The ubiquitin codes in cellular stress responses

Fluorescence-Coupled Ubiquitination Assay as a High-Throughput Screening Strategy for Novel Cereblon Degraders

Cereblon (CRBN)-based protein degradation, via molecular glue degraders (MGDs) and proteolysis-targeting chimeras (PROTACs), is a promising cancer treatment strategy in targeted protein degradation (TPD). However, novel degraders discovery remains limited due to the lack of robust, high-throughput screening (HTS) methods for processing pools of purified compounds or complex chemical synthesis mixtures. Here, we introduce an innovative HTS strategy that employs a highly sensitive, fluorescence-coupled ubiquitination assay to identify CRBN-based degraders. This approach tracks ubiquitinated target proteins via gel-based analyses, and thereby progressively narrows down the list of potential degrader molecules from large-scale compound libraries or chemical reaction mixtures. Using this strategy, we identified LL-BPTF-8, a promising lead compound of PROTAC degrader with high potency and selectivity that targets the bromodomain PHD finger transcription factor (BPTF). Overall, our method offers a low-cost, rapid, and versatile platform for the HTS of protein degrader candidates, significantly streamlining the discovery of novel degraders.

Spatiotemporal deciphering of dynamic the FUS interactome during liquid-liquid phase separation in living cells

Liquid-liquid phase separations (LLPS) are membraneless organelles driven by biomolecule assembly and are implicated in cellular physiological activities. However, spatiotemporal deciphering of the dynamic proteome in living cells during LLPS formation remains challenging. Here, we introduce the Composition of LLPS proteome Assembly by Proximity labeling-assisted Mass spectrometry (CLAPM). We demonstrate that CLAPM can instantaneously label and monitor the FUS interactome shifts within intracellular droplets undergoing spatiotemporal LLPS. We report 129, 182 and 822 proteins specifically present in the LLPS droplets of HeLa, HEK 293 T and neuronal cells respectively. CLAPM further categorizes spatiotemporal dynamic proteome in droplets for living neuronal cells and identifies 596 LLPS-aboriginal proteins, 226 LLPS-dependent proteins and 58 LLPS-sensitive proteins. For validation, we uncover 11 previously unknown LLPS proteins in vivo. CLAPM provides a versatile tool to decipher proteins involved in LLPS and enables the accurate characterization of dynamic proteome in living cells.

Heat Shock Strengthens the Protective Potential of MSCs in Liver Injury by Promoting EV Release Through Upregulated Autophagosome Formation

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) show powerful potential in the treatment of multiple diseases. However, the low yield of MSC-EVs severely restricts their clinical application. Here, heat shock (HS), a moderate external stimulus, can enhance EVs release of MSCs by upregulating autophagosome formation. Mechanistically, HS elevates TRPV2 expression to induce Ca2+ influx and then promotes the activity of two succinylases, SUCLG2 and OXCT1, followed by increasing the succinylation of YWHAZ (a 14-3-3 protein) at lysine 11 (K11). Acting as an adaptor protein, YWHAZ's succinylation at K11 inhibits its degradation, reinforcing YWHAZ-ULK1 binding, which upregulates ULK1 S555 phosphorylation to promote autophagosome formation and enhance EV release of MSCs. Additionally, the improved therapeutic efficacy of HS-treated MSCs via EV release has been shown in two liver injury models-hepatic ischemia/reperfusion injury (HIRI) and acetaminophen-induced liver injury. These findings proved that HS, an easily implementable and cost-effective method, can be used to elevate MSC-EV yield in mass production.

Distinct Stress Regulators in the CRL Family: Emerging Roles of F-Box Proteins: Cullin-RING Ligases and Stress-Sensing

Cullin-RING ligases (CRLs) are central regulators of environmental and cellular stress responses, orchestrating diverse processes through the ubiquitination of substrate proteins. As modular complexes, CRLs employ substrate-specific adaptors to target proteins for degradation and other ubiquitin-mediated processes, enabling dynamic adaptation to environmental cues. Recent advances have highlighted the largest CRL subfamily SCF (Skp1-cullin-F-box) in environmental sensing, a role historically underappreciated for SCF ubiquitin ligases. Notably, emerging evidence suggests that the F-box domain, a 50-amino acid motif traditionally recognized for mediating protein-protein interactions, can act as a direct environmental sensor due to its ability to bind heavy metals. Despite these advances, the roles of many CRL components in environmental sensing remain poorly understood. This review provides an overview of CRLs in stress response regulation and emphasizes the emerging functions of F-box proteins in environmental adaptation.

SETD7 drives diabetic endothelial dysfunction through FBXO45-mediated GPX4 ubiquitylation

BACKGROUND

Vasculopathy is the most prevalent complication of diabetes. Endothelial damage, a primary contributor to hyperglycemic vascular complications, impacts macro- and micro-vasculatures, causing functional impairment of multiple organs. SETD7 was initially identified as a transcriptional activator based on its ability to methylate histone 3 lysine 4. However, its function in the context of diabetic endothelial dysfunction remains poorly understood. This study aims to elucidate the involvement and underlying mechanisms of SETD7 in diabetic endothelial dysfunction.

METHODS

SETD7 knockout mice were generated to investigate the effects of SETD7 on Streptozotocin (STZ)-induced hyperglycemia and vascular endothelial injury. Endothelial-specific SETD7 interruption adeno-associated virus (AAV) system was utilized to investigate the effects of SETD7 on diabetic vascular endothelial injury in BKS-DB(Lepr) KO/KO (db/db) mice. In vitro manipulation of SETD7 activation or knockdown was conducted to assess its regulation on the lipid peroxidation, oxidative stress, and cell function of primary rat aortic endothelial cells (RAECs) under high glucose conditions.

RESULTS

Our study revealed that knockout and endothelial deficiency of SETD7 partially restored damaged vascular function and attenuated the inflammatory response caused by high glucose in both STZ-induced and db/db mice. Moreover, SETD7 activation aggravated oxidative stress injury and resulted in profound dysfunction through Glutathione Peroxidase 4 (GPX4)-mediated lipid peroxidation in RAECs. Mechanistically, SETD7 deficiency reduced p53 mono-methylation and blocked FBXO45 transcription, thereby inhibiting the protein degradation of GPX4 and subsequent lipid peroxidation as well as oxidative stress.

CONCLUSIONS

In summary, our study demonstrates that SETD7-p53-FBXO45-GPX4 is involved in high glucose-induced oxidative stress injury and exacerbated endothelial dysfunction, which offering great significance for mitigating hyperglycemia-induced endothelial damage.

