TRIM16 controls assembly and degradation of protein aggregates by modulating the p62-NRF2 axis and autophagy

TRIM16 mitigates impaired osteogenic differentiation and antioxidant response in D-galactose-induced senescent osteoblasts

Senile osteoporosis (SOP), characterized by significant bone loss, poses a substantial threat to elderly skeletal health, with oxidative stress playing a crucial role in its pathogenesis. Although Tripartite Motif 16 (TRIM16) has been identified as a promoter of antioxidant response and osteogenic differentiation, its regulatory role in SOP remains incompletely understood. This study aims to elucidate the underlying mechanism of TRIM16 in mitigating D-galactose (D-gal)-induced senescent osteoblasts. Initially, we observed diminished bone mineral density (BMD) and impaired bone microstructure in naturally aging (24 months) and D-gal-induced (18 months) aged mice through Dual-energy X-ray absorptiometry (DEXA), micro-CT, hematoxylin and eosin staining, and Masson staining. Immunohistochemistry analysis revealed downregulation of TRIM16 and osteogenic differentiation markers (Collagen-1, Runx-2, osteopontin) in femur samples of aged mice. Furthermore, in D-gal-induced senescent MC3T3-E1 osteoblasts, we observed the suppression of osteogenic differentiation and maturity, along with cytoskeleton impairment via Alkaline phosphatase (ALP), Alizarin Red S, and Rhodamine-phalloidin staining. The protein expression of TRIM16, osteogenic differentiation markers, and antioxidant indicators (Nrf-2, HO-1, SOD1) decreased, while the production of reactive oxygen species (ROS) significantly increased. Knockdown and overexpression of TRIM16 using lentivirus in osteoblasts revealed that the downregulation of TRIM16 inhibited osteogenic differentiation and induced oxidative stress. Notably, TRIM16 overexpression partially attenuated D-gal-induced inhibition of osteogenic differentiation and increased oxidative stress. These findings suggest TRIM16 may mitigate impaired osteogenic differentiation and antioxidant response in D-gal-induced senescent osteoblasts, suggesting its potential as a therapeutic target for SOP.

The role of galectins in the regulation of autophagy and inflammasome in host immunity

Galectins, a family of glycan-binding proteins have been shown to bind a wide range of glycans. In the cytoplasm, these glycans can be endogenous (or "self"), originating from damaged endocytic vesicles, or exogenous (or "non-self"), found on the surface of invading microbial pathogens. Galectins can detect these unusual cytosolic exposures to glycans and serve as critical regulators in orchestrating immune responses in innate and adaptive immunity. This review provides an overview of how galectins modulate host cellular responses, such as autophagy, xenophagy, and inflammasome-dependent cell death program, to infection.

Selective depletion of HBV-infected hepatocytes by class A capsid assembly modulators requires high levels of intrahepatic HBV core protein

Capsid assembly mediated by hepatitis B virus (HBV) core protein (HBc) is an essential part of the HBV replication cycle, which is the target for different classes of capsid assembly modulators (CAMs). While both CAM-A ("aberrant") and CAM-E ("empty") disrupt nucleocapsid assembly and reduce extracellular HBV DNA, CAM-As can also reduce extracellular HBV surface antigen (HBsAg) by triggering apoptosis of HBV-infected cells in preclinical mouse models. However, there have not been substantial HBsAg declines in chronic hepatitis B (CHB) patients treated with CAM-As to date. To investigate this disconnect, we characterized the antiviral activity of tool CAM compounds in HBV-infected primary human hepatocytes (PHHs), as well as in HBV-infected human liver chimeric mice and mice transduced with adeno-associated virus-HBV. Mechanistic studies in HBV-infected PHH revealed that CAM-A, but not CAM-E, induced a dose-dependent aggregation of HBc in the nucleus which is negatively regulated by the ubiquitin-binding protein p62. We confirmed that CAM-A, but not CAM-E, induced HBc-positive cell death in both mouse models via induction of apoptotic and inflammatory pathways and demonstrated that the degree of HBV-positive cell loss was positively correlated with intrahepatic HBc levels. Importantly, we determined that there is a significantly lower level of HBc per hepatocyte in CHB patient liver biopsies than in either of the HBV mouse models. Taken together, these data confirm that CAM-As have a unique secondary mechanism with the potential to kill HBc-positive hepatocytes. However, this secondary mechanism appears to require higher intrahepatic HBc levels than is typically observed in CHB patients, thereby limiting the therapeutic potential.

Αnti-prion effects of anthocyanins

Prion diseases, also known as Transmissible Spongiform Encephalopathies (TSEs), are protein-based neurodegenerative disorders (NDs) affecting humans and animals. They are characterized by the conformational conversion of the normal cellular prion protein, PrPC, into the pathogenic isoform, PrPSc. Prion diseases are invariably fatal and despite ongoing research, no effective prophylactic or therapeutic avenues are currently available. Anthocyanins (ACNs) are unique flavonoid compounds and interest in their use as potential neuroprotective and/or therapeutic agents against NDs, has increased significantly in recent years. Therefore, we investigated the potential anti-oxidant and anti-prion effects of Oenin and Myrtillin, two of the most common anthocyanins, using the most accepted in the field overexpressing PrPScin vitro model and a cell free protein aggregation model. Our results, indicate both anthocyanins as strong anti-oxidant compounds, upregulating the expression of genes involved in the anti-oxidant response, and reducing the levels of Reactive Oxygen Species (ROS), produced due to pathogenic prion infection, through the activation of the Keap1-Nrf2 pathway. Importantly, they showcased remarkable anti-prion potential, as they not only caused the clearance of pathogenic PrPSc aggregates, but also completely inhibited the formation of PrPSc fibrils in the Cerebrospinal Fluid (CSF) of patients with Creutzfeldt-Jakob disease (CJD). Therefore, Oenin and Myrtillin possess pleiotropic effects, suggesting their potential use as promising preventive and/or therapeutic agents in prion diseases and possibly in the spectrum of neurodegenerative proteinopathies.

Unraveling the Role of the NLRP3 Inflammasome in Lymphoma: Implications in Pathogenesis and Therapeutic Strategies

Inflammasomes are multimeric protein complexes, sensors of intracellular danger signals, and crucial components of the innate immune system, with the NLRP3 inflammasome being the best characterized among them. The increasing scientific interest in the mechanisms interconnecting inflammation and tumorigenesis has led to the study of the NLRP3 inflammasome in the setting of various neoplasms. Despite a plethora of data regarding solid tumors, NLRP3 inflammasome's implication in the pathogenesis of hematological malignancies only recently gained attention. In this review, we investigate its role in normal lymphopoiesis and lymphomagenesis. Considering that lymphomas comprise a heterogeneous group of hematologic neoplasms, both tumor-promoting and tumor-suppressing properties were attributed to the NLRP3 inflammasome, affecting neoplastic cells and immune cells in the tumor microenvironment. NLRP3 inflammasome-related proteins were associated with disease characteristics, response to treatment, and prognosis. Few studies assess the efficacy of NLRP3 inflammasome therapeutic targeting with encouraging results, though most are still at the preclinical level. Further understanding of the mechanisms regulating NLRP3 inflammasome activation during lymphoma development and progression can contribute to the investigation of novel treatment approaches to cover unmet needs in lymphoma therapeutics.

Total saponins from Panax japonicus attenuate acute alcoholic liver oxidative stress and hepatosteatosis by p62-related Nrf2 pathway and AMPK-ACC/PPARα axis in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Panax japonicus (T. Nees) C.A. Mey. (PJ) has been used as a tonic traditional Chinese medicine (TCM) for years. Based on its meridian tropism in liver, spleen, and lung, PJ was popularly used to enhance the function of these organs. It is originally recorded with detoxicant effect on binge drink in Ben Cao Gang Mu Shi Yi, a persuasive Chinese materia medica. And binge dink has a close relationship with alcoholic liver disease (ALD). Hence, it's meaningful to investigate whether PJ exerts liver protection against binge drink toxicity.

AIM OF THE STUDY

This investigation was carried out not only to emphasize the right recognition of total saponins from PJ (SPJ), but also to study on its sober-up effectiveness and defensive mechanism against acute alcoholic liver injury in vivo and in vitro.

