Ubiquitin-conjugating enzyme UBE2Q2 participates in HUWE1-mediated protection on renal tubulointerstitial fibrosis / 生理学报

The ubiquitin-proteasome system plays an important role in protein degradation. The process of ubiquitination requires ubiquitin activating enzyme E1, ubiquitin-conjugating enzyme E2, and ubiquitin ligase E3 to complete the coordination. Our previous studies have shown that HUWE1 (HECT, UBA and WWE domain containing 1), as an E3 ubiquitin ligase, can degrade epidermal growth factor receptor (EGFR) to inhibit renal tubulointerstitial fibrosis. However, E2 ubiquitin-conjugating enzymes binding to HUWE1 are still unclear. The aim of the present study was to identify E2 ubiquitin-conjugating enzymes of HUWE1. Real-time PCR was used to identify E2 ubiquitin-conjugating enzyme that may interact with HUWE1. The expression of E2 ubiquitin-conjugating enzyme was detected in kidney of unilateral ureteral obstruction (UUO) mice and HK-2 cells treated with transforming growth factor-β (TGF-β). The results showed that the expressions of E2 ubiquitin-conjugating enzyme UBE2Q2 were significantly down-regulated at both RNA and protein levels in UUO kidneys. The expression of UBE2Q2 was also down-regulated in HK-2 cells stimulated with TGF-β, which was consistent with the change in the expression of HUWE1. These findings indicated that UBE2Q2 expression was synergistic with HUWE1 in the injured kidney. Co-immunoprecipitation (Co-IP) experiments showed that HUWE1 interacted with UBE2Q2 in HK-2 cells. The co-localization of UBE2Q2 and HUWE1 was confirmed by cell immunofluorescence staining. After knocking down UBE2Q2 by siRNA, ubiquitin binding to HUWE1 and EGFR was decreased. In sum, our results demonstrated that UBE2Q2, ubiquitin-conjugating enzyme, works with HUWE1 to mediate ubiquitination and degradation of target protein in kidney.

UBE2C affects breast cancer proliferation through the AKT/mTOR signaling pathway / 中华医学杂志(英文版)

BACKGROUND@#Ubiquitin-conjugating enzyme E2C (UBE2C) has been shown to be associated with the occurrence of various cancers and involved in many tumorigenic processes. This study aimed to investigate the specific molecular mechanism through which UBE2C affects breast cancer (BC) proliferation.@*METHODS@#BC-related datasets were screened according to filter criteria in the Gene Expression Omnibus (GEO) database and The Cancer Genome Atlas (TCGA) database. Then differentially expressed genes (DEGs) were identified using Venn diagram analysis. By using DEGs, we conducted the following analyses including Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), protein-protein interaction (PPI), and survival analysis, and then validated the function of the hub gene UBE2C using quantitative reverse transcription-polymerase chain reaction (RT-qPCR), cell counting kit-8 (CCK-8) assay, transwell assay, and Western blot assay.@*RESULTS@#In total, 151 DEGs were identified from the GEO and TCGA databases. The results of GO analysis demonstrated that the DEGs were significantly enriched with mitotic nuclear division, lipid droplet, and organic acid-binding. KEGG analysis showed that the peroxisome proliferators-activated receptor (PPAR) signaling pathway, regulation of lipolysis in adipocytes, and proximal tubule bicarbonate reclamation were significantly enriched in the signal transduction pathway category. The top three hub genes that resulted from the PPI network were FOXM1, UBE2C, and CDKN3. The results of survival analysis showed a close relationship between UBE2C and BC. The results of CCK-8 and transwell assays suggested that the proliferation and invasion of UBE2C knockdown cells were significantly inhibited (P < 0.050). The results of Western blot assay showed that the level of phosphorylated phosphatase and tensin homology deleted on chromosome 10 (p-PTEN) was obviously increased (P < 0.050), whereas the levels of phosphorylated protein kinase B (p-AKT), phosphorylated mammalian target of rapamycin (p-mTOR), and hypoxia-inducible factor-1 alpha (HIF-1α) were dramatically decreased (P < 0.050) in the UBE2C knockdown cell.@*CONCLUSION@#UBE2C can promote BC proliferation by activating the AKT/mTOR signaling pathway.