Integrated quantitative proteomics and phosphoproteomics analysis reveals USP46-POU4F1-HPSE signaling axis in the pathogenesis of Hirschsprung disease

Hirschsprung's disease (HSCR) is a congenital disorder characterized by the absence of enteric ganglion cells in the distal colon, resulting in functional intestinal obstruction. While genetic mutations and microenvironmental imbalances have been implicated in HSCR, the underlying molecular mechanisms are not fully understood. This study uses integrated quantitative proteomics and phosphoproteomics analyses to characterize the differential protein profiles and phosphorylation modifications associated with HSCR. These findings reveal significant dysregulation of the extracellular matrix (ECM) remodelling pathway, suggesting its potential involvement in HSCR pathogenesis. Notably, the deubiquitinating enzyme USP46 is found to be significantly reduced in the aganglionic segments of HSCR patients. Through IP-MS, GST pull-down, and co-immunoprecipitation assays, it is demonstrated that USP46 interacts with the transcription factor POU4F1. Mechanistically, USP46 stabilizes POU4F1 via deubiquitination, increasing its binding to the heparanase (HPSE) promoter and increasing HPSE expression, which in turn promotes ECM remodelling and neural cell migration. The role of the USP46-POU4F1-HPSE signaling axis in HSCR pathogenesis is confirmed via chromatin immunoprecipitation-qPCR, luciferase reporter assays, and transwell migration assays. This study elucidates a novel regulatory mechanism linking USP46-mediated protein stabilization to ECM dynamics and neural cell migration, offering new insights into HSCR pathogenesis and potential therapeutic targets.

March2 Alleviates Aortic Aneurysm/Dissection by Regulating PKM2 Polymerization

BACKGROUND

Aortic aneurysm/dissection (AAD) is a life-threatening disease lacking effective pharmacological treatment. Protein ubiquitination plays a pivotal role in cardiovascular diseases. However, the possible contribution of the E3 ubiquitin ligase March2 (membrane-associated RING [really interesting new gene] finger protein 2) to the cause of AAD remains elusive.

METHODS

Integrated single-cell RNA sequencing analysis was conducted in human AAD tissues. Based on the screening results, we generated a mouse line of smooth muscle cell-specific March2 knockout. β-Aminopropionitrile monofumarate was used to establish AAD. Cleavage under targets and tagmentation and cleavage under targets and tagmentation-quantitative polymerase chain reaction were performed to identify possible target genes for histone H3K18 lactylation.

RESULTS

March2 expression was downregulated in aorta from patients with AAD or β-aminopropionitrile monofumarate-induced AAD mice. β-Aminopropionitrile monofumarate-induced AAD was significantly accentuated in March2 global (March2-/-) and vascular smooth muscle cell-specific deletion (March2fl/fl; TaglnCre) mice, whereas the AAD pathology was rescued by rAAV9-SM22α (smooth muscle 22α)-March2 (recombinant adeno-associated virus serotype 9 expressing Flag-tagged March2 under SM22α promoter). March2 interacted with PKM2 (pyruvate kinase M2) to promote K33-linked polyubiquitination. Deficiency of March2 lessened PKM2 dimer-to-tetramer conversion in AAD and overtly exacerbated AAD-induced histone H3K18 lactylation in vascular smooth muscle cells by fostering glucose metabolism reprogramming, thereby promoting p53-driven apoptotic transcriptional response-a hallmark of AAD pathogenesis. TEPP-46 (tetraethyl pyrophosphate), a PKM2-specific activator, pronouncedly alleviated March2 deficiency-deteriorated AAD pathology.

CONCLUSIONS

Our findings demonstrated that March2 is a novel endogenous defender that prevents AAD by inhibiting vascular smooth muscle cell apoptosis, suggesting that March2 represents a potential therapeutic target for AAD.

Ecotoxicological responses of marine fish to the organophosphate flame-retardant tris (2-chloroisopropyl) phosphate (TCPP) dietary exposure: Juvenile gilthead seabream (Sparus aurata) as a case study

High Production Volume Chemicals (HPVCs) are contaminants that pose serious threats to aquatic environments and species that inhabit them, given their massive production and ubiquitous distribution across biological compartments. Among them, organophosphate esters (OPEs) are of particular concern, as they are widely used as plasticizers and flame-retardants, and linked to various forms of toxicity in marine organisms. In this study, we investigated the ecotoxicological response of juvenile gilthead seabream Sparus aurata to the OPE tris (2-chloroisopropyl) phosphate (TCPP) following chronic dietary exposure to three different concentrations (low, D1: 0.2 mg kg-1; ecologically relevant, D2: 2 mg kg-1; and high, D3: 10 mg kg-1). Different biomarkers indicative of antioxidant defence mechanisms (catalase, CAT, glutathione S-transferase, GST, activities), metabolism (citrate synthase, CS, lactate dehydrogenase, LDH, activities) and endocrine disruption (vitellogenin content, VTG), as well as cell (lipid peroxidation levels, LPO) and protein damage (ubiquitin content, UBI) were analyzed in liver and muscle to assess TCPP toxicity. High concentrations of TCPP affected S. aurata growth, but not overall fitness condition. Furthermore, metabolic disruption and severe oxidative damages were observed, regardless of exposure dose. VTG content significantly decreased after exposure to all TCPP dosages, indicating a possible masculinization effect. These findings provide new insights to the scientific knowledge on TCPP ecotoxicological attributes and impacts on marine ichthyofauna. In addition, our results confirm the relevance of conducting integrated multi-biomarker approaches to disclose the ecotoxicological effects of poorly studied chemical contaminants and, ultimately, implement wastewater treatment strategies and legislation to protect marine ecosystems from pollution.

