The E3 ubiquitin ligase seven in absentia homolog 1 may be a potential new therapeutic target for Parkinson's disease

In this study, we investigated the effect of an antibody against E3 ubiquitin ligase seven in absentia homolog 1（SIAH-1） in PC12 cells. 1-Methyl-4-phenylpyridinium（MPP＋） treatment increased α-synuclein, E1 and SIAH-1 protein levels in PC12 cells, and it reduced cell viability; however, there was no significant change in light chain 3 expression. Treatment with an SIAH-1 antibody decreased m RNA expression levels of α-synuclein, light chain 3 and SIAH-1, but increased E1 m RNA expression. It also increased cell viability. Combined treatment with MPP＋ and rapamycin reduced SIAH-1 and α-synuclein levels. Treatment with SIAH-1 antibody alone diminished α-synuclein immunoreactivity in PC12 cells, and reduced the colocalization of α-synuclein and light chain 3. These findings suggest that the SIAH-1 antibody reduces the monoubiquitination and aggregation of α-synuclein, promoting its degradation by the ubiquitin-proteasome pathway. Consequently, SIAH-1 may be a potential new therapeutic target for Parkinson’s disease.

Research Progress in Function and Regulation of E3 Ubiquitin Ligase SMURF1

Smad ubiquitylation regulatory factor 1(Smurf1)is an important homologous member of E6-AP C-terminus type E3 ubiquitin ligase.Initially,Smurf1 was reportedly involved in the negative regulation of the bone morphogenesis protein(BMP)pathway.After further research,several studies have confirmed that Smurf1 is widely involved in various biological processes,such as bone homeostasis regulation,cell migration,apoptosis,and planar cell polarity.At the same time,recent studies have provided a deeper understanding of the regulatory mechanisms of Smurf1’s expression,activity,and substrate selectivity.In our review,a brief summary of recent important biological functions and regulatory mechanisms of E3 ubiquitin ligase Smurf1 is proposed.

Molecular cloning and functional characterization of apple U-box E3 ubiquitin ligase gene MdPUB29 reveals its involvement in salt tolerance

An E3 ubiquitin ligase gene(Genbank accession no.:MD01 G1010900) was cloned from the Royal Gala apple genome(Malus×domestica Borkh.).Sequence analysis showed that the length of the MdPUB29 gene was 1 275 bp,encoding 424 amino acids.Phylogenetic tree analysis indicated that the apple E3 ubiquitin ligase exhibited the greatest sequence similarity to Pyrus×bretschneideri.The predicted protein structural domain of MdPUB29 showed that it contained a U-box domain.qRT-PCR analysis showed that Md PUB29 was expressed widely in different tissues of the Royal Gala apple species,and was highly expressed in the root,while the expression of MdPUB29 was significantly inhibited by exogenous NaCl.Immunoblotting assays revealed that MdPUB29 protein abundance in tissue cultures of the Royal Gala apple accumulated under NaC l stress conditions.Three-dimensional protein structure prediction indicated that MdPUB29 was highly homologous with AtPUB29.The growing potential of MdPUB29-expressing apple calli and Arabidopsis were much stronger than that of the control under salt stress conditions,suggesting that MdPUB29 may positively regulate salt tolerance.

Role of E3 ubiquitin ligases in lung cancer

E3 ubiquitin ligases are a large family of proteins that catalyze the ubiquitination of many protein substrates for targeted degradation by the 26S proteasome.Therefore,E3 ubiquitin ligases play an essential role in a variety of biological processes including cell cycle regulation,proliferation and apoptosis.E3 ubiquitin ligases are often found overexpressed in human cancers,including lung cancer,and their deregulation has been shown to contribute to cancer development.However,the lack of specific inhibitors in clinical trials is a major issue in targeting E3 ubiquitin ligases with currently only one E3 ubiquitin ligase inhibitor being tested in the clinical setting.In this review,we focus on E3 ubiquitin ligases that have been found deregulated in lung cancer.Furthermore,we discuss the processes in which they are involved and evaluate them as potential anti-cancer targets.By better understanding the mechanisms by which E3 ubiquitin ligases regulate biological processes and their exact role in carcinogenesis,we can improve the development of specific E3 ubiquitin ligase inhibitors and pave the way for novel treatment strategies for cancer patients.

