Echinococcus granulosus ubiquitin-conjugating enzymes (E2D2 and E2N) promote the formation of liver fibrosis in TGFß1-induced LX-2 cells.

BACKGROUND: Cystic echinococcosis (CE) is a widespread zoonosis caused by the infection with Echinococcus granulosus sensu lato (E. granulosus s.l.). CE cysts mainly develop in the liver of intermediate hosts, characterized by the fibrotic tissue that separates host organ from parasite. However, precise mechanism underlying the formation of fibrotic tissue in CE remains unclear. METHODS: To investigate the potential impact of ubiquitin-conjugating enzymes on liver fibrosis formation in CE, two members of ubiquitin-conjugating (UBC) enzyme of Echinococcus granulosus (EgE2D2 and EgE2N) were recombinantly expressed in Escherichia coli and analyzed for bioinformatics, immunogenicity, localization, and enzyme activity. In addition, the secretory pathway and their effects on the formation of liver fibrosis were also explored. RESULTS: Both rEgE2D2 and rEgE2N possess intact UBC domains and active sites, exhibiting classical ubiquitin binding activity and strong immunoreactivity. Additionally, EgE2D2 and EgE2N were widely distributed in protoscoleces and germinal layer, with differences observed in their distribution in 25-day strobilated worms. Further, these two enzymes were secreted to the hydatid fluid and CE-infected sheep liver tissues via a non-classical secretory pathway. Notably, TGFß1-induced LX-2 cells exposed to rEgE2D2 and rEgE2N resulted in increasing expression of fibrosis-related genes, enhancing cell proliferation, and facilitating cell migration. CONCLUSIONS: Our findings suggest that EgE2D2 and EgE2N could secrete into the liver and may interact with hepatic stellate cells, thereby promoting the formation of liver fibrosis.

UBE2C promotes the proliferation of acute myeloid leukemia cells through PI3K/AKT activation.

This study aims to investigate the role and mechanism of tubiquitin-conjugating enzyme E2 C (UBE2C) in acute myeloid leukemia (AML). Initially, UBE2C expression in leukemia was analyzed using the Cancer Genome Atlas database. Further, we silenced UBE2C expression using small-hairpin RNA (sh-RNA). UBE2C expression was detected via the quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blot analysis. Apoptotic events and reactive oxygen species (ROS) levels were detected by flow cytometry. A xenograft model of leukemia cells were established, and the protein levels of UBE2C, KI-67, and cleaved-caspase 3 were detected by immunohistochemistry. We reported an overexpression of UBE2C in leukemia patients and cell lines (HL60, THP-1, U937, and KG-1 cells). Moreover, a high expression level of UBE2C was correlated with a dismal prognosis in AML patients. UBE2C knockdown inhibited the viability and promoted apoptosis in AML cells by regulating the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. Furthermore, UBE2C knockdown increased cellular Fe2+ and ROS levels, and enhanced erastin-induced ferroptosis in a proteasome-dependent manner. UBE2C knockdown also suppressed the tumor formation of AML cells in the mouse model. In summary, our findings suggest that UBE2C overexpression promotes the proliferation and inhibits ferroptosis in AML cells by activating the PI3K/AKT pathway.

UBE2C: A pan-cancer diagnostic and prognostic biomarker revealed through bioinformatics analysis.

