ic Integrated Genomic and Proteomic Analyses of Gene Expression in Mammalian Cells By feedproxy.google.com Published On :: 2004-10-01 Qiang TianOct 1, 2004; 3:960-969Research Full Article
ic Interpretation of Shotgun Proteomic Data: The Protein Inference Problem By feedproxy.google.com Published On :: 2005-10-01 Alexey I. NesvizhskiiOct 1, 2005; 4:1419-1440Tutorial Full Article
ic GPS 2.0, a Tool to Predict Kinase-specific Phosphorylation Sites in Hierarchy By feedproxy.google.com Published On :: 2008-09-01 Yu XueSep 1, 2008; 7:1598-1608Research Full Article
ic A Human Protein Atlas for Normal and Cancer Tissues Based on Antibody Proteomics By feedproxy.google.com Published On :: 2005-12-01 Mathias UhlénDec 1, 2005; 4:1920-1932Research Full Article
ic Comparison of Label-free Methods for Quantifying Human Proteins by Shotgun Proteomics By feedproxy.google.com Published On :: 2005-10-01 William M. OldOct 1, 2005; 4:1487-1502Research Full Article
ic Quantitative Mass Spectrometric Multiple Reaction Monitoring Assays for Major Plasma Proteins By feedproxy.google.com Published On :: 2006-04-01 Leigh AndersonApr 1, 2006; 5:573-588Research Full Article
ic Quantitative Phosphoproteomics Applied to the Yeast Pheromone Signaling Pathway By feedproxy.google.com Published On :: 2005-03-01 Albrecht GruhlerMar 1, 2005; 4:310-327Research Full Article
ic Highly Selective Enrichment of Phosphorylated Peptides from Peptide Mixtures Using Titanium Dioxide Microcolumns By feedproxy.google.com Published On :: 2005-07-01 Martin R. LarsenJul 1, 2005; 4:873-886Technology Full Article
ic Absolute Quantification of Proteins by LCMSE: A Virtue of Parallel ms Acquisition By feedproxy.google.com Published On :: 2006-01-01 Jeffrey C. SilvaJan 1, 2006; 5:144-156Research Full Article
ic The Human Plasma Proteome: History, Character, and Diagnostic Prospects By feedproxy.google.com Published On :: 2002-11-01 N. Leigh AndersonNov 1, 2002; 1:845-867Reviews/Perspectives Full Article
ic Analysis of the Human Tissue-specific Expression by Genome-wide Integration of Transcriptomics and Antibody-based Proteomics By feedproxy.google.com Published On :: 2014-02-01 Linn FagerbergFeb 1, 2014; 13:397-406Research Full Article
ic A Versatile Nanotrap for Biochemical and Functional Studies with Fluorescent Fusion Proteins By feedproxy.google.com Published On :: 2008-02-01 Ulrich RothbauerFeb 1, 2008; 7:282-289Research Full Article
ic Exponentially Modified Protein Abundance Index (emPAI) for Estimation of Absolute Protein Amount in Proteomics by the Number of Sequenced Peptides per Protein By feedproxy.google.com Published On :: 2005-09-01 Yasushi IshihamaSep 1, 2005; 4:1265-1272Research Full Article
ic Multiplexed Protein Quantitation in Saccharomyces cerevisiae Using Amine-reactive Isobaric Tagging Reagents By feedproxy.google.com Published On :: 2004-12-01 Philip L. RossDec 1, 2004; 3:1154-1169Research Full Article
ic Accurate Proteome-wide Label-free Quantification by Delayed Normalization and Maximal Peptide Ratio Extraction, Termed MaxLFQ By feedproxy.google.com Published On :: 2014-09-01 Jürgen CoxSep 1, 2014; 13:2513-2526Technological Innovation and Resources Full Article
ic Stable Isotope Labeling by Amino Acids in Cell Culture, SILAC, as a Simple and Accurate Approach to Expression Proteomics By feedproxy.google.com Published On :: 2002-05-01 Shao-En OngMay 1, 2002; 1:376-386Research Full Article
ic Reply to Cosgrove: Non-enzymatic action of expansins [Letters to the Editor] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 In our computational study, we use molecular simulations to substantiate a hypothetical mechanism for glycosidic bond cleavage in the presence of a single catalytic acid at the active site of the mutant D10N HiCel45A. In addition to discussing this plausible mechanism from the context of structurally related MltA lytic transglycosylase and subfamily C GH45s, we also suggest the implications of the plausible mechanism for our current understanding of the action of expansins and lytic transglycosylases. As correctly pointed out by Professor Cosgrove (1), there is large body of evidence, a significant portion of which was regrettably not discussed in our paper, that suggests that expansins are incapable of lytic action on polysaccharide substrates. Whereas these insights do not change the results or the conclusions of our article, we would like to thank Professor Cosgrove for these additional insights. In particular, our main point with respect to expansins is that our results suggest the possibility that expansins are capable of nonhydrolytic lytic activity. Our intention was not to suggest this was the mechanism of expansins, but that it should be considered based on our results and the similarity of the active sites.The molecular mechanisms of how expansins enable cell wall expansion remains to be fully understood. Whereas our proposed mechanism resulting in the formation of the 1,6-anhdro product might be found in expansins and might contribute to the mode of action of expansins, we would like to emphasize that the intent of this study was only to suggest this as a... Full Article