Role of E3 ubiquitin ligases in gastric cancer

E3 ubiquitin ligases have an important role in carcinogenesis and include a large family of proteins that catalyze the ubiquitination of many protein substrates for targeted degradation by the 26S proteasome.So far,E3 ubiquitin ligases have been reported to have a role in a variety of biological processes including cell cycle regulation,cell proliferation,and apoptosis.Recently,several kinds of E3 ubiquitin ligases were demonstrated to be generally highly expressed in gastric cancer(GC) tissues and to contribute to carcinogenesis.In this review,we summarize thecurrent knowledge and information about the clinical significance of E3 ubiquitin ligases in GC.Bortezomib,a proteasome inhibitor,encouraged the evaluation of other components of the ubiquitin proteasome system for pharmaceutical intervention.The clinical value of novel treatment strategies targeting aberrant E3 ubiquitin ligases for GC are discussed in the review.

Human RING finger protein ZNF645 is a novel testis-specific E3 ubiquitin ligase

A large number of testis-specific genes are involved in the complex process of mammalian spermatogenesis. Identification of these genes and their roles is important for understanding the mechanisms underlying spermatogenesis. Here we report on a novel human RING finger protein, ZNF645, which contains a C3HC4 RING finger domain, a C2H2 zinc-finger domain, and a proline-rich region, indicating that it has a structure similar to that of the c-Cbl-like protein Hakai. ZNF645 was exclusively expressed in normal human testicular tissue. Immunohistochemical analysis confirmed that ZNF645 protein was present in spermatocytes, round and elongated spermatids, and Leydig cells. Immunofluorescence staining of mature sperms further showed that the ZNF645 protein was localized over the postacrosomal perinuclear theca region and the entire length of sperm tail. An in vitro ubiquitination assay indicated that the RING finger domain of the ZNF645 protein had E3 ubiquitin ligase activity. Therefore, we suggest that ZNF645 might act as an E3 ubiquitin-protein ligase and play a role in human sperm production and quality control.

烟草E3泛素连接酶NtHOS1a和NtHOS1b基因的克隆与表达分析

为明确与烟草低温早花有关的调控基因,利用生物信息学方法结合RT-PCR和SMART RACE技术,从烟草中克隆了2个E3泛素蛋白连接酶HOS1基因cDNA全长序列,分别命名为NtHOS1a(Gen Bank登录号:KU558689)和NtHOS1b(Gen Bank登录号:KU558690)。NtHOS1a基因全长为3 599 bp,编码963个氨基酸;NtHOS1b基因全长为3 578 bp,编码954个氨基酸;两基因氨基酸序列的一致性为95%,与拟南芥HOS1蛋白(NP_181511)的序列一致性分别为51%和50%。两基因编码蛋白的N末端均含有一个E3泛素连接酶特征的环指结构域。荧光定量PCR分析表明:在正常生长条件下,NtHOS1a和NtHOS1b在烟草根、茎、叶中表达强烈,12℃低温处理10 d后两基因在烟草根、茎、叶中的表达量均有不同程度的降低,说明在烟草根、茎、叶组织中NtHOS1a和NtHOS1b的表达量受低温胁迫的负向调控。

Dynamic modulation of nodulation factor receptor levels by phosphorylation-mediated functional switch of a RING-type E3 ligase during legume nodulation