MATERIALS AND METHODS

SPJ constituents were verified by HPLC-UV analysis. In vivo, acute alcoholic liver oxidative stress and hepatosteatosis were established by continuous ethanol gavage to C57BL/6 mice for 3 days. SPJ was pre-administered for 7 days to investigate its protective efficacy. Loss of righting reflex (LORR) assay was employed to assess anti-inebriation effect of SPJ. Transaminases levels and hematoxylin and eosin (H&E) staining were measured to indicate the alcoholic liver injury. Antioxidant enzymes were measured to evaluate the oxidative stress degree in liver. Measurement of hepatic lipid accumulation was based on Oil Red O staining. Levels of inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA). In vitro, HepG2 cells were treated with ethanol for 24 h, and SPJ was pre-administered for 2 h. 2,7-dichlorofluorescein diacetate (DCFH-DA) was used as a probe to indicate reactive oxygen species (ROS) generation. Nrf2 activation was verified by the favor of specific inhibitor, ML385. The nuclear translocation of Nrf2 was indicated with immunofluorescence analysis. Proteins expressions of related pathways were determined by Western blotting.

RESULTS

Oleanane-type saponins are the most abundant constituents of SPJ. In this acute model, SPJ released inebriation of mice in a dose dependent manner. It decreased levels of serum ALT and AST, and hepatic TG. Besides, SPJ inhibited CYP2E1 expression and reduced MDA level in liver, with upregulations of antioxidant enzymes GSH, SOD and CAT. p62-related Nrf2 pathway was activated by SPJ with downstream upregulations of GCLC and NQO1 in liver. AMPK-ACC/PPARα axis was upregulated by SPJ to alleviate hepatic lipidosis. Hepatic IL-6 and TNF-α levels were downregulated by SPJ, which indicated a regressive lipid peroxidation in liver. In HepG2 cells, SPJ reduced ethanol-exposed ROS generation. Activated p62-related Nrf2 pathway was verified to contribute to the alleviation of alcohol-induced oxidative stress in hepatic cells.

CONCLUSION

This attenuation of hepatic oxidative stress and steatosis suggested the therapeutic value of SPJ for ALD.

ZnO nanoparticles impair autophagic flux and cell viability through the TRIM16-NRF2-p62 pathway in inflammatory keratinocytes

PURPOSE

Zinc oxide nanoparticles (ZnO NPs) are widely used in sunscreen, cosmetics, and topical drugs. Most previous studies have confirmed the safety of ZnO NPs applied to normal skin; however, little is known about the safety and potential toxicity of ZnO NPs applied to inflamed skin. This study aimed to evaluate the exposure risk of ZnO NPs in the treatment of inflammatory skin diseases.

METHODS

Normal human and tumor necrosis factor-α (TNF-α)-induced inflammatory keratinocytes were incubated with ZnO NPs to assess their toxic effects on cell viability and autophagy signaling pathway. Tandem mass tag (TMT)-based proteomics analysis was used to identify differentially expressed proteins following incubation of inflammatory keratinocytes with ZnO NPs. Protein expression was assessed by Western blot, and double fluorescent labeling and siRNA-knockdown further elucidated the role of the TRIM16-NRF2-p62 pathway in mediating the effects of ZnO NP.

RESULTS

In TNF-α-induced inflammatory keratinocytes, ZnO NPs activated cytoprotective autophagy and mediated p62-related autophagic flux block, thereby reducing the viability of inflammatory keratinocytes. Additionally, TRIM16-NRF2 was essential in ZnO NP-mediated autophagy flux block and cell viability reduction in inflammatory keratinocytes. Inhibition of the TRIM16-NRF2 pathway reduced p62 levels, alleviated autophagy flux blockade, and slightly restored the viability of inflammatory keratinocytes.

CONCLUSION

ZnO NPs activated protective cell autophagy. Blockade of autophagy flux mediated by the TRIM16-NRF2-p62 pathway led to decreased cell viability. This study provided a deeper understanding of the toxicity mechanism of ZnO NPs in inflammatory keratinocytes.

SQSTM1/p62 and Hepatic Mallory-Denk Body Formation in Alcohol-Associated Liver Disease

Sequestosome 1 (SQSTM1/p62; hereafter p62) is an autophagy receptor protein for selective autophagy primarily due to its direct interaction with the microtubule light chain 3 protein that specifically localizes on autophagosome membranes. As a result, impaired autophagy leads to the accumulation of p62. p62 is also a common component of many human liver disease-related cellular inclusion bodies, such as Mallory-Denk bodies, intracytoplasmic hyaline bodies, α1-antitrypsin aggregates, as well as p62 bodies and condensates. p62 also acts as an intracellular signaling hub, and it involves multiple signaling pathways, including nuclear factor erythroid 2-related factor 2, NF-κB, and the mechanistic target of rapamycin, which are critical for oxidative stress, inflammation, cell survival, metabolism, and liver tumorigenesis. This review discusses the recent insights of p62 in protein quality control, including the role of p62 in the formation and degradation of p62 stress granules and protein aggregates as well as regulation of multiple signaling pathways in the pathogenesis of alcohol-associated liver disease.

Saikosaponin A protects against uremic toxin indole‑3 acetic acid‑induced damage to the myocardium

Chronic kidney disease (CKD)‑associated cardiac injury is a common complication in patients with CKD. Indole‑3 acetic acid (IAA) is a uremic toxin that injures the cardiovascular system. Saikosaponin A (SSA) protects against pressure overload‑induced cardiac fibrosis. However, the role and molecular mechanisms of IAA and SSA in CKD‑associated cardiac injury remain unclear. The present study investigated the effects of IAA and SSA on CKD‑associated cardiac injury in neonatal mouse cardiomyocytes and a mouse model of CKD. The expression of tripartite motif‑containing protein 16 (Trim16), receptor interacting protein kinase 2 (RIP2) and phosphorylated‑p38 were assessed using western blotting. The ubiquitination of RIP2 was measured by coimmunoprecipitation, and mouse cardiac structure and function were evaluated using hematoxylin and eosin staining and echocardiography. The results demonstrated that, SSA inhibited IAA‑induced cardiomyocyte hypertrophy, upregulated Trim16 expression, downregulated RIP2 expression and decreased p38 phosphorylation. Furthermore, Trim16 mediated SSA‑induced degradation of RIP2 by ubiquitination. In a mouse model of IAA‑induced CKD‑associated cardiac injury, SSA upregulated the protein expression levels of Trim16 and downregulated those of RIP2. Moreover, SSA alleviated heart hypertrophy and diastolic dysfunction in IAA‑treated mice. Taken together, these results suggest that SSA is a protective agent against IAA‑induced CKD‑associated cardiac injury and that Trim16‑mediated ubiquitination‑related degradation of RIP2 and p38 phosphorylation may contribute to the development of CKD‑associated cardiac injury.

An update on the bridging factors connecting autophagy and Nrf2 antioxidant pathway

Macroautophagy/autophagy is a lysosome-dependent catabolic pathway for the degradation of intracellular proteins and organelles. Autophagy dysfunction is related to many diseases, including lysosomal storage diseases, cancer, neurodegenerative diseases, cardiomyopathy, and chronic metabolic diseases, in which increased reactive oxygen species (ROS) levels are also observed. ROS can randomly oxidize proteins, lipids, and DNA, causing oxidative stress and damage. Cells have developed various antioxidant pathways to reduce excessive ROS and maintain redox homeostasis. Treatment targeting only one aspect of diseases with autophagy dysfunction and oxidative stress shows very limited effects. Herein, identifying the bridging factors that can regulate both autophagy and antioxidant pathways is beneficial for dual-target therapies. This review intends to provide insights into the current identified bridging factors that connect autophagy and Nrf2 antioxidant pathway, as well as their tight interconnection with each other. These factors could be potential dual-purpose targets for the treatment of diseases implicated in both autophagy dysfunction and oxidative stress.

Stress granule homeostasis is modulated by TRIM21-mediated ubiquitination of G3BP1 and autophagy-dependent elimination of stress granules