ic Non-enzymatic action of expansins [Letters to the Editor] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 From their simulations of endoglucanase Cel45A, Bharadwaj et al. (1) propose that structurally related expansins and MltA may cut glycan backbones without generating reducing ends. This is tenable for MltA, a peptidoglycan lytic transglycosylase whose action produces nonreducing 1,6-anhydro products, but is untenable for expansins.Expansins loosen plant cell walls and induce wall expansion. Contrary to the assertion by Bharadwaj et al., the conclusion that expansins are not lytic is not merely based on lack of new reducing ends but is supported by multiple (negative) tests for polysaccharide cleavage that do not rely on detection of reducing ends. At least eight studies with three divergent groups of expansins document this point. For instance, α-expansin did not reduce the viscosity of various wall polysaccharide solutions, an endolytic assay that does not rely on measuring reducing ends (e.g. see Ref. 2 and other studies).Walls treated with α-expansin did not release saccharide fragments, measured by pulsed amperometric detection, which can detect nonreducing saccharides (3).In the case of β-expansins, protein treatments did not cleave the backbones of a wide range of dye-coupled cross-linked wall polysaccharides; nor did they cleave backbones of polysaccharides extracted from plant cell walls, measured by gel permeation chromatography (4).For five microbial expansins, tests with a range of dye-coupled cross-linked polysaccharides likewise did not detect lytic activity (e.g. see Ref. 5). Thus, extensive published evidence argues against lytic action by expansins, as proposed by Bharadwaj (1), and attempts to identify 1,6-anhydro products seem unlikely to succeed. Full Article
ic The cytochrome P450 enzyme CYP24A1 increases proliferation of mutant KRAS-dependent lung adenocarcinoma independent of its catalytic activity [Cell Biology] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 We previously reported that overexpression of cytochrome P450 family 24 subfamily A member 1 (CYP24A1) increases lung cancer cell proliferation by activating RAS signaling and that CYP24A1 knockdown inhibits tumor growth. However, the mechanism of CYP24A1-mediated cancer cell proliferation remains unclear. Here, we conducted cell synchronization and biochemical experiments in lung adenocarcinoma cells, revealing a link between CYP24A1 and anaphase-promoting complex (APC), a key cell cycle regulator. We demonstrate that CYP24A1 expression is cell cycle–dependent; it was higher in the G2-M phase and diminished upon G1 entry. CYP24A1 has a functional destruction box (D-box) motif that allows binding with two APC adaptors, CDC20-homologue 1 (CDH1) and cell division cycle 20 (CDC20). Unlike other APC substrates, however, CYP24A1 acted as a pseudo-substrate, inhibiting CDH1 activity and promoting mitotic progression. Conversely, overexpression of a CYP24A1 D-box mutant compromised CDH1 binding, allowing CDH1 hyperactivation, thereby hastening degradation of its substrates cyclin B1 and CDC20, and accumulation of the CDC20 substrate p21, prolonging mitotic exit. These activities also occurred with a CYP24A1 isoform 2 lacking the catalytic cysteine (Cys-462), suggesting that CYP24A1's oncogenic potential is independent of its catalytic activity. CYP24A1 degradation reduced clonogenic survival of mutant KRAS-driven lung cancer cells, and calcitriol treatment increased CYP24A1 levels and tumor burden in Lsl-KRASG12D mice. These results disclose a catalytic activity-independent growth-promoting role of CYP24A1 in mutant KRAS-driven lung cancer. This suggests that CYP24A1 could be therapeutically targeted in lung cancers in which its expression is high. Full Article
