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Transcription-blocking lesions (TBLs) stall elongating RNA polymerase II (Pol II), which then initiates transcription-coupled repair (TCR) to remove TBLs and allow transcription recovery. In the absence of TCR, eviction of lesion-stalled Pol II is required for alternative pathways to address the damage, but the mechanism is unclear. Using Protein-Associated DNA Damage Sequencing (PADD-seq), this study reveals that the p97-proteasome pathway can evict lesion-stalled Pol II independently of repair. Both TCR and repair-independent eviction require CSA and ubiquitination. However, p97 is dispensable for TCR and Pol II eviction in TCR-proficient cells, highlighting repairs prioritization over repair-independent eviction. Moreover, ubiquitination of RPB1-K1268 is important for both pathways, with USP7s deubiquitinase activity promoting TCR without abolishing repair-independent Pol II release. In summary, this study elucidates the fate of lesion-stalled Pol II, and may shed light on the molecular basis of genetic diseases caused by the defects of TCR genes.

Isoform 1 of DNA methyltransferase DNMT3A (DNMT3A1) specifically recognizes nucleosome monoubiquitylated at histone H2A lysine-119 (H2AK119ub1) for establishment of DNA methylation. Mis-regulation of this process may cause aberrant DNA methylation and pathogenesis. However, the molecular basis underlying DNMT3A1-nucleosome interaction remains elusive. Here we report the cryo-EM structure of DNMT3A1s ubiquitin-dependent recruitment (UDR) fragment complexed with H2AK119ub1-modified nucleosome. DNMT3A1 UDR occupies an extensive nucleosome surface, involving the H2A-H2B acidic patch, a surface groove formed by H2A and H3, nucleosomal DNA, and H2AK119ub1. The DNMT3A1 UDRs interaction with H2AK119ub1 affects the functionality of DNMT3A1 in cells in a context-dependent manner. Our structural and biochemical analysis also reveals competition between DNMT3A1 and JARID2, a cofactor of polycomb repression complex 2 (PRC2), for nucleosome binding, suggesting the interplay between different epigenetic pathways. Together, this study reports a molecular basis for H2AK119ub1-dependent DNMT3A1-nucleosome association, with important implications in DNMT3A1-mediated DNA methylation in development.

The F-box domain is a highly conserved structural motif that defines the largest class of ubiquitin ligases, Skp1/Cullin1/F-box protein (SCF) complexes. The only known function of the F-box motif is to form the protein interaction surface with Skp1. Here we show that the F-box domain can function as an environmental sensor. We demonstrate that the F-box domain of Met30 is a cadmium sensor that blocks the activity of the SCFMet30 ubiquitin ligase during cadmium stress. Several highly conserved cysteine residues within the Met30 F-box contribute to binding of cadmium with a KD of 8 µM. Binding induces a conformational change that allows for Met30 autoubiquitylation, which in turn leads to recruitment of the segregase Cdc48/p97/VCP followed by active SCFMet30 disassembly. The resulting inactivation of SCFMet30 protects cells from cadmium stress. Our results show that F-box domains participate in regulation of SCF ligases beyond formation of the Skp1 binding interface.

Regular exercise promotes whole-body health and prevents disease, but the underlying molecular mechanisms are incompletely understood1-3. Here, the Molecular Transducers of Physical Activity Consortium4 profiled the temporal transcriptome, proteome, metabolome, lipidome, phosphoproteome, acetylproteome, ubiquitylproteome, epigenome and immunome in whole blood, plasma and 18 solid tissues in male and female Rattus norvegicus over eight weeks of endurance exercise training. The resulting data compendium encompasses 9,466 assays across 19 tissues, 25 molecular platforms and 4 training time points. Thousands of shared and tissue-specific molecular alterations were identified, with sex differences found in multiple tissues. Temporal multi-omic and multi-tissue analyses revealed expansive biological insights into the adaptive responses to endurance training, including widespread regulation of immune, metabolic, stress response and mitochondrial pathways. Many changes were relevant to human health, including non-alcoholic fatty liver disease, inflammatory bowel disease, cardiovascular health and tissue injury and recovery. The data and analyses presented in this study will serve as valuable resources for understanding and exploring the multi-tissue molecular effects of endurance training and are provided in a public repository ( https://motrpac-data.org/ ).

The intracellular bacterial pathogen Legionella pneumophila (L.p.) manipulates eukaryotic host ubiquitination machinery to form its replicative vacuole. While nearly 10% of L.p.'s ∼330 secreted effector proteins are ubiquitin ligases or deubiquitinases, a comprehensive measure of temporally resolved changes in the endogenous host ubiquitinome during infection has not been undertaken. To elucidate how L.p. hijacks host cell ubiquitin signaling, we generated a proteome-wide analysis of changes in protein ubiquitination during infection. We discover that L.p. infection increases ubiquitination of host regulators of subcellular trafficking and membrane dynamics, most notably ∼40% of mammalian Ras superfamily small GTPases. We determine that these small GTPases undergo nondegradative ubiquitination at the Legionella-containing vacuole (LCV) membrane. Finally, we find that the bacterial effectors SidC/SdcA play a central role in cross-family small GTPase ubiquitination, and that these effectors function upstream of SidE family ligases in the polyubiquitination and retention of GTPases in the LCV membrane. This work highlights the extensive reconfiguration of host ubiquitin signaling by bacterial effectors during infection and establishes simultaneous ubiquitination of small GTPases across the Ras superfamily as a novel consequence of L.p. infection. Our findings position L.p. as a tool to better understand how small GTPases can be regulated by ubiquitination in uninfected contexts.

Cells entrust ribosomes with the critical task of identifying problematic mRNAs and facilitating their degradation. Ribosomes must communicate when they encounter and stall on an aberrant mRNA, lest they expose the cell to toxic and disease-causing proteins, or they jeopardize ribosome homeostasis and cellular translation. In recent years, ribosomal ubiquitination has emerged as a central signaling step in this process, and proteomic studies across labs and experimental systems show a myriad of ubiquitination sites throughout the ribosome. Work from many labs zeroed in on ubiquitination in one region of the small ribosomal subunit as being functionally significant, with the balance and exact ubiquitination sites determined by stall type, E3 ubiquitin ligases, and deubiquitinases. This review discusses the current literature surrounding ribosomal ubiquitination during translational stress and considers its role in committing translational complexes to decay.

Stress response pathways detect and alleviate adverse conditions to safeguard cell and tissue homeostasis, yet their prolonged activation induces apoptosis and disrupts organismal health1-3. How stress responses are turned off at the right time and place remains poorly understood. Here we report a ubiquitin-dependent mechanism that silences the cellular response to mitochondrial protein import stress. Crucial to this process is the silencing factor of the integrated stress response (SIFI), a large E3 ligase complex mutated in ataxia and in early-onset dementia that degrades both unimported mitochondrial precursors and stress response components. By recognizing bifunctional substrate motifs that equally encode protein localization and stability, the SIFI complex turns off a general stress response after a specific stress event has been resolved. Pharmacological stress response silencing sustains cell survival even if stress resolution failed, which underscores the importance of signal termination and provides a roadmap for treating neurodegenerative diseases caused by mitochondrial import defects.