Eukaryotic stress granules (SGs) are highly dynamic assemblies of untranslated mRNAs and proteins that form through liquid-liquid phase separation (LLPS) under cellular stress. SG formation and elimination process is a conserved cellular strategy to promote cell survival, although the precise regulation of this process is poorly understood. Here, we screened six E3 ubiquitin ligases present in SGs and identified TRIM21 (tripartite motif containing 21) as a central regulator of SG homeostasis that is highly enriched in SGs of cells under arsenite-induced oxidative stress. Knockdown of TRIM21 promotes SG formation whereas overexpression of TRIM21 inhibits the formation of physiological and pathological SGs associated with neurodegenerative diseases. TRIM21 catalyzes K63-linked ubiquitination of the SG core protein, G3BP1 (G3BP stress granule assembly factor 1), and G3BP1 ubiquitination can effectively inhibit LLPS, in vitro. Recent reports suggested the involvement of macroautophagy/autophagy, as a stress response pathway, in the regulation of SG homeostasis. We systematically investigated well-defined autophagy receptors and identified SQSTM1/p62 (sequestosome 1) and CALCOCO2/NDP52 (calcium binding and coiled-coil domain 2) as the primary receptors that directly interact with G3BP1 during arsenite-induced stress. Endogenous SQSTM1 and CALCOCO2 localize to the periphery of SGs under oxidative stress and mediate SG elimination, as single knockout of each receptor causes accumulation of physiological and pathological SGs. Collectively, our study broadens the understanding in the regulation of SG homeostasis by showing that TRIM21 and autophagy receptors modulate SG formation and elimination respectively, suggesting the possibility of clinical targeting of these molecules in therapeutic strategies for neurodegenerative diseases.Abbreviations: ACTB: actin beta; ALS: amyotrophic lateral sclerosis; BafA1: bafilomycin A1; BECN1: beclin 1; C9orf72: C9orf72-SMCR8 complex subunit; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; Co-IP: co-immunoprecipitation; DAPI: 4',6-diamidino-2-phenylindole; FTD: frontotemporal dementia; FUS: FUS RNA binding protein; G3BP1: G3BP stress granule assembly factor 1; GFP: green fluorescent protein; LLPS: liquid-liquid phase separation; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NBR1: NBR1 autophagy cargo receptor; NES: nuclear export signal; OPTN: optineurin; RFP: red fluorescent protein; SQSTM1/p62: sequestosome 1; SG: stress granule; TAX1BP1: Tax1 binding protein 1; TOLLIP: toll interacting protein; TRIM21: tripartite motif containing 21; TRIM56: tripartite motif containing 56; UB: ubiquitin; ULK1: unc-51 like autophagy activating kinase 1; WT: wild-type.

TRIM16 Overexpression in HEK293T Cells Results in Cell Line-Specific Antiviral Activity

Host cell restriction factors are intracellular proteins that can inhibit virus replication. Characterisation of novel host cell restriction factors can provide potential targets for host-directed therapies. In this study, we aimed to assess a member of the Tripartite-motif family protein (TRIM) family, TRIM16, as a putative host cell restriction factor. To this end, we utilized constitutive or doxycycline-inducible systems to overexpress TRIM16 in HEK293T epithelial cells and then tested for its ability to inhibit growth by a range of RNA and DNA viruses. In HEK293T cells, overexpression of TRIM16 resulted in potent inhibition of multiple viruses, however, when TRIM16 was overexpressed in other epithelial cell lines (A549, Hela, or Hep2), virus inhibition was not observed. When investigating the antiviral activity of endogenous TRIM16, we report that siRNA-mediated knockdown of TRIM16 in A549 cells also modulated the mRNA expression of other TRIM proteins, complicating the interpretation of results using this method. Therefore, we used CRISPR/Cas9 editing to knockout TRIM16 in A549 cells and demonstrate that endogenous TRIM16 did not mediate antiviral activity against the viruses tested. Thus, while initial overexpression in HEK293T cells suggested that TRIM16 was a host cell restriction factor, alternative approaches did not validate these findings. These studies highlight the importance of multiple complementary experimental approaches, including overexpression analysis in multiple cell lines and investigation of the endogenous protein, when defining host cell restriction factors with novel antiviral activity.

SMURF1 attenuates endoplasmic reticulum stress by promoting the degradation of KEAP1 to activate NRF2 antioxidant pathway

Cancer cells consistently utilize the unfolded protein response (UPR) to encounter the abnormal endoplasmic reticulum (ER) stress induced by the accumulation of misfolded proteins. Extreme activation of the UPR could also provoke maladaptive cell death. Previous reports have shown that NRF2 antioxidant signaling is activated by UPR and serves as noncanonical pathway to defense and reduce excessive ROS levels during ER stress. However, the mechanisms of regulating NRF2 signaling upon ER stress in glioblastoma have not been fully elucidated. Here we identify that SMURF1 protects against ER stress and facilitates glioblastoma cell survival by rewiring KEAP1-NRF2 pathway. We show that ER stress induces SMURF1 degradation. Knockdown of SMURF1 upregulates IRE1 and PERK signaling in the UPR pathway and prevents ER-associated protein degradation (ERAD) activity, leading to cell apoptosis. Importantly, SMURF1 overexpression activates NRF2 signaling to reduce ROS levels and alleviate UPR-mediated cell death. Mechanistically, SMURF1 interacts with and ubiquitinates KEAP1 for its degradation (NRF2 negative regulator), resulting in NRF2 nuclear import. Moreover, SMURF1 loss reduces glioblastoma cell proliferation and growth in subcutaneously implanted nude mice xenografts. Taken together, SMURF1 rewires KEAP1-NRF2 pathway to confer resistance to ER stress inducers and protect glioblastoma cell survival. ER stress and SMURF1 modulation may provide promising therapeutic targets for the treatment of glioblastoma.

The interrelation of galectins and autophagy

Autophagy is a vital physiological process that maintains intracellular homeostasis by removing damaged organelles and senescent or misfolded molecules. However, excessive autophagy results in cell death and apoptosis, which will lead to a variety of diseases. Galectins are a type of animal lectin that binds to β-galactosides and can bind to the cell surface or extracellular matrix glycans, affecting a variety of immune processes in vivo and being linked to the development of many diseases. In many cases, galectins and autophagy both play important regulatory roles in the cellular life course, yet our understanding of the relationship between them is still incomplete. Galectins and autophagy may share common etiological cofactors for some diseases. Hence, we summarize the relationship between galectins and autophagy, aiming to draw attention to the existence of multiple associations between galectins and autophagy in a variety of physiological and pathological processes, which provide new ideas for etiological diagnosis, drug development, and therapeutic targets for related diseases.

Weighted gene co-expression network analysis identifies the prognosis-related models of left- and right-sided colon cancer

Left-sided colon cancer (LC) and right-sided colon cancer (RC) are 2 essentially different diseases, and the potential mechanisms regulating them remain unidentified. In this study, we applied weighted gene co-expression network analysis (WGCNA) to confirm a yellow module, mainly enriched in metabolism-related signaling pathways related to LC and RC. Based on the RNA-seq data of colon cancer in The Cancer Genome Atlas (TCGA) and GSE41258 dataset with their corresponding clinical information, a training set (TCGA: LC: n = 171; RC: n = 260) and a validation set (GSE41258: LC: n = 94; RC: n = 77) were divided. Least absolute shrinkage and selection operator (LASSO) penalized COX regression analysis identified 20 prognosis-related genes (PRGs) and helped constructed 2 risk (LC-R and RC-R) models in LC and RC, respectively. The model-based risk scores accurately performed in risk stratification for colon cancer patients. The high-risk group of the LC-R model showed associations with ECM-receptor interaction, focal adhesion, and PI3K-AKT signaling pathway. Interestingly, the low-risk group of the LC-R model showed associations with immune-related signaling pathways like antigen processing and presentation. On the other hand, the high-risk group of the RC-R model showed enrichment for cell adhesion molecules and axon guidance signaling pathways. Furthermore, we identified 20 differentially expressed PRGs between LC and RC. Our findings provide new insights into the difference between LC and RC, and uncover the potential biomarkers for the treatment of LC and RC.

An update on the role of TRIM/NLRP3 signaling pathway in atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease of large and medium arteries that includes lipid metabolism disorder and recruitment of immune cells to the artery wall. An increasing number of studies have confirmed that inflammasome over-activation is associated with the onset and progression of atherosclerosis. The NLRP3 inflammasome, in particular, has been proven to increase the incidence rate of cardiovascular diseases (CVD) by promoting pro-inflammatory cytokine release and reducing plaque stability. The strict control of inflammasome and prevention of excessive inflammatory reactions have been the research focus of inflammatory diseases. Tripartite motif (TRIM) is a protein family with a conservative structure and rapid evolution. Several studies have demonstrated the TRIM family's regulatory role in mediating inflammation. This review aims to clarify the relationship between TRIMs and NLRP3 inflammasome and provide insights for future research and treatment discovery.

Git1-PGK1 interaction achieves self-protection against spinal cord ischemia-reperfusion injury by modulating Keap1/Nrf2 signaling

Spinal cord ischemia-reperfusion (IR) injury (SCIRI) is a significant secondary injury that causes damage to spinal cord neurons, leading to the impairment of spinal cord sensory and motor functions. Excessive reactive oxygen species (ROS) production is considered one critical mechanism of neuron damage in SCIRI. Nonetheless, the molecular mechanisms underlying the resistance of neurons to ROS remain elusive. Our study revealed that the deletion of Git1 in mice led to poor recovery of spinal cord motor function after SCIRI. Furthermore, we discovered that Git1 has a beneficial effect on neuron resistance to ROS production. Mechanistically, Git1 interacted with PGK1, regulated PGK1 phosphorylation at S203, and affected the intermediate products of glycolysis in neurons. The influence of Git1 on glycolysis regulates the dimerization of Keap1, which leads to changes in Nrf2 ubiquitination and plays a role in resisting ROS. Collectively, we show that Git1 regulates the Keap1/Nrf2 axis to resist ROS in a PGK1-dependent manner and thus is a potential therapeutic target for SCIRI.

