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Increasing evidence highlights the important role of ubiquitination in cancer. The objective of our study is to establish a reliable marker for predicting clinical outcomes and treatment responses in patients with clear cell renal cell carcinoma (ccRCC) using genes related to ubiquitination (URGs). The URGs subtypes were identified using consensus clustering based on TCGA-KIRC, and a signature containing the prognostic differentially expressed genes of the subtypes was determined using LASSO and Cox regression analysis. To demonstrate the strength of the signature, verification analyses were performed on both E-MTAB-1980 and TCGA-KIRC test datasets. We developed a nomogram to enhance the effectiveness of our predictive tool. Risk genes expression was determined through RT-qPCR. Six genes were combined to create the URGs signature, which had a highly correlated with patient prognosis in patients with ccRCC. A nomogram was developed based on the URGs signature and clinicopathological characteristics. We found that the predictive power was substantially greater than the other individual predictors. Moreover, the study on the immune microenvironment revealed significant variations in the levels of immune cells and the expression of immune checkpoint genes among the groups categorized as high-risk and low-risk. Furthermore, it was found that immunotherapy yielded better outcomes in cohorts with low risk. The URGs signature might serve as a novel and powerful prognosis biomarker and offer a momentous reference for individualized treatment for patients in ccRCC. [ABSTRACT FROM AUTHOR]

Cisplatin-based chemotherapy serves as the standard of care for individuals with advanced stages of gastric cancer. Nevertheless, the emergence of chemoresistance in GC has detrimental impacts on prognosis, yet the underlying mechanisms governing this phenomenon remain elusive. Level of mitophagy and ferroptosis of GC cells were detected by fluorescence, flow cytometry, GSH, MDA, Fe2+ assays, and to explore the specific molecular mechanisms between NPR1 and cisplatin resistance by performing western blot and coimmunoprecipitation (co-IP) assays. These results indicates that NPR1 positively correlated with cisplatin-resistance and played a crucial part in conferring resistance to cisplatin in gastric cancer cells. Mechanistically, NPR1 affected levels of mitophagy and ferroptosis in human cisplatin-resistance GC cells with cisplatin treatment. Specifically, NPR1 inhibited mitophagy-dependent ferroptosis by reducing the ubiquitination-mediated degradation of PARL; moreover, NPR1 promoted PARL stabilization by disrupting the PARL–MARCH8 complex, which ultimately led to the development of chemoresistance in GC cells. Considering our findings, NPR1 appears to play an important role in chemotherapy for GC. NPR1 could potentially be used to overcome chemotherapy resistance. 1. NPR1 is highly expressed in cisplatin-resistant GC cells and promotes the cisplatin resistance. 2. According to IP-MS, NPR1 inhibits mitophagy-dependent ferroptosis through its downstream protein PARL. 3. NPR1 promoted PARL stabilization by disrupting the PARL–MARCH8 complex to inhibit the ubiquitination-mediated degradation of PARL. [ABSTRACT FROM AUTHOR]

Background: Ubiquitination is one of the most prevalent and complex posttranslational modifications of proteins in eukaryotes, playing a critical role in regulating various physiological and pathological processes. Targeting ubiquitination pathways, either through inhibition or activation, holds promise as a novel therapeutic approach for cancer treatment. However, the expression patterns, prognostic significance, and underlying mechanisms of ubiquitination-related genes (URGs) in sarcoma (SARC) remain unclear. Methods: We analyzed URG expression patterns and prognostic implications in TCGA-SARC using public databases, identifying DEGs related to ubiquitination among SARC molecular subtypes. Functional enrichment analysis elucidated their biological significance. Prognostic signatures were developed using LASSO-Cox regression, and a predictive nomogram was constructed. External validation was performed using GEO datasets and clinical tissue samples. The association between URG risk scores and various clinical parameters, immune response, drug sensitivity, and RNA modification regulators was investigated. Integration of data from multiple sources and RT-qPCR confirmed upregulated expression of prognostic URGs in SARC. Single-cell RNA sequencing data analyzed URG distribution across immune cell types. Prediction analysis identified potential target genes of microRNAs and long non-coding RNAs. Results: We identified five valuable genes (CALR, CASP3, BCL10, PSMD7, PSMD10) and constructed a prognostic model, simultaneously identifying two URG-related subtypes in SARC. The UEGs between subtypes in SARC are mainly enriched in pathways such as Cell cycle, focal adhesion, and ECM-receptor interaction. Analysis of URG risk scores reveals that patients with a low-risk score have better prognoses compared to those with high-risk scores. There is a significant correlation between DRG risk score and clinical features, immune therapy response, drug sensitivity, and genes related to pan-RNA epigenetic modifications. High-risk SARC patients were identified as potential beneficiaries of immune checkpoint inhibitor therapy. We established regulatory axes in SARC, including CALR/hsa-miR-29c-3p/LINC00943, CASP3/hsa-miR-143-3p/LINC00944, and MIR503HG. RT-qPCR data further confirmed the upregulation of prognostic URGs in SARC. Finally, we validated the prognostic model's excellent predictive performance in predicting outcomes for SARC patients. Conclusion: We discovered a significant correlation between aberrant expression of URGs and prognosis in SARC patients, identifying a prognostic model related to ubiquitination. This model provides a basis for individualized treatment and immunotherapy decisions for SARC patients. [ABSTRACT FROM AUTHOR]

Background: Sepsis is often accompanied by lactic acidemia and acute lung injury (ALI). Clinical studies have established that high serum lactate levels are associated with increased mortality rates in septic patients. We further observed a significant correlation between the levels of cold-inducible RNA-binding protein (CIRP) in plasma and bronchoalveolar lavage fluid (BALF), as well as lactate levels, and the severity of post-sepsis ALI. The underlying mechanism, however, remains elusive. Methods: C57BL/6 wild type (WT), Casp8−/−, Ripk3−/−, and Zbp1−/− mice were subjected to the cecal ligation and puncture (CLP) sepsis model. In this model, we measured intra-macrophage CIRP lactylation and the subsequent release of CIRP. We also tracked the internalization of extracellular CIRP (eCIRP) in pulmonary vascular endothelial cells (PVECs) and its interaction with Z-DNA binding protein 1 (ZBP1). Furthermore, we monitored changes in ZBP1 levels in PVECs and the consequent activation of cell death pathways. Results: In the current study, we demonstrate that lactate, accumulating during sepsis, promotes the lactylation of CIRP in macrophages, leading to the release of CIRP. Once eCIRP is internalized by PVEC through a Toll-like receptor 4 (TLR4)-mediated endocytosis pathway, it competitively binds to ZBP1 and effectively blocks the interaction between ZBP1 and tripartite motif containing 32 (TRIM32), an E3 ubiquitin ligase targeting ZBP1 for proteasomal degradation. This interference mechanism stabilizes ZBP1, thereby enhancing ZBP1-receptor-interacting protein kinase 3 (RIPK3)-dependent PVEC PANoptosis, a form of cell death involving the simultaneous activation of multiple cell death pathways, thereby exacerbating ALI. Conclusions: These findings unveil a novel pathway by which lactic acidemia promotes macrophage-derived eCIRP release, which, in turn, mediates ZBP1-dependent PVEC PANoptosis in sepsis-induced ALI. This finding offers new insights into the molecular mechanisms driving sepsis-related pulmonary complications and provides potential new therapeutic strategies. [ABSTRACT FROM AUTHOR]

Objective: Chondrosarcoma (CHS) is resistant to conventional chemotherapy and radiotherapy and currently lacks effective treatment options when in advanced stages. Accordingly, this research investigated the mechanism of RNF2/CBX7 in CHS to drive the development of molecularly targeted drugs for CHS. Methods: RNF2 and CBX7 levels were detected in CHS cells and tissues. RNF2 and CBX7 expression was modulated through cell transfection to examine their effects on cell proliferation, apoptosis, migration, and angiogenesis. The correlation between RNF2 and CBX7 levels was determined, and the ubiquitination level of CBX7 was tested. Protein synthesis was blocked in RNF2-knockdown/overexpressing cells with CHX to assess the effect of RNF2 on CBX7 stability. JJ012 cells transfected with LV-sh-RNF2 were subcutaneously injected into nu/nu nude mice to ascertain the action of RNF2 in the growth and metastasis of CHS. Results: RNF2 was highly expressed in CHS cells and tissues. RNF2 knockdown curbed CHS cell proliferation, migration, and angiogenesis while promoting apoptosis. RNF2 knockdown in JJ012 cells upregulated CBX7 protein levels and reduced CBX7 ubiquitination, whilst RNF2 had no effect on CBX7 mRNA expression. CBX7 knockdown partially nullified the repressing effects of RNF2 knockdown on CHS cell proliferation, migration, and angiogenesis, and CBX7 overexpression partially abolished the promotional effects of RNF2 overexpression. LV-sh-RNF2 prominently restricted tumor growth and weight and declined lung metastatic nodules and Ki-67-positive cells in mice. Conclusion: RNF2 fosters CHS progression by elevating CBX7 degradation via the ubiquitination pathway. [ABSTRACT FROM AUTHOR]