ic 12-LOX catalyzes the oxidation of 2-arachidonoyl-lysolipids in platelets generating eicosanoid-lysolipids that are attenuated by iPLA2{gamma} knockout [Signal Transduction] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 The canonical pathway of eicosanoid production in most mammalian cells is initiated by phospholipase A2-mediated release of arachidonic acid, followed by its enzymatic oxidation resulting in a vast array of eicosanoid products. However, recent work has demonstrated that the major phospholipase in mitochondria, iPLA2γ (patatin-like phospholipase domain containing 8 (PNPLA8)), possesses sn-1 specificity, with polyunsaturated fatty acids at the sn-2 position generating polyunsaturated sn-2-acyl lysophospholipids. Through strategic chemical derivatization, chiral chromatographic separation, and multistage tandem MS, here we first demonstrate that human platelet-type 12-lipoxygenase (12-LOX) can directly catalyze the regioselective and stereospecific oxidation of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC) and 2-arachidonoyl-lysophosphatidylethanolamine (2-AA-LPE). Next, we identified these two eicosanoid-lysophospholipids in murine myocardium and in isolated platelets. Moreover, we observed robust increases in 2-AA-LPC, 2-AA-LPE, and their downstream 12-LOX oxidation products, 12(S)-HETE-LPC and 12(S)-HETE-LPE, in calcium ionophore (A23187)-stimulated murine platelets. Mechanistically, genetic ablation of iPLA2γ markedly decreased the calcium-stimulated production of 2-AA-LPC, 2-AA-LPE, and 12-HETE-lysophospholipids in mouse platelets. Importantly, a potent and selective 12-LOX inhibitor, ML355, significantly inhibited the production of 12-HETE-LPC and 12-HETE-LPE in activated platelets. Furthermore, we found that aging is accompanied by significant changes in 12-HETE-LPC in murine serum that were also markedly attenuated by iPLA2γ genetic ablation. Collectively, these results identify previously unknown iPLA2γ-initiated signaling pathways mediated by direct 12-LOX oxidation of 2-AA-LPC and 2-AA-LPE. This oxidation generates previously unrecognized eicosanoid-lysophospholipids that may serve as biomarkers for age-related diseases and could potentially be used as targets in therapeutic interventions. Full Article
ic Heterotrimeric Gq proteins as therapeutic targets? [Molecular Bases of Disease] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Heterotrimeric G proteins are the core upstream elements that transduce and amplify the cellular signals from G protein–coupled receptors (GPCRs) to intracellular effectors. GPCRs are the largest family of membrane proteins encoded in the human genome and are the targets of about one-third of prescription medicines. However, to date, no single therapeutic agent exerts its effects via perturbing heterotrimeric G protein function, despite a plethora of evidence linking G protein malfunction to human disease. Several recent studies have brought to light that the Gq family–specific inhibitor FR900359 (FR) is unexpectedly efficacious in silencing the signaling of Gq oncoproteins, mutant Gq variants that mostly exist in the active state. These data not only raise the hope that researchers working in drug discovery may be able to potentially strike Gq oncoproteins from the list of undruggable targets, but also raise questions as to how FR achieves its therapeutic effect. Here, we place emphasis on these recent studies and explain why they expand our pharmacological armamentarium for targeting Gq protein oncogenes as well as broaden our mechanistic understanding of Gq protein oncogene function. We also highlight how this novel insight impacts the significance and utility of using G(q) proteins as targets in drug discovery efforts. Full Article
ic Noncatalytic Bruton's tyrosine kinase activates PLC{gamma}2 variants mediating ibrutinib resistance in human chronic lymphocytic leukemia cells [Membrane Biology] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 Treatment of patients with chronic lymphocytic leukemia (CLL) with inhibitors of Bruton's tyrosine kinase (BTK), such as ibrutinib, is limited by primary or secondary resistance to this drug. Examinations of CLL patients with late relapses while on ibrutinib, which inhibits BTK's catalytic activity, revealed several mutations in BTK, most frequently resulting in the C481S substitution, and disclosed many mutations in PLCG2, encoding phospholipase C-γ2 (PLCγ2). The PLCγ2 variants typically do not exhibit constitutive activity in cell-free systems, leading to the suggestion that in intact cells they are hypersensitive to Rac family small GTPases or to the upstream kinases spleen-associated tyrosine kinase (SYK) and Lck/Yes-related novel tyrosine kinase (LYN). The sensitivity of the PLCγ2 variants to BTK itself has remained unknown. Here, using genetically-modified DT40 B lymphocytes, along with various biochemical assays, including analysis of PLCγ2-mediated inositol phosphate formation, inositol phospholipid assessments, fluorescence recovery after