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At least 19 recordsLinked to original sources
PubMed2024

Super Enhanced Purification of Denatured-Refolded Ubiquitinated Proteins by ThUBD Revealed Ubiquitinome Dysfunction in Liver Fibrosis.

Ubiquitination is crucial for maintaining protein homeostasis and plays a vital role in diverse biological processes. Ubiquitinome profiling and quantification are of great scientific significance. Artificial ubiquitin-binding domains (UBDs) have been widely employed to capture ubiquitinated proteins. The success of this enrichment relies on recognizing native spatial structures of ubiquitin and ubiquitin chains by UBDs under native conditions. However, the use of native lysis conditions presents significant challenges, including insufficient protein extraction, heightened activity of deubiquitinating enzymes and proteasomes in removing the ubiquitin signal, and purification of a substantial number of contaminant proteins, all of which undermine the robustness and reproducibility of ubiquitinomics. In this study, we introduced a novel approach that combines denatured-refolded ubiquitinated sample preparation (DRUSP) with a tandem hybrid UBD for ubiquitinomic analysis. The samples were effectively extracted using strongly denatured buffers and subsequently refolded using filters. DRUSP yielded a significantly stronger ubiquitin signal, nearly three times greater than that of the Control method. Then, eight types of ubiquitin chains were quickly and accurately restored; therefore, they were recognized and enriched by tandem hybrid UBD with high efficiency and no biases. Compared with the Control method, DRUSP showed extremely high efficiency in enriching ubiquitinated proteins, improving overall ubiquitin signal enrichment by approximately 10-fold. Moreover, when combined with ubiquitin chain-specific UBDs, DRUSP had also been proven to be a versatile approach. This new method significantly enhanced the stability and reproducibility of ubiquitinomics research. Finally, DRUSP was successfully applied to deep ubiquitinome profiling of early mouse liver fibrosis with increased accuracy, revealing novel insights for liver fibrosis research.

Animals↗
PubMed2025

Ubiquitination of transcription factors in cancer: unveiling therapeutic potential.

Transcription factors, pivotal in gene expression regulation, are essential in cancer progression. Their function is meticulously regulated by post-translational modifications, including ubiquitination. This process, which marks proteins for degradation, can either enhance or inhibit the function of transcription factors, contingent on the context. In cancers, dysregulated ubiquitination of transcription factors contributes to the hallmark of uncontrolled growth and survival of tumors. For example, tumor suppressors such as p53 might be degraded prematurely due to abnormal ubiquitination, causing genomic instability. On the other hand, oncogenic transcription factors may gain stability via ubiquitination, thus facilitating tumorigenesis. Targeting the ubiquitin-proteasome system (UPS) therefore could be a viable therapeutic approach in cancer. Emerging treatments aim to block the ubiquitination of oncogenic transcription factors or to stabilize tumor suppressors. This review underscores the critical impact of transcription factor-altered ubiquitination on cancer progression. Additionally, it outlines innovative therapeutic approaches that involve inhibitors or drugs directed at specific ubiquitin E3 ligases and deubiquitinases (DUBs) that regulate transcription factor activity.

Humans↗
PubMed2026

Molecular mechanism of HUWE1-HAPSTR1-USP7-mediated ubiquitin chain amplification on nuclear proteins.

Rapid protein turnover is essential for cellular stress adaptation. HUWE1 (HECT, UBA, and WWE domain containing 1), a large HECT-type E3 ligase, regulates many short-lived stress-responsive proteins, yet the mechanisms underlying its substrate selectivity remain unclear. Here, we reveal that HUWE1 functions as a ubiquitin chain amplifier that captures pre-ubiquitinated substrates and amplifies the degradation signal by assembling long ubiquitin chains containing K11-K48 branch points, a process regulated by its partners HUWE1-associated protein stress response 1 (HAPSTR1) and USP7 (ubiquitin-specific-processing protease 7). Structural and biochemical analyses show that HAPSTR1 engages HUWE1's ubiquitin-binding motifs to drive nuclear import and modulate substrate recruitment. A cryo-EM structure of the HUWE1-USP7 complex reveals a bidirectional regulatory mechanism: HUWE1 activates USP7's catalytic activity, while USP7 modulates HUWE1 conformational states. Global proteomic analyses demonstrate that this axis drives extensive remodeling of the short-lived nuclear proteome. These findings establish the HUWE1-HAPSTR1-USP7 complex as a key ubiquitin code modifier, providing a molecular rationale for HUWE1 dysregulation in neurodevelopmental disorders and cancer.