The precise control of receptor levels is crucial for initiating cellular signaling transduction in response to specific ligands;however,such mechanisms regulating nodulation factor(NF)receptor(NFR)-mediated perception of NFs to establish symbiosis remain unclear.In this study,we unveil the pivotal role of the NFR-interacting RING-type E3 ligase 1(NIRE1)in regulating NFR1/NFR5 homeostasis to optimize rhizobial infection and nodule development in Lotus japonicus.We demonstrated that NiRE1 has a dual function in this regulatory process.It associates with both NFR1 and NFR5,facilitating their degradation through K48-linked polyubiquitination before rhizobial inoculation.However,following rhizobial inoculation,NFR1 phosphorylates NIRE1ata conserved residue,Tyr-109,inducing a functional switch in NIRE1,which enables NIRE1tomediateK63-linkedpolyubiquitination,thereby stabilizing NFR1/NFR5 in infected root cells.The introduction of phospho-dead NIRE1Y1osF leads to delayed nodule development,underscoring the significance of phosphorylation at Tyr-1o9 in orchestrating symbiotic processes.Conversely,expression of the phospho-mimic NIRE1Y0E results in the formation of spontaneous nodules in L.japonicus,further emphasizing the critical role of the phosphorylation-dependent functional switch in NiRE1.In summary,these findings uncover a fine-tuned symbiotic mechanism that a single E3 ligase could undergo a phosphorylationdependent functional switch to dynamically and precisely regulate NF receptor protein levels.

Expression Pattern, Interaction Network, and Functional Analysis of the Arabidopsis Botrytis Susceptible1 Interactor

E3 ubiquitin ligases are participated in numerous processes, regulating the response to biotic and abiotic stresses. Botrytis susceptible1 interactor (BOI) is a RING (Really Interesting New Gene)-type E3 ligase that mediates the ubiquitination of BOS1 (Botrytis susceptible1), a transcription factor involved in stress and pathogen responses. Although BOI is an E3 ligase, there are reports to show that BOI interacts with target proteins such as DELLAs or CONSTANS to repress gibberellin responses and flowering without the degradation of the target proteins. In this article, we utilize diversified methods to comprehensively analyze the expression pattern, interaction network and function of BOI gene. Firstly, 1800 bp upstream region of BOI gene from Arabidopsis thaliana (Arabidopsis) genome was isolated, and fused GUS reporter gene. The resulting expression cassette was introduced into wild-type Arabidopsis through Agrobacterium-mediated transformation. The result demonstrated that BOI gene was expressed predominantly in leaves, siliques, young roots, and flowering tissues, indicating that BOI gene may be involved in multiple processes in plant growth and development in Arabidopsis. Besides, eight candidate interacting proteins were obtained from the Arabidopsis cDNA library via yeast two-hybrid technology, including EXO70E2 (AT5G61010), WRKY7 (AT4G24240), WRKY11 (AT4G31550), WRKY17 (AT2G24570), UBP20 (AT4G17895), L5 (AT1G12290), SAUR9 (AT4G36110) and TCP21 (AT5G08330). Functional analysis of these candidate interacting proteins manifested that they related to multiple pathways, including biological and abiotic stress, programmed cell death, protein degradation, material metabolism and transcriptional regulation. In addition, the results of the transient assay proclaimed that BOI protein affects the protein stability of EXO70E2 and L5 through its E3 ubiquitin ligase activity. Our results provide novel clues for a better understanding of molecular mechanisms underlying BOI-mediated regulations.