Overexpression of autophagy-related gene 3 promotes autophagy and inhibits salinomycin-induced apoptosis in breast cancer MCF-7 cells / 南方医科大学学报

OBJECTIVE@#To study the effects of the overexpression of autophagy-related gene 3 (ATG3) on autophagy and salinomycin-induced apoptosis in breast cancer cells and explore the underlying mechanisms.@*METHODS@#We used the lentivirus approach to establish a breast cancer cell line with stable overexpression of ATG3. Western blotting, immunofluorescence staining and transmission electron microscopy were used to analyze the effect of ATG3 overexpression on autophagy in breast cancer MCF-7 cells. Using the AKT/mTOR agonists SC79 and MHY1485, we analyzed the effect of AKT/mTOR signal pathway activation on ATG3 overexpression-induced autophagy. Western blotting and flow cytometry were used to analyze the effect of autophagy on apoptosis of the ATG3-overexpressing cells treated with salinomycin and 3-MA (an autophagy inhibitor).@*RESULTS@#In ATG3-overexpressing MCF-7 cells, ATG3 overexpression obviously promoted autophagy, inhibited the AKT/mTOR signaling pathway, significantly weakened salinomycin-induced apoptosis ( < 0.01), caused significant reduction of the levels of the pro-apoptotic proteins cleaved-caspase 3 ( < 0.01) and Bax ( < 0.05), and enhanced the expression of the anti-apoptotic protein Bcl-2 ( < 0.05). The inhibition of autophagy obviously weakened the inhibitory effect of ATG3 overexpression on salinomycin-induced apoptosis.@*CONCLUSIONS@#ATG3 overexpression promotes autophagy possibly by inhibiting the AKT/mTOR signaling pathway to decrease salinomycin-induced apoptosis in MCF-7 cells, suggesting that autophagy induction might be one of the mechanisms of drug resistance in breast cancer cells.

NEDDylation antagonizes ubiquitination of proliferating cell nuclear antigen and regulates the recruitment of polymerase η in response to oxidative DNA damage

NEDDylation has been shown to participate in the DNA damage pathway, but the substrates of neural precursor cell expressed developmentally downregulated 8 (NEDD8) and the roles of NEDDylation involved in the DNA damage response (DDR) are largely unknown. Translesion synthesis (TLS) is a damage-tolerance mechanism, in which RAD18/RAD6-mediated monoubiquitinated proliferating cell nuclear antigen (PCNA) promotes recruitment of polymerase η (polη) to bypass lesions. Here we identify PCNA as a substrate of NEDD8, and show that E3 ligase RAD18-catalyzed PCNA NEDDylation antagonizes its ubiquitination. In addition, NEDP1 acts as the deNEDDylase of PCNA, and NEDP1 deletion enhances PCNA NEDDylation but reduces its ubiquitination. In response to HO stimulation, NEDP1 disassociates from PCNA and RAD18-dependent PCNA NEDDylation increases markedly after its ubiquitination. Impairment of NEDDylation by Ubc12 knockout enhances PCNA ubiquitination and promotes PCNA-polη interaction, while up-regulation of NEDDylation by NEDD8 overexpression or NEDP1 deletion reduces the excessive accumulation of ubiquitinated PCNA, thus inhibits PCNA-polη interaction and blocks polη foci formation. Moreover, Ubc12 knockout decreases cell sensitivity to HO-induced oxidative stress, but NEDP1 deletion aggravates this sensitivity. Collectively, our study elucidates the important role of NEDDylation in the DDR as a modulator of PCNA monoubiquitination and polη recruitment.

Ubiquitin-proteasome system and sperm DNA repair: An update / 中华男科学杂志

The ubiquitin-proteasome system (UPS) is a proteasome system widely present in the human body, which is composed of ubiquitin (Ub), ubiquitin activating enzymes (E1), ubiquitin conjugating enzymes (E2), ubiquitin protein ligases (E3), 26S proteasome, and deubiquitinating enzymes (DUBs) and involved in cell cycle regulation, immune response, signal transduction, DNA repair as well as protein degradation. Sperm DNA is vulnerable to interference or damage in the progression of chromosome association and homologous recombination. Recent studies show that UPS participates in DNA repair in spermatogenesis by modulating DNA repair enzymes via ubiquitination, assisting in the identification of DNA damage sites, raising damage repair-related proteins, initiating the DNA repair pathway, maintaining chromosome stability, and ensuring the normal process of spermatogenesis.

Are 30 minutes of rest between two incremental shuttle walking tests enough for cardiovascular variables and perceived exertion to return to baseline values?

