The NEDD8 activating enzyme inhibitor MLN4924 mitigates doxorubicin-induced cardiotoxicity in mice.

Doxorubicin (DOX) is a widely utilized chemotherapeutic agent in clinical oncology for treating various cancers. However, its clinical use is constrained by its significant side effects. Among these, the development of cardiomyopathy, characterized by cardiac remodeling and eventual heart failure, stands as a major concern following DOX chemotherapy. In our current investigation, we have showcased the efficacy of MLN4924 in mitigating doxorubicin-induced cardiotoxicity through direct inhibition of the NEDD8-activating enzyme, NAE. MLN4924 demonstrated the ability to stabilize mitochondrial function post-doxorubicin treatment, diminish cardiomyocyte apoptosis, alleviate oxidative stress-induced damage in the myocardium, enhance cardiac contractile function, mitigate cardiac fibrosis, and impede cardiac remodeling associated with heart failure. At the mechanistic level, MLN4924 intervened in the neddylation process by inhibiting the NEDD8 activating enzyme, NAE, within the murine cardiac tissue subsequent to doxorubicin treatment. This intervention resulted in the suppression of NEDD8 protein expression, reduction in neddylation activity, and consequential manifestation of cardioprotective effects. Collectively, our findings posit MLN4924 as a potential therapeutic avenue for mitigating doxorubicin-induced cardiotoxicity by attenuating heightened neddylation activity through NAE inhibition, thereby offering a viable and promising treatment modality for afflicted patients.

UBA2 as a Prognostic Biomarker and Potential Therapeutic Target in Glioma.

BACKGROUND: Gliomas are characterized by aggressive behavior, leading to severe disability and high mortality. Ubiquitin-like modifier activating enzyme 2 (UBA2) is a subunit of the E1-activating enzyme involved in the SUMOylation (SUMO, small ubiquitin-related modifier) of numerous proteins. Although the abnormality of UBA2 is linked to the progression of various tumor types, the role of UBA2 in glioma is still unknown. METHODS: A bioinformatic analysis using several public databases was conducted to examine the expression level, clinicopathological correlations, and prognostic significance of UBA2 in glioma. The correlation between UBA2 expression and drug sensitivity in cancers was also explored. Multiple cellular experiments were conducted to validate the role of UBA2 in glioma. RESULTS: Analysis of multiple databases and cellular experiments revealed that UBA2 was overexpressed in glioma tissues and cell lines, respectively. UBA2 expression in gliomas correlated with World Health Organization (WHO) grade, IDH gene status, 1p19q deletion, histological type, and immune cell infiltration in glioma. UBA2 expression in carcinomas also correlated with drug sensitivity. Kaplan-Meier analysis revealed that high expression of UBA2 predicted poorer survival in glioma patients. A nomogram model containing UBA2 expression was constructed for clinical practice. Knockdown of UBA2 was observed to suppress glioma cell progression and sensitize glioma cells to irradiation in vitro. CONCLUSION: Overall, this research showed that UBA2 might be involved not only in the development of glioma but also in the regulation of immunity, drug sensitivity, and radiosensitivity. Therefore, UBA2 may be a potential target for therapy and a candidate biomarker for glioma diagnosis and prognosis.

[Clinical and genetic features of MDS associated with VEXAS syndrome].

VEXAS syndrome is a new disease entity characterized by the presence of cytoplasmic vacuoles in blood cells, X-linked autoinflammatory symptoms, and somatic variants in UBA1, which encodes an E1 ubiquitin-activating enzyme. Around 30-50% of VEXAS syndrome patients have concurrent MDS. We and others have recently analyzed clinical and genetic features of MDS associated with VEXAS syndrome and found that most of these cases are categorized in the low-risk subgroup with low bone marrow blast percentages. MDS associated with VEXAS syndrome tended to involve a smaller number of genes and lower-risk genetic alterations than classical MDS. In addition, anemia in MDS associated with VEXAS syndrome with active inflammation before treatment tended to respond well to steroids. In this review, we will present our recent findings together with others, focusing on the new disease entity and pathophysiology of VEXAS syndrome and clinical/genetic features of associated MDS.

The prognosis, chemotherapy and immunotherapy efficacy of the SUMOylation pathway signature and the role of UBA2 in lung adenocarcinoma.

