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Journal of Experimental Botany Aug 2023The constant battle of survival between pathogens and host plants has played a crucial role in shaping the course of their co-evolution. However, the major determinants... (Review)
Review
The constant battle of survival between pathogens and host plants has played a crucial role in shaping the course of their co-evolution. However, the major determinants of the outcome of this ongoing arms race are the effectors secreted by pathogens into host cells. These effectors perturb the defense responses of plants to promote successful infection. In recent years, extensive research in the area of effector biology has reported an increase in the repertoire of pathogenic effectors that mimic or target the conserved ubiquitin-proteasome pathway. The role of the ubiquitin-mediated degradation pathway is well known to be indispensable for various aspects of a plant's life, and thus targeting or mimicking it seems to be a smart strategy adopted by pathogens. Therefore, this review summarizes recent findings on how some pathogenic effectors mimic or act as one of the components of the ubiquitin-proteasome machinery while others directly target the plant's ubiquitin-proteasome system.
Topics: Proteasome Endopeptidase Complex; Ubiquitination; Plants; Ubiquitin-Protein Ligases; Ubiquitin; Plant Diseases; Plant Immunity
PubMed: 37226440
DOI: 10.1093/jxb/erad191 -
Nature Communications Nov 2023Targeted proteasomal and autophagic protein degradation, often employing bifunctional modalities, is a new paradigm for modulation of protein function. In an attempt to...
Targeted proteasomal and autophagic protein degradation, often employing bifunctional modalities, is a new paradigm for modulation of protein function. In an attempt to explore protein degradation by means of autophagy we combine arylidene-indolinones reported to bind the autophagy-related LC3B-protein and ligands of the PDEδ lipoprotein chaperone, the BRD2/3/4-bromodomain containing proteins and the BTK- and BLK kinases. Unexpectedly, the resulting bifunctional degraders do not induce protein degradation by means of macroautophagy, but instead direct their targets to the ubiquitin-proteasome system. Target and mechanism identification reveal that the arylidene-indolinones covalently bind DCAF11, a substrate receptor in the CUL4A/B-RBX1-DDB1-DCAF11 E3 ligase. The tempered α, β-unsaturated indolinone electrophiles define a drug-like DCAF11-ligand class that enables exploration of this E3 ligase in chemical biology and medicinal chemistry programs. The arylidene-indolinone scaffold frequently occurs in natural products which raises the question whether E3 ligand classes can be found more widely among natural products and related compounds.
Topics: Oxindoles; Ligands; Cullin Proteins; Ubiquitin-Protein Ligases; Proteolysis; Proteasome Endopeptidase Complex; Biological Products; Ubiquitination
PubMed: 38036533
DOI: 10.1038/s41467-023-43657-6 -
Journal of Medicinal Chemistry Aug 2023Targeted protein degradation (TPD) technologies have catalyzed a paradigm shift in therapeutic strategies and offer innovative avenues for drug design. Hydrophobic tags... (Review)
Review
Targeted protein degradation (TPD) technologies have catalyzed a paradigm shift in therapeutic strategies and offer innovative avenues for drug design. Hydrophobic tags (HyTs) are bifunctional TPD molecules consisting of a ″lipophilic small-molecule tags″ group and a small-molecule ligand for the target protein. Despite the vast potential of HyTs, they have received relatively limited attention as a promising frontier. Leveraging their lower molecular weight and reduced numbers of hydrogen bond donors/acceptors (HBDs/HBAs) in comparison with proteolysis-targeting chimeras (PROTACs), HyTs present a compelling approach for enhancing druglike properties. In this Perspective, we explore the diverse range of HyT structures and their corresponding degradation mechanisms, thereby illuminating their broad applicability in targeting a diverse array of proteins, including previously elusive targets. Moreover, we scrutinize the challenges and opportunities entailed in developing this technology as a viable and fruitful strategy for drug discovery.