Enhanced liquidity of p62 droplets mediated by Smurf1 links Nrf2 activation and autophagy

BACKGROUND

Macro-autophagy/Autophagy is an evolutionarily well-conserved recycling process to maintain the balance through precise spatiotemporal regulation. However, the regulatory mechanisms of biomolecular condensates by the key adaptor protein p62 via liquid-liquid phase separation (LLPS) remain obscure.

RESULTS

In this study, we showed that E3 ligase Smurf1 enhanced Nrf2 activation and promoted autophagy by increasing p62 phase separation capability. Specifically, the Smurf1/p62 interaction improved the formation and material exchange of liquid droplets compared with p62 single puncta. Additionally, Smurf1 promoted the competitive binding of p62 with Keap1 to increase Nrf2 nuclear translocation in p62 Ser349 phosphorylation-dependent manner. Mechanistically, overexpressed Smurf1 increased the activation of mTORC1 (mechanistic target of rapamycin complex 1), in turn leading to p62 Ser349 phosphorylation. Nrf2 activation increased the mRNA levels of Smurf1, p62, and NBR1, further promoting the droplet liquidity to enhance oxidative stress response. Importantly, we showed that Smurf1 maintained cellular homeostasis by promoting cargo degradation through the p62/LC3 autophagic pathway.

CONCLUSIONS

These findings revealed the complex interconnected role among Smurf1, p62/Nrf2/NBR1, and p62/LC3 axis in determining Nrf2 activation and subsequent clearance of condensates through LLPS mechanism.

Effects of short-term high-concentration exposure to PM2.5 on pulmonary tissue damage and repair ability as well as innate immune events

Short-term heavy air pollution still occurs frequently worldwide, especially during the winter heating period in some developing countries, which is usually accompanied by the temporary explosive growth of PM_2.5. The pulmonary damage caused by PM_2.5 exposure has been determined, but there have been few studies on the repair ability after the cessation of exposure and the important role of innate immune events. This study established a short-term (30 days) high-concentration (15 mg/kg body weight) PM_2.5 exposure and recovery (15 days of exposure cessation) model by intratracheal instillation. The results showed that short-term PM_2.5 exposure increased the content of collagen fiber in rat lung tissue, which was significantly repaired after recovery by 15 days of exposure cessation. Meanwhile, exposure to PM_2.5 also caused changes in lung epithelial function, macrophage polarization and cell autophagy function. Most of these changes could be restored or reversed to a certain extent after recovery. However, there were also some biomarkers, including CLDN18.1, SP-A, SP-D, iNOS, CD206, Beclin1, p62 and LC3B, that were still significantly different between the exposure and control groups after recovery, suggesting that some toxic effects, especially epithelial function damage, were not completely repaired. In addition, there was a significant correlation between pulmonary fibrosis and innate immunity. The present study demonstrated that short-term high-concentration exposure to PM_2.5 could cause temporary lung tissue damage and related innate immune events in rats, and the repair ability existed after the cessation of exposure, but part of the damage that required special attention still persisted.

Ciliatoside A, isolated from Peristrophe japonica, inhibits HBsAg expression and cccDNA transcription by inducing autophagy

Hepatitis B surface antigen (HBsAg) loss and seroconversion are considered as an end point of a functional cure. Therefore, it is crucial to find new agents which could efficiently decrease HBsAg. Traditional herbal plants have been considered as an important source of new hepatitis B drugs development for their extensive use in antimicrobial and anti-inflammation. In this study, Peristrophe japonica, which could remarkably reduce HBsAg in the supernatant of HepG2.2.15 cells, was screened out for further extraction. Here, an active ethyl acetate fraction of Peristrophe japonica containing 34 sub-fractions was extracted. Subsequently, the monomeric compound Ciliatoside A was isolated and identified as a potential antiviral reagent with low cytotoxicity from Fraction 30. Ciliatoside A exhibited strong inhibition on intracellular and circulating HBsAg and HBV RNAs in HBV-infected cells and an HBV recombinant-cccDNA mouse model. The mechanistic study revealed that Ciliatoside A exhibited a potent anti-HBV effect through inducing autophagy-lysosomal pathway to autophagic degradation of HBc by activating AMPK-ULK1 axis and inhibiting mTOR activation. In summary, we have identified a novel antiviral compound Ciliatoside A isolated from Peristrophe japonica. This study may provide important direction and new ideas for the discovery of hepatitis B cure drugs.

Mechanism of autophagy induced by activation of the AMPK/ERK/mTOR signaling pathway after TRIM22-mediated DENV-2 infection of HUVECs

BACKGROUND

Dengue virus type 2 (DENV-2) was used to infect primary human umbilical vein endothelial cells (HUVECs) to examine autophagy induced by activation of the adenosine monophosphate-activated protein kinase (AMPK)/extracellular signal-regulated kinase (ERK)/mammalian target of rapamycin (mTOR) signaling pathway following tripartite motif-containing 22 (TRIM22)-mediated DENV-2 infection to further reveal the underlying pathogenic mechanism of DENV-2 infection.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to screen putative interference targets of TRIM22 and determine the knockdown efficiency. The effect of TRIM22 knockdown on HUVEC proliferation was determined using the CCK8 assay. Following TRIM22 knockdown, transmission electron microscopy (TEM) was used to determine the ultrastructure of HUVEC autophagosomes and expression of HUVEC autophagy and AMPK pathway-related genes were measured by qRT-PCR. Moreover, HUVEC autophagy and AMPK pathway-related protein expression levels were determined by western blot analysis. Cell cycle and apoptosis were assessed by flow cytometry (FCM) and the autophagosome structure of the HUVECs was observed by TEM.

RESULTS

Western blot results indicated that TRIM22 protein expression levels increased significantly 36 h after DENV-2 infection, which was consistent with the proteomics prediction. The CCK8 assay revealed that HUVEC proliferation was reduced following TRIM22 knockdown (P < 0.001). The TEM results indicated that HUVEC autolysosomes increased and autophagy was inhibited after TRIM22 knockdown. The qRT-PCR results revealed that after TRIM22 knockdown, the expression levels of antithymocyte globulin 7 (ATG7), antithymocyte globulin 5 (ATG5), Beclin1, ERK, and mTOR genes decreased (P < 0.01); however, the expression of AMPK genes (P < 0.05) and P62 genes (P < 0.001) increased. FCM revealed that following TRIM22 knockdown, the percentage of HUVECs in the G2 phase increased (P < 0.001) along with cell apoptosis. The effect of TRIM22 overexpression on HUVEC autophagy induced by DENV-2 infection and AMPK pathways decreased after adding an autophagy inhibitor.

CONCLUSIONS

In HUVECs, TRIM22 protein positively regulates autophagy and may affect autophagy through the AMPK/ERK/mTOR signaling pathway. Autophagy is induced by activation of the AMPK/ERK/mTOR signaling pathway following TRIM22-mediated DENV-2 infection of HUVECs.

Autophagy inhibition and reactive oxygen species elimination by acetyl-CoA acetyltransferase 1 through fused in sarcoma protein to promote prostate cancer

BACKGROUND

Prostate cancer is a major health issue affecting the male population worldwide, and its etiology remains relatively unknown. As presented on the Gene Expression Profiling Interactive Analysis database, acetyl-CoA acetyltransferase 1 (ACAT1) acts as a prostate cancer-promoting factor. ACAT1 expression in prostate cancer tissues is considerably higher than that in normal tissues, leading to a poor prognosis in patients with prostate cancer. Here, we aimed to study the role of the ACAT1-fused in sarcoma (FUS) complex in prostate cancer and identify new targets for the diagnosis and treatment of the disease.

METHODS

We conducted immunohistochemical analysis of 57 clinical samples and in vitro and in vivo experiments using a mouse model and plasmid constructs to determine the expression of ACAT1 in prostate cancer.

RESULTS

The relationship between the expression of ACAT1 and the Gleason score was significant. The expression of ACAT1 was higher in tissues with a Gleason score of > 7 than in tissues with a Gleason score of ≤7 (P = 0.0011). In addition, we revealed that ACAT1 can interact with the FUS protein.

CONCLUSIONS

In prostate cancer, ACAT1 promotes the expression of P62 and Nrf2 through FUS and affects reactive oxygen species scavenging. These effects are due to the inhibition of autophagy by ACAT1. That is, ACAT1 promotes prostate cancer by inhibiting autophagy and eliminating active oxygen species. The expression of ACAT1 is related to prostate cancer. Studying the underlying mechanism may provide a new perspective on the treatment of prostate cancer.

