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Ligase Complex (ligase + complex)
Selected Abstracts2-oxoglutarate downregulates expression of vascular endothelial growth factor and erythropoietin through decreasing hypoxia-inducible factor-1, and inhibits angiogenesisJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2006Ken Matsumoto In oxygenated cells, hypoxia-inducible factor-1 (HIF-1) , subunits are rapidly degraded by a mechanism that involves ubiquitination by the von Hippel,Lindau tumor suppressor E3 ligase complex using 2-oxoglutarate as a substrate. We examined the effect of 2-oxoglutarate on the production of erythropoietin and vascular endothelial growth factor (VEGF). The expression of erythropoietin and VEGF protein were dose-dependently downregulated in Hep3B cells by the addition of 2-oxoglutarate. The promoter activity of VEGF-luciferase was dose-dependently downregulated by the addition of 2-oxoglutarate. Gel mobility shift assays revealed that the addition of 2-oxoglutarate dose-dependently inhibited HIF-1 binding activity, but did not affect GATA binding activity. Western blot analysis revealed that 2-oxoglutarate dose-dependently inhibited the HIF-1, protein level in Hep3B cells in hypoxic conditions. However, MG132 (the proteasome inhibitor) rescued the inhibition of HIF-1, protein expression by 2-oxoglutarate. Furthermore, under hypoxic conditions, 2-oxoglutarate dose-dependently inhibited tube formation in in vitro angiogenesis assays. These results indicate that 2-oxoglutarate treatment may be useful for the inhibition of angiogenesis. J. Cell. Physiol. 209: 333,340, 2006. © 2006 Wiley-Liss, Inc. [source] Association between activation of atypical NF-,B1 p105 signaling pathway and nuclear ,-catenin accumulation in colorectal carcinomaMOLECULAR CARCINOGENESIS, Issue 2 2010Johannes C. Lauscher Abstract Recent studies have demonstrated that increased expression of coding region determinant-binding protein (CRD-BP) in response to ,-catenin signaling leads to the stabilization of ,-TrCP1, a substrate-specific component of SCF E3 ubiquitin ligase complex, resulting in an accelerated degradation of I,B, and activation of canonical nuclear factor-,B (NF-,B) pathway. Here, we show that the noncanonical NF-,B1 p105 pathway is constitutively activated in colorectal carcinoma specimens, being particularly associated with ,-catenin-mediated increased expression of CRD-BP and ,-TrCP1. In the carcinoma tissues exhibiting high levels of nuclear ,-catenin the phospho-p105 levels were increased and total p105 amounts were decreased in comparison to that of normal tissue indicating an activation of this NF-,B pathway. Knockdown of CRD-BP in colorectal cancer cell line SW620 resulted in significantly higher basal levels of both NF-,B inhibitory proteins, p105 and I,B,. Furthermore decreased NF-,B binding activity was observed in CRD-BP siRNA-transfected SW620 cells as compared with those transfected with control siRNA. Altogether, our findings suggest that activation of NF-,B1 p105 signaling in colorectal carcinoma might be attributed to ,-catenin-mediated induction of CRD-BP and ,-TrCP1. © 2009 Wiley-Liss, Inc. [source] SGT1 positively regulates the process of plant cell death during both compatible and incompatible plant,pathogen interactionsMOLECULAR PLANT PATHOLOGY, Issue 5 2010KERI WANG SUMMARY SGT1 (suppressor of G2 allele of Skp1), an interactor of SCF (Skp1-Cullin-F-box) ubiquitin ligase complexes that mediate protein degradation, plays an important role at both G1,S and G2,M cell cycle transitions in yeast, and is highly conserved throughout eukaryotes. Plant SGT1 is required for both resistance (R) gene-mediated disease resistance and nonhost resistance to certain pathogens. Using virus-induced gene silencing (VIGS) in Nicotiana benthamiana, we demonstrate that SGT1 positively regulates the process of cell death during both host and nonhost interactions with various pathovars of Pseudomonas syringae. Silencing of NbSGT1 in N. benthamiana plants delays the induction of hypersensitive response (HR)-mediated cell death against nonhost pathogens and the development of disease-associated cell death caused by the host pathogen P. syringae pv. tabaci. Our results further demonstrate that NbSGT1 is required for Erwinia carotovora - and Sclerotinia sclerotiorum -induced disease-associated cell death. Overexpression of NbSGT1 in N. benthamiana accelerates the development of HR during R gene-mediated disease resistance and nonhost resistance. Our data also indicate that SGT1 is required for pathogen-induced cell death, but is not always necessary for the restriction of bacterial multiplication in planta. Therefore, we conclude that SGT1 is an essential component affecting the process of cell death during both compatible and incompatible plant,pathogen interactions. [source] Crystallization and preliminary X-ray characterization of the Skp1,Fbg3 complexACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2010Taichi Kumanomidou F-box proteins are the substrate-recognition components of Skp1,Cullin1,F-box protein,Rbx1 (SCF) ubiquitin ligase complexes. Fbs1, an F-box protein, binds specifically to proteins modified with high-mannose oligosaccharides. Fbg3, another F-box protein, has 51% sequence identity to Fbs1. Although the residues that are necessary for binding to oligosaccharides are conserved between Fbs1 and Fbg3, Fbg3 does not bind glycoproteins. Skp1 and Fbg3 were co-expressed in Escherichia coli and their complex was purified to homogeneity and crystallized. Microseeding combined with the sandwiched hanging-drop technique improved the quality of the resulting crystals. The plate-shaped crystals belonged to space group P212121, with unit-cell parameters a = 34.1, b = 76.6, c = 193.9,Å and one molecule per asymmetric unit. [source] | ||||||||||