Topics: Proteolysis; Proteins; Drug Discovery; Drug Design; Ubiquitination; Ubiquitin-Protein Ligases; Proteasome Endopeptidase Complex
PubMed: 37535706
DOI: 10.1021/acs.jmedchem.3c00736 -
PLoS Biology Sep 2023During aging, proteostasis capacity declines and distinct proteins become unstable and can accumulate as protein aggregates inside and outside of cells. Both in disease...
During aging, proteostasis capacity declines and distinct proteins become unstable and can accumulate as protein aggregates inside and outside of cells. Both in disease and during aging, proteins selectively aggregate in certain tissues and not others. Yet, tissue-specific regulation of cytoplasmic protein aggregation remains poorly understood. Surprisingly, we found that the inhibition of 3 core protein quality control systems, namely chaperones, the proteasome, and macroautophagy, leads to lower levels of age-dependent protein aggregation in Caenorhabditis elegans pharyngeal muscles, but higher levels in body-wall muscles. We describe a novel safety mechanism that selectively targets newly synthesized proteins to suppress their aggregation and associated proteotoxicity. The safety mechanism relies on macroautophagy-independent lysosomal degradation and involves several previously uncharacterized components of the intracellular pathogen response (IPR). We propose that this protective mechanism engages an anti-aggregation machinery targeting aggregating proteins for lysosomal degradation.
Topics: Animals; Caenorhabditis elegans; Protein Aggregates; Aging; Proteasome Endopeptidase Complex; Proteostasis
PubMed: 37708127
DOI: 10.1371/journal.pbio.3002284 -
Journal of Medicinal Chemistry Nov 2023Protein tyrosine phosphatase nonreceptor Type 2 (PTPN2) is an attractive target for cancer immunotherapy. PTPN2 and another subtype of PTP1B are highly similar in...
Protein tyrosine phosphatase nonreceptor Type 2 (PTPN2) is an attractive target for cancer immunotherapy. PTPN2 and another subtype of PTP1B are highly similar in structure, but their biological functions are distinct. Therefore, subtype-selective targeting of PTPN2 remains a challenge for researchers. Herein, the development of small molecular PTPN2 degraders based on a thiadiazolidinone dioxide-naphthalene scaffold and a VHL E3 ligase ligand is described, and the PTPN2/PTP1B subtype-selective degradation is achieved for the first time. The linker structure modifications led to the discovery of the subtype-selective PTPN2 degrader (PTPN2/PTP1B selective index > 60-fold), which also exhibits excellent proteome-wide degradation selectivity. induces PTPN2 degradation in a ubiquitination- and proteasome-dependent manner. It efficiently promotes T cell activation and amplifies IFN-γ-mediated B16F10 cell growth inhibition. This study provides a convenient chemical knockdown tool for PTPN2-related research and a paradigm for subtype-selective PTP degradation through nonspecific substrate-mimicking ligands, demonstrating the therapeutic potential of PTPN2 subtype-selective degradation.
Topics: Protein Tyrosine Phosphatase, Non-Receptor Type 2; Phosphorylation; Ubiquitin-Protein Ligases; Ubiquitination; Proteasome Endopeptidase Complex
PubMed: 37966047
DOI: 10.1021/acs.jmedchem.3c01348 -
ELife Oct 2023Recent work has revealed an increasingly important role for mRNA translation in maintaining proteostasis. Here, we use chemical inhibitors targeting discrete steps of...
Recent work has revealed an increasingly important role for mRNA translation in maintaining proteostasis. Here, we use chemical inhibitors targeting discrete steps of translation to compare how lowering the concentration of all or only translation initiation-dependent proteins rescues from proteotoxic stress. We systematically challenge proteostasis and show that pharmacologically inhibiting translation initiation or elongation elicits a distinct protective profile. Inhibiting elongation protects from heat and proteasome dysfunction independently from HSF-1 but does not protect from age-associated protein aggregation. Conversely, inhibition of initiation protects from heat and age-associated protein aggregation and increases lifespan, dependent on , but does not protect from proteotoxicity caused by proteasome dysfunction. Surprisingly, we find that the ability of the translation initiation machinery to control the concentration of newly synthesized proteins depends on HSF-1. Inhibition of translation initiation in wild-type animals reduces the concentration of newly synthesized proteins but increases it in mutants. Our findings suggest that the HSF-1 pathway is not only a downstream target of translation but also directly cooperates with the translation initiation machinery to control the concentration of newly synthesized proteins to restore proteostasis.
