Research progress of Parkin protein regulating mitochondrial homeostasis through ubiquitination in cardiovascular diseases / 中国药理学通报

In addition to providing energy for cells, mitochondria also participate in calcium homeostasis, cell information transfer, cell apoptosis, cell growth and differentiation. Therefore, maintaining mitochondrial homeostasis is very crucial for the body to carry out normal life activities. Ubiquitination, a post-translational modification of proteins, is involved in various physiological and pathological processes of cells by regulating mitochondrial homeostasis. However, the mechanism by which ubiquitination regulates mitochondrial homeostasis has not been summarized, especially the effect of Parkin protein on cardiovascular diseases. In this paper, the specific mechanism of mitochondrial homeostasis regulated by ubiquitination of Parkin protein is discussed, and the influence of mitochondrial homeostasis imbalance on cardiovascular diseases is reviewed, with a view to providing potential therapeutic strategies for the clinical treatment of cardiovascular diseases.

Research progress in ferroptosis pathways and ubiquitination modification of ferroptosis-related molecules / 中国药理学通报

Ferroptosis is an iron-dependent cell death caused by phospholipid peroxidation damage of polyunsaturated fatty acids on cell membranes and involves several pathways, including the iron homeostasis regulatory pathway, the cystine glutamate reverse transporter (system Xc) pathway and the voltage-dependent anion channel (VDAC) pathway. Ferroptosis is involved in the development of several diseases (e. g. myocardial infarction, stroke, cancer and degenerative diseases). The ubiquitination is an important post-translational modification of various protein molecules in the organism. Studies have shown that regulating the ubiquitination of ferroptosis pathway-related molecules can control cellular ferroptosis. Targeting the ubiquitination of ferroptosis pathway-related molecules can effectively promote or inhibit ferroptosis, which is expected to be a new strategy for the treatment of cancer or cardiovascular diseases. In this paper we review the progress of the ferroptosis pathways and the ubiquitination modification of ferroptosis-related molecules.

GLUL stabilizes N-Cadherin by antagonizing β-Catenin to inhibit the progresses of gastric cancer

Glutamate-ammonia ligase (GLUL, also known as glutamine synthetase) is a crucial enzyme that catalyzes ammonium and glutamate into glutamine in the ATP-dependent condensation. Although GLUL plays a critical role in multiple cancers, the expression and function of GLUL in gastric cancer remain unclear. In the present study, we have found that the expression level of GLUL was significantly lower in gastric cancer tissues compared with adjacent normal tissues, and correlated with N stage and TNM stage, and low GLUL expression predicted poor survival for gastric cancer patients. Knockdown of GLUL promoted the growth, migration, invasion and metastasis of gastric cancer cells in vitro and in vivo, and vice versa, which was independent of its enzyme activity. Mechanistically, GLUL competed with β-Catenin to bind to N-Cadherin, increased the stability of N-Cadherin and decreased the stability of β-Catenin by alerting their ubiquitination. Furthermore, there were lower N-Cadherin and higher β-Catenin expression levels in gastric cancer tissues compared with adjacent normal tissues. GLUL protein expression was correlated with that of N-Cadherin, and could be the independent prognostic factor in gastric cancer. Our findings reveal that GLUL stabilizes N-Cadherin by antagonizing β-Catenin to inhibit the progress of gastric cancer.

Advances on BTB protein ubiquitination mediated plant development and stress response / 生物工程学报

The BTB (broad-complex, tramtrack, and bric-à-brac) domain is a highly conserved protein interaction motif in eukaryotes. They are widely involved in transcriptional regulation, protein degradation and other processes. Recently, an increasing number of studies have shown that these genes play important roles in plant growth and development, biotic and abiotic stress processes. Here, we summarize the advances of these proteins ubiquitination-mediated development and abiotic stress responses in plants based on the protein structure, which may facilitate the study of this type of gene in plants.

Role of post-translational modification of basic leucine zipper transcription factors in response to abiotic stresses in plants / 生物工程学报

Abiotic stresses substantially affect the growth and development of plants. Plants have evolved multiple strategies to cope with the environmental stresses, among which transcription factors play an important role in regulating the tolerance to abiotic stresses. Basic leucine zipper transcription factors (bZIP) are one of the largest gene families. The stability and activity of bZIP transcription factors could be regulated by different post-translational modifications (PTMs) in response to various intracellular or extracellular stresses. This paper introduces the structural feature and classification of bZIP transcription factors, followed by summarizing the PTMs of bZIP transcription factors, such as phosphorylation, ubiquitination and small ubiquitin-like modifier (SUMO) modification, in response to abiotic stresses. In addition, future perspectives were prospected, which may facilitate cultivating excellent stress-resistant crop varieties by regulating the PTMs of bZIP transcription factors.

