagy); and specificity of protein degradation during bulk autophagy.
Topics: Autophagy; Evolution, Molecular; Models, Biological; Proteasome Endopeptidase Complex; Proteolysis; Ubiquitin
PubMed: 28574164
DOI: 10.1111/nph.14627 -
Nature Immunology Sep 2018The basic principle of adaptive immunity is to strictly discriminate between self and non-self, and a central challenge to overcome is the enormous variety of pathogens... (Review)
Review
The basic principle of adaptive immunity is to strictly discriminate between self and non-self, and a central challenge to overcome is the enormous variety of pathogens that might be encountered. In cell-mediated immunity, immunological discernment takes place at a molecular or cellular level. Central to both mechanisms of discernment is the generation of antigenic peptides associated with MHC class I molecules, which is achieved by a proteolytic complex called the proteasome. To adequately accomplish the discrimination between self and non-self that is essential for adaptive immunity and self-tolerance, two proteasome subtypes have evolved via gene duplication: the immunoproteasome and the thymoproteasome. In this Review, we describe various aspects of these immunity-dedicated proteasomes, from their discovery to recent findings.
Topics: Adaptive Immunity; Animals; Autoantigens; Autoimmune Diseases; Evolution, Molecular; Gene Duplication; Histocompatibility Antigens Class I; Humans; Peptides; Proteasome Endopeptidase Complex; Proteolysis; Self Tolerance; Thymus Gland
PubMed: 30104634
DOI: 10.1038/s41590-018-0186-z -
Cardiovascular Research Feb 2020In patients with pulmonary hypertension, right ventricular hypertrophy (RVH) is a detrimental condition that ultimately results in right heart failure and death. The...
AIMS
In patients with pulmonary hypertension, right ventricular hypertrophy (RVH) is a detrimental condition that ultimately results in right heart failure and death. The ubiquitin proteasome system has been identified as a major protein degradation system to regulate cardiac remodelling in the left heart. Its role in right heart hypertrophy, however, is still ambiguous.
METHODS AND RESULTS
RVH was induced in mice by pulmonary artery banding (PAB). Both, expression and activity of the proteasome was found to be up-regulated in the hypertrophied right ventricle (RV) compared to healthy controls. Catalytic inhibition of the proteasome by the two proteasome inhibitors Bortezomib (BTZ) and ONX-0912 partially improved RVH both in preventive and therapeutic applications. Native gel analysis revealed that specifically the 26S proteasome complexes were activated in experimental RVH. Increased assembly of 26S proteasomes was accompanied by elevated expression of Rpn6, a rate-limiting subunit of 26S proteasome assembly, in hypertrophied cardiomyocytes of the right heart. Intriguingly, patients with RVH also showed increased expression of Rpn6 in hypertrophied cardiomyocytes of the RV as identified by immunohistochemical staining.
CONCLUSION
Our data demonstrate that alterations in expression and activity of proteasomal subunits play a critical role in the development of RVH. Moreover, this study provides an improved understanding on the selective activation of the 26S proteasome in RVH that might be driven by the rate-limiting subunit Rpn6. In RVH, Rpn6 therefore represents a more specific target to interfere with proteasome function than the commonly used catalytic proteasome inhibitors.
Topics: Animals; Disease Models, Animal; Heart Ventricles; Humans; Hypertrophy, Right Ventricular; Inflammation Mediators; Mice; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Signal Transduction; Ubiquitination; Ventricular Function, Right; Ventricular Remodeling
PubMed: 31020333
DOI: 10.1093/cvr/cvz103 -
STAR Protocols Dec 2023Proteasomes are heterogeneous in forms and functions, but how the equilibrium among the 20S, 26S, and 30S proteasomes is achieved and altered is elusive. Here, we...
Proteasomes are heterogeneous in forms and functions, but how the equilibrium among the 20S, 26S, and 30S proteasomes is achieved and altered is elusive. Here, we present a protocol for purifying and characterizing proteasome species. We describe steps for generating stable cell lines; affinity purifying the proteasome species; and characterizing them through native PAGE, activity assay, size-exclusion chromatography, and mass spectrometry. These standardized methods may contribute to biochemical studies of cellular proteasomes under both physiological and pathological conditions. For complete details on the use and execution of this protocol, please refer to Choi et al. (2023)..
Topics: Animals; Proteasome Endopeptidase Complex; Cytoplasm; Mass Spectrometry; Chromatography, Gel; Native Polyacrylamide Gel Electrophoresis; Mammals
PubMed: 37999974
DOI: 10.1016/j.xpro.2023.102748