Topics: Animals; Caenorhabditis elegans Proteins; Transcription Factors; Proteostasis; Protein Aggregates; Proteasome Endopeptidase Complex; Caenorhabditis elegans; Heat Shock Transcription Factors
PubMed: 37795690
DOI: 10.7554/eLife.76465 -
Molecular Cell Apr 2024Most eukaryotic proteins are degraded by the 26S proteasome after modification with a polyubiquitin chain. Substrates lacking unstructured segments cannot be degraded...
Most eukaryotic proteins are degraded by the 26S proteasome after modification with a polyubiquitin chain. Substrates lacking unstructured segments cannot be degraded directly and require prior unfolding by the Cdc48 ATPase (p97 or VCP in mammals) in complex with its ubiquitin-binding partner Ufd1-Npl4 (UN). Here, we use purified yeast components to reconstitute Cdc48-dependent degradation of well-folded model substrates by the proteasome. We show that a minimal system consists of the 26S proteasome, the Cdc48-UN ATPase complex, the proteasome cofactor Rad23, and the Cdc48 cofactors Ubx5 and Shp1. Rad23 and Ubx5 stimulate polyubiquitin binding to the 26S proteasome and the Cdc48-UN complex, respectively, allowing these machines to compete for substrates before and after their unfolding. Shp1 stimulates protein unfolding by the Cdc48-UN complex rather than substrate recruitment. Experiments in yeast cells confirm that many proteins undergo bidirectional substrate shuttling between the 26S proteasome and Cdc48 ATPase before being degraded.
Topics: Adenosine Triphosphatases; Cell Cycle Proteins; Polyubiquitin; Proteasome Endopeptidase Complex; Proteolysis; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Ubiquitin; Valosin Containing Protein
PubMed: 38401542
DOI: 10.1016/j.molcel.2024.01.029 -
International Journal of Molecular... Nov 2023Sarcomas are heterogeneous bone and soft tissue cancers representing the second most common tumor type in children and adolescents. Histology and genetic profiling... (Review)
Review
Sarcomas are heterogeneous bone and soft tissue cancers representing the second most common tumor type in children and adolescents. Histology and genetic profiling discovered more than 100 subtypes, which are characterized by peculiar molecular vulnerabilities. However, limited therapeutic options exist beyond standard therapy and clinical benefits from targeted therapies were observed only in a minority of patients with sarcomas. The rarity of these tumors, paucity of actionable mutations, and limitations in the chemical composition of current targeted therapies hindered the use of these approaches in sarcomas. Targeted protein degradation (TPD) is an innovative pharmacological modality to directly alter protein abundance with promising clinical potential in cancer, even for undruggable proteins. TPD is based on the use of small molecules called degraders or proteolysis-targeting chimeras (PROTACs), which trigger ubiquitin-dependent degradation of protein of interest. In this review, we will discuss major features of PROTAC and PROTAC-derived genetic systems for target validation and cancer treatment and focus on the potential of these approaches to overcome major issues connected to targeted therapies in sarcomas, including drug resistance, target specificity, and undruggable targets. A deeper understanding of these strategies might provide new fuel to drive molecular and personalized medicine to sarcomas.
Topics: Adolescent; Child; Humans; Proteolysis; Sarcoma; Soft Tissue Neoplasms; Precision Medicine; Genetic Profile; Neoplasms, Second Primary; Ubiquitin-Protein Ligases; Proteasome Endopeptidase Complex
PubMed: 38003535
DOI: 10.3390/ijms242216346 -
The Journal of Cell Biology Sep 2023Glutathionylation is a posttranslational modification involved in various molecular and cellular processes. However, it remains unknown whether and how glutathionylation...
