Protein ubiquitination is one of the most important and widely exist protein post-translational modifications in eukaryotic cells, which takes the ubiquitin and ubiquitin chains as signal molecules to covalently modify other protein substrates. It plays an important roles in the control of almost all of the life processes, including gene transcription and translation, signal transduction and cell-cycle progression, besides classical 26S protesome degradation pathway. Varied modification sites in the same substrates as well as different types of ubiquitin linkages in the same modification sites contain different structural information, which conduct different signal or even determine the fate of the protein substrates in the cell. Any abnormalities in ubiquitin chain formation or its modification process may cause severe problem in maintaining the balance of intracellular environment and finally result in serious health problem of human being. In this review, we discussed the discovery, genetic characteristics and the crystal structure of the ubiquitin. We also emphasized the recent progresses of the assembly processes, structure and their biological function of ubiquitin chains. The relationship between the disregulation and related human diseases has also been discussed. These progress will shed light on the complexity of proteome, which may also provide tools in the new drug research and development processes.
Humans ; Proteome ; Ubiquitin ; chemistry ; Ubiquitination

As the major pathway mediating specific protein degradation in eukaryotes, ubiquitin-proteasome system (UPS) is involved in various physiological and pathological processes such as cell cycle regulation, immune response, signal transduction and DNA-repair. Deubiquitinases (DUB) maintain the balance of UPS and related physiological processes via reversibly removing ubiquitin from the covalently modified protein substrates, which have been implicated in various disease processes in case of their imbalance expression. Because DUB plays critical regulating roles in the UPS pathway, they may be also the ideal drug targets for severe and intractable human diseases, such as cancer and neurodegenerative disease. With the rapid development of proteomic technology, systematical investigation of specific substrates and interacting proteins of varied DUB via mass spectrometry approach may shed light on these DUB's biological function and regulating roles in the physiological and pathogenic states. In this review, we briefly introduce the characteristics of DUB and summarize the recent application and progresses of proteomics in DUB research.
Humans ; Mass Spectrometry ; Proteasome Endopeptidase Complex ; metabolism ; Proteomics ; Signal Transduction ; Ubiquitin ; metabolism ; Ubiquitin-Specific Proteases ; metabolism

Objective:To analyze the mediating effect of work-occupation fit between occupational stress and anxiety symptoms in medical staff.Methods:Convenience sampling method was adopted to select participants of one general hospital and three specialized hospitals as respondents for a questionnaire survey in Henan Province from October 2020 to January 2021. A total of 2050 medical staff were investigated, and 1988 valid questionnaires were collected, and the effective rate of the questionnaire was 97.0% (1988/2050) . The "Depression-Anxiety-Stress Scale" and "Worker-Occupation Fit Inventory" were used to evaluate the occupational stress, anxiety symptoms and worker-occupation fit level of medical staff, and the mediation effect of work-occupation fit on the relationship between occupational stress and anxiety symptoms was analyzed using a mediating effect model.Results:The average age of the 1988 medical staff was (32.7±7.8) years old, the positive detection rates of occupational stress and anxiety symptoms were 42.5% (845/1988) and 56.7% (1127/1988) , respectively. Anxiety symptoms of medical staff were positively correlated with occupational stress, negatively correlated with worker-occupation fit ( r=0.831, -0.364, P<0.001) , work-occupation fit was negatively correlated with occupational stress ( r=-0.259, P<0.001) . The results of the mediation effect analysis showed that occupational stress had a direct effect on anxiety symptoms ( β=0.677, BCa 95% CI: 0.648-0.707) , and worker-occupation fit ( β=0.047, BCa 95% CI: 0.039-0.056) , characteristic fit ( β=0.089, BCa 95% CI: 0.074-0.104) , need-supply fit ( β=0.075, BCa 95% CI: 0.062-0.089) , and ability-demand fit ( β=0.035, BCa 95% CI: 0.026-0.044) mediated the association between occupational stress and anxiety symptoms in medical staff, with the mediating effect as a percentage of 6.5%, 12.3%, 10.3%, and 4.8%, respectively. Conclusion:Worker-occupation fit has a mediating effect between occupational stress and anxiety symptoms in medical staff, but mainly direct effect.

