Research progress on 26S proteasome inhibitors / 药学学报

The 26S proteasome is a 2.5 MDa complex of the protease family members and is central to a vast array of vital cellular processes including cell-cycle progression and antigen presentation. It has been proven to be a target for therapeutic agents in the treatment of cancers and autoimmune diseases. Most inhibitors are designed to target the 20S proteolytic core complex while the efforts to target the 19S regulatory particle subunits are less successful so far. This is, in part, due to the complexity of molecular architecture and poor understanding of the mechanism of this subcomplex. This review attempts to summarize the development of inhibitory molecules that target both the 20S and 19S subunits of the proteasome, especially highlight the recent progress in the proteasome structure and development of the new inhibitors.

26S proteasome regulates differentiation of human bone marrow stromal cells into neural-like cells / 中国病理生理杂志

AIM: To investigate the process of human bone marrow stromal cells (hBMSCs) differentiation into neural-like cells and to determine the role of 26S proteasome in neuronal differentiation. METHODS: Purified hBMSCs were treated with β-mercaptoethanol (β-ME) for 1 day and retinoic acid (RA) for 3 days, followed by growth factor (10 μg/L bFGF or 20 μg/L NGF) for another 3 days. Immunofluorescence was performed to detect the expression of nestin (a neural precursor cells marker), Tuj1 (a premature neuronal marker), and neurofilament (NF, a mature neuronal marker) at all stages of induced differentiation. Immunostaining and RT-PCR were used to analyze the expression of 26S proteasome during neuronal differentiation of hBMSCs. To further confirm the role of 26S proteasome in hBMSCs differentiation, cells were treated with β-ME/RA and then followed by protesome inhibitor MG132 and growth factor. Immunostaining was performed to detect NF-positive cells. RESULTS: Quantification results showed that the untreated cells were almost never positive for nestin, Tuj1 and NF. After treated with β-ME/RA, the numbers of nestin-positive cells (34.41%±1.27%) and Tuj1-positive cells (27.79%±1.27%) were increased. Notably, the numbers of NF-positive cells were significantly increased to 56.72%±2.4% after induction with β-ME/RA/GF. Immunofluorescence analysis showed that undifferentiated hBMSCs cells were weakly stained by antibody against 26S proteasome, but the numbers of cells with high-intensity of 26S proteasome were increased after treated with β-ME/RA. The RT-PCR result of 26S proteasome further confirmed that the mRNA level of the cells differentiated by β-ME/RA (1.33), as well as by β-ME/RA/GF (1.77), was significantly increased compared to the undifferentiated cells. Moreover, hBMSCs incubated with protesome inhibitor MG132 significantly decreased the numbers of NF-positive cells (37.59%±1.52%). CONCLUSION: After induction with β-ME/RA/GF, hBMSCs can be differentiated into neural-like cells, which is concomitant with the increase in 26S proteasome expression. Inhibitor of 26S protesome prevents hBMSCs differentiation, suggesting that 26S proteasome may be involved in the differentiation of hBMSCs into neural-like cells.

The Changes in Contractile Protein Degradation and 26S Proteasome Activity of Skeletal Muscle in Rat after an Acute Exercise / 中国运动医学杂志

Objective To explore the effects of an acute exercise on the contractile protein degradation and 26S proteasome activity in skeletal muscle.Methods Thirty-six male Sprague-Dawley rats were randomly divided into 6 groups,each group consisted of 6 rats.They were killed respectively at rest,immediately after half an hour of exercise(running on the treadmill at 25m/min,5% grade),and 1 hour,2h and 6h after one hour exercise.The 3-methylhistidine(3-MH)content,26S proteasome activity and C2 subunit mRNA expression in rat gastrocnemius muscle were detected.Resuits(1)3-MH content increased immediately and 6 hours after exercise,and reached its peak level immediately after half an hour of exercise(P<0.01).(2)26S proteasome activity increased immediately after half an hour of exercise and 6 hours after exercise(P<0.05).(3)Expression of 26S proteasome C2 subunit mRNA Was lower than baseline during and after exercise,but increased sharply 6 hours after exercise(P<0.01).Conclusion The increase in 26S proteasome activity regulated by subunits gene after exercise could enhance skeletal muscle contractile protein degradation

The Progress on The Ubiquitin 26S Proteasome Pathway in Plants / 中国生物工程杂志

Selective protein degradation by the ubiquitin 26S proteasome pathway has emerged as a key regulatory mechanism in a wide variety of cellular processes.The ubiquitin/26S proteosome pathway mainly consists of ubiquitin activating enzyme(E1),ubiquitin conjugating enzyme(E2),ubiquitin protein ligase(E3),and 26S proteasome.In an ATP-dependent reaction,uibquitin(Ub) is conjugated to E1,the activated Ub is then transferred to an E2.Finally,the Ub-E2 intermediate delivers the Ub to the target protein by E3 recognition.Polyubiquinated proteins are eventually degraded by the 26S proteasome.In plants,regulated protein degradation by /26S proteasome pathway contributes significantly to development by affecting a wide range of progress,including hormone signaling,photomorphogenesis,self-incompatibility and cell cycle.The recent progress towards understanding the role of the Ub/26S proteasome pathway during plant development was reviewed.

The effect of enteral feeding and parenteral nutrition on the 26 S proteasome in skeletal muscle of the severely scalding rats / 肠外与肠内营养

Objectives:To compare the effect of defferent routes of nutritional support on the 26 S proteasome. Methods:The means of immuno precipitation deduction,ELISA and fluore photomction were used to test the change of activities,contents of the 26 S proteasome and the rate of protein degradation in skeletal muscle of scalding rats with the animal model of enteral feeding and parenteral nutrition. Results:Compared with parenteral nutrition,enteral feeding could markedly reduce the activity and content of the 26 S proteasome,and the release of tyrosine was also lowered. Conclusions:The early enteral feeding can distinctly inhibit the system of 26 S proteasome,and reduce the protein degradation in skeletal muscle in bruned rats.

Effects of TNF? on 26S proteasome and 19S regulator in skeletal muscle of the severely scalded rats / 第三军医大学学报

Objective To explore the mechanism of negative nitrogen balance in the treatment after burns. Methods The means of immuno precipitation deduction and ELISA were used to test the activities and contents of 26S proteasome and 19S regulator in skeletal muscle of rats inflicted with 30%TBSAⅢ burns. Results TNF? markedly raised the activities and contents of 26S proteasome and 19S regulator in skeletal muscle after scalding. Conclusion TNF? activates the 26S proteasome system in skeletal muscle, thus it enhances the degradation of protein, which is associated with the development of negative nitrogen balance following scalding.

CHANGES IN ACTIVITY OF THE 26S PROTEASOME AND 19S REGULATOR IN SKELETAL MUSCLE OF SEVERELY SCALDED RATS / 解放军医学杂志

To elucidate the mechanism of negative nitrogen balance after burns, immuno precipitation deduction was used to observe the changes in the activity of 26S proteasome and 19S regulator in skeletal muscle of rats inflicted with 30%TBSAⅢ o burns. The protease activity, ATPase activity of 26S proteasome,as well as 19S regulator in skeletal muscle of rats were markedly enhanced on the second day after scald. It is suggested that burn injury could activate the 26S proteasome in skeletal muscle, in turn enhance the degradation of protein , which is associated with negative nitrogen balance following scald