BACKGROUND: The diverse and complex attributes of cancer have made it a daunting challenge to overcome globally and remains to endanger human life. Detection of critical cancer-related gene alterations in solid tumor samples better defines patient diagnosis and prognosis, and indicates what targeted therapies must be administered to improve cancer patients' outcome. MATERIALS AND METHODS: To identify genes that have aberrant expression across different cancer types, differential expressed genes were detected within the TCGA datasets. Subsequently, the DEGs common to all pan cancers were determined. Furthermore, various methods were employed to gain genetic alterations, co-expression genes network and protein-protein interaction (PPI) network, pathway enrichment analysis of common genes. Finally, the gene regulatory network was constructed. RESULTS: Intersectional analysis identified UBE2C as a common DEG between all 28 types of studied cancers. Upregulated UBE2C expression was significantly correlated with OS and DFS of 10 and 9 types of cancer patients. Also, UBE2C can be a diagnostic factor in CESC, CHOL, GBM, and UCS with AUC = 100% and diagnose 19 cancer types with AUC ≥90%. A ceRNA network constructed including UBE2C, 41 TFs, 10 shared miRNAs, and 21 circRNAs and 128 lncRNAs. CONCLUSION: In summary, UBE2C can be a theranostic gene, which may serve as a reliable biomarker in diagnosing cancers, improving treatment responses and increasing the overall survival of cancer patients and can be a promising gene to be target by cancer drugs in the future.

Identification and validation of UBE2B as a prognostic biomarker promoting the development of esophageal carcinomas.

Introduction: Ubiquitination is a crucial biological mechanism in humans, essential for regulating vital biological processes, and has been recognized as a promising focus for cancer therapy. Our objective in this research was to discover potential enzymes associated with ubiquitination that may serve as therapeutic targets for individuals with esophageal carcinoma (ESCA). Methods: To identify genes linked to the prognosis of ESCA, we examined mRNA sequencing data from patients with ESCA in the TCGA database. Further investigation into the role of the candidate gene in ESCA was conducted through bioinformatic analyses. Subsequently, we carried out biological assays to assess its impact on ESCA development. Results: Through univariate Cox regression analysis, we identified Ubiquitin Conjugating Enzyme E2 B (UBE2B) as a potential gene associated with the prognosis of ESCA. UBE2B exhibited significant upregulation and was found to be correlated with survival outcomes in ESCA as well as other cancer types. Additionally, UBE2B was observed to be involved in various biological pathways linked to the development of ESCA, including TNF-a signaling via NF-κB, epithelial-mesenchymal transition, inflammatory response, and hypoxia. Moreover, immune-related pathways like B cell activation (GO: 0042113), B cell receptor signaling pathway (GO: 0050853) and B cell mediated immunity (GO:0019724) were also involved. It was found that high expression of UBE2B was correlated with the increase of several kinds of T cells (CD8 T cells, Th1 cells) and macrophages, while effector memory T cell (Tem) and Th17 cells decreased. Furthermore, UBE2B showed potential as a prognostic biomarker for ESCA, displaying high sensitivity and specificity. Notably, proliferation and migration in ESCA cells were effectively suppressed when the expression of UBE2B was knocked down. Conclusions: To summarize, this study has made a discovery regarding the importance of gaining new insights into the role of UBE2B in ESCA. UBE2B might be an oncogene with good ability in predicting and diagnosing ESCA. Consequently, this discovery highlights the feasibility of targeting UBE2B as a viable approach for treating patients with ESCA.

A transposon insertion in the promoter of OsUBC12 enhances cold tolerance during japonica rice germination.

Low-temperature germination (LTG) is an important agronomic trait for rice (Oryza sativa). Japonica rice generally has greater capacity for germination at low temperatures than the indica subpopulation. However, the genetic basis and molecular mechanisms underlying this complex trait are poorly understood. Here, we report that OsUBC12, encoding an E2 ubiquitin-conjugating enzyme, increases low-temperature germinability in japonica, owing to a transposon insertion in its promoter enhancing its expression. Natural variation analysis reveals that transposon insertion in the OsUBC12 promoter mainly occurs in the japonica lineage. The variation detected in eight representative two-line male sterile lines suggests the existence of this allele introgression by indica-japonica hybridization breeding, and varieties carrying the japonica OsUBC12 locus (transposon insertion) have higher low-temperature germinability than varieties without the locus. Further molecular analysis shows that OsUBC12 negatively regulate ABA signaling. OsUBC12-regulated seed germination and ABA signaling mainly depend on a conserved active site required for ubiquitin-conjugating enzyme activity. Furthermore, OsUBC12 directly associates with rice SUCROSE NON-FERMENTING 1-RELATED PROTEIN KINASE 1.1 (OsSnRK1.1), promoting its degradation. OsSnRK1.1 inhibits LTG by enhancing ABA signaling and acts downstream of OsUBC12. These findings shed light on the underlying mechanisms of UBC12 regulating LTG and provide genetic reference points for improving LTG in indica rice.

p53 accelerates endothelial cell senescence in diabetic retinopathy by enhancing FoxO3a ubiquitylation and degradation via UBE2L6.

