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The abnormality of ubiquitin proteasome pathway is an important factor leading to the imbalance of protein homeostasis. In this process, the deubiquitinase responsible for removing the ubiquitin chain of protein substrate is very important. Its abnormal activity or expression can cause the functional changes of key oncogenic/tumor suppressor proteins, which directly or indirectly lead to the occurrence, development and malignant evolution of tumors. Based on this, the discovery and research of small molecule inhibitors targeting deubiquitinases have become a hot field of anti-tumor candidate drugs. This review will focus on the regulatory effect and mechanism of ubiquitin proteasome pathway, especially deubiquitinase on tumor, introduce the application of deubiquitinase small molecule inhibitors in tumor treatment, and discuss the research status and latest progress of small molecule inhibitors, so as to provide ideas for the research of new anti-tumor strategies based on deubiquitinase.
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Methylmercury is an environmental pollutant that causes neurotoxicity. Recent studies have reported that the ubiquitin-proteasome system is involved in defense against methylmercury toxicity through the degradation of proteins synthesizing the pyruvate. Mitochondrial accumulation of pyruvate can enhance methylmercury toxicity. In addition, methylmercury exposure induces several immune-related chemokines, specifically in the brain, and may cause neurotoxicity. This summary highlights several molecular mechanisms of methylmercury-induced neurotoxicity.
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Animals , Humans , Mice , Rats , Chemokines , Metabolism , Methylmercury Compounds , Toxicity , Neurotoxins , Toxicity , Proteolysis , Saccharomyces cerevisiaeABSTRACT
OBJECTIVE: To explore the mechanism of ubiquitin-proteasome pathway(UPP) in the degradation of hyperphosphorylated tau protein in aluminum-induced mouse neuroblastoma N2 a cells. METHODS: N2 a cells in logarithmic growth period were randomly divided into control group and MG132 group. Cells in control group were exposed to concentrations of 0 or 1 mmol/L aluminum chloride for 24 hours. Cells in MG132 group were pretreated with MG132 at a concentration of 5 μmol/L for 6 hours, then exposed to concentrations of 0 or 1 mmol/L aluminum chloride for 24 hours. After exposure, the cells were collected. Western blotting was used to detect the relative expression of tau-5, P-tau181, P-tau231, P-tau262, P-tau396, heat shock protein 70(Hsp70) and carboxyl terminus of the Hsp70-interacting protein(CHIP). The ubiquitin relative expression was detected by enzyme-linked immunosorbent assay. RESULTS: The results of factorial analysis showed that the relative expression of tau-5, P-tau231, P-tau262, P-tau396, CHIP, Hsp70 and ubiquitin in N2 a cells were statistically significant in the main effect and interaction effect of aluminum chloride and MG132 treatment(P<0.05). Both in the control group and MG132 group, the relative expression of tau-5, P-tau231, P-tau262, P-tau396, CHIP, Hsp70 and ubiquitin in N2 a cells exposed to 1 mmol/L aluminum chloride increased(P<0.05) when compared with the N2 a cells without exposed to aluminum chloride. No matter aluminum chloride exposed or not, the relative expression of tau-5, P-tau231, P-tau262, P-tau396, CHIP, Hsp70 and ubiquitin in N2 a cells of MG132 group was higher than that of control group(P<0.05). CONCLUSION: UPP is involved in the regulation of hyperphosphorylated tau protein by proteasome degradation in aluminum-induced N2 a cells. UPP mainly regulates P-tau231, P-tau262, and P-tau396 sites. CHIP and Hsp70 played an important role in the UPP pathway.
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The ubiquitin-proteasome pathway is responsible for the degradation of most cellular proteins in eukaryotes.It regulates almost all cellular activities, including cell proliferation, differentiation, apoptosis, gene transcription, and DNA repair.The dysfunction of the ubiquitin-proteasome pathway is associated with the pathogenesis of numerous human diseases, including cancer and neurodegenerative diseases.The marketed proteasome inhibitors have been successfully used to treat multiple myeloma and mantle cell lymphoma.Furthermore, novel inhibitors against the components of the ubiquitin-proteasome pathway are under developed and exhibit promising therapeutic effects in vivo.This paper will briefly introduce the progress on the drug discovery related to the ubiquitin-proteasome pathway.
