TRIM/RBCC, a novel class of 'single protein RING finger' E3 ubiquitin ligases

TRIM59 deficiency promotes M1 macrophage activation and inhibits colorectal cancer through the STAT1 signaling pathway

Tumor-associated macrophages play a crucial role in the tumor microenvironment. Tripartite motif 59 (TRIM59), a member of the tripartite motif (TRIM) family, is known to be associated with immunological diseases and macrophage activation. The functional and molecular mechanisms by which TRIM59 affects the occurrence and development of colorectal cancer (CRC) through macrophages are still not well understood. To address this, we generated macrophage-specific TRIM59 conditional knockout mice and utilized these mice to establish colitis-associated cancer and MC38 transplanted CRC models for further investigation. We found that the deficiency of TRIM59 in macrophages inhibited colorectal tumorigenesis in mice. This tumor-suppressive effect was achieved by promoting the activation of M1 macrophages via STAT1 signaling pathway. Further mechanistic studies revealed that TRIM59 could regulate macrophage polarization by ubiquitinating and degrading STAT1. These findings provide evidence that TRIM59 deficiency promotes M1 macrophage activation and inhibits CRC through the STAT1 signaling pathway, suggesting that the TRIM59/STAT1 signaling pathway may be a promising target for CRC.

Molecular mechanism of TRIM32 in antiviral immunity in rainbow trout (Oncorhynchus mykiss)

TRIM family proteins are widely found in multicellular organisms and are involved in a wide range of life activities, and also act as crucial regulators in the antiviral natural immune response. This study aimed to reveal the molecular mechanism of rainbow trout TRIM protein in the anti-IHNV process. The results demonstrated that 99.1% homology between the rainbow trout and the chinook salmon (Oncorhynchus tshawytscha) TRIM32. When rainbow trout were infected with IHNV, the TRIM32 was highly expressed in the gill, spleen, kidney and blood. Meanwhile, rainbow trout TRIM32 has E3 ubiquitin ligase activity and undergoes K29-linked polyubiquitination modifications dependent on the RING structural domain was determined by immunoprecipitation. TRIM32 could interact with the NV protein of IHNV and degrade NV protein through the ubiquitin-proteasome pathway, and was also able to activate NF-κB transcription, thereby inhibiting the replication of IHNV. Moreover, the results of the animal studies showed that the survival rate of rainbow trout overexpressing TRIM32 was 70.2% which was significantly higher than that of the control group, and stimulating the body to produce high levels of IgM when the host was infected with the virus. In addition, TRIM32 can activate the NF-κB signalling pathway and participate in the antiviral natural immune response. The results of this study will help us to understand the molecular mechanism of TRIM protein resistance in rainbow trout, and provide new ideas for disease resistance breeding, vaccine development and immune formulation development in rainbow trout.

An investigation of the molecular characterization of the tripartite motif (TRIM) family and primary validation of TRIM31 in gastric cancer

Most TRIM family members characterized by the E3-ubiquitin ligases, participate in ubiquitination and tumorigenesis. While there is a dearth of a comprehensive investigation for the entire family in gastric cancer (GC). By combining the TCGA and GEO databases, common TRIM family members (TRIMs) were obtained to investigate gene expression, gene mutations, and clinical prognosis. On the basis of TRIMs, a consensus clustering analysis was conducted, and a risk assessment system and prognostic model were developed. Particularly, TRIM31 with clinical prognostic and diagnostic value was chosen for single-gene bioinformatics analysis, in vitro experimental validation, and immunohistochemical analysis of clinical tissue microarrays. The combined dataset consisted of 66 TRIMs, of which 52 were differentially expressed and 43 were differentially prognostic. Significant survival differences existed between the gene clusters obtained by consensus clustering analysis. Using 4 differentially expressed genes identified by multivariate Cox regression and LASSO regression, a risk scoring system was developed. Higher risk scores were associated with a poorer prognosis, suppressive immune cell infiltration, and drug resistance. Transcriptomic data and clinical sample tissue microarrays confirmed that TRIM31 was highly expressed in GC and associated with a poor prognosis. Pathway enrichment analysis, cell migration and colony formation assay, EdU assay, reactive oxygen species (ROS) assay, and mitochondrial membrane potential assay revealed that TRIM31 may be implicated in cell cycle regulation and oxidative stress-related pathways, contribute to gastric carcinogenesis. This study investigated the whole functional and expression profile and a risk score system based on the TRIM family in GC. Further investigation centered around TRIM31 offers insight into the underlying mechanisms of action exhibited by other members of its family in the context of GC.

Interleukin 27, Similar to Interferons, Modulates Gene Expression of Tripartite Motif (TRIM) Family Members and Interferes with Mayaro Virus Replication in Human Macrophages

BACKGROUND

The Tripartite motif (TRIM) family includes more than 80 distinct human genes. Their function has been implicated in regulating important cellular processes, including intracellular signaling, transcription, autophagy, and innate immunity. During viral infections, macrophages are key components of innate immunity that produce interferons (IFNs) and IL27. We recently published that IL27 and IFNs induce transcriptional changes in various genes, including those involved in JAK-STAT signaling. Furthermore, IL27 and IFNs share proinflammatory and antiviral pathways in monocyte-derived macrophages (MDMs), resulting in both common and unique expression of inflammatory factors and IFN-stimulated genes (ISGs) encoding antiviral proteins. Interestingly, many TRIM proteins have been recognized as ISGs in recent years. Although it is already very well described that TRIM expression is induced by IFNs, it is not fully understood whether TRIM genes are induced in macrophages by IL27. Therefore, in this study, we examined the effect of stimulation with IL27 and type I, II, and III IFNs on the mRNA expression profiles of TRIM genes in MDMs.

METHODS

We used bulk RNA-seq to examine the TRIM expression profile of MDMs treated with IFNs or IL27. Initially, we characterized the expression patterns of different TRIM subfamilies using a heatmap. Subsequently, a volcano plot was employed to identify commonly differentially expressed TRIM genes. Additionally, we conducted gene ontology analysis with ClueGO to explore the biological processes of the regulated TRIMs, created a gene-gene interaction network using GeneMANIA, and examined protein-protein interactions with the STRING database. Finally, RNA-seq data was validated using RT-qPCR. Furthermore, the effect of IL27 on Mayaro virus replication was also evaluated.

RESULTS

We found that IL27, similar to IFNs, upregulates several TRIM genes' expression in human macrophages. Specifically, we identified three common TRIM genes (TRIM19, 21, and 22) induced by IL27 and all types of human IFNs. Additionally, we performed the first report of transcriptional regulation of TRIM19, 21, 22, and 69 genes in response to IL27. The TRIMs involved a broad range of biological processes, including defense response to viruses, viral life cycle regulation, and negative regulation of viral processes. In addition, we observed a decrease in Mayaro virus replication in MDMs previously treated with IL27.

CONCLUSIONS

Our results show that IL27, like IFNs, modulates the transcriptional expression of different TRIM-family members involved in the induction of innate immunity and an antiviral response. In addition, the functional analysis demonstrated that, like IFN, IL27 reduced Mayaro virus replication in MDMs. This implies that IL27 and IFNs share many similarities at a functional level. Moreover, identifying distinct TRIM groups and their differential expressions in response to IL27 provides new insights into the regulatory mechanisms underlying the antiviral response in human macrophages.

TRIM21 and Fc-engineered antibodies: decoding its complex antibody binding mode with implications for viral neutralization

TRIM21 is a pivotal effector in the immune system, orchestrating antibody-mediated responses and modulating immune signaling. In this comprehensive study, we focus on the interaction of TRIM21 with Fc engineered antibodies and subsequent implications for viral neutralization. Through a series of analytical techniques, including biosensor assays, mass photometry, and electron microscopy, along with structure predictions, we unravel the intricate mechanisms governing the interplay between TRIM21 and antibodies. Our investigations reveal that the TRIM21 capacity to recognize, bind, and facilitate the proteasomal degradation of antibody-coated viruses is critically dependent on the affinity and avidity interplay of its interactions with antibody Fc regions. We suggest a novel binding mechanism, where TRIM21 binding to one Fc site results in the detachment of PRYSPRY from the coiled-coil domain, enhancing mobility due to its flexible linker, thereby facilitating the engagement of the second site, resulting in avidity due to bivalent engagement. These findings shed light on the dual role of TRIM21 in antiviral immunity, both in recognizing and directing viruses for intracellular degradation, and demonstrate its potential for therapeutic exploitation. The study advances our understanding of intracellular immune responses and opens new avenues for the development of antiviral strategies and innovation in tailored effector functions designed to leverage TRIM21s unique binding mode.

