TRAF6 Restricts p53 Mitochondrial Translocation, Apoptosis, and Tumor Suppression

Understanding the complexity of p53 in a new era of tumor suppression

p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.

Drug delivery system based on metal-organic framework improved 5-Fluorouracil against spring viremia of carp virus

Spring viremia of carp virus (SVCV), as a high pathogenicity pathogen, has seriously restricts the healthy and sustainable development of cyprinid farming industry. In this study, we selected 5-Fluorouracil (5-Fu) as the drug model based on zeolitic imidazolate framework-8 (ZIF-8) to construct a drug delivery system (5-Fu@ZIF-8), and the anti-SVCV activity was detected in vitro and in vivo. The results showed 5-Fu@ZIF-8 was uniform cubic particle with truncated angle and smooth surface, and the particle size was 90 nm. The anti-SVCV activity in vitro results showed that the highest inhibition rate of 5-Fu was 77.93% at 40 mg/L and the inhibitory concentration at half-maximal activity (IC50) was 20.86 mg/L. For 5-Fu@ZIF-8, the highest inhibition rate was 91.36% at 16 mg/L, and the IC50 value was 5.85 mg/L. In addition, the cell viability was increased by 18.1% after 5-Fu treatment. Similarly, after 5-Fu@ZIF-8 treatment, the cell viability increased by 27.3%. Correspondingly, in vivo experimental results showed the viral loads reduced by 18.1% on the days 7 and the survival rate increased to 19.4% at 80 mg/L after 5-Fu treatment. For 5-Fu@ZIF-8, the viral loads reduced by 41.2% and the survival rate increased to 54.8%. Mechanistically, 5-Fu inhibits viral replication by regulating p53 expression and promoting early apoptosis in infected cells. All results indicated that 5-Fu@ZIF-8 improved the anti-SVCV activity; it may be a potential strategy to construct a drug-loaded system with ZIF-8 as a carrier for the prevention and treatment of aquatic diseases.

The cross talk of ubiquitination and chemotherapy tolerance in colorectal cancer

Ubiquitination, a highly adaptable post-translational modification, plays a pivotal role in maintaining cellular protein homeostasis, encompassing cancer chemoresistance-associated proteins. Recent findings have indicated a potential correlation between perturbations in the ubiquitination process and the emergence of drug resistance in CRC cancer. Consequently, numerous studies have spurred the advancement of compounds specifically designed to target ubiquitinates, offering promising prospects for cancer therapy. In this review, we highlight the role of ubiquitination enzymes associated with chemoresistance to chemotherapy via the Wnt/β-catenin signaling pathway, epithelial-mesenchymal transition (EMT), and cell cycle perturbation. In addition, we summarize the application and role of small compounds that target ubiquitination enzymes for CRC treatment, along with the significance of targeting ubiquitination enzymes as potential cancer therapies.

Structure-guided engineering enables E3 ligase-free and versatile protein ubiquitination via UBE2E1

Ubiquitination, catalyzed usually by a three-enzyme cascade (E1, E2, E3), regulates various eukaryotic cellular processes. E3 ligases are the most critical components of this catalytic cascade, determining both substrate specificity and polyubiquitination linkage specificity. Here, we reveal the mechanism of a naturally occurring E3-independent ubiquitination reaction of a unique human E2 enzyme UBE2E1 by solving the structure of UBE2E1 in complex with substrate SETDB1-derived peptide. Guided by this peptide sequence-dependent ubiquitination mechanism, we developed an E3-free enzymatic strategy SUE1 (sequence-dependent ubiquitination using UBE2E1) to efficiently generate ubiquitinated proteins with customized ubiquitinated sites, ubiquitin chain linkages and lengths. Notably, this strategy can also be used to generate site-specific branched ubiquitin chains or even NEDD8-modified proteins. Our work not only deepens the understanding of how an E3-free substrate ubiquitination reaction occurs in human cells, but also provides a practical approach for obtaining ubiquitinated proteins to dissect the biochemical functions of ubiquitination.

A circRNA therapy based on Rnf103 to inhibit Vibrio anguillarum infection

The losses caused by Vibrio infections in the aquaculture industry are challenging to quantify. In the face of antibiotic resistance, a natural and environmentally friendly alternative is urgently needed. In this study, we identify E3 ubiquitin-protein ligase RNF103 (rnf103) as a crucial target involved in immune evasion by Vibrio anguillarum. Our research demonstrates that Rnf103 promotes immune escape by inhibiting Traf6. Interestingly, we discover a circular RNA (circRNA), circRnf103, formed by reverse splicing of the Rnf103 gene. Predictive analysis and experimentation reveal that circRnf103 encodes Rnf103-177aa, a protein that competes with Rnf103 and binds to Traf6, preventing its degradation. Notably, circRnf103 therapy induces Rnf103-177aa protein production in zebrafish. In zebrafish models, circRnf103 exhibits significant effectiveness in treating V. anguillarum infections, reducing organ burden. These findings highlight the potential of circRNA therapy as a natural and innovative approach to combat infectious diseases sustainably, particularly in aquaculture and environmental management.

Large-scale lysine crotonylation analysis reveals the role of TRAF6-Ecsit complex in endoplasmic reticulum stress in mud crab (Scylla paramamosain)

Lysine crotonylation (Kcr) is a newly discovered type of post-translational modification. Although Kcr has been reported in several species, its role in crustaceans remains largely unknown. In this study, Kcr in hemocytes of mud crab (Scylla paramamosain) was characterized using pan anti-crotonyllysine antibody enrichment and high-resolution liquid chromatogram-mass spectrometry analysis after SpTRAF6 or SpEcsit silencing. Altogether, 1,800 Kcr sites with six conserved motifs were identified from 512 proteins. Subcellular localization analysis showed that the identified Kcr proteins were mainly localized to the cytoplasm, nucleus, and mitochondria. The cellular components analysis showed that the 'chromosomal region' was enriched in the hemocytes of SpTRAF6-or SpEcsit-silenced mud crabs. The KEGG and PPI analyses showed that the identified Kcr proteins in the hemocytes SpTRAF6-or SpEcsit-silenced mud crabs were related to the 'protein processing in endoplasmic reticulum'; of which the marker of endoplasmic reticulum stress (Bip) was identified to be crotonylated. These datasets present the first comprehensive analysis of the crotonylome in mud crab hemocytes, providing invaluable insights into the regulatory functions of SpTRAF6 and SpEcsit in Kcr. Additionally, our findings shed light on the potential role of these proteins in activating marker proteins during endoplasmic reticulum stress in invertebrates.

p53 at the crossroad between mitochondrial reactive oxygen species and necroptosis

p53 is a redox-sensitive transcription factor that can regulate multiple cell death programs through different signaling pathways. In this review, we assess the role of p53 in the regulation of necroptosis, a programmed form of lytic cell death highly involved in the pathophysiology of multiple diseases. In particular, we focus on the role of mitochondrial reactive oxygen species (mtROS) as essential contributors to modulate necroptosis execution through p53. The enhanced generation of mtROS during necroptosis is critical for the correct interaction between receptor-interacting serine/threonine-protein kinase 1 (RIPK1) and 3 (RIPK3), two key components of the functional necrosome. p53 controls the occurrence of necroptosis by modulating the levels of mitochondrial H2O2 via peroxiredoxin 3 and sulfiredoxin. Furthermore, in response to increased levels of H2O2, p53 upregulates the long non-coding RNA necrosis-related factor, favoring the translation of RIPK1 and RIPK3. In parallel, a fraction of cytosolic p53 migrates into mitochondria, a process notably involved in necroptosis execution via its interaction with the mitochondrial permeability transition pore. In conclusion, p53 is located at the intersection between mtROS and the necroptosis machinery, making it a key protein to orchestrate redox signaling during necroptosis.