Arboviruses, transmitted by medical arthropods, pose a serious health threat worldwide. During viral infection, Post Translational Modifications (PTMs) are present on both host and viral proteins, regulating multiple processes of the viral lifecycle. In this study, a mammalian E3 ubiquitin ligase WWP2 (WW domain containing E3 ubiquitin ligase 2) is identified, which interacts with the NS1 protein of Zika virus (ZIKV) and mediates K63 and K48 ubiquitination of Lys 265 and Lys 284, respectively. WWP2‐mediated NS1 ubiquitination leads to NS1 degradation via the ubiquitin‐proteasome pathway, thereby inhibiting ZIKV infection in mammalian hosts. Simultaneously, it is found Su(dx), a protein highly homologous to host WWP2 in mosquitoes, is capable of ubiquitinating NS1 in mosquito cells. Unexpectedly, ubiquitination of NS1 in mosquitoes does not lead to NS1 degradation; instead, it promotes viral infection in mosquitoes. Correspondingly, the NS1 K265R mutant virus is less infectious to mosquitoes than the wild‐type (WT) virus. The above results suggest that the ubiquitination of the NS1 protein confers different adaptations of ZIKV to hosts and vectors, and more importantly, this explains why NS1 K265‐type strains have become predominantly endemic in nature. This study highlights the potential application in antiviral drug and vaccine development by targeting viral proteins' PTMs. [ABSTRACT FROM AUTHOR]

Breast cancer has become the leading cause of death in women. Membrane associated ring‐CH‐type finger 1 (MARCHF1) is associated with the development of various types of cancer, but the exact role of MARCHF1 in breast cancer remains unclear. In our study, the higher MARCHF1 expression was observed in tumor samples of patients with breast cancer and then the role of MARCHF1 in breast cancer was further evaluated. Overexpression of MARCHF1 contributed to proliferation of cancer cells and inhibition of oxidative stress. Knockdown of MARCHF1 reduced breast cancer cell proliferation, increased mitochondrial dysfunction induced by oxidative stress, eventually aggravating cell death. In vivo, MARCHF1 promoted the tumor growth and oppositely, MARCHF1 silencing suppressed the tumor development. Moreover, MARCHF1 interacted with repressor Element‐1 silencing transcription factor (REST) and facilitated its ubiquitylation and degradation. Subsequently, REST negatively regulated the transcription of mitochondrial transcription factor A (TFAM). The subcutaneous tumor formation assay in nude mice also supported these conclusions. In details, knockdown of MARCHF1 upregulated the protein expression of REST and downregulated the mRNA level of TFAM. On the contrary, MARCHF1 overexpression exhibited opposite effects. Thus, MARCHF1 is conducive to the progression of breast cancer via promoting the ubiquitylation and degradation of RSET and then the transcription of TFAM. Downregulating MARCHF1 could provide a novel direction for treating breast cancer. [ABSTRACT FROM AUTHOR]

Background: Lung cancer constitutes the leading cause of cancer mortality. High levels of endothelin-1 (ET-1), its cognate receptor ETAR and its activating enzyme, the endothelin-converting enzyme-1 (ECE-1), have been reported in several cancer types, including lung cancer. ECE-1 comprises four isoforms, which only differ in their cytoplasmic N-terminus. Protein kinase CK2 phosphorylates the N-terminus of isoform ECE-1c, increasing its stability and leading to enhanced invasiveness in glioblastoma and colorectal cancer cells, which is believed to be mediated by the amino acid residue Lys-6, a conserved putative ubiquitination site neighboring the CK2-phosphorylated residues Ser-18 and Ser-20. Whether Lys-6 is linked to the acquisition of a cancer stem cell (CSC)-like phenotype and aggressiveness in human non–small cell lung cancer (NSCLC) cells has not been studied. Methods: In order to establish the role of Lys-6 in the stability of ECE-1c and its involvement in lung cancer aggressiveness, we mutated this residue to a non-ubiquitinable arginine and constitutively expressed the wild-type (ECE-1cWT) and mutant (ECE-1cK6R) proteins in A549 and H1299 human NSCLC cells by lentiviral transduction. We determined the protein stability of these clones alone or in the presence of the CK2 inhibitor silmitasertib, compared to ECE-1cWT and mock-transduced cells. In addition, the concentration of secreted ET-1 in the growth media was determined by ELISA. Expression of stemness genes were determined by Western blot and RT-qPCR. Chemoresistance to cisplatin was studied by MTS viability assay. Migration and invasion were measured through transwell and Matrigel assays, respectively, and the side-population was determined using flow cytometry. Results: ECE-1cK6R displayed higher stability in NSCLC cells compared to ECE-1cWT-expressing cells, but ET-1 secreted levels showed no difference up to 48 h. Most importantly, ECE-1cK6R promoted expression of the stemness genes c-Myc, Sox-2, Oct-4, CD44 and CD133, which enhance cellular self-renewal capability. Also, the ECE-1cK6R-expressing cells showed higher cisplatin chemoresistance, correlating with an augmented side-population abundance due to the increased expression of the ABCG2 efflux pump. Finally, the ECE-1cK6R-expressing cells showed enhanced invasiveness, which correlated with the regulated expression of known EMT markers. Conclusions: Our findings suggest an important role of ECE-1c in lung cancer. ECE-1c is key in a non-canonical ET-1-independent mechanism which triggers a CSC-like phenotype, leading to enhanced lung cancer aggressiveness. Underlying this mechanism, ECE-1c is stabilized upon phosphorylation by CK2, which is upregulated in many cancers. Thus, phospho-ECE-1c may be considered as a novel prognostic biomarker of recurrence, as well as the CK2 inhibitor silmitasertib as a potential therapy for lung cancer patients. [ABSTRACT FROM AUTHOR]

Peritoneal fibrosis has been linked to hypoxia-inducible factor 1-alpha (HIF-1α) as well as O-linked-N-acetylglucosaminylation (O-GlcNAcylation) in peritoneal dialysis (PD). Genistein, recognized for its HIF-1α inhibitory and antifibrotic effects, presents a potential intervention against peritoneal mesothelial-mesenchymal transition (MMT) as well as fibrosis in PD. This study employed human peritoneal mesothelial cells (HPMCs) together with adenine-induced chronic kidney disease (CKD) rats undergoing peritoneal dialysis to explore Genistein's role in high glucose-induced peritoneal MMT and fibrosis. Our findings reveal that Genistein exerts anti-MMT and anti-fibrotic effects by inhibiting HIF-1α in HPMCs under high glucose conditions. Genistein inhibited O-GlcNAcylation status of HIF-1α through the mTOR/O-GlcNAc transferase (OGT) pathway, promoting its ubiquitination as well as the subsequent proteasomal degradation. In adenine-induced CKD rats undergoing peritoneal dialysis, Genistein suppressed the mTOR/OGT expression and reduced the abundance of O-GlcNAcylation along with HIF-1α in the peritoneum. Additionally, Genistein protected against increased peritoneal thickness, fibrosis, and angiogenesis, while improving peritoneal function. Based on our results, it could be inferred that Genistein might inhibit the abundance of HIF-1α via the mTOR/OGT pathway, thereby ameliorating MMT as well as fibrosis in PD. [ABSTRACT FROM AUTHOR]

Protein aggregation causes a wide range of neurodegenerative diseases. Targeting and removing aggregates, but not the functional protein, is a considerable therapeutic challenge. Here, we describe a therapeutic strategy called "RING-Bait," which employs an aggregating protein sequence combined with an E3 ubiquitin ligase. RING-Bait is recruited into aggregates, whereupon clustering dimerizes the RING domain and activates its E3 function, resulting in the degradation of the aggregate complex. We exemplify this concept by demonstrating the specific degradation of tau aggregates while sparing soluble tau. Unlike immunotherapy, RING-Bait is effective against both seeded and cell-autonomous aggregation. RING-Bait removed tau aggregates seeded from Alzheimer's disease (AD) and progressive supranuclear palsy (PSP) brain extracts and was also effective in primary neurons. We used a brain-penetrant adeno-associated virus (AAV) to treat P301S tau transgenic mice, reducing tau pathology and improving motor function. A RING-Bait strategy could be applied to other neurodegenerative proteinopathies by replacing the Bait sequence to match the target aggregate. [Display omitted] • RING-Bait technology turns aggregate sequences into potent aggregate degraders • RING-Bait degraders remove pre-existing aggregates and prevent new ones from forming • RING-Bait degraders prevent seeded aggregation from human AD and PSP tau aggregates • RING-Bait degraders reduce tau pathology and improve motor function in vivo RING-Bait technology hijacks the process of templated aggregation to recruit ubiquitination machinery and selectively degrade pathogenic tau assemblies without generating a specific binder, thereby reducing tau pathology and improving motor function in vivo. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a widely spread opportunistic pathogen that can infect nearly all warm-blooded vertebrates and cause serious toxoplasmosis in immunosuppressed animals and patients. However, the relationship between the host's innate immune system and effector proteins is poorly understood, particularly with regard to how effectors antagonize cGAS-STING signaling during T. gondii infection. In this study, the ROP5 from the PRU strain of T. gondii was found to promote cGAS-STING-mediated immune responses. Mechanistically, ROP5 interacted with STING through predicted domain 2 and modulated cGAS-STING signaling in a predicted domain 3-dependent manner. Additionally, ROP5 strengthened cGAS-STING signaling by enhancing the K63-linked ubiquitination of STING. Consistently, ROP5 deficient PRU (PRUΔROP5) induced fewer type I IFN-related immune responses and replicated faster than the parental strain in RAW264.7 cells. Taken together, this study provides new insights into the mechanism by which ROP5 regulates T. gondii infection and provides new clues for strategies to prevent and control toxoplasmosis. [ABSTRACT FROM AUTHOR]

