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Linear ubiquitination plays an important role in tumor and the immune system. Linear ubiq- uitin chain assembly complex ( LUBAC) is the only known ubiquitin ligase that can catalyze the synthesis of linear ubiquitin chains. We found that ubiquitin ligase ariadne homolog 2 ( ARIH2) was a new interacting protein of LUBAC, and ARIH2 inhibited the level of linear ubiquitination of substrates by LUBAC. We further demonstrated that ARIH2 interacted with HOIP by Co-IP experiment, and that HOIP interacted with ARIH2 through the ZF-NZF ( zinc finger-Npl4-Zinc finger) domain by GST pull-down experiments. Moreover, we showed that LUBAC could not modify ARIH2 by linear ubiquitination; On the contrary, ARIH2 inhibited the linear ubiquitination level of LUBAC substrates. The mechanism may be that ARIH2 affects the ubiquitination level of SHANK-associated RH domain interacting protein ( SHARP- IN ), thereby affecting the enzyme activity of LUBAC, which leads to the weakening of the linear ubiquit- ination level of LUBAC to the substrate.
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Postnatal skeletal growth and bone remodeling are highly coordinated processes that are primarily mediated by bone formation and bone resorption. The imbalance in bone formation relative to bone resorption will result in the net bone loss that results in changes of bone microenvironment and increased fragility, leading to diseases such as osteoporosis and bone fracture. Bone formation is mediated by osteoblasts, which mainly derived from mesenchymal stem cells (MSCs). Bone formation process is regulated by multiple signal pathways. It has been found that Wnt/ β-catenin, BMP / Smads, MAPK and other pathways are involved in the regulation of osteoblast differentiation and bone formation. In addition, some signaling related molecules may also contribute to the number increase of osteoblasts and enhanced vascularization, such as growth factors FGF, PDGF, and VEGF. These factors have been regarded as targets to promote bone formation, therefore it is important to understand their underlying molecular mechanisms. This review summarizes the latest research progress on regulatory mechanisms and clinical translational application about the above pathways on promoting bone formation, mesenchymal stem cells growth and differentiation, aiming to provide theoretical basis and directions for searching new potential candidate drugs to promote bone formation.
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Objective To investigate the mechanism of 3-phosphoinositide-dependent protein kinase 1(PDK1)poly-ubiquitination.Methods Co-immunoprecipitation(Co-IP)and Western blot(WB)were used to analyze poly-ubiquitination of PDK1.It was confirmed that ubiquitin ligase smad ubiquitylation regulatory factor 1(Smurf1)inprove PDK1 poly-ubiquitination within MEF cells,site-directed mutagenesis and WB before PDK1 poly-ubiquitination sites were determined.Results We found that PDK1 could undergoes poly-ubiquitination,ubiquitin ligase Smurf1 was found to be a direct E3 ligase for PDK1 poly-ubiquitination and might rely on the ubiquitin ligase Smurf 1 K699 site activity.K304 was PDK1 poly-ubiquitination modification site point.Conclusion The ubiquitin ligase Smurf1 can promate poly-ubiquitination of PDK1.
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<p><b>BACKGROUND</b>To compare the clinicopathological features and prognosis between younger and aged patients with hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>We analyzed the outcome of 451 HCC patients underwent liver resection, transcatheter arterial chemoembolization and radiofrequency ablation, respectively. Then risk factors for aged and younger patients' survival were evaluated by multivariate analysis, respectively.</p><p><b>RESULTS</b>The patients who were older than 55 years old were defined as the older group. The overall survival for aged patients was significantly worse than those younger patients. The younger patients had similar liver functional reserve but more aggressive tumor factors than aged patients. Cox regression analysis showed that the elevated levels of aspartate aminotransferase (AST) (Wald χ2 = 3.963, P = 0.047, hazard ratio [HR] =1.453, 95% confidence interval [CI]: 1.006-2.098), lower albumin (Wald χ2 = 12.213, P < 0.001, HR = 1.982, 95% CI: 1.351-2.910), tumor size (Wald χ2 = 8.179, P = 0.004, HR = 1.841, 95% CI: 1.212-2.797), and higher alpha-fetoprotein level (Wald χ2 = 4.044, P = 0.044, HR = 1.465, 95% CI: 1.010-2.126) were independent prognostic factors for aged patients, while only elevated levels of AST (Wald χ2 = 14.491, P < 0.001, HR = 2.285, 95% CI: 1.493-3.496) and tumor size (Wald χ2 = 21.662, P < 0.001, HR = 2.928, 95% CI: 1.863-4.604) were independent prognostic factors for younger patients.</p><p><b>CONCLUSIONS</b>Age is a risk factor to determine the prognosis of patients with HCC. Aged patients who have good liver functional reserve are still encouraged to receive curative therapy.</p>
Subject(s)
Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Young Adult , Age Factors , Carcinoma, Hepatocellular , Mortality , Liver Neoplasms , Mortality , Retrospective Studies , Survival AnalysisABSTRACT
Objective To study the expression of the fused proteasome activator REGγ(11S regulator complex gamma subunit) using gene recombination technology and to further study the interaction between REGγ and casein kinase-2 interacting protein-1(CKIP-1)in vitro.Methods Firstly, the full length cDNA fragment of REGγ was amplified through PCR using the plasmid pCMV-Myc-REGγ as template and subcloned into the prokaryotic expression vector pGEX-4T-2 before being transformed into E.coli BL21 cells. The protein expression was induced by isopropyl-β-D-thiogalactoside(IPTG) .Secondly, the protein expression was monitored by SDS-PAGE and Western blotting after ultrasonication. Finally, the GST Pull-down assay was performed to investigate the interaction between REGγ and CKIP-1 in vitro.Results The prokaryotic expression construct pGEX-4T-2-REGγ was generated successfully and confirmed by DNA sequencing. Expression analysis showed that the GST-REGγ protein was easily expressed and isolated mainly in the lysate supernatant after sonication and centrifugation. The GST Pull-down assay revealed the strong mutual interaction between REGγ and CKIP-1 in vitro.Conclusion The proteasome activator REGγ could interact with the negative regulator of osteoblastogenesis CKIP-1 in vitro and the current study has shed light on further investigations of their physiological relevance.
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Scansite is a short linear motif-based scanning approach established in the latest two years. It's accessible over the World Wide Web and can be used to identify sequence motifs likely to be phosphorylated by specific protein kinases or likely to bind to specific protein domains such as 14-3-3, SH2 and SH3 domains. The usage and function of the potent approach were reviewed and compared with previously established tools for phosphorylation prediction. The facing problems and application outlook of Scansite in prediction of cell signaling networks within proteomes were also presented.