Genome-Wide Analysis of BBX Gene Family in Three Medicago Species Provides Insights into Expression Patterns under Hormonal and Salt Stresses

BBX protein is a class of zinc finger transcription factors that have B-box domains at the N-terminus, and some of these proteins contain a CCT domain at the C-terminus. It plays an important role in plant growth, development, and metabolism. However, the expression pattern of BBX genes in alfalfa under hormonal and salt stresses is still unclear. In this study, we identified a total of 125 BBX gene family members by the available Medicago reference genome in diploid alfalfa (Medicago sativa spp. Caerulea), a model plant (M. truncatula), and tetraploid alfalfa (M. sativa), and divided these members into five subfamilies. We found that the conserved motifs of BBXs of the same subfamily reveal similarities. We analyzed the collinearity relationship and duplication mode of these BBX genes and found that the expression pattern of BBX genes is specific in different tissues. Analysis of the available transcriptome data suggests that some members of the BBX gene family are involved in multiple abiotic stress responses, and the highly expressed genes are often clustered together. Furthermore, we identified different expression patterns of some BBX genes under salt, ethylene, salt and ethylene, salicylic acid, and salt and salicylic acid treatments, verified by qRT-PCR, and analyzed the subcellular localization of MsBBX2, MsBBX17, and MsBBX32 using transient expression in tobacco. The results showed that BBX genes were localized in the nucleus. This study systematically analyzed the BBX gene family in Medicago plants, which provides a basis for the study of BBX gene family tolerance to abiotic stresses.

Advances in nuclear proteostasis of metazoans

The proteostasis network and associated protein quality control (PQC) mechanisms ensure proteome functionality and are essential for cell survival. A distinctive feature of eukaryotic cells is their high degree of compartmentalization, requiring specific and adapted proteostasis networks for each compartment. The nucleus, essential for maintaining the integrity of genetic information and gene transcription, is one such compartment. While PQC mechanisms have been investigated for decades in the cytoplasm and the endoplasmic reticulum, our knowledge of nuclear PQC pathways is only emerging. Recent developments in the field have underscored the importance of spatially managing aberrant proteins within the nucleus. Upon proteotoxic stress, misfolded proteins and PQC effectors accumulate in various nuclear membrane-less organelles. Beyond bringing together effectors and substrates, the biophysical properties of these organelles allow novel PQC functions. In this review, we explore the specificity of the nuclear compartment, the effectors of the nuclear proteostasis network, and the PQC roles of nuclear membrane-less organelles in metazoans.

MG53/TRIM72: multi-organ repair protein and beyond

MG53, a member of the tripartite motif protein family, possesses multiple functionalities due to its classic membrane repair function, anti-inflammatory ability, and E3 ubiquitin ligase properties. Initially recognized for its crucial role in membrane repair, the therapeutic potential of MG53 has been extensively explored in various diseases including muscle injury, myocardial damage, acute lung injury, and acute kidney injury. However, further research has revealed that the E3 ubiquitin ligase characteristics of MG53 also contribute to the pathogenesis of certain conditions such as diabetic cardiomyopathy, insulin resistance, and metabolic syndrome. Moreover, recent studies have highlighted the anti-tumor effects of MG53 in different types of cancer, such as small cell lung cancer, liver cancer, and colorectal cancer; these effects are closely associated with their E3 ubiquitin ligase activities. In summary, MG53 is a multifunctional protein that participates in important physiological and pathological processes of multiple organs and is a promising therapeutic target for various human diseases. MG53 plays a multi-organ protective role due to its membrane repair function and its exertion of anti-tumor effects due to its E3 ubiquitin ligase properties. In addition, the controversial aspect of MG53's E3 ubiquitin ligase properties potentially causing insulin resistance and metabolic syndrome necessitates further cross-validation for clarity.

Swine acute diarrhea syndrome coronavirus nucleocapsid protein antagonizes the IFN response through inhibiting TRIM25 oligomerization and functional activation of RIG-I/TRIM25

Swine acute diarrhea syndrome coronavirus (SADS-CoV), an emerging Alpha-coronavirus, brings huge economic loss in swine industry. Interferons (IFNs) participate in a frontline antiviral defense mechanism triggering the activation of numerous downstream antiviral genes. Here, we demonstrated that TRIM25 overexpression significantly inhibited SADS-CoV replication, whereas TRIM25 deficiency markedly increased viral yield. We found that SADS-CoV N protein suppressed interferon-beta (IFN-β) production induced by Sendai virus (SeV) or poly(I:C). Moreover, we determined that SADS-CoV N protein interacted with RIG-I N-terminal two caspase activation and recruitment domains (2CARDs) and TRIM25 coiled-coil dimerization (CCD) domain. The interaction of SADS-CoV N protein with RIG-I and TRIM25 caused TRIM25 multimerization inhibition, the RIG-I-TRIM25 interaction disruption, and consequent the IRF3 and TBK1 phosphorylation impediment. Overexpression of SADS-CoV N protein facilitated the replication of VSV-GFP by suppressing IFN-β production. Our results demonstrate that SADS-CoV N suppresses the host IFN response, thus highlighting the significant involvement of TRIM25 in regulating antiviral immune defenses.

Novel oncogenic transcriptional targets of mutant p53 in esophageal squamous cell carcinoma

Missense mutations in the DNA binding domain of p53 are observed frequently in esophageal squamous cell carcinoma (ESCC). Recent studies have revealed the potentially oncogenic transcriptional networks regulated by mutant p53 proteins. However, majority of these studies have focused on common "hotspot" p53 mutations while rarer mutations are poorly characterized. In this study, we report the characterization of rare, "non-hotspot" p53 mutations from ESCC. In vitro tumorigenic assays performed following ectopic-expression of certain "non-hotspot" mutant p53 proteins caused enhancement of oncogenic properties in squamous carcinoma cell lines. Genome-wide transcript profiling of ESCC tumor samples stratified for p53 status, revealed several genes exhibiting elevated transcript levels in tumors harboring mutant p53. Of these, ARF6, C1QBP, and TRIM23 were studied further. Reverse transcription-quantitative PCR (RT-qPCR) performed on RNA isolated from ESCC tumors revealed significant correlation of TP53 transcript levels with those of the three target genes. Ectopic expression of wild-type and several mutant p53 forms followed by RT-qPCR, chromatin affinity-purification (ChAP), and promoter-luciferase assays indicated the exclusive recruitment of p53 mutants-P190T and P278L, to the target genes leading to the activation of expression. Several functional assays following knockdown of the target genes revealed a significant suppression of tumorigenicity in squamous carcinoma cell lines. Rescue experiments confirmed the specificity of the knockdown. The tumorigenic effects of the genes were confirmed in nude mice xenograft assays. This study has therefore identified novel oncogenic targets of "non-hotspot" mutant p53 proteins relevant for ESCC besides validating the functional heterogeneity of the spectrum of tumor-specific p53 mutations.

ISGylation of DRP1 closely balances other post-translational modifications to mediate mitochondrial fission

Dynamin related protein 1 (DRP1), a pivotal mitochondrial fission protein, is post-translationally modified by multiple mechanisms. Here we identify a new post-translational modification of DRP1 by the ubiquitin-like protein, interferon-stimulated gene 15 (ISG15). DRP1 ISGylation is mediated by ISG15 E3 ligase, HERC5; this promotes mitochondrial fission. DeISGylation of DRP1 however leads to hyperfusion. Heterologous expression of SARS-CoV2 PLpro, a deISGylating enzyme, results in similar mitochondrial filamentation, significant decrease in total DRP1 protein levels and efflux of mtDNA. We report that deISGylated DRP1 gets ubiquitylated and degraded by TRIM25, instead of PARKIN and MITOL. While the cytosolic pool of DRP1 is primarily ISGylated, both mitochondrial and cytosolic fractions may be ubiquitylated. It is known that phosphorylation of DRP1 at S616 residue regulates its mitochondrial localisation; we show that ISGylation of phospho-DRP1 (S616) renders fission competence at mitochondria. This is significant because DRP1 ISGylation affects its functionality and mitochondrial dynamics in Alzheimer's disease pathophysiology.