N-Myc is a key driver of neuroblastoma and neuroendocrine prostate cancer (NEPC). One potential way to circumvent the challenge of undruggable N-Myc is to target the protein homeostasis (proteostasis) system that maintains N-Myc levels. Here, we identify heat shock protein 70 (HSP70) as a top partner of N-Myc, which binds a conserved "SELILKR" motif and prevents the access of E3 ubiquitin ligase, STIP1 homology and U-box containing protein 1 (STUB1), possibly through steric hindrance. When HSP70's dwell time on N-Myc is increased by treatment with the HSP70 allosteric inhibitor, STUB1 is in close proximity with N-Myc and becomes functional to promote N-Myc ubiquitination on the K416 and K419 sites and forms polyubiquitination chains linked by the K11 and K63 sites. Notably, HSP70 inhibition significantly suppressed NEPC tumor growth, increased the efficacy of aurora kinase A (AURKA) inhibitors, and limited the expression of neuroendocrine-related pathways.

The master DNA damage repair histone protein, H2AX, is essential for orchestrating the recruitment of downstream mediator and effector proteins at damaged chromatin. The phosphorylation of H2AX at S139, γH2AX, is well-studied for its DNA repair function. However, the extended C-terminal tail is not characterized. Here, we define the minimal motif on H2AX for the canonical function in activating the MDC1-RNF8-RNF168 phosphorylation-ubiquitination pathway that is important for recruiting repair proteins, such as 53BP1 and BRCA1. Interestingly, H2AX recruits 53BP1 independently from the MDC1-RNF8-RNF168 pathway through its evolved C-terminal linker region with S139 phosphorylation. Mechanistically, 53BP1 recruitment to damaged chromatin is mediated by the interaction between the H2AX C-terminal tail and the 53BP1 Oligomerization-Tudor domains. Moreover, γH2AX-linker mediated 53BP1 recruitment leads to camptothecin resistance in H2AX knockout cells. Overall, our study uncovers an evolved mechanism within the H2AX C-terminal tail for regulating DNA repair proteins at damaged chromatin.

AIMP2-DX2 (hereafter DX2) is an oncogenic variant of aminoacyl-tRNA synthetase-interacting multifunctional protein 2 (AIMP2) that mediates tumorigenic interactions with various factors involved in cancer. Reducing the levels of DX2 can effectively inhibit tumorigenesis. We previously reported that DX2 can be degraded through Siah1-mediated ubiquitination. In this study, we identified a compound, SDL01, which enhanced the interaction between DX2 and Siah1, thereby facilitating the ubiquitin-dependent degradation of DX2. SDL01 was found to bind to the pocket surrounding the N -terminal flexible region and GST domain of DX2, causing a conformational change that stabilized its interaction with Siah1. Our findings demonstrate that protein-protein interactions (PPIs) can be modulated through chemically induced conformational changes. [Display omitted] • SDL01, an allosteric modulator and PPI stabilizer, promotes DX2 degradation by Siah1 • SDL01 induces conformational changes in DX2 to stabilize DX2-Siah1 interaction • SDL01 binds to DX2 at sites distant from the PPI interface • SDL01 decreases tumor growth in an in vivo model, demonstrating therapeutic potential Kim et al. discover SDL01, a compound that induces the degradation of DX2, an oncogenic protein. SDL01 promotes the interactions between DX2 and the proteins that mark it for degradation. This method highlights the therapeutic potential of small-molecular-weight regulators in cancer treatment by regulating protein-protein interactions. [ABSTRACT FROM AUTHOR]

Root hairs (RHs) are an innovation of vascular plants whose development is coordinated by endogenous and environmental cues, such as ethylene and light conditions. However, the potential crosstalk between ethylene and light conditions in RH development is unclear. We report that Arabidopsis constitutive photomorphogenic 1 (COP1) integrates ethylene and light signaling to mediate RH development. Darkness suppresses RH development largely through COP1. COP1 inhibits both cell fate determination of trichoblast and tip growth of RHs based on pharmacological, genetic, and physiological analyses. Indeed, COP1 interacts with and catalyzes the ubiquitination of ACS2 and ACS6. COP1- or darkness-promoted proteasome-dependent degradation of ACS2/6 leads to a low ethylene level in underground tissues. The negative role of COP1 in RH development by downregulating ethylene signaling may be coordinated with the positive role of COP1 in hypocotyl elongation by upregulating ethylene signaling, providing an evolutionary advantage for seedling fitness. [Display omitted] • Root hairs respond to light or ethylene by increasing both density and length • Arabidopsis COP1, the light responsive factor, inhibits root hair development • COP1 catalyzes the ubiquitination of type I ACSs to reduce ethylene responses • Dark-induced 26S-proteasome-mediated degradation of type I ACSs largely depends on COP1 Yin et al. report that Arabidopsis constitutive photomorphogenic 1 (COP1), a light response factor, controls root hair development by catalyzing the ubiquitination of type I ACSs and degradation to inhibit ethylene biosynthesis. The negative role of COP1 in root hairs may coordinate with its positive role in hypocotyl elongation to promote seedling fitness. [ABSTRACT FROM AUTHOR]

The tumor suppressor p53 plays a central role in suppressing tumor formation. Mouse double minute 2 homolog (Mdm2) serves as the principal ubiquitin E3 ligase responsible for the ubiquitination and subsequent degradation of p53. However, the regulatory mechanisms governing the Mdm2–p53 pathway are not comprehensively understood. Here, we report that F‐box only protein 46 (FBXO46) directly binds to Mdm2 and inhibits its self‐ubiquitination and degradation, leading to Mdm2 stabilization and subsequent Mdm2‐mediated ubiquitination and degradation of p53. Functionally, FBXO46 promotes cell proliferation, accelerates G1/S cell cycle progression, and increases anchorage‐independent cell growth by inhibiting p53. Collectively, these findings reveal a critical role for FBXO46 in controlling Mdm2 stability and establish FBXO46 as an important regulator of the Mdm2–p53 pathway. [ABSTRACT FROM AUTHOR]

RNA splicing enables the functional adaptation of cells to changing contexts. Impaired splicing has been associated with diseases, including retinitis pigmentosa, but the underlying molecular mechanisms and cellular responses remain poorly understood. In this work, we report that deficiency of ubiquitin-specific protease 39 (USP39) in human cell lines, zebrafish larvae, and mice led to impaired spliceosome assembly and a cytotoxic splicing profile characterized by the use of cryptic 5′ splice sites. Disruptive cryptic variants evaded messenger RNA (mRNA) surveillance pathways and were translated into misfolded proteins, which caused proteotoxic aggregates, endoplasmic reticulum (ER) stress, and, ultimately, cell death. The detrimental consequence of splicing-induced proteotoxicity could be mitigated by up-regulating the ubiquitin-proteasome system and selective autophagy. Our findings provide insight into the molecular pathogenesis of spliceosome-associated diseases. [ABSTRACT FROM AUTHOR]

Mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth and its dysregulation leads to a variety of human diseases. Although NPRL2, an essential component of the GATOR1 complex, is reported to effectively suppress amino acid‐induced mTORC1 activation, the regulation of NPRL2 protein stability is unclear. In this study, we show that chaperon‐associated ubiquitin ligase CHIP interacts with NPRL2 and promotes its polyubiquitination and proteasomal degradation. Moreover, HSP70 mediates CHIP‐induced ubiquitination and degradation of NPRL2. Consistently, overexpression of HSP70 enhances whereas HSP70 depletion inhibits amino acid‐induced mTORC1 activation. Accordingly, knockdown of HSP70 promotes basal autophagic flux, and inhibits cell growth and proliferation. Taken together, these results demonstrated that HSP70 is a novel activator of mTORC1 through mediating CHIP‐induced ubiquitination and degradation of NPRL2. [ABSTRACT FROM AUTHOR]

