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Nanoscale Feb 2024PROteolysis TArgeting Chimeras (PROTACs), as a recently identified technique in the field of new drug development, provide new concepts for disease treatment and are... (Review)
Review
PROteolysis TArgeting Chimeras (PROTACs), as a recently identified technique in the field of new drug development, provide new concepts for disease treatment and are expected to revolutionize drug discovery. With high specificity and flexibility, PROTACs serve as an innovative research tool to target and degrade disease-relevant proteins that are not currently pharmaceutically vulnerable to eliminating their functions by hijacking the ubiquitin-proteasome system. To date, PROTACs still face the challenges of low solubility, poor permeability, off-target effects, and metabolic instability. The combination of nanotechnology and PROTACs has been explored to enhance the performance of PROTACs regarding overcoming these challenging hurdles. In this review, we summarize the latest advancements in the building-block design of PROTAC prodrug nanoparticles and provide an overview of existing/potential delivery systems and loading approaches for PROTAC drugs. Furthermore, we discuss the current status and prospects of the split-and-mix approach for PROTAC drug optimization. Additionally, the advantages and translational potentials of carrier-free nano-PROTACs and their combinational therapeutic effects are highlighted. This review aims to foster a deeper understanding of this rapidly evolving field and facilitate the progress of nano-PROTACs that will continue to push the boundaries of achieving selectivity and controlled release of PROTAC drugs.
Topics: Proteolysis; Proteolysis Targeting Chimera; Proteasome Endopeptidase Complex; Proteins; Drug Discovery
PubMed: 38305466
DOI: 10.1039/d3nr06059d -
Cell Reports Jul 2023The 26S proteasome comprises 20S catalytic and 19S regulatory complexes. Approximately half of the proteasomes in cells exist as free 20S complexes; however, our...
The 26S proteasome comprises 20S catalytic and 19S regulatory complexes. Approximately half of the proteasomes in cells exist as free 20S complexes; however, our mechanistic understanding of what determines the ratio of 26S to 20S species remains incomplete. Here, we show that glucose starvation uncouples 26S holoenzymes into 20S and 19S subcomplexes. Subcomplex affinity purification and quantitative mass spectrometry reveal that Ecm29 proteasome adaptor and scaffold (ECPAS) mediates this structural remodeling. The loss of ECPAS abrogates 26S dissociation, reducing degradation of 20S proteasome substrates, including puromycylated polypeptides. In silico modeling suggests that ECPAS conformational changes commence the disassembly process. ECPAS is also essential for endoplasmic reticulum stress response and cell survival during glucose starvation. In vivo xenograft model analysis reveals elevated 20S proteasome levels in glucose-deprived tumors. Our results demonstrate that the 20S-19S disassembly is a mechanism adapting global proteolysis to physiological needs and countering proteotoxic stress.
Topics: Humans; Proteasome Endopeptidase Complex; Cytoplasm; Proteolysis; Mass Spectrometry
PubMed: 37384533
DOI: 10.1016/j.celrep.2023.112701 -
Nature Communications Aug 2023M1 macrophages enter a glycolytic state when endogenous nitric oxide (NO) reprograms mitochondrial metabolism by limiting aconitase 2 and pyruvate dehydrogenase (PDH)...
M1 macrophages enter a glycolytic state when endogenous nitric oxide (NO) reprograms mitochondrial metabolism by limiting aconitase 2 and pyruvate dehydrogenase (PDH) activity. Here, we provide evidence that NO targets the PDH complex by using lipoate to generate nitroxyl (HNO). PDH E2-associated lipoate is modified in NO-rich macrophages while the PDH E3 enzyme, also known as dihydrolipoamide dehydrogenase (DLD), is irreversibly inhibited. Mechanistically, we show that lipoate facilitates NO-mediated production of HNO, which interacts with thiols forming irreversible modifications including sulfinamide. In addition, we reveal a macrophage signature of proteins with reduction-resistant modifications, including in DLD, and identify potential HNO targets. Consistently, DLD enzyme is modified in an HNO-dependent manner at Cys and Cys, and molecular modeling and mutagenesis show these modifications impair the formation of DLD homodimers. In conclusion, our work demonstrates that HNO is produced physiologically. Moreover, the production of HNO is dependent on the lipoate-rich PDH complex facilitating irreversible modifications that are critical to NO-dependent metabolic rewiring.