Lung adenocarcinoma (LUAD) is one of the most common malignant tumors worldwide. Small Ubiquitin-like Modifier (SUMO)-ylation plays a crucial role in tumorigenesis. However, the SUMOylation pathway landscape and its clinical implications in LUAD remain unclear. Here, we analyzed genes involved in the SUMOylation pathway in LUAD and constructed a SUMOylation pathway signature (SUMOPS) using the LASSO-Cox regression model, validated in independent cohorts. Our analysis revealed significant dysregulation of SUMOylation-related genes in LUAD, comprising of favorable or unfavorable prognostic factors. The SUMOPS model was associated with established molecular and histological subtypes of LUAD, highlighting its clinical relevance. The SUMOPS stratified LUAD patients into SUMOPS-high and SUMOPS-low subtypes with distinct survival outcomes and adjuvant chemotherapy responses. The SUMOPS-low subtype showed favorable responses to adjuvant chemotherapy. The correlations between SUMOPS scores and immune cell infiltration suggested that patients with the SUMOPS-high subtype exhibited favorable immune profiles for immune checkpoint inhibitor (ICI) treatment. Additionally, we identified UBA2 as a key SUMOylation-related gene with an increased expression and a poor prognosis in LUAD. Cell function experiment confirmed the role of UBA2 in promoting LUAD cell proliferation, invasion, and migration. These findings provide valuable insights into the SUMOylation pathway and its prognostic implications in LUAD, paving the way for personalized treatment strategies and the development of novel therapeutic targets.

ROS-mediated up-regulation of SAE1 by Helicobacter pylori promotes human gastric tumor genesis and progression.

Helicobacter pylori (H. pylori) is a major risk factor of gastric cancer (GC). The SUMO-activating enzyme SAE1(SUMO-activating enzyme subunit 1), which is indispensable for protein SUMOylation, involves in human tumorigenesis. In this study, we used the TIMER and TCGA database to explore the SAE1 expression in GC and normal tissues and Kaplan-Meier Plotter platform for survival analysis of GC patients. GC tissue microarray and gastric samples from patients who underwent endoscopic treatment were employed to detect the SAE1expression. Our results showed that SAE1 was overexpressed in GC tissues and higher SAE1 expression was associated with worse clinical characteristics of GC patients. Cell and animal models showed that H. pylori infection upregulated SAE1, SUMO1, and SUMO2/3 protein expression. Functional assays suggested that suppression of SAE1 attenuated epithelial-mesenchymal transition (EMT) biomarkers and cell proliferation abilities induced by H. pylori. Cell and animal models of ROS inhibition in H. pylori showed that ROS could mediate the H. pylori-induced upregulation of SAE1, SUMO1, and SUMO2/3 protein. RNA sequencing was performed and suggested that knockdown of SAE1 could exert an impact on IGF-1 expression. General, increased SUMOylation modification is involved in H. pylori-induced GC.

Disease-associated polyalanine expansion mutations impair UBA6-dependent ubiquitination.

Expansion mutations in polyalanine stretches are associated with a growing number of diseases sharing a high degree of genotypic and phenotypic commonality. These similarities prompted us to query the normal function of physiological polyalanine stretches and to investigate whether a common molecular mechanism is involved in these diseases. Here, we show that UBA6, an E1 ubiquitin-activating enzyme, recognizes a polyalanine stretch within its cognate E2 ubiquitin-conjugating enzyme USE1. Aberrations in this polyalanine stretch reduce ubiquitin transfer to USE1 and, subsequently, polyubiquitination and degradation of its target, the ubiquitin ligase E6AP. Furthermore, we identify competition for the UBA6-USE1 interaction by various proteins with polyalanine expansion mutations in the disease state. The deleterious interactions of expanded polyalanine tract proteins with UBA6 in mouse primary neurons alter the levels and ubiquitination-dependent degradation of E6AP, which in turn affects the levels of the synaptic protein Arc. These effects are also observed in induced pluripotent stem cell-derived autonomic neurons from patients with polyalanine expansion mutations, where UBA6 overexpression increases neuronal resilience to cell death. Our results suggest a shared mechanism for such mutations that may contribute to the congenital malformations seen in polyalanine tract diseases.

STIGMA: Single-cell tissue-specific gene prioritization using machine learning.