TRAF6 regulates autophagy and apoptosis of melanoma cells through c-Jun/ATG16L2 signaling pathway

Autophagy and apoptosis are essential processes that participate in cell death and maintain cellular homeostasis. Dysregulation of these biological processes results in the development of diseases, including cancers. Therefore, targeting the interaction between apoptosis and autophagy offers a potential strategy for cancer therapy. Melanoma is the most lethal skin cancer. We previously found that tumor necrosis factor receptor-associated factor 6 (TRAF6) is overexpressed in melanoma and benefits the malignant phenotype of melanoma cells. Additionally, TRAF6 promotes the activation of cancer-associated fibroblasts in melanoma. However, the role of TRAF6 in autophagy and apoptosis remains unclear. In this study, we found that knockdown of TRAF6 induced both apoptosis and autophagy in melanoma cells. Transcriptomic data and real-time PCR analysis demonstrated reduced expression of autophagy related 16 like 2 (ATG16L2) in TRAF6-deficient melanoma cells. ATG16L2 knockdown resulted in increased autophagy and apoptosis. Mechanism studies confirmed that TRAF6 regulated ATG16L2 expression through c-Jun. Importantly, targeting TRAF6 with cinchonine, a TRAF6 inhibitor, effectively suppressed the growth of melanoma cells by inducing autophagy and apoptosis through the TRAF6/c-Jun/ATG16L2 signaling pathway. These findings highlight the pivotal role of TRAF6 in regulating autophagy and apoptosis in melanoma, emphasizing its significance as a novel therapeutic target for melanoma treatment.

Lysine methylation promotes NFAT5 activation and determines temozolomide efficacy in glioblastoma

Temozolomide (TMZ) therapy offers minimal clinical benefits in patients with glioblastoma multiforme (GBM) with high EGFR activity, underscoring the need for effective combination therapy. Here, we show that tonicity-responsive enhancer binding protein (NFAT5) lysine methylation, is a determinant of TMZ response. Mechanistically, EGFR activation induces phosphorylated EZH2 (Ser21) binding and triggers NFAT5 methylation at K668. Methylation prevents NFAT5 cytoplasm interaction with E3 ligase TRAF6, thus blocks NFAT5 lysosomal degradation and cytosol localization restriction, which was mediated by TRAF6 induced K63-linked ubiquitination, resulting in NFAT5 protein stabilization, nuclear accumulation and activation. Methylated NFAT5 leads to the upregulation of MGMT, a transcriptional target of NFAT5, which is responsible for unfavorable TMZ response. Inhibition of NFAT5 K668 methylation improved TMZ efficacy in orthotopic xenografts and patient-derived xenografts (PDX) models. Notably, NFAT5 K668 methylation levels are elevated in TMZ-refractory specimens and confer poor prognosis. Our findings suggest targeting NFAT5 methylation is a promising therapeutic strategy to improve TMZ response in tumors with EGFR activation.

IKK-mediated TRAF6 and RIPK1 interaction stifles cell death complex assembly leading to the suppression of TNF-α-induced cell death

Tumor necrosis factor α (TNF-α) is a pro-inflammatory cytokine capable of inducing extrinsic apoptosis and necroptosis. Tumor necrosis factor receptor-associated factor 6 (TRAF6), an E3 ligase, is a member of the TRAF family of proteins, which mediates inflammatory signals by activating nuclear factor kappa B (NFкB) and mitogen-activated protein kinase (MAPK). Although the functions of TRAF6 have been identified, its role in TNF-α-induced cell death remains poorly understood. Here, we report that TRAF6 is a negative modulator of TNF-α-induced cell death but does not affect TNF-α-induced NFκB activation. TRAF6 deficiency accelerates both TNF-α-induced apoptosis and necroptosis; however, the acceleration can be reversed by reconstituting TRAF6 or TRAF6C70A, suggesting that E3 ligase activity is not required for this activity. Mechanistically, TRAF6 directly interacts with RIPK1 during TNF-α-induced cell death signaling, which prevents RIPK1 from interacting with components of the cell death complex such as itself, FADD or RIPK3. These processes suppress the assembly of the death complex. Notably, IKK was required for TRAF6 to interact with RIPK1. In vivo, Traf6-/- embryos exhibited higher levels of cell death in the liver but could be rescued by the simultaneous knockout of Tnf. Finally, TRAF6 knockdown xenografts were highly sensitive to necroptotic stimuli. We concluded that TRAF6 suppresses TNF-α-induced cell death in coordination with IKK complexes in vivo and in vitro by suppressing the assembly of cell death complex.

Targeting BRD3 eradicates nuclear TYRO3-induced colorectal cancer metastasis

Metastasis is the main cause of death in many cancers including colorectal cancer (CRC); however, the underlying mechanisms responsible for metastatic progression remain largely unknown. We found that nuclear TYRO3 receptor tyrosine kinase is a strong predictor of poor overall survival in patients with CRC. The metastasis-promoting function of nuclear TYRO3 requires its kinase activity and matrix metalloproteinase-2 (MMP-2)-mediated cleavage but is independent of ligand binding. Using proteomic analysis, we identified bromodomain-containing protein 3 (BRD3), an acetyl-lysine reading epigenetic regulator, as one of nuclear TYRO3's substrates. Chromatin immunoprecipitation-sequencing data reveal that TYRO3-phosphorylated BRD3 regulates genes involved in anti-apoptosis and epithelial-mesenchymal transition. Inhibition of MMP-2 or BRD3 activity by selective inhibitors abrogates nuclear TYRO3-induced drug resistance and metastasis in organoid culture and in orthotopic mouse models. These data demonstrate that MMP-2/TYRO3/BRD3 axis promotes the metastasis of CRC, and blocking this signaling cascade is a promising approach to ameliorate CRC malignancy.

Non-coding RNAs targeting NF-κB pathways in aquatic animals: A review

Nuclear factor-kappa B (NF-κB) pathways have a close relationship with many diseases, especially in terms of the regulation of inflammation and the immune response. Non-coding RNAs (ncRNAs) are a heterogeneous subset of endogenous RNAs that directly affect cellular function in the absence of proteins or peptide products; these include microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), etc. Studies on the roles of ncRNAs in targeting the NF-κB pathways in aquatic animals are scarce. A few research studies have confirmed detailed regulatory mechanisms among ncRNAs and the NF-κB pathways in aquatic animals. This comprehensive review is presented concerning ncRNAs targeting the NF-κB pathway in aquatic animals and provides new insights into NF-κB pathways regulatory mechanisms of aquatic animals. The review discusses new possibilities for developing non-coding-RNA-based antiviral applications in fisheries.

Role of K63-linked ubiquitination in cancer

Ubiquitination is a critical type of post-translational modifications, of which K63-linked ubiquitination regulates interaction, translocation, and activation of proteins. In recent years, emerging evidence suggest involvement of K63-linked ubiquitination in multiple signaling pathways and various human diseases including cancer. Increasing number of studies indicated that K63-linked ubiquitination controls initiation, development, invasion, metastasis, and therapy of diverse cancers. Here, we summarized molecular mechanisms of K63-linked ubiquitination dictating different biological activities of tumor and highlighted novel opportunities for future therapy targeting certain regulation of K63-linked ubiquitination in tumor.

[TRAF6 promotes Bacillus Calmette-Guérin-induced macrophage apoptosis through the intrinsic apoptosis pathway]

OBJECTIVE

To investigate the role of tumor necrosis factor receptor-associated factor 6 (TRAF6) in regulating Bacillus Calmette-Guérin (BCG)-induced macrophage apoptosis.