Identification of novel NRF2-dependent genes as regulators of lead and arsenic toxicity in neural progenitor cells

Lead (Pb) and arsenic (As) are prevalent metal contaminants in the environment. Exposures to these metals are associated with impaired neuronal functions and adverse effects on neurodevelopment in children. However, the molecular mechanisms by which Pb and As impair neuronal functions remain poorly understood. Here, we identified F2RL2, TRIM16L, and PANX2 as novel targets of Nuclear factor erythroid 2-related factor 2 (NRF2)-the master transcriptional factor for the oxidative stress response-that are commonly upregulated with both Pb and As in human neural progenitor cells (NPCs). Using a ChIP (Chromatin immunoprecipitation)-qPCR assay, we showed that NRF2 directly binds to the promoter region of F2RL2, TRIM16L, and PANX2 to regulate expression of these genes. We demonstrated that F2RL2, PANX2, and TRIM16L have differential effects on cell death, proliferation, and differentiation of NPCs in both the presence and absence of metal exposures, highlighting their roles in regulating NPC function. Furthermore, the analyses of the transcriptomic data on NPCs derived from autism spectrum disorder (ASD) patients revealed that dysregulation of F2RL2, TRIM16L, and PANX2 was associated with ASD genetic backgrounds and ASD risk genes. Our findings revealed that Pb and As induce a shared NRF2-dependent transcriptional response in NPCs and identified novel genes regulating NPC function. While further in vivo studies are warranted, this study provides a novel mechanism linking metal exposures to NPC function and identifies potential genes of interest in the context of neurodevelopment.

SUMO-3 promotes the ubiquitin-dependent turnover of TRIM55

Human muscle-specific RING fingers (MURFs) are members of the tripartite motif (TRIM) family of proteins characterized by their C-terminal subgroup one signature domain. MURFs play a role in sarcomere formation and microtubule dynamics. It was previously established that some TRIMs undergo post-translational modification by small ubiquitin-like modifier (SUMO). In this study, we explored the putative SUMOylation of MURF proteins as well as their interactions with SUMO. MURF proteins (TRIM54, TRIM55, and TRIM63) were not found to be SUMOylated. However, TRIM55 turnover by proteasomal and lysosomal degradation was higher upon overexpression of SUMO-3 but not of SUMO-1. Furthermore, it is predicted that TRIM55 contains two potential SUMO-interacting motifs (SIMs). We found that SIM1- and SIM2-mutated TRIM55 were more stable than the wild-type (WT) protein partly due to decreased degradation. Consistently, SIM-mutated TRIM55 was less polyubiquitinated than the WT protein, despite similar monoubiquitination levels. Using IF microscopy, we observed that SIM motifs influenced TRIM55 subcellular localization. In conclusion, our results suggest that SUMO-3 or SUMO-3-modified proteins modulate the localization, stability, and RING ubiquitin ligase activity of TRIM55.

Molecular mechanism governing RNA-binding property of mammalian TRIM71 protein

TRIM71 is an RNA-binding protein with ubiquitin ligase activity. Numerous functions of mammalian TRIM71, including cell cycle regulation, embryonic stem cell (ESC) self-renewal, and reprogramming of pluripotent stem cells, are related to its RNA-binding property. We previously reported that a long noncoding RNA (lncRNA) Trincr1 interacts with mouse TRIM71 (mTRIM71) to repress FGF/ERK pathway in mouse ESCs (mESCs). Herein, we identify an RNA motif specifically recognized by mTRIM71 from Trincr1 RNA, and solve the crystal structure of the NHL domain of mTRIM71 complexed with the RNA motif. Similar to the zebrafish TRIM71, mTRIM71 binds to a stem-loop structured RNA fragment of Trincr1, and an adenosine base at the loop region is crucial for the mTRIM71 interaction. We map similar hairpin RNAs preferably bound by TRIM71 in the mRNA UTRs of the cell-cycle related genes regulated by TRIM71. Furthermore, we identify key residues of mTRIM71, conserved among mammalian TRIM71 proteins, required for the RNA-binding property. Single-site mutations of these residues significantly impair the binding of TRIM71 to hairpin RNAs in vitro and to mRNAs of Cdkn1a/p21 and Rbl2/p130 in mESCs. Furthermore, congenital hydrocephalus (CH) specific mutation of mTRIM71 impair its binding to the RNA targets as well. These results reveal molecular mechanism behind the recognition of RNA by mammalian TRIM71 and provide insights into TRIM71 related diseases.

Suppression of protein quality control system by TRIM30a sensitises tumour cells to NK cell-mediated immune surveillance

Tumorigenesis entails circumventing cell-intrinsic regulatory mechanisms while avoiding extrinsic immune surveillance and other host defence systems. Nevertheless, how tumour cells' ability to eliminate misfolded proteins affects immune surveillance remains poorly understood. In this study, we find that overexpression of murine tripartite motif-containing protein 30a (TRIM30a) sensitises tumour cells to natural killer (NK) cells-mediated cytolysis. TRIM30a has no effect on tumour cell proliferation or apoptosis in vitro. However, TRIM30a-overexpressing tumour cells grow substantially slower than control tumour cells in immune-competent mice but not in NK cell-depleted mice. [Correction added on 04 October 2023, after first online publication: 'NK-depleted' has been changed to 'NK cell-depleted' in the preceding sentence.] Mechanistically, TRIM30a overexpression impedes the clearance of misfolded proteins and increases the production of reactive oxygen species induced by proteotoxic stress, implying that TRIM30a impairs protein quality control (PQC) systems in tumour cells. Furthermore, TRIM30a reduces expression of genes encoding proteasome subunits and antioxidant proteins. Our study demonstrates that TRIM30a is a potential tumour suppressor and immune modulator that promotes tumour cytolysis by NK cells, and suggests that an enhanced PQC and antioxidant capacity is an integral part of the immune escape mechanism during tumorigenesis.

Ubiquitin ligase enzymes and de-ubiquitinating enzymes regulate innate immunity in the TLR, NLR, RLR, and cGAS-STING pathways

Ubiquitination (or ubiquitylation) and de-ubiquitination, which are both post-translational modifications (PTMs) of proteins, have become a research hotspot in recent years. Some ubiquitinated or de-ubiquitinated signaling proteins have been found to promote or suppress innate immunity through Toll-like receptor (TLR), RIG-like receptor (RIG-I-like receptor, RLR), NOD-like receptor (NLR), and the cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase (cGAS)-STING pathway. This article aimed to provide a review on the role of ubiquitination and de-ubiquitination, especially ubiquitin ligase enzymes and de-ubiquitinating enzymes, in the above four pathways. We hope that our work can contribute to the research and development of treatment strategies for innate immunity-related diseases such as inflammatory bowel disease.

Intricate confrontation: Research progress and application potential of TRIM family proteins in tumor immune escape

BACKGROUND

Tripartite motif (TRIM) family proteins have more than 80 members and are widely found in various eukaryotic cells. Most TRIM family proteins participate in the ubiquitin-proteasome degradation system as E3-ubiquitin ligases; therefore, they play pivotal regulatory roles in the occurrence and development of tumors, including tumor immune escape. Due to the diversity of functional domains of TRIM family proteins, they can extensively participate in multiple signaling pathways of tumor immune escape through different substrates. In current research and clinical contexts, immune escape has become an urgent problem. The extensive participation of TRIM family proteins in curing tumors or preventing postoperative recurrence and metastasis makes them promising targets.

AIM OF REVIEW

The aim of the review is to make up for the gap in the current research on TRIM family proteins and tumor immune escape and propose future development directions according to the current progress and problems.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This up-to-date review summarizes the characteristics and biological functions of TRIM family proteins, discusses the mechanisms of TRIM family proteins involved in tumor immune escape, and highlights the specific mechanism from the level of structure-function-molecule-pathway-phenotype, including mechanisms at the level of protein domains and functions, at the level of molecules and signaling pathways, and at the level of cells and microenvironments. We also discuss the application potential of TRIM family proteins in tumor immunotherapy, such as possible treatment strategies for combination targeting TRIM family protein drugs and checkpoint inhibitors for improving cancer treatment.

