TRIM44 Promotes Rabies Virus Replication by Autophagy-Dependent Mechanism.

Tripartite motif (TRIM) proteins are a multifunctional E3 ubiquitin ligase family that participates in various cellular processes. Recent studies have shown that TRIM proteins play important roles in regulating host-virus interactions through specific pathways, but their involvement in response to rabies virus (RABV) infection remains poorly understood. Here, we identified that several TRIM proteins are upregulated in mouse neuroblastoma cells (NA) after infection with the rabies virus using RNA-seq sequencing. Among them, TRIM44 was found to regulate RABV replication. This is supported by the observations that downregulation of TRIM44 inhibits RABV replication, while overexpression of TRIM44 promotes RABV replication. Mechanistically, TRIM44-induced RABV replication is brought about by activating autophagy, as inhibition of autophagy with 3-MA attenuates TRIM44-induced RABV replication. Additionally, we found that inhibition of autophagy with rapamycin reverses the TRIM44-knockdown-induced decrease in LC3B expression and autophagosome formation as well as RABV replication. The results suggest that TRIM44 promotes RABV replication by an autophagy-dependent mechanism. Our work identifies TRIM44 as a key host factor for RABV replication, and targeting TRIM44 expression may represent an effective therapeutic strategy.

Oleocanthal Protects C2C12 Myotubes against the Pro-Catabolic and Anti-Myogenic Action of Stimuli Able to Induce Muscle Wasting In Vivo.

Oleocanthal (OC) is a monophenol of extra-virgin olive oil (EVOO) endowed with antibiotic, cardioprotective and anticancer effects, among others, mainly in view of its antioxidant and anti-inflammatory properties. OC has been largely investigated in terms of its anticancer activity, in Alzheimer disease and in collagen-induced arthritis; however, the possibility that it can also affect muscle biology has been totally overlooked so far. This study is the first to describe that OC modulates alterations induced in C2C12 myotubes by stimuli known to induce muscle wasting in vivo, namely TNF-α, or in the medium conditioned by the C26 cachexia-inducing tumor (CM-C26). C2C12 myotubes were exposed to CM-C26 or TNF-α in the presence or absence of OC for 24 and 48 h and analyzed by immunofluorescence and Western blotting. In combination with TNF-α or CM-C26, OC was revealed to be able to restore both the myotube's original size and morphology and normal levels of both atrogin-1 and MuRF1. OC seems unable to impinge on the autophagic-lysosomal proteolytic system or protein synthesis. Modulations towards normal levels of the expression of molecules involved in myogenesis, such as Pax7, myogenin and MyHC, were also observed in the myotube cultures exposed to OC and TNF-α or CM-C26. In conclusion, the data presented here show that OC exerts a protective action in C2C12 myotubes exposed to TNF-α or CM-C26, with mechanisms likely involving the downregulation of ubiquitin-proteasome-dependent proteolysis and the partial relief of myogenic differentiation impairment.

Protective role of pretreatment with Anisodamine against sepsis-induced diaphragm atrophy via inhibiting JAK2/STAT3 pathway.

There is an increasing tendency for sepsis patients to suffer from diaphragm atrophy as well as mortality. Therefore, reducing diaphragm atrophy could benefit sepsis patients' prognoses. Studies have shown that Anisodamine (Anis) can exert antioxidant effects when blows occur. However, the role of Anisodamine in diaphragm atrophy in sepsis patients has not been reported. Therefore, this study investigated the antioxidant effect of Anisodamine in sepsis-induced diaphragm atrophy and its mechanism. We used cecal ligation aspiration (CLP) to establish a mouse septic mode and stimulated the C2C12 myotube model with lipopolysaccharide (LPS). After treatment with Anisodamine, we measured the mice's bodyweight, diaphragm weight, fiber cross-sectional area and the diameter of C2C12 myotubes. The malondialdehyde (MDA) levels in the diaphragm were detected using the oxidative stress kit. The expression of MuRF1, Atrogin1 and JAK2/STAT3 signaling pathway components in the diaphragm and C2C12 myotubes was measured by RT-qPCR and Western blot. The mean fluorescence intensity of ROS in C2C12 myotubes was measured by flow cytometry. Meanwhile, we also measured the levels of Drp1 and Cytochrome C (Cyt-C) in vivo and in vitro by Western blot. Our study revealed that Anisodamine alleviated the reduction in diaphragmatic mass and the loss of diaphragmatic fiber cross-sectional area and attenuated the atrophy of the C2C12 myotubes by inhibiting the expression of E3 ubiquitin ligases. In addition, we observed that Anisodamine inhibited the JAK2/STAT3 signaling pathway and protects mitochondrial function. In conclusion, Anisodamine alleviates sepsis-induced diaphragm atrophy, and the mechanism may be related to inhibiting the JAK2/STAT3 signaling pathway.