Post-translational modifications (PTMs) of proteins play a significant role in normal protein function but can also be instrumental in disease pathogenesis. One critical yet under-studied PTM in disease is ubiquitination. Ubiquitin chain addition and substrate specificity are determined by a large spectrum of ubiquitin-ligating and -modifying enzymes, E3 ligases, whose expression levels and activities are tightly regulated in a cell-specific manner. While most ubiquitin chains can target proteins for proteasomal degradation, ubiquitination can contribute to other functions within the cell, including protein localization, protein activity, endocytosis, transcription, and autophagy. One E3 ligase, UBE3A, has garnered much attention because of its involvement in learning and memory, as well as its association with neurodevelopmental autism spectrum disorders (ASDs). However, more recent findings have suggested a potential involvement of UBE3A in neurodegenerative proteinopathies, where reduced UBE3A levels can lead to an enhanced rate of aggregate formation and cell death. Here, we review the literature on UBE3A in neurodevelopment, function, and neurodegenerative diseases and demonstrate that UBE3A could play a critical role in disease progression and cognitive function. [ABSTRACT FROM AUTHOR]

Background: Long non-coding RNA (lncRNA) plays a vital role in the occurrence and development of varieties of tumors. Previous studies have shown that lncRNA GClnc1 is highly expressed in osteosarcoma (OS). However, the mechanism of lncRNA GClnc1 in osteosarcoma has not been fully elucidated. In this study, we investigated the biological roles of lncRNA GClnc1 in osteosarcoma and unveiled its underlying mechanisms. Methods: The expression of lncRNA GClnc1 in OS cells was detected by real-time quantitative PCR (qRT-PCR). The functional roles of lncRNA GClnc1 were examined by CCK8, trans-well, scratch wound healing assay, colony formation, and apoptosis assays in osteosarcoma cells upon silencing or overexpressing GClnc1. Western blot analysis, qRT-PCR, and RNA co-immunoprecipitation (RIP) assays were used to detect the interaction between lncRNA GClnc1 and NONO. Results: The expression of lncRNA GClnc1 was up-regulated in osteosarcoma cell lines. Knockdown of lncRNA GClnc1 suppressed the cell growth, migration, and invasion of OS cells, whereas the over-expression of GClnc1 improved the proliferation, migration, and invasion of OS cells. Mechanistically, we identified that lncRNA GClnc1 regulates the stability of NONO by blocking FBXW7-mediated ubiquitination degradation. Additionally, overexpression of NONO can reverse GClnc1 silencing exerted suppression of the cell proliferation, migration, and invasion, and vice versa. Conclusions: Our study elucidated that lncRNA GClnc1 participates in the progression of OS by regulating the NONO signal pathway. Targeting GClnc1 provides a potential target for future clinical treatment of OS. [ABSTRACT FROM AUTHOR]

Alzheimer's Disease (AD), as the most common neurodegenerative disease worldwide, severely impairs patients' cognitive functions. Although its exact etiology remains unclear, the abnormal aggregations of misfolded β-amyloid peptide and tau protein are considered pivotal in its pathological progression. Recent studies identify ubiquitin-specific protease 11 (USP11) as the key regulator of tau deubiquitination, exacerbating tau aggregation and AD pathology. Thereby, inhibiting USP11 function, via either blocking USP11 activity or lowering USP11 protein level, may serve as an effective therapeutic strategy against AD. Our research introduces IsoLiPro, a unique lithium isobutyrate-L-proline coordination compound, effectively lowers USP11 protein level and enhances tau ubiquitination in vitro. Additionally, long-term oral administration of IsoLiPro dramatically reduces total and phosphorylated tau levels in AD transgenic mice. Moreover, IsoLiPro also significantly lessens β-amyloid deposition and synaptic damage, improving cognitive functions in these animal models. These results indicate that IsoLiPro, as a novel small-molecule USP11 inhibitor, can effectively alleviate AD-like pathologies and improve cognitive functions, offering promise as a potential multi-targeting therapeutic agent against AD. Synopsis: In Alzheimer's disease (AD), USP11 interacts with and deubiquitinates tau, leading to its accumulation and accelerating tau pathology. IsoLiPro promotes the ubiquitination and proteolysis of tau protein by inhibiting the expression of USP11, thereby alleviating AD-associated tau pathologies. IsoLiPro, a small molecule inhibitor targeting USP11, was synthesized and demonstrated the ability to enhance tau ubiquitination. Inhibition of USP11 expression by IsoLiPro accelerates tau proteolysis, mitigating AD-associated tau pathology. A significant reduction in β-amyloid deposition was observed in 5xFAD mice treated with IsoLiPro. IsoLiPro improved synaptic integrity and cognitive function in AD model mice. IsoLiPro shows promise as a potential therapeutic agent for AD. In Alzheimer's disease (AD), USP11 interacts with and deubiquitinates tau, leading to its accumulation and accelerating tau pathology. IsoLiPro promotes the ubiquitination and proteolysis of tau protein by inhibiting the expression of USP11, thereby alleviating AD-associated tau pathologies. [ABSTRACT FROM AUTHOR]

X-linked inhibitor of apoptosis-associated factor 1 (XAF1) is a stress-inducible pro-apoptotic protein that is commonly inactivated in multiple human cancers. Nevertheless, the molecular basis for its tumor suppression function remains largely uncharacterized. Here we report that XAF1 antagonizes the oncogenic activity of tripartite motif containing 28 (TRIM28) ubiquitin E3 ligase through zinc finger protein 313 (ZNF313)-induced ubiquitination and proteasomal degradation. XAF1 exerts apoptosis-promoting effect more strongly in TRIM28+/+ versus XAF1−/− tumor cells and suppresses tumor cell growth, migration, invasion, and epithelial-to-mesenchymal transition and xenograft tumor growth in a highly TRIM28-dependent fashion. Mechanistically, XAF1 interacts directly with the RING domains of TRIM28 and ZNF313 through the ZF6 and ZF7 domain, respectively, thereby facilitating ZNF313 interaction with and ubiquitination of TRIM28. A mutant XAF1 lacking either ZF6 or ZF7 domain exhibits no activity to promote TRIM28 ubiquitination. By destabilizing TRIM28, XAF1 blocks TRIM28-driven ubiquitination of p53 and RLIM, p53-HDAC1 interaction, and TWIST1 stabilization. Intriguingly, TRIM28 destabilizes XAF1 through K48-linked polyubiquitination and proteasomal degradation to protect tumor cells from apoptotic stress, indicating its role as an intrinsic antagonist against XAF1 and the antagonistic interplay of XAF1 and TRIM28. XAF1 expression is inversely correlated with TRIM28 expression in cancer cell lines and tumor tissues and more tightly associated with the survival of TRIM28-high versus TRIM28-low patients. Together, this study uncovers a novel mechanism by which XAF1 suppresses tumor malignancy and an important role for XAF1-TRIM28 interplay in governing stress response, illuminating the mechanistic consequence of its alteration during tumorigenic process. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a high-incidence, poor-prognosis malignancy worldwide, requiring new strategies for treatment. Ubiquitination, especially ubiquitination through E3 ubiquitin ligases, plays an indispensable role in the development and progression of HCC. E3 ubiquitin ligases are crucial enzymes in ubiquitination, controlling the degradation of specific substrate proteins and influencing various cellular functions, such as tumor cell proliferation, apoptosis, migration, and immune evasion. In this review, we systematically summarize the mechanisms of E3 ubiquitin ligases in HCC, with a focus on the significance of RING, HECT, and RBR types in HCC progression. The review also looks at the potential for targeting E3 ligases to modulate the tumor microenvironment (TME) and increase immunotherapy efficacy. Future studies will optimize HCC treatment by formulating specific inhibitors or approaches that will be based on gene therapy targeting E3 ligases in order to overcome resistance issues with present treatments and create optimism in the journey of treatment for HCC patients. [ABSTRACT FROM AUTHOR]