Non-small cell lung cancer (NSCLC) remains a disease with a poor prognosis despite the advances in therapies. NSCLC with actionable oncogenic alterations represent a subgroup of diseases for which tyrosine kinase inhibitors (TKIs) have shown relevant and robust impact on prognosis, both in early and advanced stages. While the introduction of powerful TKIs increases the ratio of potentially curable patients, the disease does develop resistance over time through either secondary mutations or bypass activating tracks. Therefore, new treatment strategies are being developed to either overcome this inevitable resistance or to prevent it, and proteolysis targeting chimera agents (PROTACs) are among them. They consist of two linked molecules that bind to a target protein and an E3 ubiquitin ligase that causes ubiquitination and degradation of proteins of interest. In this paper, we review the rationale for PROTAC therapy and the current development of PROTACs for oncogene-addicted lung cancer. Moreover, we critically analyze the strengths and limitations of this promising technique that may help pave the way for future perspectives. [ABSTRACT FROM AUTHOR]

Background: Lung cancer is one of the most frequent cancers and the leading cause of cancer-related deaths worldwide with poor prognosis. A disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4) is crucial in the regulation of the extracellular matrix (ECM), impacting its formation, homeostasis and remodeling, and has been linked to cancer progression. However, the specific involvement of ADAMTS4 in the development of lung cancer remains unclear. Methods: ADAMTS4 expression was identified in human lung cancer samples by immunohistochemical (IHC) staining and the correlation of ADAMTS4 with clinical outcome was determined. The functional impact of ADAMTS4 on malignant phenotypes of lung cancer cells was explored both in vitro and in vivo. The mechanisms underlying ADAMTS4-mediated lung cancer progression were explored by ubiquitination-related assays. Results: Our study revealed a significant upregulation of ADAMTS4 at the protein level in lung cancer tissues compared to para-carcinoma normal tissues. High ADAMTS4 expression inversely correlated with the prognosis of lung cancer patients. Knockdown of ADAMTS4 inhibited the proliferation and migration of lung cancer cells, as well as the tubule formation of HUVECs, while ADAMTS4 overexpression exerted opposite effects. Mechanistically, we found that ADAMTS4 stabilized c-Myc by inhibiting its ubiquitination, thereby promoting the in vitro and in vivo growth of lung cancer cells and inducing HUVECs tubule formation in lung cancer. In addition, our results suggested that ADAMTS4 overexpression activated MAPK signaling pathway. Conclusions: We highlighted the promoting role of ADAMTS4 in lung cancer progression and proposed ADAMTS4 as a promising therapeutic target for lung cancer patients. [ABSTRACT FROM AUTHOR]

CCAAT/enhancer‐binding protein α (C/EBPα), a key myeloid transcription factor, drives myeloid differentiation from blast cells by regulating the expression of granulocyte colony stimulating factor receptor and C/EBPε as required for promoting granulocyte differentiation. Here, we show that serine/threonine‐protein kinase NLK, also known as Nemo‐like kinase, physically associates with C/EBPα and phosphorylates it at multiple sites, including Ser21, Thr226, Thr230 and S234, leading to its ubiquitin‐mediated degradation. Individual phospho‐point mutants of C/EBPα could be phosphorylated by NLK, but a mutant with all phosphorylatable residues replaced by alanine resisted phosphorylation and degradation by NLK, as did the single point mutants. Furthermore, although ectopic expression of NLK enhanced phosphorylation of C/EBPα levels, it markedly inhibited total C/EBPα protein levels. Conversely, NLK depletion inhibited endogenous C/EBPα phosphorylation but enhanced its total protein levels in several acute myeloid leukemia (AML) cell lines and in peripheral blood mononuclear cells isolated from number of AML patient samples. Importantly, NLK depletion in peripheral blood mononuclear cells from primary AML patients not only restored C/EBPα protein levels, but also induced myeloid differentiation, suggesting that NLK could be therapeutically targeted to restore C/EBPα to resolve differentiation arrest in AML. [ABSTRACT FROM AUTHOR]

Cells respond to invading pathogens and danger signals from the environment by adapting gene expression to meet the need for protective effector molecules. While this innate immune response is required for the cell and the organism to recover, excess immune activation may lead to loss of homeostasis, thereby promoting chronic inflammation and cancer progression. The molecular basis of innate immune defence is comprised of factors promoting survival and proliferation, such as cytokines, antimicrobial peptides and anti‐apoptotic proteins. As the molecular mechanisms regulating innate immune responses are conserved through evolution, the fruit fly Drosophila melanogaster serves as a convenient, affordable and ethical model organism to enhance understanding of immune signalling. Fly immunity against bacterial infection is built up by both cellular and humoral responses, where the latter is regulated by the Imd and Toll pathways activating NF‐κB transcription factors Relish, Dorsal and Dif, as well as JNK activation and JAK/STAT signalling. As in mammals, the Drosophila innate immune signalling pathways are characterised by ubiquitination of signalling molecules followed by ubiquitin receptors binding to the ubiquitin chains, as well as by rapid changes in protein levels by ubiquitin‐mediated targeted proteasomal and lysosomal degradation. In this review, we summarise the molecular signalling pathways regulating immune responses to pathogen infection in Drosophila, with a focus on ubiquitin‐dependent control of innate immunity and inflammatory signalling. [ABSTRACT FROM AUTHOR]

SUMMARY E2 ubiquitin‐conjugating enzymes play a crucial role in the ubiquitination process by catalyzing ubiquitin transfer. Although the function of ubiquitin‐protein ligases (E3s) in plants response to diverse abiotic stress by targeting specific substrates has been well studied, the involvement of E2s in environmental responses and their downstream targets are not well understood. In this study, we demonstrated that the E2 ubiquitin‐conjugating enzyme 18 (UBC18) influences the stability of FREE1 to modulate iron deficiency stress. UBC18 affects the ubiquitination of FREE1 and promotes its degradation, and overexpression of UBC18 decreases plants’ sensitivity to iron deficiency by reducing FREE1 level, whereas the ubc18 mutant exhibits sensitivity due to elevated FREE1 accumulation. This study also identified that lysine residues K227, K295, K315, and K540 are required for FREE1 ubiquitination and stability regulation. Mutating these lysine residues in FREE1 resulted in plants’ sensitivity to iron starvation. Taken together, our findings shed light on the mechanism of UBC18 in responding to iron deficiency stress by modulating the abundance of FREE1, and further elucidate the role of ubiquitination sites in FREE1 stability regulation and the plant iron deficiency response. [ABSTRACT FROM AUTHOR]

PROTAC® (proteolysis-targeting chimera) molecules induce proximity between an E3 ligase and protein-of-interest (POI) to target the POI for ubiquitin-mediated degradation. Cooperative E3-PROTAC-POI complexes have potential to achieve neo-substrate selectivity beyond that established by POI binding to the ligand alone. Here, we extend the collection of ubiquitin ligases employable for cooperative ternary complex formation to include the C-degron E3 KLHDC2. Ligands were identified that engage the C-degron binding site in KLHDC2, subjected to structure-based improvement, and linked to JQ1 for BET-family neo-substrate recruitment. Consideration of the exit vector emanating from the ligand engaged in KLHDC2's U-shaped degron-binding pocket enabled generation of SJ46421, which drives formation of a remarkably cooperative, paralog-selective ternary complex with BRD3BD2. Meanwhile, screening pro-drug variants enabled surmounting cell permeability limitations imposed by acidic moieties resembling the KLHDC2-binding C-degron. Selectivity for BRD3 compared to other BET-family members is further manifested in ubiquitylation in vitro, and prodrug version SJ46420-mediated degradation in cells. Selectivity is also achieved for the ubiquitin ligase, overcoming E3 auto-inhibition to engage KLHDC2, but not the related KLHDC1, KLHDC3, or KLHDC10 E3s. In sum, our study establishes neo-substrate-specific targeted protein degradation via KLHDC2, and provides a framework for developing selective PROTAC protein degraders employing C-degron E3 ligases. KLHDC2 is a promising E3 ligase for targeted protein degradation (TPD). In this study, the authors demonstrate that heterobifunctional degraders induce cooperative ternary complexes with KLHDC2 and BRD3. They highlight exit vector, neo-substrate, E3 ligase selectivity, and prodrug choice can effectively leverage C-degron E3s for TPD. [ABSTRACT FROM AUTHOR]

Background: Ubiquitination, a major post-translational modification, significantly impacts tumorigenesis, progression, and prognosis. This study aims to classify colon cancer at the molecular level and create a reliable signature using ubiquitination-related genes (URGs) to assess the immune microenvironment and prognosis. Methods: We employed non-negative matrix factorization to subtype colon cancer based on ubiquitination-related gene (URG) expression patterns. Quantitative scores for 28 immune cell infiltrates and the tumor microenvironment were computed using single-sample gene set enrichment analysis (ssGSEA) and the Estimate algorithm. Subtype feature genes were selected through Lasso logistic regression and SVM-RFE algorithm. The ubiquitination-related signature was constructed using univariate Cox, Lasso, and stepwise regression methods to categorize patients into high and low-risk groups. Validation included log-rank tests, receiver operating characteristic (ROC) analysis, decision curve analysis (DCA), and external dataset validation. Immune therapy response was compared using Tumor Immune Dysfunction and Exclusion (TIDE), Immunophenoscore (IPS), and submap analyses. Clinical variables and risk scores were integrated into an enhanced nomogram. The early diagnostic value of four URGs was confirmed via quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry. The cell proliferation was assessed through colony formation, EdU staining, and xenograft tumorigenesis assays. Results: Prognostic ubiquitination-related genes (URGs) stratified patients into subtypes, revealing differences in survival, immune cell infiltration, and pathological staging. A signature of 6 URGs (ARHGAP4, MID2, SIAH2, TRIM45, UBE2D2, WDR72) was identified from 57 subtype-related genes. The high-risk group exhibited characteristics indicative of enhanced epithelial-mesenchymal transition, immune escape, immunosuppressive myeloid-derived suppressor cells, regulatory T cell infiltration, and lower immunogenicity. In contrast, the low-risk group demonstrated the opposite trend but showed a better response to CTLA4 checkpoint inhibitors. The predictive performance of the nomogram significantly improved with the integration of risk score, stage, and age ARHGAP4 and SIAH2 exhibit promising early diagnostic capabilities. Additionally, WDR72 knockdown significantly inhibited CRC cell proliferation both in vitro and in vivo. Conclusion: Our developed ubiquitination-related signature and genes serve as promising biomarkers for colon cancer prognosis, immune microenvironment, and diagnosis. [ABSTRACT FROM AUTHOR]