Objective: To verify whether 30 minutes of rest between two incremental shuttle walking tests (ISWT) are enough for cardiovascular variables and perceived exertion to return to baseline values in healthy subjects in a broad age range. Method: The maximal exercise capacity of 334 apparently healthy subjects (age ≥18) was evaluated using the ISWT. The test was performed twice with 30 minutes of rest in between. Heart rate (HR), arterial blood pressure (ABP), dyspnea, and leg fatigue were evaluated before and after each test. Subjects were allocated to 6 groups according to their age: G1: 18-29 years; G2: 30-39 years; G3: 40-49 years; G4: 50-59 years; G5: 60-69 years and G6: ≥70 years. Results: All groups had a good performance in the ISWT (median >90% of the predicted distance). The initial HR (HRi) of the second ISWT was higher than the first ISWT in the total sample (p<0.0001), as well as in all groups (p<0.0001). No difference was observed in the behavior of ABP (systolic and diastolic) and dyspnea between the two tests, but this difference occurred for leg fatigue (greater before the second ISWT) in G1 (p<0.05). Most subjects (58%) performed better in the second test. Conclusion: 30 minutes of rest between two ISWTs are not enough for all cardiovascular variables and perceived exertion to return to baseline values. However, this period appears to be sufficient for blood pressure and performance to recover in most subjects. .

UBE2B gene and male infertility: an update / 中华男科学杂志

Male infertility is a worldwide problem, and about 15% of the cases are associated with spermatogenesis-related gene mutation. The mammalian gene UBE2B is the homolog of the RAD6 gene of yeast, belonging to the ubiquitin proteasome system and playing an important role in spermatogenesis. Mice lacking the UBE2B gene are infertile, with reduced sperm motility, increased morphologically abnormal sperm, and inhibited meiosis of spermatogonia. Accumulated evidence shows that UBE2B gene mutants and single nucleotide polymorphisms are associated with male infertility. This article reviews the relation between the UBE2B gene and male infertility, offering some theoretical evidence for the diagnosis and treatment of male infertility.

Expression of UBE2Q2, a putative member of the ubiquitin-conjugating enzyme family in pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia [ALL] is a cancer of the white blood cells most commonly found in childhood with a peak incidence at 2-5 years of age. The ubiquitin degradation pathway facilitates degradation of damaged proteins and regulates the growth and stress response. This pathway is activated in various cancers, including ALL. It has been previously reported that the newly characterized human gene UBE2Q2, a putative member of the ubiquitin-conjugating enzyme family, is over-expressed in the tumor mass and invasive epithelium in head and neck squamous cell carcinoma and breast cancer. Here, we have used quantitative reverse transcriptase polymerase chain reaction [RT-PCR] to assess expression of the UBE2Q2 gene in bone marrow samples of 20 children with ALL. Whole blood samples of 20 normal children were used as control specimens. RT-PCR revealed the expression of UBE2Q2 mRNA in 80% of the bone marrow samples from ALL patients as well as in 85% of leukemic normal peripheral blood cells. According to the results of quantitative RT-PCR, the levels of UBE2Q2 mRNA expression in the bone marrow cells of 11 out of the 20 children with ALL [55%] were significantly higher [> 2-47 fold] than those in blood cells of normal children. Our data suggest that the newly characterized human gene, UBE2Q2, may have implications for the pathogenesis of ALL and could be used for molecular diagnosis purposes in the future

Ubc9 expression predicts chemoresistance in breast cancer / 癌症

Ubiquitin-conjugating enzyme 9 (Ubc9), the sole conjugating enzyme for sumoylation, regulates protein function and plays an important role in tumorigenesis. Whether Ubc9 is involved in the chemoresistance of breast cancer remains unknown. In this study, we aimed to evaluate the contribution of Ubc9 in the chemoresistance of breast cancer. Immunohistochemistry (IHC) was used to examine the expression level of Ubc9. Chi-square test, Wilcoxon test, and one-way ANOVA were applied to analyze the relationship between Ubc9 expression, clinicopathologic features, and clinical response to neoadjuvant chemotherapy. The significance of variables for survival was analyzed by the Cox proportional hazards model in a multivariate analysis. Kaplan-Meier survival curves were plotted and log-rank test was performed. The proportion of Ubc9-positive cells was higher in invasive ductal carcinoma than in normal breast tissues [(48.48 ± 17.94)% vs. (5.82 ± 2.80)%, P < 0.001]. High Ubc9 expression was associated with poor differentiation (Χ² = 6.538, P = 0.038), larger tumor size (Χ² = 4.701, P = 0.030), advanced clinical stage (Χ² = 4.651, P = 0.031), lymph node metastasis (Χ² = 9.913, P = 0.010), basal-like phenotype (Χ² = 8.660, P = 0.034), and poor clinical response to neoadjuvant chemotherapy (Χ² = 11.09, P = 0.001). The expected 6-year cumulative disease-free survival rate was 87.32% in patients with low Ubc9 expression compared to 68.78% in those with high Ubc9 expression (Χ² = 4.289, P = 0.038). These data indicate that high Ubc9 expression correlates with poor response to chemotherapy and poor clinical prognosis.

