Genetic investigation of the ubiquitin-protein ligase E3A gene as putative target in Angelman syndrome

BACKGROUND Angelman syndrome(AS)is caused by maternal chromosomal deletions,imprinting defects,paternal uniparental disomy involving chromosome 15 and the ubiquitin-protein ligase UBE3A gene mutations.However the genetic basis remains unclear for several patients.AIM To investigate the involvement of UBE3A gene in AS and identifying new potential genes using exome sequencing.METHODS We established a cohort study in 50 patients referred to Farhat Hached University Hospital between 2006 and 2021,with a strong suspicion of AS and absence of chromosomal aberrations.The UBE3A gene was screened for mutation detection.Two unrelated patients issued from consanguineous families were subjected to exome analysis.RESULTS We describe seven UBE3A variants among them 3 none previously described including intronic variants c.2220+14T>C(intron14),c.2507+43T>A(Exon15)and insertion in Exon7:c.30-47_30-46.The exome sequencing revealed 22 potential genes that could be involved in AS-like syndromes that should be investigated further.CONCLUSION Screening for UBE3A mutations in AS patients has been proven to be useful to confirm the diagnosis.Our exome findings could rise to new potential alternative target genes for genetic counseling.

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.

Effects of Nephrolithiasis on Serum DNase(Deoxyribonuclease Ⅰ and Ⅱ) Activity and E3 SUMO-Protein Ligase NSE2(NSMCE2) in Malaysian Individuals

Objective Nephrolithiasis is one of the most common disorders of the urinary tract. The aim of this study was to examine a possible relationship between DNase Ⅰ/Ⅱ activity and E3 SUMO-protein ligase NSE2 in the sera of nephrolithiasis patients to evaluate the possibility of a new biomarker for evaluating kidney damage. Methods Sixty nephrolithiasis patients and 50 control patients were enrolled in a case-control study. Their blood urea, creatinine, protein levels and DNase Ⅰ/Ⅱ activity levels were measured by spectrometry. Serum NSMCE2 levels were measured by ELISA. Blood was collected from patients of the government health clinics in Kuantan-Pahang and fulfilled the inclusion criteria. Results The result indicated that mean levels of sera NSMCE2 have a significantly increase（P〈0.01） in patients compared to control group. Compared with control subjects, activities and specific activities of serum DNase Ⅰ and Ⅱ were significantly elevated in nephrolithiasis patients（P〈0.01）. Conclusion This study suggests that an increase in serum concentrations of DNase Ⅰ/Ⅱ and E3 SUMO-protein ligase NSE2 level can be used as indicators for the diagnosis of kidney injury in patients with nephrolithiasis.

Study the effect of kidney stones on serum xanthine oxidase, ecto-5'-nucleotidase activity and E3 SUMO-protein ligase NSE2(NSMCE2) in Malaysian individuals

Objective: To verify possible relations between 5'-nucleotidase, xanthine oxidase to E3 small ubiquitin-like modifier-protein ligase non structural maintenance of chromosomes elements 2 in sera patients with kidney stones and to evaluate the possibility of a new biomarker for the evaluation of kidney damage. Methods: A sixty patients with known kidney stones who appeared the government health clinics in Kuantan–Pahang and fifty apparently healthy were taken as control group. The 5'-nucleotidase,xanthine oxidase and other biochemical parameters were measured by colorimetric tests. The serum NSMCE2 were measured by enzyme linked immunosorbent assay.Results: The mean serum xanthine oxidase [(39.98±19.70) IU/L] and ecto-5'-nucleotidase activity(40.03±9.53 IU/L) were significantly higher than the controls' levels of(18.04 ±6.26) and(16.06 ±4.61) IU/L respectively. There were 85.00% and 83.33%, of patients with kidney stones who had abnormal ecto-5'-nucleotidase activity and uric acid respectively while xanthine oxidase activity was less sensitive 58.33%.Conclusions: The present study suggests that the increase in serum of xanthine oxidase,ecto-5'-nucleotidase activities E3 small ubiquitin-like modifier-protein ligase NSE2 concentration can be used as biomarkers for diagnosis of kidney damage in patients with kidney stone,also in developments of change DNA damage and inflammation disorders in these patients.