Chlamydomonas FBB18 is a ubiquitin-like protein essential for the cytoplasmic preassembly of various ciliary dyneins

Motile cilia are organelles found on many eukaryotic cells that play critical roles in development and fertility. Human CFAP298 has been implicated in the transport/assembly of ciliary dyneins, and defects in this protein cause primary ciliary dyskinesia. However, neither the exact function nor the structure of CFAP298 have been elucidated. Here, we took advantage of Chlamydomonas, a ciliated alga, to study the structure and function of FBB18, an ortholog of CFAP298. Multiple ciliary dyneins were greatly reduced in cilia of Chlamydomonas fbb18 mutants. In addition, we found that both the stability of ciliary dynein heavy chains (HCs) and the association between HCs and intermediate/light chains (IC/LCs) are greatly reduced in fbb18 cytoplasm, strongly suggesting that FBB18 functions in the cytoplasmic assembly (the so-called "preassembly") of dynein complexes from HC/IC/LCs. Furthermore, X-ray crystallography revealed that FBB18 forms a bilobed structure with globular domains at both ends of the molecule, connected by an α-helical bundle. Unexpectedly, one globular domain shows high similarity to ubiquitin, a small protein critical for the modification of a variety of protein complexes, and this ubiquitin-like domain is indispensable for the molecular function of FBB18. Our results demonstrate that FBB18, a specialized member of the ubiquitin-like protein family, plays a critical role in dynein preassembly, most likely by mediating diverse interactions between dynein HCs, molecular chaperone(s), and other preassembly factor(s) using the ubiquitin-like domain as well as other regions, and by facilitating the proper folding of dynein HCs.

Brucella suis S2 strain inhibits IRE1/caspase-12/caspase-3 pathway-mediated apoptosis of microglia HMC3 by affecting the ubiquitination of CALR

Neurobrucellosis represents a severe complication of brucellosis, posing a considerable risk to human health and quality of life. This condition arises from an increased susceptibility to chronic Brucella infection, a significant clinical challenge. One key factor contributing to chronic neurobrucellosis is the regulation of microglial apoptosis by Brucella; however, the exact molecular mechanisms remain largely unresolved. In this study, human microglial clone 3 (HMC3) cells were infected with Brucella suis vaccine strain S2 (B. suis S2) at varying multiplicity of infection (MOI) and durations to assess its effects on the IRE1/caspase-12/caspase-3 signaling pathway. Following the suppression of this pathway by B. suis S2, calreticulin (CALR) was identified through ubiquitin-modified proteomics (data accessible via ProteomeXchange, identifier PXD056006). To further investigate, CALR-overexpression and knockdown HMC3 cell lines were infected with B. suis S2 to elucidate the mechanism by which B. suis S2 inhibits apoptosis in HMC3 cells. In conclusion, our findings demonstrate that B. suis S2 suppresses HMC3 cell apoptosis via the IRE1/caspase-12/caspase-3 pathway by modulating CALR ubiquitination. This study provides a theoretical basis for exploring the mechanisms of neurobrucellosis and offers insights into its clinical treatment.IMPORTANCENeurobrucellosis is a severe complication impacting the central nervous system (CNS) due to neurological deficits caused by Brucella, with primary clinical features including meningitis, encephalitis, brain abscesses, and demyelinating lesions. These nonspecific symptoms often lead to misdiagnosis or delayed diagnosis, increasing the risk of recurrent or chronic neurobrucellosis infections. Consequently, persistent infection and relapse are critical challenges in the clinical management of neurobrucellosis, which are closely linked to Brucella's survival and replication within microglia. Interestingly, Brucella may inhibit microglia apoptosis by mitigating endoplasmic reticulum (ER) stress, though the precise molecular mechanisms remain largely unexplored. Thus, this study will elucidate the specific mechanisms by which Brucella suppresses microglial apoptosis and provide deeper insights into the molecular pathogenesis and clinical treatment of neurobrucellosis.

Identification of E3 ubiquitin ligase-based molecular subtypes and prognostic signature regarding prognosis and immune landscape in bladder cancer

E3 ubiquitin ligases are acknowledged as the principal catalysts in the ubiquitination process due to their capacity to identify, bind and recruit specific substrates for modification. However, knowledge about the expression patterns of E3 ligases and their contribution to the tumor heterogeneity of bladder cancer (BLCA) is still lacking. Here, we delineated two distinct subcategories of BLCA utilizing consensus clustering of variable expression patterns of E3 ligases from the TCGA database, outlining the functional characteristics and immune profiles of these subclusters. Crucially, these clusters offered valuable perspectives on the tumor immune microenvironment (TIME) and tumor response to immunotherapy. Additionally, we established and validated an E3 ligase-related prognostic model predicated on genes associated with E3 ligases, which robustly foretold the prognosis, TIME, and the efficacy of immunotherapy in BLCA patients. Besides, we systematically interrogated the correlation between the IC50 values of commonly used antitumor drugs and the E3 ligase-related risk score and expression levels of prognostic genes. Notably, we identified and validated that EMP1 inhibition synergized with the antitumor effects of oxaliplatin in T24 and 5637 BLCA cell lines. Furthermore, knockdown of SLC26A8, an E3 ligase-related prognostic gene, significantly promoted tumor progression in BLCA. In summary, we introduced an innovative E3 ligase-based classification framework and prognostic model for BLCA, presenting a potent and auspicious prognostic and immunotherapeutic benefit predictor for individual BLCA patients.

Escherichia coli HPI-induced duodenitis through ubiquitin regulation of the TLR4/NF-κB pathway

BACKGROUND

The Highly Pathogenic Island (HPI) found in Yersinia pestis can be horizontally transferred to E. coli, enhancing its virulence and pathogenicity. Ubiquitin (Ub) acts as an activator of the NF-κB pathway and plays a critical role in the inflammatory response. However, the precise mechanism by which Ub and the regulated TLR4/NF-κB pathway contribute to HPI-induced intestinal inflammation in E. coli remains unclear.

RESULTS

In this study, we established Ub overexpression models of small intestinal epithelial cells (in vitro) and BALB/c mice (in vivo) and infected these models with HPI-rich E. coli. We investigated the role of the Ub-regulated TLR4/NF-κB pathway in E. coli HPI-induced intestinal inflammation through qPCR, ELISA, immunofluorescence, immunohistochemistry, and H&E staining. Our findings confirmed that E. coli HPI promoted the expression of Ub, TLR4, and NF-κB in IPEC-J2 cells and induced the translocation of NF-κB p65 protein to the nucleus. Further investigations revealed that Ub overexpression enhanced epithelial cell damage induced by E. coli HPI. This was accompanied by up-regulation of mRNA levels of TLR4, MyD88, NF-κB, IL-1β, and TNF-α, as well as increased release of the inflammatory factors IL-1β and TNF-α. In a mouse model with Ub overexpression infected with E. coli HPI, we observed that Ub overexpression promoted E. coli HPI-induced intestinal inflammation. Mechanistically, E. coli HPI induced intestinal epithelial cell damage by inducing Ub overexpression and modulating the TLR4/NF-κB pathway.