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Objective:To investigate the effect of HSPC 238 overexpression or low expression on the regulation of the target protein ( HMOX1, MT2A, UBB, RPS27a ) and the regulation pathways.Methods: To construct the interference vector and overexpression vector of HSPC238 respectively,transfected the HEPG2 cell lines by the liposome method,detect the expression of mRNA and protein of the HSPC 238 and the target proteins by the RT-PCR and Western blot , further to transfer the overexpression plasmids of the target proteins into the HEPG 2 cell lines which had been transfected with interference vector and overexpression vector of HSPC238,the experimental group cell lines were treated with proteasome inhibitor MG 132,to purify the target proteins with nickel column,do immunoblotting with HSPC238 to detect the accumulation situation of the target proteins.Results: The HMOX1,MT2A, RPS27a were downregulated obviously when the HSPC 238 was interfered exogenous;and the MT2A,UBB,RPS27a were up-regulated after the HSPC238 overexpressed.The overexpression plasmid of target proteins were transfected into the HEPG 2 cell lines which have been transfected with interference vector and overexpression vector of HSPC 238 ,compared with the control group ,the target protein band in the experimental group was significantly increased after treatment with the proteasome inhibitor MG 132.Conclusion:The HSPC238 overexpression can upregulate the expression of MT 2A,UBB and RPS27a,and interfering HSPC238 can downregulate the expression of HMOX1,MT2A and RPS27a;the HSPC238 target protein may play a regulatory role through the UPP pathway;the HSPC238 may play a regulatory role on the target proteins through the UPP pathway.
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Diabetic retinopathy (DR) is one of the common and serious diabetic complications,with a complex nosogenesis.Studies have shown that transforming growth factor-β (TGF-β) participates in the occurrence and development of DR,and Smads protein is able to mediate and activate TGF-β/Smads signal transduction pathway and further involves in the pathogenesis of DR.Smurf is one of the ubiquitin ligases in ubiquitin-proteasome pathway,and it is clarified to regulate TGF-β/Smads signal transduction pathway degradation.At present,the study on the relationship between TGF-β/Smads pathway and DR has made great progress.The role of ubiquitin-proteasome pathway regulating TGF-β/Smads signal transduction pathway in DR is reviewed in this article.
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Hypermetabolism syndrome,especially in skeletal muscles,is exceedingly common in septic patients.Many studies suggest that the activity of ubiquitin-proteasome pathway is a vital procedure for hypermetabolism of skeletal muscles of septic patients and its activation can be influenced by a variety of factors,such as proinflammatory cytokine and glucocorticoid,etc.Evidences indicate that insulin has played an important role in opsonizing the activation of ubiquitin-proteasome pathway.This paper reviews the regulation effect of insulin to the hypermetabolism of the skeletal muscles of septic patients through ubiquitin-proteasome pathway.
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Objective To investigate the dynamic expression of the 20S proteasome in peripheral blood mononuclear cells (PBMCs) of type 2 diabetic patients without vascular complications. Methods PBMCs were prepared from 30 type 2 diabetic patients and 30 nondiabetic controls. The general indexes including weight, height and blood pressure were recorded. Fasting plasma glucose, fasting plasma insulin and glycosylated hemoglobin were measured. The protein level of the 20S proteasome was measured by Western blotting. The mRNA expression levels of the 20S proteasome β1, β2 and β5 subunits were detected by real-time PCR. Results Compared with that in the nondiabetic controls, the protein level of the 20S proteasome was significantly increased in the diabetic patients and was positively associated with glycosylated hemoglobin. Conclusion Type 2 diabetic patients without vascular complications have an increased 20S proteasome expression, the significance of which needs to be explored by further study.
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To explore the effect of high glucose on the NF-κB/IκB signal pathway in cultured rat glomerular mesangial cells. The results showed that high glucose increased the degradation of IκB-α and the translocation to nucleus of NF-κB. These changes could be reverted mostly by MG132, a proteasome inhibitor. It suggests that the activation of the NF-κB signal pathway by high glucose concentration may probably be via the ubiquitin-proteasome pathway.