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Transcription cofactor vestigial-like 3 (VGLL3), as a master regulator of female-biased autoimmunity, also functions in tumor development, while the underlying mechanisms remain largely elusive. Here, we report that VGLL3 plays an important role in DNA damage response (DDR). VGLL3 can be recruited to damage sites in a PARylation-dependent manner. VGLL3 depletion impairs the accumulation of RNF8 and RAD51 at sites of DNA damage, leading to reduced homologous recombination efficiency and increased cellular sensitivity to chemotherapeutic drugs. Mechanistically, VGLL3 can prevent CtIP from KLHL15-mediated ubiquitination and degradation through competitive binding with KLHL15 and, meanwhile, stabilize MDC1 by limiting TRIP12-MDC1 but promoting USP7-MDC1 associations for optimal RNF8 signaling initiation. Consistently, VGLL3 depletion delays tumor development and sensitizes the xenografts to etoposide treatment. Overall, our results reveal an unexpected role of VGLL3 in DDR, which is distinct from its transcriptional cofactor function and not conserved among VGLL family members. [ABSTRACT FROM AUTHOR]

Small-molecule degraders of disease-driving proteins offer a clinically proven modality with enhanced therapeutic efficacy and potential to tackle previously undrugged targets. Stable and long-lived degrader-mediated ternary complexes drive fast and profound target degradation; however, the mechanisms by which they affect target ubiquitination remain elusive. Here, we show cryo-EM structures of the VHL Cullin 2 RING E3 ligase with the degrader MZ1 directing target protein Brd4BD2 toward UBE2R1-ubiquitin, and Lys456 at optimal positioning for nucleophilic attack. In vitro ubiquitination and mass spectrometry illuminate a patch of favorably ubiquitinable lysines on one face of Brd4BD2, with cellular degradation and ubiquitinomics confirming the importance of Lys456 and nearby Lys368/Lys445, identifying the "ubiquitination zone." Our results demonstrate the proficiency of MZ1 in positioning the substrate for catalysis, the favorability of Brd4BD2 for ubiquitination by UBE2R1, and the flexibility of CRL2 for capturing suboptimal lysines. We propose a model for ubiquitinability of degrader-recruited targets, providing a mechanistic blueprint for further rational drug design. [ABSTRACT FROM AUTHOR]

Background: Endometrial cancer (EC) presents significant clinical challenges due to its heterogeneity and complex pathophysiology. SAMHD1, known for its role as a deoxynucleotide triphosphate triphosphohydrolase, has been implicated in the progression of various cancers, including EC. This study focuses on elucidating the role of SAMHD1 in EC through its impact on TRIM27-mediated PTEN ubiquitination. Results: Utilizing a combination of bioinformatics and cellular biology techniques, we investigated the interactions among SAMHD1, TRIM27, and PTEN. Our findings reveal that SAMHD1 modulates PTEN ubiquitination via TRIM27, impacting key pathways involved in EC pathogenesis. These interactions suggest a critical mechanism by which SAMHD1 could influence tumor behavior and progression in EC. Conclusions: The results from this study underscore the potential of targeting the SAMHD1-TRIM27-PTEN axis as a therapeutic strategy in EC. By providing new insights into the molecular mechanisms underlying EC progression, our research supports the development of novel therapeutic approaches that could contribute to improve treatment strategies for patients with EC. [ABSTRACT FROM AUTHOR]

Summary Marchantia polymorpha, occupying a basal position in the monophyletic assemblage of land plants, displays a notable expansion of plant U‐box (PUB) proteins compared with those in animals. We elucidated the roles of MpPUB9 in regulating salt stress tolerance in M. polymorpha. MpPUB9 expression was rapidly induced by high salinity and dehydration. MpPUB9 possessed an intact U‐box domain in the N‐terminus. MpPUB9‐Citrine localized to punctate structures and was peripherally associated with microsomal membranes. Phenotypic analyses demonstrate that the hyponastic and epinastic thallus growth phenotypes, which were induced by the overexpression and suppression of MpPUB9, may provoke salt stress‐resistant and ‐susceptible phenotypes, respectively. MpPUB9 was also found to directly interact with the exocyst protein MpEXO70.1, leading to its ubiquitination. Under high‐salinity conditions, though the stability of MpPUB9 was dramatically increased, MpEXO70.1 showed slightly faster turnover rates. Transcriptome analyses showed that salt treatment and the overexpression of MpPUB9 co‐upregulated the genes related to the modulation of H2O2 and cell wall organization. Overall, our results suggest that MpPUB9 plays a crucial role in the positive regulation of salt stress tolerance, resulting from its interaction with MpEXO70.1 and modulating turnover of the protein under high‐salt conditions via the coordination of UPS with autophagy. [ABSTRACT FROM AUTHOR]

Ubiquitination is a post-translational modification (PTM), which is critical to maintain cell homeostasis. Ubiquitin-specific protease 24 (USP24) plays roles in various diseases, the mechanisms by which USP24 regulates hepatocellular carcinoma (HCC) remain poorly understood. In this study, USP24 is found to be significantly downregulated in HCC. Knocking down USP24 promotes HCC proliferation and migration, whereas USP24 overexpression inhibits HCC in vitro and in vivo. The endogenous interaction between USP24 and Beclin1 is confirmed. Mechanically, USP24 delays Beclin1 degradation by reducing its K48-linked ubiquitination, the effects of overexpressing USP24 on HCC proliferation can be partially reversed by silencing Beclin1. We find that increased autophagy is accompanied by ferroptosis in USP24 overexpressed HCC cells and USP24 increases the susceptibility of HCC to sorafenib. Collectively, this study highlights the critical role of USP24 in regulating autophagy-dependent ferroptosis by decreasing Beclin1 ubiquitination, suggesting that targeting USP24 may be a strategy for treating HCC. The deubiquitinase USP24 stabilizes Beclin1 by decreasing its K48-linked ubiquitination. The interaction between USP24 and Beclin1 represents a key molecular mechanism that promotes autophagy related ferroptosis in HCC. [ABSTRACT FROM AUTHOR]

The chemical synthesis of histones with homogeneous modifications is a powerful approach for quantitatively deciphering the functional crosstalk between different post‐translational modifications (PTMs). In this study, we developed an expedient site‐specific (poly)ubiquitylation strategy (CAEPL, Cysteine Aminoethylation coupled with Enzymatic Protein Ligation), which integrates the Cys‐aminoethylation reaction with the process of ubiquitin‐activating enzyme UBA1‐assisted native chemical ligation. Using this strategy, we successfully prepared monoubiquitylated and K63‐linked di‐ and tri‐ubiquitylated linker histone H1.0 proteins, which were incorporated into individual chromatosomes. Quantitative biochemical analysis of different RNF168 constructs on H1 ubiquitylated chromatosomes with different ubiquitin chain lengths demonstrated that K63‐linked polyubiquitylated H1.0 could directly stimulate RNF168 ubiquitylation activity by enhancing the affinity between RNF168 and the chromatosome. Subsequent cryo‐EM structural analysis of the RNF168/UbcH5c–Ub/H1.0‐K63‐Ub3 chromatosome complex revealed the potential recruitment orientation between RNF168 UDM1 domain and K63‐linked ubiquitin chain on H1.0. Finally, we explored the impact of H1.0 ubiquitylation on RNF168 activity in the context of asymmetric H1.0–K63‐Ub3 di‐nucleosome substrate, revealing a comparable stimulation effect of both the inter‐ and intra‐nucleosomal crosstalk. Overall, our study highlights the significance of access to structurally defined polyubiquitylated H1.0 by the CAEPL strategy, enabling in‐depth mechanistic investigations of in‐trans PTM crosstalk between linker histone H1.0 and core histone H2A ubiquitylation. [ABSTRACT FROM AUTHOR]

Background: Our previous study found that tumor suppressor nitrogen permease regulator like-2(NPRL2) is frequently downregulated in glioma, leading to malignant growth. However, NPRL2-mediated crosstalk between tumor cells and immune cells remains unclear. Methods: The regulatory effects of NPRL2 on tripartite motif–containing protein 16(TRIM16) dependent ubiquitination degradation of Galectin-3(Gal-3) were explored. The effects of Gal-3 on copper uptake, immunocompetence and cuproptosis were investigated in CD8+T lymphocytes(CD8+T cells). The ability of NPRL2 to protect CD8+T cells from Gal-3 damage was evaluated. Furthermore, the correlations among NPRL2, TRIM16, Gal-3 and CD8+T cell accumulation were analyzed in glioma clinical specimens. Results: NPRL2 increased the TRIM16 expression via inactivation of ERK1/2, which in turn promoted the ubiquitination-mediated degradation of Gal-3 and diminished Gal-3 release from glioma cells. Moreover, Gal-3 accelerated copper uptake and triggered cuproptosis in CD8+T cells, whereas NPRL2 increased CD8+T cell recruitment and prevented impairment of CD8+T cells by Gal-3. Clinical samples revealed that NPRL2 expression was positively associated with TRIM16 expression and negatively correlated with Gal-3, but Gal-3 expression was negatively associated with CD8+T cell accumulation. Conclusion: Glioma-derived NPRL2/TRIM16/Gal-3 axis participates in the regulation of CD8+T cell cuproptosis, which provides a promising strategy to rescue the immune activity of CD8+T cells and reverse immunosuppression in glioma. [ABSTRACT FROM AUTHOR]