UbcH10 expression in hepatocellular carcinoma and its clinicopathological significance / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate UbcH10 expression in hepatocellular carcinoma and explore its clinicopathological implications.</p><p><b>METHODS</b>We detected UbcH10 mRNA expression using RT-PCR in normal liver cell line, cancer cell lines, surgically removed hepatocellular carcinoma tissue and corresponding adjacent non-tumor tissue and evaluated the clinicopathological significance of UbcH10. Immunohistochemistry was performed to investigate UbcH10 protein expression in hepatocellular carcinoma tissue, the adjacent tissue, and normal liver tissue specimens.</p><p><b>RESULTS</b>Normal liver cell line L02 showed significantly lower UbcH10 mRNA expression levels than the cancer cell lines BEL-7402, Hep3B, HepG2 and SMMC-7721 (P<0.05). UbcH10 mRNA expression was also was significantly higher in hepatocellular carcinoma tissues than in the corresponding non-tumor tissues (P<0.05). Clinicopathological evaluation suggested that UbcH10 expression was associated with tumor invasion of the portal vein, tumor size, TNM staging, and tumor differentiation (P<0.05). Immunohistochemistry identified stronger UbcH10 expression in hepatocellular carcinoma tissues than in the adjacent tissues and normal liver tissues (68.6%, 28.6%, and 26.7%, respectively).</p><p><b>CONCLUSION</b>UbcH10 is over-expressed in hepatocellular carcinoma and may serve as a novel biomarker as well as a therapeutic target of hepatocellular carcinoma.</p>

Atg3-Mediated Lipidation of Atg8 Is Involved in Encystation of Acanthamoeba

Autophagy is a catabolic process involved in the degradation of a cell's own components for cell growth, development, homeostasis, and the recycling of cellular products. Autophagosome is an essential component in the protozoan parasite during differentiation and encystation. The present study identified and characterized autophagy-related protein (Atg) 3, a member of Atg8 conjugation system, in Acanthamoeba castellanii (AcAtg3). AcAtg3 encoding a 304 amino acid protein showed high similarity with the catalytic cysteine site of other E2 like enzymes of ubiquitin system. Predicted 3D structure of AcAtg3 revealed a hammer-like shape, which is the characteristic structure of E2-like enzymes. The expression level of AcAtg3 did not increase during encystation. However, the formation of mature cysts was significantly reduced in Atg3-siRNA transfected cells in which the production of Atg8-phosphatidylethanolamine conjugate was inhibited. Fluorescent microscopic analysis revealed that dispersed AcAtg3-EGFP fusion protein gathered around autophagosomal membranes during encystation. These results provide important information for understanding autophagic machinery through the lipidation reaction mediated by Atg3 in Acanthamoeba.

SUMOylation of RIG-I positively regulates the type I interferon signaling

Retinoic acid-inducible gene-I (RIG-I) functions as an intracellular pattern recognition receptor (PRR) that recognizes the 5'-triphosphate moiety of single-stranded RNA viruses to initiate the innate immune response. Previous studies have shown that Lys63-linked ubiquitylation is required for RIG-I activation and the downstream anti-viral type I interferon (IFN-I) induction. Herein we reported that, RIG-I was also modified by small ubiquitin-like modifier-1 (SUMO-1). Functional analysis showed that RIG-I SUMOylation enhanced IFN-I production through increased ubiquitylation and the interaction with its downstream adaptor molecule Cardif. Our results therefore suggested that SUMOylation might serve as an additional regulatory tier for RIG-I activation and IFN-I signaling.