NFKBIZ regulates NFκB signaling pathway to mediate tumorigenesis and metastasis of hepatocellular carcinoma by direct interaction with TRIM16.

Hepatocellular carcinoma (HCC) is a malignant tumor with high incidence and mortality rates. NFKBIZ, a member of the nuclear factor kappa B inhibitory family, is closely related to tumor progression. However, the precise role of NFKBIZ in HCC remains unclear. To explore this, we conducted a series of experiments from clinic to cells. Western blot and qPCR revealed a significant downregulation of NFKBIZ in human HCC tissues. Clinical character analysis showed that the patients with lower NFKBIZ expression had poorer prognosis and higher clinical stage. By using CCK-8, wound healing, transwell invasion and migration assay, we discovered that NFKBIZ expression was reversely associated with the proliferation, invasion, and migration ability of HCC cells in vitro. Additionally, the results obtained from xenograft assay and lung metastasis models showed that NFKBIZ overexpression inhibited the growth and metastasis of HCC cells in vivo. Western blot and immunofluorescence assay further revealed that NFKBIZ mediated HCC cell growth and migration by regulating NFκB signaling transduction. Finally, flow cytometry, protein degradation assay and Co-immunoprecipitation indicated that TRIM16 can enhance NFKBIZ ubiquitination by direct interactions at its K48 site, which may thereby alleviate HCC cell apoptosis to induce the insensitivity to sorafenib. In conclusion, our study demonstrated that NFKBIZ regulated HCC tumorigenesis and metastasis by mediating NFκB signal transduction and TRIM16/NFKBIZ/NFκB axis may be the underlying mechanism of sorafenib insensitivity in HCC.

Aminophylline Improves Ventilator-Induced Diaphragmatic Dysfunction by Targeting IGF-1-FOXO1-MURF1 Pathway.

BACKGROUND: The usage of life-saving mechanical ventilation (MV) could cause ventilator-induced diaphragmatic dysfunction (VIDD), increasing both mortality and morbidity. Aminophylline (AP) has the potential to enhance the contractility of animal skeletal muscle fibers and improve the activity of human respiratory muscles, and the insulin-like growth factor-1 (IGF-1)- forkhead box protein O1 (FOXO1)-muscle RING finger-1 (MURF1) pathway plays a crucial role in skeletal muscle dysfunction. This study aimed to investigate the impact of AP on VIDD and to elucidate the role of the IGF-1-FOXO1-MURF1 pathway as an underlying mechanism. METHODS: Rat models of VIDD were established through MV treatment. IGF-1 lentiviral (LV) interference (LV-IGF-1-shRNA; controlled by lentiviral negative control LV-NC) was employed to inhibit IGF-1 expression and thereby block the IGF-1-FOXO1-MURF1 pathway. Protein and mRNA levels of IGF-1, FOXO1, and MURF1 were assessed using western blot and real-time reverse transcriptase-polymerase chain reaction (RT-qPCR), respectively. Diaphragm contractility and morphometry were examined through measurement of compound muscle action potentials (CMAPs) and hematoxylin and eosin (H&E) staining. Oxidative stress was evaluated by levels of hydrogen peroxide (H2O2), superoxide dismutase (SOD), antioxidant glutathione (GSH), and carbonylated protein. Mitochondrial stability was assessed by measuring the mitochondrial membrane potential (MMP), and mitochondrial fission and mitophagy were examined through protein levels of dynamin-related protein 1 (DRP1), mitofusin 2 protein (MFN2), phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1), and Parkin (western blot). Apoptosis was evaluated using the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate (UTP) nick-end labeling (TUNEL) assay and levels of Bax, B-cell lymphoma 2 (BCL-2), and Caspase-3. Levels of Atrogin-1, neuronally expressed developmentally downregulated 4 (NEDD4), and muscle ubiquitin ligase of SCF complex in atrophy-1 (MUSA1) mRNA, as well as ubiquitinated protein, were utilized to determine protein degradation. Furthermore, the SUnSET (surface sensing of translation) method was employed to determine rates of protein synthesis. RESULTS: MV treatment upregulated IGF-1 while downregulated FOXO1 and MURF1 (p < 0.05). AP administration reversed IGF-1, FOXO1 and MURF1 (p < 0.05), which was suppressed again by IGF-1 inhibition (p < 0.05), demonstrating the blockage of the IGF-1-FOXO1-MURF1 pathway. MV treatment caused decreased CMAP and cross-sectional areas of diaphragm muscle fibers, and increased time course of CMAP (p < 0.05). Additionally, oxidative stress, cell apoptosis, and protein degradation were increased and mitochondrial stability was decreased by MV treatment (p < 0.05). Conversely, AP administration reversed all these changes induced by MV, but this reversal was disrupted by the blockage of the IGF-1-FOXO1-MURF1 pathway. CONCLUSIONS: In this study, MV treatment induced symptoms of VIDD in rats, which were all effectively reversed by AP regulating the IGF-1-FOXO1-MURF1 pathway, demonstrating the potential of AP in ameliorating VIDD.