METHODS

The expression of TRAF6 in peripheral blood samples of 50 patients with active tuberculosis (TB) and 50 healthy individuals were detected using quantitative real-time PCR (qPCR). RAW264.7 macrophages were infected with BCG at different MOI and for different lengths of time, and the changes in expressions of Caspase 3 and TRAF6 were detected with Western blotting and qPCR. In a RAW264.7 cell model of BCG infection with TRAF6 knockdown established using RNA interference technique, the bacterial load was measured and cell apoptotic rate and mitochondrial membrane potential (MMP) were determined with flow cytometry. The expression levels of TRAF6, Caspase 3, PARP, BAX and Bcl-2 in the cells were detected using Western blotting, and the expressions of TRAF6 and Caspase 3 were also examined with immunofluorescence assay.

RESULTS

The expression of TRAF6 was significantly upregulated in the peripheral blood of patients with active TB as compared with healthy subjects (P < 0.001). In RAW264.7 cells, BCG infection significantly increased the expressions of Caspase 3 and TRAF6, which were the highest in cells infected for 18 h and at the MOI of 15. TRAF6 knockdown caused a significant increase of bacterial load in BCG-infected macrophages (P=0.05), lowered the cell apoptotic rate (P < 0.001) and reduced the expressions of Caspase 3 (P=0.002) and PARP (P < 0.001). BCG-infected RAW264.7 cells showed a significantly increased MMP (P < 0.001), which was lowered by TRAF6 knockdown (P < 0.001); the cells with both TRAF6 knockdown and BCG infection showed a lowered BAX expression (P=0.005) and an increased expression of Bcl-2 (P=0.04).

CONCLUSION

TRAF6 promotes BCG-induced macrophage apoptosis by regulating the intrinsic apoptosis pathway.

p53 ubiquitination co-mediated by HUWE1 and TRAF6 contributes to WSSV infection in crustacean

p53, the guardian of the genome, is a short-lived protein that is tightly controlled at low levels by constant ubiquitination and proteasomal degradation in higher organisms. p53 stabilization and activation are early crucial events to cope with external stimuli in cells. However, the role of p53 ubiquitination and its relevant molecular mechanisms have not been addressed in invertebrates. In this study, our findings revealed that both HUWE1 (HECT, UBA, and WWE domain-containing E3 ubiquitin-protein ligase 1) and TRAF6 (tumor necrosis factor receptor-associated factor 6) could serve as E3 ubiquitin ligases for p53 in mud crabs (Scylla paramamosain). Moreover, the expression of HUWE1 and TRAF6 was significantly downregulated during white spot syndrome virus (WSSV) infection, and therefore the ubiquitination of p53 was interrupted, leading to the activation of apoptosis and reactive oxygen species (ROS) signals through p53 accumulation, which eventually suppressed viral invasion in the mud crabs. To the best of our knowledge, this is the first study to reveal the p53 ubiquitination simultaneously induced by two E3 ligases in arthropods, which provides a novel molecular mechanism of invertebrates for resistance to viral infection.

IMPORTANCE p53, which is a well-known tumor suppressor that has been widely studied in higher animals, has been reported to be tightly controlled at low levels by ubiquitin-dependent proteasomal degradation. However, recent p53 ubiquitination-relevant research mainly involved an individual E3 ubiquitin ligase, but not whether there exist other mechanisms that need to be explored. The results of this study show that HUWE1 and TRAF6 could serve as p53 E3 ubiquitin ligases and synchronously mediate p53 ubiquitination in mud crabs (Scylla paramamosain), which confirmed the diversity of the p53 ubiquitination regulatory pathway. In addition, the effects of p53 ubiquitination are mainly focused on tumorigenesis, but a few are focused on the host immune defense in invertebrates. Our findings reveal that p53 ubiquitination could affect ROS and apoptosis signals to cope with WSSV infection in mud crabs, which is the first clarification of the immunologic functions and mechanisms of p53 ubiquitination in invertebrates.

Targeting Post-Translational Regulation of p53 in Colorectal Cancer by Exploiting Vulnerabilities in the p53-MDM2 Axis

The role played by the key tumor suppressor gene p53 and the implications of p53 mutations for the development and progression of neoplasia continue to expand. This review focuses on colorectal cancer and the regulators of p53 expression and activity identified over the past decade. These newly recognized regulatory mechanisms include (1) direct regulation of mouse double minute 2 homolog (MDM2), an E3 ubiquitin-protein ligase; (2) modulation of the MDM2-p53 interaction; (3) MDM2-independent p53 degradation; and (4) inhibition of p53 nuclear translocation. We positioned these regulatory mechanisms in the context of p53 missense mutations, which not only evade canonical p53 degradation machinery but also exhibit gain-of-function phenotypes that enhance tumor survival and metastasis. Lastly, we discuss current and potential therapeutic strategies directed against p53 mutant-bearing tumors.

Killing by Degradation: Regulation of Apoptosis by the Ubiquitin-Proteasome-System

Apoptosis is a cell suicide process that is essential for development, tissue homeostasis and human health. Impaired apoptosis is associated with a variety of human diseases, including neurodegenerative disorders, autoimmunity and cancer. As the levels of pro- and anti-apoptotic proteins can determine the life or death of cells, tight regulation of these proteins is critical. The ubiquitin proteasome system (UPS) is essential for maintaining protein turnover, which can either trigger or inhibit apoptosis. In this review, we will describe the E3 ligases that regulate the levels of pro- and anti-apoptotic proteins and assisting proteins that regulate the levels of these E3 ligases. We will provide examples of apoptotic cell death modulations using the UPS, determined by positive and negative feedback loop reactions. Specifically, we will review how the stability of p53, Bcl-2 family members and IAPs (Inhibitor of Apoptosis proteins) are regulated upon initiation of apoptosis. As increased levels of oncogenes and decreased levels of tumor suppressor proteins can promote tumorigenesis, targeting these pathways offers opportunities to develop novel anti-cancer therapies, which act by recruiting the UPS for the effective and selective killing of cancer cells.

TRAF7 contributes to tumor progression by promoting ubiquitin-proteasome mediated degradation of P53 in hepatocellular carcinoma

It has been proved that TRAFs family proteins played malfunctioning roles in the development of human cancers. TRAF7 is the last one of TRAFs family proteins to be found, which was demonstrated to be involved in a serious of cancers development. In this study, we systematically investigated the molecular mechanisms of TRAF7 in facilitating hepatocellular carcinoma (HCC). We discovered that TRAF7 was overexpressed in tumor tissues and the increased TRAF7 expression was closely associated with tumor size, histologic grade, TNM stage and poor prognostication. TRAF7 overexpression repressed cell apoptosis and promoted cell proliferation, invasion and migration, whereas knockdown of TRAF7 in HCC cells had totally opposite effects. Besides, we identified the interaction between TRAF7 and P53 in HCC and demonstrated that TRAF7 promoted ubiquitin-proteasome mediated degradation of P53 at K48 site. The rescue assays further proved that the function of TRAF7 in inhibiting apoptosis and promoting tumor development was depended on P53 in HCC. Overall, this work identified that TARF7 promoted tumorigenesis by targeted degradation P53 for ubiquitin-mediated proteasome pathway. Targeting the TRAF7-P53 axis may provide new insights in the pathogenesis of HCC, and pave the way for developing novel strategies for HCC prevention and treatment.

MicroRNA-146b-5p suppresses cholangiocarcinoma cells by targeting TRAF6 and modulating p53 translocation

BACKGROUND

In view of the poor prognosis and high mortality of cholangiocarcinoma, there is a need for new therapeutic strategies. This study aims to reveal the biological function of miR-146b-5p in cholangiocarcinoma cell and its possible mechanism.