Ubiquitin-Specific Peptidase 7↗
PubMed2026

Ubiquitination-Androgen Receptor Coupling in Prostate Cancer Therapeutics.

Prostate cancer is one of the most frequently diagnosed malignancies in men and a leading cause of cancer-related mortality worldwide. The androgen receptor (AR) remains the principal driver of prostate cancer progression and castration-resistant prostate cancer (CRPC), with its stability, localization, and transcriptional activity being tightly regulated by the ubiquitin-proteasome system (UPS). E3 ubiquitin ligases and deubiquitinases (DUBs) critically govern AR turnover and signalling output, thereby influencing tumour growth, therapeutic resistance, and disease progression. Emerging evidence further highlights a complex interplay between ubiquitination, DNA damage response (DDR) pathways, and ADP-ribosylation (ADPr) signalling, collectively shaping genomic stability and treatment responsiveness in prostate cancer. This review is organized into four major themes: (i) ubiquitin-mediated regulation of AR signalling, (ii) ubiquitination and DNA damage response in AR-driven prostate cancer, (iii) crosstalk between ubiquitination, ADPr, and AR-associated signalling pathways, and (iv) therapeutic strategies targeting the UPS and AR axis. This study also discusses recent advances in targeted protein degradation, modulation of E3 ligases, inhibition of deubiquitinases, and PARP-based therapeutic approaches. These emerging insights into the interconnected regulation of ubiquitination, AR signalling, DDR pathways, and ADP-ribosylation may facilitate the development of next-generation therapeutic approaches for advanced prostate cancer.

ADP-ribosylation (ADPr)↗
PubMed2023

RNF4 and USP7 cooperate in ubiquitin-regulated steps of DNA replication.

DNA replication requires precise regulation achieved through post-translational modifications, including ubiquitination and SUMOylation. These modifications are linked by the SUMO-targeted E3 ubiquitin ligases (STUbLs). Ring finger protein 4 (RNF4), one of only two mammalian STUbLs, participates in double-strand break repair and resolving DNA-protein cross-links. However, its role in DNA replication has been poorly understood. Using CRISPR/Cas9 genetic screens, we discovered an unexpected dependency of RNF4 mutants on ubiquitin specific peptidase 7 (USP7) for survival in TP53-null retinal pigment epithelial cells. TP53-/-/RNF4-/-/USP7-/- triple knockout (TKO) cells displayed defects in DNA replication that cause genomic instability. These defects were exacerbated by the proteasome inhibitor bortezomib, which limited the nuclear ubiquitin pool. A shortage of free ubiquitin suppressed the ataxia telangiectasia and Rad3-related (ATR)-mediated checkpoint response, leading to increased cell death. In conclusion, RNF4 and USP7 work cooperatively to sustain a functional level of nuclear ubiquitin to maintain the integrity of the genome.

Animals↗
PubMed2002

RAD6-dependent DNA repair is linked to modification of PCNA by ubiquitin and SUMO.

The RAD6 pathway is central to post-replicative DNA repair in eukaryotic cells; however, the machinery and its regulation remain poorly understood. Two principal elements of this pathway are the ubiquitin-conjugating enzymes RAD6 and the MMS2-UBC13 heterodimer, which are recruited to chromatin by the RING-finger proteins RAD18 and RAD5, respectively. Here we show that UBC9, a small ubiquitin-related modifier (SUMO)-conjugating enzyme, is also affiliated with this pathway and that proliferating cell nuclear antigen (PCNA) -- a DNA-polymerase sliding clamp involved in DNA synthesis and repair -- is a substrate. PCNA is mono-ubiquitinated through RAD6 and RAD18, modified by lysine-63-linked multi-ubiquitination--which additionally requires MMS2, UBC13 and RAD5--and is conjugated to SUMO by UBC9. All three modifications affect the same lysine residue of PCNA, suggesting that they label PCNA for alternative functions. We demonstrate that these modifications differentially affect resistance to DNA damage, and that damage-induced PCNA ubiquitination is elementary for DNA repair and occurs at the same conserved residue in yeast and humans.