Is MG53 a potential therapeutic target for cancer?

Cancer treatment still encounters challenges, such as side effects and drug resistance. The tripartite-motif (TRIM) protein family is widely involved in regulation of the occurrence, development, and drug resistance of tumors. MG53, a member of the TRIM protein family, shows strong potential in cancer therapy, primarily due to its E3 ubiquitin ligase properties. The classic membrane repair function and anti-inflammatory capacity of MG53 may also be beneficial for cancer prevention and treatment. However, MG53 appears to be a key regulatory factor in impaired glucose metabolism and a negative regulatory mechanism in muscle regeneration that may have a negative effect on cancer treatment. Developing MG53 mutants that balance the pros and cons may be the key to solving the problem. This article aims to summarize the role and mechanism of MG53 in the occurrence, progression, and invasion of cancer, focusing on the potential impact of the biological function of MG53 on cancer therapy.

Structure and activation of the RING E3 ubiquitin ligase TRIM72 on the membrane

Defects in plasma membrane repair can lead to muscle and heart diseases in humans. Tripartite motif-containing protein (TRIM)72 (mitsugumin 53; MG53) has been determined to rapidly nucleate vesicles at the site of membrane damage, but the underlying molecular mechanisms remain poorly understood. Here we present the structure of Mus musculus TRIM72, a complete model of a TRIM E3 ubiquitin ligase. We demonstrated that the interaction between TRIM72 and phosphatidylserine-enriched membranes is necessary for its oligomeric assembly and ubiquitination activity. Using cryogenic electron tomography and subtomogram averaging, we elucidated a higher-order model of TRIM72 assembly on the phospholipid bilayer. Combining structural and biochemical techniques, we developed a working molecular model of TRIM72, providing insights into the regulation of RING-type E3 ligases through the cooperation of multiple domains in higher-order assemblies. Our findings establish a fundamental basis for the study of TRIM E3 ligases and have therapeutic implications for diseases associated with membrane repair.

Tumor-specific GPX4 degradation enhances ferroptosis-initiated antitumor immune response in mouse models of pancreatic cancer

Lipid peroxidation-dependent ferroptosis has become an emerging strategy for tumor therapy. However, current strategies not only selectively induce ferroptosis in malignant cells but also trigger ferroptosis in immune cells simultaneously, which can compromise anti-tumor immunity. Here, we used In-Cell Western assays combined with an unbiased drug screening to identify the compound N6F11 as a ferroptosis inducer that triggered the degradation of glutathione peroxidase 4 (GPX4), a key ferroptosis repressor, specifically in cancer cells. N6F11 did not cause the degradation of GPX4 in immune cells, including dendritic, T, natural killer, and neutrophil cells. Mechanistically, N6F11 bound to the RING domain of E3 ubiquitin ligase tripartite motif containing 25 (TRIM25) in cancer cells to trigger TRIM25-mediated K48-linked ubiquitination of GPX4, resulting in its proteasomal degradation. Functionally, N6F11 treatment caused ferroptotic cancer cell death that initiated HMGB1-dependent antitumor immunity mediated by CD8+ T cells. N6F11 also sensitized immune checkpoint blockade that targeted CD274/PD-L1 in advanced cancer models, including genetically engineered mouse models of pancreatic cancer driven by KRAS and TP53 mutations. These findings may establish a safe and efficient strategy to boost ferroptosis-driven antitumor immunity.

Deciphering roles of TRIMs as promising targets in hepatocellular carcinoma: current advances and future directions

Tripartite motif (TRIM) family is assigned to RING-finger-containing ligases harboring the largest number of proteins in E3 ubiquitin ligating enzymes. E3 ubiquitin ligases target the specific substrate for proteasomal degradation via the ubiquitin-proteasome system (UPS), which seems to be a more effective and direct strategy for tumor therapy. Recent advances have demonstrated that TRIM genes associate with the occurrence and progression of hepatocellular carcinoma (HCC). TRIMs trigger or inhibit multiple biological activities like proliferation, apoptosis, metastasis, ferroptosis and autophagy in HCC dependent on its highly conserved yet diverse structures. Remarkably, autophagy is another proteolytic pathway for intracellular protein degradation and TRIM proteins may help to delineate the interaction between the two proteolytic systems. In depth research on the precise molecular mechanisms of TRIM family will allow for targeting TRIM in HCC treatment. We also highlight several potential directions warranted further development associated with TRIM family to provide bright insight into its translational values in hepatocellular carcinoma.

The role of TRIM family in metabolic associated fatty liver disease

Metabolic associated fatty liver disease (MAFLD) ranks among the most prevalent chronic liver conditions globally. At present, the mechanism of MAFLD has not been fully elucidated. Tripartite motif (TRIM) protein is a kind of protein with E3 ubiquitin ligase activity, which participates in highly diversified cell activities and processes. It not only plays an important role in innate immunity, but also participates in liver steatosis, insulin resistance and other processes. In this review, we focused on the role of TRIM family in metabolic associated fatty liver disease. We also introduced the structure and functions of TRIM proteins. We summarized the TRIM family's regulation involved in the occurrence and development of metabolic associated fatty liver disease, as well as insulin resistance. We deeply discussed the potential of TRIM proteins as targets for the treatment of metabolic associated fatty liver disease.

Role of the tripartite motif (TRIM) family in female genital neoplasms

The tripartite motif proteins (TRIMs) family represents a class of highly conservative proteins which play a large regulatory role in molecular processes. Recently, increasing evidence has demonstrated a role of TRIMs in female genital neoplasms. Our review thereby aimed to provide an overview of the biological involvement of TRIMs in female genital neoplasms, to provide a better understanding of its role in the development and progression of such diseases, and emphasize its potential as targeted cancer therapy. Overall, our review highlighted that the wide-ranging roles of TRIMs, in not only target protein ubiquitination, tumor migration and/or invasion, epithelial-mesenchymal transition, stemness, cell adhesion, proliferation, cell cycle regulation, and apoptosis, but also in influencing estrogenic, and chemotherapy response.

USP25 promotes hepatocellular carcinoma progression by interacting with TRIM21 via the Wnt/β-catenin signaling pathway

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world. The ubiquitin-specific peptidase 25 (USP25) protein has been reported to participate in the development of several cancers. However, few studies have reported its association with HCC. In this study, we aimed to investigate the function and mechanism of USP25 in the progression of HCC.

METHODS

We analyzed USP25 protein expression in HCC based on The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) database cohorts. Then, we constructed USP25-overexpressing and USP25-knockdown HepG2, MHCC97H, and L-O2 cells. We detected the biological function of USP25 by performing a series of assays, such as Cell Counting Kit-8 (CCK-8), colony formation, transwell, and wound healing assays. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) analyses were performed to detect the interaction between USP25 and the Wnt/β-catenin signaling pathway. The relationship between USP25 and tripartite motif-containing 21 (TRIM21) was assessed through mass spectrometry and co-immunoprecipitation (Co-IP) analysis. Finally, we constructed a mouse liver cancer model with the USP25 gene deletion to verify in vivo role of USP25.

RESULTS

USP25 was highly expressed in HCC tissue and HCC cell lines. Importantly, high expression of USP25 in tissues was closely related to a poor prognosis. USP25 knockdown markedly reduced the proliferation, migration, and invasion of HepG2 and MHCC97H cells, whereas USP25 overexpression led to the opposite effects. In addition, we demonstrated that USP25 interacts with TRIM21 to regulate the expression of proteins related to epithelial-mesenchymal transition (EMT; E-cadherin, N-cadherin, and Snail) and the Wnt/β-catenin pathway (β-catenin, Adenomatous polyposis coli, Axin2 and Glycogen synthase kinase 3 beta) and those of their downstream proteins (C-myc and Cyclin D1). Finally, we verified that knocking out USP25 inhibited tumor growth and distant metastasis in vivo .

CONCLUSIONS

In summary, our data showed that USP25 was overexpressed in HCC. USP25 promoted the proliferation, migration, invasion, and EMT of HCC cells by interacting with TRIM21 to activate the β-catenin signaling pathway.