METHODS

The expression level and prognostic information on miR-146b-5p in cholangiocarcinoma were obtained in TCGA database. The biological function of miR-146b-5p on proliferation and vitality of cholangiocarcinoma cell HUCCT-1 was examined by EdU and MTT assay, and the apoptosis of HUCCT-1 cells transfected with miR-146b-5p mimic, mimic control, inhibitor, inhibitor control was detected by flow cytometry analysis. The western blot was done to evaluate the effect of miR-146b-5p targeting substrate and the expression of p53 in whole-cell protein and mitochondria fractions.

RESULTS

Our finding revealed that miR-146b-5p expression in patients with CHOL was lower than the normal group(p＜0.001). MiR-146b-5p expression was down-regulated in human cholangiocarcinoma HUCCT-1 and RBE cells compared to normal control HIBEC and other cancer cells. The miR-146b-5p mimic could inhibit HUCCT-1 cell proliferation (p＜0.05) and promote HUCCT-1 cell apoptosis significantly (p＜0.05). The results of western blot showed that miR-146b-5p mimic could directly target TRAF6 3'UTR region and up-regulate the expression of p53 in mitochondria and miR-146b-5p inhibitor could down-regulated the level of p53 in mitochondria.

CONCLUSION

MiR-146b-5p is a cholangiocarcinoma suppressor by inhibiting cell proliferation and promoting cell apoptosis with targeting TRAF6, possibly via modulating p53 translocation to mitochondria.

The circular RNA circBCL2L1 regulates innate immune responses via microRNA-mediated downregulation of TRAF6 in teleost fish

Growing numbers of studies have shown that circular RNAs (circRNAs) can function as regulatory factors to regulate the innate immune response, cell proliferation, cell migration, and other important processes in mammals. However, the function and regulatory mechanism of circRNAs in lower vertebrates are still unclear. Here, we discovered a novel circRNA derived from the gene encoding Bcl-2-like protein 1 (BCL2L1) gene, named circBCL2L1, which was related to the innate immune responses in teleost fish. Results indicated that circBCL2L1 played essential roles in host antiviral immunity and antibacterial immunity. Our study also identified a microRNA, miR-30c-3-3p, which could inhibit the innate immune response by targeting inflammatory mediator TRAF6. And TRAF6 is a key signal transduction factor in innate immune response mediated by TLRs. Moreover, we also found that the antiviral and antibacterial effects inhibited by miR-30c-3-3p could be reversed with the expression of circBCL2L1. Our data revealed that circBCL2L1 functioned as a competing endogenous RNA (ceRNA) of TRAF6 by competing for binding with miR-30c-3-3p, leading to activation of the NF-κB/IRF3 inflammatory pathway and then enhancing the innate immune responses. Our results suggest that circRNAs can play an important role in the innate immune response of teleost fish.

In silico and gene expression analysis of the acute inflammatory response of gilthead seabream (Sparus aurata) after subcutaneous administration of carrageenin

Inflammation is one of the main causes of loss of homeostasis at both the systemic and molecular levels. The aim of this study was to investigate in silico the conservation of inflammation-related proteins in the gilthead seabream (Sparus aurata L.). Open reading frames of the selected genes were used as input in the STRING database for protein-protein interaction network analysis, comparing them with other teleost protein sequences. Proteins of the large yellow croaker (Larimichthys crocea L.) presented the highest percentages of identity with the gilthead seabream protein sequence. The gene expression profile of these proteins was then studied in gilthead seabream specimens subcutaneously injected with carrageenin (1%) or phosphate-buffered saline (control) by analyzing skin samples from the injected zone 12 and 24 h after injection. Gene expression analysis indicated that the mechanisms necessary to terminate the inflammatory response to carrageenin and recover skin homeostasis were activated between 12 and 24 h after injection (at the tested dose). The gene analysis performed in this study could contribute to the identification of the main mechanisms of acute inflammatory response and validate the use of carrageenin as an inflammation model to elucidate these mechanisms in fish.

Exosomal miR-224 contributes to hemolymph microbiota homeostasis during bacterial infection in crustacean

It is well known that exosomes could serve as anti-microbial immune factors in animals. However, despite growing evidences have shown that the homeostasis of the hemolymph microbiota was vital for immune regulation in crustaceans, the relationship between exosomes and hemolymph microbiota homeostasis during pathogenic bacteria infection has not been addressed. Here, we reported that exosomes released from Vibrio parahaemolyticus-infected mud crabs (Scylla paramamosain) could help to maintain the homeostasis of hemolymph microbiota and have a protective effect on the mortality of the host during the infection process. We further confirmed that miR-224 was densely packaged in these exosomes, resulting in the suppression of HSP70 and disruption of the HSP70-TRAF6 complex, then the released TRAF6 further interacted with Ecsit to regulate the production of mitochondrial ROS (mROS) and the expression of Anti-lipopolysaccharide factors (ALFs) in recipient hemocytes, which eventually affected hemolymph microbiota homeostasis in response to the pathogenic bacteria infection in mud crab. To the best of our knowledge, this is the first document that reports the role of exosome in the hemolymph microbiota homeostasis modulation during pathogen infection, which reveals the crosstalk between exosomal miRNAs and innate immune response in crustaceans.

Exosomes are small membrane vesicles of endocytic origin which are widely involved in the regulation of a variety of pathological processes in mammals. Yet, although the antibacterial function of exosomes has been discovered for many years, the relationship between exosomes and hemolymph microbiota homeostasis remains unknown. In the present study, we identified the miRNAs packaged by exosomes that were possibly involved in Vibrio parahaemolyticus infection by modulating hemolymph microbiota homeostasis in crustacean mud crab Scylla paramamosain. Moreover, it was found that miR-224 was densely packaged in exosomes after Vibrio parahaemolyticus challenge, resulting in the suppression of HSP70 and disruption of the HSP70-TRAF6 complex in recipient hemocytes, then the released TRAF6 was further interacted with Ecsit to regulate ROS and ALFs levels, which eventually affected hemolymph microbiota homeostasis to cope with pathogenic bacteria infection. Our finding is the first to reveal the relationship between exosomes and hemolymph microbiota homeostasis in animals, which shows a novel molecular mechanism of invertebrate resistance to pathogenic microbial infection.

High SPINK4 Expression Predicts Poor Outcomes among Rectal Cancer Patients Receiving CCRT

Background: Patients with rectal cancer can prospectively be favored for neoadjuvant concurrent chemoradiotherapy (CCRT) to downstage before a radical proctectomy, but the risk stratification and clinical outcomes remain disappointing. Methods: From a published rectal cancer transcriptome dataset (GSE35452), we highlighted extracellular matrix (ECM)-linked genes and identified the serine protease inhibitor Kazal-type 4 (SPINK4) gene as the most relevant among the top 10 differentially expressed genes associated with CCRT resistance. We accumulated the cases of 172 rectal cancer patients who received neoadjuvant CCRT followed by surgery and collected tumor specimens for the evaluation of the expression of SPINK4 using immunohistochemistry. Results: The results revealed that high SPINK4 immunoexpression was significantly related to advanced pre-CCRT and post-CCRT tumor status (both p < 0.001), post-CCRT lymph node metastasis (p = 0.001), more vascular and perineurial invasion (p = 0.015 and p = 0.023), and a lower degree of tumor regression (p = 0.001). In univariate analyses, high SPINK4 immunoexpression was remarkably correlated with worse disease-specific survival (DSS) (p < 0.0001), local recurrence-free survival (LRFS) (p = 0.0017), and metastasis-free survival (MeFS) (p < 0.0001). Furthermore, in multivariate analyses, high SPINK4 immunoexpression remained independently prognostic of inferior DSS and MeFS (p = 0.004 and p = 0.002). Conclusion: These results imply that high SPINK4 expression is associated with advanced clinicopathological features and a poor therapeutic response among rectal cancer patients undergoing CCRT, thus validating the prospective prognostic value of SPINK4 for those patients.