Cell Cycle↗
PubMed2024

The prognostic significance of ubiquitination-related genes in multiple myeloma by bioinformatics analysis.

BACKGROUND: Immunoregulatory drugs regulate the ubiquitin-proteasome system, which is the main treatment for multiple myeloma (MM) at present. In this study, bioinformatics analysis was used to construct the risk model and evaluate the prognostic value of ubiquitination-related genes in MM. METHODS AND RESULTS: The data on ubiquitination-related genes and MM samples were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The consistent cluster analysis and ESTIMATE algorithm were used to create distinct clusters. The MM prognostic risk model was constructed through single-factor and multiple-factor analysis. The ROC curve was plotted to compare the survival difference between high- and low-risk groups. The nomogram was used to validate the predictive capability of the risk model. A total of 87 ubiquitination-related genes were obtained, with 47 genes showing high expression in the MM group. According to the consistent cluster analysis, 4 clusters were determined. The immune infiltration, survival, and prognosis differed significantly among the 4 clusters. The tumor purity was higher in clusters 1 and 3 than in clusters 2 and 4, while the immune score and stromal score were lower in clusters 1 and 3. The proportion of B cells memory, plasma cells, and T cells CD4 naïve was the lowest in cluster 4. The model genes KLHL24, HERC6, USP3, TNIP1, and CISH were highly expressed in the high-risk group. AICAr and BMS.754,807 exhibited higher drug sensitivity in the low-risk group, whereas Bleomycin showed higher drug sensitivity in the high-risk group. The nomogram of the risk model demonstrated good efficacy in predicting the survival of MM patients using TCGA and GEO datasets. CONCLUSIONS: The risk model constructed by ubiquitination-related genes can be effectively used to predict the prognosis of MM patients. KLHL24, HERC6, USP3, TNIP1, and CISH genes in MM warrant further investigation as therapeutic targets and to combat drug resistance.

Humans↗
PubMed1977

Induction of human granulocyte differentiation in vitro by ubiquitin and thymopoietin.

Human bone marrow cells were separated according to density by centrifugation on Ficoll-Hypaque gradients and then according to size by velocity sedimentation. This procedure resulted in fractions enriched for immature granulocytes, mature granulocytes, and lymphocytes. Cells in these fractions were analyzed for their expression of certain surface and functional differentiation markers and for their ability to respond to thymopoietin and ubiquitin with the expression of additional differentiation markers. A higher percentage of band form and segmented granulocytes than of more immature granulocytes expressed complement receptors on their surfaces. Thymopoietin and ubiquitin induced a significant percentage of the cells in the immature granulocyte fraction to express this marker. These data suggested that the complement receptor may be viewed as a differentiation marker on human granulocytes, the expression of which can be induced in vitro by thymopoietin and ubiquitin. Furthermore, fractions containing predominantly band form granulocytes were induced by ubiquitin (but not thymopoietin) to develop the capacity to respond to chemotactic agents, and cell fractions containing predominantly myelocytes and metamyelocytes were induced by thymopoietin and ubiquitin to develop the capacity to phagocytose latex particles. These findings indicated that thymopoietin and ubiquitin, two agents known to induce a number of stages of human and mouse lymphocyte differentiation, are also capable of inducing some stages of human granulocyte differentiation in vitro.

Binding Sites, Antibody↗
PubMed2026

Mass spectrometry-based mapping of the ubiquitin chaperone code.