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Objective: To investigate the dynamic expression of the 20S proteasome in peripheral blood mononuclear cells (PBMCs) of type 2 diabetic patients without vascular complications. Methods: PBMCs were prepared from 30 type 2 diabetic patients and 30 nondiabetic controls. The general indexes including weight, height and blood pressure were recorded. Fasting plasma glucose, fasting plasma insulin and glycosylated hemoglobin were measured. The protein level of the 20S proteasome was measured by Western blotting. The mRNA expression levels of the 20S proteasome β1, β2 and β5 submits were detected by real-time PCR. Results: Compared with that in the nondiabetic controls, the protein level of the 20S proteasome was significantly increased in the diabetic patients and was positively associated with glycosylated hemoglobin. Conclusion: Type 2 diabetic patients without vascular complications have an increased 20S proteasome expression, the significance of which needs to be explored by further study.
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Objective To explore the role of ubiquitin-proteasome pathway for the gelsolin protein degradation in pancreatic cancer.Methods Pancreatic cancer cell lines BxPC-3 and PANC-1 were first treated with specific 26s proteasome inhibitor lactacystin.Immunoblots of cell lysates were probed for gelsolin expression.To determine whether gelsolin was conjugated to ubiquitin,proteins extracted from the cells with or without lactacystin were immunoprecipitated with anti-gelsolin antibody,followed by Western blot analysis.Results The expression of gelsolin protein increased obviously after treatment with lactacystin in BxPC-3 cells for 12 h.Using anti-gelsolin antibody to immunoprecipitate gelsolin protein and followed by Western blot using anti-ubiquitin monoclonal antibody,it was found that inhibition of proteasome pathway by lactacystin resulted in accumulation of ubiquitylated forms of gelsolin protein.In PANC-1 cell line,there was no significant changes of gelsolin after treatment with lactacystin.Conclusion Ubiquitin-proteasome dependent degradation may be an important regulatory mechanism for gelsolin down-regulation in pancreatic cancer cells.
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Hepatocellular carcinoma is one of the largest causes of cancer-related deaths worldwide for which there are very limited effective treatment options.The ubiquitin-proteasome pathway(UPP) has rapidly become acknowledged as both critical mechanism for cellular biological function and a latent target of regulation of cancer-related disease.This review focus on the role of ubiquitin-proteasome pathway in hepatocellular carcinoma and its correlation factors(HBV、P27、NF-?B,et al),in order to find novel therapeutic interventions against the genesis and development of hepatocellular carcinoma.
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Aim To study the effect of proteasome inhibitor MG132 on expression of Caspase-3 and UPP associated genes in the apoptosis of human hepatocelluar cancer cells.Methods HepG2 cells were treated with MG132 (2,5,10 ?mol?L -1) for 24 h. The apoptotic cells were determined with flow cytometric analysis. The levels of E1, E2, E3 and Caspase-3 mRNA expression were detected with RT-PCR. Caspase-3 protein expression was detected with immunohistochemistry. Results The results showed that the increase of the degree of HepG2 cell apoptosis was concentrationly dependent. RT-PCR showed that E1, E2 and E3 gene expressions were decreased in the treatment group. MG132 down-regulated the gene expression of E1, E2, E3 and up-regulated the gene/protein expression of Caspase-3. Conclusion Proteasome inhibitor MG132 may induce HepG2 cells apoptosis by inhibitting UPP activity,up-regulating the gene/protein expression of Caspase-3.
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Objective To investigate the clinical significance of P27~ KIP1 and S-phase kinase-associated protein 2 (SKP2) expression in human gastric carcinoma. Methods The expression of P27~ KIP1 and SKP2 was determined by SP immunohistochemical method in 69 specimens of gastric carcinoma. Results The positive rates of P27~ KIP1 and SKP2 expression were 46.38% and 33.33%, respectively. The positive rate of P27~ KIP1 expression in gastric carcinoma decreased with the poor differentiation,deep invasion and progression of pathological grade (P0.05). There was a negative correlation between the P27~ KIP1 and SKP2 expression(P
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The progressive loss of skeletal muscle protein observed in cancer cachexia may have a negative impact on both the quality of life and the survival time of patients. In recent years, accumulating evidences suggest that the ATP ubiquitin proteasome pathway may be crucial in muscle cachexia. The review is mainly about the role of the ATP ubiquitin proteasome pathway in the degration of skeletal muscle protein during cancer cachexia.