The E3 ligase TRIM7 suppresses the tumorigenesis of gastric cancer by targeting SLC7A11.

Tripartite motif-containing protein 7 (TRIM7), as an E3 ligase, plays an important regulatory role in various physiological and pathological processes. However, the role of TRIM7 in gastric cancer (GC) is still undefined. Our study detected the expression of TRIM7 in clinical specimens and investigated the regulatory effect and molecular mechanism of TRIM7 on GC progression through in vitro and in vivo experiments. Our finding showed that TRIM7 was significantly downregulated in GC, and patients with high expression of TRIM7 showed long overall survival. Both in vitro and in vivo experiments showed that TRIM7 dramatically suppressed the malignant progression of GC. Further investigation showed that ferroptosis was the major death type mediated by TRIM7. Mechanistically, TRIM7 interacted with SLC7A11 through its B30.2/SPRY domain and promoted Lys48-linked polyubiquitination of SLC7A11, which effectively suppressing SLC7A11/GPX4 axis and inducing ferroptosis in GC cells. In vivo experiments and correlation analysis based on clinical specimens further confirmed that TRIM7 inhibited tumor growth through suppressing SLC7A11/GPX4 axis. In conclusion, our investigation demonstrated for the first time that TRIM7, as a tumor suppressor, induced ferroptosis via targeting SLC7A11 in GC, which provided a new strategy for the molecular therapy of GC by upregulating TRIM7.

TRIM6 facilitates SARS-CoV-2 proliferation by catalyzing the K29-typed ubiquitination of NP to enhance the ability to bind viral genomes.

The Nucleocapsid Protein (NP) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is not only the core structural protein required for viral packaging, but also participates in the regulation of viral replication, and its post-translational modifications such as phosphorylation have been shown to be an important strategy for regulating virus proliferation. Our previous work identified NP could be ubiquitinated, as confirmed by two independent studies. But the function of NP ubiquitination is currently unknown. In this study, we first pinpointed TRIM6 as the E3 ubiquitin ligase responsible for NP ubiquitination, binding to NP's CTD via its RING and B-box-CCD domains. TRIM6 promotes the K29-typed polyubiquitination of NP at K102, K347, and K361 residues, increasing its binding to viral genomic RNA. Consistently, functional experiments such as the use of the reverse genetic tool trVLP model and gene knockout of TRIM6 further confirmed that blocking the ubiquitination of NP by TRIM6 significantly inhibited the proliferation of SARS-CoV-2. Notably, the NP of coronavirus is relatively conserved, and the NP of SARS-CoV can also be ubiquitinated by TRIM6, indicating that NP could be a broad-spectrum anti-coronavirus target. These findings shed light on the intricate interaction between SARS-CoV-2 and the host, potentially opening new opportunities for COVID-19 therapeutic development.

TRIM5 as a promising diagnostic biomarker of hepatocellular carcinoma: integrated analysis and experimental validation.