Maintenance of proteome integrity is essential for cellular homeostasis and organismal health. This integrity depends on proteostasis, a coordinated network of protein quality control systems that regulate protein folding, stabilization, and degradation. Molecular chaperones, together with proteolytic pathways such as the ubiquitin-proteasome system (UPS) and the autophagy-lysosomal pathway, prevent the accumulation of misfolded and aggregation-prone proteins. Perturbations, including genetic mutations, environmental stress, and aging challenge protein folding fidelity, leading to proteotoxic stress and contributing to the pathogenesis of neurodegenerative disorders. Among the chaperone machinery, the HSP70 and HSP90 families play central roles in maintaining protein conformational homeostasis and directing damaged or misfolded substrates toward refolding or degradation pathways. Recent studies show that chaperone activity is dynamically regulated by diverse post-translational modifications (PTMs), including phosphorylation, acetylation, and ubiquitination, collectively termed the "chaperone code." These modifications modulate chaperone-client interactions, enzymatic activity, localization, and coordination with protein degradation systems. Mass spectrometry (MS)-based proteomics has emerged as a powerful approach for mapping ubiquitination sites and quantifying ubiquitin signaling dynamics. This chapter outlines experimental and computational strategies for MS-based analysis of the ubiquitin chaperone code, including di-glycine peptide enrichment, site identification, quantitative analysis, and validation.

Humans↗
PubMed2026

Phosphorylation and ubiquitination coordinate homeostasis of a tomato transporter responsible for fruit sugar accumulation.

Sugar transport mediated by different transporters is essential for maintaining sugar homeostasis in plants. Here, we report that phosphorylation and ubiquitination coordinate the homeostasis of a tomato (Solanum lycopersicum) sugar transporter SlSWEET16, revealing a new aspect of plant sugar homeostasis. SlSWEET16 is localized to plasma membrane and functions as a mono- and disaccharide transporter. SlSWEET16 mediates cellular sugar efflux, and CRISPR/Cas9-mediated knockout of SlSWEET16 leads to increased fruit sugar accumulation. Strikingly, the C-terminus of SlSWEET16 is subjected to both phosphorylation and ubiquitination. Two protein kinases including SlSnRK2.3 and SlSnRK2.4 associate with the C-terminus of SlSWEET16, resulting into an increase in the stability of SlSWEET16. Meanwhile, the C-terminus of SlSWEET16 also interacts with an E3 ubiquitin ligase SlTT3.1L2, which decreases the stability of SlSWEET16. SlSnRK2.3 and SlSnRK2.4 inhibit fruit sugar accumulation, whereas SlTT3.1L2 promotes it. Mutations of phosphorylated or ubiquitinated residues in SlSWEET16's C-terminus further corroborate the contribution of phosphorylation and ubiquitination to the stability of SlSWEET16 and fruit sugar accumulation. Our results reveal a multiple-protein regulatory module that integrates different post-translational modifications to control transporter-mediated fruit sugar accumulation.

Solanum lycopersicum↗
PubMed2025

Parkin Induces Ubiquitination and Large Extracellular Vesicle Release of HMGB1 to Activate Antitumor Immunity.

UNLABELLED: Parkin (PRKN) is a mitochondria-associated E3 ubiquitin ligase that mediates mitophagy and organelle quality control. More recently, PRKN has been implicated in stimulating antitumor immunity and reprogramming the tumor immune microenvironment. In this study, we showed that PRKN ubiquitinates the alarmin molecule, high-mobility group box-1 (HMGB1) on Lys146 (K146) using predominantly K48 linkages. By molecular modeling, the in-between-ring domain of PRKN (Gln326-Leu358) made extensive contacts with the amino-terminus A-box of HMGB1 (Met1-Ser42), forming a mitochondria-associated PRKN-HMGB1 complex that juxtaposes K146 to ubiquitin active site residues Gly76 and Arg74. Instead of proteasomal degradation, PRKN ubiquitination of K146 enabled the loading of HMGB1 but not HMGB1 K146A mutant, onto autophagy- and mitochondria-derived large extracellular vesicles (LEV). In turn, released PRKN-HMGB1-LEV stimulated a potent IFN and cytokine response in recipient cells, expanding CD8+ T-cell subsets with effector (CD69+/KLRG1+), self-renewal (TCF1+/PD-1+), and cytotoxic (KLRG1+/GrzB+) properties. Conditional expression of PRKN induced HMGB1 release, activated intratumoral CD8+ T cells, and suppressed syngeneic tumor growth in vivo in a response that was abolished by HMGB1 silencing. These data identify that PRKN-LEV-regulated release of HMGB1 reprograms antitumor immunity via stimulation of IFN signaling and expansion of specialized CD8+ T-cell subsets. SIGNIFICANCE: Parkin ubiquitinates the alarmin molecule HMGB1 to enable its regulated release in large extracellular vesicles that activate interferon signaling, expand specialized CD8+ T-cell subsets, and promote antitumor immunity.