Genome-wide identification of antisense lncRNAs and their association with susceptibility to Flavobacterium psychrophilum in rainbow trout

Eukaryotic genomes encode long noncoding natural antisense transcripts (lncNATs) that have been increasingly recognized as regulatory members of gene expression. Recently, we identified a few antisense transcripts correlating in expression with immune-related genes. However, a systematic genome-wide analysis of lncNATs in rainbow trout is lacking. This study used 134 RNA-Seq datasets from five different projects to identify antisense transcripts. A total of 13,503 lncNATs were identified genome-wide. About 75% of lncNATs showed multiple exons compared to 36.5% of the intergenic lncRNAs. RNA-Seq datasets from resistant, control, and susceptible rainbow trout genetic lines with significant differences in survival rate following Flavobacterium psychrophilum (Fp) infection were analyzed to investigate the potential role of the lncNATs during infection. Twenty-four pairwise comparisons between the different genetic lines, infectious status, and time points revealed 581 differentially expressed (DE) lncNATs and 179 differentially used exons (DUEs). Most of the DE lncNATs strongly and positively correlated in expression with their corresponding sense transcripts across 24 RNA-Seq datasets. LncNATs complementary to genes related to immunity, muscle contraction, proteolysis, and iron/heme metabolism were DE following infection. LncNATs complementary to hemolysis-related genes were DE in the resistant fish compared to susceptible fish on day 5 post-infection, suggesting enhanced clearance of free hemoglobin (Hb) and heme and increased erythropoiesis. LncNATs complementary to hepcidin, a master negative regulator of the plasma iron concentration, were the most downregulated lncNATs on day 5 of bacterial infection in the resistant fish. Ninety-four DE lncNAT, including five complementary to hepcidin, are located within 26 QTL regions previously identified in association with bacterial cold water disease (BCWD) in rainbow trout. Collectively, lncNATs are involved in the molecular architecture of fish immunity and should be further investigated for potential applications in genomic selection and genetic manipulation in aquaculture.

TRIM16 promotes aerobic glycolysis and pancreatic cancer metastasis by modulating the NIK-SIX1 axis in a ligase-independent manner

Enhanced aerobic glycolysis contributes to the metastasis of pancreatic cancer metastasis, but the mechanism underlying the abnormal activation of glycolysis has not been fully elucidated. The E3 ligase tripartite motif 16 (TRIM16) is involved in the progression of many cancers. However, the role of and molecular mechanism by which TRIM16 acts in pancreatic cancer are unclear. In this study, we report that TRIM16 was significantly upregulated in pancreatic cancer tissues, and high expression of TRIM16 was associated with poor prognosis in patients with pancreatic cancer. Multivariate analyses showed that TRIM16 was an independent predictor of poor outcomes among patients with pancreatic cancer. In addition, in vitro and in vivo evidence showed that TRIM16 promoted pancreatic cancer cell metastasis by enhancing glycolysis. Furthermore, we revealed that TRIM16 controlled glycolysis and pancreatic cancer cell's metastasis by regulating sine oculis homeobox 1 (SIX1), an important transcription factor that promotes glycolysis. TRIM16 upregulated SIX1 by inhibiting its ubiquitination and degradation, which was mediated by NF-κB-inducing kinase (NIK), an upstream regulator of SIX1. Hence, NIK inhibitor can suppress SIX1 expression, glycolysis and metastasis in TRIM16-overexpressing pancreatic cancer cells. Mechanistic investigations demonstrated that TRIM16 competed with NIK's E3 ligase, TNF receptor-associated factor 3 (TRAF3), at the ISIIAQA sequence motif of NIK, and then stabilized NIK protein. Our study identified the TRIM16-NIK-SIX1 axis as a critical regulatory pathway in aerobic glycolysis and pancreatic cancer metastasis, indicating that this axis can be an excellent therapeutic target for curing pancreatic cancer.

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.

TRIM3 and TRIM16 as potential tumor suppressors in breast cancer patients

Objective

Breast cancer is the leading cause of death among women in many countries. Numerous factors serve as oncogenes or tumor suppressors in breast cancer. The large family of Tripartite-motif (TRIM) proteins with ~ 80 members has drawn attention for their role in cancer. TRIM3 and TRIM16 have shown suppressive activity in different cancers. This study aimed to evaluate the expression of TRIM3 and TRIM16 in cancerous and normal breast samples and to investigate their association with different clinical and pathological parameters.

Results

qRT-PCR was utilized to determine the gene expression of TRIM3 and TRIM16. The expression of TRIM3 and TRIM16 genes in tumor samples were significantly reduced to 0.45 and 0.29 fold, respectively. TRIM3 and TRIM16 genes expression were both positively correlated with the invasion of breast cancer. TRIM3 gene expression was associated with tumors’ histological grade. However, no significant association was found between the expression of the genes and tumor size, stage and necrosis. The expression of TRIM3 and TRIM16 are significantly reduced in breast cancer tissues. Besides, the expression of both TRIM3 and TRIM16 genes significantly plummet in lymphatic/vascular and perineural invasive samples. Hence, we suggest a potential tumor suppressor role for TRIM3 and TRIM16 in breast cancer.

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.

Ammonium tetrathiomolybdate triggers autophagy-dependent NRF2 activation in vascular endothelial cells

Ammonium tetrathiomolybdate (TTM) is a copper chelator in clinical trials for treatment of Wilson's disease, tumors and other diseases. In the current study, we innovatively discovered that TTM is a novel NRF2 activator and illustrated that autophagy contributed to TTM-induced NRF2 activation. We showed that TTM treatment promoted NRF2 nuclear translocation and upregulated transcription level of NRF2 target genes including HMOX1, GCLM, and SLC7A11 in vascular endothelial cells (HUVECs). Moreover, NRF2 deficiency directly hindered TTM-mediated antioxidative effects. Followingly, we revealed that overexpression of KEAP1, a negative regulator of NRF2, significantly repressed NRF2 activation induced by TTM. Further mutation analysis revealed that KEAP1 Cys151 is a major sensor responsible for TTM-initiated NRF2 signaling, suggesting that KEAP1 is involved in TTM-mediated NRF2 activation. Notably, we found that TTM can trigger autophagy as evidenced by accumulation of autophagosomes, elevation of LC3BI-II/I, increase of LC3 puncta and activation of AMPK/mTOR/ULK1 pathway. Autophagic flux assay indicated that TTM significantly enhanced autophagic flux in HUVECs. Inhibition of autophagy with knockout of autophagy key gene ATG5 resulted in suppression of TTM-induced NRF2 activation. TTM also induced phosphorylation of autophagy receptor SQSTM1 at Ser349, while SQSTM1-deficiency inhibited KEAP1 degradation and blocked NRF2 signaling pathway, suggesting that TTM-induced NRF2 activation is autophagy dependent. As the novel NRF2 activator, TTM protected against sodium arsenite (NaAsO₂)-induced oxidative stress and cell death, while NRF2 deficiency weakened TTM antioxidative effects. Finally, we showed that autophagy-dependent NRF2 activation contributed to the protective effects of TTM against NaAsO₂-induced oxidative injury, because of ATG5 or SQSTM1 knockout aggravated NaAsO₂-induced elevation of HMOX1, cleaved PARP and γH2AX. Taken together, our findings highlight copper chelator TTM is a novel autophagy-dependent NRF2 activator and shed a new light on the cure for oxidative damage-related 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.

tert-Butylhydroquinone-induced formation of high-molecular-weight p62: A novel mechanism in the activation of Nrf2-Keap1

The respiratory system is always exposed to air and is most vulnerable to attack by environmental free radicals. The nuclear factor E2-related factor 2-Kelch-like ECH-associated protein 1-antioxidant response element (Nrf2-Keap1-ARE) pathway and p62 are both involved in the oxidative stress response. However, the interplay between these two systems remains largely unknown. This study shows that treatment of L2 cells with tert-Butylhydroquinone (tBHQ) generates a high-molecular-weight (HMW) form of p62, leading to activation of the Nrf2-Keap1-ARE pathway. The levels of HMW-p62 increased as the tBHQ concentration increased, with concomitant decreases seen in the classical form of p62. Moreover, small interfering RNA targeting p62 increases Keap1 protein levels and inactivates the Nrf2-Keap1-ARE pathway. These results demonstrate that the Nrf2-Keap1 pathway is partially regulated by p62. tBHQ-induced HMW-p62 production may be a novel mechanism in the activation of the Nrf2-Keap1-ARE pathway.