Selecting functional siRNA target sites of hUBE2W based on H1-U6 dual promoter RNAi plasmid / 生物工程学报

hUBEW, a newly identified class I ubiquitin conjugating enzyme, probably plays an important role in tumorigenesis and DNA repair processes. RNA interference (RNAi) is a process in cells to degrade specific homologous mRNA by forming duplex RNA and has been developed into a powerful tool to study gene functions. In this study, the H1-U6 dual promoter RNAi plasmid was constructed and the target sequence for hUbe2w could be transcribed from both strands and form a double stranded RNA with two 5'Uridine overhangs, which closely resembles endogenous functional siRNA. The hUbe2w cDNA was amplified from reverse transcription of the 293FT total RNA by RT-PCR, and then cloned into the pGL3-Control, pCMV-myc and pDsRed-express-C1 plasmids respectively, which were selected as report vectors to detect the RNAi effects. The plasmids were co-transfected into HEK293FT cells, and then the luciferase activity and hUBE2W protein expression were measured respectively. The Resulted reduction of mRNA and protein level demonstrate that the targets of 125 and 259 could significantly inhibit the hUbe2w expression.

Novel UBE2B-associated polymorphisms in an azoospermic/oligozoospermic population / 亚洲男科学杂志(英文版)

<p><b>AIM</b>To assess whether abnormalities exist in the UBE2B gene in a population of infertile human males, and to establish biologic plausibility of any discovered mutations.</p><p><b>METHODS</b>We carried out polymerase chain reaction (PCR) amplification and sequence analysis of the 5'-untranslated region and six exons of the UBE2B gene, including flanking intronic regions, in a group of fertile and infertile men. Following the identification of a putative promoter region that contained single or dual triplet deletions within a 10-CGG repeat island, we evaluated the binding affinity of these identified polymorphisms as compared to the wild-type sequence to transcription factor SP1 using a DNA-protein gel shift assay.</p><p><b>RESULTS</b>There was a novel exonic single nucleotide polymorphism (SNP) noted in exon 4 in 5% of infertile men. In silico 3D modeling of the altered protein showed an innocuous isoleucine for valine substitution. There were no mutations noted within any of the other exons. Three novel intronic SNPs were identified within the fertile group, and seven novel intronic SNPs identified in the infertile group. The DNA-protein gel shift assay noted that both single CGG deletion and double CGG deletion bands had approximately twice the binding affinity compared to the wild-type for SP1. The negative control confirmed no non-specific protein binding.</p><p><b>CONCLUSION</b>By themselves, a single or double CGG deletion is unlikely to pose biologic significance. However, such deletions in this suspected promoter region are associated with increased binding affinity for SP1, and might represent one of several factors required for alteration of UBE2B gene expression.</p>

Generation of mouse UBE2W antibody and analysis of UBE2W expression in mouse tissues / 生物工程学报

Ubiquitin conjugating enzyme functions as the second enzyme required for protein ubiquitination and plays an important role in ubiquitin transferring and substrate specific recognition. UBE2W, a newly described member of E2 family, was formerly reported probably involving in phototransduction or retinal degeneration in Drosophila. In this study, we report that murine UBE2W harbors a typical UBC domain and is highly conserved in different vertebrate homologues. GST-tagged UBE2W was expressed in E. coli BL21 (DE3) and purified with GST affinity chromatography. Using this antigen, we generated and further separated rabbit polyclonal antibody of UBE2W, of which the activity and specificity were confirmed by immunoblotting of transiently expressed myc-UBE2W fusion protein. Wide expression of UBE2W was found in brain, muscle, heart, lung, liver, spleen, kidney and testis of mouse with the generated antibody, indicating the functional importance of this novel protein. Furthermore, the UBE2W highly expression was confined to the adult testis and was developmental stage-specific.

Characterization of the gene expression related to the process of DNA damage tolerance in Schistosoma mansoni

In the course of its complex life cycle, the parasite Schistosoma mansoni need to adapt to distinct environments, and consequently is exposed to various DNA damaging agents. The Schistosoma genome sequencing initiative has uncovered sequences from genes and transcripts related to the process of DNA damage tolerance as the enzymes UBC13, MMS2, and RAD6. In the present work, we evaluate the importance of this process in different stages of the life cycle of this parasite. The importance is evidenced by expression and phylogenetic profiles, which show the conservation of this pathway from protozoa to mammalians on evolution.