Diabetic retinopathy (DR) is the most common ocular fundus disease in diabetic patients. Chronic hyperglycemia not only promotes the development of diabetes and its complications, but also aggravates the occurrence of senescence. Previous studies have shown that DR is associated with senescence, but the specific mechanism has not been fully elucidated. Here, we first detected the differentially expressed genes (DEGs) and cellular senescence level of db/db mouse retinas by bulk RNA sequencing. Then, we used single-cell sequencing (scRNA-seq) to identify the main cell types in the retina and analyzed the DEGs in each cluster. We demonstrated that p53 expression was significantly increased in retinal endothelial cell cluster of db/db mice. Inhibition of p53 can reduce the expression of SA-ß-Gal and the senescence-associated secretory phenotype (SASP) in HRMECs. Finally, we found that p53 can promote FoxO3a ubiquitination and degradation by increasing the expression of the ubiquitin-conjugating enzyme UBE2L6. Overall, our results demonstrate that p53 can accelerate the senescence process of endothelial cells and aggravate the development of DR. These data reveal new targets and insights that may be used to treat DR.

Discovery and characterization of noncanonical E2-conjugating enzymes.

E2-conjugating enzymes (E2s) play a central role in the enzymatic cascade that leads to the attachment of ubiquitin to a substrate. This process, termed ubiquitylation, is required to maintain cellular homeostasis and affects almost all cellular process. By interacting with multiple E3 ligases, E2s dictate the ubiquitylation landscape within the cell. Since its discovery, ubiquitylation has been regarded as a posttranslational modification that specifically targets lysine side chains (canonical ubiquitylation). We used Matrix-Assisted Laser Desorption/Ionization-Time Of Flight Mass Spectrometry to identify and characterize a family of E2s that are instead able to conjugate ubiquitin to serine and/or threonine. We used structural modeling and prediction tools to identify the key activity determinants that these E2s use to interact with ubiquitin as well as their substrates. Our results unveil the missing E2s necessary for noncanonical ubiquitylation, underscoring the adaptability and versatility of ubiquitin modifications.

Curcumin inhibits prostate cancer by upregulating miR-483-3p and inhibiting UBE2C.

Prostate cancer (PCa) is an extremely common genitourinary malignancy among elderly men. Many evidence have shown the efficacy of curcumin (CUR) in inhibiting the progression of PCa. However, the pharmacological function of CUR in PCa is still not quite clear. In this research, CUR was found to suppress the proliferation and enhance the apoptotic rate in in vitro PCa cell models in a dose- and time-dependent manner. In a xenograft animal model, the administration of CUR contributed to a significant decrease in the growth of the xenograft tumor induced by the transplanted PC-3 cells. Ubiquitin-conjugating enzyme E2 C is implicated in the modulation of multiple types of cancers. In humans, the expression levels of UBE2C are significantly higher in PCa versus benign prostatic hyperplasia. Treatment with CUR decreased the expression of UBE2C, whereas it increased miR-483-3p expression. In contrast with the control mice, the CUR-treated mice showed a significant reduction in UBE2C and Ki-67 in PCa cells. The capability of proliferation, migration, and invasion of PCa cells was inhibited by the knockdown of UBE2C mediated by siRNA. Furthermore, dual luciferase reporter gene assay indicated the binding of miR-483-3p to UBE2C. In summary, CUR exerts its antitumor effects through regulation of the miR-483-3p/UBE2C axis by decreasing UBE2C and increasing miR-483-3p. The findings may also provide new molecular markers for PCa diagnosis and treatment.

