Calreticulin activates {beta}1-integrin through fucosylation modification by fucosyltransferase-1 in J82 human bladder cancer cells
In conclusion, our findings suggested that CRT stabilized FUT1 mRNA, thereby leading to increase in fucosylation of β1-integrin. Furthermore, increased fucosylation levels activate β1-integrin rather than directly modifying the integrin binding sites. (Source: BJ Cell)
Source: BJ Cell - March 4, 2014 Category: Biochemistry Authors: Y Lu, C Chen, C Chu, J Lu, B Wang, C Chen, M Huang, T Lin, C Pan, S Alex Chen, W Hsu, Y Liao, P Wu, H Hsia, C Chang, H Lee Tags: BJ Biomolecules Source Type: research
Glutamyl-tRNAGln amidotransferase is essential for mammalian mitochondrial translation in vivo
Translational accuracy depends on the correct formation of aminoacyl-tRNAs which, in the majority of cases, are produced by specific aminoacyl-tRNA synthetases that ligate each amino acid to its cognate isoaceptor tRNA. Aminoacylation of tRNAGln, however, is performed by various mechanisms in different systems. Since no mitochondrial glutaminyl-tRNA synthetase has been identified to date in mammalian mitochondria, Gln-tRNAGln has to be formed by an indirect mechanism in the organelle. It has been demonstrated that human mitochondria contain a non-discriminating glutamyl-tRNA synthetase and the heterotrimeric enzyme glutamy...
Source: BJ Cell - March 3, 2014 Category: Biochemistry Authors: L Echevarría, P Clemente, R Hernández Sierra, M Gallardo, M A. Fernández-Moreno, R Garesse Tags: BJ Metabolism Source Type: research
Functional divergence between the two P1-P2 stalk dimers on the ribosome in their interaction with ricin A chain
The eukaryotic stalk, which is responsible for recruitment of the translation factors, is a pentamer containing two P1-P2 dimers with unclear modes of action. In S. cerevisiae P1/P2 are organized into two distinct dimers, P1A-P2B and P1B-P2A. To investigate the functional contribution of each dimer on the ribosome, ricin A chain (RTA), which binds to the stalk to depurinate the sarcin/ricin loop (SRL), was used as a molecular probe in yeast mutants in which the binding site for one or the other dimer on P0 was deleted. Ribosome depurination and toxicity of RTA were greatly reduced in mutants containing only P1A-P2B on the ...
Source: BJ Cell - February 28, 2014 Category: Biochemistry Authors: P Grela, X Li, M Tchorzewski, N E Tumer Tags: BJ Cell Source Type: research
In vitro characterization of bacterial and chloroplast HSP70 systems reveals an evolutionary optimization of the co-chaperones for their HSP70 partner
The chloroplast Hsp70 system involved in protein folding in Chlamydomonas reinhardtii consists of HSP70B, the DnaJ homolog CDJ1, and the GrpE-type nucleotide exchange factor CGE1. The finding that HSP70B needs to be co-expressed with the escort protein HEP2 to become functional allowed reconstituting the chloroplast Hsp70 system in vitro and comparing it with the homologous E. coli system. Both systems support luciferase refolding and display ATPase and holdase activities. Steady-state activities are low and strongly stimulated by the co-chaperones, whose concentrations need to be balanced to optimally support luciferase r...
Source: BJ Cell - February 25, 2014 Category: Biochemistry Authors: D Veyel, F Sommer, L Segatto Muranaka, M Rütgers, S D. Lemaire, M Schroda Tags: BJ Plant Source Type: research
The Upstream Conserved Regions (UCRs) Mediate Homo- and Hetero-oligomerization of Type 4 Cyclic Nucleotide Phosphodiesterases (PDE4s)
Type 4 cyclic nucleotide phosphodiesterases (PDE4s) are divided into long and short forms by the presence or absence of conserved N-terminal domains termed upstream conserved regions (UCRs). We have shown previously that PDE4D2, a short variant, is a monomer, whereas PDE4D3, a long variant, is a dimer. Here, we have determined the apparent molecular weights of various long and short PDE4 variants by size exclusion chromatography and sucrose density gradient centrifugation. Our results indicate that dimerization is a conserved property of all long PDE4 forms, whereas short forms are monomers. Dimerization is mediated by the...