Genetic and biological hallmarks of colorectal cancer

Colorectal cancer has served as a genetic and biological paradigm for the evolution of solid tumors, and these insights have illuminated early detection, risk stratification, prevention, and treatment principles. Employing the hallmarks of cancer framework, we provide a conceptual framework to understand how genetic alterations in colorectal cancer drive cancer cell biology properties and shape the heterotypic interactions across cells in the tumor microenvironment. This review details research advances pertaining to the genetics and biology of colorectal cancer, emerging concepts gleaned from immune and single-cell profiling, and critical advances and remaining knowledge gaps influencing the development of effective therapies for this cancer that remains a major public health burden.

Pyridostigmine Protects Against Diabetic Cardiomyopathy by Regulating Vagal Activity, Gut Microbiota, and Branched-Chain Amino Acid Catabolism in Diabetic Mice

The disruption of gut microbes is associated with diabetic cardiomyopathy, but the mechanism by which gut microbes affect cardiac damage remains unclear. We explored gut microbes and branched-chain amino acid (BCAA) metabolite catabolism in diabetic cardiomyopathy mice and investigated the cardioprotective effect of pyridostigmine. The experiments were conducted using a model of diabetic cardiomyopathy induced by a high-fat diet + streptozotocin in C57BL/6 mice. The results of high-throughput sequencing showed that diabetic cardiomyopathy mice exhibited decreased gut microbial diversity, altered abundance of the diabetes-related microbes, and increased abundance of the BCAA-producing microbes Clostridiales and Lachnospiraceae. In addition, diabetes downregulated tight junction proteins (ZO-1, occludin, and claudin-1) and increased intestinal permeability to impair the intestinal barrier. These impairments were accompanied by reduction in vagal activity that manifested as increased acetylcholinesterase levels, decreased acetylcholine levels, and heart rate variability, which eventually led to cardiac damage. Pyridostigmine enhanced vagal activity, restored gut microbiota homeostasis, decreased BCAA-producing microbe abundance, and improved the intestinal barrier to reduce circulating BCAA levels. Pyridostigmine also upregulated BCAT2 and PP2Cm and downregulated p-BCKDHA/BCKDHA and BCKDK to improve cardiac BCAA catabolism. Moreover, pyridostigmine alleviated abnormal mitochondrial structure; increased ATP production; decreased reactive oxygen species and mitochondria-related apoptosis; and attenuated cardiac dysfunction, hypertrophy, and fibrosis in diabetic cardiomyopathy mice. In conclusion, the gut microbiota, BCAA catabolism, and vagal activity were impaired in diabetic cardiomyopathy mice but were improved by pyridostigmine. These results provide novel insights for the development of a therapeutic strategy for diabetes-induced cardiac damage that targets gut microbes and BCAA catabolism.

E3 Ubiquitin Ligase in Anticancer Drugdsla Resistance: Recent Advances and Future Potential

Drug therapy is the primary treatment for patients with advanced cancer. The use of anticancer drugs will inevitably lead to drug resistance, which manifests as tumor recurrence. Overcoming chemoresistance may enable cancer patients to have better therapeutic effects. However, the mechanisms underlying drug resistance are poorly understood. E3 ubiquitin ligases (E3s) are a large class of proteins, and there are over 800 putative functional E3s. E3s play a crucial role in substrate recognition and catalyze the final step of ubiquitin transfer to specific substrate proteins. The diversity of the set of substrates contributes to the diverse functions of E3s, indicating that E3s could be desirable drug targets. The E3s MDM2, FBWX7, and SKP2 have been well studied and have shown a relationship with drug resistance. Strategies targeting E3s to combat drug resistance include interfering with their activators, degrading the E3s themselves and influencing the interaction between E3s and their substrates. Research on E3s has led to the discovery of possible therapeutic methods to overcome the challenging clinical situation imposed by drug resistance. In this article, we summarize the role of E3s in cancer drug resistance from the perspective of drug class.

TRIM37 negatively regulates inflammatory responses induced by virus infection via controlling TRAF6 ubiquitination

Virus-induced cytokine storm has been a devastating actuality in clinic. The abnormal production of type I interferon (IFN-1) and upregulation of multiple cytokines induced strong inflammation and thus lead to shock and organ failure. As an E3 ubiquitin ligase, tripartite motif-containing 37 (TRIM37) regulates the ubiquitination of multiple proteins including TRAFs. RNA sequencing was performed to investigated the alteration of transcriptional profile of H1N1-infected patients. qRT-PCR assay was performed to investigate the RNA levels of certain genes. The group of immune cells was examined by the Flow cytometry analysis. H&E staining was applied to evaluate lung inflammation of WT and TRIM37-KO mice. ELISA assay was performed to demonstrate the alteration of multiple cytokines. The protein levels in NF-kB signaling was estimated by western blotting and immunoprecipitation assays were applied to demonstrate the direct interaction between TRIM37 and TRAF-6. The RNA level of TRIM37 decreased in CD11b⁺ cells of Flu-infected patients. Knockout of TRIM37 inhibited the immune responses of H1N1-infected mice. TRIM37 deficiency reduced the levels of virous proinflammatory cytokines in bone marrow derived macrophages (BMDMs). Mechanically, TRIM37 promoted the K63-linked ubiquitination of TRAF6. TRIM37 negatively regulated inflammatory responses induced by virus infection via promoting TRAF6 ubiquitination at K63.

Characterization of Biological Pathways Regulating Acute Cold Resistance of Zebrafish

Low temperature stress represents a major threat to the lives of both farmed and wild fish species. However, biological pathways determining the development of cold resistance in fish remain largely unknown. Zebrafish larvae at 96 hpf were exposed to lethal cold stress (10 °C) for different time periods to evaluate the adverse effects at organism, tissue and cell levels. Time series RNA sequencing (RNA-seq) experiments were performed to delineate the transcriptomic landscape of zebrafish larvae under cold stress and during the subsequent rewarming phase. The genes regulated by cold stress were characterized by progressively enhanced or decreased expression, whereas the genes associated with rewarming were characterized by rapid upregulation upon return to normal temperature (28 °C). Genes such as trib3, dusp5 and otud1 were identified as the representative molecular markers of cold-induced damages through network analysis. Biological pathways involved in cold stress responses were mined from the transcriptomic data and their functions in regulating cold resistance were validated using specific inhibitors. The autophagy, FoxO and MAPK (mitogen-activated protein kinase) signaling pathways were revealed to be survival pathways for enhancing cold resistance, while apoptosis and necroptosis were the death pathways responsible for cold-induced mortality. Functional mechanisms of the survival-enhancing factors Foxo1, ERK (extracellular signal-regulated kinase) and p38 MAPK were further characterized by inhibiting their activities upon cold stress and analyzing gene expression though RNA-seq. These factors were demonstrated to determine the cold resistance of zebrafish through regulating apoptosis and p53 signaling pathway. These findings have provided novel insights into the stress responses elicited by lethal cold and shed new light on the molecular mechanisms underlying cold resistance of fish.