Monoubiquitination empowers ubiquitin chain elongation.

Ubiquitination often generates lysine 48-linked polyubiquitin chains that signal proteolytic destruction of the protein target. A significant subset of ubiquitination proceeds by a priming/extending mechanism, in which a substrate is first monoubiquitinated with a priming E2-conjugating enzyme or a set of E3 ARIH/E2 enzymes specific for priming. This is then followed by ubiquitin (Ub) chain extension catalyzed by an E2 enzyme capable of elongation. This report provides further insights into the priming/extending mechanism. We employed reconstituted ubiquitination systems of substrates CK1α (casein kinase 1α) and ß-catenin by Cullin-RING E3 Ub ligases (CRLs) CRL4CRBN and CRL1ßTrCP, respectively, in the presence of priming E2 UbcH5c and elongating E2 Cdc34b (cell division cycle 34b). We have established a new "apyrase chase" strategy that uncouples priming from chain elongation, which allows accurate measurement of the decay rates of the ubiquitinated substrate with a defined chain length. Our work has revealed highly robust turnover of monoubiquitinated ß-catenin that empowers efficient polyubiquitination. The results of competition experiments suggest that the interactions between the ubiquitinated ß-catenin and CRL1ßTrCP are highly dynamic. Moreover, ubiquitination of the Ub-modified ß-catenin appeared more resistant to inhibition by competitors than the unmodified substrate, suggesting tighter binding with CRL1ßTrCP. These findings support a role for conjugated Ub in enhancing interactions with E3.

Sea perch (Lateolabrax japonicus) UBC9 augments RGNNV infection by hindering RLRs-interferon response.

Small ubiquitin-like modifier (SUMO) is a reversible post-translational modification that regulates various biological processes in eukaryotes. Ubiquitin-conjugating enzyme 9 (UBC9) is the sole E2-conjugating enzyme responsible for SUMOylation and plays an important role in essential cellular functions. Here, we cloned the UBC9 gene from sea perch (Lateolabrax japonicus) (LjUBC9) and investigated its role in regulating the IFN response during red-spotted grouper nervous necrosis virus (RGNNV) infection. The LjUBC9 gene consisted of 477 base pairs and encoded a polypeptide of 158 amino acids with an active site cysteine residue and a UBCc domain. Phylogenetic analysis showed that LjUBC9 shared the closest evolutionary relationship with UBC9 from Paralichthys olivaceus. Tissue expression profile analysis demonstrated that LjUBC9 was significantly increased in multiple tissues of sea perch following RGNNV infection. Further experiments showed that overexpression of LjUBC9 significantly increased the mRNA and protein levels of RGNNV capsid protein in LJB cells infected with RGNNV, nevertheless knockdown of LjUBC9 had the opposite effect, suggesting that LjUBC9 exerted a pro-viral effect during RGNNV infection. More importantly, we found that the 93rd cysteine is crucial for its pro-viral effect. Additionally, dual luciferase assays revealed that LjUBC9 prominently attenuated the promoter activities of sea perch type Ⅰ interferon (IFN) in RGNNV-infected cells, and overexpression of LjUBC9 markedly suppressed the transcription of key genes associated with RLRs-IFN pathway. In summary, these findings elucidate that LjUBC9 impairs the RLRs-IFN response, resulting in enhanced RGNNV infection.

A Survey on the Expression of the Ubiquitin Proteasome System Components HECT- and RBR-E3 Ubiquitin Ligases and E2 Ubiquitin-Conjugating and E1 Ubiquitin-Activating Enzymes during Human Brain Development.