The expression of TRIM47, a member of the TRIM protein and E3 ubiquitin ligase families, is elevated in various cancers, such as non-small cell lung cancer and colorectal cancer, and is linked to poor prognosis. This study aimed to investigate the role of TRIM47 in gastric cancer development. Using The Cancer Genome Atlas-Stomach Adenocarcinoma (TCGA-STAD) dataset and analysis of 20 patient samples from our center, TRIM47 was found to be significantly up-regulated in gastric cancer tissues and associated with advanced N-stage and poor prognosis. We constructed stable TRIM47 knockdown and overexpressing gastric cancer cell lines. CCK8, EDU, colony formation, wound healing, and Transwell tests were used to evaluate the effects on cell proliferation, invasion, and migration. The results showed that TRIM47 knockdown inhibited the proliferation, migration and invasion of gastric cancer cells, while TRIM47 overexpression promoted these behaviors. These results were further confirmed in vivo. In the mechanism part, we found that TRIM47 interacts with CYLD protein. Moreover, TRIM47 promotes K48-linked ubiquitination, leading to the degradation of CYLD by the proteasome, thereby activating the NF-κB pathway and regulating the biological behavior of gastric cancer cells. Taken together, our study demonstrated that TRIM47 is involved in the proliferation and metastasis of gastric cancer through the CYLD/NF-κB pathway. [ABSTRACT FROM AUTHOR]

RIG-I-like receptors (RLRs) are cytosolic RNA sensors critical for antiviral immunity. RLR activation is regulated by polyubiquitination and oligomerization following RNA binding. Yet, little is known about how RLRs exploit subcellular organelles to facilitate their posttranslational modifications and activation. Endosomal adaptor TAPE regulates the endosomal TLR and cytosolic RLR pathways. The potential interplay between RIG-I signaling and endosomes has been explored. Here, we report that endosomes act as platforms for facilitating RIG-I polyubiquitination and complex formation. RIG-I was translocated onto endosomes to form signaling complexes upon activation. Ablation of endosomes impaired RIG-I signaling to type I IFN activation. TAPE mediates the interaction and polyubiquitination of RIG-I and TRIM25. TAPE-deficient myeloid cells were defective in type I IFN activation upon RNA ligand and virus challenges. Myeloid TAPE deficiency increased the susceptibility to RNA virus infection in vivo. Our work reveals endosomes as signaling platforms for RIG-I activation and antiviral immunity. [ABSTRACT FROM AUTHOR]

Signaling through the Wnt/β‐catenin pathway is relayed through three multiprotein complexes: (1) the membrane‐associated signalosome, which includes the activated Wnt receptors, (2) the cytoplasmic destruction complex that regulates turnover of the transcriptional coactivator β‐catenin, and (3) the nuclear enhanceosome that mediates pathway‐specific transcription. Recent discoveries have revealed that Wnt receptor activities are tightly regulated to maintain proper tissue homeostasis and that aberrant receptor upregulation enhances Wnt signaling to drive tumorigenesis, highlighting the importance of signalosome control. These studies have focused on the detailed process by which Wnt ligands engage their coreceptors, LRP5/6 and Frizzled. However, the components that constitute the signalosome and the regulation of their assembly remain undefined. In this review, we discuss Wnt/β‐catenin signalosome composition and the mechanisms that regulate signalosome assembly, including the role of biomolecular condensates and ubiquitylation. We also summarize the evidence for the presence of Wnt ligand‐independent signalosome formation. [ABSTRACT FROM AUTHOR]

Increasing evidence supports the crucial role of Epithelial-Mesenchymal Transition (EMT) in cancer invasion and metastasis. N-acetylglucosaminyltransferase V (MGAT5), which is associated with multiantenna glycosylation, can contribute to tumorigenesis, yet its specific role in promoting colorectal cancer (CRC) metastasis remains unclear. Bioinformatics analysis of CRC datasets revealed that elevated MGAT5 expression was associated with EMT and a poor prognosis. In vitro experiments confirmed the pivotal role of MGAT5 as an EMT regulator in CRC cells. MGAT5 overexpression stimulated cell proliferation and migration, while MGAT5 knockdown had the opposite effect. Mechanistically, MGAT5 promoted EMT through multiantenna glycosylation of ZO-1, promoting its ubiquitination and reducing its expression. Clinically, MGAT5 upregulation in the CRC TMA correlated negatively with ZO-1 expression, which is indicative of malignancy and a poor prognosis. This study revealed that MGAT5 promotes EMT in CRC via interactions between multiple antenna glycosylation products and ZO-1 ubiquitination/degradation, indicating that MGAT5 could serve as a promising therapeutic target for CRC. [ABSTRACT FROM AUTHOR]

Background: The role of the RING finger protein superfamily in carcinogenesis has been widely studied, but one member of this family, RNF19A, has not yet been thoroughly explored in bladder cancer (BCa). Methods: The expression levels of RNF19A in BCa samples and cell lines were analysed through data mining of public resources and further experiments. BCa cells in which RNF19A was stably overexpressed or knocked down were generated through lentivirus infection. The effects of RNF19A on cell proliferation, migration, and invasion were explored by performing a series of in vitro experiments, including CCK-8, colony formation, wound healing, and Transwell invasion assays. Using bioinformatics methods and multiple experiments, including western blot, qRT‒PCR, immunoprecipitation, cycloheximide, ubiquitination, and rescue assays, the mechanism underlying the effect of RNF19A on the progression of BCa was investigated. Results: Here, we found that RNF19A expression was reduced in BCa samples and cell lines and that lower RNF19A expression predicted shorter overall survival of BCa patients. Functionally, forced expression of RNF19A suppressed BCa cell proliferation, migration, and invasion by inactivating the AKT/mTOR signalling pathway, whereas silencing RNF19A had the opposite effects. Mechanistically, RNF19A could directly interact with ILK and promote its ubiquitination and degradation. Rescue experiments revealed that forced ILK expression partially rescued the decreased phosphorylation of AKT, mTOR, and S6K1 caused by RNF19A overexpression and that the increased levels of the p-AKT, p-mTOR, and p-S6K1 proteins induced by RNF19A knockdown were eliminated after silencing ILK. Similarly, the effects of RNF19A overexpression or knockdown on the phenotypes of cell proliferation, migration, and invasion could also be restored by forced or decreased ILK expression. Conclusions: RNF19A suppressed the proliferation, migration, and invasion abilities of BCa cells by regulating ILK ubiquitination and inactivating the AKT/mTOR signalling pathway. RNF19A might be a potential prognostic biomarker and promising therapeutic target for BCa. [ABSTRACT FROM AUTHOR]