Clinical exome and genome sequencing have revolutionized the understanding of human disease genetics. Yet many genes remain functionally uncharacterized, complicating the establishment of causal disease links for genetic variants. While several scoring methods have been devised to prioritize these candidate genes, these methods fall short of capturing the expression heterogeneity across cell subpopulations within tissues. Here, we introduce single-cell tissue-specific gene prioritization using machine learning (STIGMA), an approach that leverages single-cell RNA-seq (scRNA-seq) data to prioritize candidate genes associated with rare congenital diseases. STIGMA prioritizes genes by learning the temporal dynamics of gene expression across cell types during healthy organogenesis. To assess the efficacy of our framework, we applied STIGMA to mouse limb and human fetal heart scRNA-seq datasets. In a cohort of individuals with congenital limb malformation, STIGMA prioritized 469 variants in 345 genes, with UBA2 as a notable example. For congenital heart defects, we detected 34 genes harboring nonsynonymous de novo variants (nsDNVs) in two or more individuals from a set of 7,958 individuals, including the ortholog of Prdm1, which is associated with hypoplastic left ventricle and hypoplastic aortic arch. Overall, our findings demonstrate that STIGMA effectively prioritizes tissue-specific candidate genes by utilizing single-cell transcriptome data. The ability to capture the heterogeneity of gene expression across cell populations makes STIGMA a powerful tool for the discovery of disease-associated genes and facilitates the identification of causal variants underlying human genetic disorders.

Dynamic monitoring of UBA1 somatic mutations in patients with relapsing polychondritis.

BACKGROUND: Commonly clinically diagnosed with relapsing polychondritis (RP), vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome (VEXAS) is a recently identified autoinflammatory disease caused by UBA1 somatic mutations. The low frequency and dynamic changes challenge the accurate detection of somatic mutations. The present study monitored these mutations in Chinese patients with RP. We included 44 patients with RP. Sanger sequencing of UBA1 was performed using genomic DNA from peripheral blood. Droplet digital polymerase chain reaction (ddPCR) was performed to screen low-prevalence somatic variants. RESULTS: Multiple ddPCR detections were performed using available blood samples collected at different follow-up time points. Three male patients were UBA1 somatic mutation carriers. Sanger sequencing detected the somatic UBA1 variant c.122T > C (p.Met41Thr) in two male patients. Initial ddPCR confirmed the variant in the two patients, with allele fractions of 73.75% and 88.46%, respectively, while yielding negative results in other patients. Subsequent ddPCR detected the somatic variant (c.122T > C) with low prevalence (1.02%) in another male patient from blood samples collected at a different time point, and confirmed dynamically fractional abundance in one patient with VEXAS, with allele fractions of 73.75%, 61.28%, 65.01%, and 73.75%. Nine patients assessed by ddPCR at different time points remained negative. CONCLUSION: We report UBA1 variants in patients with RP in the Chinese population for the first time. Multiple ddPCR detections from samples collected at different time points can enhance sensitivity and should be considered for patients with initial negative ddPCR results.

Allelic strengths of encephalopathy-associated UBA5 variants correlate between in vivo and in vitro assays.

Protein UFMylation downstream of the E1 enzyme UBA5 plays essential roles in development and endoplasmic reticulum stress. Variants in the UBA5 gene are associated with developmental and epileptic encephalopathy 44 (DEE44), an autosomal recessive disorder characterized by early-onset encephalopathy, movement abnormalities, global developmental delay, intellectual disability, and seizures. DEE44 is caused by at least 12 different missense variants described as loss of function (LoF), but the relationships between genotypes and molecular or clinical phenotypes remain to be established. We developed a humanized UBA5 fly model and biochemical activity assays in order to describe in vivo and in vitro genotype-phenotype relationships across the UBA5 allelic series. In vivo, we observed a broad spectrum of phenotypes in viability, developmental timing, lifespan, locomotor activity, and bang sensitivity. A range of functional effects was also observed in vitro across comprehensive biochemical assays for protein stability, ATP binding, UFM1 activation, and UFM1 transthiolation. Importantly, there is a strong correlation between in vivo and in vitro phenotypes, establishing a classification of LoF variants into mild, intermediate, and severe allelic strengths. By systemically evaluating UBA5 variants across in vivo and in vitro platforms, this study provides a foundation for more basic and translational UBA5 research, as well as a basis for evaluating current and future individuals afflicted with this rare disease.