Glutathionylation is a posttranslational modification involved in various molecular and cellular processes. However, it remains unknown whether and how glutathionylation regulates nervous system development. To identify critical regulators of synapse growth and development, we performed an RNAi screen and found that postsynaptic knockdown of glutathione transferase omega 1 (GstO1) caused significantly more synaptic boutons at the Drosophila neuromuscular junctions. Genetic and biochemical analysis revealed an increased level of glass boat bottom (Gbb), the Drosophila homolog of mammalian bone morphogenetic protein (BMP), in GstO1 mutants. Further experiments showed that GstO1 is a critical regulator of Gbb glutathionylation at cysteines 354 and 420, which promoted its degradation via the proteasome pathway. Moreover, the E3 ligase Ctrip negatively regulated the Gbb protein level by preferentially binding to glutathionylated Gbb. These results unveil a novel regulatory mechanism in which glutathionylation of Gbb facilitates its ubiquitin-mediated degradation. Taken together, our findings shed new light on the crosstalk between glutathionylation and ubiquitination of Gbb in synapse development.
Topics: Animals; Drosophila; Neuromuscular Junction; Proteasome Endopeptidase Complex; Synapses; Drosophila Proteins
PubMed: 37389657
DOI: 10.1083/jcb.202202068 -
Acta Pharmacologica Sinica Dec 20235-Fluorouracil (5-FU) is the first-line treatment for colorectal cancer (CRC) patients, but the development of acquired resistance to 5-FU remains a big challenge....
5-Fluorouracil (5-FU) is the first-line treatment for colorectal cancer (CRC) patients, but the development of acquired resistance to 5-FU remains a big challenge. Deubiquitinases play a key role in the protein degradation pathway, which is involved in cancer development and chemotherapy resistance. In this study, we investigated the effects of targeted inhibition of the proteasomal deubiquitinases USP14 and UCHL5 on the development of CRC and resistance to 5-FU. By analyzing GEO datasets, we found that the mRNA expression levels of USP14 and UCHL5 in CRC tissues were significantly increased, and negatively correlated with the survival of CRC patients. Knockdown of both USP14 and UCHL5 led to increased 5-FU sensitivity in 5-FU-resistant CRC cell lines (RKO-R and HCT-15R), whereas overexpression of USP14 and UCHL5 in 5-FU-sensitive CRC cells decreased 5-FU sensitivity. B-AP15, a specific inhibitor of USP14 and UCHL5, (1-5 μM) dose-dependently inhibited the viability of RKO, RKO-R, HCT-15, and HCT-15R cells. Furthermore, treatment with b-AP15 reduced the malignant phenotype of CRC cells including cell proliferation and migration, and induced cell death in both 5-FU-sensitive and 5-FU-resistant CRC cells by impairing proteasome function and increasing reactive oxygen species (ROS) production. In addition, b-AP15 inhibited the activation of NF-κB pathway, suppressing cell proliferation. In 5-FU-sensitive and 5-FU-resistant CRC xenografts nude mice, administration of b-AP15 (8 mg·kg·d, intraperitoneal injection) effectively suppressed the growth of both types of tumors. These results demonstrate that USP14 and UCHL5 play an important role in the development of CRC and resistance to 5-FU. Targeting USP14 and UCHL5 with b-AP15 may represent a promising therapeutic strategy for the treatment of CRC.
Topics: Animals; Mice; Humans; Proteasome Endopeptidase Complex; Fluorouracil; Mice, Nude; Apoptosis; Cell Line, Tumor; Colorectal Neoplasms; Drug Resistance, Neoplasm; Ubiquitin Thiolesterase
PubMed: 37528233
DOI: 10.1038/s41401-023-01136-0