Serum E3 SUMO-protein ligase NSE2 level and peroxynitrite related to oxidative stress in nephrolithiasis patients

Objective: To prove probable relations between serum E3 SUMO-protein ligase NSE2(NSMCE2) concentration, peroxynitrite related to oxidative stress in nephrolithiasis patients.Methods: A total of 60 patients with nephrolithiasis and 50 healthy volunteers were involved in this study. Colorimetric method was used to detect blood urea, creatinine, uric acid, protein, albumin, total antioxidant status, total oxidant status, peroxynitrite, nitric oxide and oxidative stress index. Glutathione, NSMCE2 and superoxide dismutase were measured by ELISA.Results: A significant increase in level of peroxynitrite, total oxidant status, NSMCE2 and oxidative stress index in patients was observed, while total antioxidant status and glutathione were significantly decreased.Conclusions: The study concluded that serum NSMCE2 significantly correlated with peroxynitrite and oxidative stress in patients with nephrolithiasis.

沉默Ku70促进PARP1、ligase3和XRCC1在DNA双链断裂染色质聚集

目的研究碱基切除修复途径(base excision repair,BER)关键因子PARP1、ligase3和XRCC1在Ku70缺失的条件下与DNA双链断裂(double-strand break,DSB)所在染色质的结合及抑制PARP1所产生的影响。方法采用可经药物诱导Ku70 shRNA的细胞株,以高效的DNA双链断裂诱导剂刺孢霉素calicheamicin诱导DSB。分离不同组分蛋白联合稳定同位素标记定量差异蛋白组分析法鉴定Ku70下调后在损伤染色质聚集增多的蛋白,Western blot进行验证并检测PARP1抑制剂DIQ对其染色质聚集的影响。结果在药物Doxy作用下,Ku70明显下调,其余蛋白的表达不受影响。稳定同位素标记定量蛋白组学方法鉴定出PARP1、ligase3和XRCC1在Ku70下调后在损伤染色质聚集增多。Western blot进行了验证并显示PARP1、ligase3和XRCC1在损伤染色质的聚集随DSB程度增加而增加。施加PARP1抑制剂DIQ,随着DIQ浓度的上升,ligase3在损伤染色质的聚集逐渐减少。结论沉默Ku70后,PARP1、ligase3和XRCC1在DSB染色质聚集增加,这种聚集与DSB程度变化一致,并且ligase3的染色质聚集具有一定程度的PARP1依赖性。

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 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.

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.

TaGW2L,a GW2-like RING finger E3 ligase,positively regulates heading date in common wheat(Triticum aestivum L.)

RING finger E3 ligases play an important role in regulating plant growth and development by mediating substrate degradation.In this study,we identified TaGW2L,encoding a Grain width and weight2(GW2)-like RING finger E3 ligase,as a novel positive regulator of heading date in wheat(Triticum aestivum L.).TaGW2L exhibited high amino acid sequence similarities with TaGW2 homoeologs,particularly in the conserved RING finger domain.Expression analysis indicated that TaGW2L was constitutively expressed in various wheat tissues.TaGW2L showed transactivation activity in yeast and could interact with the ubiquitin-conjugating enzymes E2_(s).An in vitro ubiquitination assay verified that TaGW2L possessed a similar E3 ligase activity to TaGW2.Overexpression of the TaGW2L-7A homoeolog in wheat led to a significantly earlier heading date under both natural conditions and long-day conditions.Transcriptome analysis revealed that multiple known genes positively regulating wheat heading were significantly upregulated in the TaGW2L-7A-overexpression plants compared with the wild-type control.Together,our findings shed light on the role of TaGW2L in wheat heading date and provide potential applications of TaGW2L for the adaptation improvement of crops.