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Objective To explore the extent of lung injury induced by hyperoxia,and the activity of ubiquitin-proteasome pathway(UPP) in pathophysiological progress of lung tissue in early stages.Methods Adopted completely random design,20 SD rats were divided into hyperoxia group and air control group.For the air control group,the oxygen concentration exiting the cages was analyzed with oxygen monitor and oxygen concentration remained at 210 mL/L for 72 hours;while in the hyperoxia group,the condition changed into high-density oxygen(950 mL/L) for 72 hours to estimate the hyperoxia lung injury in rats model.The contents linked morphology as pathological classification in gross finding,pathological score of lung injury and the index of pneumonedema-the ratio of moist to dry weight of lungs were mea-sured.The expressions of ubiquitin protein and the activity of proteasome 20 S and the active statement of ubiquitin-proteasome pathway were detected by immunohistochemistry and Western blot methods.Results 1.The hyperoxia lung injury rat model was successfully duplicated.2.In hyperoxia group,pulmonary edema with increased ratio of moist to dry weight of lungs could be found(P=0).3.Macroscopic observation: bright red and full-stacked lung tissue,foliated or local hemorrhage on the surface,but little pleural effusion was observed in hyperoxia group.There was statistical significance of pathological classification in gross finding between hyperoxia group and air control group(P=0.005).Light microscope observation:swelled alveolar epithelium,widened alveoli wall,capillary engorgement and telangiectasis,obvious edema in interstitial tissue of pulmonary aveolus and alveolar space,increased inflammatory cells were observed in hyperoxia group.The findings of pathological score of lung injury indicated more serious injure than control group(P=0).4.The increased expression of ubiquitin protein in lung tissue was discoved by using immunohistochemistry and Western blot findings after hyperoxia exposure 72 hours.(P=0).5.The acti-vity of proteasomes 20 S in hyperoxia group was higher than that in control group(P=0).Conclusions The mainly pathological changes of lung are generated through hyperoxic exposure for 72 hours,including alveolar epithelial cell and vascular endothelial cell injury diffusely,inflammatory cell infiltration and pulmonary edema.Active the ubiquitin-proteasome pathway is connected with the pathophysiological process of lung injury in the initial stages of hyperoxia-exposure.
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AIM:To observe the expression of Smad7 and Smad ubiquition regulatory factor-Smurf2 in rat glomerular mesangial cells (GMC) stimulated by the high concentration of glucose,and to investigate the effect of the ubiquition on Smad signaling by adding MG132 as a proteasome differential inhibitor. METHODS:Cultured rat GMC were divided into normal group (the concentration of glucose:5.6 mmol/L),high glucose group (20 mmol/L,30 mmol/L,respectively),therapy group (30 mmol/L glucose with MG132). The expressions of Smurf2 and Smad7 in each group were measured by indirect immunofluorescence and laser scanning confocal microscope. RESULTS:(1) The expression of Smurf2 in GMC in normal group was weak (25.93?3.35) whereas the expression of Smad7 was strong (64.09?7.43). (2) The expression of Smurf2 in high glucose group was stronger than that in normal group (P
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Aim To study the effect of proteasome inhibitor MG132 on the expression of caspase-3 and apoptosis in cultured human umbilical vein endothelial cells.Methods Human umbilical vein endothelial cells was treated with MG132 (2,5 ?mol?L~(-1)) for 24 h. The apoptotic cells were determined by DNA fragment analysis and flow cytometric analysis. The level of caspase-3 mRNA was quantified by reverse transcription-polymerase chain reaction (RT-PCR). The protein contents of caspase-3 were analyzed by immunocytochemistry.Results The results showed that the increase of the degree of human umbilical vein endothelial cells apoptosis was concentration dependent. MG132 could up-regulate the gene/protein expression of caspase-3.Conclusions The results implicated that proteasome inhibitor MG132 induced human umbilical vein endothelial cells apoptosis by accumulation of caspase-3.