Exploring the Ubiquitin-Proteasome System (UPS) through PROTAC Technology (original) (raw)
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To overcome the lack of specificity of cancer therapeutics and thus create a more potent and effective treatment, we developed a novel chimeric protein, IL2-Smurf2. Here, we describe the production of this chimeric IL2-Smurf2 protein and its variants, with inactive or over-active killing components. Using Western blots, we demonstrated the chimeric protein’s ability to specifically enter target cells alone. After entering the cells, the protein showed biological activity, causing cell death that was not seen with an inactive variant, and that was shown to be apoptotic. The chimeric protein also proved to be active as an E3 ligase, as demonstrated by testing total ubiquitination levels along with targeted ubiquitination for degradation. Finally, we tested IL2-Smurf2 and its variants in an in vivo mouse model of leukemia and demonstrated its potential as a drug for the targeted treatment of cancer cells. In the course of this work, we established for the first time the feasibility of ...
Protein degradation induced by PROTAC molecules as an emerging drug discovery strategy
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The traditional concept of drug discovery is based on the occupancy-driven pharmacology model. It implies the development of inhibitors occupying binding sites that directly affect protein functions. Therefore, proteins that do not have such binding sites are generally considered as pharmacologically intractable. Furthermore, drugs that act in this way must be administered in dosage regimens that often result in high systemic drug exposures in order to maintain sufficient protein inhibition. Thus, there is a risk of the onset of off-target binding and side effects. The landscape of drug discovery has been markedly changed since proteolysis targeting chimera (PROTAC) molecules emerged twenty years ago as a part of the event-driven pharmacology model. These are bifunctional molecules that harness the ubiquitin-proteasome system, and are composed of a ligand that binds the protein of interest (POI), a ligand that recruits E3 ubiquitin ligase (E3UL) and a linker that connects these two parts. Pharmacologically, PROTACs bring POI and E3UL into close proximity, which triggers the formation of a functional ternary complex POI–PROTAC–E3UL. This event drives polyubiquitination and subsequent POI degradation by the 26S proteasome. The development and exceptional properties of PROTAC molecules that brought them to clinical studies will be discussed in this paper.
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Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 2012
Background: Synthetic probes that mimic natural substrates can enable the detection of enzymatic activities in a cellular environment. One area where such activity-based probes have been applied is the ubiquitinproteasome pathway, which is emerging as an important therapeutic target. A family of reagents has been developed that specifically label deubiquitylating enzymes (DUBs) and facilitate characterization of their inhibitors. Scope of review: Here we focus on the application of probes for intracellular DUBs, a group of specific proteases involved in the ubiquitin proteasome system. In particular, the functional characterization of the active subunits of this family of proteases that specifically recognize ubiquitin and ubiquitin-like proteins will be discussed. In addition we present the potential and design of activity-based probes targeting kinases and phosphatases to study phosphorylation. Major conclusions: Synthetic molecular probes have increased our understanding of the functional role of DUBs in living cells. In addition to the detection of enzymatic activities of known members, activity-based probes have contributed to a number of functional assignments of previously uncharacterized enzymes. This method enables cellular validation of the specificity of small molecule DUB inhibitors. General significance: Molecular probes combined with mass spectrometry-based proteomics and cellular assays represent a powerful approach for discovery and functional validation, a concept that can be expanded to other enzyme classes. This addresses a need for more informative cell-based assays that are required to accelerate the drug development process. This article is part of a Special Issue entitled: Ubiquitin Drug Discovery and Diagnostics. -like protein; UCH-L1, Ubiquitin carboxyl terminal hydrolase isozyme L1; UCH-L3, Ubiquitin carboxyl terminal hydrolase isozyme L3; UCH-L5, Ubiquitin carboxyl terminal hydrolase isozyme L5; USP7, Ubiquitin specific processing protease 7
Ubiquitin–proteasome system and the role of its inhibitors in cancer therapy
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Despite all the other cells that have the potential to prevent cancer development and metastasis through tumour suppressor proteins, cancer cells can upregulate the ubiquitin–proteasome system (UPS) by which they can degrade tumour suppressor proteins and avoid apoptosis. This system plays an extensive role in cell regulation organized in two steps. Each step has an important role in controlling cancer. This demonstrates the importance of understanding UPS inhibitors and improving these inhibitors to foster a new hope in cancer therapy. UPS inhibitors, as less invasive chemotherapy drugs, are increasingly used to alleviate symptoms of various cancers in malignant states. Despite their success in reducing the development of cancer with the lowest side effects, thus far, an appropriate inhibitor that can effectively inactivate this system with the least drug resistance has not yet been fully investigated. A fundamental understanding of the system is necessary to fully elucidate its ro...
Quantitative Chemical Proteomic Profiling of Ubiquitin Specific Proteases in Intact Cancer Cells
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Deubiquitinating enzymes play an important role in a plethora of therapeutically relevant processes and are emerging as pioneering drug targets. Herein, we present a novel probe, Ubiquitin Specific Protease (USP) inhibitor, alongside an alkyne-tagged activity-based probe analogue. Activity-based proteome profiling identified 12 USPs, including USP4, USP16, and USP33, as inhibitor targets using submicromolar probe concentrations. This represents the first intact cell activitybased profiling of deubiquitinating enzymes. Further analysis demonstrated functional inhibition of USP33 and identified a synergistic relationship in combination with ATR inhibition, consistent with USP4 inhibition.
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The ubiquitin proteasome system (UPS) governs the non-lysosomal degradation of oxidized, damaged, or misfolded proteins in eukaryotic cells. This process is tightly regulated through the activation and transfer of polyubiquitin chains to target proteins which are then recognized and degraded by the 26S proteasome complex. The role of UPS is crucial in regulating protein levels through degradation to maintain fundamental cellular processes such as growth, division, signal transduction, and stress response. Dysregulation of the UPS, resulting in loss of ability to maintain protein quality through proteolysis, is closely related to the development of various malignancies and tumorigenesis. Here, we provide a comprehensive general overview on the regulation and roles of UPS and discuss functional links of dysregulated UPS in human malignancies. Inhibitors developed against components of the UPS, which include U.S. Food and Drug Administration FDA-approved and those currently undergoing ...