Effect of icariin on ubiquitination of amyloid precur-sor protein in Alzheimer's disease mice / 中国药理学与毒理学杂志

OBJECTIVE To investigate the effect of icariin(ICA)on the ubiquitination modification of β-amy-loid precursor protein(APP)in Alzheimer's disease mice.METHODS In vitro,① HEK 293 cells stably overex-pressing human APP695(OE-hAPP)were treated with different concentrations of ICA(10-100 μmol·L-1)for 24 h and the cell viability was detected by MTT assay.②CHX(50 mg·L-1)was used to block protein synthesis and MG132(20 μmol·L-1)inhibits proteasome activity,then the level of APP in different time(0,0.5,1,2,3 and 4 h)and the ubiquitination were tested by Western blotting.③ E3 ubiquitin ligases HMG-CoA reductase degradation pro-tein 1(HRD1)protein expression in OE-hAPP was tested by Western blotting,as well as the level and ubiquitination of APP were tested under HRD1 silent condition by Co-IP and Western blotting.In vivo,① male APP/PS1 mice and wild type(WT)mice were randomly divided into 5 groups:WT,WT+ICA,APP/PS1,APP/PS1+ICA,and APP/PS1+donepezil(DPZ)groups.ICA(60 mg·kg-1·d-1)and DPZ(1 mg·kg-1·d-1)were treated for 3 months by gavage from 6 months of age,and WT mice were given equal volume of distilled water.②Morris water maze and Y-maze experiments were used to detect the alteration of spatial learning memory function.③ After then,the brain tissues were collected,total proteins were extracted,APP antibodies were subjected to Co-IP,and total ubiqui-tination(Ub),K48-linked polyubiquitination(UbK48)and K63-linked polyubiquitination of APP level,APP and HRD1 proteins were detected by Western blotting.RESULTS In vitro results showed that ICA significantly enhanced APP degradation(vs control,P＜0.01),up-reg-ulated HRD1 expression(vs control,P＜0.05;vs OE-hAPP,P＜0.05),elevated the level Ub and UbK48 of APP,as well as increased APP degradation.Moreover,silenced HRD1 gene abolished abovementioned effects of ICA(vs control-siRNA,P＜0.05;vs HRD1-siRNA,P＜0.05).In vivo results showed that ICA improved the spa-tial learning and memory function APP/PS1 mice by Mor-ris water maze and Y-maze tests,increased HRD1 expres-sion(vs APP/PS1 + vehicle,P＜0.05),enhanced APP ubiquitination and reduced APP protein level(vs APP/PS1 + vehicle,P＜0.01).CONCLUSION ICA promotes the ubiquitination and proteasome-dependent degrada-tion of APP by up-regulating HRD1,thereby improving the spatial learning and memory function of Alzheimer disease mice.

Research progress on linear ubiquitin chain assembly complex and OTU deubiquitinase with linear linkage specificity in tumor / 药学实践杂志

Linear ubiquitination is an important post-translational modification that has been discovered in recent years. The linear ubiquitin chain is formed by the linkage of glycine residue of one ubiquitin protein to the methionine residue of another ubiquitin. This process is regulated by the linear ubiquitin chain assembly complex (LUBAC) and the OTU deubiquitinase with linear linkage specificity (OTULIN). Linear ubiquitination is involved in various biological processes, including immune response, inflammation, and cell apoptosis. Recent studies have shown that linear ubiquitination is closely related to the occurrence, development, and drug resistance of tumors by affecting signaling pathways such as NF-κB and Wnt/β-catenin. The research progress on the function of LUBAC and OTULIN in tumors was reviewed in this paper.