Topics: Nitrogen Oxides; Nitric Oxide; Macrophages; Pyruvate Dehydrogenase Complex; Oxidoreductases; Pyruvates
PubMed: 37607904
DOI: 10.1038/s41467-023-40738-4 -
Free Radical Biology & Medicine Oct 2023Mitochondrial succinate dehydrogenase (SDH), also known as electron transport chain (ETC) Complex II, is the only enzyme complex engaged in both oxidative... (Review)
Review
Mitochondrial succinate dehydrogenase (SDH), also known as electron transport chain (ETC) Complex II, is the only enzyme complex engaged in both oxidative phosphorylation and the tricarboxylic acid (TCA) cycle. SDH has received increasing attention due to its crucial role in regulating mitochondrial metabolism and human health. Despite having the fewest subunits among the four ETC complexes, functional SDH is formed via a sequential and well-coordinated assembly of subunits. Along with the discovery of subunit-specific assembly factors, the dynamic involvement of the SDH assembly process in a broad range of diseases has been revealed. Recently, we reported that perturbation of SDH assembly in different tissues leads to interesting and distinct pathophysiological changes in mice, indicating a need to understand the intricate SDH assembly process in human health and diseases. Thus, in this review, we summarize recent findings on SDH pathogenesis with respect to disease and a focus on SDH assembly.
Topics: Humans; Animals; Mice; Succinate Dehydrogenase; Citric Acid Cycle; Mitochondria; Oxidative Phosphorylation; Multienzyme Complexes
PubMed: 37490987
DOI: 10.1016/j.freeradbiomed.2023.07.023 -
Current Opinion in Structural Biology Oct 2023The final two steps of tryptophan biosynthesis are catalyzed by the enzyme tryptophan synthase (TS), composed of alpha (αTS) and beta (βTS) subunits. Recently,... (Review)
Review
The final two steps of tryptophan biosynthesis are catalyzed by the enzyme tryptophan synthase (TS), composed of alpha (αTS) and beta (βTS) subunits. Recently, experimental and computational methods have mapped "allosteric networks" that connect the αTS and βTS active sites. In αTS, allosteric networks change across the catalytic cycle, which might help drive the conformational changes associated with its function. Directed evolution studies to increase catalytic function and expand the substrate profile of stand-alone βTS have also revealed the importance of αTS in modulating the conformational changes in βTS. These studies also serve as a foundation for the development of TS inhibitors, which can find utility against Mycobacterium tuberculosis and other bacterial pathogens.
Topics: Tryptophan Synthase; Models, Molecular; Catalysis; Allosteric Regulation
PubMed: 37467527
DOI: 10.1016/j.sbi.2023.102657 -
Antioxidants & Redox Signaling Oct 2023Dihydrolipoamide dehydrogenase (DLDH) is a flavin-dependent disulfide oxidoreductase. The active form of DLDH is a stable homodimer, and its deficiencies have been... (Review)
Review
Dihydrolipoamide dehydrogenase (DLDH) is a flavin-dependent disulfide oxidoreductase. The active form of DLDH is a stable homodimer, and its deficiencies have been linked to numerous metabolic disorders. A better understanding of redox and nonredox features of DLDH may reveal druggable targets for disease interventions or preventions. In this article, the authors review the different roles of DLDH in selected pathological conditions, including its deficiency in humans, its role in stroke and neuroprotection, skin photoaging, Alzheimer's disease, and DLDH as a nondehydrogenating protein, and construction of genetically modified DLDH animal models for further studying the role of DLDH in specific pathological conditions. DLDH is also vulnerable to oxidative modifications in pathological conditions. Novel animal models need to be constructed using gene knockdown techniques to investigate the redox- and nonredox roles of DLDH in related metabolic diseases. Specific small-molecule DLDH inhibitors need to be discovered. The relationship between modifications of specific amino acid residues in DLDH and given pathological conditions is an interesting area that remains to be comprehensively evaluated. Cell-specific or tissue-specific knockdown of DLDH creating specific pathological conditions will provide more insights into the mechanisms, whereby DLDH may have therapeutic values under a variety of pathological conditions. 39, 794-806.
Topics: Animals; Humans; Dihydrolipoamide Dehydrogenase; Stroke; Oxidation-Reduction
PubMed: 37276180
DOI: 10.1089/ars.2022.0181 -
Chemical Society Reviews Apr 2024Targeted protein degradation (TPD) has been established as a viable alternative to attenuate the function of a specific protein of interest in both biological and... (Review)
Review
Targeted protein degradation (TPD) has been established as a viable alternative to attenuate the function of a specific protein of interest in both biological and clinical contexts. The unique TPD mode-of-action has allowed previously undruggable proteins to become feasible targets, expanding the landscape of "druggable" properties and "privileged" target proteins. As TPD continues to evolve, a range of innovative strategies, which do not depend on recruiting E3 ubiquitin ligases as in proteolysis-targeting chimeras (PROTACs), have emerged. Here, we present an overview of direct lysosome- and proteasome-engaging modalities and discuss their perspectives, advantages, and limitations. We outline the chemical composition, biochemical activity, and pharmaceutical characteristics of each degrader. These alternative TPD approaches not only complement the first generation of PROTACs for intracellular protein degradation but also offer unique strategies for targeting pathologic proteins located on the cell membrane and in the extracellular space.