Ubiquitination, a multifaceted post-translational modification, regulates protein function, degradation, and gene expression. The pivotal role of ubiquitination in the pathogenesis and progression of cancer, including colorectal, breast, and liver cancer, is well-established. Osteosarcoma, an aggressive bone tumor predominantly affecting adolescents, also exhibits dysregulation of the ubiquitination system, encompassing both ubiquitination and deubiquitination processes. This dysregulation is now recognized as a key driver of osteosarcoma development, progression, and chemoresistance. This review highlights recent progress in elucidating how ubiquitination modulates tumor behavior across signaling pathways. We then focus on the mechanisms by which ubiquitination influences osteosarcoma cell function. Finally, we discuss the potential for targeting the ubiquitin-proteasome system in osteosarcoma therapy. By unraveling the impact of ubiquitination on osteosarcoma cell physiology, we aim to facilitate the development of novel strategies for prognosis, staging, treatment, and overcoming chemoresistance. [ABSTRACT FROM AUTHOR]

Background: Infertility is a global reproductive health burden. Assisted reproductive technologies (ARTs) have been widely used to help patients become pregnant. Few embryos develop to the blastocyst stage with ARTs, leading to relatively low live birth rates. Protein modifications play crucial roles in nearly every aspect of cell biology, including reproductive processes. The aim of this study was to explore the characteristics of protein modifications during embryonic development. Methods: Proteomic data from humans and mice were acquired from the integrated proteome resources (iProX) of ProteomeXchange (PXD024267) and a tandem mass tag (TMT)‐mass spectrometry dataset. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were applied for functional annotation. Protein–protein interactions (PPIs) of the modification‐related genes were revealed by the STRING database. Modified proteins during mouse embryogenesis were visualized through heatmaps of hierarchically clustering using k‐means. Results: We identified modification‐related proteins in human embryo development and characterized them through heatmaps, GO analysis, KEGG analysis, and PPI network analysis. We found that the 4‐cell stage to the 8‐cell stage might be the demarcation period for modification‐related protein expression patterns during embryo development. Using quantitative mass spectrometry, we elucidated the methylation, acetylation, and ubiquitination events that occur during mouse embryogenesis to validate our findings in human embryonic development to some extent. Conclusions: The results of our study suggest that the posttranslational modifications (PTMs) of human preimplantation embryos might exhibit the same trends as those in mice to exert synergistic and fine‐tuned regulatory effects during embryonic development. [ABSTRACT FROM AUTHOR]

Selective autophagy is a protein clearance mechanism mediated by evolutionarily conserved selective autophagy receptors (SARs), which specifically degrades misfolded, misassembled, or metabolically regulated proteins. SARs help the host to suppress viral infections by degrading viral proteins. However, viruses have evolved sophisticated mechanisms to counteract, evade, or co-opt autophagic processes, thereby facilitating viral replication. Therefore, this review aims to summarize the complex mechanisms of SARs involved in viral infections, specifically focusing on how viruses exploit strategies to regulate selective autophagy. We present an updated understanding of the various critical roles of SARs in viral pathogenesis. Furthermore, newly discovered evasion strategies employed by viruses are discussed and the ubiquitination-autophagy-innate immune regulatory axis is proposed to be a crucial pathway to control viral infections. This review highlights the remarkable flexibility and plasticity of SARs in viral infections. [ABSTRACT FROM AUTHOR]

Ubiquitin modification of viral proteins to degrade or regulate their function is one of the strategies of the host to resist viral infection. Here, we report that ubiquitin protein ligase E3C (UBE3C), an E3 ubiquitin ligase, displayed inhibitory effects on EV-A71 replication. UBE3C knockdown resulted in increased viral protein levels and virus titers, whereas overexpression of UBE3C reduced EV-A71 replication. To explore the mechanism by which UBE3C affected EV-A71 infection, we found that the C-terminal of UBE3C bound to 2C protein and facilitated K33/K48-linked ubiquitination degradation of 2C K268. Moreover, UBE3C lost its ability to degrade 2C K268R and had a diminished inhibitory impact against the replication of recombinant EV-A71-FY-2C K268R. In addition, UBE3C also promoted ubiquitination degradation of the 2C protein of CVB3 and CVA16 and inhibited viral replication. Thus, our findings reveal a novel mechanism that UBE3C acts as an enterovirus host restriction factor, including EV-A71, by targeting the 2C protein. [ABSTRACT FROM AUTHOR]

Background: Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract, but the molecular mechanisms underlying IBD are incompletely understood. In this study, we explored the role and regulating mechanism of otubain 2 (OTUB2), a deubiquitinating enzyme, in IBD. Methods: To study the function of OTUB2 in IBD, we generated Otub2–/– mice and treated them with dextran sulfate sodium (DSS) to induce experimental colitis. Bone marrow transplantation was performed to identify the cell populations that were affected by OTUB2 in colitis. The molecular mechanism of OTUB2 in signal transduction was studied by various biochemical methods. Results: OTUB2 was highly expressed in colon‐infiltrating macrophages in both humans with IBD and mice with DSS‐induced experimental colitis. Colitis was significantly aggravated in Otub2–/– mice and bone marrow chimeric mice receiving Otub2–/– bone marrow. OTUB2‐deficiency impaired the production of cytokines and chemokines in macrophages in response to the NOD2 agonist muramyl dipeptide (MDP). Upon MDP stimulation, OTUB2 promoted NOD2 signaling by stabilizing RIPK2. Mechanistically, OTUB2 inhibited the proteasomal degradation of RIPK2 by removing K48‐linked polyubiquitination on RIPK2, which was mediated by the active C51 residue in OTUB2. In mice, OTUB2 ablation abolished the protective effects of MDP administration in colitis. Conclusion: This study identified OTUB2 as a novel regulator of intestinal inflammation. [ABSTRACT FROM AUTHOR]

Background: α-Crystallin B (CRYAB) is a chaperone member of the HSPs family that protects proteins with which it interacts from degradation. This study aims to investigate the effect of CRYAB on the progression of colorectal cancer (CRC) and its underlying mechanism. Methods: CRYAB expression was evaluated in CRC tissues. Cell growth was tested by CCK-8 kit. Lipid reactive oxygen species (ROS) assays, lipid peroxidation assays, glutathione assays were used to assess the degree of cellular lipid peroxidation of CRC cells. The potential signal pathways of CRYAB were analyzed and verified by Western blot (WB) and immunoprecipitation (Co-IP). Results: CRYAB expression was elevated in CRC tissues and exhibited sensitivity and specificity in predicting CRC. Functionally, knockdown of CRYAB induced ferroptosis in CRC cells. Mechanistically, CRYAB binding prevented from β-catenin interacting with TRIM55, leading to an increase in β-catenin protein stability, which desensitized CRC cells to ferroptosis and ultimately accelerated cancer progression. Conclusions: Targeting CRYAB might be a promising strategy to enhance ferroptosis and improve the efficacy of CRC therapy. [ABSTRACT FROM AUTHOR]

Angiomiotin (AMOT) family comprises three members: AMOT, AMOT‐like protein 1 (AMOTL1), and AMOT‐like protein 2 (AMOTL2). AMOTL2 is widely expressed in endothelial cells, epithelial cells, and various cancer cells. Specifically, AMOTL2 predominantly localizes in the cytoplasm and nucleus in human normal cells, whereas associates with cell–cell junctions and actin cytoskeleton in non‐human cells, and locates at cell junctions or within the recycling endosomes in cancer cells. AMOTL2 is implicated in regulation of tube formation, cell polarity, and shape, although the specific impact on tumorigenesis remains to be conclusively determined. It has been shown that AMOTL2 enhances tumor growth and metastasis in pancreatic, breast, and colon cancer, however inhibits cell proliferation and migration in lung, hepatocellular cancer, and glioblastoma. In addition to its role in cell shape and cytoskeletal dynamics through co‐localization with F‐actin, AMOTL2 modulates the transcription of Yes‐associated protein (YAP) by binding to it, thereby affecting its phosphorylation and cellular sequestration. Furthermore, the stability and cellular localization of AMOTL2, influenced by its phosphorylation and ubiquitination mediated by specific proteins, affects its cellular function. Additionally, we observe that AMOTL2 is predominantly downregulated in some tumors, but significantly elevated in colorectal adenocarcinoma (COAD). Moreover, overall analysis, GSEA and ROC curve analysis indicate that AMOTL2 exerts as an oncogenic protein in COAD by modulating Wnt pathway, participating in synthesis of collagen formation, and interacting with extracellular matrix receptor. In addition, AMOTL2 potentially regulates the distribution of immune cells infiltration in COAD. In summary, AMOTL2 probably functions as an oncogene in COAD. Consequently, further in‐depth mechanistic research is required to elucidate the precise roles of AMOTL2 in various cancers. [ABSTRACT FROM AUTHOR]

The liver plays an important role in regulating lipid metabolism in animals. This study investigated the function and mechanism of lncLLM in liver lipid metabolism in hens at the peak of egg production. The effect of lncLLM on intracellular lipid content in LMH cells was evaluated by qPCR, Oil Red O staining, and detection of triglyceride (TG) and cholesterol (TC) content. The interaction between lncLLM and MYH9 was confirmed by RNA purification chromatin fractionation (CHIRP) and RNA immunoprecipitation (RIP) analysis. The results showed that lncLLM increased the intracellular content of TG and TC and promoted the expression of genes related to lipid synthesis. It was further found that lncLLM had a negative regulatory effect on the expression level of MYH9 protein in LMH cells. The intracellular TG and TC content of MYH9 knockdown cells increased, and the expression of genes related to lipid decomposition was significantly reduced. In addition, this study confirmed that the role of lncLLM is at least partly through mediating the ubiquitination of MYH9 protein to accelerate the degradation of MYH9 protein. This discovery provides a new molecular target for improving egg-laying performance in hens and treating fatty liver disease in humans. [ABSTRACT FROM AUTHOR]