Obstructive sleep apnea (OSA) is a common sleep disorder characterized by intermittent hypoxia (IH) and is associated with the occurrence and development of nonalcoholic fatty liver disease (NAFLD). However, the specific mechanism by which OSA induces NAFLD remains unclear. Therefore, effective interventions are lacking. This study aims to investigate the role and mechanism of ferroptosis in OSA‐related NAFLD using clinical data analyses, cell‐based molecular experiments, and animal experiments. Indicators of liver function, lipid accumulation, and ferroptosis are also examined. RNA‐seq, qPCR, western blotting, gene intervention, and E3 ligase prediction using UbiBrowser and co‐IP are used to explore the potential underlying mechanisms. The results show that ferroptosis increases in the liver tissues of patients with OSA. Chronic IH promotes NAFLD progression in mice and is alleviated by a ferroptosis inhibitor Fer‐1. The increased secretion of IL6 by macrophages can promote the expression of MARCH3 in hepatocytes under intermittent conditions, and subsequently promote the ubiquitination and degradation of GPX4 to regulate ferroptosis and lipid accumulation in hepatocytes. Hence, targeted inhibition of MARCH3 may alleviate IH‐induced ferroptosis and lipid accumulation in liver tissues and inhibit the progression of NAFLD. [ABSTRACT FROM AUTHOR]

Inflammatory bowel disease (IBD) is a disorder causing chronic inflammation in the gastrointestinal tract, and its pathophysiological mechanisms are still under investigation. Here, we find that mice deficient of YOD1, a deubiquitinating enzyme, are highly susceptible to dextran sulfate sodium (DSS)-induced colitis. The bone marrow transplantation experiment reveals that YOD1 derived from hematopoietic cells inhibits DSS colitis. Moreover, YOD1 exerts its protective role by promoting nucleotide-binding oligomerization domain 2 (NOD2)-mediated physiological inflammation in macrophages. Mechanistically, YOD1 inhibits the proteasomal degradation of receptor-interacting serine/threonine kinase 2 (RIPK2) by reducing its K48 polyubiquitination, thereby increasing RIPK2 abundance to enhance NOD2 signaling. Consistently, the protective function of muramyldipeptide, a NOD2 ligand, in experimental colitis is abolished in mice deficient of YOD1. Importantly, YOD1 is upregulated in colon-infiltrating macrophages in patients with colitis. Collectively, this study identifies YOD1 as a novel regulator of colitis. Synopsis: NOD2-mediated physiological inflammation is critical for maintaining intestinal homeostasis. The deubiquitinating enzyme YOD1 potentiates protective NOD2 signaling by stabilizing RIPK2, thereby ameliorating intestinal inflammation and colitis. Deficiency of YOD1 in hematopoietic cells exacerbates DSS-induced experimental colitis in mice. YOD1 is highly expressed in mucosa-infiltrating macrophages and potentiates inflammatory responses in macrophages. YOD1 enhances NOD2 signaling by stabilizing RIPK2 through K48 deubiquitylation. NOD2-mediated physiological inflammation is critical for maintaining intestinal homeostasis. The deubiquitinating enzyme YOD1 potentiates protective NOD2 signaling by stabilizing RIPK2, thereby ameliorating intestinal inflammation and colitis. [ABSTRACT FROM AUTHOR]

The transcription factor TFEB is a major regulator of lysosomal biogenesis and autophagy. There is growing evidence that posttranslational modifications play a crucial role in regulating TFEB activity. Here, we show that lactate molecules can covalently modify TFEB, leading to its lactylation and stabilization. Mechanically, lactylation at K91 prevents TFEB from interacting with E3 ubiquitin ligase WWP2, thereby inhibiting TFEB ubiquitination and proteasome degradation, resulting in increased TFEB activity and autophagy flux. Using a specific antibody against lactylated K91, enhanced TFEB lactylation was observed in clinical human pancreatic cancer samples. Our results suggest that lactylation is a novel mode of TFEB regulation and that lactylation of TFEB may be associated with high levels of autophagy in rapidly proliferating cells, such as cancer cells. [ABSTRACT FROM AUTHOR]

Summary The endoplasmic reticulum‐associated degradation (ERAD) system eliminates misfolded and short‐lived proteins to maintain physiological homeostasis in the cell. We have previously reported that ERAD is involved in salt tolerance in Arabidopsis. Given the central role of the phytohormone abscisic acid (ABA) in plant stress responses, we sought to identify potential intersections between the ABA and the ERAD pathways in plant stress response. By screening for the ABA response of a wide array of ERAD mutants, we isolated a gain‐of‐function mutant, doa10a‐1, which conferred ABA hypersensitivity to seedlings. Genetic and biochemical assays showed that DOA10A is a functional E3 ubiquitin ligase which, by acting in concert with specific E2 enzymes, mediates mono‐ubiquitination of the ABA receptor, followed by their relocalization to the plasma membrane. This in turn leads to enhanced ABA perception. In summary, we report here the identification of a novel RING‐type E3 ligase, DOA10A, which regulates ABA perception by affecting the localization and the activity of ABA receptors through their mono‐ubiquitination. [ABSTRACT FROM AUTHOR]

Summary In Magnaporthe oryzae, the Pmk1 MAP kinase signaling pathway regulates appressorium formation, plant penetration, effector secretion, and invasive growth. While the Mst11‐Mst7‐Pmk1 cascade was characterized two decades ago, knowledge of its signaling in the intracellular network remains limited. In this study, we demonstrate that the endosomal surface scaffolds Pmk1 MAPK signaling and Msb2 activates Ras2 on endosomes in M. oryzae. Protein colocalization demonstrated that Msb2, Ras2, Cap1, Mst50, Mst11, Mst7, and Pmk1 attach to late endosomal membranes. Damage to the endosome–vacuole transport system influences Pmk1 phosphorylation. When Msb2 senses a plant signal, it internalizes and activates Ras2 on endosome membrane surfaces, transmitting the signal to Pmk1 via Mst11 and Mst7. Signal‐sensing and delivery proteins are ubiquitinated and sorted for degradation in late endosomes and vacuoles, terminating signaling. Plant penetration and lowered intracellular turgor are required for the transition from late endosomes to vacuoles in appressoria. Our findings uncover an effective mechanism that scaffolds and controls Pmk1 MAPK signaling through endosomal–vacuolar transport, offering new knowledge for the cytological and molecular mechanisms by which the Pmk1 MAPK pathway modulates development and pathogenicity in M. oryzae. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a detrimental heavy metal propagated from soil to the food chain via plants, posing a great risk to human health upon consumption. Despite the understanding of Cd tolerance mechanisms in plants, whether and how plants actively respond to Cd and in turn restrict its uptake and accumulation remain elusive. Here, we identify a cell wall-associated receptor-like kinase 4 (WAKL4) involved in specific tolerance to Cd stress. We show that Cd rapidly and exclusively induces WAKL4 accumulation by promoting WAKL4 transcription and blocking its vacuole-dependent proteolysis in roots. The accumulated WAKL4 next interacts with and phosphorylates the Cd transporter NRAMP1 at Tyr488, leading to the enhanced ubiquitination and vacuole-dependent degradation of NRAMP1, and consequently reducing Cd uptake. Our findings therefore uncover a mechanism conferred by the WAKL4-NRAMP1 module that enables plants to actively respond to Cd and limit its uptake, informing the future molecular breeding of low Cd accumulated crops or vegetables. This study demonstrates a WAKL4 receptor-like kinase that is rapidly and specifically induced by Cadmium. It reveals a unique mechanism conferred by the WAKL4-NRAMP1 module that enables plants to actively respond to Cadmium and limit its uptake. [ABSTRACT FROM AUTHOR]