HMGB1 Protein↗
PubMed2004

SUMO and ubiquitin in the nucleus: different functions, similar mechanisms?

The small ubiquitin-related modifier SUMO posttranslationally modifies many proteins with roles in diverse processes including regulation of transcription, chromatin structure, and DNA repair. Similar to nonproteolytic roles of ubiquitin, SUMO modification regulates protein localization and activity. Some proteins can be modified by SUMO and ubiquitin, but with distinct functional consequences. It is possible that the effects of ubiquitination and SUMOylation are both largely due to binding of proteins bearing specific interaction domains. Both modifications are reversible, and in some cases dynamic cycles of modification may be required for activity. Studies of SUMO and ubiquitin in the nucleus are yielding new insights into regulation of gene expression, genome maintenance, and signal transduction.

Amino Acid Sequence↗
PubMed2025

Modulation of the tumor microenvironment by the ubiquitin-proteasome system in colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide, with the tumor microenvironment (TME) playing a pivotal role in its progression and therapeutic resistance. The ubiquitin-proteasome system (UPS), a central regulator of intracellular protein degradation, is increasingly recognized for its involvement in cancer pathogenesis, though its specific role in modulating the CRC TME remains to be fully elucidated. This review aims to systematically summarize current evidence on how the UPS influences the immunosuppressive network within the CRC TME and to evaluate its potential as a therapeutic target. METHODS: We conducted a comprehensive literature search in PubMed, Web of Science, and Scopus databases for original research articles and reviews published between January 2010 and August 2025, using keywords including "ubiquitin-proteasome system," "colorectal cancer," "tumor microenvironment,""immune escape,"and "targeted therapy." Studies were selected based on their relevance to UPS-mediated regulatory mechanisms in CRC TME remodeling, immune cell function, and treatment response. RESULTS: Our analysis of preclinical and clinical evidence reveals that the UPS critically regulates immune evasion in CRC through multiple mechanisms: (1) USP14 stabilizes indoleamine 2,3-dioxygenase 1 (IDO1), enhancing tryptophan catabolism and kynurenine accumulation, which suppresses T-cell activity; (2) E3 ligases including SPOP, C-Cbl, KLHL22, and FBW7 modulate PD-L1/PD-1 protein stability via ubiquitination, thereby influencing immune checkpoint signaling; and (3) ZFP91 facilitates K63-linked ubiquitination of PP2Ac, impairing mTORC1-mediated glycolysis in T cells and reinforcing regulatory T-cell immunosuppression. Additionally, the UPS intersects with key oncogenic pathways such as Wnt/β-catenin, NF-κB, and p53, further shaping the immunosuppressive landscape of CRC. CONCLUSIONS: Targeting the UPS represents a promising strategy to reverse immunosuppression and overcome therapy resistance in CRC. The primary advantage of this approach lies in its ability to simultaneously disrupt multiple immunosuppressive pathways within the TME, offering a potential solution to the limitations of single-target therapies. Current approaches include proteasome inhibitors, E3 ligase modulators, and deubiquitinating enzyme inhibitors, with combination regimens-such as UPS inhibitors with immune checkpoint blockade-showing synergistic efficacy in preclinical models. Future efforts should focus on enhancing the selectivity of UPS-targeting agents, minimizing off-target effects, and integrating genomic profiling to guide personalized treatment. While current evidence strongly supports the therapeutic potential of UPS targeting, its establishment as a reliable alternative therapy in the clinic will depend on overcoming these challenges and validating efficacy in human trials. This review underscores the UPS as a central regulator of the CRC TME and provides a rational basis for novel therapeutic development.