Although rare diseases only impact a small fraction of the population, they still affect hundreds of millions of people around the world. Many of these conditions are caused by variations in inherited genetic material, which nowadays can be readily detected using advanced sequencing technologies. However, establishing a connection between these genetic changes and the disease they cause often requires further in-depth study. One such rare inherited disorder is developmental and epileptic encephalopathy type 44 (DEE44), which is caused by genetic variations within the gene for UBA5 (short for ubiquitin-like modifier activating enzyme 5). For DEE44 to occur, both copies of the gene for UBA5, known as alleles, must contain one or more detrimental variation. Although all these variations prevent UBA5 from working correctly, the level of disruption they cause, known as allelic strength, varies between them. However, it remained unclear whether the severity of the DEE44 disease directly corresponds with the allelic strength of these variants. To answer this question, Pan et al. tested how different genetic variants found in patients with DEE44 affected the behavior and health of fruit flies. These results were then compared against in vitro biochemical assays testing how alleles containing these variants impacted the function of UBA5. When the fly gene for the enzyme was replaced with the human gene containing variations associated with DEE44, flies exhibited changes in their survival rates, developmental progress, lifespan, and neurological well-being. However, not all of the variants caused ill effects. Using this information, the patient variants were classified into three categories based on the severity of their effect: mild, intermediate, and severe. Biochemical assays supported this classification and revealed that the variants that caused more severe symptoms tended to inhibit the activity of UBA5 more significantly. Pan et al. further analyzed the nature of the variants in the patients and showed that most patients typically carried one mild and one strong variant, although some individuals did have two intermediate variants. Notably, no patients carried two severe variants. This indicates that DEE44 is the result of UBA5 only partially losing its ability to work correctly. The study by Pan et al. provides a framework for assessing the impact of genetic variants associated with DEE44, aiding the diagnosis and treatment of the disorder. However, further research involving more patients, more detailed clinical data, and testing other newly identified DEE44-causing variants is needed to solidify the correlation between allelic strength and disease severity.

UBE2A/B is the trans-acting factor mediating mechanotransduction and contact inhibition.

Mechanotransduction and contact inhibition (CI) control gene expression to regulate proliferation, differentiation, and even tumorigenesis of cells. However, their downstream trans-acting factors (TAFs) are not well known due to a lack of a high-throughput method to quantitatively detect them. Here, we developed a method to identify TAFs on the cis-acting sequences that reside in open chromatin or DNaseI-hypersensitive sites (DHSs) and to detect nucleocytoplasmic shuttling TAFs using computational and experimental screening. The DHS-proteomics revealed over 1000 potential mechanosensing TAFs and UBE2A/B (Ubiquitin-conjugating enzyme E2 A) was experimentally identified as a force- and CI-dependent nucleocytoplasmic shuttling TAF. We found that translocation of YAP/TAZ and UBE2A/B are distinctively regulated by inhibition of myosin contraction, actin-polymerization, and CI depending on cell types. Next-generation sequence analysis revealed many downstream genes including YAP are transcriptionally regulated by ubiquitination of histone by UBE2A/B. Our results suggested a YAP-independent mechanotransduction and CI pathway mediated by UBE2A/B.

UBE1C is upregulated and promotes neddylation of p53 in lung cancer.

NEDDylation is a type of protein post-translational modification that has high similarity to ubiquitination. UBE1C encodes NEDDylation E1 enzyme, locates at chromatin region 3p14.1 and shows high gene dosage amplification frequency in both Asian and Caucasian lung cancer patients. However, its NEDDylation substrates and roles in tumorigenesis remain elucidated. In this study, we aim to investigate the oncogenic role of UBE1C and its involvement in how NEDDylation regulates p53 in lung cancer. We found that UBE1C mRNA overexpression and DNA amplification in most of the lung cell lines and cancer patients. Patients with UBE1C overexpression showed poor prognosis. Moreover, we demonstrated that overexpression of UBE1C and NEDD8, a NEDDylation moiety, resulted in the p53 NEDDylation with inhibition of p53 acetylation at K373 residue. Importantly, UBE1C-mediated NEDDylation downregulated the transcriptional activity of p53 by inhibiting p53 ability to target promoter regions of its downstream transcription targets, consequently inhibiting the promoter activities and the expression of mRNA and protein of the p53 downstream genes including p21 and PTEN. In addition, UBE1C and NEDD8 overexpression promoted migration, invasion, and proliferation of lung cancer cells. Our findings suggest that UBE1C acts as an oncogene with prognostic potential and highlight a potential role of UBE1C-mediated NEDDylation in downregulation of p53 transcriptional activity in lung cancer.