The Ubiquitin Ligase SMURF1 Catalyzes the Polyubiquitination of ADAR1 / 中国生物化学与分子生物学报

It is known that SMAD specific E3 ubiquitin protein ligase 1 (SMURF1) mediates autophagy through its E3 ubiquitin ligase activity, but the ubiquitinated substrates of SMURF1 need to be further explored. In this paper, the interacting proteins of SMURF1 in THP-1 cells were captured and identified by co-immunoprecipitation (Co-IP) combined with mass spectrometry. It was found that SMURF1 could physically bind to 222 proteins in THP-1 cells, and Adenosine deaminase acting on RNA 1 (ADAR1) had a higher peptide binding score. SMURF1 overexpression vectors were constructed and transfected into HEK-293T cells, then Co-IP and Western blotting assays verified the interaction between exogenous SMURF1 and endogenous ADAR1. qRT-PCR and Western blotting assays were carried out after transfecting SMURF1 overexpression vectors in HEK-293T cells, which identified that overexpression of SMURF1 attenuated the protein levels of ADAR1 (P<0. 05). However, there was no significant difference in the mRNA level of ADAR1. HEK-293T cells with normal and overexpressing SMURF1 were treated with cycloheximide (CHX), respectively, and Western blotting assays showed a shortened half-life of ADAR1 after overexpression of SMURF1 (P < 0. 05). Furthermore, overexpression of SMURF1 increased the polyubiquitination level of ADAR1 as detected by Co-IP and Western blot (P<0. 05). After the proteasome inhibitor (MG132) treatment, the Western blotting assay was performed to demonstrate that the negative regulatory effect of SMURF1 on ADAR1 was weakened after the proteasome degradation pathway was attenuated (P<0. 05). This study shows that SMURF1 interacts with ADAR1, catalyzes the polyubiquitination of ADAR1 and mediates its degradation through the proteasome pathway, which provides a theoretical basis for exploring the various biological functions of SMURF1 by affecting the stability of ADAR1.

The Role of Post-Translational Modifications of Cav3. 2 in Neuropathic Pain / 中国生物化学与分子生物学报

Neuropathic pain is a common chronic pain that affects human health worldwide. As an important mediator of excitatory conduction in neurons, ion channels are important targets for mechanism research and drug research in this field. T-type calcium channel(Cav3) can be activated transiently when neurons are close to the resting potential of -70 mV, resulting in a transient Ca

Recent developments on transition of lung myofibroblasts / 中国药理学通报

Lung myofibroblasts are important effector that drive the development of idiopathic pulmonary fibrosis, but the mechanisms of lung myofibroblasts transition have not been clarified yet. In this review, we summarize the progress on the mechanisms of lung myofibroblast transitionfrom the aspects of mechanical transduction, metabolism, oxidative stress, ubiquitination and cell senescence in the past five years.

Mechanism of cucurbitacin B suppresses proliferation of hepatocellular carcinoma Huh-7 cells via inducing ferroptosis / 中国药理学通报

Aim To study the effects of cucurbitacin B (Cu B) on proliferation of hepatocellular carcinoma Huh-7 cells and its mechanism. Methods CCK-8 was used to detect the survival rate of Huh-7 cells with different concentrations of Cu B. Huh-7 cells were treated with Cu B (0. 5, 1, 2 njnol; L

Mechanism of nitidine chloride inducing apoptosis of cervical cancer cells by inhibiting p53 ubiquitination degradation / 中国药理学通报

Aim To investigate the effect of nitidine chloride (NC) on the apoptosis of cervical cancer cells and its mechanism. Methods Cervical cancer cell lines HeLa and SiHa were selected as subjects. The cytotoxicity of NC and its inhibitory effect on cell growth were detected by CCK-8 assay and clone formation assay. The effect of NC on the apoptosis of cervical cancer cells was detected by TUNEL assay, and the expression of apoptosis-related proteins was detected by Western blot. The effects of NC on the interaction between p53 and E6AP protein, the level of p53 ubiquitination modification and the stability of p53 protein in cervical cancer cells were analyzed by immunoprecipi-tation assay, ubiquitination assay and Western blot assay. Results NC could significantly inhibit the proliferation and induce apoptosis of cervical cancer cells. NC could inhibit the interaction between tumor suppressor protein p53 and E6AP in cervical cancer cells, reduce the level of p53 ubiquitination modification, delay the degradation of p53 and increase the expression level of p53 protein. Conclusions NC can inhibit the ubiquitination and degradation of p53, improve the expression level of p53 protein, restore its tumor suppressor function, and thus play an anti -cervical cancer role.