Humans↗
PubMed2025

The RNA helicase DDX17 enhances androgen receptor stability by interacting with the E3 ubiquitin ligase SPOP in prostate cancer.

BACKGROUND: Prostate cancer (PCa) is a common malignancy in men, closely associated with androgen receptor (AR) signaling, and often diagnosed with elevated prostate-specific antigen (PSA). While androgen deprivation therapy (ADT) is effective, resistance develops due to reactivation of AR signaling, driving disease progression. We aimed to explore the role of DDX17 in the progression of PCa through its interaction with SPOP. We hypothesized that DDX17 can stabilize the AR by inhibiting SPOP-mediated ubiquitination, thereby maintaining AR signaling which supports tumor growth and survival. METHODS: We collected gene expression data and clinical information from PCa patients from The Cancer Genome Atlas and Gene Expression Omnibus databases. Messenger RNA (mRNA) and protein levels were quantified using quantitative real-time polymerase chain reaction (PCR) and western blotting, respectively. Cell viability and invasion capabilities were assessed using cell counting kit-8 (CCK-8) and transwell invasion assays. The interactions between DDX17 and SPOP were examined through coimmunoprecipitation assays. RESULTS: DDX17 exhibited high expression in both PCa tissues and cells. Silencing DDX17 led to reduced proliferation and invasion of PCa cells. Mechanistic investigations revealed that DDX17 directly interacted with SPOP, sustaining AR stability by preventing AR ubiquitination. These findings suggest a role of DDX17 in promoting the progression of PCa by binding and blocking SPOP ubiquitination of AR. CONCLUSIONS: This study elucidated a novel mechanism through which the RNA helicase DDX17 can promote PCa progression through its interaction with SPOP, thereby enhancing AR stability by inhibiting AR ubiquitination.

DDX17↗
PubMed2026

Disruption of the ubiquitin-mediated proteolysis pathway: a study of seed aging in Saposhnikovia divaricata caused by UBC1 gene family suppression.

BACKGROUND: Saposhnikovia divaricata (Turcz.) Schischk. is a perennial herb whose seed aging during storage significantly reduces germination rates, limiting industrial-scale production. Reactive oxygen species (ROS)-induced oxidative damage is a key driver of seed aging, but the underlying mechanisms in Saposhnikovia divaricata remain unclear. RESULTS: Suppression of the UBC1 gene family reduces the activity of ubiquitin-conjugating enzymes, leading to dysfunction of the ubiquitin-mediated proteolysis pathway, which in turn decreases protein degradation efficiency and causes the accumulation of damaged proteins. Transcriptome analysis revealed predominant downregulation of genes crucial for seed physiological maintenance. By the fourth year of storage, germination dropped sharply to 30.67%, accompanied by embryo cavitation. Downregulation of ribosome pathway genes hindered ribosome assembly and protein synthesis, while suppression of endoplasmic reticulum protein processing genes led to unfolded/misfolded protein accumulation and intensified cellular stress, accelerating aging. Proteomic analysis showed increased total differential and antioxidant-related proteins. ROS content fluctuated with storage time: peroxyl radicals peaked in year two (5.68 RFU/mg), whereas hydroxyl radicals and hydrogen peroxide were highest in year four (0.0655 pg/mL and 0.0946 pg/mL, respectively), with significant differences across periods. Elevated membrane-related proteins, increased electrical conductivity, and malondialdehyde content (maximum 54.30 nmol/g at year four) confirmed oxidative membrane damage. ROS-induced stress promotes protein misfolding, and reduced UBC1 expression is associated with impaired clearance of misfolded proteins by the ubiquitin-mediated proteolysis pathway. CONCLUSIONS: This study provides the first integrated transcriptomic and proteomic insight into UBC1 deficiency-mediated seed aging in Saposhnikovia divaricata. The findings enhance molecular understanding of seed aging and offer new directions for improving seed storage and viability.

Ubiquitin-Conjugating Enzymes↗
PubMed2026

Quercetin, a flavonoid, suppresses viral proliferation by interfering with the ubiquitin transfer from E1 to E2 enzymes.