The Molecular and Function Characterization of Porcine MID2

Midline2 (MID2/TRIM1) is a member of the tripartite motif-containing (TRIM) family, which is involved in a wide range of cellular processes. However, fundamental studies on porcine MID2 (pMID2) are still lacking. In this study, we identified and characterized the full length MID2 gene of pig (Sus scrofa). The sequence alignment analysis results showed that pMID2 had an N-terminal RING zinc-finger domain, BBC domain, and C-terminal COS box, FN3 motif, and PRY-SPRY domain that were conserved and similar to those of other vertebrates. Furthermore, pMID2 had the highest expression levels in porcine lung and spleen. Serial deletion and site-directed mutagenesis showed that the putative nuclear factor-κB (NF-κB) binding site may be an essential transcription factor for regulating the transcription expression of pMID2. Furthermore, the immunofluorescence assay indicated that pMID2 presented in the cell membrane and cytoplasm. To further study the functions of pMID2, we identified and determined its potential ability to perceive poly (I:C) and IFN-α stimulation. Stimulation experiments showed pMID2 enhanced poly (I:C)-/IFN-α-induced JAK-STAT signaling pathway, indicating that pMID2 might participate in the immune responses. In conclusion, we systematically and comprehensively analyzed the characterizations and functions of pMID2, which provide valuable information to explore the pMID2 functions in innate immunity. Our findings not only enrich the current knowledge of MID2 in IFN signaling regulation but also offer the basis for future research of pig MID2 gene.

Current progress on innate immune evasion mediated by Npro protein of pestiviruses

Interferon (IFN), the most effective antiviral cytokine, is involved in innate and adaptive immune responses and is essential to the host defense against virus invasion. Once the host was infected by pathogens, the pathogen-associated molecular patterns (PAMPs) were recognized by the host pattern recognition receptors (PRRs), which activates interferon regulatory transcription factors (IRFs) and nuclear factor-kappa B (NF-κB) signal transduction pathway to induce IFN expression. Pathogens have acquired many strategies to escape the IFN-mediated antiviral immune response. Pestiviruses cause massive economic losses in the livestock industry worldwide every year. The immune escape strategies acquired by pestiviruses during evolution are among the major difficulties in its control. Previous experiments indicated that Erns, as an envelope glycoprotein unique to pestiviruses with RNase activity, could cleave viral ss- and dsRNAs, therefore inhibiting the host IFN production induced by viral ss- and dsRNAs. In contrast, Npro, the other envelope glycoprotein unique to pestiviruses, mainly stimulates the degradation of transcription factor IRF-3 to confront the IFN response. This review mainly summarized the current progress on mechanisms mediated by Npro of pestiviruses to antagonize IFN production.

Genomic Analysis, Evolution and Characterization of E3 Ubiquitin Protein Ligase (TRIM) Gene Family in Common Carp (Cyprinus carpio)

Tripartite motifs (TRIM) is a large family of E3 ubiquitin ligases that play an important role in ubiquitylation. TRIM proteins regulate a wide range of biological processes from cellular response to viral infection and are implicated in various pathologies, from Mendelian disease to cancer. Although the TRIM family has been identified and characterized in tetrapods, but the knowledge about common carp and other teleost species is limited. The genes and proteins in the TRIM family of common carp were analyzed for evolutionary relationships, characterization, and functional annotation. Phylogenetic analysis was used to elucidate the evolutionary relationship of TRIM protein among teleost and higher vertebrate species. The results show that the TRIM orthologs of highly distant vertebrates have conserved sequences and domain architectures. The pairwise distance was calculated among teleost species of TRIMs, and the result exhibits very few mismatches at aligned position thus, indicating that the members are not distant from each other. Furthermore, TRIM family of common carp clustered into six groups on the basis of phylogenetic analysis. Additionally, the analysis revealed conserved motifs and functional domains in the subfamily members. The difference in functional domains and motifs is attributed to the evolution of these groups from different ancestors, thus validating the accuracy of clusters in the phylogenetic tree. However, the intron-exon organization is not precisely similar, which suggests duplication of genes and complex alternative splicing. The percentage of secondary structural elements is comparable for members of the same group, but the tertiary conformation is varied and dominated by coiled-coil segments required for catalytic activity. Gene ontology analysis revealed that these proteins are mainly associated with the catalytic activity of ubiquitination, immune system, zinc ion binding, positive regulation of transcription, ligase activity, and cell cycle regulation. Moreover, the biological pathway analyses identified four KEGG and 22 Reactome pathways. The predicted pathways correspond to functional domains, and gene ontology which proposes that proteins with similar structures might perform the same functions.

TRIM7 inhibits encephalomyocarditis virus replication by activating interferon-β signaling pathway

Tripartite motif-containing protein 7 (TRIM7), the member of tripartite motif (TRIM) family, plays an important role in innate immune responses against viral infection. Among them, the function of TRIM7 in Encephalomyocarditis virus (EMCV) infection has not been reported. Here, we found that TRIM7 inhibited the replication of EMCV through the type I interferon (IFN) signaling pathway. Interestingly, TRIM7 was down-regulated after EMCV infection in HEK293T cells. Further, overexpression of TRIM7 suppressed the replication of EMCV in HEK293T cells and enhanced the activity of IFN-β promoter. On the other hand, knockdown of the endogenous TRIM7 promoted EMCV infection and impaired the activity of IFN-β promoter. TRIM7 could regulate retinoic acid-inducible gene I (RIG-I)/ melanoma differentiation-associated gene 5 (MDA5)/ mitochondrial antiviral-signaling protein (MAVS) mediated IFN-β signaling pathway. Moreover, TRIM7 interacted with MAVS and they were co-located in HEK293T cells. We demonstrate that TRIM7 plays a positive role in IFN-β signaling pathway during EMCV infection and suppresses EMCV replication. Taken together, the presented results suggest that TRIM7 has a pivotal function in anti-EMCV infection, thereby providing a potential target for further development of anti-EMCV inhibitors.

NbMLP43 Ubiquitination and Proteasomal Degradation via the Light Responsive Factor NbBBX24 to Promote Viral Infection

The ubiquitin-proteasome system (UPS) plays an important role in virus-host interactions. However, the mechanism by which the UPS is involved in innate immunity remains unclear. In this study, we identified a novel major latex protein-like protein 43 (NbMLP43) that conferred resistance to Nicotiana benthamiana against potato virus Y (PVY) infection. PVY infection strongly induced NbMLP43 transcription but decreased NbMLP43 at the protein level. We verified that B-box zinc finger protein 24 (NbBBX24) interacted directly with NbMLP43 and that NbBBX24, a light responsive factor, acted as an essential intermediate component targeting NbMLP43 for its ubiquitination and degradation via the UPS. PVY, tobacco mosaic virus, (TMV) and cucumber mosaic virus (CMV) infections could promote NbMLP43 ubiquitination and proteasomal degradation to enhance viral infection. Ubiquitination occurred at lysine 38 (K38) within NbMLP43, and non-ubiquitinated NbMLP43(K38R) conferred stronger resistance to RNA viruses. Overall, our results indicate that the novel NbMLP43 protein is a target of the UPS in the competition between defense and viral anti-defense and enriches existing theoretical studies on the use of UPS by viruses to promote infection.

TRIM proteins in breast cancer: Function and mechanism

Breast cancer is the most prevalent malignancy in the world, and despite tremendous progress in current treatment strategies, recurrence, metastasis and drug resistance of breast cancer remain the major causes of death in patients. Tripartite motif (TRIM) family proteins play a critical role in the tumor progression such as cell proliferation, migration, invasion, and metastasis. Accumulating evidence suggests that the TRIM protein family serve as cancer suppressor proteins or oncoproteins in breast cancer. This review focused on the roles and molecular mechanisms of TRIM protein in breast cancer. Importantly, it provides new insights that TRIM proteins may be ideal targets to treat breast cancer.