Protein phosphorylation involved in psychedelic-induced head-twitch response in rats / 中国药理学通报

Aim To investigate the potential protein post-translational modifications of psychedelic-induced Head-twith response and underling mechanism. Methods Psychedelics LSD, DOM, or Psilocin was administered to rats by intraperitoneal injection to induce head-twitch response, then the most effective dosage was identified to create animal models of head-twitch behavior. Western blot was performed in detecting the protein phosphorylation, acetylation, and ubiquitination in prefrontal cortex of SD rats after 10 min or 30 min injection. Results LSD (0.025 mg • kg~, i. p.), DOM (3 mg•kg

Macrophage LMO7 deficiency facilitates inflammatory injury via metabolic-epigenetic reprogramming

Inflammatory bowel disease (IBD) is a formidable disease due to its complex pathogenesis. Macrophages, as a major immune cell population in IBD, are crucial for gut homeostasis. However, it is still unveiled how macrophages modulate IBD. Here, we found that LIM domain only 7 (LMO7) was downregulated in pro-inflammatory macrophages, and that LMO7 directly degraded 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) through K48-mediated ubiquitination in macrophages. As an enzyme that regulates glycolysis, PFKFB3 degradation led to the glycolytic process inhibition in macrophages, which in turn inhibited macrophage activation and ultimately attenuated murine colitis. Moreover, we demonstrated that PFKFB3 was required for histone demethylase Jumonji domain-containing protein 3 (JMJD3) expression, thereby inhibiting the protein level of trimethylation of histone H3 on lysine 27 (H3K27me3). Overall, our results indicated the LMO7/PFKFB3/JMJD3 axis is essential for modulating macrophage function and IBD pathogenesis. Targeting LMO7 or macrophage metabolism could potentially be an effective strategy for treating inflammatory diseases.

The F-box-only protein 44 regulates pregnane X receptor protein level by ubiquitination and degradation

Pregnane X receptor (PXR) is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes [e.g., cytochrome P450 3A4 (CYP3A4)] and transporters. Although the regulation of PXR target genes is well-characterized, less is known about the regulation of PXR protein level. By screening an RNAi library, we identified the F-box-only protein 44 (FBXO44) as a novel E3 ligase for PXR. PXR abundance increases upon knockdown of FBXO44, and, inversely, decreases upon overexpression of FBXO44. Further analysis revealed that FBXO44 interacts with PXR, leading to its ubiquitination and proteasomal degradation, and we determined that the F-box associated domain of FBXO44 and the ligand binding domain of PXR are required for the functional interaction. In summary, FBXO44 regulates PXR protein abundance, which has downstream consequences for CYP3A4 levels and drug-drug interactions. The results of this study provide new insight into the molecular mechanisms that regulate PXR protein level and activity and suggest the importance of considering how modulating E3 ubiquitin ligase activities will affect PXR-mediated drug metabolism.

Activation of insulin-like growth factor-1 receptor (IGF-1R) promotes growth of colorectal cancer through triggering the MEX3A-mediated degradation of RIG-I

Insulin-like growth factor-1 receptor (IGF-1R) has been made an attractive anticancer target due to its overexpression in cancers. However, targeting it has often produced the disappointing results as the role played by cross talk with numerous downstream signalings. Here, we report a disobliging IGF-1R signaling which promotes growth of cancer through triggering the E3 ubiquitin ligase MEX3A-mediated degradation of RIG-I. The active β-arrestin-2 scaffolds this disobliging signaling to talk with MEX3A. In response to ligands, IGF-1Rβ activated the basal βarr2 into its active state by phosphorylating the interdomain domain on Tyr64 and Tyr250, opening the middle loop (Leu130‒Cys141) to the RING domain of MEX3A through the conformational changes of βarr2. The models of βarr2/IGF-1Rβ and βarr2/MEX3A could interpret the mechanism of the activated-IGF-1R in triggering degradation of RIG-I. The assay of the mutants βarr2Y64A and βarr2Y250A further confirmed the role of these two Tyr residues of the interlobe in mediating the talk between IGF-1Rβ and the RING domain of MEX3A. The truncated-βarr2 and the peptide ATQAIRIF, which mimicked the RING domain of MEX3A could prevent the formation of βarr2/IGF-1Rβ and βarr2/MEX3A complexes, thus blocking the IGF-1R-triggered RIG-I degradation. Degradation of RIG-I resulted in the suppression of the IFN-I-associated immune cells in the TME due to the blockade of the RIG-I-MAVS-IFN-I pathway. Poly(I:C) could reverse anti-PD-L1 insensitivity by recovery of RIG-I. In summary, we revealed a disobliging IGF-1R signaling by which IGF-1Rβ promoted cancer growth through triggering the MEX3A-mediated degradation of RIG-I.