TRIM Proteins in Colorectal Cancer: TRIM8 as a Promising Therapeutic Target in Chemo Resistance

Colorectal cancer (CRC) represents one of the most widespread forms of cancer in the population and, as all malignant tumors, often develops resistance to chemotherapies with consequent tumor growth and spreading leading to the patient’s premature death. For this reason, a great challenge is to identify new therapeutic targets, able to restore the drugs sensitivity of cancer cells. In this review, we discuss the role of TRIpartite Motifs (TRIM) proteins in cancers and in CRC chemoresistance, focusing on the tumor-suppressor role of TRIM8 protein in the reactivation of the CRC cells sensitivity to drugs currently used in the clinical practice. Since the restoration of TRIM8 protein levels in CRC cells recovers chemotherapy response, it may represent a new promising therapeutic target in the treatment of CRC.

Regulation of p53 stability as a therapeutic strategy for cancer

The tumor suppressor protein p53 participates in the control of key biological functions such as cell death, metabolic homeostasis and immune function, which are closely related to various diseases such as tumors, metabolic disorders, infection and neurodegeneration. The p53 gene is also mutated in approximately 50% of human cancer cells. Mutant p53 proteins escape from the ubiquitination-dependent degradation, gain oncogenic function and promote the carcinogenesis, malignant progression, metastasis and chemoresistance. Therefore, the stability of both wild type and mutant p53 needs to be precisely regulated to maintain normal functions and targeting the p53 stability is one of the therapeutic strategies against cancer. Here, we focus on compound-induced degradation of p53 by both the ubiquitination-dependent proteasome and autophagy-lysosome degradation pathways. We also review other posttranslational modifications which control the stability of p53 and the biological functions involved in these processes. This review provides the current theoretical basis for the regulation of p53 abundance and its possible applications in different diseases.

Investigating Conformational Dynamics and Allostery in the p53 DNA-Binding Domain Using Molecular Simulations

The p53 tumor suppressor is a multifaceted context-dependent protein, which is involved in multiple cellular pathways, with the ability to either keep the cells alive or to kill them through mechanisms such as apoptosis. To complicate this picture, cancer cells that express mutant p53 becomes addicted to the mutant activity, so that the mutant variant features a myriad of gain-of-function activities, opening different venues for therapy. This makes essential to think outside the box and apply new approaches to the study of p53 structure-(mis)function relationship to find new critical components of its pathway or to understand how known parts are interconnected, compete, or cooperate. In this context, I will here illustrate how to integrate different computational methods to the identification of possible allosteric effects transmitted from the DNA binding interface of p53 to regions for cofactor recruitment. The protocol can be extended to any other cases of study. Indeed, it does not necessarily apply only to the study of DNA-induced effects, but more broadly to the investigation of long-range effects induced by a biological partner that binds to a biomolecule of interest.

TNF-Receptor-Associated Factor 3 in Litopenaeus vannamei Restricts White Spot Syndrome Virus Infection Through the IRF-Vago Antiviral Pathway

Tumor necrosis factor receptor (TNFR)-associated factors (TRAFs) are vital signaling adaptor proteins for the innate immune response and are involved in many important pathways, such as the NF-κB- and interferon regulatory factor (IRF)-activated signaling pathways. In this study, the TRAF3 ortholog from the shrimp Litopenaeus vannamei (LvTRAF3) was cloned and characterized. LvTRAF3 has a transcript of 3,865 bp, with an open reading frame (ORF) of 1,002 bp and encodes a polypeptide of 333 amino acids, including a conserved TRAF-C domain. The expression of LvTRAF3 in the intestine and hemocyte was up-regulated in response to poly (I:C) challenge and white spot syndrome virus (WSSV) infection. RNAi knockdown of LvTRAF3 in vivo significantly increased WSSV gene transcription, viral loads, and mortality in WSSV-infected shrimp. Next, we found that LvTRAF3 was not able to induce the activation of the NF-κB pathway, which was crucial for synthesis of antimicrobial peptides (AMPs), which mediate antiviral immunity. Specifically, in dual-luciferase reporter assays, LvTRAF3 could not activate several types of promoters with NF-κB binding sites, including those from WSSV genes (wsv069, wsv056, and wsv403), Drosophila AMPs or shrimp AMPs. Accordingly, the mRNA levels of shrimp AMPs did not significantly change when TRAF3 was knocked down during WSSV infection. Instead, we found that LvTRAF3 signaled through the IRF-Vago antiviral cascade. LvTRAF3 functioned upstream of LvIRF to regulate the expression of LvVago4 and LvVago5 during WSSV infection in vivo. Taken together, these data provide experimental evidence of the participation of LvTRAF3 in the host defense to WSSV through the activation of the IRF-Vago pathway but not the NF-κB pathway.

Mitochondrial MicroRNAs in Aging and Neurodegenerative Diseases

MicroRNAs (miRNAs) are important regulators of several biological processes, such as cell growth, cell proliferation, embryonic development, tissue differentiation, and apoptosis. Currently, over 2000 mammalian miRNAs have been reported to regulate these biological processes. A subset of microRNAs was found to be localized to human mitochondria (mitomiRs). Through years of research, over 400 mitomiRs have been shown to modulate the translational activity of the mitochondrial genome. While miRNAs have been studied for years, the function of mitomiRs and their role in neurodegenerative pathologies is not known. The purpose of our article is to highlight recent findings that relate mitomiRs to neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and Huntington’s. We also discuss the involvement of mitomiRs in regulating the mitochondrial genome in age-related neurodegenerative diseases.

F-Box Proteins and Cancer

Controlled protein degradation is essential for the operation of a variety of cellular processes including cell division, growth, and differentiation. Identification of the relations between ubiquitin ligases and their substrates is key to understanding the molecular basis of cancer development and to the discovery of novel targets for cancer therapeutics. F-box proteins function as the substrate recognition subunits of S-phase kinase-associated protein 1 (SKP1)−Cullin1 (CUL1)−F-box protein (SCF) ubiquitin ligase complexes. Here, we summarize the roles of specific F-box proteins that have been shown to function as tumor promoters or suppressors. We also highlight proto-oncoproteins that are targeted for ubiquitylation by multiple F-box proteins, and discuss how these F-box proteins are deployed to regulate their cognate substrates in various situations.

TRAF6 suppresses the apoptosis of hemocytes by activating pellino in Crassostrea hongkongensis

Tumor necrosis factor receptor-associated factor 6 (TRAF6), an E3 ubiquitin ligase, participates in both innate and adaptive immunity and regulates the apoptotic process. In this study, we observed that an ortholog of TRAF6 could inhibit the activity of p53 and suppress the apoptotic process in the Hong Kong oyster, Crassostrea hongkongensis. To investigate the possible molecular mechanism of the ChTRAF6-induced antiapoptotic effect, a GST pull-down screening assay was conducted, and ChPellino was found to physically interact with ChTRAF6. In addition, the interaction between them was confirmed by Co-immunoprecipitation. Furthermore, western blotting revealed that the phosphorylation level of ChPellino was decreased after the RNAi of ChTRAF6, demonstrating that ChTRAF6 may be an upstream regulator of Pellino activation. Furthermore, the apoptosis level of hemocytes increased after ChPellino knockdown, and ChPellino overexpression suppressed ChTRAF6-dependent p53 activation. Taken together, these results indicate that ChPellino plays a critical role in suppressing ChTRAF6-dependent anti-apoptosis in the hemocytes of Crassostrea hongkongensis.