Source: BJ Cell - February 21, 2014 Category: Biochemistry Authors: M Xie, B Blackman, C Scheitrum, D Mika, E Blanchard, T Lei, M Conti, W Richter Tags: BJ Signal Source Type: research
Lyn kinase plays important roles in erythroid expansion, maturation and Epo-receptor signaling by regulating inhibitory signaling pathways that control survival
Erythroid homeostasis is primarily controlled by Epo-receptor signaling, however the Lyn tyrosine kinase plays an important subsidiary role in regulating the erythroid compartment. Nonetheless, specific erythroid pathways that require Lyn activity and their biological significance remain unclear. To address this, we asked what consequence loss of Lyn had on the ex vivo expansion and maturation of splenic erythroid progenitors and Epo-receptor signaling. Pharmacological inhibition of Lyn with PP2 inhibited the survival of terminally differentiated erythroblasts. Less committed erythroid progenitors expanded well, while earl...
Source: BJ Cell - February 20, 2014 Category: Biochemistry Authors: N S. Slavova-Azmanova, N Kucera, A Louw, J Satiaputra, A Handoko, P Singer, L Stone, D J. McCarthy, S Peter Klinken, M L. Hibbs, E Ingley Tags: BJ Signal Source Type: research
Structural and mechanistic insights into an extracytoplasmic copper trafficking pathway in Streptomyces lividans
In Streptomyces lividans an extracytoplasmic copper binding Sco protein plays a role in two unlinked processes; 1) initiating a morphological development switch and 2) facilitating the co-factoring of the CuA domain of cytochrome c oxidase (CcO). How Sco obtains copper once secreted to the extracytoplasmic environment is unknown. Here we report on a protein possessing a HX6MX21HXM motif that binds a single cuprous ion with subfemtomolar affinity. High resolution X-ray structures of this extracytoplasmic copper chaperone-like protein (ECuC) in the apo- and Cu(I)-bound states reveal that the latter possesses a surface access...
Source: BJ Cell - February 19, 2014 Category: Biochemistry Authors: K L.I.M. Blundell, M A. Hough, E Vijgenboom, J A.R. Worrall Tags: BJ Biomolecules Source Type: research
Increased BIK expression following ERK1/2 pathway inhibition is a consequence of G1 cell cycle arrest and not a direct effect on BIK protein stability
BIK is a pro-apoptotic BH3-only protein and a member of the BCL2 protein family. It has recently been proposed that BIK abundance is controlled by ERK1/2-catalysed phosphorylation, which targets the protein for proteasome-dependent destruction. Here we have examined ERK1/2-dependent regulation of BIK drawing comparisons with BIMEL, a well-known target of ERK1/2. In many ERK1/2-dependent tumour cell lines inhibition of BRAFV600E or MEK1/2 had very little effect on BIK expression, whereas BIMEL was strongly up-regulated. In some cell lines we did observe a modest increase in BIK expression; however, this was not apparent unt...
Source: BJ Cell - February 17, 2014 Category: Biochemistry Authors: M J. Sale, S J. Cook Tags: BJ Signal Source Type: research
Suppression of adipogenesis by valproic acid through repression of USF1-activated fatty acid synthesis in adipocytes
In this study, we identified the molecular mechanism of VPA-mediated suppression of adipogenesis in adipocytes. VPA suppressed the accumulation of intracellular triglycerides. The expression levels of peroxisome proliferator-activated receptor γ and CCAAT/enhancer binding protein α, which are key regulators of adipogenesis, as well as the expression of stearoyl-CoA desaturase, were decreased by the treatment with VPA. Moreover, glycerol release was decreased in the VPA-treated cells; even though the transcription levels of adipose triglyceride lipase, hormone sensitive lipase, and monoacylglycerol lipase, all...