TRIB3 promotes pulmonary fibrosis through inhibiting SLUG degradation by physically interacting with MDM2

Pulmonary fibrosis (PF) is the pathological structure of incurable fibroproliferative lung diseases that are attributed to the repeated lung injury-caused failure of lung alveolar regeneration (LAR). Here, we report that repetitive lung damage results in a progressive accumulation of the transcriptional repressor SLUG in alveolar epithelial type II cells (AEC2s). The abnormal increased SLUG inhibits AEC2s from self-renewal and differentiation into alveolar epithelial type I cells (AEC1s). We found that the elevated SLUG represses the expression of the phosphate transporter SLC34A2 in AEC2s, which reduces intracellular phosphate and represses the phosphorylation of JNK and P38 MAPK, two critical kinases supporting LAR, leading to LAR failure. TRIB3, a stress sensor, interacts with the E3 ligase MDM2 to suppress SLUG degradation in AEC2s by impeding MDM2-catalyzed SLUG ubiquitination. Targeting SLUG degradation by disturbing the TRIB3/MDM2 interaction using a new synthetic staple peptide restores LAR capacity and exhibits potent therapeutic efficacy against experimental PF. Our study reveals a mechanism of the TRIB3-MDM2-SLUG-SLC34A2 axis causing the LAR failure in PF, which confers a potential strategy for treating patients with fibroproliferative lung diseases.

The E3 ubiquitin ligase NEDD4-1 protects against acetaminophen-induced liver injury by targeting VDAC1 for degradation

Acetaminophen (APAP) overdose is a major cause of liver injury. Neural precursor cell expressed developmentally downregulated 4-1 (NEDD4-1) is an E3 ubiquitin ligase that has been implicated in the pathogenesis of numerous liver diseases; however, its role in APAP-induced liver injury (AILI) is unclear. Thus, this study aimed to investigate the role of NEDD4-1 in the pathogenesis of AILI. We found that NEDD4-1 was dramatically downregulated in response to APAP treatment in mouse livers and isolated mouse hepatocytes. Hepatocyte-specific NEDD4-1 knockout exacerbated APAP-induced mitochondrial damage and the resultant hepatocyte necrosis and liver injury, while hepatocyte-specific NEDD4-1 overexpression mitigated these pathological events both in vivo and in vitro. Additionally, hepatocyte NEDD4-1 deficiency led to marked accumulation of voltage-dependent anion channel 1 (VDAC1) and increased VDAC1 oligomerization. Furthermore, VDAC1 knockdown alleviated AILI and weakened the exacerbation of AILI caused by hepatocyte NEDD4-1 deficiency. Mechanistically, NEDD4-1 was found to interact with the PPTY motif of VDAC1 through its WW domain and regulate K48-linked ubiquitination and degradation of VDAC1. Our present study indicates that NEDD4-1 is a suppressor of AILI and functions by regulating the degradation of VDAC1.

Discovery of a first-in-class ANXA3 degrader for the treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a nasty disease with extremely high malignancy and poor prognosis. Annexin A3 (ANXA3) is a potential prognosis biomarker, displaying an excellent correlation of ANXA3 overexpression with patients' poor prognosis. Silencing the expression of ANXA3 effectively inhibits the proliferation and metastasis of TNBC, suggesting that ANXA3 can be a promising therapeutic target to treat TNBC. Herein, we report a first-in-class ANXA3-targeted small molecule (R)-SL18, which demonstrated excellent anti-proliferative and anti-invasive activities to TNBC cells. (R)-SL18 directly bound to ANXA3 and increased its ubiquitination, thereby inducing ANXA3 degradation with moderate family selectivity. Importantly, (R)-SL18 showed a safe and effective therapeutic potency in a high ANXA3-expressing TNBC patient-derived xenograft model. Furthermore, (R)-SL18 could reduce the β-catenin level, and accordingly inhibit the Wnt/β-catenin signaling pathway in TNBC cells. Collectively, our data suggested that targeting degradation of ANXA3 by (R)-SL18 possesses the potential to treat TNBC.