The TRIM family is associated with the membrane, and its involvement in the progression, growth, and development of various cancer types has been researched extensively. However, the role played by the TRIM5 gene within this family has yet to be explored to a great extent in terms of hepatocellular carcinoma (HCC). The data of patients relating to mRNA expression and the survival rate of individuals diagnosed with HCC were extracted from The Cancer Genome Atlas (TCGA) database. UALCAN was employed to examine the potential link between TRIM5 expression and clinicopathological characteristics. In addition, enrichment analysis of differentially expressed genes (DEGs) was conducted as a means of deciphering the function and mechanism of TRIM5 in HCC. The data in the TCGA and TIMER2.0 databases was utilized to explore the correlation between TRIM5 and immune infiltration in HCC. WGCNA was performed as a means of assessing TRIM5-related co-expressed genes. The "OncoPredict" R package was also used for investigating the association between TRIM5 and drug sensitivity. Finally, qRT-PCR, Western blotting (WB) and immunohistochemistry (IHC) were employed for exploring the differential expression of TRIM5 and its clinical relevance in HCC. According to the results that were obtained from the vitro experiments, mRNA and protein levels of TRIM5 demonstrated a significant upregulation in HCC tissues. It is notable that TRIM5 expression levels were found to have a strong association with the infiltration of diverse immune cells and displayed a positive correlation with several immune checkpoint inhibitors. The TRIM5 expression also displayed promising clinical prognostic value for HCC patients.

Genetic loci regulate Sarbecovirus pathogenesis: A comparison across mice and humans.

Coronavirus (CoV) cause considerable morbidity and mortality in humans and other mammals, as evidenced by the emergence of Severe Acute Respiratory CoV (SARS-CoV) in 2003, Middle East Respiratory CoV (MERS-CoV) in 2012, and SARS-CoV-2 in 2019. Although poorly characterized, natural genetic variation in human and other mammals modulate virus pathogenesis, as reflected by the spectrum of clinical outcomes ranging from asymptomatic infections to lethal disease. Using multiple human epidemic and zoonotic Sarbecoviruses, coupled with murine Collaborative Cross genetic reference populations, we identify several dozen quantitative trait loci that regulate SARS-like group-2B CoV pathogenesis and replication. Under a Chr4 QTL, we deleted a candidate interferon stimulated gene, Trim14 which resulted in enhanced SARS-CoV titers and clinical disease, suggesting an antiviral role during infection. Importantly, about 60 % of the murine QTL encode susceptibility genes identified as priority candidates from human genome-wide association studies (GWAS) studies after SARS-CoV-2 infection, suggesting that similar selective forces have targeted analogous genes and pathways to regulate Sarbecovirus disease across diverse mammalian hosts. These studies provide an experimental platform in rodents to investigate the molecular-genetic mechanisms by which potential cross mammalian susceptibility loci and genes regulate type-specific and cross-SARS-like group 2B CoV replication, immunity, and pathogenesis in rodent models. Our study also provides a paradigm for identifying susceptibility loci for other highly heterogeneous and virulent viruses that sporadically emerge from zoonotic reservoirs to plague human and animal populations.

SP140 inhibitor suppressing TRIM22 expression regulates glioma progress through PI3K/AKT signaling pathway.

BACKGROUND: SP gene family, consisting of SP100, SP110, SP140, and SP140L, has been implicated in the initiation and advancement of numerous malignancies. Nevertheless, their clinical significance in glioma remains incompletely understood. METHOD: Expression levels and prognostic significance of SP family members were evaluated in the TCGA and CGGA datasets. Multifactorial analysis was used to identify SP gene family members that can independently impact the prognosis of glioma patients. A SP140-based predictive risk model/nomogram was developed in TCGA dataset and validated in CGGA dataset. The model's performance was evaluated through receiver operating characteristic (ROC) curves, calibration plots, and decision curve analyses. Phenotypic associations of SP140 and TRIM22 were examined through CancerSEA and TIMER. The effect of SP140 inhibitor in glioma progress and TRIM22/PI3K/AKT signaling pathway was confirmed in U251/U87 glioma cells. RESULTS: The SP family members exhibited elevated expression in gliomas and were negatively correlated with prognosis. SP140 emerged as an independent prognostic factor, and a SP140-based nomogram/predictive risk model demonstrated high accuracy. SP140 inhibitor, GSK761, lead to the suppression of TRIM22 expression and the PI3K/AKT signaling pathway. GSK761 also restrain glioma proliferation, migration, and invasion. Furthermore, SP140 and TRIM22 coexpressed in glioma cells with high level of vascular proliferation, TRIM22 is closely associated with the immune cell infiltration. CONCLUSION: SP140-based nomogram proved to be a practical tool for predicting the survival of glioma patients. SP140 inhibitor could suppress glioma progress via TRIM22/PI3K/AKT signaling pathway.

Integrated Multiomics Reveals Silencing of has_circ_0006646 Promotes TRIM21-Mediated NCL Ubiquitination to Inhibit Hepatocellular Carcinoma Metastasis.