Involvement in Fertilization and Expression of Gamete Ubiquitin-Activating Enzymes UBA1 and UBA6 in the Ascidian Halocynthia roretzi.

The extracellular ubiquitin-proteasome system is involved in sperm binding to and/or penetration of the vitelline coat (VC), a proteinaceous egg coat, during fertilization of the ascidian (Urochordata) Halocynthia roretzi. It is also known that the sperm receptor on the VC, HrVC70, is ubiquitinated and degraded by the sperm proteasome during the sperm penetration of the VC and that a 700-kDa ubiquitin-conjugating enzyme complex is released upon sperm activation on the VC, which is designated the "sperm reaction". However, the de novo function of ubiquitin-activating enzyme (UBA/E1) during fertilization is poorly understood. Here, we show that PYR-41, a UBA inhibitor, strongly inhibited the fertilization of H. roretzi. cDNA cloning of UBA1 and UBA6 from H. roretzi gonads was carried out, and their 3D protein structures were predicted to be very similar to those of human UBA1 and UBA6, respectively, based on AlphaFold2. These two genes were transcribed in the ovary and testis and other organs, among which the expression of both was highest in the ovary. Immunocytochemistry showed that these enzymes are localized on the sperm head around a mitochondrial region and the follicle cells surrounding the VC. These results led us to propose that HrUBA1, HrUBA6, or both in the sperm head mitochondrial region and follicle cells may be involved in the ubiquitination of HrVC70, which is responsible for the fertilization of H. roretzi.

IGF2BP3 Regulates TMA7-mediated Autophagy and Cisplatin Resistance in Laryngeal Cancer via m6A RNA Methylation.

Translation machinery associated 7 homolog (TMA7) is closely related to proliferation-related diseases. However, the function and regulatory mechanism of TMA7 in laryngeal squamous cell carcinoma (LSCC) remain unclear. The present study aimed to investigate the effect of TMA7 on the occurrence and development of LSCC and to study the mechanism of TMA7. TMA7 is upregulated in LSCC tissues and associated with poor prognosis. After TMA7 downregulation, the autophagy level was increased, and the proliferation, migration, and invasion of LSCC cells were inhibited. The m6A methylated reader IGF2BP3 enhanced the stability of TMA7 and reduced the level of autophagy. TMA7 interacted directly with UBA2. Furthermore, the activation of the IGF2BP3-regulated TMA7-UBA2-PI3K pathway is the primary mechanism by which TMA7 inhibits autophagy and promotes the progression of LSCC. The current study revealed that IGF2BP3-mediated TMA7 m6A modification promotes LSCC progression and cisplatin-resistance through UBA2-PI3K pathway, providing new insights into the autophagy-related mechanism, potential biomarkers, and therapeutic targets for LSCC.

E3-ubiquitin ligases and recent progress in osteoimmunology.

Ubiquitin-mediated proteasomal degradation is a post-transcriptional protein modification that is comprised of various components including the 76-amino acid protein ubiquitin (Ub), Ub-activating enzyme (E1), Ub-conjugating enzyme (E2), ubiquitin ligase (E3), deubiquitinating enzyme (DUB) and proteasome. We and others have recently provided genetic evidence showing that E3-ubiquitin ligases are associated with bone metabolism, the immune system and inflammation through ubiquitylation and subsequent degradation of their substrates. Dysregulation of the E3-ubiquitin ligase RNF146-mediated degradation of the adaptor protein 3BP2 (SH3 domain-binding protein 2) causes cherubism, an autosomal dominant disorder associated with severe inflammatory craniofacial dysmorphia syndrome in children. In this review, on the basis of our discoveries in cherubism, we summarize new insights into the roles of E3-ubiquitin ligases in the development of human disorders caused by an abnormal osteoimmune system by highlighting recent genetic evidence obtained in both human and animal model studies.

Novel Somatic UBA1 Variant in a Patient With VEXAS Syndrome.