Human brain development involves a tightly regulated sequence of events that starts shortly after conception and continues up to adolescence. Before birth, neurogenesis occurs, implying an extensive differentiation process, sustained by changes in the gene expression profile alongside proteome remodeling, regulated by the ubiquitin proteasome system (UPS) and autophagy. The latter processes rely on the selective tagging with ubiquitin of the proteins that must be disposed of. E3 ubiquitin ligases accomplish the selective recognition of the target proteins. At the late stage of neurogenesis, the brain starts to take shape, and neurons migrate to their designated locations. After birth, neuronal myelination occurs, and, in parallel, neurons form connections among each other throughout the synaptogenesis process. Due to the malfunctioning of UPS components, aberrant brain development at the very early stages leads to neurodevelopmental disorders. Through deep data mining and analysis and by taking advantage of machine learning-based models, we mapped the transcriptomic profile of the genes encoding HECT- and ring-between-ring (RBR)-E3 ubiquitin ligases as well as E2 ubiquitin-conjugating and E1 ubiquitin-activating enzymes during human brain development, from early post-conception to adulthood. The inquiry outcomes unveiled some implications for neurodevelopment-related disorders.

The E3 ligase SMURF1 stabilizes p27 via UbcH7 catalyzed K29-linked ubiquitin chains to promote cell migration SMURF1-UbcH7 K29 ubiquitination of p27 and cell migration.

Ubiquitination is a key regulator of protein stability and function. The multifunctional protein p27 is known to be degraded by the proteasome following K48-linked ubiquitination. However, we recently reported that when the ubiquitin-conjugating enzyme UbcH7 (UBE2L3) is overexpressed, p27 is stabilized, and cell cycle is arrested in multiple diverse cell types including eye lens, retina, HEK-293, and HELA cells. However, the ubiquitin ligase associated with this stabilization of p27 remained a mystery. Starting with an in vitro ubiquitination screen, we identified RSP5 as the yeast E3 ligase partner of UbcH7 in the ubiquitination of p27. Screening of the homologous human NEDD4 family of E3 ligases revealed that SMURF1 but not its close homolog SMURF2, stabilizes p27 in cells. We found that SMURF1 ubiquitinates p27 with K29O but not K29R or K63O ubiquitin in vitro, demonstrating a strong preference for K29 chain formation. Consistent with SMURF1/UbcH7 stabilization of p27, we also found that SMURF1, UbcH7, and p27 promote cell migration, whereas knockdown of SMURF1 or UbcH7 reduces cell migration. We further demonstrated the colocalization of SMURF1/p27 and UbcH7/p27 at the leading edge of migrating cells. In sum, these results indicate that SMURF1 and UbcH7 work together to produce K29-linked ubiquitin chains on p27, resulting in the stabilization of p27 and promoting its cell-cycle independent function of regulating cell migration.

A study on genotypes and phenotypes of short stature caused by epigenetic modification gene variants.

Mendelian disorders of the epigenetic machinery (MDEMs) are caused by genetic mutations, a considerable fraction of which are associated with epigenetic modification. These MDEMs exhibit phenotypic overlap broadly characterized by multiorgan abnormalities. The variant detected in genes associated with epigenetic modification can lead to short stature accompanied with multiple system abnormalities. This study is aimed at presenting and summarizing the diagnostic rate, clinical, and genetic profile of MDEMs-associated short stature. Two hundred and fourteen short-stature patients with multiorgan abnormalities were enrolled. Clinical information and whole exome sequence (WES) were analyzed for these patients. WES identified 33 pathogenic/likely pathogenic variants in 19 epigenetic modulation genes (KMT2A, KMT2D, KDM6A, SETD5, KDM5C, HUWE1, UBE2A, NIPBL, SMC1A, RAD21, CREBBP, CUL4B, BPTF, ANKRD11, CHD7, SRCAP, CTCF, MECP2, UBE3A) in 33 patients (15.4%). Of note, 19 variants had never been reported previously. Furthermore, these 33 variants were associated with 16 different disorders with overlapping clinical features characterized by development delay/intelligence disability (31/33; 93.9%), small hands (14/33; 42.4%), clinodactyly of the 5th finger (14/33; 42.4%), long eyelashes (13/33; 39.4%), and hearing impairment (9/33; 27.3%). Additionally, several associated phenotypes are reported for the first time: clubbing with KMT2A variant, webbed neck with SETD5 variant, retinal detachment with CREBBP variant, sparse lateral eyebrow with HUWE1 variant, and long palpebral fissure with eversion of the lateral third of the low eyelid with SRCAP variant.Conclusions: Our study provided a new conceptual framework for further understanding short stature. Specific clinical findings may indicate that a short-stature patient may have an epigenetic modified gene variant.