FBXO protein family plays an essential role in the ubiquitination process acting as E3 ligases, which may contribute to the progression of cancers. However, the molecular functions of FBXOs in hepatocellular carcinoma (HCC) remain incompletely understood. Here, we investigated the overlapping genes between the FBXOs and differentially expressed genes (DEGs) of HCC identified by utilizing The Cancer Genome Atlas (TCGA) dataset, then, a prognostic model with effective predictive capacity was constructed based on the uni-cox and LASSO regression analyses. To elucidate the underlying mechanism of the FBXO model genes, KEGG analysis was carried out. Drug metabolism-cytochrome P450 and retinol metabolism were revealed as the potential pathway, which Increased the credibility of subsequent drug prediction research. Meanwhile, patients divided by the prognostic model showed a different immune infiltrating status and we also found FBXO model genes may ubiquitinate P53, inducing TP53 more prone to mutations, thereby promoting the occurrence and development of tumors. Consistent with these findings, the result of immunohistochemistry (IHC) validated an elevated expression of these model genes in HCC tissues than in the adjacent tissues. The primary aim of this investigation is to formulate a prognostic model while exploring the underlying mechanisms associated with FBXO genes in HCC. These findings offer initial research perspectives on the involvement of FBXO genes in HCC and contribute to the discovery of dependable biomarkers for the management, prognostication, and early detection of HCC in patients. [ABSTRACT FROM AUTHOR]

Purpose: Bromodomain-containing protein 7 (BRD7) is downregulated and functions as a tumor suppressor in many types of cancers including breast cancer, and the dysregulation of BRD7 expression is closely related to the development and progression of breast cancer. Whereas little attention has been focused on the regulation of BRD7 protein levels in breast cancer, which needs to be further elucidated. Methods: The protein stability of BRD7 in breast cancer cells and BRD7 protein level in breast cancer tissues was examined by Western Blotting. The potential E3 ubiquitin ligase proteins that interact with the BRD7 was screened by coimmunoprecipitation combined with mass spectrometry analysis in MDA-MB-231 cells. We proved the interaction between BRD7 and tripartite motif containing 28 (TRIM28) through Co-Immunoprecipitation (Co-IP) and immunofluorescence assays. Co-IP and ubiquitination assay were used to explore the specific binding domain between BRD7 and TRIM28 and the ubiquitination site of BRD7. The effects of TRIM28 on the BRD7 protein stability and ubiquitination level was investigated by qPCR, Western Blot and Co-IP assay. CCK-8 and clone formation assays were carried out to assess the effect of TRIM28 on proliferation ability of breast cancer ells. Transwell assay and wound healing assay were used to investigate the effect of TRIM28 on breast cancer cell invasion and migration. Flow cytometry was used to detect the effect of TRIM28 on cell cycle and apoptosis of breast cancer cells. In addition, we confirmed effect of TRIM28 on tumor growth and metastasis by xenograft and metastatic mouse models. We designed some recovery assays to explore the role of recovery BRD7 in TRIM28-mediated promotion of malignant progression of breast cancer in vivo and in vitro. Finally, the clinical significance of TRIM28 and BRD7 was proved by immunohistochemistry. Results: In this study, we demonstrated that BRD7 was an unstable protein and might be regulated by ubiquitination in breast cancer; furthermore, we found that the Coiled-Coil region of TRIM28 could directly bind to N-terminal of BRD7, and TRIM28 mediates BRD7 ubiquitination and degradation dependent on K21 by acting as a potential E3 ubiquitin ligase. Moreover, TRIM28 promoted cell proliferation, migration, invasion, xenograft tumor growth and metastasis, thus playing an oncogenic role in breast cancer. Furthermore, the restoration of BRD7 expression in breast cancer significantly reversed the promotional effects of TRIM28 on malignant progression both in vitro and in vivo. In addition, TRIM28 was highly expressed in the biopsy tissues of breast cancer, and its expression was negatively correlated with BRD7 expression and positively correlated with TNM stage and poor prognosis of BC patients. Conclusions: Our findings provide a novel mechanism by which TRIM28 significantly facilitates BRD7 ubiquitination and degradation, thus promoting breast cancer malignant progression. Targeting the TRIM28/BRD7 axis might be a novel potential strategy for the clinical diagnosis and treatment of breast cancer. [ABSTRACT FROM AUTHOR]

Purpose: Increased expression of leukocyte immunoglobulin-like receptor subfamily B member 2 (LILRB2) is associated with immune evasion in breast cancer (BC). The aim of this study to elucidate the role of LILRB2 in BC progression. Methods: LILRB2 expression in tumor tissues was detected by immunohistochemical staining. Human leukocyte antigen A (HLA-A) expression in BC cells was detected by Western blotting, and HLA-A ubiquitination was detected by immunoprecipitation and histidine pulldown assay. An in-situ tumor model was established in nude BALB/c mice to verify the role of LILRB2 in immune escape. Finally, the functions and potential mechanisms of LILRB2 in BC progression were explored using in silico data. Results: LILRB2 was upregulated in BC tissues and cells, and correlated positively with poor prognosis. LILRB2 promoted BC progression by downregulating HLA-A expression. Mechanistically, LILRB2 facilitates the ubiquitination and subsequent degradation of HLA-A by promoting the interaction between the ubiquitin ligase membrane-associated ring finger protein 9 (MARCH9) and HLA-A. In syngeneic graft mouse models, LILRB2-expressing BC cells evaded CD8 + T cells and inhibited the secretion of cytokines by the cytotoxic CD8 + T cells. Conclusion: LILRB2 downregulates HLA-A to promote immune evasion in BC cells and is a promising new target for BC treatment. [ABSTRACT FROM AUTHOR]

Hereditary spastic paraplegias (HSPs) are degenerative motor neuron diseases characterized by progressive spasticity and weakness in the lower limbs. The most common form of HSP is due to SPG4 gene haploinsufficiency. SPG4 encodes the microtubule severing enzyme spastin. Although, there is no cure for SPG4-HSP, strategies to induce a spastin recovery are emerging as promising therapeutic approaches. Spastin protein levels are regulated by poly-ubiquitination and proteasomal-mediated degradation, in a neddylation-dependent manner. However, the molecular players involved in this regulation are unknown. Here, we show that the Cullin-4-RING E3 ubiquitin ligase complex (CRL4) regulates spastin stability. Inhibition of CRL4 increases spastin levels by preventing its poly-ubiquitination and subsequent degradation in spastin-proficient and in patient derived SPG4 haploinsufficient cells. To evaluate the role of CRL4 complex in spastin regulation in vivo , we developed a Drosophila melanogaster model of SPG4 haploinsufficiency which show alterations of synapse morphology and locomotor activity, recapitulating phenotypical defects observed in patients. Downregulation of the CRL4 complex, highly conserved in Drosophila , rescues spastin levels and the phenotypical defects observed in flies. As a proof of concept of possible pharmacological treatments, we demonstrate a recovery of spastin levels and amelioration of the SPG4-HSP-associated defects both in the fly model and in patient-derived cells by chemical inactivation of the CRL4 complex with NSC1892. Taken together, these findings show that CRL4 contributes to spastin stability regulation and that it is possible to induce spastin recovery and rescue of SPG4-HSP defects by blocking the CRL4-mediated spastin degradation. [ABSTRACT FROM AUTHOR]

This study investigates the molecular mechanisms behind ischaemia/reperfusion (I/R) injury in the brain, focusing on neuronal apoptosis. It scrutinizes the role of the Jun proto‐oncogene in apoptosis, involvement of SOCS1 in neural precursor cell accumulation in ischaemic regions, and the upregulation of C‐EBPβ in the hippocampus following I/R. Key to the study is understanding how Jun controls C‐EBPβ degradation via SOCS1, potentially offering new clinical treatment avenues for I/R. Techniques such as mRNA sequencing, KEGG enrichment analysis and protein–protein interaction (PPI) in mouse models have indicated involvement of Jun (AP‐1) in I/R‐induced cerebral damage. The study employs middle cerebral artery occlusion in different mouse models and oxygen–glucose deprivation/reoxygenation in cortical neurons to examine the impacts of Jun and SOCS1 manipulation on cerebral I/R injury and neuronal damage. The findings reveal that I/R reduces Jun expression in the brain, but its restoration lessens cerebral I/R injury and neuron death. Jun activates SOCS1 transcriptionally, leading to C‐EBPβ degradation, thereby diminishing cerebral I/R injury through the SOCS1/C‐EBPβ pathway. These insights provide a deeper understanding of post‐I/R cerebral injury mechanisms and suggest new therapeutic targets for cerebral I/R injury. Key points: Jun and SOCS1 are poorly expressed, and C‐EBPβ is highly expressed in ischaemia/reperfusion mouse brain tissues.Jun transcriptionally activates SOCS1.SOCS1 promotes the ubiquitination‐dependent C‐EBPβ protein degradation.Jun blunts oxygen–glucose deprivation/reoxygenation‐induced neuron apoptosis and alleviates neuronal injury.This study provides a theoretical basis for the management of post‐I/R brain injury. [ABSTRACT FROM AUTHOR]