CONCLUSIONS

In conclusion, this study sheds light on the significant role of the Ub-regulated TLR4/NF-κB pathway in E. coli HPI-induced duodenitis, offering novel insights into the pathogenesis of E. coli infections.

UBE2T/CDC42/CD276 signaling axis mediates brain metastasis of triple-negative breast cancer via lysosomal autophagy

BACKGROUND

Advanced triple-negative breast cancer (TNBC) is prone to brain metastasis (BrM). The precise molecular mechanism responsible for this phenomenon has not yet been completely established, so it is vital to comprehend the molecular mechanism behind it.

METHODS

The protein chip analysis was conducted to identify any abnormal UBE2T protein expression in TNBC, especially BrM. Here, we used public databases and bioinformatics analysis as well as clinical samples from different cohorts to investigate the interrelationship between UBE2T/CDC42/CD276. This predicted relationship was then repeatedly validated using different in vivo and in vitro experimental methods. Additionally, multiple experimental approaches were implemented, encompassing western blotting, Co-IP, GST pull-down, flow cytometry, mass spectrometry, immunofluorescence, immunohistochemistry, and qRT-PCR to reveal the molecular mechanism of UBE2T-mediated immune escape and BrM.

RESULTS

Our results indicate that expressed at elevated levels in breast cancer, UBE2T is negatively linked to patient prognosis, especially in BrM of TNBC. Data from clinical samples from our different cohorts and TCGA indicate a significant correlation between UBE2T and immunosuppression. Mechanistically, UBE2T directly interacts with CDC42, promoting its K48-linked polyubiquitination and proteasomal degradation, thereby inhibiting CDC42 from degrading CD276 via the autophagy-lysosomal pathway, indirectly upregulating CD276 and thereby impairing the CD8+ T cells function, ultimately mediating tumor immune escape and BrM. Finally, animal experimental results also showed that inhibition of UBE2T elevated the TNBC sensitivity to immune checkpoint CD276 blockade and inhibited BrM of TNBC.

CONCLUSIONS

In conclusion, our results indicate a new mechanism whereby UBE2T-mediated ubiquitination positively controls the UBE2T/CDC42/CD276 axis to upregulate tumor cell expression of CD276 and thereby impair CD8+ T cells function, ultimately leading to tumor cell immune escape and BrM.

Context specific ubiquitin modification of ribosomes regulates translation under oxidative stress

Cellular exposure to stress is known to activate several translational control pathways through ribosome ubiquitination. However, how unique patterns of ribosome ubiquitination act at the site-specific level to drive distinct modes of translation regulation remains unclear. To further understand the complexity of these ubiquitin signals, we developed a new targeted proteomics approach to quantify site-specific ubiquitin modification across the ribosome. This method increased the sensitivity and throughput of current approaches and allowed us to systematically measure the ubiquitin status of 78 ribosome peptides and ubiquitin linkages in response to stress. Using this method, we were able to detect the ubiquitination of several ribosome sites even in steady-state conditions, and to show that their modification increases non-stoichiometrically in a dynamic range of >4 orders of magnitude in response to hydrogen peroxide. Besides demonstrating new patterns of global ribosome ubiquitination, our study also revealed an unexpected increase of ubiquitination of ribosomal protein uS10/Rps20 and uS3/Rps3 independent of the canonical E3 ubiquitin ligase Hel2. Furthermore, we show that unique and mixed patterns of ribosome ubiquitination occur in a stress specific manner, depending on the nature of stressor and the enzymes involved. Finally, we showed that while deletion of HEL2 further induces the integrated stress response in response to the nucleotide alkylating agent 4-NQO, deletion of the E2 conjugase RAD6 leads to sustained translation only in response to H2O2. Our findings contribute to deciphering the complexity of the stress response at the translational level, revealing the induction of dynamic and selective ubiquitin codes, which shed light on the integration of important quality control pathways during cellular response to stress.

Upregulation of olfactory receptors and neuronal-associated genes highlights complex immune and neuronal dysregulation in Long COVID patients

A substantial portion of patients infected with SARS-CoV-2 experience prolonged complications, known as Long COVID (LC). A subset of these patients exhibits the most debilitating symptoms, similar to those defined in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). We performed bulk RNA sequencing (RNAseq) on the whole blood of LC with ME/CFS, at least 12 months post-onset of the acute disease, and compared them with controls. We found that LC patients had a distinct transcriptional profile compared to controls. Key findings include the upregulation of genes involved in immune dysregulation and neuronal development, such as Fezf2, BRINP2, HOXC12, MEIS2, ZFHX3, and RELN. These genes are linked to neuroinflammatory responses, cognitive impairments, and hematopoietic disturbances, suggesting ongoing neurological and immune disturbances in LC patients. RELN, encoding the Reelin protein, was notably elevated in LC patients, potentially serving as a biomarker for LC pathogenesis due to its role in inflammation and neuronal function. Immune cell analysis showed altered profiles in LC patients, with increased activated memory CD4 + T cells and neutrophils, and decreased regulatory T cells and NK cells, reflecting immune dysregulation. Changes in cytokine and chemokine expression further underscore the chronic inflammatory state in LC patients. Notably, a unique upregulation of olfactory receptors (ORs) suggest alternative roles for ORs in non-olfactory tissues. Pathway analysis revealed upregulation in ribosomal RNA processing, amino acid metabolism, protein synthesis, cell proliferation, DNA repair, and mitochondrial pathways, indicating heightened metabolic and immune demands. Conversely, downregulated pathways, such as VEGF signaling and TP53 activity, point to impaired tissue repair and cellular stress responses. Overall, our study underscores the complex interplay between immune and neuronal dysfunction in LC patients, providing insights into potential diagnostic biomarkers and therapeutic targets. Future research is needed to fully understand the roles and interactions of these genes in LC pathophysiology.

Nanomaterials exert biological effects by influencing the ubiquitin-proteasome system

The ubiquitin-proteasome system (UPS) is an important type of protein post-translational modification that affects the quantity and quality of various proteins and influences cellular processes such as the cell cycle, transcription, oxidative stress, and autophagy. Nanomaterials (NMs), which exhibit excellent physicochemical properties, can directly interact with the UPS and act as molecular-targeted drugs to induce changes in biological processes. This review provides an overview of the influence of NMs on the UPS of misfolded proteins and key proteins, which are related to cancer, neurodegenerative diseases and oxidative stress. This review also summarizes the role of modification processes involved in ubiquitination the biological effects of NMs and the mechanism of such effects of NMs through regulation of the UPS. This review deepens our understanding of the influence of NMs on the protein degradation process and provides new potential therapeutic targets for disease.