Genome-wide identification and expression analysis of Gossypium RING-H2 finger E3 ligase genes revealed their roles in fiber development,and phytohormone and abiotic stress responses

Background： RING H2 finger E3 ligase （RH2FE3） genes encode cysteine rich proteins that mediate E3 ubiquitin ligase activity and degrade target substrates. The roles of these genes in plant responses to phytohormones and abiotic stresses are well documented in various species, but their roles in cotton fiber development are poorly understood. To date, genome wide identification and expression analyses of Gossypium hirsutum RH2FE3 genes have not been reported. Methods： We performed computational identification, structural and phylogenetic analyses, chromosomal distribution analysis and estimated KJKs values of G hirsutum RH2FE3 genes. Orthologous and paralogous gene pairs were identified by all versus all BLASTP searches. We predicted cis regulatory elements and analyzed microarray data sets to generate heatmaps at different development stages. Tissue specific expression in cotton fiber, and hormonal and abiotic stress responses were determined by quantitative real time polymerase chain reaction （qRT PCR） analysis. Results： We investigated 140 G hirsutum, 80 G. orboreum, and evolutionary mechanisms and compared them with orthologs 89 G. roimondii putative RH2FB genes and their in Arobidopsis and rice. A domain based analysis of the G hirsutum RH2FE3 genes predicted conserved signature motifs and gene structures. Chromosomal localization showed the genes were distributed across all G hirsutum chromosomes, and 60 duplication events （4 tandem and 56 segmental duplications） and 98 orthologs were detected, cis elements were detected in the promoter regions of G hirsutum RH2FE3 genes. Microarray data and qRT PCR analyses showed that G hirsutum RH2FE3 genes were strongly correlated with cotton fiber development. Additionally, almost all the （brassinolide, gibberellic acid （GA）, indole 3-acetic acid drought, and salt）. dentified genes were up regulated in response to phytohormones （IAA）, and salicylic acid （SA）） and abiotic stresses （cold, heat, Conclusions： The genome wide identification, comprehensive analysis, and characterization of conserved domains and gene structures, as well as phylogenetic analysis, cis element prediction, and expression profile analysis of G hirsutum RH2FE3 genes and their roles in cotton fiber development and responses to plant hormones and abiotic stresses are reported here for the first time. Our findings will contribute to the genome wide analysis of putative RH2FE3 genes in other species and lay a foundation for future physiological and functional research on G hirsutum RH2FE3 genes.

Antiserum Preparation and Specific Detection of Banana RING-E3 Ubiquitin-Protein Ligase

According to the data of banana transcriptome sequencing, an E3 ubiquitin-protein ligase gene was cloned by RT-PCR method using the cDNA sample of banana leaves. The complete ORF of E3 ubiquitin-protein ligase is 681 bp long and its encoded protein showed 100% sequence identity to homologue RING-H2 finger protein (XP_009407047.1) of Musa_acuminata. Bioinformatic analysis indicated that E3 ubiquitin-protein ligase contains the Ring finger domain in C terminus and eight cross-brace motifs are found in the domain. The target gene was digested by EcoR V and EcoR I, and was inserted into prokaryotic expression vector pET-32a of the same digestions to obtain the plasmid pET32a-E3 ubiquitin-protein ligase. The recombinant plasmid was introduced into Escherichia coli strain BL21 (DE3), and induced at 25°C with 0.4 mmol/L IPTG for 6 hours. The soluble fusion protein was expressed and high purity fusion protein was obtained by Ni2+-NTA agarose affinity chromatography purification. The fusion protein was injected into mice 3 times to prepare the antiserum. Western blot analysis showed a specific protein band was detected in total protein sample of banana leaves, but not for the samples of wild-type Nicotiana benthamiana (N.B.) and wild-type Arabidopsis thaliana (A.T.), implying the antiserum was specific to banana E3 ubiquitin-protein ligase.

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。

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.