射血分数保留心力衰竭患者血清WWP1和NLRP3的表达水平及其临床价值研究

目的 探讨WW结构域E3泛素蛋白连接酶1(WW domain-containing E3 ubiquitin protein ligase 1,WWP1)和核苷酸结合寡聚化结构域样受体蛋白3(nucleotide-binding oligomerization domain-like receptor protein 3,NLRP3)在射血分数保留心力衰竭(heart failure with preserved ejection fraction,HFpEF)患者血清中的表达水平及临床意义。方法选取华北医疗健康集团峰峰总医院2021年1月~2022年9月收治的153例HFpEF患者为观察组,并根据患者纽约心脏病协会(New York Heart Association,NYHA)心功能分级分为心功能分级Ⅰ~Ⅱ级组(n=64)和心功能分级Ⅲ~Ⅳ级组(n=89),另选取同期体检健康的148例志愿者为对照组。血清WWP1,NLRP3水平与患者心功能指标的相关性采用Pearson分析;受试者工作特征(receiver operating characteristic,ROC)曲线分析血清WWP1和NLRP3水平对HFpEF患者心衰严重程度的诊断价值。结果 与对照组比较,观察组血清WWP1(1.68±0.35 vs 1.04±0.19)和NLRP3(6.72±1.26 ng/ml vs 4.57±0.84 ng/ml)表达水平明显升高,差异具有统计学意义(t=19.623,17.359,均P <0.05);与心功能分级Ⅰ~Ⅱ级组比较,心功能分级Ⅲ~Ⅳ级组血清WWP1(1.87±0.39 vs 1.42±0.32)和NLRP3(7.53±1.40 ng/ml vs 5.59±1.18 ng/ml)表达水平明显升高,差异具有统计学意义(t=7.744,9.017,均P<0.05);心功能分级Ⅰ~Ⅱ级组与心功能分级Ⅲ~Ⅳ级组心率、左心房内径(left atrial diameter,LAD)、左心室舒张末期内径(left ventricular end-diastolic diameter,LVEDD)、左室舒张末期后壁厚度(left ventricular end-diastolic posterior wall thickness,LVPWT)、左心室射血分数(left ventricular ejection fraction,LVEF)、二尖瓣舒张早期流速峰值(peak mitral early diastolic velocity,E)/舒张晚期流速峰值(peak late diastolic velocity,A)以及心房颤动发生率比较差异均具有统计学意义(t/χ^(2)=2.757~7.069,均P <0.05);HFpEF患者血清WWP1水平与LAD,LVEDD,LVPWT呈正相关(r=0.547,0.471,0.536,均P <0.05),与LVEF和E/A呈负相关(r=-0.485,-0.417,均P <0.05);血清NLRP3水平与LAD,LVEDD,LVPWT呈正相关(r=0.534,0.494,0.520,均P <0.05),与LVEF和E/A呈负相关(r=-0.462,-0.523,均P <0.05)。ROC结果显示,血清WWP1和NLRP3水平单独诊断HFpEF患者心衰严重程度的曲线下面积(area under the curve,AUC)分别为0.825和0.855,两者联合诊断的AUC(0.924)显著大于血清WWP1和NLRP3水平单独诊断的AUC(Z=3.600,P<0.001;Z=3.053,P=0.002)。结论 血清WWP1和NLRP3水平在HFpEF患者中明显升高,且与患者心功能密切相关,血清WWP1和NLRP3对HFpEF患者心衰严重程度具有一定的诊断价值。

血清sTREM-1、sTim3、cullin4A与肺结核患者肺部受累情况的相关性

目的研究血清可溶性髓系细胞触发受体-1(sTREM-1)、可溶性T细胞免疫球蛋白黏蛋白3(sTim-3)、泛素连接酶4A(cullin4A)在反映4MRZE化疗方案的疗效及肺结核患者肺部受累情况中的价值。方法将2018年1月至2021年1月武汉市金银潭医院及赤壁市人民医院收治的265例肺结核患者根据治疗方案的不同分为采用2H3R3Z3E3/4H3R3标准四联疗法方案治疗的对照组(n=97)、4MRZE超短程化疗方案治疗的4MRZE组(n=88)和2HRZE/4HR方案治疗的2HRZE/4HR组(n=80)。比较3组治疗后临床疗效,以及治疗前和治疗2、4个月血清sTREM-1、sTim3、cullin4A水平变化,分析血清sTREM-1、sTim3、cullin4A在反映肺结核患者肺部受累情况中的价值。结果4MRZE组、2HRZE/4HR组治疗2、4个月时的痰菌转阴率及病灶有效吸收率均高于对照组(P<0.05),且4MRZE组高于2HRZE/4HR组(P<0.05);在治疗过程中,3组患者血清sTREM-1、sTim3呈下降趋势,而cullin4A mRNA呈上升趋势,且4MRZE组患者治疗2、4个月的血清sTREM-1、sTim3显著低于2HRZE/4HR组、对照组(P<0.05),而cullin4A mRNA显著高于2HRZE/4HR组、对照组(P<0.05)。但是治疗完成后,3组痰菌转阴率、病灶有效吸收率,以及血清sTREM-1、sTim3水平比较,差异无统计学意义(P>0.05)。结论4MRZE化疗方案在肺结核治疗中具备治疗周期短的同时保证治疗效果良好的优点。血清sTREM-1、sTim3、cullin4A水平在反映痰菌转阴及病灶有效吸收中具有一定价值。