TGM2-mediated histone serotonylation promotes HCC progression via MYC signalling pathway

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is an aggressive malignancy for which there are few effective treatment options. H3Q5ser, a serotonin-based histone modification mediated by transglutaminase 2 (TGM2), affects diverse biological processes, such as neurodevelopment. The role of TGM2-mediated H3Q5ser in HCC progression remains unclear. This study investigated the role of TGM2 in promoting HCC progression and evaluated its potential as a therapeutic target for HCC treatment.

METHODS

Adeno-associated virus-mediated liver-specific overexpression models of Tgm2 or H3.3 were adopted to validate the effects of H3Q5ser on HCC progression. CUT&Tag and RNA sequencing was employed to investigate the underlying mechanisms. HCC organoids, subcutaneous xenograft models, and hydrodynamic tail vein injection models were used to evaluate the treatment efficiency of TGM2 inhibitors.

RESULTS

TMG2 expression positively correlated with higher alpha-fetoprotein levels, poor differentiation, and a later BCLC stage. Tgm2 deficiency or H3Q5ser inhibition notably inhibited HCC progression. CUT&Tag and RNA sequencing analyses revealed that downregulated genes were enriched in the MYC pathway following treatment with the TGM2 inhibitors. Furthermore, transcriptional intermediary factor 1 β mediated the recruitment of TGM2 to MYC, facilitating H3Q5ser modifications on MYC target genes. Finally, targeting the transglutaminase activity of TGM2 significantly suppressed HCC progression and showed synergy with sorafenib treatment in preclinical models. TGM2 inhibitors did not cause significant myelosuppression or tissue damage.

CONCLUSIONS

TGM2 serves as a prognostic biomarker and targeting its transglutaminase activity may be an effective strategy for inhibiting HCC progression.

IMPACT AND IMPLICATIONS

Transglutaminase 2 (TGM2)-mediated H3Q5ser modifications promote hepatocellular carcinoma (HCC) progression via MYC pathway signalling. Targeting the transglutaminase activity of TGM2 markedly inhibited HCC progression. TGM2 inhibitors did not induce significant myelosuppression or tissue damage. This preclinical study provides a theoretical basis to explore new strategies for HCC therapy.

Leveraging single-cell and multi-omics approaches to identify MTOR-centered deubiquitination signatures in esophageal cancer therapy

Background

Esophageal squamous cell carcinoma (ESCC) remains a significant challenge in oncology due to its aggressive nature and heterogeneity. As one of the deadliest malignancies, ESCC research lags behind other cancer types. The balance between ubiquitination and deubiquitination processes plays a crucial role in cellular functions, with its disruption linked to various diseases, including cancer.

Methods

Our study utilized diverse analytical approaches, encompassing Cox regression models, single-cell RNA sequencing, intercellular communication analysis, and Gene Ontology enrichment. We also conducted mutation profiling and explored potential immunotherapeutic agents. Furthermore, in vitro cellular experiments and in vivo mouse models were performed to validate findings. These methodologies aimed to establish deubiquitination-related gene signatures (DRGS) for predicting ESCC patient outcomes and response to immunotherapy.

Results

By integrating datasets from TCGA-ESCC and GSE53624, we developed a DRGS model based on 14 deubiquitination-related genes (DUBGs). This signature effectively forecasts ESCC prognosis, drug responsiveness, and immune cell infiltration patterns. It also influences the mutational landscape of patients. Those classified as high-risk exhibited reduced survival rates, increased genetic alterations, and more complex cellular interactions, potentially explaining their poor outcomes. Notably, in vitro and in vivo experiments identified MTOR, a key component of the signature, as a promising therapeutic target for ESCC treatment.

Conclusion

Our research highlights the significance of 14 DUBGs in ESCC progression. The risk score derived from this gene set enables clinical stratification of patients into distinct prognostic groups. Moreover, MTOR emerges as a potential target for personalized ESCC therapy, offering new avenues for treatment strategies.

Proteomic identification of potential biomarkers for heat tolerance in Caracu beef cattle using high and low thermotolerant groups

BACKGROUND

Heat stress has deleterious effects on physiological and performance traits in livestock. Within this context, using tropically adapted cattle breeds in pure herds or terminal crossbreeding schemes to explore heterosis is attractive for increasing animal production in warmer climate regions. This study aimed to identify biological processes, pathways, and potential biomarkers related to thermotolerance in Caracu, a tropically adapted beef cattle breed, by proteomic analysis of blood plasma. To achieve this goal, 61 bulls had their thermotolerance evaluated through a heat tolerance index. A subset of 14 extreme animals, including the seven most thermotolerant (HIGH group) and the seven least thermotolerant (LOW group), had their blood plasma samples used for proteomic analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The differentially regulated proteins detected between HIGH and LOW groups were used to perform functional enrichment analysis and a protein-protein interaction network analysis.

RESULTS

A total of 217 proteins were detected only in the HIGH thermotolerant group and 51 only in the LOW thermotolerant group. In addition, 81 and 87 proteins had significantly higher and lower abundancies in the HIGH group, respectively. Regarding proteins with the highest absolute log-fold change values, we highlighted those encoded by DUSP5, IGFALS, ROCK2, RTN4, IRAG1, and NNT genes based on their functions. The functional enrichment analysis detected several biological processes, molecular functions, and pathways related to cellular responses to stress, immune system, complement system, and hemostasis in both HIGH and LOW groups, in addition to terms and pathways related to lipids and calcium only in the HIGH group. Protein-protein interaction (PPI) network revealed as important nodes many proteins with roles in response to stress, hemostasis, immune system, inflammation, and homeostasis. Additionally, proteins with high absolute log-fold change values and proteins detected as essential nodes by PPI analysis highlighted herein are potential biomarkers for thermotolerance, such as ADRA1A, APOA1, APOB, APOC3, C4BPA, CAT, CFB, CFH, CLU, CXADR, DNAJB1, DNAJC13, DUSP5, FGA, FGB, FGG, HBA, HBB, HP, HSPD1, IGFALS, IRAG1, KNG1, NNT, OSGIN1, PROC, PROS1, ROCK2, RTN4, RYR1, TGFB2, VLDLR, VTN, and VWF.

CONCLUSIONS

Identifying potential biomarkers, molecular mechanisms and pathways that act in response to heat stress in tropically adapted beef cattle contributes to developing strategies to improve performance and welfare traits in livestock under tropical climates.