OBJECTIVE: Somatic mutations in UBA1 have recently been causally linked to a severe adult-onset inflammatory condition referred to as VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Ubiquitin-activating enzyme E1 (UBA-1) is of fundamental importance to the modulation of ubiquitin homeostasis and to the majority of downstream ubiquitylation-dependent cellular processes. Direct sequencing analysis of exon 3 containing the prevalent variants p.Met41Leu, p.Met41Val, and/or p.Met41Thr is usually used to confirm the disease-associated mutations. METHODS: We studied the clinical, biochemical, and molecular genetic characteristics of a 59-year-old man with a 2-year history of arthritis, fever, night sweats, nonspecific skin rash, lymphadenopathy, and myelodysplastic syndrome with multilineage dysplasia. RESULTS: The mutational analysis revealed a previously undescribed sequence variant c.1430G>C in exon 14 (p.Gly477Ala) in the gene UBA1. In vitro enzymatic analyses showed that p.Gly477Ala led to both decreased E1 ubiquitin thioester formation and E2 enzyme charging. CONCLUSION: We report a case of a patient of European ancestry with clinical manifestations of VEXAS syndrome associated with a newly identified dysfunctional UBA-1 enzyme variant. Due to the patient's insufficient response to various immunosuppressive treatments, allogeneic hematopoietic stem cell transplantation was performed, which resulted in significant improvement of clinical and laboratory manifestations of the disease.

Increased Small Ubiquitin-like Modifier-Activating Enzyme SAE1 Promotes Hepatocellular Carcinoma by Enhancing mTOR SUMOylation.

SUMOylation, one of the most important posttranslational modifications of proteins, plays an essential role in various biological processes; however, enzymes that control SUMOylation in hepatocellular carcinoma (HCC) are still unclear. Comprehensive exploration of the expression and clinical significance of SUMO enzymes in HCC would be of great value. Here, we obtained the gene expression profile of each small ubiquitin-like modifier (SUMO) protein and the corresponding clinical information from The Cancer Genome Atlas. We found that all SUMO enzymes were significantly increased in HCC tissues compared with that in adjacent nontumorous tissues. We identified a 6-gene prognostic signature, including SAE1, PIAS2, PIAS3, SENP3, SENP5, and UBC9, that could effectively predict the overall survival in patients with HCC. Specifically, SAE1 was the most valuable prognostic indicator. In 282 clinical samples, we found that SAE1 was closely related to the clinicopathologic parameters and prognosis of patients with HCC. In vitro and in vivo studies showed that SAE1 knockdown inhibits the proliferation, migration, and invasion of HCC cells. Mechanistically, we confirmed that SAE1 plays a role in driving HCC progression, which is largely dependent on the SUMOylation of mTOR signaling. In conclusion, our study revealed that the expression of SUMO enzymes, especially SAE1, is highly associated with HCC development and acts as a promising prognostic predictor.

Novel causative variants of VEXAS in UBA1 detected through whole genome transcriptome sequencing in a large cohort of hematological malignancies.

UBA1 is an X-linked gene and encodes an ubiquitin-activating enzyme. Three somatic mutations altering the alternative start codon (M41) in UBA1 in hematopoietic precursor cells have recently been described, resulting in a syndrome of severe inflammation, cytopenias, and the presence of intracellular vacuoles in hematopoietic precursors - termed VEXAS syndrome, a predominantly male disease. Here we present a patient with clinical features of VEXAS who harbored two novel somatic variants in UBA1 (I894S and N606I). To better understand the clinical relevance and biological consequences of non-M41 (UBA1non-M41) variants, we analyzed the whole genome and transcriptome data of 4168 patients with hematological malignancies and detected an additional 16 UBA1non-M41 putative somatic variants with a clear sex-bias in patients with myeloid malignancies. Patients diagnosed with myeloid malignancies carrying UBA1non-M41 putative somatic variants either had vacuoles or immunodysregulatory symptoms. Analysis of the transcriptome confirmed neutrophil activation in VEXAS patients compared to healthy controls but did not result in a specific transcriptomic signature of UBA1M41 patients in comparison with MDS patients. In summary, we have described multiple putative novel UBA1non-M41 variants in patients with various hematological malignancies expanding the genomic spectrum of VEXAS syndrome.

Estimated Prevalence and Clinical Manifestations of UBA1 Variants Associated With VEXAS Syndrome in a Clinical Population.