Study on effect of imbalance of TRAF-6, IRAK-1 and NALP3 inflammatory factors in patients with gouty arthritis

Objective:To explore the effect of imbalance of tumor necrosis factor receptor related factor-6(TRAF-6),interleukin 1 receptor associated kinase-1(IRAK-1)and neutrophil alkaline phosphatase-3(NALP3)in patients with gouty arthritis.Methods:The retrospective experiment was conducted on 105 patients with gouty arthritis admitted to our hospital(47 patients with acute onset and 58 patients with remission,namely group A and group B);meanwhile,another 61 healthy volunteers were selected for control,namely group C.The enrolling of the three groups was dated from May 2017 to May 2018,and TRAF-6,IRAK-1 and NALP3 of all subjects were tested through real-time fluorescence quantification(RT-PCR),and the correlation between the three inflammatory factors and gouty arthritis was compared.Results:1)Through treatment,ESR,BUA and total addiment in group A and B were higher than those in group C,among which the three indicators in group A were higher than those in group B(P<0.05),while CRP was lower than that of group C,and the two indicators in group A were lower than those in group B(P<0.05).2)There was no significant difference in the relative expression of TRAF-6 mRNA between group A and group B before treatment(P>0.05),significantly lower than group C(P<0.05);the above indicators of group A and group B were improved to some extent after treatment,but group A was still lower than group B(P<0.05),and the degree of improvement of group A was also lower than that of group C(P<0.05),while the degree of improvement of group B was not significantly different from that of group C(P>0.05).3)The relative expression level of IRAK-1mRNA in group A and group B before treatment showed no significant difference(P>0.05),but was also lower than that in group C(P<0.05).The relative expression level of IRAK-1mRNA in group A and group B increased to some extent after treatment,with group A significantly lower than group C(P<0.05),and group B showed no significant difference compared with group C(P>0.05).4)The relative expression level of NALP-3 mRNA in group A and group B showed no significant difference(P>0.05)before treatment,significantly higher than that in group C(P<0.05);the relative expression of NALP-3 mRNA in group A was not significantly decreased(P>0.05)after treatment,while that in group B was significantly decreased after treatment(P<0.05),indicating significant different compared with group A and group C.5)There was no correlation between)TRAF-6,ESR,CRP and total addiment(P>0.05);IRAK-1 was negatively correlated with CRP,BUA and total addiment(P<0.05);NALP-3 was negatively correlated with ESR and CRP(P<0.05).Conclusion:TRAF-6,IRAK-1 and NALP-3 are all under abnormal expression in the developing of new gouty arthritis,acting as important participants in promoting the occurrence,development and outcome of illness states,so the intervening measures should be taken.

Jianpi Decoction Combined with Medroxyprogesterone Acetate Alleviates Cancer Cachexia and Prevents Muscle Atrophy by Directly Inhibiting E3 Ubiquitin Ligase