Objective:To analyze the mediating effect of work-occupation fit between occupational stress and anxiety symptoms in medical staff.Methods:Convenience sampling method was adopted to select participants of one general hospital and three specialized hospitals as respondents for a questionnaire survey in Henan Province from October 2020 to January 2021. A total of 2050 medical staff were investigated, and 1988 valid questionnaires were collected, and the effective rate of the questionnaire was 97.0% (1988/2050) . The "Depression-Anxiety-Stress Scale" and "Worker-Occupation Fit Inventory" were used to evaluate the occupational stress, anxiety symptoms and worker-occupation fit level of medical staff, and the mediation effect of work-occupation fit on the relationship between occupational stress and anxiety symptoms was analyzed using a mediating effect model.Results:The average age of the 1988 medical staff was (32.7±7.8) years old, the positive detection rates of occupational stress and anxiety symptoms were 42.5% (845/1988) and 56.7% (1127/1988) , respectively. Anxiety symptoms of medical staff were positively correlated with occupational stress, negatively correlated with worker-occupation fit ( r=0.831, -0.364, P<0.001) , work-occupation fit was negatively correlated with occupational stress ( r=-0.259, P<0.001) . The results of the mediation effect analysis showed that occupational stress had a direct effect on anxiety symptoms ( β=0.677, BCa 95% CI: 0.648-0.707) , and worker-occupation fit ( β=0.047, BCa 95% CI: 0.039-0.056) , characteristic fit ( β=0.089, BCa 95% CI: 0.074-0.104) , need-supply fit ( β=0.075, BCa 95% CI: 0.062-0.089) , and ability-demand fit ( β=0.035, BCa 95% CI: 0.026-0.044) mediated the association between occupational stress and anxiety symptoms in medical staff, with the mediating effect as a percentage of 6.5%, 12.3%, 10.3%, and 4.8%, respectively. Conclusion:Worker-occupation fit has a mediating effect between occupational stress and anxiety symptoms in medical staff, but mainly direct effect.

Objective: To establish colorectal cancer LoVo and SW620 cell lines that stably interfere with the expression of LINC01224, and to explore the effect of down-regulating the expression of LINC01224 on cell apoptosis. Methods: The GEPIA2 database was used to analyze the expression of LINC01224 in colorectal cancer tissues; qPCR method was used to detect the expression of LINC01224 in 10 human colorectal cancer cells. Three different LINC01224 siRNAs were respectively transfected into human colorectal cancer LoVo cells, and the LINC01224 shRNA lentiviral vector was constructed with the siRNA sequence with the most obvious inhibitory effect of LINC01224 expression. Recombinant lentiviral particles were packaged in HEK293 T cells and then infected with LoVo and SW620 cells. After selection by puromycin, the monoclonal cells that stably interfere with LINC01224 were obtained by limiting dilution method. MTS method detects cell proliferation ability, and flow cytometry detects cell apoptosis rate. Results: The expression of LINC01224 in colorectal cancer tissues was higher than that in normal colorectal tissues, and its expression in 10 types of colorectal cancer cells was also higher than that in normal colorectal epithelial cells HCOEPic. The inhibition rate of siRNA-3 on the expression of LINC01224 in LoVo cells was higher than that of siRNA-1 and siRNA-2. Therefore, siRNA-3 was chosen to design LINC01224 shRNA.Compared with the control group(sh-NC group), the expression level of LINC01224 in the LoVo and SW620 cells of the stable interference LINC01224 group(sh-LINC01224 group) was reduced(P<0.01), and the cell growth rate was slowed down(P<0.01), the rate of apoptosis also increased(P<0.01). Conclusion The shRNA lentiviral interference vector of LINC01224 is successfully constructed, which can stably infect LoVo and SW620 cells, down-regulate the expression of LINC01224 and induce cell apoptosis.

Ubiquitination is one of the reversible protein post-translational modifications, in which ubiquitin molecules bind to the target protein in a cascade reaction of ubiquitin activating enzymes, ubiquitin conjugating enzymes, and ubiquitin ligases. The deubiquitinating enzymes (DUBs) remove ubiquitin residues from the substrates, which play key roles in the formation of mature ubiquitin, the removal and trimming of ubiquitin chains, as well as the recycling of free ubiquitin chains. Ubp14, a member of the ubiquitin specific proteases family in Saccharomyces cerevisiae, is mainly responsible for the recycling of intracellular free ubiquitin chains. To investigate its global biological function, a ubp14∆ mutant was constructed by homologous recombination technique. The growth rate of ubp14∆ mutant was lower than that of the wild-type (WT) strain. Using stable isotope labeling by amino acids in cell culture (SILAC) combined with deep coverage proteomics analysis, the differentially expressed proteins of ubp14∆ mutant relative to the wild-type strain were systematically analyzed. A total of 3 685 proteins were identified in this study, and 109 differentially expressed proteins were filtered out by statistical analysis. Gene ontology analysis found that differentially expressed proteins caused by Ubp14 loss were mainly involved in amino acid metabolism, REDOX, heat shock stress and etc, which shed light on the broad biological function of this DUB. This study provides highly reliable proteomic data for further exploring the biological functions of the deubiquitination enzyme Ubp14, and further understanding the relationship between the free ubiquitin homeostasis and biological process regulation.
Saccharomyces cerevisiae/metabolism* ; Proteomics ; Endopeptidases/metabolism* ; Ubiquitin/metabolism* ; Ubiquitination ; Proteins/metabolism* ; Deubiquitinating Enzymes/metabolism* ; Biological Phenomena