Duck TRIM29 negatively regulates type I IFN production by targeting MAVS

The innate immune response is a host defense mechanism that induces type I interferon and proinflammatory cytokines. Tripartite motif (TRIM) family proteins have recently emerged as pivotal regulators of type I interferon production in mammals. Here, we first identified duck TRIM29, which encodes 571 amino acids and shows high sequence homology with other bird TRIM29 proteins. DuTRIM29 inhibited IFN-β and IRF7 promoter activation in a dose-dependent manner and downregulated the mRNA expression of IFN-β, IRF7, Mx and IL-6 mediated by duRIG-I. Moreover, duTRIM29 interacted and colocalized with duMAVS in the cytoplasm. DuTRIM29 interacted with duMAVS via its C-terminal domains. In addition, duTRIM29 inhibited IFN-β and IRF7 promoter activation and significantly downregulated IFN-β and immune-related gene expression mediated by duMAVS in ducks. Furthermore, duTRIM29 induced K29-linked polyubiquitination and degradation of duMAVS to suppress the expression of IFN-β. Overall, our results demonstrate that duTRIM29 negatively regulates type I IFN production by targeting duMAVS in ducks. This study will contribute to a better understanding of the molecular mechanism regulating the innate immune response by TRIM proteins in ducks.

Knockdown of TRIM8 alleviates dextran sulfate sodium-induced colitis in mice by inhibiting the NF-κB signaling pathway

BACKGROUND

Although TRIpartite Motif containing 8 (TRIM8) gene plays an important role in a number of biological processes, such as inflammation, its function and mechanism in ulcerative colitis (UC) remain unknown.

METHODS

The UC model was established by feeding mice with 3.5% dextran sulfate sodium (DSS). The animals were divided into the following four groups: control group, DSS group, DSS+short hairpin (sh)-NC group, and DSS+sh-TRIM8 group. Changes in body weight and disease activity index (DAI) score of mice in all the groups were recorded for 7 days. The animals were executed at the end of the experiment, and the expression of TRIM8 in colon tissue was detected by polymerase chain reaction and Western blot assays. The length of colon was measured, and the histopathological changes in mice colon were examined by hematoxylin and eosin staining. The expression of pro-inflammatory factors in mice serum and colonic tissue homogenate was detected by enzyme-linked-immunosorbent serologic assay. The expression of nuclear factor kappa B (NF-κB) pathway-related proteins in colonic tissues was detected by Western-blot analysis.

RESULTS

TRIM8 was highly expressed in the colonic tissues of UC mice. Knockdown of TRIM8 improved DSS-induced weight loss, increased DAI score, shortened colon length, and alleviated colonic injury and inflammation in mice. Western-blot experiments showed that knockdown of TRIM8 inhibited DSS-induced phosphorylation of p65 and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) protein but increased IκBα expression.

CONCLUSION

Knockdown of TRIM8 inhibits UC injury and inflammatory response caused by DSS. This could be related to the regulation of NF-κB signaling pathway by TRIM8 protein.

TRIM31: A molecule with a dual role in cancer

Tripartite motif (TRIM) 31 is a new member of the TRIM family and functions as an E3 ubiquitin ligase. Abnormal TRIM31 expression leads to a variety of pathological conditions, such as cancer, innate immunity diseases, sepsis-induced myocardial dysfunction, cerebral ischemic injury, nonalcoholic fatty liver disease and hypertensive nephropathy. In this review, we comprehensively overview the structure, expression and regulation of TRIM31 in cancer. Moreover, we discuss the dual role of TRIM31 in human cancer, and this dual role may be linked to its involvement in the selective regulation of several pivotal cellular signaling pathways: the p53 tumor suppressor, mTORC1, PI3K-AKT, NF-κB and Wnt/β-catenin pathways. In addition, we also discuss the emerging role of TRIM31 in innate immunity, autophagy and its growing sphere of influence across multiple human pathologies. Finally, a better understanding of the dual role of TRIM31 in cancer may provide new therapeutic strategies aimed at inhibiting the cancer-promoting effects of TRIM31 without affecting its tumor suppressor effects.

Divergent self-association properties of paralogous proteins TRIM2 and TRIM3 regulate their E3 ligase activity

Tripartite motif (TRIM) proteins constitute a large family of RING-type E3 ligases that share a conserved domain architecture. TRIM2 and TRIM3 are paralogous class VII TRIM members that are expressed mainly in the brain and regulate different neuronal functions. Here we present a detailed structure-function analysis of TRIM2 and TRIM3, which despite high sequence identity, exhibit markedly different self-association and activity profiles. We show that the isolated RING domain of human TRIM3 is monomeric and inactive, and that this lack of activity is due to a few placental mammal-specific amino acid changes adjacent to the core RING domain that prevent self-association but not E2 recognition. We demonstrate that the activity of human TRIM3 RING can be restored by substitution with the relevant region of human TRIM2 or by hetero-dimerization with human TRIM2, establishing that subtle amino acid changes can profoundly affect TRIM protein activity. Finally, we show that TRIM2 and TRIM3 interact in a cellular context via their filamin and coiled-coil domains, respectively.

TRIM56 promotes malignant progression of glioblastoma by stabilizing cIAP1 protein

BACKGROUND

The tripartite motif (TRIM) family of proteins plays a key role in the developmental growth and therapeutic resistance of many tumors. However, the regulatory mechanisms and biological functions of TRIM proteins in human glioblastoma (GBM) are not yet fully understood. In this study, we focused on TRIM56, which emerged as the most differentially expressed TRIM family member with increased expression in GBM.

METHODS

Western blot, real-time quantitative PCR (qRT-PCR), immunofluorescence (IF) and immunohistochemistry (IHC) were used to study the expression levels of TRIM56 and cIAP1 in GBM cell lines. Co-immunoprecipitation (co-IP) was used to explore the specific binding between target proteins and TRIM56. A xenograft animal model was used to verify the tumor promoting effect of TRIM56 on glioma in vivo.

RESULTS

We observed elevated expression of TRIM56 in malignant gliomas and revealed that TRIM56 promoted glioma progression in vitro and in a GBM xenograft model in nude mice. Analysis of the Human Ubiquitin Array and co-IPs showed that cIAP1 is a protein downstream of TRIM56. TRIM56 deubiquitinated cIAP1, mainly through the zinc finger domain (amino acids 21-205) of TRIM56, thereby reducing the degradation of cIAP1 and thus increasing its expression. TRIM56 also showed prognostic significance in overall survival of glioma patients.

CONCLUSIONS

TRIM56-regulated post-translational modifications may contribute to glioma development through stabilization of cIAP1. Furthermore, TRIM56 may serve as a novel prognostic indicator and therapeutic molecular target for GBM.

Regulation of Epstein-Barr Virus Minor Capsid Protein BORF1 by TRIM5α

TRIM5α is a host anti-retroviral restriction factor that destroys human immunodeficiency virus (HIV) virions and triggers innate immune signaling. TRIM5α also mediates the autophagic degradation of target proteins via TRIMosome formation. We previously showed that TRIM5α promotes Epstein-Barr virus (EBV) Rta ubiquitination and attenuates EBV lytic progression. In this study, we sought to elucidate whether TRIM5α can interact with and induce the degradation of EBV capsid proteins. Glutathione S-transferase (GST) pulldown and immunoprecipitation assays were conducted to identify interacting proteins, and mutants were generated to investigate key binding domains and ubiquitination sites. Results showed that TRIM5α binds directly with BORF1, an EBV capsid protein with a nuclear localization signal (NLS) that enables the transport of EBV capsid proteins into the host nucleus to facilitate capsid assembly. TRIM5α promotes BORF1 ubiquitination, which requires the surface patch region in the TRIM5α PRY/SPRY domain. TRIM5α expression also decreases the stability of BORF1(6KR), a mutant with all lysine residues mutated to arginine. However, chloroquine treatment restores the stability of BORF1(6KR), suggesting that TRIM5α destabilizes BORF1 via direct recognition of its substrate for autophagic degradation. These results reveal novel insights into the antiviral impact of TRIM5α beyond retroviruses.