photobleaching (FRAP) static laser microscopy, and determination of intracellular calcium ([Ca2+]i), we show that various CLL-specific PLCγ2 variants such as PLCγ2S707Y are hyper-responsive to activated BTK, even in the absence of BTK's catalytic activity and independently of enhanced PLCγ2 phospholipid substrate supply. At high levels of B-cell receptor (BCR) activation, which may occur in individual CLL patients, catalytically-inactive BTK restored the ability of the BCR to mediate increases in [Ca2+]i. Because catalytically-inactive BTK is insensitive to active-site BTK inhibitors, the mechanism involving the noncatalytic BTK uncovered here may contribute to preexisting reduced sensitivity or even primary resistance of CLL to these drugs. Full Article
ic G{alpha}q splice variants mediate phototransduction, rhodopsin synthesis, and retinal integrity in Drosophila [Signal Transduction] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 Heterotrimeric G proteins mediate a variety of signaling processes by coupling G protein–coupled receptors to intracellular effector molecules. In Drosophila, the Gαq gene encodes several Gαq splice variants, with the Gαq1 isoform protein playing a major role in fly phototransduction. However, Gαq1 null mutant flies still exhibit a residual light response, indicating that other Gαq splice variants or additional Gq α subunits are involved in phototransduction. Here, we isolated a mutant fly with no detectable light responses, decreased rhodopsin (Rh) levels, and rapid retinal degeneration. Using electrophysiological and genetic studies, biochemical assays, immunoblotting, real-time RT-PCR, and EM analysis, we found that mutations in the Gαq gene disrupt light responses and demonstrate that the Gαq3 isoform protein is responsible for the residual light response in Gαq1 null mutants. Moreover, we report that Gαq3 mediates rhodopsin synthesis. Depletion of all Gαq splice variants led to rapid light-dependent retinal degeneration, due to the formation stable Rh1-arrestin 2 (Arr2) complexes. Our findings clarify essential roles of several different Gαq splice variants in phototransduction and retinal integrity in Drosophila and reveal that Gαq3 functions in rhodopsin synthesis. Full Article
ic NF-{kappa}B mediates lipopolysaccharide-induced alternative pre-mRNA splicing of MyD88 in mouse macrophages [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 Although a robust inflammatory response is needed to combat infection, this response must ultimately be terminated to prevent chronic inflammation. One mechanism that terminates inflammatory signaling is the production of alternative mRNA splice forms in the Toll-like receptor (TLR) signaling pathway. Whereas most genes in the TLR pathway encode positive mediators of inflammatory signaling, several, including that encoding the MyD88 signaling adaptor, also produce alternative spliced mRNA isoforms that encode dominant-negative inhibitors of the response. Production of these negatively acting alternatively spliced isoforms is induced by stimulation with the TLR4 agonist lipopolysaccharide (LPS); thus, this alternative pre-mRNA splicing represents a negative feedback loop that terminates TLR signaling and prevents chronic inflammation. In the current study, we investigated the mechanisms regulating the LPS-induced alternative pre-mRNA splicing of the MyD88 transcript in murine macrophages. We found that 1) the induction of the alternatively spliced MyD88 form is due to alternative pre-mRNA splicing and not caused by another RNA regulatory mechanism, 2) MyD88 splicing is regulated by both the MyD88- and TRIF-dependent arms of the TLR signaling pathway, 3) MyD88 splicing is regulated by the NF-κB transcription factor, and 4) NF-κB likely regulates MyD88 alternative pre-mRNA splicing per se rather than regulating splicing indirectly by altering MyD88 transcription. We conclude that alternative splicing of MyD88 may provide a sensitive mechanism that ensures robust termination of inflammation for tissue repair and restoration of normal tissue homeostasis once an infection is controlled. Full Article