Recent studies suggest that circular RNA (circRNA)-mediated post-translational modification of RNA-binding proteins (RBP) plays a pivotal role in metastasis of hepatocellular carcinoma (HCC). However, the specific mechanism and potential clinical therapeutic significance remain vague. This study attempts to profile the regulatory networks of circRNA and RBP using a multi-omics approach. Has_circ_0006646 (circ0006646) is an unreported circRNA in HCC and is associated with a poor prognosis. Silencing of circ0006646 significantly hinders metastasis in vivo. Mechanistically, circ0006646 prevents the interaction between nucleolin (NCL) and the E3 ligase tripartite motif-containing 21 to reduce the proteasome-mediated degradation of NCL via K48-linked polyubiquitylation. Furthermore, the change of NCL expression is proven to affect the phosphorylation levels of multiple proteins and inhibit p53 translation. Moreover, patient-derived tumor xenograft and lentivirus injection, which is conducted to simulate clinical treatment confirmed the potential therapeutic value. Overall, this study describes the integrated multi-omics landscape of circRNA-mediated NCL ubiquitination degradation in HCC metastasis and provides a novel therapeutic target.

TRIM65 promotes vascular smooth muscle cell phenotypic transformation by activating PI3K/Akt/mTOR signaling during atherogenesis.

BACKGROUND AND AIMS: Tripartite motif (TRIM65) is an important member of the TRIM protein family, which is a newly discovered E3 ligase that interacts with and ubiquitinates various substrates and is involved in diverse pathological processes. However, the function of TRIM65 in atherosclerosis remains unarticulated. In this study, we investigated the role of TRIM65 in the pathogenesis of atherosclerosis, specifically in vascular smooth muscle cells (VSMCs) phenotype transformation, which plays a crucial role in formation of atherosclerotic lesions. METHODS AND RESULTS: Both non-atherosclerotic and atherosclerotic lesions during autopsy were collected singly or pairwise from each individual (n = 16) to investigate the relationship between TRIM65 and the development of atherosclerosis. In vivo, Western diet-fed ApoE-/- mice overexpressing or lacking TRIM65 were used to assess the physiological function of TRIM65 on VSMCs phenotype, proliferation and atherosclerotic lesion formation. In vitro, VSMCs phenotypic transformation was induced by platelet-derived growth factor-BB (PDGF-BB). TRIM65-overexpressing or TRIM65-abrogated primary mouse aortic smooth muscle cells (MOASMCs) and human aortic smooth muscle cells (HASMCs) were used to investigate the mechanisms underlying the progression of VSMCs phenotypic transformation, proliferation and migration. Increased TRIM65 expression was detected in α-SMA-positive cells in the medial and atherosclerotic lesions of autopsy specimens. TRIM65 overexpression increased, whereas genetic knockdown of TRIM65 remarkably inhibited, atherosclerotic plaque development. Mechanistically, TRIM65 overexpression activated PI3K/Akt/mTOR signaling, resulting in the loss of the VSMCs contractile phenotype, including calponin, α-SMA, and SM22α, as well as cell proliferation and migration. However, opposite phenomena were observed when TRIM65 was deficient in vivo or in vitro. Moreover, in cultured PDGF-BB-induced TRIM65-overexpressing VSMCs, inhibition of PI3K by treatment with the inhibitor LY-294002 for 24 h markedly attenuated PI3K/Akt/mTOR activation, regained the VSMCs contractile phenotype, and blocked the progression of cell proliferation and migration. CONCLUSIONS: TRIM65 overexpression enhances atherosclerosis development by promoting phenotypic transformation of VSMCs from contractile to synthetic state through activation of the PI3K/Akt/mTOR signal pathway.

TRIM56: a promising prognostic immune biomarker for glioma revealed by pan-cancer and single-cell analysis.

Tripartite-motif 56 (TRIM56) is a member of the TRIM family, and was shown to be an interferon-inducible E3 ubiquitin ligase that can be overexpressed upon stimulation with double-stranded DNA to regulate stimulator of interferon genes (STING) to produce type I interferon and thus mediate innate immune responses. Its role in tumors remains unclear. In this study, we investigated the relationship between the expression of the TRIM56 gene and its prognostic value in pan-cancer, identifying TRIM56 expression as an adverse prognostic factor in glioma patients. Therefore, glioma was selected as the primary focus of our investigation. We explored the differential expression of TRIM56 in various glioma subtypes and verified its role as an independent prognostic factor in gliomas. Our research revealed that TRIM56 is associated with malignant biological behaviors in gliomas, such as proliferation, migration, and invasion. Additionally, it can mediate M2 polarization of macrophages in gliomas. The results were validated in vitro and in vivo. Furthermore, we utilized single-cell analysis to investigate the impact of TRIM56 expression on cell communication between glioma cells and non-tumor cells. We constructed a multi-gene signature based on cell markers of tumor cells with high TRIM56 expression to enhance the prediction of cancer patient prognosis. In conclusion, our study demonstrates that TRIM56 serves as a reliable immune-related prognostic biomarker in glioma.