Quercetin is recognized for diverse pharmacological activities. However, the mechanism underlying its broad-antiviral effects has not been elucidated. Herein, we identified quercetin as a potent inhibitor of both double-stranded DNA virus Bombyx mori nucleopolyhedrovirus (BmNPV) and single-stranded RNA virus porcine reproductive and respiratory syndrome virus (PRRSV). Surface plasmon resonance (SPR) revealed that quercetin targets host ubiquitin-activating enzyme 1 (Uba1) homologs. Uba1 knockdown reduced viral proliferation and enhanced the antiviral effect of quercetin, whereas Uba1 overexpression functioned oppositely. Quercetin bound Uba1 homologs with high affinity. Notably, mutation of two binding residues, Q977 and G978, significantly disrupted the binding between BmUba1 and quercetin, and abolished quercetin's antiviral activity. Quercetin obstructed the transfer of ubiquitin from Uba1 to the E2 enzyme Ubc6, impairing the ubiquitination process. Similarly, quercetin inhibited PRRSV proliferation via targeting Uba1 in mammals. These findings elucidate the molecular mechanism underlying the pharmacological effects of quercetin, providing a theoretical basis for the development of novel antiviral agents against both DNA and RNA viruses.

Quercetin↗
PubMed2026

Virome-wide ubiquitin ligase discovery reveals diverse mechanisms of immune evasion.

Viruses are intracellular parasites that reprogram the host proteome to promote replication and evade immune recognition. We applied a virome-wide library of ~10,000 open reading frames to discover viral ubiquitin ligases, mapping their mechanisms of degradation and host substrates using targeted CRISPR screens and proteomics. These viral effectors could be classified as canonical ligases that mimic host E3s, hijackers that redirect host E3s, and noncanonical ligases that rewire cullin-RING ligase machinery. These diverse strategies of virus-mediated degradation converged on immune-related substrates, including JAK1 and CUL1β-TrCP, underscoring immune evasion as a major driver of viral ubiquitin ligase evolution. Our findings elucidate viral strategies for exploiting the ubiquitin-proteasome system with potential for therapeutic targeting.

Humans↗
PubMed2026

Ubiquitin ligase HcPUB30 targets HcWRKY1 to regulate monoterpenoids synthesis in Hedychium coronarium.

Hedychium coronarium, a perennial herb belonging to the genus Hedychium Koenig within the family Zingiberaceae, is renowned for its pleasant fragrance. The volatile compounds of flowers are primarily terpenoids, which are catalyzed by terpenoid synthase (TPS). Earlier studies have shown that HcWRKY1 transcription factor can bind to the promoter of HcTPS1, regulating the metabolism of terpenoids. To further investigate the upstream molecular mechanisms that regulate the release of volatile compounds in Hedychium, we focused on a crucial U-box type of E3 ubiquitin ligase involved in regulating transcription factors. This study utilized genomic data to identify HcPUB gene family. In combination with transcriptome data, seven candidate HcPUB genes were identified and cloned with subsequent functional analysis. Yeast two-hybrid assay demonstrated that HcPUB30 was the sole interactor of HcWRKY1 among the seven HcPUB candidates. In vivo and in vitro ubiquitination assays demonstrated that HcPUB30 ubiquitinates and promotes the degradation of HcWRKY1 via the 26S proteasome pathway. Multi-alignment analysis revealed that HcPUB30 possesses a conserved U-box domain and ARM motifs, which are implicated in plant growth and development. Subcellular localization indicated that HcPUB30 is localized in both the nucleus and cytoplasm. Quantitative real-time PCR analysis revealed that HcPUB30 exhibited the highest expression in petal tissues, and its expression peaked during floral senescence stage. Virus-induced gene silencing of HcPUB30 in Hedychium petals resulted in a significant decrease in monoterpenoid content, accompanied by a significant reduction in the relative expression levels of HcWRKY1 and HcTPS1. These findings indicate that HcPUB30 participates in the regulation of monoterpenoid biosynthesis by mediating HcWRKY1 in Hedychium petals.

Plant Proteins↗