ObjectiveTo provide comprehensive evidence for the anti-cancer cachexia effect of Jianpi Decoction(JP)and to explore its mechanism of anti-cancer cachexia.MethodsA mouse model of colon cancer(CT26)-induced cancer cachexia(CC)was used to investigate the anti-CC effect of JP combined with medroxyprogesterone acetate(MPA).Thirty-six mice were equally divided into 6 groups:normal control,CC,MPA(100 mg·kg^(−1)·d^(−1)),MPA+low-dose(20 mg·kg^(−1)·d^(−1))JP(L-JP),MPA+medium-dose(30 mg·kg^(−1)·d^(−1))JP(M-JP),and MPA+high-dose(40 mg·kg^(−1)·d^(−1))JP(H-JP)groups.After successful modeling,the mice were administered by gavage for 11 d.The body weight and tumor volume were measured and recorded every 2 d starting on the 8th day after implantation.The liver,heart,spleen,lung,kidney,tumor and gastrocnemius muscle of mice were collected and weighed.The pathological changes of the tumor was observed,and the cross-sectional area of the gastrocnemius muscle was calculated.The protein expressions of STAT3 and E3 ubiquitinase in the gastrocnemius muscle were measured by Western blot.In addition,an in vitro C2C12 myotube formation model was established to investigate the role of JP in hindering dexamethasone-induced muscle atrophy.In vitro experiments were divided into control,model,and JP serum groups.After 2-d administration,microscopic photographs were taken and myotube diameters were calculated.Western blot was performed to measure the protein expressions of STAT3 and E3 ubiquitinase.ResultsJP combined with MPA restored tumor-induced weight loss(P<0.05,vs.CC)and muscle fiber size(P<0.01,vs.CC).Mechanistically,JP reduced the expression of atrophy-related proteins MuRF1 and MAFbx in tumor-induced muscle atrophy in vivo(P<0.05,vs.CC).In addition,JP reduced the expression of atrophy-related proteins MuRF1 and MAFbx and p-STAT3 phosphorylation(P<0.05 or P<0.01 vs.model group)in C2C12 myotubes treated with dexamethasone in vitro.ConclusionsAdministration of JP combined with MPA restores tumor-induced cachexia conditions.In addition,the profound effect of JP combined with MPA on tumor-induced cachexia may be due to its inhibition of muscle proteolysis(E3 ubiquitinase system).

RNF31表达下调抑制TNF-α刺激的NF-κB通路的激活

目的利用慢病毒干涉下调内源性RNF31表达,研究NF-κB通路的活化及对细胞凋亡的影响。方法将人RNF31的shRNA片段克隆到慢病毒表达载体p Green Puro中,瞬时转染HEK293T细胞,筛选出有效的干涉片段。将重组表达质粒与包装质粒PMD、SPA共转染293T细胞,在24 h、48 h分2次收集慢病毒上清,用流式细胞术检测病毒滴度。将获得的病毒感染HEK293细胞,提取细胞蛋白,Real-time PCR以及Western Blot检测RNF31干涉效果;报告基因实验检测敲低RNF31对NF-κB转录活性的影响;Real-time PCR检测干涉RNF31对TNF-α诱导的NF-κB下游靶基因的影响;Western Blot检测下调RNF31对IκBα活化的影响;Hochest染色检测下调RNF31对细胞凋亡的影响。结果成功构建RNF31干涉慢病毒p Green Puro-RNF31载体并获得慢病毒颗粒,病毒滴度可达3×107pfu/ml。在HEK293细胞中下调RNF31,抑制TNF-α刺激的NF-κB的转录活性,并抑制NF-κB下游靶基因的表达;下调RNF31抑制TNF-α刺激的IκBα的活化;此外,在TNF-α刺激细胞24 h时,RNF31表达下调使细胞凋亡增多。结论 RNF31表达下调抑制TNF-α刺激的NF-κB通路的激活。

Arabidopsis U-box E3 ubiquitin ligase PUB11 negatively regulates drought tolerance by degrading the receptor-like protein kinases LRR1 and KIN7

Both plant receptor-like protein kinases(RLKs)and ubiquitin-mediated proteolysis play crucial roles in plant responses to drought stress.However,the mechanism by which E3 ubiquitin ligases modulate RLKs is poorly understood.In this study,we showed that Arabidopsis PLANT U-BOX PROTEIN 11(PUB11),an E3 ubiquitin ligase,negatively regulates abscisic acid(ABA)-mediated drought responses.PUB11 interacts with and ubiquitinates two receptor-like protein kinases,LEUCINE RICH REPEAT PROTEIN 1(LRR1)and KINASE 7(KIN7),and mediates their degradation during plant responses to drought stress in vitro and in vivo.pub11 mutants were more tolerant,whereas Irr1 and kin7 mutants were more sensitive,to drought stress than the wild type.Genetic analyses show that the pub11 Irr1 kin7 triple mutant exhibited similar drought sensitivity as the Irr1 kin7 double mutant,placing PUB11 upstream of the two RLKs.Abscisic acid and drought treatment promoted the accumulation of PUB11,which likely accelerates LRR1 and KIN7 degradation.Together,our results reveal that PUB11 negatively regulates plant responses to drought stress by destabilizing the LRR1 and KIN7 RLKs.