Evaluation of TRIM63 RNA in situ hybridization (RNA-ISH) as a potential biomarker for alveolar soft-part sarcoma (ASPS).

Alveolar soft-part sarcoma (ASPS) is a rare soft tissue tumor with a broad morphologic differential diagnosis. While histology and immunohistochemistry can be suggestive, diagnosis often requires exclusion of other entities followed by confirmatory molecular analysis for its characteristic ASPSCR1-TFE3 fusion. Current stain-based biomarkers (such as immunohistochemistry for cathepsin K and TFE3) show relatively high sensitivity but may lack specificity, often showing staining in multiple other entities under diagnostic consideration. Given the discovery of RNA in situ hybridization (RNA-ISH) for TRIM63 as a sensitive and specific marker of MiTF-family aberration renal cell carcinomas, we sought to evaluate its utility in the workup of ASPS. TRIM63 RNA-ISH demonstrated high levels (H-score greater than 200) of expression in 19/20 (95%) cases of ASPS (average H-score 330) and was weak or negative in cases of paraganglioma, clear cell sarcoma, rhabdomyosarcoma, malignant epithelioid hemangioendothelioma, as well as hepatocellular and adrenal cortical carcinomas. Staining was also identified in tumors with known subsets characterized by TFE3 alterations such as perivascular epithelioid cell neoplasm (PEComa, average H-score 228), while tumors known to exhibit overexpression of TFE3 protein without cytogenetic alterations, such as melanoma and granular cell tumor, generally showed less TRIM63 ISH staining (average H-scores 147 and 96, respectively). Quantitative assessment of TRIM63 staining by RNA-ISH is potentially a helpful biomarker for tumors with molecular TFE3 alterations such as ASPS.

Genomic and transcriptome insight into the structure and immunity role of TRIM proteins in Chinese soft-shelled turtles (Pelodiscus sinensis) after Aeromonas hydrophila infection.

BACKGROUND: TRIM proteins, recognized as a class of E3 ubiquitin ligases, are increasingly acknowledged for their antipathogen immune functions in mammals and fish. In the Chinese soft-shelled turtle (Pelodiscus sinensis), a secondary aquatic reptile that occupies a unique evolutionary position, the TRIM gene has rarely been reported. METHODS AND RESULTS: In the present study, 48 PsTRIM proteins were identified from the genome of Pelodiscus sinensis via Hidden Markov Model (HMM) searches and Signal Transduction ATPases with Numerous Domains (SMART) analysis. These PsTRIMs were found across 43 distinct scaffolds, and phylogenetic analyses classified them into three principal clades. The PsTRIMs feature a conserved assembly of either RING-B-box-coiled-coil (RBCC) or B-box-coiled-coil (BBC) domains at the N-terminus, in addition to eight unique domains at the C-terminus, including the B30.2 domain, 19 of which were identified. Expression profiling revealed ubiquitous expression of the 48 PsTRIMs across various P. sinensis tissues. Notably, seven PsTRIMs exhibited significant differential expression in liver transcriptomes following infection with Aeromonas hydrophila. Weighted gene coexpression network analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis implicated PsTRIM14 and PsTRIM28 as key players in host defense against bacterial invasion. Real-time quantitative PCR results indicated that PsTRIM1, PsTRIM2, PsTRIM14, and PsTRIM28 experienced marked upregulation in P. sinensis livers at 12 h post-infection with A. hydrophila. CONCLUSIONS: Our study is the first to comprehensively identify and analyze the functions of TRIM genes in P. sinensis, unveiling their considerable diversity and potential roles in modulating immune responses.

TRIM72 restricts lyssavirus infection by inducing K48-linked ubiquitination and proteasome degradation of the matrix protein.