USP15 regulates radiation-induced DNA damage and intestinal injury through K48-linked deubiquitination and stabilisation of ATM

BACKGROUND

Radiation-induced intestinal injury (RIII) interrupts the scheduled processes of abdominal and pelvic radiotherapy (RT) and compromises the quality of life of cancer survivors. However, the specific regulators and mechanisms underlying the effects of RIII remain unknown. The biological effects of RT are caused primarily by DNA damage, and ataxia telangiectasia mutated (ATM) is a core protein of the DNA damage response (DDR). However, whether ATM is regulated by deubiquitination signaling remains unclear.

METHODS

We established animal and cellular models of RIII. The effects of ubiquitin-specific protease 15 (USP15) on DNA damage and radion-induced intestinal injury were evaluated. Mass spectrometry analysis, truncation tests, and immunoprecipitation were used to identify USP15 as a binding partner of ATM and to investigate the ubiquitination of ATM. Finally, the relationship between the USP15/ATM axes was further determined via subsequent experiments.

RESULTS

In this study, we identified the deubiquitylating enzyme USP15 as a regulator of DNA damage and the pathological progression of RIII. Irradiation upregulates the expression of USP15, whereas pharmacological inhibition of USP15 exacerbates radiation-induced DNA damage and RIII both in vivo and in vitro. Mechanistically, USP15 interacts with, deubiquitinates, and stabilises ATM via K48-linked deubiquitination. Notably, ATM overexpression blocks the effect of USP15 genetic inhibition on DNA damage and RIII progression.

CONCLUSIONS

These findings describe ATM as a novel deubiquitination target of USP15 upon radiation-induced DNA damage and intestinal injury, and provides experimental support for USP15/ATM axis as a potential target for developing strategies that mitigate RIII.

E3 ubiquitin ligase ANKIB1 attenuates antiviral immune responses by promoting K48-linked polyubiquitination of MAVS

Upon sensing cytosolic viral RNA, retinoic acid-inducible gene-I-like receptors (RLRs) interact with mitochondrial antiviral signaling proteins (MAVSs) to activate IRF3 and nuclear factor κB (NF-κB) signaling, initiating innate immune responses. Thus, RLR activation plays a vital role in the removal of invasive RNA viruses while maintaining immune homeostasis. However, inadequate or excessive activation of immunity can cause harm and can even lead to lethal consequences. In this study, we identify an E3 ligase, ankyrin repeat and IBR domain containing 1 (ANKIB1), which suppresses RLR signaling via MAVS. ANKIB1 binds to MAVS to enhance K48-linked polyubiquitination with K311R, causing proteasomal degradation of MAVS. Deficiency of ANKIB1 significantly increases the RLR-mediated production of type I interferon (IFN) along with pro-inflammatory factors. Consequently, ANKIB1 deficiency remarkably increases antiviral immunity and decreases viral replication in vivo. Therefore, we reveal that ANKIB1 restricts RLR-induced innate immune activation, indicating its potential role as a therapeutic target for viral infections.

TRIM59 is required for mouse GC-1 cell maintenance through modulating the ubiquitination of AXIN1

Tripartite motif-containing protein 59 (TRIM59) is a biomarker for multiple tumors with crucial roles. However, the specific role of TRIM59 in germ cells remains largely unknown. Here, we investigated the effects and underlying regulatory mechanisms of TRIM59 on germ cells using the mouse spermatogonial cell line GC-1. Our results demonstrated that TRIM59 promoted proliferation and inhibited apoptosis of GC-1 cells. Mechanistically, TRIM59 maintained GC-1 cell behaviors through ubiquitination of AXIN1 to activate β-catenin signaling. Furthermore, activation of β-catenin signaling reversed the effects mediated by Trim59 knockdown in GC-1 cells. Collectively, our study revealed a major role and regulatory mechanism of TRIM59 in GC-1 cells, which sheds new light on the molecular pathogenesis of defects in spermatogenesis and may provide therapeutic targets for treatment of male infertility.

Cellular Stress in Dry Eye Disease-Key Hub of the Vicious Circle

Disturbance or insufficiency of the tear film challenges the regulatory systems of the ocular surfaces. The reaction of the surfaces includes temporary mechanisms engaged in the preservation of homeostasis. However, strong or persisting challenges can lead to the potential exhaustion of the coping capacity. This again activates the vicious circle with chronic inflammation and autocatalytic deterioration. Hence, the factors challenging the homeostasis should be addressed in time. Amongst them are a varying osmolarity, constant presence of small lesions at the epithelium, acidification, attrition with mechanical irritation, and onset of pain and discomfort. Each of them and, especially when occurring simultaneously, impose stress on the coping mechanisms and lead to a stress response. Many stressors can culminate, leading to an exhaustion of the coping capacity, outrunning normal resilience. Reaching the limits of stress tolerance leads to the manifestation of a lubrication deficiency as the disease we refer to as dry eye disease (DED). To postpone its manifestation, the avoidance or amelioration of stress factors is one key option. In DED, this is the target of lubrication therapy, substituting the missing tear film or its components. The latter options include the management of secondary sequelae such as the inflammation and activation of reparative cascades. Preventive measures include the enhancement in resilience, recovery velocity, and recovery potential. The capacity to handle the external load factors is the key issue. The aim is to guard homeostasis and to prevent intercellular stress responses from being launched, triggering and invigorating the vicious circle. Considering the dilemma of the surface to have to cope with increased time of exposure to stress, with simultaneously decreasing time for cellular recovery, it illustrates the importance of the vicious circle as a hub for ocular surface stress. The resulting imbalance triggers a continuous deterioration of the ocular surface condition. After an initial phase of the reaction and adaption of the ocular surface to the surrounding challenges, the normal coping capacity will be exhausted. This is the time when the integrated stress response (ISR), a protector for cellular survival, will inevitably be activated, and cellular changes such as altered translation and ribosome pausing are initiated. Once activated, this will slow down any recovery, in a phase where apoptosis is imminent. Premature senescence of cells may also occur. The process of prematurization due to permanent stress exposures contributes to the risk for constant deterioration. The illustrated flow of events in the development of DED outlines that the ability to cope, and to recover, has limited resources in the cells at the ocular surface. The reduction in and amelioration of stress hence should be one of the key targets of therapy and begin early. Here, lubrication optimization as well as causal treatment such as the correction of anatomical anomalies (leading to anatomical dry eye) should be a prime intent of any therapy. The features of cellular stress as a key hub for the vicious circle will be outlined and discussed.