Eight TRIM32 isoforms from oriental river prawn Macrobrachium nipponense are involved in innate immunity during white spot syndrome virus infection

Tripartite motif (TRIM) proteins comprise a large family of RING-type ubiquitin E3 ligases that regulate important biological processes. In this study, full-length MnTRIM32 cDNA was obtained from oriental river prawn Macrobrachium nipponense, and eight MnTRIM32 isoforms generated by alternative splicing were identified. The open reading frames of the eight MnTRIM32 isoforms were predicted to be separately composed of 402, 346, 347, 346, 414, 358, 359, and 358 amino acid residues. Protein structural analysis revealed that all MnTRIM32 isoforms contained a RING domain and a coiled coil region. MnTRIM32 was ubiquitously expressed in all tissues tested, with the highest expression in the hepatopancreas. The mRNA levels of MnTRIM32 in the gills, stomach, and intestine of prawns were found to undergo time-dependent enhancement following white spot syndrome virus (WSSV) stimulation. Double-stranded RNA interference studies revealed that MnTRIM32 silencing significantly downregulated the expression levels of interferon (IFN) regulatory factor MnIRF, IFN-like factor MnVago4, and tumor necrosis factor MnTNF. Furthermore, knockdown of MnTRIM32 in WSSV-challenged prawns increased the expression of VP28 and the number of WSSV copies, suggesting that MnTRIM32 plays a positive role in limiting WSSV infection. These findings provided strong evidence for the important role of MnTRIM32 in the antiviral innate immunity of M. nipponense.

Tripartite motif containing 23 functions as a critical regulator in macrophages to control the pathological feature of diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is a kidney disease resulting from diabetes. Macrophages and macrophage-mediated inflammation contributed to the development of DN. Tripartite motif containing 23 (TRIM23) is E3 ligase and has been involved in inflammation. Until now, the precise roles of TRIM23 in DN are not described yet. Therefore, we evaluated the functions of TRIM23 in DN.

METHODS

We generated mice with TRIM23 deficiency in macrophages. We also established diabetic mice model. The expression of TRIM23 was measured in diabetic animals. The DN symptoms were compared between diabetic wild-type (WT) mice and TRIM23 conditional knock out mice. The cytokine expression, ubiquitination of TAB2, and interactions between TAB2 and IKK were compared in oxidized low-density lipoprotein (oxLDL) or lipopolysaccharides (LPS)-treated WT and TRIM23-deficient macrophages.

RESULTS

Upregulation of TRIM23 was observed in diabetic mice and LPS or oxLDL-treated macrophages. Diabetic mice with TRIM23 deficiency in macrophages had attenuated DN symptoms. TRIM23-deficient macrophages had decreased pro-inflammatory cytokines production after oxLDL or LPS stimulation. TRIM23 was predicted to interact with TAB2. The ubiquitination of TAB2 was abolished in oxLDL-treated TRIM23-deficient macrophages, which correlated with decreased activation of IKK.

CONCLUSION

TRIM23 regulates inflammation in macrophages and plays important role in DN.

Interaction between chicken TRIM25 and MDA5 and their role in mediated antiviral activity against IBDV infection

Infectious Bursal Disease Virus (IBDV) is the causative agent of an immunosuppressive disease that affects domestic chickens (Gallus gallus) severely affecting poultry industry worldwide. IBDV infection is characterized by a rapid depletion of the bursal B cell population by apoptosis and the atrophy of this chief lymphoid organ. Previous results from our laboratory have shown that exposure of infected cells to type I IFN leads to an exacerbated apoptosis, indicating an important role of IFN in IBDV pathogenesis. It has been described that recognition of the dsRNA IBDV genome by MDA5, the only known cytoplasmic pattern recognition receptor for viral RNA in chickens, leads to type I IFN production. Here, we confirm that TRIM25, an E3 ubiquitin ligase that leads to RIG-I activation in mammalian cells, significantly contributes to positively regulate MDA5-mediated activation of the IFN-inducing pathway in chicken DF-1 cells. Ectopic expression of chTRIM25 together with chMDA5 or a deletion mutant version exclusively harboring the CARD domains (chMDA5 2CARD) enhances IFN-β and NF-ĸB promoter activation. Using co-immunoprecipitation assays, we show that chMDA5 interacts with chTRIM25 through the CARD domains. Moreover, chTRIM25 co-localizes with both chMDA5 and chMDA5 2CARD, but not with chMDA5 mutant proteins partially or totally lacking these domains. On the other hand, ablation of endogenous chTRIM25 expression reduces chMDA5-induced IFN-β and NF-ĸB promoter activation. Interestingly, ectopic expression of either wild-type chTRIM25, or a mutant version (chTRIM25 C59S/C62S) lacking the E3 ubiquitin ligase activity, restores the co-stimulatory effect of chMDA5 in chTRIM25 knockout cells, suggesting that the E3-ubiquitin ligase activity of chTRIM25 is not required for its downstream IFN-β and NF-ĸB activating function. Also, IBDV-induced expression of IFN-β, Mx and OAS genes was reduced in chTRIM25 knockout as compared to wild-type cells, hence contributing to the enhancement of IBDV replication. Enhanced permissiveness to replication of other viruses, such as avian reovirus, Newcastle disease virus and vesicular stomatitis virus was also observed in chTRIM25 knockout cells. Additionally, chTRIM25 knockout also results in reduced MAVS-induced IFN-β promoter stimulation. Nonetheless, similarly to its mammalian counterpart, chTRIM25 overexpression in wild-type DF-1 cells causes the degradation of ectopically expressed chMAVS.

E3 ubiquitin ligases in the acute leukemic signaling pathways

Acute leukemia is a common hematologic tumor with highly genetic heterogeneity, and many factors are involved in the pathogenesis and drug-resistance mechanism. Emerging evidence proves that E3 ubiquitin ligases participate in the acute leukemic signaling pathways via regulating substrates. This review summarized the E3 ligases which can affect the leukemic signal. It is worth noting that the abnormal signal is often caused by a deficiency or a mutation of the E3 ligases. In view of this phenomenon, we envisioned perspectives associated with targeted agonists of E3 ligases and proteolysis-targeting chimera technology. Moreover, we emphasized the significance of research into the upstream factors regulating the expression of E3 ubiquitin ligases. It is expected that the understanding of the mechanism of leukemic signaling pathways with which that E3 ligases are involved will be beneficial to accelerating the process of therapeutic strategy improvement for acute leukemia.

Trim39 regulates neuronal apoptosis by acting as a SUMO-targeted E3 ubiquitin-ligase for the transcription factor NFATc3

NFATc3 is the predominant member of the NFAT family of transcription factors in neurons, where it plays a pro-apoptotic role. Mechanisms controlling NFAT protein stability are poorly understood. Here we identify Trim39 as an E3 ubiquitin-ligase of NFATc3. Indeed, Trim39 binds and ubiquitinates NFATc3 in vitro and in cells where it reduces NFATc3 protein level and transcriptional activity. In contrast, silencing of endogenous Trim39 decreases NFATc3 ubiquitination and increases its activity, thereby resulting in enhanced neuronal apoptosis. We also show that Trim17 inhibits Trim39-mediated ubiquitination of NFATc3 by reducing both the E3 ubiquitin-ligase activity of Trim39 and the NFATc3/Trim39 interaction. Moreover, we identify Trim39 as a new SUMO-targeted E3 ubiquitin-ligase (STUbL). Indeed, mutation of SUMOylation sites in NFATc3 or SUMO-interacting motifs in Trim39 reduces NFATc3/Trim39 interaction and Trim39-induced ubiquitination of NFATc3. In addition, Trim39 preferentially ubiquitinates SUMOylated forms of NFATc3 in vitro. As a consequence, a SUMOylation-deficient mutant of NFATc3 exhibits increased stability and pro-apoptotic activity in neurons. Taken together, these data indicate that Trim39 modulates neuronal apoptosis by acting as a STUbL for NFATc3.

TRIM family contribute to tumorigenesis, cancer development, and drug resistance

The tripartite-motif (TRIM) family represents one of the largest classes of putative single protein RING-finger E3 ubiquitin ligases. TRIM family is involved in a variety of cellular signaling transductions and biological processes. TRIM family also contributes to cancer initiation, progress, and therapy resistance, exhibiting oncogenic and tumor-suppressive functions in different human cancer types. Moreover, TRIM family members have great potential to serve as biomarkers for cancer diagnosis and prognosis. In this review, we focus on the specific mechanisms of the participation of TRIM family members in tumorigenesis, and cancer development including interacting with dysregulated signaling pathways such as JAK/STAT, PI3K/AKT, TGF-β, NF-κB, Wnt/β-catenin, and p53 hub. In addition, many studies have demonstrated that the TRIM family are related to tumor resistance; modulate the epithelial–mesenchymal transition (EMT) process, and guarantee the acquisition of cancer stem cells (CSCs) phenotype. In the end, we havediscussed the potential of TRIM family members for cancer therapeutic targets.