The tripartite motif (TRIM) protein family is the largest subfamily of E3 ubiquitin ligases, playing a crucial role in the antiviral process. In this study, we found that TRIM72, a member of the TRIM protein family, was increased in neuronal cells and mouse brains following rabies lyssavirus (RABV) infection. Over-expression of TRIM72 significantly reduced the viral titer of RABV in neuronal cells and mitigated the pathogenicity of RABV in mice. Furthermore, we found that TRIM72 over-expression effectively prevents the assembly and/or release of RABV. In terms of the mechanism, TRIM72 promotes the K48-linked ubiquitination of RABV Matrix protein (M), leading to the degradation of M through the proteasome pathway. TRIM72 directly interacts with M and the interaction sites were identified and confirmed through TRIM72-M interaction model construction and mutation analysis. Further investigation revealed that the degradation of M induced by TRIM72 was attributed to TRIM72's promotion of ubiquitination at site K195 in M. Importantly, the K195 site was found to be partially conserved among lyssavirus's M proteins, and TRIM72 over-expression induced the degradation of these lyssavirus M proteins. In summary, our study has uncovered a TRIM family protein, TRIM72, that can restrict lyssavirus replication by degrading M, and we have identified a novel ubiquitination site (K195) in lyssavirus M.

TRIM56-mediated production of type I interferon inhibits intracellular replication of Rickettsia rickettsii.

Rickettsia rickettsii (R. rickettsii), the causative agent of Rocky Mountain spotted fever (RMSF), is the most pathogenic member among Rickettsia spp. Previous studies have shown that tripartite motif-containing 56 (TRIM56) E3 ligase-induced ubiquitination of STING is important for cytosolic DNA sensing and type I interferon production to induce anti-DNA viral immunity, but whether it affects intracellular replication of R. rickettsii remains uncharacterized. Here, we investigated the effect of TRIM56 on HeLa and THP-1 cells infected with R. rickettsii. We found that the expression of TRIM56 was upregulated in the R. rickettsii-infected cells, and the overexpression of TRIM56 inhibited the intracellular replication of R. rickettsii, while R. rickettsii replication was enhanced in the TRIM56-silenced host cells with the reduced phosphorylation of IRF3 and STING and the increased production of interferon-ß. In addition, the mutation of the TRIM56 E3 ligase catalytic site impairs the inhibitory function against R. rickettsii in HeLa cells. Altogether, our study discovers that TRIM56 is a host restriction factor of R. rickettsii by regulating the cGAS-STING-mediated signaling pathway. This study gives new evidence for the role of TRIM56 in the innate immune response against intracellular bacterial infection and provides new therapeutic targets for RMSF. IMPORTANCE: Given that Rickettsia rickettsii (R. rickettsii) is the most pathogenic member within the Rickettsia genus and serves as the causative agent of Rocky Mountain spotted fever, there is a growing need to explore host targets. In this study, we examined the impact of host TRIM56 on R. rickettsii infection in HeLa and THP-1 cells. We observed a significant upregulation of TRIM56 expression in R. rickettsii-infected cells. Remarkably, the overexpression of TRIM56 inhibited the intracellular replication of R. rickettsii, while silencing TRIM56 enhanced bacterial replication accompanied by reduced phosphorylation of IRF3 and STING, along with increased interferon-ß production. Notably, the mutation of the TRIM56's E3 ligase catalytic site did not impede R. rickettsii replication in HeLa cells. Collectively, our findings provide novel insights into the role of TRIM56 as a host restriction factor against R. rickettsii through the modulation of the cGAS-STING signaling pathway.

HucMSCs Delay Muscle Atrophy After Peripheral Nerve Injury Through Exosomes by Repressing Muscle-Specific Ubiquitin Ligases.

Cell therapy based on mesenchymal stem cells (MSCs) alleviate muscle atrophy caused by diabetes and aging; however, the impact of human umbilical cord mesenchymal stem cells on muscle atrophy following nerve injury and the underlying mechanisms remain unclear. In this study, we evaluated the therapeutic efficacy of human umbilical cord MSCs (hucMSCs) and hucMSC-derived exosomes (hucMSC-EXOs) for muscle atrophy following nerve injury and identified the underlying molecular mechanisms. Sciatic nerve crush injury in rats and the induction of myotubes in L6 cells were used to determine the ameliorating effect of hucMSCs and hucMSC-EXOs on muscle atrophy. Q-PCR and Western blot analyses were used to measure the expression of muscle-specific ubiquitin ligases Fbxo32 (Atrogin1, MAFbx) and Trim63 (MuRF-1). Dual-luciferase reporter gene experiments were conducted to validate the direct binding of miRNAs to their target genes. Local injection of hucMSCs and hucMSC-EXOs mitigated atrophy in the rat gastrocnemius muscle following sciatic nerve crush injury. In vitro, hucMSC-EXOs alleviated atrophy in L6 myotubes. Mechanistic analysis indicated the upregulation of miR-23b-3p levels in L6 myotubes following hucMSC-EXOs treatment. MiR-23b-3p significantly inhibited the expression of its target genes, Fbxo32 and Trim63, and suppressed myotube atrophy. Notably, an miR-23b-3p inhibitor reversed the inhibitory effect of miR-23b-3p on myotube atrophy in vitro. These results suggest that hucMSCs and their exosomes alleviate muscle atrophy following nerve injury. MiR-23b-3p in exosomes secreted by hucMSCs contributes to this mechanism by inhibiting the muscle-specific ubiquitination ligases Fbxo32 and Trim63.