A guide to membrane atg8ylation and autophagy with reflections on immunity

The process of membrane atg8ylation, defined herein as the conjugation of the ATG8 family of ubiquitin-like proteins to membrane lipids, is beginning to be appreciated in its broader manifestations, mechanisms, and functions. Classically, membrane atg8ylation with LC3B, one of six mammalian ATG8 family proteins, has been viewed as the hallmark of canonical autophagy, entailing the formation of characteristic double membranes in the cytoplasm. However, ATG8s are now well described as being conjugated to single membranes and, most recently, proteins. Here we propose that the atg8ylation is coopted by multiple downstream processes, one of which is canonical autophagy. We elaborate on these biological outputs, which impact metabolism, quality control, and immunity, emphasizing the context of inflammation and immunological effects. In conclusion, we propose that atg8ylation is a modification akin to ubiquitylation, and that it is utilized by different systems participating in membrane stress responses and membrane remodeling activities encompassing autophagy and beyond.

The multifaceted role of autophagy in cancer

Autophagy is a cellular degradative pathway that plays diverse roles in maintaining cellular homeostasis. Cellular stress caused by starvation, organelle damage, or proteotoxic aggregates can increase autophagy, which uses the degradative capacity of lysosomal enzymes to mitigate intracellular stresses. Early studies have shown a role for autophagy in the suppression of tumorigenesis. However, work in genetically engineered mouse models and in vitro cell studies have now shown that autophagy can be either cancer-promoting or inhibiting. Here, we summarize the effects of autophagy on cancer initiation, progression, immune infiltration, and metabolism. We also discuss the efforts to pharmacologically target autophagy in the clinic and highlight future areas for exploration.

The E3 Ligase TRIM16 Is a Key Suppressor of Pathological Cardiac Hypertrophy

Background: Pathological cardiac hypertrophy is one of the leading causes of heart failure with highly complicated pathogeneses. The E3 ligase TRIM16 (tripartite motif-containing protein 16) has been recognized as a pivotal regulator to control cell survival, immune response, and oxidative stress. However, the role of Trim16 in cardiac hypertrophy is unknown.

METHODS

We generated cardiac-specific knockout mice and adeno-associated virus serotype 9-Trim16 mice to evaluate the function of Trim16 in pathological myocardial hypertrophy. The direct effect of TRIM16 on cardiomyocyte enlargement was examined using an adenovirus system. Furthermore, we combined RNA-sequencing and interactome analysis that was followed by multiple molecular biological methodologies to identify the direct target and corresponding molecular events contributing to TRIM16 function.

RESULTS

We found an intimate correlation of Trim16 expression with hypertrophy-related heart failure in both human and mouse. Our functional investigations and unbiased transcriptomic analyses clearly demonstrated that Trim16 deficiency markedly exacerbated cardiomyocyte enlargement in vitro and in transverse aortic constriction-induced cardiac hypertrophy mouse model, whereas Trim16 overexpression attenuated cardiac hypertrophy and remodeling. Mechanistically, Prdx1 (peroxiredoxin 1) is an essential target of Trim16 in cardiac hypertrophy. We found that Trim16 interacts with Prdx1 and inhibits its phosphorylation, leading to a robust enhancement of its downstream Nrf2 (nuclear factor-erythroid 2-related factor 2) pathway to block cardiac hypertrophy. Trim16-blocked Prdx1 phosphorylation was largely dependent on a direct interaction between Trim16 and Src and the resultant Src ubiquitinational degradation. Notably, Prdx1 knockdown largely abolished the anti-hypertrophic effects of Trim16 overexpression.

CONCLUSIONS

Our findings provide the first evidence supporting Trim16 as a novel suppressor of pathological cardiac hypertrophy and indicate that targeting the Trim16-Prdx1 axis represents a promising therapeutic strategy for hypertrophy-related heart failure.

The Interplay between Autophagy and Redox Signaling in Cardiovascular Diseases

Reactive oxygen and nitrogen species produced at low levels under normal cellular metabolism act as important signal molecules. However, at increased production, they cause damage associated with oxidative stress, which can lead to the development of many diseases, such as cardiovascular, metabolic, neurodegenerative, diabetes, and cancer. The defense systems used to maintain normal redox homeostasis plays an important role in cellular responses to oxidative stress. The key players here are Nrf2-regulated redox signaling and autophagy. A tight interface has been described between these two processes under stress conditions and their role in oxidative stress-induced diseases progression. In this review, we focus on the role of Nrf2 as a key player in redox regulation in cell response to oxidative stress. We also summarize the current knowledge about the autophagy regulation and the role of redox signaling in this process. In line with the focus of our review, we describe in more detail information about the interplay between Nrf2 and autophagy pathways in myocardium and the role of these processes in cardiovascular disease development.

Identification of a tripartite motif family gene signature for predicting the prognosis of patients with glioma

Objectiove: The tripartite motif (TRIM) family genes, which encode a protein subfamily of the RING type E3 ubiquitin ligases, function as important regulators of oncogenesis and development. It is thus of great importance to investigate the potential value of the TRIM family genes for prognostic prediction in glioma.

METHODS

The gene expression RNA-Seq data and corresponding clinical information of glioma patients were obtained from The Cancer Genome Atlas (TCGA) dataset and the Chinese Glioma Genome Atlas (CGGA) dataset. LASSO regression and multivariate Cox regression analyses were performed to construct a risk signature of the TRIM family genes. The accuracy of the risk signature in predicting the prognosis of glioma patients was evaluated. The effects of TRIM17 on glioma cell proliferation were further explored.

RESULTS

We constructed a prognostic signature based on eight TRIMs for the prediction of overall survival of glioma patients. Internal and external cohorts confirmed the satisfactory accuracy and generalizability of the signature in predicting the prognosis of glioma patients. Of the eight TRIMs, TRIM17 was significantly downregulated in glioma, and decreased with an increase in the tumor grade. Moreover, low expression of TRIM17 predicted poor prognosis in glioma. CCK-8 and colony formation assays indicated that TRIM17 overexpression significantly inhibited cell proliferation. Conversely, silencing of TRIM17 had the opposite effects.

CONCLUSION

Our eight-gene signature based on the TRIM gene family is a novel and clinically useful biomarker, which may be helpful for clinical decision-making. Additionally, TRIM17 might be a therapeutic target for glioma.

E3 ligase Smurf1 protects against misfolded SOD1 in neuronal cells by promoting its K63 ubiquitylation and aggresome formation

K63-linked polyubiquitination of the neurodegenerative disease-associated misfolded protein copper-zinc superoxide dismutase (SOD1) is associated with the formation of inclusion bodies. Highly expressed E3 ligase Smurf1 promotes cellular homostasis through the enhanced capability of aggregate degradation. However, it is not well explored the role of Smurf1 in the dynamics of SOD1 aggresomes. In this study, we report that Smurf1 promotes the recruitment of SOD1 to form aggresomes. Mechanistically, Smurf1 interacts with mutant SOD1 to promote aggresome formation by modification of its K63-linked polyubiquitination. Moreover, overexpressed Smurf1 enhances mutant SOD1 aggresome formation and autophagic degradation to prevent cell death. Thus, our data suggest that Smurf1 plays an important role in attenuating protein misfolding-induced cell toxicity by both driving the sequestration of misfolded SOD1 into aggresomes and autophagic degradation.

Coronary Heart Disease in Type 2 Diabetes Mellitus: Genetic Factors and Their Mechanisms, Gene-Gene, and Gene-Environment Interactions in the Asian Populations

Asians are more susceptible to type 2 diabetes mellitus (T2D) and its coronary heart disease (CHD) complications than the Western populations, possibly due to genetic factors, higher degrees of obesity, insulin resistance, and endothelial dysfunction that could occur even in healthy individuals. The genetic factors and their mechanisms, along with gene-gene and gene-environment interactions associated with CHD in T2D Asians, are yet to be explored. Therefore, the objectives of this paper were to review the current evidence of genetic factors for CHD, summarize the proposed mechanisms of these genes and how they may associate with CHD risk, and review the gene-gene and gene-environment interactions in T2D Asians with CHD. The genetic factors can be grouped according to their involvement in the energy and lipoprotein metabolism, vascular and endothelial pathology, antioxidation, cell cycle regulation, DNA damage repair, hormonal regulation of glucose metabolism, as well as cytoskeletal function and intracellular transport. Meanwhile, interactions between single nucleotide polymorphisms (SNPs) from different genes, SNPs within a single gene, and genetic interaction with environmental factors including obesity, smoking habit, and hyperlipidemia could modify the gene's effect on the disease risk. Collectively, these factors illustrate the complexities of CHD in T2D, specifically among Asians.