Background: Doxorubicin (DOX) is an effective anticancer drug, but it has a problem of cardiotoxicity that cannot be ignored. Ca2+/calmodulin‐dependent protein kinase II (CaMKII) is tightly associated with the pathological progression of DOX‐induced cardiotoxicity. Ubiquitin‐specific protease 10 (USP10) plays an important role in many biological processes and cancers. However, its association with DOX‐induced cardiotoxicity and CaMKII remains unclear. Methods: H9C2 cells, HL‐1 cells and C57BL/6 mice were used to establish the DOX‐induced cardiotoxicity model, and the CaMKII‐specific inhibitor KN‐93 and USP10 specific inhibitor Spautin‐1 were used to observe the CaMKII and USP10 effect. In cell experiments, CCK‐8 method was used to assess cell viability, LDH kit was used to assess lactate dehydrogenase expression, DCFH‐DA staining was used to observe changes in active oxygen content, TUNEL staining was used to observe cell apoptosis, and Western blotting method was used to detect relevant protein markers. The expression of p‐CaMKII and USP10 was assessed by immunofluorescence staining. In animal experiments, mouse echocardiograph was used were used to evaluate cardiac function, and HE staining and Masson staining were used to evaluate myocardial injury. Cardiomyocyte apoptosis was detected by TUNEL staining. Western blotting method was used to detect relevant protein markers. Results: Our results demonstrated that activation of CaMKII and inhibition of USP10 pathway related to DOX‐induced cardiotoxicity. Inhibition of CaMKII with KN‐93 ameliorated DOX‐induced cardiac dysfunction and cytotoxicity. In addition, CaMKII inhibition prevented DOX‐induced apoptosis and ubiquitination. Furthermore, CaMKII inhibition increased USP10 expression in DOX‐treated mouse hearts, H9C2 cells and HL‐1 cells. At last, the USP10 inhibitor, Spautin‐1, blocked the regulatory effect of CaMKII inhibition on apoptosis and ubiquitination in DOX‐induced cardiotoxicity. Conclusion: Our findings revealed that DOX‐induced myocardial apoptosis and activated CaMKII through cellular and animal levels, while providing a novel probe into the mechanism of CaMKII action: promoting ubiquitination by inhibiting USP10 aggravated apoptosis. [ABSTRACT FROM AUTHOR]

Cyclic GMP–AMP (cGAMP) synthase (cGAS) senses DNA in a sequence-independent manner, triggering cGAMP synthesis, which activates stimulator of interferon genes (STING) and the subsequent expression of type I interferons, tumour necrosis factor alpha (TNF-α) and other proinflammatory factors in two downstream pathways. However, the function of the cGAS STING pathway in γδ T cells remains unclear. The γδ T-cell population differs from the innate-like lymphocyte population, particularly with respect to tissue distribution, indicating the unique potential of γδ T cells in treating infections and cancers. On the basis of accumulating evidence, cGAS activity is modulated by protein posttranslational modifications (PTMs), including phosphorylation, O-GlcNAcylation, acetylation, ubiquitylation and methylation, which affect multiple cGAS functions. Thus, here, we summarize recent research on PTMs of the cGAS protein that modulate γδ T-cell function. An understanding of cGAS features and modulation mechanisms may facilitate the design of therapies for γδ T-cell-related immune diseases and cancer. • The role of cGAS-STING pathway in γδ T cells. • Posttranslational modifications (PTMs) of the cGAS protein can modulate γδ T-cell function. • Therapies for γδ T-cell-related immune diseases and cancer. [ABSTRACT FROM AUTHOR]

Diffuse large B‐cell lymphoma (DLBCL) is the most common subtype of non‐Hodgkin lymphoma and is associated with a poor prognosis. Data from the Gene Expression Profiling Interactive Analysis (GEPIA) database revealed dysregulated expression of several ubiquitin‐specific proteases (USPs) in DLBCL tissues (DLBCL vs. non‐DLBCL = 47 vs. 337), including USP19 (log2fold change = 1.17, P < 0.05). USP19 is closely linked to tumorigenesis, but its role in DLBCL progression remains largely unknown. Here, we investigated the role of USP19 in DLBCL development. Genetic manipulation of USP19 using adenovirus‐based vectors was performed in two DLBCL cell lines, SUDHL4 and DB cells. The results showed that USP19 knockdown suppressed the proliferation, anchorage‐independent growth and xenograft tumor formation of DLBCL cells and arrested the cell cycle at the G1 stage. In parallel, DLBCL cells overexpressing USP19 acquired a more malignant phenotype. Next, to explore USP19 interactors, we performed co‐immunoprecipitation/liquid chromatography–mass spectrometry and identified potential interacting proteins. Among them, Parkinson disease protein 7 (PARK7), a member of the peptidase C56 family known to be involved in carcinogenesis, was further validated to bind with and be stabilized by USP19. Additionally, we found that USP19 induced PARK7 deubiquitylation in both DLBCL cell lines, and PARK7 acted as a downstream effector of USP19 in regulating the growth of DLBCL cells. Collectively, USP19 exerts a tumor‐promoting role in DLBCL through interacting with and stabilizing PARK7. [ABSTRACT FROM AUTHOR]

Developing resistance to cancer treatments is a major challenge, often leading to disease recurrence and metastasis. Understanding the underlying mechanisms of therapeutic resistance is critical for developing effective strategies. O-GlcNAcylation, a post-translational modification that adds GlcNAc from the donor UDP-GlcNAc to serine and threonine residues of proteins, plays a crucial role in regulating protein function and cellular signaling, which are frequently dysregulated in cancer. Similarly, ubiquitination, which involves the attachment of ubiquitin to to proteins, is crucial for protein degradation, cell cycle control, and DNA repair. The interplay between O-GlcNAcylation and ubiquitination is associated with cancer progression and resistance to treatment. This review discusses recent discoveries regarding the roles of O-GlcNAcylation and ubiquitination in cancer resistance, their interactions, and potential mechanisms. It also explores how targeting these pathways may provide new opportunities to overcome cancer treatment resistance in cancer, offering fresh insights and directions for research and therapeutic development. [ABSTRACT FROM AUTHOR]

Objective(s): Quercetin is a plant flavonoid known for its pharmacological activities, such as antioxidant, anti-inflammatory, and anti-cancer properties. However, there is limited information available regarding its potential toxicities. A previous study showed that quercetin can inhibit human ether-a-go-related gene (hERG, also named KCNH2) currents, which may lead to long QT syndrome, torsade de pointes (TdP), and even sudden cardiac death. This study aimed to investigate the effects of quercetin on hERG and its potential mechanism. Materials and Methods: hERG currents and action potential duration (APD) were assessed using the patch clamp technique. Molecular docking was employed to elucidate the binding sites between quercetin and hERG. Transfection of wild-type or mutant plasmids was used to verify the results of molecular docking. Western blot was performed to determine the expression levels of hERG, transcription factor SP1, molecular chaperones HSP70 and HSP90, phosphorylated E3 ubiquitin ligase p-Nedd4-2, serum- and glucocorticoid-inducible kinase (SGK1), and phosphatidylinositol 3-kinase (PI3K). Immunoprecipitation was conducted to evaluate hERG ubiquitination. Results: Quercetin acutely blocked hERG current by binding to F656 amino acid residue, subsequently accelerating channel inactivation. Long-term incubation of quercetin accelerates Nedd4-2-mediated ubiquitination degradation of hERG channels by inhibiting the PI3K/SGK1 signaling pathway. Moreover, the APD of human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) is significantly prolonged by 30 µM quercetin. Conclusion: Quercetin has a potential risk of proarrhythmia, which provided useful information for the usage and development of quercetin as a medication. [ABSTRACT FROM AUTHOR]