Importance: VEXAS (vacuoles, E1-ubiquitin-activating enzyme, X-linked, autoinflammatory, somatic) syndrome is a disease with rheumatologic and hematologic features caused by somatic variants in UBA1. Pathogenic variants are associated with a broad spectrum of clinical manifestations. Knowledge of prevalence, penetrance, and clinical characteristics of this disease have been limited by ascertainment biases based on known phenotypes. Objective: To determine the prevalence of pathogenic variants in UBA1 and associated clinical manifestations in an unselected population using a genomic ascertainment approach. Design, Setting, and Participants: This retrospective observational study evaluated UBA1 variants in exome data from 163 096 participants within the Geisinger MyCode Community Health Initiative. Clinical phenotypes were determined from Geisinger electronic health record data from January 1, 1996, to January 1, 2022. Exposures: Exome sequencing was performed. Main Outcomes and Measures: Outcome measures included prevalence of somatic UBA1 variation; presence of rheumatologic, hematologic, pulmonary, dermatologic, and other findings in individuals with somatic UBA1 variation on review of the electronic health record; review of laboratory data; bone marrow biopsy pathology analysis; and in vitro enzymatic assays. Results: In 163 096 participants (mean age, 52.8 years; 94% White; 61% women), 11 individuals harbored likely somatic variants at known pathogenic UBA1 positions, with 11 of 11 (100%) having clinical manifestations consistent with VEXAS syndrome (9 male, 2 female). A total of 5 of 11 individuals (45%) did not meet criteria for rheumatologic and/or hematologic diagnoses previously associated with VEXAS syndrome; however, all individuals had anemia (hemoglobin: mean, 7.8 g/dL; median, 7.5 g/dL), which was mostly macrocytic (10/11 [91%]) with concomitant thrombocytopenia (10/11 [91%]). Among the 11 patients identified, there was a pathogenic variant in 1 male participant prior to onset of VEXAS-related signs or symptoms and 2 female participants had disease with heterozygous variants. A previously unreported UBA1 variant (c.1861A>T; p.Ser621Cys) was found in a symptomatic patient, with in vitro data supporting a catalytic defect and pathogenicity. Together, disease-causing UBA1 variants were found in 1 in 13 591 unrelated individuals (95% CI, 1:7775-1:23 758), 1 in 4269 men older than 50 years (95% CI, 1:2319-1:7859), and 1 in 26 238 women older than 50 years (95% CI, 1:7196-1:147 669). Conclusions and Relevance: This study provides an estimate of the prevalence and a description of the clinical manifestations of UBA1 variants associated with VEXAS syndrome within a single regional health system in the US. Additional studies are needed in unselected and genetically diverse populations to better define general population prevalence and phenotypic spectrum.

VEXAS syndrome in dermatology.

Vacuoles, E1 enzyme, x-linked, autoinflammatory, and somatic mutation (VEXAS) syndrome is a recently described disease associated with high morbidity and mortality. VEXAS syndrome results from a somatic mutation affecting UBA1, a gene that codes for the E1 ubiquitin activating protein. Loss of UBA1 leads to a broad range of inflammatory conditions and a clinical course often refractive to therapy. We present the cases of two patients who demonstrated a rapid decline in overall health, decreased energy, arthralgias, anemia, fever, increased inflammatory markers, and characteristic bone marrow. Importantly, dermatologic assessment revealed skin biopsy findings of medium-vessel vasculitis and neutrophilic infiltration. Following blood analysis, both patients were diagnosed with VEXAS syndrome resulting from a mutation in the UBA1 gene. Our report highlights the pivotal role dermatologists have in early diagnosis of patients with VEXAS syndrome.

Emerging role of protein modification by UFM1 in cancer.

Ubiquitin-fold modifier 1 (UFM1) is a newly identified ubiquitin-like protein. Like ubiquitin, UFM1 is conjugated to its target proteins through a three-step enzyme system: UBA5 (E1), UFC1 (E2), and UFL1 (E3), but with an additional essential component, UFBP1. This protein modification by UFM1 (ufmylation) can be reversed by UFM1-specific proteases (UFSPs). So far only a handful of target proteins for ufmylation have been identified, and they are mostly associated with either promotion or suppression of tumorigenesis. Here, we summarize the recent progress in the knowledge of tumor-suppressive and tumorigenic functions of ufmylation as well as in the development of therapeutic drugs against ufmylation-associated cancer.