TRIM59 suppresses the brain ischaemia/reperfusion injury and pyroptosis of microglial through mediating the ubiquitination of NLRP3.

Cerebral ischaemia/reperfusion (I/R) injury induces irreversible brain injury and causes functional impairment. Ubiquitination plays a crucial role in protein degradation, but its role in cerebral I/R injury remains unclear. Differentially expressed genes in stroke were identified by analysing the microarray dataset GSE119121. Cerebral I/R was simulated in vitro by treating human microglial HMC3 cells with oxygen-glucose deprivation/reperfusion (OGD/R). Cell viability was tested by Cell Counting Kit 8 (CCK-8) assays, and pyroptosis was examined by flow cytometry. Lactate dehydrogenase (LDH) and inflammatory cytokine secretion were measured by LDH cytotoxicity assays and enzyme-linked immunosorbent assay (ELISA), respectively. The cerebral I/R animal model was established by middle cerebral artery occlusion (MCAO) surgery in rats. Bioinformatic analysis indicated that tripartite motif-containing protein 59 (TRIM59) is downregulated in stroke, which was verified in cerebral I/R models. The upregulation of TRIM59 promoted viability and inhibited pyroptosis in OGD/R-treated microglia and alleviated cerebral I/R injury in vivo. TRIM59 attenuated NOD-like receptor family pyrin domain containing 3 (NLRP3) protein expression through ubiquitination, thus degrading NLRP3 and alleviating OGD/R-induced injury. TRIM59 relieves cerebral I/R injury in vivo and in vivo. Mechanistically, TRIM59 directly interacts with NLRP3 and inhibits NLRP3 through ubiquitination. Targeting the TRIM59/NLRP3 signalling axis may be an effective therapeutic strategy for cerebral I/R.

The E3 ligase TRIM22 restricts SARS-CoV-2 replication by promoting proteasomal degradation of NSP8.

Replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome is mediated by a complex of non-structural proteins (NSPs), of which NSP7 and NSP8 serve as subunits and play a key role in promoting the activity of RNA-dependent RNA polymerase (RdRp) of NSP12. However, the stability of subunits of the RdRp complex has rarely been reported. Here, we found that NSP8 was degraded by the proteasome in host cells, and identified tripartite motif containing 22 (TRIM22) as its E3 ligase. The interferon (IFN) signaling pathway was activated upon viral invasion into host cells, and TRIM22 expression increased. TRIM22 interacted with NSP8 and ubiquitinated it at Lys97 via K48-type ubiquitination. TRIM22 overexpression significantly reduced viral RNA and protein levels. Knockdown of TRIM22 enhanced viral replication. This study provides a new explanation for treating patients suffering from SARS-CoV-2 with IFNs and new possibilities for drug development targeting the interaction between NSP8 and TRIM22.IMPORTANCENon-structural proteins (NSPs) play a crucial role in the replication of severe acute respiratory syndrome coronavirus 2, facilitating virus amplification and propagation. In this study, we conducted a comprehensive investigation into the stability of all subunits comprising the RNA-dependent RNA polymerase complex. Notably, our results reveal for the first time that NSP8 is a relatively unstable protein, which is found to be readily recognized and degraded by the proteasome. This degradation process is mediated by the host E3 ligase tripartite motif containing 22 (TRIM22), which is also a member of the interferon stimulated gene (ISG) family. Our study elucidates a novel mechanism of antiviral effect of TRIM22, which utilizes its own E3 ubiquitin ligase activity to hinder viral replication by inducing ubiquitination and subsequent degradation of NSP8. These findings provide new ideas for the development of novel therapeutic strategies. In addition, the conserved property of NSP8 raises the possibility of developing broad antiviral drugs targeting the TRIM22-NSP8 interaction.