Every year, unfavorable environmental factors significantly affect crop productivity and threaten food security. Plants are sessile; they cannot move to escape unfavorable environmental conditions, and therefore, they activate a variety of defense pathways. Among them are processes regulated by stress‐associated proteins (SAPs). SAPs have a specific zinc finger domain (A20) at the N‐terminus and either AN1 or C2H2 at the C‐terminus. SAP proteins are involved in many biological processes and in response to various abiotic or biotic constraints. Most SAPs play a role in conferring transgenic stress resistance and are stress‐inducible. The emerging field of SAPs in abiotic or biotic stress response regulation has attracted the attention of researchers. Although SAPs interact with various proteins to perform their functions, the exact mechanisms of these interactions remain incompletely understood. This review aims to provide a comprehensive understanding of SAPs, covering their diversity, structure, expression, and subcellular localization. SAPs play a pivotal role in enabling crosstalk between abiotic and biotic stress signaling pathways, making them essential for developing stress‐tolerant crops without yield penalties. Collectively, understanding the complex regulation of SAPs in stress responses can contribute to enhancing tolerance against various environmental stresses through several techniques such as transgenesis, classical breeding, or gene editing. [ABSTRACT FROM AUTHOR]

Sepsis‐induced acute lung injury (ALI) is characterized by inflammatory damage to pulmonary endothelial and epithelial cells. The aim of this study is to probe the significance and mechanism of tripartite motif‐containing protein 21 (TRIM21) in sepsis‐induced ALI. The sepsis‐induced ALI mouse model was established by cecum ligation and puncture. The mice were infected with lentivirus and treated with proteasome inhibitor MG132. The lung respiratory damage, levels of interleukin‐6 (IL‐6), tumour necrosis factor α (TNF‐α), IL‐10 and pathological changes were observed. The expression levels of TRIM21, interferon regulatory factors 1 (IRF1) and triggering receptor expressed on myeloid cells 2 (TREM2) were measured and their interactions were analysed. The ubiquitination level of IRF1 was detected. TRIM21 and TREM2 were downregulated and IRF1 was upregulated in sepsis‐induced ALI mice. TRIM21 overexpression eased inflammation and lung injury. TRIM21 promoted IRF1 degradation via ubiquitination modification. IRF1 bonded to the TREM2 promoter to inhibit its transcription. Overexpression of IRF1 or silencing TREM2 reversed the improvement of TRIM21 overexpression on lung injury in mice. In conclusion, TRIM21 reduced IRF1 expression by ubiquitination to improve TREM2 expression and ameliorate sepsis‐induced ALI. [ABSTRACT FROM AUTHOR]

Summary: In Arabidopsis, the enzymatically active lysin motif‐containing receptor‐like kinase (LysM‐RLK) CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1) and the pseudokinases LYSIN MOTIF‐CONTAINING RECEPTOR‐LIKE KINASE 5 (LYK5) and LYK4 are the core components of the canonical chitin receptor complex. CERK1 dimerizes and autophosphorylates upon chitin binding, resulting in activation of chitin signaling.In this study, we clarified and further elucidated the individual contributions of LYK4 and LYK5 to chitin‐dependent signaling using mutant (combination)s and stably transformed Arabidopsis plants expressing fluorescence‐tagged LYK5 and LYK4 variants from their endogenous promoters.Our analyses revealed that LYK5 interacts with CERK1 upon chitin treatment, independently of LYK4 and vice versa. We show that chitin‐induced autophosphorylation of CERK1 is predominantly dependent on LYK5, whereas chitin‐triggered ROS generation is almost exclusively mediated by LYK4. This suggests specific signaling functions of these two co‐receptor proteins apart from their redundant function in mitogen‐activated protein kinase (MAPK) signaling and transcriptional reprogramming.Moreover, we demonstrate that LYK5 is subject to chitin‐induced and CERK1‐dependent ubiquitination, which serves as a signal for chitin‐induced internalization of LYK5. Our experiments provide evidence that a combination of phosphorylation and ubiquitination events controls LYK5 removal from the plasma membrane via endocytosis, which likely contributes to receptor complex desensitization. [ABSTRACT FROM AUTHOR]

Summary: Arabidopsis PSEUDORESPONSE REGULATOR7 (PRR7) is a core component of the circadian oscillator which also plays a crucial role in freezing tolerance. PRR7 undergoes proteasome‐dependent degradation to discretely phase maximal expression in early evening. While its repressive activity on downstream genes is integral to cold regulation, the mechanism of the conditional regulation of the PRR7 abundance is unknown.We used mutant analysis, protein interaction and ubiquitylation assays to establish that the ubiquitin ligase adaptor, HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE 15 (HOS15), controls the protein accumulation pattern of PRR7 through direct protein–protein interactions at low temperatures. Freezing tolerance and electrolyte leakage assays show that PRR7 enhances cold temperature sensitivity, supported by ChIP‐qPCR at C‐REPEAT BINDING FACTOR1 (CBF1) and COLD‐REGULATED 15A (COR15A) promoters where PRR7 levels were higher in hos15 mutants.HOS15 mediates PRR7 turnover through enhanced ubiquitylation at low temperature in the dark. Under the same conditions, increased PRR7 association with the promoters of CBFs and COR15A in hos15 correlates with decreased CBF1 and COR15A transcription and enhanced freezing sensitivity.We propose a novel mechanism whereby HOS15‐mediated degradation of PRR7 provides an intersection between the circadian system and other cold acclimation pathways that lead to increased freezing tolerance. [ABSTRACT FROM AUTHOR]

Autophagy is an important lysosomal degradation process that digests and recycles bio-molecules, protein or lipid aggregates, organelles, and invaded pathogens. Autophagy plays crucial roles in regulation of metabolic and oxidative stress and multiple pathological processes. In cancer, the role of autophagy is dual and paradoxical. Ubiquitination has been identified as a key regulator of autophagy that can influence various steps in the autophagic process, with autophagy-related proteins being targeted for ubiquitination, thus impacting cancer progression and the effectiveness of therapeutic interventions. This review will concentrate on mechanisms underlying autophagy, ubiquitination, and their interactions in cancer, as well as explore the use of drugs that target the ubiquitin-proteasome system (UPS) and ubiquitination process in autophagy as part of cancer therapy. [ABSTRACT FROM AUTHOR]

Introduction: β-Elemene, derived from Curcuma zedoaria (Wenyujin), is clinically recognized for inducing apoptosis, inhibiting cell cycle progression, and reversing chemotherapy resistance in various cancers. However, its effects on radioresistant gastric cancer (GC) remain unclear. Methods: In this study, radioresistant GC cell lines (MKN45/IR and AGS/IR) were established via multiple low-dose radiations. The impact of β-elemene on radiosensitivity was assessed using CCK-8 and clonogenic assays, with ferroptosis markers such as ROS, MDA, and Fe2+ levels measured. Additionally, the influence of β-elemene on GPX4 and its interaction with OTUB1 was examined through qRT-PCR, Western blot, immunofluorescence, coimmunoprecipitation, and in vivo studies. Results: Our findings indicate that β-elemene reverses radioresistance in GC cells and significantly inhibits cell growth when combined with radiotherapy. β-Elemene treatment elevated ROS, MDA, and Fe2+ levels, enhancing ferroptosis, which was confirmed by Ferrostatin-1 and Deferoxamine inhibition studies. Mechanistic analysis revealed that β-elemene disrupts the OTUB1-GPX4 interaction, leading to increased GPX4 ubiquitination and degradation, thus promoting ferroptosis. In vivo studies further demonstrated that β-elemene combined with radiotherapy significantly suppressed tumor growth compared to radiotherapy alone. Discussion: These results suggest that β-elemene effectively modulates radioresistance in GC by targeting the GPX4 pathway and inducing ferroptosis. This highlights its potential as a therapeutic adjunct in radiotherapy for resistant GC cases. [ABSTRACT FROM AUTHOR]