ic Biophysical characterization of SARAH domain-mediated multimerization of Hippo pathway complexes in Drosophila [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 Hippo pathway signaling limits cell growth and proliferation and maintains the stem-cell niche. These cellular events result from the coordinated activity of a core kinase cassette that is regulated, in part, by interactions involving Hippo, Salvador, and dRassF. These interactions are mediated by a conserved coiled-coil domain, termed SARAH, in each of these proteins. SARAH domain–mediated homodimerization of Hippo kinase leads to autophosphorylation and activation. Paradoxically, SARAH domain–mediated heterodimerization between Hippo and Salvador enhances Hippo kinase activity in cells, whereas complex formation with dRassF inhibits it. To better understand the mechanism by which each complex distinctly modulates Hippo kinase and pathway activity, here we biophysically characterized the entire suite of SARAH domain–mediated complexes. We purified the three SARAH domains from Drosophila melanogaster and performed an unbiased pulldown assay to identify all possible interactions, revealing that isolated SARAH domains are sufficient to recapitulate the cellular assemblies and that Hippo is a universal binding partner. Additionally, we found that the Salvador SARAH domain homodimerizes and demonstrate that this interaction is conserved in Salvador's mammalian homolog. Using native MS, we show that each of these complexes is dimeric in solution. We also measured the stability of each SARAH domain complex, finding that despite similarities at both the sequence and structural levels, SARAH domain complexes differ in stability. The identity, stoichiometry, and stability of these interactions characterized here comprehensively reveal the nature of SARAH domain–mediated complex formation and provide mechanistic insights into how SARAH domain–mediated interactions influence Hippo pathway activity. Full Article
ic Mechanistic insights explain the transforming potential of the T507K substitution in the protein-tyrosine phosphatase SHP2 [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 The protein-tyrosine phosphatase SHP2 is an allosteric enzyme critical for cellular events downstream of growth factor receptors. Mutations in the SHP2 gene have been linked to many different types of human diseases, including developmental disorders, leukemia, and solid tumors. Unlike most SHP2-activating mutations, the T507K substitution in SHP2 is unique in that it exhibits oncogenic Ras-like transforming activity. However, the biochemical basis of how the SHP2/T507K variant elicits transformation remains unclear. By combining kinetic and biophysical methods, X-ray crystallography, and molecular modeling, as well as using cell biology approaches, here we uncovered that the T507K substitution alters both SHP2 substrate specificity and its allosteric regulatory mechanism. We found that although SHP2/T507K exists in the closed, autoinhibited conformation similar to the WT enzyme, the interactions between its N-SH2 and protein-tyrosine phosphatase domains are weakened such that SHP2/T507K possesses a higher affinity for the scaffolding protein Grb2-associated binding protein 1 (Gab1). We also discovered that the T507K substitution alters the structure of the SHP2 active site, resulting in a change in SHP2 substrate preference for Sprouty1, a known negative regulator of Ras signaling and a potential tumor suppressor. Our results suggest that SHP2/T507K's shift in substrate specificity coupled with its preferential association of SHP2/T507K with Gab1 enable the mutant SHP2 to more efficiently dephosphorylate Sprouty1 at pTyr-53. This dephosphorylation hyperactivates Ras signaling, which is likely responsible for SHP2/T507K's Ras-like transforming activity. Full Article
ic DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels [Cell Biology] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7−/− mice. Although palmitoylation of barttin in kidneys of Zdhhc7−/− animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7−/− mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension. Full Article
ic The focal adhesion protein kindlin-2 controls mitotic spindle assembly by inhibiting histone deacetylase 6 and maintaining {alpha}-tubulin acetylation [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 Kindlins are focal adhesion proteins that regulate integrin activation and outside-in signaling. The kindlin family consists of three members, kindlin-1, -2, and -3. Kindlin-2 is widely expressed in multiple cell types, except those from the hematopoietic lineage. A previous study has reported that the Drosophila Fit1 protein (an ortholog of kindlin-2) prevents abnormal spindle assembly; however, the mechanism remains unknown. Here, we show that kindlin-2 maintains spindle integrity in mitotic human cells. The human neuroblastoma SH-SY5Y cell line expresses only kindlin-2, and we found that when SH-SY5Y cells are depleted of kindlin-2, they exhibit pronounced spindle abnormalities and delayed mitosis. Of note, acetylation of α-tubulin, which maintains microtubule flexibility and stability, was diminished in the kindlin-2–depleted cells. Mechanistically, we found that kindlin-2 maintains α-tubulin acetylation by inhibiting the microtubule-associated deacetylase histone deacetylase 6 (HDAC6) via a signaling pathway involving AKT Ser/Thr kinase (AKT)/glycogen synthase kinase 3β (GSK3β) or paxillin. We also provide evidence that prolonged hypoxia down-regulates kindlin-2 expression, leading to spindle abnormalities not only in the SH-SY5Y cell line, but also cell lines derived from colon and breast tissues. The findings of our study highlight that kindlin-2 regulates mitotic spindle assembly and that this process is perturbed in cancer cells in a hypoxic environment. Full Article