Source: BJ Cell - February 11, 2014 Category: Biochemistry Authors: M Yuyama, K Fujimori Tags: BJ Cell Source Type: research
Chitinase-3-like protein 1 protects skeletal muscle from TNF{alpha}-induced inflammation and insulin resistance
In conclusion, the novel myokine CHI3L1 which is induced by pro-inflammatory cytokines can counteract TNFα-mediated inflammation and insulin resistance in human skeletal muscle cells, potentially involving an auto/paracrine mechanism. (Source: BJ Cell)
Source: BJ Cell - February 11, 2014 Category: Biochemistry Authors: S W. Görgens, K Eckardt, M Elsen, N Tennagels, J Eckel Tags: BJ Metabolism Source Type: research
Redox signal regulation via nNOS phosphorylation at Ser847 in PC12 cells and rat cerebellar granule neurons
This report provides the first substantial corroboration for the biological effects of nNOS phosphorylation at Ser847 on redox signaling, including ROS and intracellular 8-nitro-cGMP generation in neurons, which possibly play roles in neuroprotection. (Source: BJ Cell)
Source: BJ Cell - February 6, 2014 Category: Biochemistry Authors: S Kasamatsu, Y Watanabe, T Sawa, T Akaike, H Ihara Tags: BJ Signal Source Type: research
Amino-terminus oligomerisation is conserved in intracellular calcium release channels
Oligomerisation of all three mammalian ryanodine receptor isoforms, a structural requirement for normal intracellular Ca2+ release channel function, is displayed by the discrete N-terminal domain which assembles into homo- and hetero-tetramers. This is demonstrated in yeast, mammalian cells and native tissue by complementary yeast two-hybrid, chemical cross-linking and co-immunoprecipitation assays. The IP3 receptor N-terminus (amino acids 1-667) similarly exhibits tetrameric association as indicated by chemical cross-linking and co-immunoprecipitation assays. The presence of either a 15-residue splice insertion or ...
Source: BJ Cell - February 6, 2014 Category: Biochemistry Authors: S Zissimopoulos, J Marsh, L Stannard, M Seidel, F Lai Tags: BJ Biomolecules Source Type: research
Resveratrol promotes degradation of the human bile acid transporter ASBT (SLC10A2)
The sodium/bile acid cotransporter ASBT (SLC10A2) plays a key role in the enterohepatic recycling of the bile acids and indirectly contributes to cholesterol homeostasis. ASBT inhibitors reportedly lower plasma triglyceride levels and increase HDL cholesterol levels. Resveratrol (RSV), a major constituent of red wine, is known to lower LDL cholesterol levels, but its mechanism of action is still unclear. Here, we studied the possible involvement of ASBT in RSV-mediated cholesterol lowering effects. We demonstrate that RSV inhibits ASBT protein expression and function via a SIRT1-independent mechanism. The effect was specif...
Source: BJ Cell - February 5, 2014 Category: Biochemistry Authors: P P. Chothe, P W. Swaan Tags: BJ Metabolism Source Type: research
Assembly of the TgrB1-TgrC1 cell adhesion complex during Dictyostelium discoideum development
In Dictyostelium discoideum, TgrB1 and TgrC1 are partners of a heterophilic cell adhesion system. To investigate its assembly process, the split GFP complementation assay was employed to track the oligomeric status of both proteins. The ability of TgrC1 to from cis-homodimers spontaneously was demonstrated by fluorescence complementation studies and confirmed by chemical cross-linking. In contrast, TgrB1 failed to form cis-homodimer in the absence of TgrC1. Treatment of cell aggregates with antibodies against TgrB1 or TgrC1 did not affect TgrC1 dimerization, but inhibited TgrB1 dimer formation, suggesting that TgrB1 cis-ho...
Source: BJ Cell - February 3, 2014 Category: Biochemistry Authors: G Chen, X Xu, X Wu, A Thomson, C Siu Tags: BJ Cell Source Type: research
Effects of Carbonic Anhydrase-Related Protein VIII on Human Cells Harboring A8344G Mitochondrial DNA Mutation
In this study, we show that there is a significant decrease of CA8 (carbonic anhydrase-related protein VIII) in cybrids harboring MERRF A8344G mutation. CA8 deficiency and mutations were found to be associated with a distinctive lifelong gait disorder in wdl (Waddles) mice and novel syndromes characterized by cerebellar ataxia and mental retardation in the human. Our results showed that overexpression of CA8 in MERRF cybrids significantly decreased cell death induced by (STS) staurosporine treatment, suggesting a protective function of CA8 in cells harboring the A8344G mutation of mtDNA.Interestingly, an increase in the fo...
Source: BJ Cell - January 30, 2014 Category: Biochemistry Authors: T Wang, C Cheng, T Chi, Y Ma, S Wu, Y Wei, M Hsieh Tags: BJ Disease Source Type: research