Bag it, tag it: ubiquitin ligases and host resistance to Mycobacterium tuberculosis

Infection with Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis (TB), remains a significant global epidemic. Host resistance to Mtb depends on both adaptive and innate immunity mechanisms, including development of antigen-specific CD4 and CD8 T cells, production of inflammatory cytokines, bacterial phagocytosis and destruction within phagolysosomes, host cell apoptosis, and autophagy. A key regulatory mechanism in innate immunity is the attachment of the small protein ubiquitin to protein and lipid targets by the enzymatic activity of ubiquitin ligases. Here, we summarize the latest advances on the role of ubiquitination and ubiquitin ligases in host immunity against Mtb, with a focus on innate immunity signaling, inflammation, and antimicrobial autophagy. Understanding how ubiquitin ligases mediate immunity to Mtb, and the specific substrates of distinct ubiquitin ligases in the context of Mtb infection, could facilitate development of new host-directed antimicrobials.

Emerging Roles of TRIM Family Proteins in Gliomas Pathogenesis

Simple Summary

Gliomas remain challenging tumors due to their increased heterogeneity, complex molecular profile, and infiltrative phenotype that are often associated with a dismal prognosis. In a constant search for molecular changes and associated mechanisms, the TRIM protein family has emerged as an important area of investigation because of the regulation of vital cellular processes involved in brain pathophysiology that may possibly lead to brain tumor development. Herein, we discuss the diverse role of TRIM proteins in glioma progression, aiming to detect potential targets for future intervention.

Abstract

Gliomas encompass a vast category of CNS tumors affecting both adults and children. Treatment and diagnosis are often impeded due to intratumor heterogeneity and the aggressive nature of the more malignant forms. It is therefore essential to elucidate the molecular mechanisms and explore the intracellular signaling pathways underlying tumor pathology to provide more promising diagnostic, prognostic, and therapeutic tools for gliomas. The tripartite motif-containing (TRIM) superfamily of proteins plays a key role in many physiological cellular processes, including brain development and function. Emerging evidence supports the association of TRIMs with a wide variety of cancers, exhibiting both an oncogenic as well as a tumor suppressive role depending on cancer type. In this review, we provide evidence of the pivotal role of TRIM proteins in gliomagenesis and exploit their potential as prognostic biomarkers and therapeutic targets.

Cryo-EM structure of human MG53 homodimer

MG53 is a tripartite motif (TRIM) family E3 ligase and plays important biological functions. Here we present the cryo-EM structure of human MG53, showing that MG53 is a homodimer consisting of a "body" and two "wings". Intermolecular interactions are mainly distributed in the "body" which is relatively stable, while two "wings" are more dynamic. The overall architecture of MG53 is distinct from those of TRIM20 and TRIM25, illustrating the broad structural diversity of this protein family.

GNIP1 functions both as a scaffold protein and an E3 ubiquitin ligase to regulate autophagy in lung cancer

Background

Glycogen-Interacting Protein 1 (GNIP1), an E3 ligase, is a member of the tripartite motif (TRIM) family proteins. Current studies on GNIP1 mainly focus on glycogen metabolism. However, the function and molecular mechanisms of GNIP1 in regulating autophagy still remains unclear. This study aimed to investigate the regulatory mechanism of GNIP1 in regulating autophagy in non-small cell lung cancer (NSCLC).

Methods

Crystal violet staining assays were used to evaluate the ability of cell growth and proliferation. Transwell and scratch wound healing assays were used to evaluate the cell migration ability. The protein expressions were measured by western blot and immunohistochemistry. Co-immunoprecipitation assays determined the protein–protein interactions. The in vivo effect of GNIP1 on tumor growth was determined by xenograft assay.

Results

We found that GNIP1 was overexpressed in tumor tissues and the expression level of GNIP1 was related to the poor prognosis and the survival time of NSCLC patients. In non-small cell lung cancer (NSCLC), GNIP1 increased proliferation and migration of cancer cells by promoting autophagy. Mechanistic studies indicated that GNIP1, as a scaffold protein, recruited BECN1 and LC3B to promote the formation of autophagosomes. Besides, GNIP1 mediated the degradation of 14-3-3ζ, the negative regulator of VPS34 complex, thus promoting autophagy. Overexpressing GNIP1 promoted tumorigenesis and enhanced autophagy in xenograft models.

Conclusion

GNIP1 promotes proliferation and migration of NSCLC cells through mediating autophagy, which provides theoretical basis for targeting GNIP1 as anti-cancer drugs.

RING-finger E3 ligases regulatory network in PI3K/AKT-mediated glucose metabolism

The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway plays an essential role in glucose metabolism, promoting glycolysis and resisting gluconeogenesis. PI3K/AKT signaling can directly alter glucose metabolism by phosphorylating several metabolic enzymes or regulators of nutrient transport. It can indirectly promote sustained aerobic glycolysis by increasing glucose transporters and glycolytic enzymes, which are mediated by downstream transcription factors. E3 ubiquitin ligase RING-finger proteins are mediators of protein post-translational modifications and include the cullin-RING ligase complexes, the tumor necrosis factor receptor-associated family, the tripartite motif family and etc. Some members of the RING family play critical roles in regulating cell signaling and are involved in the development and progression of various metabolic diseases, such as cancer, diabetes, and dyslipidemia. And with the progression of modern research, as a negative or active regulator, the RING-finger adaptor has been found to play an indispensable role in PI3K/AKT signaling. However, no reviews have comprehensively clarified the role of RING-finger E3 ligases in PI3K/AKT-mediated glucose metabolism. Therefore, in this review, we focus on the regulation and function of RING ligases in PI3K/AKT-mediated glucose metabolism to establish new insights into the prevention and treatment of metabolic diseases.

Expression and Role of TRIM2 in Human Diseases

Tripartite motif (TRIM) protein family proteins contain more than 80 members in humans, and most of these proteins exhibit E3 ubiquitin ligase activity mediated through a RING finger domain. Their biological functions are very complex, and they perform diverse functions in cell evolution processes, such as intracellular signaling, development, apoptosis, protein quality control, innate immunity, autophagy, and carcinogenesis. Tripartite motif-containing protein 2 (TRIM2), a member of the TRIM superfamily, is an 81 kDa multidomain protein, also known as CMT2R or RNF86, located at 4q31.3. TRIM2 functions as an E3 ubiquitin ligase. Current studies have shown that TRIM2 can play roles in neuroprotection, neuronal rapid ischemic tolerance, antiviral responses, neurological diseases, etc. Moreover, based on some studies in tumors, TRIM2 regulates tumor proliferation, migration, invasion, apoptosis, and drug resistance through different mechanisms and plays a critical role in tumor occurrence and development. This review is aimed at providing a systematic and comprehensive summary of research on TRIM2 and at exploring the potential role of TRIM2 as a biomarker and therapeutic target in many kinds of human diseases.

TRIM family proteins: roles in proteostasis and neurodegenerative diseases

Neurodegenerative diseases (NDs) are a diverse group of disorders characterized by the progressive degeneration of the structure and function of the central or peripheral nervous systems. One of the major features of NDs, such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD), is the aggregation of specific misfolded proteins, which induces cellular dysfunction, neuronal death, loss of synaptic connections and eventually brain damage. By far, a great amount of evidence has suggested that TRIM family proteins play crucial roles in the turnover of normal regulatory and misfolded proteins. To maintain cellular protein quality control, cells rely on two major classes of proteostasis: molecular chaperones and the degradative systems, the latter includes the ubiquitin-proteasome system (UPS) and autophagy; and their dysfunction has been established to result in various physiological disorders including NDs. Emerging evidence has shown that TRIM proteins are key players in facilitating the clearance of misfolded protein aggregates associated with neurodegenerative disorders. Understanding the different pathways these TRIM proteins employ during episodes of neurodegenerative disorder represents a promising therapeutic target. In this review, we elucidated and summarized the diverse roles with underlying mechanisms of members of the TRIM family proteins in NDs.