Topics: Proteolysis; Proteasome Endopeptidase Complex; Lysosomes; Cell Membrane; Ubiquitin-Protein Ligases
PubMed: 38369971
DOI: 10.1039/d3cs00344b -
European Journal of Medicinal Chemistry Dec 2023Targeted protein degradation (TPD) has emerged as a promising therapeutic approach with potential advantages over traditional occupancy-based inhibitors in terms of... (Review)
Review
Targeted protein degradation (TPD) has emerged as a promising therapeutic approach with potential advantages over traditional occupancy-based inhibitors in terms of dosing, side effects and targeting "undruggable" proteins. Targeted degraders can theoretically bind any nook or cranny of targeted proteins to drive degradation. This offers convenience versus the small-molecule inhibitors that must function in a well-defined pocket. The degradation process depends mainly on two cell self-destruction mechanisms, namely the ubiquitin-proteasome system and the lysosomal degradation pathway. Various TPD strategies (e.g., proteolytic-targeting chimeras, molecular glues, lysosome-targeting chimeras, and autophagy-targeting chimeras) have been developed. These approaches hold great potential for targeting dysregulated proteins, potentially offering therapeutic benefits. In this article, we systematically review the mechanisms of various TPD strategies, potential applications to drug discovery, and recent advances. We also discuss the benefits and challenges associated with these TPD strategies, aiming to provide insight into the targeting of dysregulated proteins and facilitate their clinical applications.
Topics: Proteolysis; Proteasome Endopeptidase Complex; Autophagy; Drug Discovery; Lysosomes
PubMed: 37778240
DOI: 10.1016/j.ejmech.2023.115839 -
Frontiers in Immunology 2023Mutations in genes coding for proteasome subunits and/or proteasome assembly helpers typically cause recurring autoinflammation referred to as chronic atypical...
Mutations in genes coding for proteasome subunits and/or proteasome assembly helpers typically cause recurring autoinflammation referred to as chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperatures (CANDLE) or proteasome-associated autoinflammatory syndrome (PRAAS). Patients with CANDLE/PRAAS present with mostly chronically elevated type I interferon scores that emerge as a consequence of increased proteotoxic stress by mechanisms that are not fully understood. Here, we report on five unrelated patients with CANDLE/PRAAS carrying novel inherited proteasome missense and/or nonsense variants. Four patients were compound heterozygous for novel pathogenic variants in the known CANDLE/PRAAS associated genes, and , whereas one patient showed additive loss-of-function mutations in . Variants in two previously not associated proteasome genes, and , were found in a patient who also carried the founder mutation, p.T75M. All newly identified mutations substantially impact the steady-state expression of the affected proteasome subunits and/or their incorporation into mature 26S proteasomes. Our observations expand the spectrum of PRAAS-associated genetic variants and improve a molecular diagnosis and genetic counseling of patients with sterile autoinflammation.
Topics: Humans; Proteasome Endopeptidase Complex; Syndrome; Cytoplasm; Dermatitis
PubMed: 37600812
DOI: 10.3389/fimmu.2023.1190104 -
Journal of Experimental & Clinical... Sep 2023Tumors have evolved in various mechanisms to evade the immune system, hindering the antitumor immune response and facilitating tumor progression. Immunotherapy has... (Review)
Review
Tumors have evolved in various mechanisms to evade the immune system, hindering the antitumor immune response and facilitating tumor progression. Immunotherapy has become a potential treatment strategy specific to different cancer types by utilizing multifarious molecular mechanisms to enhance the immune response against tumors. Among these mechanisms, the ubiquitin-proteasome system (UPS) is a significant non-lysosomal pathway specific to protein degradation, regulated by deubiquitinating enzymes (DUBs) that counterbalance ubiquitin signaling. Ubiquitin-specific proteases (USPs), the largest DUB family with the strongest variety, play critical roles in modulating immune cell function, regulating immune response, and participating in antigen processing and presentation during tumor progression. According to recent studies, the expressions of some USP family members in tumor cells are involved in tumor immune escape and immune microenvironment. This review explores the potential of targeting USPs as a new approach for cancer immunotherapy, highlighting recent basic and preclinical studies investigating the applications of USP inhibitors. By providing insights into the structure and function of USPs in cancer immunity, this review aims at assisting in developing new therapeutic approaches for enhancing the immunotherapy efficacy.
Topics: Humans; Immunotherapy; Cytoplasm; Proteasome Endopeptidase Complex; Ubiquitin; Ubiquitin-Specific Proteases; Neoplasms
PubMed: 37658402
DOI: 10.1186/s13046-023-02805-y