Effective inhibition of intestinal lipid uptake is an efficient strategy for the treatment of disorders related to lipid metabolism. Sterol O‐acyltransferase 2 (SOAT2) is responsible for the esterification of free cholesterol and fatty acids into cholesteryl esters. We found that intestine‐specific SOAT2 knockout (Soat2I‐KO) mice was capable to prevent the development of dietary induced obesity due to reduced intestinal lipid absorption. Soat2 siRNA/CS‐PLGA nanoparticle system was constructed to enable intestinal delivery and inhibition of Soat2. This nanoparticle system was composed of PLGA‐block‐PEG and chitosan specifically delivering Soat2 siRNAs into small intestines in mice, effectively inhibit intestinal lipid uptake and resolving obesity. In revealing the underlying mechanism by which intestinal SOAT2 regulating fatty acid uptake, enhanced CD36 ubiquitination degradation was found in enterocytes upon SOAT2 inhibition. Insufficient free cholesterol esterification promoted endoplasmic reticulum stress and recruitment of E3 ligase RNF5 to activate CD36 ubiquitination in SOAT2 knockdown enterocytes. This work demonstrates a potential modulatory function of intestinal SOAT2 on lipid uptake highlighting the therapeutic effect on obesity by targeting intestinal SOAT2, exhibiting promising translational relevance in the siRNA therapeutic–based treatment for obesity. [ABSTRACT FROM AUTHOR]

Tuning immune‐cold tumor hot has largely attracted attention to improve cancer treatment, including immunotherapy and antibody‐drug conjugates (ADCs). Utilizing multiomic analyses and experimental validation, this work identifies a pivotal role for the USP10/B7‐H4 proteolytic axis in mediating the interplay between tumor immune responses and ADC efficacy, particularly for sacituzumab govitecan (SG) in treating triple negative breast cancers (TNBCs). Mechanistically, the inhibition of autocrine motility factor receptor (AMFR)‐mediated ubiquitylation of B7‐H4 by the deubiquitinase USP10 leads to the stabilization of B7‐H4, which suppresses tumor immune activity and reduces SG treatment effectiveness. Pharmacological inhibition of USP10 promotes the degradation of B7‐H4, enhancing tumor immunogenicity and consequently improving the tumor‐killing efficacy of SG. In preclinical TNBC models, suppression of USP10/B7‐H4 proteolytic axis is effective in increasing SG killing efficacy and reducing tumor growth, especially for the tumors with the USP10high/B7‐H7high signature. Collectively, these findings uncover a novel strategy for targeting the immunosuppressive molecule B7‐H4 for cancer therapy. [ABSTRACT FROM AUTHOR]

Posttranslational modifications (PTMs) such as phosphorylation, ubiquitination, SUMOylation, and ISGylation are involved in various cellular pathways, including innate immunity and disease processes. Many viruses have developed sophisticated mechanisms to modulate these host PTMs, either by inhibiting the interferon pathway or by enhancing the stability and function of viral proteins essential for replication. In this Pearl, we review the literature on how flaviviruses are impacted by and exploit posttranslational modifications to their advantage. [ABSTRACT FROM AUTHOR]

The objective was to determine whether USP13 stabilizes WISP1 protein and contributes to tumorigenicity and metastasis in ESCC through the Wnt/CTNNB1 signaling pathway. ESCC cell lines (KYSE150 and TE10) were treated with the proteasome inhibitor MG‐132, followed by siRNA screening of deubiquitinases (DUBs) to identify regulators of WISP1. Mass spectrometry, immunoprecipitation, and in vitro functional assays were conducted to explore the interaction between USP13 and WISP1 and to assess the effects of USP13 downregulation on cell proliferation, migration, invasion, epithelial–mesenchymal transition (EMT), and apoptosis. Additionally, in vivo experiments using mouse models were performed to evaluate the impact of USP13 knockdown on tumor growth and metastasis. USP13 was identified as a key regulator of WISP1, stabilizing its protein levels through deubiquitination. Downregulation of USP13 resulted in reduced WISP1 protein stability, decreased cell proliferation, migration, and EMT, and increased apoptosis in vitro. In vivo, USP13 knockdown significantly inhibited tumor growth and lung metastasis. WISP1 overexpression in USP13‐knockdown cells partially rescued these phenotypes, confirming the functional role of the USP13/WISP1 axis. Furthermore, knockdown of USP13 or WISP1 impaired the activation of the Wnt/CTNNB1 signaling pathway and reduced immune checkpoint marker expression, indicating a mechanism by which USP13 promotes immune evasion in ESCC. USP13 stabilizes WISP1 through deubiquitination, enhancing ESCC progression by activating the Wnt/CTNNB1 pathway and promoting immune evasion, making USP13 a potential therapeutic target in ESCC. [ABSTRACT FROM AUTHOR]

Melanosomes play a pivotal role in skin color and photoprotection. In contrast to the well-elucidated pathway of melanosome biogenesis, the process of melanosome degradation, referred to as melanophagy, is largely unexplored. Previously, we discovered that 3,4,5-trimethoxycinnamate thymol ester (TCTE) effectively inhibits skin pigmentation by activating melanophagy. In this study, we discovered a new regulatory signaling cascade that controls melanophagy in TCTE-treated melanocytes. ITCH (itchy E3 ubiquitin protein ligase) facilitates ubiquitination of the melanosome membrane protein MLANA (melan-A) during TCTE-induced melanophagy. This ubiquitinated MLANA is then recognized by an autophagy receptor protein, OPTN (optineurin). Additionally, a phospho-kinase antibody array revealed that TCTE activates PTK2 (protein tyrosine kinase 2), which phosphorylates ITCH, enhancing the ubiquitination of MLANA. Furthermore, inhibition of either PTK2 or ITCH disrupts the ubiquitination of MLANA and the MLANA-OPTN interaction in TCTE-treated cells. Taken together, our findings highlight the critical role of the PTK2-ITCH-MLANA-OPTN cascade in orchestrating melanophagy progression.Abbreviations: α-MSH: alpha-melanocyte-stimulating hormone; dichlone: 2,3-dichloro-1,4-naphthoquinone; ITCH: itchy E3 ubiquitin protein ligase; MITF: melanocyte inducing transcription factor; MLANA: melan-A; NBR1: NBR1 autophagy cargo receptor; OPTN: optineurin; PINK1: PTEN induced kinase 1; PTK2: protein tyrosine kinase 2; SQSTM1/p62: sequestosome 1; TCTE: 3,4,5-trimethoxycinnamate thymol ester; TPC2: two pore segment channel 2; VDAC1: voltage dependent anion channel 1. [ABSTRACT FROM AUTHOR]

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

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

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

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