Mechanisms and functions of SUMOylation in health and disease: a review focusing on immune cells.

SUMOylation, which is a type of post-translational modification that involves covalent conjugation of small ubiquitin-like modifier (SUMO) proteins to target substrates, regulates various important molecular and cellular processes, including transcription, the cell cycle, cell signaling, and DNA synthesis and repair. Newly synthesized SUMO is immature and cleaved by the SUMO-specific protease family, resulting in exposure of the C-terminal Gly-Gly motif to become the mature form. In the presence of ATP, mature SUMO is conjugated with the activating enzyme E1 through the cysteine residue of E1, followed by transfer to the cysteine residue of E2-conjugating enzyme Ubc9 in humans that recognizes and modifies the lysine residue of a substrate protein. E3 SUMO ligases promote SUMOylation. SUMOylation is a reversible modification and mediated by SUMO-specific proteases. Cumulative studies have indicated that SUMOylation affects the functions of protein substrates in various manners, including cellular localization and protein stability. Gene knockout studies in mice have revealed that several SUMO cycling machinery proteins are crucial for the development and differentiation of various cell lineages, including immune cells. Aberrant SUMOylation has been implicated in several types of diseases, including cancers, cardiovascular diseases, and autoimmune diseases. This review summarizes the biochemistry of SUMO modification and the general biological functions of proteins involved in SUMOylation. In particular, this review focuses on the molecular mechanisms by which SUMOylation regulates the development, maturation, and functions of immune cells, including T, B, dendritic, and myeloid cells. This review also discusses the underlying relevance of disruption of SUMO cycling and site-specific interruption of SUMOylation on target proteins in immune cells in diseases, including cancers and infectious diseases.

The membrane-associated ubiquitin ligase MARCHF8 stabilizes the human papillomavirus oncoprotein E7 by degrading CUL1 and UBE2L3 in head and neck cancer.

The human papillomavirus (HPV) oncoprotein E7 is a relatively short-lived protein required for HPV-driven cancer development and maintenance. E7 is degraded through ubiquitination mediated by cullin 1 (CUL1) and the ubiquitin-conjugating enzyme E2 L3 (UBE2L3). However, E7 proteins are maintained at high levels in most HPV-positive cancer cells. A previous proteomics study has shown that UBE2L3 and CUL1 protein levels are increased by the knockdown of the E3 ubiquitin ligase membrane-associated ring-CH-type finger 8 (MARCHF8). We have recently demonstrated that HPV16 upregulates MARCHF8 expression in HPV-positive keratinocytes and head and neck cancer (HPV+ HNC) cells. Here, we report that MARCHF8 stabilizes the HPV16 E7 protein by degrading the components of the S-phase kinase-associated protein 1-CUL1-F-box ubiquitin ligase complex in HPV+ HNC cells. We found that MARCHF8 knockdown in HPV+ HNC cells drastically decreases the HPV16 E7 protein level while increasing the CUL1 and UBE2L3 protein levels. We further revealed that the MARCHF8 protein binds to and ubiquitinates CUL1 and UBE2L3 proteins and that MARCHF8 knockdown enhances the ubiquitination of the HPV16 E7 protein. Conversely, the overexpression of CUL1 and UBE2L3 in HPV+ HNC cells decreases HPV16 E7 protein levels and suppresses tumor growth in vivo. Our findings suggest that HPV-induced MARCHF8 prevents the degradation of the HPV16 E7 protein in HPV+ HNC cells by ubiquitinating and degrading CUL1 and UBE2L3 proteins.IMPORTANCESince human papillomavirus (HPV) oncoprotein E7 is essential for virus replication; HPV has to maintain high levels of E7 expression in HPV-infected cells. However, HPV E7 can be efficiently ubiquitinated by a ubiquitin ligase and degraded by proteasomes in the host cell. Mechanistically, the E3 ubiquitin ligase complex cullin 1 (CUL1) and ubiquitin-conjugating enzyme E2 L3 (UBE2L3) components play an essential role in E7 ubiquitination and degradation. Here, we show that the membrane ubiquitin ligase membrane-associated ring-CH-type finger 8 (MARCHF8) induced by HPV16 E6 stabilizes the E7 protein by degrading CUL1 and UBE2L3 and blocking E7 degradation through proteasomes. MARCHF8 knockout restores CUL1 and UBE2L3 expression, decreasing E7 protein levels and inhibiting the proliferation of HPV-positive cancer cells. Additionally, overexpression of CUL1 or UBE2L3 decreases E7 protein levels and suppresses in vivo tumor growth. Our results suggest that HPV16 maintains high E7 protein levels in the host cell by inducing MARCHF8, which may be critical for cell proliferation and tumorigenesis.