Comparative RNA-Seq of Ten Phaeodactylum tricornutum Accessions: Unravelling Criteria for Robust Strain Selection from a Bioproduction Point of View

The production of biologics in mammalian cells is hindered by some limitations including high production costs, prompting the exploration of other alternative expression systems that are cheaper and sustainable like microalgae. Successful productions of biologics such as monoclonal antibodies have already been demonstrated in the diatom Phaeodactylum tricornutum; however, limited production yields still remain compared to mammalian cells. Therefore, efforts are needed to make this microalga more competitive as a cell biofactory. Among the seventeen reported accessions of P. tricornutum, ten have been mainly studied so far. Among them, some have already been used to produce high-value-added molecules such as biologics. The use of "omics" is increasingly being described as useful for the improvement of both upstream and downstream steps in bioprocesses using mammalian cells. Therefore, in this context, we performed an RNA-Seq analysis of the ten most used P. tricornutum accessions (Pt1 to Pt10) and deciphered the differential gene expression in pathways that could affect bioproduction of biologics in P. tricornutum. Our results highlighted the benefits of certain accessions such as Pt9 or Pt4 for the production of biologics. Indeed, these accessions seem to be more advantageous. Moreover, these results contribute to a better understanding of the molecular and cellular biology of P. tricornutum.

The HRD1-SEL1L ubiquitin ligase regulates stress granule homeostasis in couple with distinctive signaling branches of ER stress

Stress granules (SGs) are membrane-less cellular compartments which are dynamically assembled via biomolecular condensation mechanism when eukaryotic cells encounter environmental stresses. SGs are important for gene expression and cell fate regulation. Dysregulation of SG homeostasis has been linked to human neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here we report that the HRD1-SEL1L ubiquitin ligase complex specifically regulates the homeostasis of heat shock-induced SGs through the ubiquitin-proteasome system (UPS) and the UPS-associated ATPase p97. Mechanistically, the HRD1-SEL1L complex mediates SG homeostasis through the BiP-coupled PERK-eIF2α signaling axis of endoplasmic reticulum (ER) stress, thereby coordinating the unfolded protein response (UPR) with SG dynamics. Furthermore, we show that the distinctive branches of ER stress play differential roles in SG homeostasis. Our study indicates that the UPS and the UPR together via the HRD1-SEL1L ubiquitin ligase to maintain SG homeostasis in a stressor-dependent manner.

Using protein turnover assay to explore the drug mechanism of Carfilzomib

Carfilzomib (CFZ) is the second-generation proteasome inhibitor that is approved by Food and Drug Administration (FDA) of USA for the treatment of relapsed and refractory multiple myeloma. Although the preclinical and clinical efficacy of CFZ is obvious, the mechanism by which CFZ leads to cell death has not been fully elucidated. Since CFZ primarily functions as a proteasome inhibitor, profiling CFZ-induced changes in protein turnover at the systematic level is sufficient and necessary. In this study, we characterize the effects of CFZ on the stability of 15,000 human proteins using Protein Turnover Assay (ProTA). CFZ affects fundamental cellular glycolysis, nitric oxide production and proteasome subunit homeostasis in multiple myeloma cells. In addition, LY294002 or KU-0063794 has synergistic effects with CFZ in multiple myeloma treatment. A profound understanding of how cells respond to chemotherapeutic agents provides insights into the basic mechanism of drug function and the rationale for CFZ combination therapy.

Entire expressed peripheral blood transcriptome in pediatric severe malarial anemia

This study on severe malarial anemia (SMA: Hb < 6.0 g/dL), a leading global cause of childhood morbidity and mortality, compares the entire expressed whole blood host transcriptome between Kenyan children (3-48 mos.) with non-SMA (Hb ≥ 6.0 g/dL, n = 39) and SMA (n = 18). Differential expression analyses reveal 1403 up-regulated and 279 down-regulated transcripts in SMA, signifying impairments in host inflammasome activation, cell death, and innate immune and cellular stress responses. Immune cell profiling shows decreased memory responses, antigen presentation, and immediate pathogen clearance, suggesting an immature/improperly regulated immune response in SMA. Module repertoire analysis of blood-specific gene signatures identifies up-regulation of erythroid genes, enhanced neutrophil activation, and impaired inflammatory responses in SMA. Enrichment analyses converge on disruptions in cellular homeostasis and regulatory pathways for the ubiquitin-proteasome system, autophagy, and heme metabolism. Pathway analyses highlight activation in response to hypoxic conditions [Hypoxia Inducible Factor (HIF)-1 target and Reactive Oxygen Species (ROS) signaling] as a central theme in SMA. These signaling pathways are also top-ranking in protein abundance measures and a Ugandan SMA cohort with available transcriptomic data. Targeted RNA-Seq validation shows strong concordance with our entire expressed transcriptome data. These findings identify key molecular themes in SMA pathogenesis, offering potential targets for new malaria therapies.

Enhanced translocation of TRIM32 to mitochondria sensitizes dopaminergic neuronal cells to apoptosis during stress conditions in Parkinson's disease

Parkinson's disease (PD) is a chronic neurodegenerative disease characterized by progressive loss of dopamine-producing neurons from the substantia nigra region of the brain. Mitochondrial dysfunction is one of the major causes of oxidative stress and neuronal cell death in PD. E3 ubiquitin ligases such as Parkin (PRKN) modulate mitochondrial quality control in PD; however, the role of other E3 ligases associated with mitochondria in the regulation of neuronal cell death in PD has not been explored. The current study investigated the role of TRIM32, RING E3 ligase, in sensitization to oxidative stress-induced neuronal apoptosis. The expression of TRIM32 sensitizes SH-SY5Y dopaminergic cells to rotenone and 6-OHDA-induced neuronal death, whereas the knockdown increased cell viability under PD stress conditions. The turnover of TRIM32 is enhanced under PD stress conditions and is mediated by autophagy. TRIM32 translocation to mitochondria is enhanced under PD stress conditions and localizes on the outer mitochondrial membrane. TRIM32 decreases complex-I assembly and activity as well as mitochondrial reactive oxygen species (ROS) and ATP levels under PD stress. Deletion of the RING domain of TRIM32 enhanced complex I activity and rescued ROS levels and neuronal viability under PD stress conditions. TRIM32 decreases the level of XIAP, and co-expression of XIAP with TRIM32 rescued the PD stress-induced cell death and mitochondrial ROS level. In conclusion, turnover of TRIM32 increases during stress conditions and translocation to mitochondria is enhanced, regulating mitochondrial functions and neuronal apoptosis by modulating the level of XIAP in PD.