Activation of p62-NRF2 Axis Protects against Doxorubicin-Induced Ferroptosis in Cardiomyocytes: A Novel Role and Molecular Mechanism of Resveratrol

Doxorubicin (DOX) is a most common anthracycline chemotherapeutic agent; however, its clinical efficacy is limited due to its severe and irreversible cardiotoxicity. Ferroptosis, characterized by iron overload and lipid peroxidation, plays a pivotal role in DOX-induced cardiotoxicity. Resveratrol (RSV) displays cardioprotective and anticancer effects, owing to its antioxidative and anti-inflammatory properties. However, the role and mechanism of RSV in DOX-mediated ferroptosis in cardiomyocytes is unclear. This study showed that DOX decreased cell viability, increased iron accumulation and lipid peroxidation in H9c2 cells; however, these effects were reversed by RSV and ferroptosis inhibitor ferrostatin-1 (Fer-1) pre-treatment. Additionally, RSV significantly increased the cell viability of H9c2 cells treated with ferroptosis inducers Erastin (Era) and RSL3. Mechanistically, RSV inhibited mitochondrial reactive oxygen species (mtROS) overproduction and upregulated the p62-NRF2/HO-1 pathway. RSV-induced NRF2 activation was partially dependent on p62, and the selective inhibition of p62 (using p62-siRNA interference) or NRF2 (using NRF2 specific inhibitor, ML385) significantly abolished the anti-ferroptosis function of RSV. Furthermore, RSV treatment protected mice against DOX-induced cardiotoxicity, including significantly improving left ventricular function, ameliorating myocardial fibrosis and suppressing ferroptosis. Consistent with in vitro results, RSV also upregulated the p62-NRF2/HO-1 expression, which was inhibited by DOX, in the myocardium. Notably, the protective effect of RSV in DOX-mediated ferroptosis was similar to that of Fer-1 in vitro and in vivo. Thus, the p62-NRF2 axis plays a critical role in regulating DOX-induced ferroptosis in cardiomyocytes. RSV as a potent p62 activator has potential as a therapeutic target in preventing DOX-induced cardiotoxicity via ferroptosis modulation.

A detrimental role of NLRP6 in host iron metabolism during Salmonella infection

Maintaining host iron homeostasis is an essential component of nutritional immunity responsible for sequestrating iron from pathogens and controlling infection. Nucleotide-oligomerization domain-like receptors (NLRs) contribute to cytoplasmic sensing and antimicrobial response orchestration. However, it remains unknown whether and how NLRs may regulate host iron metabolism, an important component of nutritional immunity. Here, we demonstrated that NLRP6, a member of the NLR family, has an unconventional role in regulating host iron metabolism that perturbs host resistance to bacterial infection. NLRP6 deficiency is advantageous for maintaining cellular iron homeostasis in both macrophages and enterocytes through increasing the unique iron exporter ferroportin-mediated iron efflux in a nuclear factor erythroid-derived 2–related factor 2 (NRF2)-dependent manner. Additional studies uncovered a novel mechanism underlying NRF2 regulation and operating through NLRP6/AKT interaction and that causes a decrease in AKT phosphorylation, which in turn reduces NRF2 nuclear translocation. In the absence of NLRP6, increased AKT activation promotes NRF2/KEAP1 dissociation via increasing mTOR-mediated p62 phosphorylation and downregulates KEAP1 transcription by promoting FOXO3A phosphorylation. Together, our observations provide new insights into the mechanism of nutritional immunity by revealing a novel function of NLRP6 in regulating iron metabolism, and suggest NLRP6 as a therapeutic target for limiting bacterial iron acquisition.

Tripartite motif-containing protein 16 protects against myocardial ischemia/reperfusion injury by affecting the Keap1/Nrf2 axis

Tripartite motif-containing protein (TRIM16) is a newly identified oxidative-stress-responsive protein. Oxidative stress is a hallmark of myocardial ischemia/reperfusion (I/R) injury and contributes to the cardiac injury. To date, whether TRIM16 plays a role in mediating oxidative stress during myocardial I/R injury is undetermined. The work is devoted to evaluate the possible relevance of TRIM16 in myocardial I/R injury. TRIM16 induction by myocardial hypoxia/reoxygenation (H/R) injury in vitro or myocardial I/R injury in vivo was observed. TRIM16 overexpression alleviated H/R-induced injury of rat cardiomyocytes. TRIM16 overexpression markedly attenuated cardiac injury, infarct size, and myocardial apoptosis induced by myocardial I/R injury. Further research revealed that TRIM16 was capable of enhancing Nrf2 activation via the regulation of Keap1. The inhibition of Nrf2 diminished TRIM16-overexpression-mediated cardioprotective effects. Overall, this work demonstrates that TRIM16 protects against myocardial I/R injury via affecting the Keap1/Nrf2 axis. This work offers new insights into the molecular mechanism underlying myocardial I/R injury and proposes TRIM16 as an attractive candidate target for cardioprotection.

LGALS3 (galectin 3) mediates an unconventional secretion of SNCA/α-synuclein in response to lysosomal membrane damage by the autophagic-lysosomal pathway in human midbrain dopamine neurons

Numerous lines of evidence support the premise that the misfolding and subsequent accumulation of SNCA/α-synuclein (synuclein alpha) is responsible for the underlying neuronal pathology observed in Parkinson disease (PD) and other synucleinopathies. Moreover, the cell-to-cell transfer of these misfolded SNCA species is thought to be responsible for disease progression and the spread of cellular pathology throughout the brain. Previous work has shown that when exogenous, misfolded SNCA fibrils enter cells through endocytosis, they can damage and rupture the membranes of their endocytotic vesicles in which they are trafficked. Rupture of these vesicular membranes exposes intralumenal glycans leading to galectin protein binding, subsequent autophagic protein recruitment, and, ultimately, their introduction into the autophagic-lysosomal pathway. Increasing evidence indicates that both pathological and non-pathological SNCA species undergo autophagy-dependent unconventional secretion. While other proteins have also been shown to be secreted from cells by autophagy, what triggers this release process and how these specific proteins are recruited to a secretory autophagic pathway is largely unknown. Here, we use a human midbrain dopamine (mDA) neuronal culture model to provide evidence in support of a cellular mechanism that explains the cell-to-cell transfer of pathological forms of SNCA that are observed in PD. We demonstrate that LGALS3 (galectin 3) mediates the release of SNCA following vesicular damage. SNCA release is also dependent on TRIM16 (tripartite motif containing 16) and ATG16L1 (autophagy related 16 like 1), providing evidence that secretion of SNCA is mediated by an autophagic secretory pathway.

Identification of a TRIM32 from Penaeus monodon is involved in autophagy and innate immunity during white spot syndrome virus infection

Many tripartite motif (TRIM) family proteins played an important role in regulating innate immune and autophagy pathway and were important for host defenses against viral pathogens. However, the role of TRIM proteins in autophagy and innate immunity during virus infection was seldom studied in crustaceans. In this study, a novel TRIM32 homolog was identified from Penaeus monodon (named PmTRIM32). PmTRIM32 was significantly upregulated by rapamycin stimulation and WSSV infection. RNA interference experiments showed that PmTRIM32 could restrict WSSV replication and lead P. monodon more resistance to WSSV challenge. Autophagy could be induced by WSSV or rapamycin challenge and has been proved to play a positive role in restricting WSSV replication in P. monodon. The autophagy activity induced by WSSV or rapamycin challenge could be obviously inhibited by silence of PmTRIM32 in P. monodon. Further studies revealed that PmTRIM32 positively regulated the expression of nuclear transcription factor (NF-κB) and it mediated antimicrobial peptides. Moreover, Pull-down and in vitro ubiquitination assay demonstrated that PmTRIM32 could interact with WSSV envelope protein and target it for ubiquitination in vitro. Collectively, this study demonstrated that PmTRIM32 restricted WSSV replication and was involved in positively regulating autophagy and NF-κB pathway during WSSV infection in P. monodon.

TRIM16 overexpression inhibits the metastasis of colorectal cancer through mediating Snail degradation

Tripartite motif containing 16 (TRIM16) is a member of the tripartite motif protein family and functions as a potential tumor suppressor in several cancers. However, the specific function and clinical significance of TRIM16 in colorectal cancer (CRC) remains unclear. In this study, we observed that low TRIM16 expression was detected frequently in primary colorectal cancer (CRC) tissues and was closely associated with a better prognosis. Functional studies demonstrate that TRIM16 overexpression notably inhibits the metastasis abilities of CRC in vivo and in vitro. Mechanistically, our results demonstrated that TRIM16 directly bound and ubiquitinated Snail family transcriptional repressor 1 (Snail), an important transcriptional factor of the epithelial-mesenchymal transition (EMT) process suppressing the EMT in CRC. Additionally, our data revealed that the inhibition effect of TRIM16 on cancer metastasis was dependent on Snail degradation. Collectively, our study is the first to report that TRIM16 plays a crucial anti-tumor role in CRC tumorigenesis. We also provided novel evidence that TRIM16 might act as a prognostic and therapeutic target to assess and inhibit CRC progression.