Chromosome arm aneuploidies shape tumour evolution and drug response

Chromosome arm aneuploidies (CAAs) are pervasive in cancers. However, how they affect cancer development, prognosis and treatment remains largely unknown. Here, we analyse CAA profiles of 23,427 tumours, identifying aspects of tumour evolution including probable orders in which CAAs occur and CAAs predicting tissue-specific metastasis. Both haematological and solid cancers initially gain chromosome arms, while only solid cancers subsequently preferentially lose multiple arms. 72 CAAs and 88 synergistically co-occurring CAA pairs multivariately predict good or poor survival for 58% of 6977 patients, with negligible impact of whole-genome doubling. Additionally, machine learning identifies 31 CAAs that robustly alter response to 56 chemotherapeutic drugs across cell lines representing 17 cancer types. We also uncover 1024 potential synthetic lethal pharmacogenomic interactions. Notably, in predicting drug response, CAAs substantially outperform  mutations and focal deletions/amplifications combined. Thus, CAAs predict cancer prognosis, shape tumour evolution, metastasis and drug response, and may advance precision oncology.

Long noncoding RNA LINC01234 promoted cell proliferation and invasion via miR-1284/TRAF6 axis in colorectal cancer

Colorectal cancer is one of the most common and leading malignancies globally. Long noncoding RNAs (lncRNAs) function as potentially critical regulator in colorectal cancer. LINC01234, a novel lncRNA in tumor biology, regulates the progression of various tumors. However, the tumorigenic mechanism of LINC01234 in colorectal cancer is still unclear. This study was performed with the aim to prospectively investigate clinical significance, effect, and mechanism of lncRNA LINC01234 in colorectal cancer. First, we found that LINC01234, localized in the cytoplasm, was increased in both colorectal cancer cell lines and tissues. Subsequent functional assays suggested LINC01234 knockdown suppressed cell proliferation, migration, and invasion of colorectal cancer cells, while blocked cell cycle and induced cell apoptosis. Moreover, we identified that miR-1284 was target of LINC01234, we further demonstrated a negative correlation with LINC01234 in colorectal cancer tissues and cells. Furthermore, miR-1284 targeted and suppressed tumor necrosis factor receptor-associated factor 6 (TRAF6). Loss-of-function assay revealed that LINC01234 silencing suppressed colorectal cancer progression through inhibition of miR-1284. In vivo subcutaneous xenotransplanted tumor model indicated LINC01234 knockdown inhibited in vivo tumorigenic ability of colorectal cancer via downregulation of TRAF6. Collectively, this study clarified the biological significance of LINC01234/miR-1284/TRAF6 axis in colorectal cancer progression, providing insights into LINC01234 as novel potential therapeutic target for colorectal cancer therapeutic from bench to clinic.

Pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice

Diabetic patients are more susceptible to myocardial ischemia damage than nondiabetic patients, with worse clinical outcomes and greater mortality. The mechanism may be related to glucose metabolism, mitochondrial homeostasis, and oxidative stress. Pyridostigmine may improve vagal activity to protect cardiac function in cardiovascular diseases. Researchers have not determined whether pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice. In the present study, autonomic imbalance, myocardial damage, mitochondrial dysfunction, and oxidative stress were exacerbated in isoproterenol-stimulated diabetic mice, revealing the myocardial vulnerability of diabetic mice to injury compared with mice with diabetes or exposed to isoproterenol alone. Compared with normal mice, the expression of glucose transporters (GLUT)1/4 phosphofructokinase (PFK) FB3, and pyruvate kinase isoform (PKM) was decreased in diabetic mice, but increased in isoproterenol-stimulated normal mice. Following exposure to isoproterenol, the expression of (GLUT)1/4 phosphofructokinase (PFK) FB3, and PKM decreased in diabetic mice compared with normal mice. The downregulation of SIRT3/AMPK and IRS-1/Akt in isoproterenol-stimulated diabetic mice was exacerbated compared with that in diabetic mice or isoproterenol-stimulated normal mice. Pyridostigmine improved vagus activity, increased GLUT1/4, PFKFB3, and PKM expression, and ameliorated mitochondrial dysfunction and oxidative stress to reduce myocardial damage in isoproterenol-stimulated diabetic mice. Based on these results, it was found that pyridostigmine may reduce myocardial vulnerability to injury via the SIRT3/AMPK and IRS-1/Akt pathways in diabetic mice with isoproterenol-induced myocardial damage. This study may provide a potential therapeutic target for myocardial damage in diabetic patients.

TRAF6 Mediates Basal Activation of NF-κB Necessary for Hematopoietic Stem Cell Homeostasis

Basal nuclear factor κB (NF-κB) activation is required for hematopoietic stem cell (HSC) homeostasis in the absence of inflammation; however, the upstream mediators of basal NF-κB signaling are less well understood. Here, we describe TRAF6 as an essential regulator of HSC homeostasis through basal activation of NF-κB. Hematopoietic-specific deletion of Traf6 resulted in impaired HSC self-renewal and fitness. Gene expression, RNA splicing, and molecular analyses of Traf6-deficient hematopoietic stem/progenitor cells (HSPCs) revealed changes in adaptive immune signaling, innate immune signaling, and NF-κB signaling, indicating that signaling via TRAF6 in the absence of cytokine stimulation and/or infection is required for HSC function. In addition, we established that loss of IκB kinase beta (IKKβ)-mediated NF-κB activation is responsible for the major hematopoietic defects observed in Traf6-deficient HSPC as deletion of IKKβ similarly resulted in impaired HSC self-renewal and fitness. Taken together, TRAF6 is required for HSC homeostasis by maintaining a minimal threshold level of IKKβ/NF-κB signaling.

Polo-Like Kinase 1 phosphorylates and stabilizes KLF4 to promote tumorigenesis in nasopharyngeal carcinoma

Rationale: Advanced nasopharyngeal carcinoma (NPC) is an aggressive disease with no targeted therapies and poor outcomes. New innovative targets are urgently needed. KLF4 has been extensively studied in the context of tumors, and current data suggest that it can act as either a tissue-specific tumor-inhibiting or a tumor-promoting gene. Here, we found that KLF4 played as a tumor-promoting gene in NPC, and could be mediated by PLK1. Methods: Tissue immunohistochemistry (IHC) assay was performed to identify the role of KLF4 in NPC. Global gene expression experiments were performed to explore the molecular mechanisms underlying KLF4-dependent tumorigenesis. Small-molecule kinase inhibitor screening was performed to identify potential upstream kinases of KLF4. The pharmacologic activity of polo-like kinase inhibitor volasertib (BI6727) in vitro and in vivo was determined. Result: Our investigation showed that high expression of KLF4 was correlated with poor prognosis in NPC. Moreover, genome-wide profiling revealed that KLF4 directly activated oncogenic programmes, including gene sets associated with KRAS, VEGF, and MYC signalling. We further found that inhibition of polo-like kinase 1 could downregulate the expression of KLF4 and that PLK1 directly phosphorylated KLF4 at Ser234. Notably, phosphorylation of KLF4 by PLK1 caused the recruitment and binding of the E3 ligase TRAF6, which resulted in KLF4 K32 K63-linked ubiquitination and stabilization. Moreover, KLF4 could enhance TRAF6 expression at the transcriptional level, thus initiating a KLF4-TRAF6 feed-forward loop. Treatment with the PLK1 inhibitor volasertib (BI6727) significantly inhibited tumor growth in nude mice. Conclusion: Our study unveiled a new PLK1-TRAF6-KLF4 feed-forward loop. The resulting increase in KLF4 ubiquitination leads to stabilization and upregulation of KLF4, which leads to tumorigenesis in NPC. These results expand our understanding of the role of KLF4 in NPC and validate PLK1 inhibitors as potential therapeutic agents for NPC, especially cancer patients with KLF4 overexpression.