ic Small-molecule agonists of the RET receptor tyrosine kinase activate biased trophic signals that are influenced by the presence of GFRa1 co-receptors [Neurobiology] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 Glial cell line–derived neurotrophic factor (GDNF) is a growth factor that regulates the health and function of neurons and other cells. GDNF binds to GDNF family receptor α1 (GFRa1), and the resulting complex activates the RET receptor tyrosine kinase and subsequent downstream signals. This feature restricts GDNF activity to systems in which GFRa1 and RET are both present, a scenario that may constrain GDNF breadth of action. Furthermore, this co-dependence precludes the use of GDNF as a tool to study a putative functional cross-talk between GFRa1 and RET. Here, using biochemical techniques, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and immunohistochemistry in murine cells, tissues, or retinal organotypic cultures, we report that a naphthoquinone/quinolinedione family of small molecules (Q compounds) acts as RET agonists. We found that, like GDNF, signaling through the parental compound Q121 is GFRa1-dependent. Structural modifications of Q121 generated analogs that activated RET irrespective of GFRa1 expression. We used these analogs to examine RET–GFRa1 interactions and show that GFRa1 can influence RET-mediated signaling and enhance or diminish AKT Ser/Thr kinase or extracellular signal-regulated kinase signaling in a biased manner. In a genetic mutant model of retinitis pigmentosa, a lead compound, Q525, afforded sustained RET activation and prevented photoreceptor neuron loss in the retina. This work uncovers key components of the dynamic relationships between RET and its GFRa co-receptor and provides RET agonist scaffolds for drug development. Full Article
ic Phosphoproteomic characterization of the signaling network resulting from activation of the chemokine receptor CCR2 [Genomics and Proteomics] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 Leukocyte recruitment is a universal feature of tissue inflammation and regulated by the interactions of chemokines with their G protein–coupled receptors. Activation of CC chemokine receptor 2 (CCR2) by its cognate chemokine ligands, including CC chemokine ligand 2 (CCL2), plays a central role in recruitment of monocytes in several inflammatory diseases. In this study, we used phosphoproteomics to conduct an unbiased characterization of the signaling network resulting from CCL2 activation of CCR2. Using data-independent acquisition MS analysis, we quantified both the proteome and phosphoproteome in FlpIn-HEK293T cells stably expressing CCR2 at six time points after activation with CCL2. Differential expression analysis identified 699 significantly regulated phosphorylation sites on 441 proteins. As expected, many of these proteins are known to participate in canonical signal transduction pathways and in the regulation of actin cytoskeleton dynamics, including numerous guanine nucleotide exchange factors and GTPase-activating proteins. Moreover, we identified regulated phosphorylation sites in numerous proteins that function in the nucleus, including several constituents of the nuclear pore complex. The results of this study provide an unprecedented level of detail of CCR2 signaling and identify potential targets for regulation of CCR2 function. Full Article