Tripartite motif 16 ameliorates nonalcoholic steatohepatitis by promoting the degradation of phospho-TAK1

Nonalcoholic steatohepatitis (NASH)-related hepatocellular carcinoma and liver disorders have become the leading causes for the need of liver transplantation in developed countries. Lipotoxicity plays a central role in NASH progression by causing endoplasmic reticulum stress and disrupting protein homeostasis. To identify key molecules that mitigate the detrimental consequences of lipotoxicity, we performed integrative multiomics analysis and identified the E3 ligase tripartite motif 16 (TRIM16) as a candidate molecule. In particular, we found that lipid accumulation and inflammation in a mouse NASH model is mitigated by TRIM16 overexpression but aggravated by its depletion. Multiomics analysis showed that TRIM16 suppressed NASH progression by attenuating the activation of the mitogen-activated protein kinase (MAPK) signaling pathway; specifically, by preferentially interacting with phospho-TAK1 to promote its degradation. Together, these results identify TRIM16 as a promising therapeutic target for the treatment of NASH.

The intestinal microbiota contributes to the growth and physiological state of muscle tissue in piglets

Although the importance of the intestinal microbiota in host growth and health is well known, the relationship between microbiota colonization and muscle development is unclear. In this study, the direct causal effects of the colonization of gut microorganisms on the muscle tissue of piglets were investigated. The body weight and lean mass of germ-free (GF) piglets were approximately 40% lower than those of normal piglets. The deletion of the intestinal microbiota led to weakened muscle function and a reduction in myogenic regulatory proteins, such as MyoG and MyoD, in GF piglets. In addition, the blinded IGF1/AKT/mTOR pathway in GF piglets caused muscle atrophy and autophagy, which were characterized by the high expression of Murf-1 and KLF15. Gut microbiota introduced to GF piglets via fecal microbiota transplantation not only colonized the gut but also partially restored muscle growth and development. Furthermore, the proportion of slow-twitch muscle fibers was lower in the muscle of GF piglets, which was caused by the reduced short-chain fatty acid content in the circulation and impaired mitochondrial function in muscle. Collectively, these findings suggest that the growth, development and function of skeletal muscle in animals are mediated by the intestinal microbiota.

Identification of a Shrimp E3 Ubiquitin Ligase TRIM50-Like Involved in Restricting White Spot Syndrome Virus Proliferation by Its Mediated Autophagy and Ubiquitination

Most tripartite motif (TRIM) family proteins are critical components of the autophagy machinery and play important roles in host defense against viral pathogens in mammals. However, the roles of TRIM proteins in autophagy and viral infection have not been studied in lower invertebrates, especially crustaceans. In this study, we first identified a TRIM50-like gene from Penaeus monodon (designated PmTRIM50-like), which, after a white spot syndrome virus (WSSV) challenge, was significantly upregulated at the mRNA and protein levels in the intestine and hemocytes. Knockdown of PmTRIM50-like led to an increase in the WSSV quantity in shrimp, while its overexpression led to a decrease compared with the controls. Autophagy can be induced by WSSV or rapamycin challenge and has been shown to play a positive role in restricting WSSV replication in P. monodon. The mRNA and protein expression levels of PmTRIM50-like significantly increased with the enhancement of rapamycin-induced autophagy. The autophagy activity induced by WSSV or rapamycin challenge could be inhibited by silencing PmTRIM50-like in shrimp. Further studies showed that rapamycin failed to induce autophagy or inhibit WSSV replication after knockdown of PmTRIM50-like. Moreover, pull-down and in vitro ubiquitination assays demonstrated that PmTRIM50-like could interact with WSSV envelope proteins and target them for ubiquitination in vitro. Collectively, this study demonstrated that PmTRIM50-like is required for autophagy and is involved in restricting the proliferation of WSSV through its ubiquitination. This is the first study to report the role of a TRIM family protein in virus infection and host autophagy in crustaceans.

Nrf2 modulated the restriction of lung function via impairment of intrinsic autophagy upon real-ambient PM2.5 exposure

Compelling studies approve that fine particle matter (PM_2.5) exposure was associated with high risk of respiratory disorders. However, the available data assessing the detailed influence of PM_2.5 on lung was limited. To overcome the difficulty of inhalational PM_2.5 exposure, the real-ambient PM_2.5 exposure system was constructed. The mice were exposed to filtered air (FA) or real-ambient PM_2.5 (PM_2.5), and the adverse effect on lung was determined. Nuclear factor E2-related factor 2 (Nrf2) as a transcription factor, was reported to affect autophagy. Autophagy was proposed as a two-edge sword in respiratory disorders. Here, our data presented that PM_2.5 exposure dramatically reduced the lung function of WT mice rather than Nrf2^-/- mice. Consistently, thickened alveolar walls was observed in WT mice in PM_2.5 exposure group, whereas the histological phenotype of Nrf2^-/- mice exhibited no obvious alteration. Furthermore, PM_2.5 exposure triggered low-grade production of inflammatory profile in WT and Nrf2^-/- mice. Moreover, the protein levels of p62, Beclin1 and LC3B of WT mice rather than Nrf2^-/- mice were also altered in PM_2.5 exposure group. Taken together, the present study applied the real-ambient exposure system, revealed the adverse effect of air pollution on lung, and proposed the underlying mechanism.

Upregulation of antioxidant and autophagy pathways via NRF2 activation protects spinal cord neurons from ozone damage

Ozone therapy can relieve multiple types of pain but exhibits potential neurotoxicity, the mechanism of which is unclear. The present study aimed to identify the role of nuclear factor (erythroid-derived-2)-related 2 (NRF2) in preventing spinal cord injury caused by ozone overdose. Primary neuronal cells were extracted from newborn Wistar rats and authenticated by immunofluorescence using anti-microtubule-associated protein 2 as a cell type-specific marker. Cell viability assay with different ozone concentrations (0, 10, 20, 30 and 40 µg/ml) was used to determine the concentration that caused primary neuron injury; 30 min of 40 µg/ml ozone therapy notably decreased cell viability to 71%. In order to test the effects of ozone, the cells were divided into five treatment groups [0-, 30- and 40 µg/ml ozone, tert-butylhydroquinone (tBHQ) + 40 µg/ml ozone (T40) and tBHQ (T0)]. Cells in the T40 and T0 groups received 40 µmol/l tBHQ on the fifth day of SCN cultivation. Reverse transcription-quantitative PCR and western blotting showed that protein expression levels of heme oxygenase-1 (HO-1) and mRNA expression levels of HO-1 and NRF2 were decreased. NRF2, ubiquitin-binding protein p62 and microtubule-associated proteins 1A/1B light chain 3B expression levels were decreased following treatment with 40 µg/ml ozone. Immunofluorescence showed that NRF2 nuclear expression levels also decreased following 40 µg/ml ozone treatment. However, cells in the T40 group did not display decreased NRF2 nuclear expression levels. Normal/Apoptotic/Necrotic Cell Detection kit revealed that necrosis rate increased following treatment with 40 µg/ml ozone; however, the T40 group did not exhibit this increased necrosis. At 40 µg/ml, ozone increased spinal cord neuron (SCN) death in vitro. Moreover, treatment with 40 µg/ml ozone damaged SCNs. The p62/NRF2/antioxidant response element pathway prevented such injury. tBHQ activated this pathway, upregulated autophagy and increased local nuclear NRF2 concentration, thus enhancing the antioxidant system to protect SCNs from injury caused by high concentrations of ozone.

TRIM39 deficiency inhibits tumor progression and autophagic flux in colorectal cancer via suppressing the activity of Rab7

The biological function of TRIM39, a member of TRIM family, remains largely unexplored in cancer, especially in colorectal cancer (CRC). In this study, we show that TRIM39 is upregulated in tumor tissues compared to adjacent normal tissues and associated with poor prognosis in CRC. Functional studies demonstrate that TRIM39 deficiency restrains CRC progression in vitro and in vivo. Our results further find that TRIM39 is a positive regulator of autophagosome–lysosome fusion. Mechanistically, TRIM39 interacts with Rab7 and promotes its activity via inhibiting its ubiquitination at lysine 191 residue. Depletion of TRIM39 inhibits CRC progression and autophagic flux in a Rab7 activity-dependent manner. Moreover, TRIM39 deficiency suppresses CRC progression through inhibiting autophagic degradation of p53. Thus, our findings uncover the roles as well as the relevant mechanisms of TRIM39 in CRC and establish a functional relationship between autophagy and CRC progression, which may provide promising approaches for the treatment of CRC.