Circ_0059457 Promotes Proliferation, Metastasis, Sphere Formation and Glycolysis in Breast Cancer Cells by Sponging miR-140-3p to Regulate UBE2C.

Circular RNA (circRNA) has been confirmed to regulate breast cancer (BC) progression. However, the role of circ_0059457 in BC progression is still unclear.The expression of circ_0059457, taspase 1 (TASP1), microRNA (miR)-140-3p and ubiquitin-binding enzyme E2C (UBE2C) was detected by quantitative real-time PCR. Cell proliferation, migration, invasion and sphere formation ability were assessed by cell counting kit-8 assay, EdU assay, wound healing assay, transwell assay and sphere formation assay. Cell glycolysis was assessed by detecting glucose uptake, lactate levels and ATP/ADP ratio. Dual-luciferase reporter assay, RIP assay, RNA pull-down assay were used to validate RNA interaction. Xenograft tumor model to assess the effect of circ_0059457 on BC tumor growth in vivo. Circ_0059457 had elevated expression in BC tissues and cells. Circ_0059457 knockdown inhibited BC cell proliferation, metastasis, sphere formation ability, and glycolysis. In terms of mechanism, circ_0059457 sponged miR-140-3p, and miR-140-3p targeted UBE2C. MiR-140-3p inhibition reversed the effect of circ_0059457 knockdown on BC cell malignant behaviors. Besides, miR-140-3p overexpression inhibited BC cell proliferation, metastasis, sphere formation ability and glycolysis, and these effects were abrogated by UBE2C enhancement. Furthermore, circ_0059457 regulated UBE2C expression through sponging miR-140-3p. Additionally, circ_0059457 knockdown obviously inhibited BC tumor growth in vivo. Circ_0059457 promoted BC progression via miR-140-3p/UBE2C axis, which provided potential target for the treatment of BC.

Structural basis for the role of C-terminus acidic tail of Saccharomyces cerevisiae ubiquitin-conjugating enzyme (Rad6) in E3 ligase (Bre1) mediated recognition of histones.

Ubiquitination of histone H2B on chromatin is key to gene regulation. E3 ligase Bre1 and E2 Rad6 in Saccharomyces cerevisiae associate together to catalyze mono-ubiquitination at histone H2BK123. Prior studies identified the role of a highly dynamic C-terminal acidic tail of Rad6 indispensable for H2BK123 mono-ubiquitination. However, the mechanistic basis for the Rad6-acidic tail role remained elusive. Using different structural and biophysical approaches, this study for the first time uncovers the direct role of Rad6-acidic tail in interaction with the Bre1 Rad6-Binding Domain (RBD) and recognition of histones surface to facilitate histone H2B mono-ubiquitination. A combination of NMR, SAXS, ITC, site-directed mutagenesis and molecular dynamics studies reveal that RBD domain of Bre1 interacts with Rad6 to stabilize the dynamics of acidic tail. This Bre1-RBD mediated stability in acidic tail of Rad6 could be one of the key factors for facilitating correct recognition of histone surface and ubiquitin-transfer at H2BK123. We provide biophysical evidence that Rad6-acidic tail and a positivity charged surface on histone H2B are involved in recognition of E2:Histones. Taken together, this study uncovers the mechanistic basis for the role of Rad6-acidic in Bre1-RBD mediated recognition of histone surface that ensure the histone H2B mono-ubiquitination.