Ubiquitous regulation of cerebrovascular diseases by ubiquitin-modifying enzymes

Cerebrovascular diseases (CVDs) are a major threat to global health. Elucidation of the molecular mechanisms underlying the pathology of CVDs is critical for the development of efficacious preventative and therapeutic approaches. Accumulating studies have highlighted the significance of ubiquitin-modifying enzymes (UMEs) in the regulation of CVDs. UMEs are a group of enzymes that orchestrate ubiquitination, a post-translational modification tightly involved in CVDs. Functionally, UMEs regulate multiple pathological processes in ischemic and hemorrhagic stroke, moyamoya disease, and atherosclerosis. Considering the important roles of UMEs in CVDs, they may become novel druggable targets for these diseases. Besides, techniques applying UMEs, such as proteolysis-targeting chimera and deubiquitinase-targeting chimera, may also revolutionize the therapy of CVDs in the future.

Magnolol promotes the autophagy of esophageal carcinoma cells by upregulating HACE1 gene expression

Esophagus cancer (EC) is one of the most aggressive malignant digestive system tumors and has a high clinical incidence worldwide. Magnolol, a natural compound, has anticancer effects on many cancers, including esophageal carcinoma, but the underlying mechanism has not been fully elucidated. Here, we first find that magnolol inhibits the proliferation of esophageal carcinoma cells and enhances their autophagy activity in a dose- and time-dependent manner. This study demonstrates that magnolol increases the protein levels of LC3 II, accompanied by increased HACE1 protein levels in both esophageal carcinoma cells and xenograft tumors. HACE1-knockout (KO) cell lines are generated, and the ablation of HACE1 eliminates the anti-proliferative and autophagy-inducing effects of magnolol on esophageal carcinoma cells. Additionally, our results show that magnolol primarily promotes HACE1 expression at the transcriptional level. Therefore, this study shows that magnolol primarily exerts its antitumor effect by activating HACE1-OPTN axis-mediated autophagy. It can be considered a promising therapeutic drug for esophageal carcinoma.

Non-proteolytic ubiquitination of HBx controls HBV replication

•The expression level of TRIM21 in patients is negatively correlated with the replication and integration of HBV. •TRIM21 was found to trigger non-proteolytic ubiquitination of X protein of HBV. •This study proposes that the PRYSPRY and RING domains in TRIM21 dimer can form a docking conformation for HBx binding. •TRIM21-mediated HBx ubiquitination disrupts the DDB1 recruitment to HBx and stabilize Smc6.

Advances in secondary prevention mechanisms of macrovascular complications in type 2 diabetes mellitus patients: a comprehensive review

Type 2 diabetes mellitus (T2DM) poses a significant global health burden. This is particularly due to its macrovascular complications, such as coronary artery disease, peripheral vascular disease, and cerebrovascular disease, which have emerged as leading contributors to morbidity and mortality. This review comprehensively explores the pathophysiological mechanisms underlying these complications, protective strategies, and both existing and emerging secondary preventive measures. Furthermore, we delve into the applications of experimental models and methodologies in foundational research while also highlighting current research limitations and future directions. Specifically, we focus on the literature published post-2020 concerning the secondary prevention of macrovascular complications in patients with T2DM by conducting a targeted review of studies supported by robust evidence to offer a holistic perspective.

RNF125‑mediated ubiquitination of MCM6 regulates the proliferation of human liver hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-associated mortality worldwide. Minichromosome maintenance proteins (MCMs), particularly MCM2-7, are upregulated in various cancers, including HCC. The aim of the present study was to investigate the role of MCM2-7 in human liver HCC (LIHC) and the regulation of the protein homeostasis of MCM6 by a specific E3 ligase. Bioinformatics analyses demonstrated that MCM2-7 were highly expressed in LIHC compared with corresponding normal tissues at the mRNA and protein levels, and patients with LIHC and high mRNA expression levels of MCM2, MCM3, MCM6 and MCM7 had poor overall survival rates. Cell Counting Kit-8 and colony formation assays revealed that the knockdown of MCM2, MCM3, MCM6 or MCM7 in Huh7 and Hep3B HCC cells inhibited cell proliferation and colony formation. In addition, pull-down, co-immunoprecipitation and ubiquitination assays demonstrated that RNF125 interacts with MCM6 and mediates its ubiquitination. Furthermore, co-transfection experiments indicated that RNF125 promoted the proliferation of HCC cells mainly through MCM6. In summary, the present study suggests that the RNF125-MCM6 axis plays an important role in the regulation of HCC cell proliferation and is a promising therapeutic target for the treatment of LIHC.

The E3 ubiquitin ligase MARCH2 protects against myocardial ischemia-reperfusion injury through inhibiting pyroptosis via negative regulation of PGAM5/MAVS/NLRP3 axis

Inflammasome activation and pyroptotic cell death are known to contribute to the pathogenesis of cardiovascular diseases, such as myocardial ischemia-reperfusion (I/R) injury, although the underlying regulatory mechanisms remain poorly understood. Here we report that expression levels of the E3 ubiquitin ligase membrane-associated RING finger protein 2 (MARCH2) were elevated in ischemic human hearts or mouse hearts upon I/R injury. Genetic ablation of MARCH2 aggravated myocardial infarction and cardiac dysfunction upon myocardial I/R injury. Single-cell RNA-seq analysis suggested that loss of MARCH2 prompted activation of NLRP3 inflammasome in cardiomyocytes. Mechanistically, phosphoglycerate mutase 5 (PGAM5) was found to act as a novel regulator of MAVS-NLRP3 signaling by forming liquid-liquid phase separation condensates with MAVS and fostering the recruitment of NLRP3. MARCH2 directly interacts with PGAM5 to promote its K48-linked polyubiquitination and proteasomal degradation, resulting in reduced PGAM5-MAVS co-condensation, and consequently inhibition of NLRP3 inflammasome activation and cardiomyocyte pyroptosis. AAV-based re-introduction of MARCH2 significantly ameliorated I/R-induced mouse heart dysfunction. Altogether, our findings reveal a novel mechanism where MARCH2-mediated ubiquitination negatively regulates the PGAM5/MAVS/NLRP3 axis to protect against cardiomyocyte pyroptosis and myocardial I/R injury.