Negative feedback regulation of cellular antiviral signaling by RBCKl-mediated degradation of IRF3

Viral infection causes host cells to produce type I interferons （IFNs）, which are critically involved in viral clearance. Previous studies have demonstrated that activation of the transcription factor interferon regulatory factor （IRF）3 is essential for virus-triggered induction of type I IFNs. Here we show that the E3 ubiquitin ligase RBCC protein interacting with PKC1 （RBCK1） catalyzes the ubiquitination and degradation of IRF3. Overexpression of RBCK1 negatively regulates Sendai virus-triggered induction of type I IFNs, while knockdown of RBCK1 has the opposite effect. Plaque assays consistently demonstrate that RBCKI negatively regulates the cellular antiviral response. Furthermore, viral infection leads to induction of RBCK1 and subsequent degradation of IRF3. These findings suggest that the cellular antiviral response is controlled by a negative feedback regulatory mechanism involving RBCKl-mediated ubiquitination and degradation of IRF3.

Role of SKP1-CUL1-F-Box-Protein (SCF) E3 Ubiquitin Ligases in Skin Cancer

Many biological processes such as cell proliferation, differentiation, and cell death depend precisely on the timely synthesis and degradation of key regulatory proteins. While protein synthesis can be regulated at multiple levels, protein degradation is mainly controlled by the ubiquitin-proteasome system （UPS）, which consists of two distinct steps： （1） ubiquitylation of targeted protein by E1 ubiquitin-activating enzyme, E2 ubiquitin-conjugating enzyme and E3 ubiquitin ligase, and （2） subsequent degradation by the 26S proteasome. Among all E3 ubiquitin ligases, the SCF （SKP1-CUL1-F-box protein） E3 ligases are the largest family and are responsible for the turnover of many key regulatory proteins. Aberrant regulation of SCF E3 ligases is associated with various human diseases, such as cancers, including skin cancer. In this review, we provide a comprehensive overview of all currently published data to define a promoting role of SCF E3 ligases in the development of skin cancer. The future directions in this area of research are also discussed with an ultimate goal to develop small molecule inhibitors of SCF E3 ligases as a novel approach for the treatment of human skin cancer. Furthermore, altered components or substrates of SCF E3 ligases may also be developed as the biomarkers for early diagnosis or predicting prognosis.

The E3 ubiquitin ligase HUWE1 acts through the N-Myc-DLL1-NOTCH1 signaling axis to suppress glioblastoma progression

Background:Elucidation of the post-transcriptional modification has led to novel strategies to treat intractable tumors,especially glioblastoma(GBM).The ubiquitin-proteasome system(UPS)mediates a reversible,stringent and stepwise post-translational modification which is closely associated with malignant processes of GBM.To this end,developing novel therapeutic approaches to target the UPS may contribute to the treatment of this disease.This study aimed to screen the vital and aberrantly regulated component of the UPS in GBM.Based on the molecular identification,functional characterization,and mechanism investigation,we sought to elaborate a novel therapeutic strategy to target this vital factor to combat GBM.Methods:We combined glioma datasets and human patient samples to screen and identify aberrantly regulated E3 ubiquitin ligase.Multidimensional database analysis and molecular and functional experiments in vivo and in vitro were used to evaluate the roles of HECT,UBA and WWE domain-containing E3 ubiquitin ligase 1(HUWE1)in GBM.dCas9 synergistic activation mediator system and recombinant adeno-associated virus(rAAV)were used to endogenously overexpress full-length HUWE1 in vitro and in glioma orthotopic xenografts.Results:Low expression of HUWE1 was closely associated with worse prognosis of GBM patients.The ubiquitination and subsequent degradation of N-Myc mediated by HUWE1,leading to the inactivation of downstream Delta-like 1(DLL1)-NOTCH1 signaling pathways,inhibited the proliferation,invasion,and migration of GBM cells in vitro and in vivo.A rAAV dual-vector system for packaging and delivery of dCas9-VP64 was used to augment endogenous HUWE1 expression in vivo and showed an antitumor activity in glioma orthotopic xenografts.Conclusions:The E3 ubiquitin ligase HUWE1 acts through the N-Myc-DLL1-NOTCH1 signaling axis to suppress GBM progression.Antitumor activity of rAAV dual-vector delivering dCas9-HUWE1 system uncovers a promising therapeutic strategy for GBM.