Epigenetic alterations critically affect tumor development. Polycomb‐group complexes constitute an evolutionarily conserved epigenetic machinery that regulates stem cell fate and development. They are implicated in tumorigenesis, primarily via histone modification. Polycomb repressive complex 1 (PRC1) complexes 1–6 (PRC1.1–6) mediate the ubiquitination of histone H2A on lysine 119 (H2AK119ub). Here, we studied the functional roles of a PRC1.6 molecule, L3MBTL2, in neuroblastoma (NB) cells. L3MBTL2‐knockout and knockdown revealed that L3MBTL2 depletion suppressed NB cell proliferation via cell‐cycle arrest and gamma‐H2A.X upregulation. L3MBTL2‐knockout profoundly suppressed xenograft tumor formation. Transcriptome analysis revealed suppressed cell‐cycle‐related and activated differentiation‐related pathways. Break repair meiotic recombinase recruitment factor 1 (BRME1) and nuclear receptor interacting protein 3 (NRIP3) were notably de‐repressed by L3MBTL2‐knockout. The deletion of L3MBTL2 reduced enrichment of H2AK119ub and PCGF6 at transcriptional start site proximal regions of the targets. Add‐back studies unveiled the importance of L3MBTL2‐BRME1 and ‐NRIP3 axes for NB cell proliferation. We further manifested the association of MYCN with de‐repression of NRIP3 in an L3MBTL2‐deficient context. Therefore, this study first revealed the significance of L3MBTL2‐mediated gene silencing in MYCN‐amplified NB cells. [ABSTRACT FROM AUTHOR]

Nucleotide excision repair (NER) is a major DNA repair system and hereditary defects in this system cause critical genetic diseases (e.g. xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy). Various proteins are involved in the eukaryotic NER system and undergo several post-translational modifications. Damaged DNA-binding protein 2 (DDB2) is a DNA damage recognition factor in the NER pathway. We previously demonstrated that DDB2 was SUMOylated in response to UV irradiation; however, its physiological roles remain unclear. We herein analysed several mutants and showed that the N-terminal tail of DDB2 was the target for SUMOylation; however, this region did not contain a consensus SUMOylation sequence. We found a SUMO-interacting motif (SIM) in the N-terminal tail that facilitated SUMOylation. The ubiquitination of a SUMOylation-deficient DDB2 SIM mutant was decreased, and its retention of chromatin was prolonged. The SIM mutant showed impaired NER, possibly due to a decline in the timely handover of the lesion site to XP complementation group C. These results suggest that the SUMOylation of DDB2 facilitates NER through enhancements in ubiquitination. [ABSTRACT FROM AUTHOR]

CSA and CSB proteins are known to act in transcription-coupled DNA repair (TCR). Cockayne syndrome (CS) is a devastating multifactorial disease caused by mutations in CSA and CSB ; however the occurrence of features, for example, progeria and neurological dysfunctionalities in CS and not in the DNA repair syndrome xeroderma pigmentosum and UV-sensitive syndrome, suggests that their functions extend far beyond DNA repair. CSA and CSB function in various cellular processes, including transcription and cell cycle regulation, thus determining the need to find a common mechanism of action. We propose that, due to their involvement in ubiquitination, a key mechanism enabling the precise control of protein function and turnover, CSA and CSB act as broad regulators of essential cellular mechanisms, thus explaining the impact of their mutation in CS symptomatology. To face genotoxic stress, eukaryotic cells evolved extremely refined mechanisms. Defects in counteracting the threat imposed by DNA damage underlie the rare disease Cockayne syndrome (CS), which arises from mutations in the CSA and CSB genes. Although initially defined as DNA repair proteins, recent work shows that CSA and CSB act instead as master regulators of the integrated response to genomic stress by coordinating DNA repair with transcription and cell division. CSA and CSB exert this function through the ubiquitination of target proteins, which are effectors/regulators of these processes. This review describes how the ubiquitination of target substrates is a common denominator by which CSA and CSB participate in different aspects of cellular life and how their mutation gives rise to the complex disease CS. [ABSTRACT FROM AUTHOR]

Doxorubicin (DOX) is an anthracycline medication that is commonly used to treat solid tumors. However, DOX has limited clinical efficacy due to known cardiotoxicity. Ferroptosis is involved in DOX-induced cardiotoxicity (DIC). Although mitsugumin-53 (MG53) has cardioprotective effects and is expected to attenuate myocardial ischemic injury, its ability to inhibit DOX-induced ferroptosis has not been extensively studied. This research aims to investigate the pathophysiological impact of MG53 on DOX induced ferroptosis. Here, MG53 levels were evaluated in relation to the extent of ferroptosis by establishing in vivo and in vitro DIC mouse models. Additionally, myocardial specific MG53 overexpressing mice were used to study the effect of MG53 on cardiac function in DIC mice. The study found that the MG53 expression decreased in DOX treated mouse hearts or cardiomyocytes. However, MG53-overexpressing improved cardiac function in the DIC model and effectively reduced myocardial ferroptosis by increasing solute carrier family 7 member 11 (SLC7A11) and Glutathione peroxidase 4 (GPX4) levels, which were decreased by DOX. Mechanistically, MG53 binds to tumor suppressor 53 (p53) to regulate its ubiquitination and degradation. Ferroptosis induced by DOX was prevented by either MG53 overexpression or p53 knockdown in cardiomyocytes. The modulation of the p53/SLC7A11/GPX4 pathway by overexpression of MG53 can alleviate DOX induced ferroptosis. The study indicates that MG53 can provide protection against DIC by increasing p53 ubiquitination. These results highlight the previously unidentified role of MG53 in inhibiting ferroptosis to prevent DIC. [Display omitted] • The expression of MG53 was significantly decreased upon doxorubicin treatment. • MG53 overexpression attenuates doxorubicin-induced cardiotoxicity by inhibiting ferroptosis. • MG53 binds to p53 to regulate its ubiquitin modification. • MG53 protects against ferroptosis through the p53/SLC7A11/GPX4 pathway. [ABSTRACT FROM AUTHOR]

The systemic inflammatory response syndrome (SIRS) represents a self-amplifying cascade of inflammatory reactions and pathophysiological states triggered by infectious or non-infectious factors. The identification of disease targets and differential proteins in the liver (the unique and important immune organ) of SIRS mice treated with the lead compound D1 was conducted using the Genecards database and proteomic analysis, respectively. Subsequently, NOTCH1 was identified as the potential hub target via an intersection analysis between the aforementioned differentially expressed proteins and disease targets. Based on our previous research on the structure-activity relationship, we designed and synthesized a series of SIRS-related derivatives, wherein butyl, halogen, and ester groups were incorporated into benzophenone, aiming at exploring the anti-inflammatory protective action from the perspective of macrophage polarization. Notably, these derivatives exhibited a direct binding capability to the O-glucosylation site (SER496) or its vicinities (such as SER492, VAL485) of NOTCH1 using docking, SPR, DARTS, and CETSA techniques. Mechanistically, derivative D6 exerted anti-inflammatory effects via the dual NOTCH pathway. Firstly, it could inhibit NOTCH1 nuclear transcriptional activity, attenuate the interaction between NICD and RBPJK, concurrently suppress NF-κB and NLRP3 inflammasome (NLRP3, ASC, and cleaved CASP1) activation, and promote NICD (NOTCH1 active fragments) ubiquitination metabolism (the nuclear transcriptional pathway). Secondly, it might possess the ability to increase PGC1α level, subsequently, enhance ATP and MMP levels, mitigate ROS production, increase mitochondrial numbers, and ameliorate mitochondrial inflammatory damage (the mitochondrial pathway). Importantly, the activator Jagged1 could effectively reverse the aforementioned effects, while the inhibitor DAPT exhibited a synergistic effect, suggesting that the nuclear transcriptional regulation and mitochondrial regulation were both in a NOTCH1-dependent manner. Subsequently, it effectively alleviated the inflammatory response and preserved organ function as evidenced by up-regulating M2-type macrophage-related anti-inflammatory cytokines (IL10, TGFβ, CD206, and ARG1) and down-regulating M1-type macrophage-related pro-inflammatory cytokines (NO, IL6, IL18, iNOS, TNFα, CD86, and IL1β). In a word, derivative D6 modulated macrophage polarization and effectively mitigated SIRS by targeting inhibition of the dual NOTCH pathway. [Display omitted] In this study, we designed and synthesized a series of benzophenone derivatives targeting NOTCH1, which exhibited anti-inflammatory properties. Notably, the representative derivative D6 demonstrated the ability to promote M2 macrophage polarization while inhibiting M1 polarization, thereby restoring the delicate balance between M1 and M2 immune responses in the treatment of systemic inflammatory response syndrome (SIRS). This effect was primarily attributed to its targeted inhibition of the NOTCH1 signaling pathway at both the transcriptional and mitochondrial levels. Importantly, this discovery unveiled a novel single-target dual-regulatory model involving nuclear transcriptional regulation (NOTCH1/NF-κB/NLRP3/ubiquitination pathway) as well as mitochondrial regulation (NOTCH1/PGC1α pathway). These findings will offer valuable insights for clinical prevention and treatment strategies for SIRS while providing a theoretical foundation for the development of 4-butylbenzophenone derivatives. [ABSTRACT FROM AUTHOR]