SUMO-2/3与孕激素受体的共价结合及其对该受体转录活性的调节

目的研究B型孕激素受体(progesterone receptor B type;PRB)是否能被SUMO-2、SUMO-3类泛素化修饰,并探讨这种修饰对孕激素受体转录活性的影响。方法以人的MCF-7 cDNA为模板进行PCR反应,扩增出SUMO-2、SUMO-3的cDNA,构建真核表达载体pcDNA3FLAG-SUMO2与pcDNA3FLAG-SUMO3;将质粒pXJ40-myc-PRB分别与pcDNA3-FLAG、pcDNA3FLAG-SUMO2、pcDNA3FLAG-SUMO3共转染人胚肾细胞293T,运用免疫共沉淀及western印迹的方法检测其是否发生类泛素化修饰;运用测定荧光素酶报告基因的方法检测类泛素化修饰对孕激素受体转录活性的影响。结果构建成功表达载体pcDNA3FLAG-SUMO2与pcDNA3FLAG-SUMO3;免疫共沉淀实验证实sumo2/3均可以与PRB共价结合;SUMO-2、SUMO-3能以孕激素依赖的方式增强PRB的转录活性。结论 SUMO-2、SUMO-3分子能够对孕激素受体PRB进行类泛素化修饰,并调节其分子功能。

SUMO-1共价修饰ataxin-3

为了探讨ataxin-3的正常生理功能以及脊髓小脑型共济失调Ⅲ型/马查多-约瑟夫病的发病机理,采用酵母双杂交技术,选择polyQ扩展突变型ataxin-3全长构建诱饵质粒,筛选成人脑cDNA文库,寻找与之相互作用的蛋白质,筛选到互作蛋白smallubiquitin-likemodifier1(SUMO-1).进一步运用免疫共沉淀技术证实,SUMO-1在哺乳动物细胞中共价修饰野生型和polyQ扩展突变型ataxin-3.免疫荧光共定位实验发现,polyQ扩展突变型ataxin-3形成的核内蛋白聚合体与SUMO-1共定位.研究提示,ataxin-3的正常生理功能可能受SUMO-1的调节,SUMO-1可能参与了脊髓小脑型共济失调Ⅲ型/马查多-约瑟夫病的发病机制.

人SUMO-3基因原核表达及多克隆抗体制备

构建人SUMO-3基因的原核表达载体pET41a(+)-SUMO-3,表达重组GST-SUMO-3融合蛋白,制备人SUMO-3多克隆抗体。试验结果显示,通过PCR方法从重组质粒pEYFP-SUMO-3中克隆到的SUMO-3N端93个氨基酸的基因序列与NCBI上提供的序列一致,重组质粒pET41a(+)-SUMO-3构建成功;重组pET41a(+)-SUMO-3在E.coli.BL21(DE3)pLysS中表达GST-SUMO-3融合蛋白,分子量为44.0 kDa,与预期分子量一致;采用亲和层析纯化融合蛋白GST-SUMO-3并免疫家兔,获得人SUMO-3抗体;Westernblot检测显示该抗体可以特异性识别SUMO-3,ELISA检测结果成阳性,抗体效价约为1∶20000。实验结果为进一步研究人SUMO-3及SUMO第二类家族的功能提供了有用工具。

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).

An atypical ubiquitin ligase at the heart of neural development and programmed axon degeneration

The degeneration of nerve fibres following injury was first described by Augustus Waller over 170 years ago.Initially assumed to be a passive process,it is now evident that axons respond to insult via regulated cellular signaling events resulting in their programmed degeneration.Pro-survival and prodegenerative factors have been identified and their regulato ry mechanisms are beginning to emerge.The ubiquitin system has been implicated in the pro-degenerative process and a key component is the ubiquitin E3 ligase MYCBP2(also known as PHR1).Ubiquitin E3 ligases are tasked with the transfer of the small protein modifier ubiquitin to substrates and consist of hundreds of members.They can be classified as single subunit systems or as multi-subunit complexes.Their catalytic domains can also be assigned to three general architectures.Hints that MYCBP2 might not conform to these established formats came to light and it is now clear from biochemical and structural studies that MYCBP2 is indeed an outlier in terms of its modus operandi.Furthermore,the unconventional way in which MYCBP2 transfe rs ubiquitin to substrates has been linked to neurodevelopmental and pro-degenerative function.Herein,we will summarize these research developments relating to the unusual features of MYCBP2 and postulate therapeutic strategies that prevent Walle rian degeneration.These have exciting potential for providing relief from pathological neuropathies and neurodegenerative diseases.