Two novel serine proteases from Scylla paramamosain involved in the synthesis of anti-lipopolysaccharide factors and activation of prophenoloxidase system

Serine proteases (SPs) are important in various immune responses, including prophenoloxidase (proPO) activation, antimicrobial peptides (AMPs) synthesis, and hemolymph coagulation in invertebrates. In this study, SP3 and SP5 of mud crab (Scylla paramamosain) were studied. SP3 and SP5 were expressed in all examined tissues (mainly in hemocytes), and are associated with the immune responses of mud crab to Vibrio parahemolyticus and Staphylococcus aureus, as well as interacted with TRAF6, and are involved in the activation of anti-lipopolysaccharide factors (ALFs) probably through the TLR/NF-κB pathway. Depletion of SP3 inhibited the expression of ALF1, ALF2, ALF3, and ALF6, while knockdown of SP5 significantly decreased ALF5, and ALF6. Furthermore, both SP5 and TRAF6 regulated the PO activity in the hemolymph of mud crab. Overexpression assay showed that both SP3 and SP5 could enhance the promoter activities of ALFs in mud crab. Taken together, the results of this study indicate that SP3 and SP5 might play important roles in the immune system of mud crab against pathogen invasion.

Prevention of Wogonin on Colorectal Cancer Tumorigenesis by Regulating p53 Nuclear Translocation

The tumor suppressor protein p53 plays an important role in the development and progression of colon cancer, and the subcellular organelle localization directly affects its function. Wogonin (5,7-dihydroxy-8-methoxyflavone), a mono-flavonoid extracted from root of Scutellaria baicalensis Georgi, possesses acceptable toxicity and has been used in colorectal cancer (CRC) chemoprevention in pre-clinical trials by oncologist. However, the underlying anti-colon cancer mechanisms of wogonin are not yet fully understood. In the present study, the effect of wogonin on the initiation and development of colitis-associated cancer through p53 nuclear translocation was explored. AOM-DSS CRC animal model and human CRC HCT-116 cell model were used to evaluate the in vivo and in vitro anti-colon cancer action of wogonin. We observed that wogonin showed a dramaticlly preventive effect on colon cancer. Our results showed that wogonin caused apoptotic cell death in human CRC HCT-116 cell through increased endoplasmic reticulum (ER) stress. Meanwhile, excessive ER stress facilitated the cytoplasmic localization of p53 through increasing phosphor-p53 at S315 and S376 sites, induced caspase-dependent apoptosis and inhibited autophagy. Furthermore, we verified the chemoprevention effect and toxicity of wogonin in vivo by utilizing an AOM-DSS colon cancer animal model. We found that wogonin not only reduced tumor multiplicity, preserved colon length to normal (6.79 ± 0.34 to 7.41 ± 0.56, P < 0.05) but also didn’t induce side effects on various organs. In conclusion, these results explain the anti-tumor effect of wogonin in CRC and suggest wogonin as a potential therapeutic candidate for the therapeutic strategy in CRC treatment.

Genetic Alterations of TRAF Proteins in Human Cancers

The tumor necrosis factor receptor (TNF-R)-associated factor (TRAF) family of cytoplasmic adaptor proteins regulate the signal transduction pathways of a variety of receptors, including the TNF-R superfamily, Toll-like receptors (TLRs), NOD-like receptors (NLRs), RIG-I-like receptors (RLRs), and cytokine receptors. TRAF-dependent signaling pathways participate in a diverse array of important cellular processes, including the survival, proliferation, differentiation, and activation of different cell types. Many of these TRAF-dependent signaling pathways have been implicated in cancer pathogenesis. Here we analyze the current evidence of genetic alterations of TRAF molecules available from The Cancer Genome Atlas (TCGA) and the Catalog of Somatic Mutations in Cancer (COSMIC) as well as the published literature, including copy number variations and mutation landscape of TRAFs in various human cancers. Such analyses reveal that both gain- and loss-of-function genetic alterations of different TRAF proteins are commonly present in a number of human cancers. These include pancreatic cancer, meningioma, breast cancer, prostate cancer, lung cancer, liver cancer, head and neck cancer, stomach cancer, colon cancer, bladder cancer, uterine cancer, melanoma, sarcoma, and B cell malignancies, among others. Furthermore, we summarize the key in vivo and in vitro evidence that demonstrates the causal roles of genetic alterations of TRAF proteins in tumorigenesis within different cell types and organs. Taken together, the information presented in this review provides a rationale for the development of therapeutic strategies to manipulate TRAF proteins or TRAF-dependent signaling pathways in different human cancers by precision medicine.

STX2 promotes colorectal cancer metastasis through a positive feedback loop that activates the NF-κB pathway

Metastatic progression is the main contributor to the poor prognosis of colorectal cancer (CRC). Thus, identifying the determinants of CRC metastasis will be of great significance. Based on our previous bioinformatics analysis, Syntaxin2 (STX2) may be upregulated and correlated with the poor prognosis of CRC patients. In this study, we found that STX2 expression was associated with CRC invasion and metastasis and poor patient survival. Gain- and loss-of-function analyses demonstrated that STX2 functioned as a key oncogene by promoting CRC invasion and metastasis. Mechanistically, STX2 selectively interacted with tumor necrosis factor receptor-associated factor 6 (TRAF6) and activated the nuclear transcription factor-κB (NF-κB) signaling pathway. Furthermore, chromatin immunoprecipitation (ChIP) analysis revealed that NF-κB directly bound to the STX2 promoter and drove STX2 transcription. Therefore, STX2 activated the NF-κB pathway, and in turn, NF-κB increased STX2 expression, forming a positive signaling loop that eventually promoted CRC metastasis. Collectively, our results reveal STX2 as a crucial modulator of the aggressive CRC phenotype and highlight STX2 as a potential prognostic biomarker and therapeutic target for combating CRC metastasis.

Loss of P53 regresses cardiac remodeling induced by pressure overload partially through inhibiting HIF1α signaling in mice

The tumor suppressor p53 is recognized as the guardian of the genome in cell cycle and cell death. P53 expression increases as cardiac hypertrophy worsens to heart failure, suggesting that p53 may play important role in cardiac remodeling. In the present study, deletion of p53 in the mice heart would ameliorate cardiac hypertrophy induced by pressure overload. The role of p53 on heart was investigated using in vivo models. Cardiac hypertrophy in mice was induced by transverse aortic banding surgery. The extent of cardiac hypertrophy was examined by echocardiography, as well as pathological and molecular analyses of heart tissue. Global knockout of p53 in the mice reduced the hypertrophic response and markedly reduced cardiac apoptosis, and fibrosis. Ejection fraction of heart was also improved in hearts without p53 in response to pressure overload. Protein determination further suggested loss of p53 expression markedly increased Hypoxia-inducible factor 1-alpha (HIF1α) and vascular endothelial growth factor (VEGF) expression. The study indicated p53 deteriorated cardiac functions and cardiac hypertrophy, apoptosis, and fibrosis by partially inhibition of HIF1α and VEGF.

Metabolic reprogramming of the tumor microenvironment by p62 and its partners

The concerted metabolic reprogramming across cancer and normal cellular compartments of the tumor microenvironment can favor tumorigenesis by increasing the survival and proliferating capacities of transformed cells. p62 has emerged as a critical signaling adaptor, beyond its role in autophagy, by playing an intricate context-dependent role in metabolic reprogramming of the cell types of the tumor and stroma, which shapes the tumor microenvironment to control tumor progression. Focusing on metabolic adaptations, we review the cellular processes upstream and downstream of p62 that regulate how distinct cell types adapt to the challenging and evolving environmental conditions during tumor initiation and progression. In addition, we describe partners of p62 that, in a collaborative or independent manner, can also rewire cell metabolism. Finally, we discuss the potential therapeutic implications of targeting p62 in cancer, considering its multifaceted roles in diverse cell types of the tumor microenvironment.