Background Acute liver injury (ALI) is characterized by massive hepatocyte death and has high mortality and poor prognosis. Hepatocyte pyroptosis plays a key role in the pathophysiology of ALI and is involved in the inflammatory response mediated by NOD-like receptor protein 3 (NLRP3) inflammasome activation. Deltex 1 (DTX1) is a single transmembrane protein with ubiquitin E3 ligase activity and is closely involved in cell growth, differentiation, and apoptosis, as well as intracellular signal transduction. However, little is known about the influence of DTX1 on ALI. This study aimed to investigate the role of DTX1 in pyroptosis and inflammation induced by D-galactosamine (D-GalN) and tumor necrosis factoralpha (TNF-α) in human hepatocytes (LO2 cells) in vitro. Methods Cell pyroptosis was measured by flow cytometry. The levels of DTX1, pyroptosis-associated proteins, and inflammatory cytokines were detected by quantitative real-time polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay. Immunofluorescence staining, co-immunoprecipitation, ubiquitination, and luciferase reporter and chromatin immunoprecipitation assays were performed to detect the regulation between DTX1 and NLRP3 or hepatocyte nuclear factor 4 alpha (HNF4α). Analysis of variance was performed to compare groups. Results We found that DTX1 was decreased in D-GalN/TNF-α-induced LO2 cells. DTX1 overexpression significantly inhibited D-GalN/TNF-α-induced cell pyroptosis and inflammation. DTX1 interacted with NLRP3 and induced NLRP3 ubiquitination and degradation. Furthermore, by targeting NLRP3, DTX1 knockdown significantly induced cell pyroptosis and inflammation. In addition, HNF4α promoted DTX1 transcription by binding with its promoter. Conclusion Our study revealed that DTX1 suppressed D-GalN/TNF-α-induced hepatocyte pyroptosis and inflammation by regulating NLRP3 ubiquitination. [ABSTRACT FROM AUTHOR]

Epstein‒Barr virus (EBV) regulates the expression of host genes involved in functional pathways for viral infection and pathogenicity. Long noncoding RNAs (lncRNAs) have been found to be important regulators of cellular biology. However, how EBV affects host biological processes via lncRNAs remains elusive. Eukaryotic initiation factor 4A3 (EIF4A3) was recently identified as an essential controller of cell fate with an unknown role in EBV infection. Here, the expression of lncRNA brain cytoplasmic 200 (BC200) was shown to be significantly upregulated in EBV‐infected cell lines. RNA immunoprecipitation and RNA pulldown assays confirmed that BC200 bound to EIF4A3. Moreover, BC200 promoted EIF4A3 expression at the protein level but not at the mRNA level. Mechanistically, BC200 stabilized the EIF4A3 protein by impeding the K48‐linked polyubiquitination of the K195 and K198 residues of EIF4A3. In addition, RNA‐seq analysis of EBV‐positive cells with knockdown of either BC200 or EIF4A3 revealed that a broad range of cellular genes were differentially regulated, particularly those related to virus infection and immune response pathways. This study is the first to reveal the key residues involved in EIF4A3 polyubiquitination and elucidate the novel regulatory role of EBV in host gene expression via the BC200/EIF4A3 axis. These results have implications for the pathogenesis and treatment of EBV‐related diseases. [ABSTRACT FROM AUTHOR]

Background: Non‐small cell lung cancer (NSCLC) is the main type of lung cancer with high morbidity and mortality. Vascular mimicry (VM), a distinct microcirculation model in tumors that differs from classical angiogenesis, is strongly associated with poor clinical outcomes in cancer patients. miR‐491‐5p has been reported to prevent NSCLC progression, including proliferation, metastasis, and angiogenesis. However, the effect and mechanism of miR‐491‐5p on VM have not been studied in NSCLC. Methods: The expression of miR‐491‐5p was detected by quantitative reverse transcription PCR (qPCR) and fluorescence in situ hybridization (FISH). Cell counting kit‐8 (CCK‐8) and 5‐ethynyl‐2′‐deoxyuridine (EdU) staining assays were used to examine cell growth. Tube formation assay was used to assess VM in NSCLC cells. Immunohistochemistry (IHC) and western blot were performed to detect protein expression. Immunoprecipitation was used to confirm the interaction between OTU deubiquitinase 7B (OTUD7B) and vascular endothelial growth factor A (VEGFA), and the level of ubiquitinated VEGFA. A nude mouse tumorigenesis model was used to evaluate the carcinogenic capacity of NSCLC cells in vivo. Luciferase reporter assay was used to identify the potential target of miR‐491‐5p. Results: MiR‐491‐5p was found downregulated in NSCLC tissues, and miR‐491‐5p deficiency was strongly associated with angiogenesis. miR‐491‐5p mimics suppressed cell viability, migration, and VM. Conversely, an inhibitor of miR‐491‐5p had the opposite effect. OTUD7B, a deubiquitinase, was identified as a downstream target of miR‐491‐5p. A luciferase reporter assay indicated that miR‐491‐5p directly binds to the 3′UTR of OTUD7B. Moreover, mimics of miR‐491‐5p caused a significant reduction in the OTUD7B protein in NSCLC cells, and an inhibitor of miR‐491‐5p stabilized the OTUD7B protein. In addition, overexpression of OTUD7B promoted cell proliferation, migration, and VM, similar to the effects of an inhibitor of miR‐491‐5p. Further exploration revealed that OTUD7B interacts with VEGFA and that the miR‐491‐5p‐OTUD7B axis modulates the ubiquitination of VEGFA. The rescue experiment indicated that OTUD7B compromised the inhibitory effects of miR‐491‐5p on the cellular function of NSCLC cells. Conclusions: Overall, our study first proved that miR‐491‐5p impedes VM by suppressing OUTD7B and promoting the ubiquitination of VEGFA. The miR‐491‐5p/OTUD7B axis may be a novel target for antiangiogenic therapy in NSCLC. [ABSTRACT FROM AUTHOR]

Background and Aims: Gestational diabetes mellitus (GDM) is characterized by glucose intolerance that occurs during pregnancy. This study aimed to identify key ubiquitination‐related genes associated with GDM pathogenesis. Methods: Microarray data from GSE154377 was analyzed to identify differentially expressed genes (DEGs) in GDM vs normal pregnancy samples. Weighted gene co‐expression network analysis was performed on ubiquitination‐related genes. Functional enrichment, protein‐protein interaction network, and TF‐mRNA‐miRNA interaction network analyses were conducted on differentially expressed ubiquitination‐related genes (DE‐URGs). Results: We identified 2337 DEGs and 65 DE‐URGs in GDM. Functional enrichment analysis of the 65 DE‐URGs revealed involvement in protein ubiquitination and ubiquitin‐dependent catabolic processes. Protein‐protein interaction network analysis identified 8 hub genes, including MAP1LC3C, USP26, USP6, UBE2U, USP2, USP43, UCHL1, and USP44. ROC curve analysis showed these hub genes have high diagnostic accuracy for GDM (AUC > 0.6). The TF‐mRNA‐miRNA interaction network suggested USP2 and UCHL1 may be key ubiquitination genes in GDM. Conclusion: In conclusion, this study contributes to our understanding of the molecular landscape of GDM by uncovering key ubiquitination‐related genes. These findings may serve as a foundation for further investigations, offering potential biomarkers and therapeutic targets for clinical applications in GDM management. [ABSTRACT FROM AUTHOR]

Immunotherapy successfully complements traditional cancer treatment. However, primary and acquired resistance might limit efficacy. Reduced antigen presentation by MHC-I has been identified as potential resistance factor. Here we show that the epigenetic regulator ubiquitin-like with PHD and ring finger domains 1 (UHRF1), exhibits altered expression and aberrant cytosolic localization in cancerous tissues, where it promotes MHC-I ubiquitination and degradation. Cytoplasmic translocation of UHRF1 is induced by its phosphorylation on a specific serine in response to signals provided by factors present in the tumor microenvironment (TME), such as TGF-β, enabling UHRF1 to bind MHC-I. Downregulation of MHC-I results in suppression of the antigen presentation pathway to establish an immune hostile TME. UHRF1 inactivation by genetic deletion synergizes with immune checkpoint blockade (ICB) treatment and induces an anti-tumour memory response by evoking low-affinity T cells. Our study adds to the understanding of UHRF1 in cancer immune evasion and provides a potential target to synergize with immunotherapy and overcome immunotherapeutic resistance. MHC-I mediated antigen presentation is an important element of the anti-tumour immune response. Here authors identify a tumour immune escape mechanism by which the cancer cells express the ubiquitin E3 ligase UHRF1 in the cytoplasm instead of the nuclear expression pattern observed in normal tissues, and this results in degradation of MHC-I and thus diminished antigen presentation and anti-tumour T cell response. [ABSTRACT FROM AUTHOR]

Ubiquitination is an enzymatic process characterized by the covalent attachment of ubiquitin to target proteins, thereby modulating their degradation, transportation, and signal transduction. By precisely regulating protein quality and quantity, ubiquitination is essential for maintaining protein homeostasis, DNA repair, cell cycle regulation, and immune responses. Nevertheless, the diversity of ubiquitin enzymes and their extensive involvement in numerous biological processes contribute to the complexity and variety of diseases resulting from their dysregulation. The ubiquitination process relies on a sophisticated enzymatic system, ubiquitin domains, and ubiquitin receptors, which collectively impart versatility to the ubiquitination pathway. The widespread presence of ubiquitin highlights its potential to induce pathological conditions. Ubiquitinated proteins are predominantly degraded through the proteasomal system, which also plays a key role in regulating protein localization and transport, as well as involvement in inflammatory pathways. This review systematically delineates the roles of ubiquitination in maintaining protein homeostasis, DNA repair, genomic stability, cell cycle regulation, cellular proliferation, and immune and inflammatory responses. Furthermore, the mechanisms by which ubiquitination is implicated in various pathologies, alongside current modulators of ubiquitination are discussed. Enhancing our comprehension of ubiquitination aims to provide novel insights into diseases involving ubiquitination and to propose innovative therapeutic strategies for clinical conditions. [ABSTRACT FROM AUTHOR]