Phosphorylation of Rictor at Thr1135 impairs the Rictor/Cullin-1 complex to ubiquitinate SGK1

The Rictor/mTOR complex plays a pivotal role in a variety of cellular functions including cellular metabolism,cell proliferation and survival by phosphorylating Akt at Ser473 to fully activate the Akt kinase.However,its upstream regulatory pathways as well as whether it has additional function(s)remain largely unknown.We recently reported that Rictor contains a novel ubiquitin E3 ligase activity by forming a novel complex with Cullin-1,but not with other Cullin family members.Furthermore,we identified SGK1 as its downstream target.Interestingly,Rictor,but not Raptor or mTOR,promotes SGK1 ubiquitination.As a result,SGK1 expression is elevated in Rictor^(–/–)MEFs.We further defined that as a feedback mechanism,Rictor can be phosphorylated by multiple AGC family kinases including Akt,S6K and SGK1.Phosphorylation of Rictor at the Thr1135 site did not affect its kinase activity towards phosphorylating its conventional substrates including Akt and SGK1.On the other hand,it disrupted the interaction between Rictor and Cullin-1.Consequently,T1135E Rictor was defective in promoting SGK1 ubiquitination and destruction.This finding further expands our knowledge of Rictor’s function.Furthermore,our work also illustrates that Rictor E3 ligase activity could be governed by specific signaling kinase cascades,and that misregulation of this process might contribute to SGK overexpression which is frequently observed in various types of cancers.

TRAF-6、IRAK-1和NALP3炎症因子失调在痛风性关节炎患者体内的作用研究

目的:探讨肿瘤坏死因子受体相关因子-6(TRAF-6)、白介素1受体关联激酶-1(IRAK-1)、嗜中性白细胞碱性磷酸酶-3(NALP3)等3种炎症因子失调在痛风性关节炎患者体内的作用。方法:选取本院收治的105例痛风性关节炎患者(急性发作期患者47例,缓解期患者58例,即A、B组)进行回顾性实验,同时选健康志愿者61例进行对照,即C组,3组纳入时间均为2017年5月~2018年5月,所有受试者TRAF-6、IRAK-1和NALP3检测均采用实时荧光定量发法(RT-PCR)完成,并比较这3种炎性因子与痛风性关节炎的相关性。结果:(1)A、B组治疗后的ESR、BUA及总补体均高于C组,其中A组上述3项指标均高于B组(P<0.05),而CRP均低于C组,且A组上述两项指标均低于B组(P<0.05)。(2)A、B组治疗前TRAF-6 mRNA相对表达量比较无明显差异(P<0.05),且低于C组(P<0.05);A、B组治疗后的上述指标均有所提升,但A组依旧低于B组(P<0.05),且A组提升幅度同样低于C组(P<0.05),而B组提升幅度较C组无明显差异(P<0.05)。(3)A、B组治疗前的IRAK-1mRNA相对表达量相比无显著差异(P>0.05),但均低于C组(P<0.05),A、B组治疗后的IRAK-1mRNA相对表达量均有所提升,A组明显低于C组(P<0.05),B组较C组则无明显差异(P>0.05)。(4)A、B组治疗前的NALP-3 mRNA相对表达量相比无明显差异(P>0.05),且高于C组(P<0.05);A组治疗后的NALP-3 mRNA相对表达量下降均不明显(P<0.05),而B组治疗后则明显下降,与A、C组相比均有显著差异(P<0.05)。(5)TRAF-6与ESR、CRP及总补体均无相关性(P>0.05);IRAK-1与CRP、BUA及总补体呈负相关(P<0.05);NALP-3与ESR、CRP呈正相关(P<0.05)。结论:在痛风性关节炎患者的患病过程中,TRAF-6、IRAK-1及NALP-3均呈异常表达状态,是促进患者病情发生、发展和转归的重要参与者,应采取措施进行干预。