Spatial regulation of DNA damage tolerance protein Rad5 interconnects genome stability maintenance and proteostasis networks.

The Rad5/HLTF protein has a central role in the tolerance to DNA damage by mediating an error-free mode of bypassing unrepaired DNA lesions, and is therefore critical for the maintenance of genome stability. We show in this work that, following cellular stress, Rad5 is regulated by relocalization into two types of nuclear foci that coexist within the same cell, which we termed 'S' and 'I'. Rad5 S-foci form in response to genotoxic stress and are associated with Rad5's function in maintaining genome stability, whereas I-foci form in the presence of proteotoxic stress and are related to Rad5's own proteostasis. Rad5 accumulates into S-foci at DNA damage tolerance sites by liquid-liquid phase separation, while I-foci constitute sites of chaperone-mediated sequestration of Rad5 at the intranuclear quality control compartment (INQ). Relocalization of Rad5 into each type of foci involves different pathways and recruitment mechanisms, but in both cases is driven by the evolutionarily conserved E2 ubiquitin-conjugating enzyme Rad6. This coordinated differential relocalization of Rad5 interconnects DNA damage response and proteostasis networks, highlighting the importance of studying these homeostasis mechanisms in tandem. Spatial regulation of Rad5 under cellular stress conditions thus provides a useful biological model to study cellular homeostasis as a whole.

Neddylation-dependent LSD1 destabilization inhibits the stemness and chemoresistance of gastric cancer.

Histone lysine-specific demethylase 1 (LSD1) expression has been evaluated in multiple tumors, including gastric cancer (GC). However, the mechanisms underlying LSD1 dysregulation in GC remain largely unclear. In this study, neural precursor cell-expressed developmentally down-regulated protein 8 (NEDD8) was identified to be conjugated to LSD1 at K63 by ubiquitin-conjugating enzyme E2 M (UBE2M), and this neddylated LSD1 could promote LSD1 ubiquitination and degradation, leading to a decrease of GC cell stemness and chemoresistance. Herein, our findings revealed a novel mechanism of LSD1 neddylation and its contribution to decreasing GC cell stemness and chemoresistance. Taken together, our findings may whistle about the future application of neddylation inhibitors.

UBE2J1 is the E2 ubiquitin-conjugating enzyme regulating androgen receptor degradation and antiandrogen resistance.

Prostate cancer (PCa) is primarily driven by aberrant Androgen Receptor (AR) signaling. Although there has been substantial advancement in antiandrogen therapies, resistance to these treatments remains a significant obstacle, often marked by continuous or enhanced AR signaling in resistant tumors. While the dysregulation of the ubiquitination-based protein degradation process is instrumental in the accumulation of oncogenic proteins, including AR, the molecular mechanism of ubiquitination-driven AR degradation remains largely undefined. We identified UBE2J1 as the critical E2 ubiquitin-conjugating enzyme responsible for guiding AR ubiquitination and eventual degradation. The absence of UBE2J1, found in 5-15% of PCa patients, results in disrupted AR ubiquitination and degradation. This disruption leads to an accumulation of AR proteins, promoting resistance to antiandrogen treatments. By employing a ubiquitination-based AR degrader to adeptly restore AR ubiquitination, we reestablished AR degradation and inhibited the proliferation of antiandrogen-resistant PCa tumors. These findings underscore the fundamental role of UBE2J1 in AR degradation and illuminate an uncharted mechanism through which PCa maintains heightened AR protein levels, fostering resistance to antiandrogen therapies.