Expression profiling of UBF, a novel member of UBC family / 中国应用生理学杂志

<p><b>UNLABELLED</b>From large-scale sequence of human fetal liver cDNA library, we have obtained a full-length cDNA from an EST after further sequencing. It has been demonstrated by the alignment comparison with data base available that it is a novel member of Ubc family and got the number from GeneBank: UBF-F1 AF 294842.</p><p><b>AIM AND METHODS</b>To demonstrate its authenticity, UBF was amplified from the total RNA of human fetal liver and HL-60 cell line using RT-PCR, and the PCR products were further sequenced and compared with the original UBF sequence. To evaluate the expression level and subcellular location of UBF in human multiple tissues, in situ hybridization was carried out on the frozen section of human fetal multiple tissues and HL-60 cell line with DIG-labeled UBF cDNA probes.</p><p><b>RESULTS</b>The experimental results of RT-PCR and sequencing showed that the sequence of RT-PCR products were the same as the original UBF. The experimental results of in situ hybridization showed that UBF was expressed widely by human multiple fetal tissues and the expression level were very high in HL-60 cells.</p><p><b>CONCLUSION</b>It is suggested that the special structure of UBF is authentic, and the expression profiling research of UBF shows that UBF is expressed widely by human multiple fetal tissues and the expression level is very high in HL-60 cells, implying that UBF plays the important function in the developing tissues and leukemia cells. It is also suggested that UBF may be functionally related with the nucleic-involving cellular activities based on the results of sub-cellular localizations.</p>

Purification and Identification of Ubiquitin Binding Proteins from Erythrocytes of Patients with Dementia

OBJECTIVE: The continuous synthesis and degradation of proteins in the cell are essential for the maintenance of cellular homeostasis. Intracellular protein degradation largely occurs in the lysosome and cytoplasm. The protein degradation in the cytoplasm (ubiquitin mediated protein degradation) is distinct from the well studied lysosomal protein degradation (nonselective protein degradation) and require energy (ATP), ubiquitin and ubiquitin conjugating enzymes such as E1, E2 and E3. Dementia caused by the deposition of abnormal proteins in brain cells followed by brain cells damage are not fully understood. To better understand the possible mechanism of dementia, we attempted to purify ubiquitin conjugating enzymes (such as E1 and E2 proteins) from the blood of normal persons and patients with dementia and tested their electrophoretic mob)ility on SDS-polyacrylamide gel electrophoresis. METHOD: The E1 and E2 enzymes of the red blood cell lysate fraction from the normal person and the patients with dementia were purified from ammonium sulfate precipitatant of DEAE-cellulose eluate fraction. Following ubiquitin-sepharose column chromatography, the E1 enzyme of the normal and the patients with dementia group showed homogeneous form and various kinds of E2 isoforms were identified by the SDS-polyacrylamide gel electrophoresis. RESULTS: The E1 and E2 enzymes showed no difference on electrophoretic mobility, but the E2 isozyme containing fraction was observed to great difference between the two groups. The 44 kDa protein of E2 isozyme containing fraction was significantly increased in alcoholic dementia and clearly increased in patients with Alzheimer's disease. In addition, another 11 kDa protein was significantly increased in the patients with Alzheimer's disease, but 11 kDa protein of alcoholic dementia was similar to that of the normal person. The 44 kDa and 11 kDa proteins showed a reverse relationship between alcoholic dementia and the patients with Alzheimer's disease. These proteins seems to be different molecules from the well known studied beta-amyloid, presenilin, tau protein and apolipoprotein E (Apo E). CONCLUSIONS: These results might be useful for the elucidation of dementia and the identification of these proteins are now in progress.

Cloning and characterization of human ubiquitin binding enzyme 2 cDNA / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To clone and identify the gene encoding human ubiquitin binding enzyme 2 and study its expression pattern.</p><p><b>METHODS</b>According to the sequence of human EST, which is highly homologous to the mouse ubiquitin binding/conjugating enzyme (E2), primers were synthesized to screen the human fetal brain cDNA library. The gene was analyzed by bioinformatics technique and its expression pattern was studied by using multiple-tissue Northern blot.</p><p><b>RESULTS</b>Two cDNA clones encoding human ubiquitin conjugating enzyme have been isolated and identified. Both containing the ubiquitin conjugating domain, the 2 cDNA clones are 88% identical in amino acid sequences and splicing isoforms to each other only with an exon excised to form the short sequence. They belong to a highly conserved and widely expressed E2 enzyme family. Northern blot shows that they are expressed exclusively in adult human heart, placenta, and pancreas but no transcripts can be detected in brain, lung, liver, skeletal muscle or kidney.</p><p><b>CONCLUSIONS</b>The gene encoding human ubiquitin binding enzyme is expressed under temporal control. As a key enzyme in the degradation of proteins, ubiquitin conjugating enzymes play a central role in the expression regulation on the level of post-translation.</p>