Construction of TRAF6 ubiquitin site 331 mutant colorectal cancer cell stable line and its effect on biological behavior of colorectal cancer cells / 中华肿瘤杂志

Objective: To investigate the effect of ubiquitin mutation at position 331 of tumor necrosis factor receptor related factor 6 (TRAF6) on the biological characteristics of colorectal cancer cells and its mechanism. Methods: lentivirus wild type (pCDH-3×FLAG-TRAF6) and mutation (pCDH-3×FLAG-TRAF6-331mut) of TRAF6 gene expression plasmid with green fluorescent protein tag were used to infect colorectal cancer cells SW480 and HCT116, respectively. The infection was observed by fluorescence microscope, and the expressions of TRAF6 and TRAF6-331mut in cells was detected by western blot. Cell counting kit-8 (CCK-8) and plate cloning test were used to detect the proliferation ability of colorectal cancer cells in TRAF6 group and TRAF6-331mut group, cell scratch test to detect cell migration, Transwell chamber test to detect cell migration and invasion, immunoprecipitation to detect the ubiquitination of TRAF6 and TRAF6-331mut with ubiquitinof lysine binding sites K48 and K63. Western blot was used to detect the effects of TRAF6 and TRAF6-331mut over expression on the nuclear factor kappa-B (NF-κB) and mitogen activated protein kinase mitogen-activated protein kinase (MAPK)/activating protein-1(AP-1) signal pathway. Results: The successful infection of colorectal cancer cells was observed under fluorescence microscope. Western blot detection showed that TRAF6 and TRAF6-331mut were successfully expressed in colorectal cancer cells. The results of CCK-8 assay showed that on the fourth day, the absorbance values of HCT116 and SW480 cells in TRAF6-331mut group were 1.89±0.39 and 1.88±0.24 respectively, which were lower than those in TRAF6 group (2.09±0.12 and 2.17±0.45, P=0.036 and P=0.011, respectively). The results of plate colony formation assay showed that the number of clones of HCT116 and SW480 cells in TRAF6-331mut group was 120±14 and 85±14 respectively, which was lower than those in TRAF6 group (190±21 and 125±13, P=0.001 and P=0.002, respectively). The results of cell scratch test showed that after 48 hours, the percentage of wound healing distance of HCT116 and SW480 cells in TRAF6-331mut group was (31±12)% and (33±14)%, respectively, which was lower than those in TRAF6 group [(43±13)% and (43±7)%, P=0.005 and 0.009, respectively]. The results of Transwell migration assay showed that the migration numbers of HCT116 and SW480 cells in TRAF6-331mut group were significantly lower than those in TRAF6 group (P<0.001 and P<0.002, respectively). The results of Transwell invasion assay showed that the number of membrane penetration of HCT116 and SW480 cells in TRAF6-331mut group was significantly lower than those in TRAF6 group (P=0.008 and P=0.009, respectively). The results of immunoprecipitation detection showed that the ubiquitin protein of K48 chain pulled by TRAF6-331mut was lower than that of wild type TRAF6 in 293T cells co-transfected with K48 (0.57±0.19), and the ubiquitin protein of K63 chain pulled down by TRAF6-331mut in 293T cells co-transfected with K63 was lower than that of wild type TRAF6 (0.89±0.08, P<0.001). Western blot assay showed that the protein expression levels of NF-κB, p-NF-κB and p-AP-1 in TRAF6-331mut-HCT116 cells were 0.63±0.08, 0.42±0.08 and 0.60±0.07 respectively, which were lower than those in TRAF6-HCT116 cells (P=0.002, P<0.001 and P<0.001, respectively). The expression level of AP-1 protein in TRAF6-HCT116 cells was 0.89±0.06, compared with that in TRAF6-HCT116 cells. The difference was not statistically significant (P>0.05). The protein expression levels of NF-κB, p-NF-κB and p-AP-1 in TRAF6-331mut-SW480 cells were 0.50±0.06, 0.51±0.04, 0.48±0.02, respectively, which were lower than those in TRAF6-SW480 cells (all P<0.001). There was no significant difference in AP-1 protein expression between TRAF6-331mut-SW480 cells and TRAF6-SW480 cells. Conclusion: The ubiquitin site mutation of TRAF6 gene at 331 may prevent the binding of TRAF6 and ubiquitin lysine sites K48 and K63, and then affect the expressions of proteins related to downstream NF-κB and MAPK/AP-1 signal pathways, and inhibit the proliferation, migration and invasion of colorectal cancer cells.