ic Inflammatory and mitogenic signals drive interleukin 23 subunit alpha (IL23A) secretion independent of IL12B in intestinal epithelial cells [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 The heterodimeric cytokine interleukin-23 (IL-23 or IL23A/IL12B) is produced by dendritic cells and macrophages and promotes the proinflammatory and regenerative activities of T helper 17 (Th17) and innate lymphoid cells. A recent study has reported that IL-23 is also secreted by lung adenoma cells and generates an inflammatory and immune-suppressed stroma. Here, we observed that proinflammatory tumor necrosis factor (TNF)/NF-κB and mitogen-activated protein kinase (MAPK) signaling strongly induce IL23A expression in intestinal epithelial cells. Moreover, we identified a strong crosstalk between the NF-κB and MAPK/ERK kinase (MEK) pathways, involving the formation of a transcriptional enhancer complex consisting of proto-oncogene c-Jun (c-Jun), RELA proto-oncogene NF-κB subunit (RelA), RUNX family transcription factor 1 (RUNX1), and RUNX3. Collectively, these proteins induced IL23A secretion, confirmed by immunoprecipitation of endogenous IL23A from activated human colorectal cancer (CRC) cell culture supernatants. Interestingly, IL23A was likely secreted in a noncanonical form, as it was not detected by an ELISA specific for heterodimeric IL-23 likely because IL12B expression is absent in CRC cells. Given recent evidence that IL23A promotes tumor formation, we evaluated the efficacy of MAPK/NF-κB inhibitors in attenuating IL23A expression and found that the MEK inhibitor trametinib and BAY 11–7082 (an IKKα/IκB inhibitor) effectively inhibited IL23A in a subset of human CRC lines with mutant KRAS or BRAFV600E mutations. Together, these results indicate that proinflammatory and mitogenic signals dynamically regulate IL23A in epithelial cells. They further reveal its secretion in a noncanonical form independent of IL12B and that small-molecule inhibitors can attenuate IL23A secretion. Full Article
ic Five Foreign Policy Questions for the UK’s Next Prime Minister By feedproxy.google.com Published On :: Tue, 18 Jun 2019 15:59:46 +0000 18 June 2019 Thomas Raines Director, Europe Programme @TomHRaines Google Scholar Even if most don’t get to vote in the Conservative leadership election, the public deserves serious answers on the foreign policy plans of those who want to lead the country. 2019-06-18-10D.jpg 10 Downing Street. Photo: Getty Images. In a month’s time, the UK will have a new prime minister. The campaign has been dominated by candidates’ views on how to deliver Britain’s withdrawal from the EU by October, alongside some discussion of domestic issues.But relatively little has been said about international affairs, despite the fact that foreign policy questions are becoming a more partisan issue and Britain is facing crucial questions around Brexit and the wider international context. These will be waiting for whoever finds themselves in Number 10 on 22 July. 1. How can Britain influence Europe from outside the EU?Theresa May was fond of saying that Britain is leaving the EU but not leaving Europe. Britain cannot change its geography. It will continue to share many strategic and security interests with the rest of the continent, but it will be outside of Europe’s central political and economic project. A new PM will not only have to negotiate Britain’s new relationship with the EU, but also think about how to influence it as a third country.An aspect of this will be finding a new way to work with the EU on foreign, security and defence policy that meets the need for autonomy on both sides. How deep this relationship is or how institutionalized it will be is yet to be negotiated and can be shaped by the next PM.The UK needs to decide how ambitiously it wants to engage with the new defence agenda in the EU (particularly its industrial components), and how to balance these with key bilateral relationships like France and Germany. Amid uncertainty about American security guarantees and Russian aggression, the next PM must also consider what Britain’s security role in Europe should be and NATO’s place within that.Beyond conventional foreign policy issues, Britain is also going to be heavily shaped and influenced by the rule-making power of the EU, and how the world’s largest market regulates itself, from energy to financial services, consumer products and the environment.The UK will need a strategy to influence the EU from the outside – something Swiss, Norwegians and Americans will acknowledge is no easy feat. This could include significantly increasing its diplomatic footprint across Europe, working closely with the UK’s private and non-profit sectors, utilizing Britain’s technical expertise in areas like sanctions, and creating new ad hoc groupings to share perspectives and ideas, building on examples like the Northern Future Forum. 2. Should Britain do business with President Trump?President Trump represents a fundamental challenge to Britain: an American president whose belligerent unilateralism runs counter to many of Britain’s foreign policy objectives. His frequent and often shameless diplomatic faux pas – from proposing Nigel Farage be the British ambassador to his dog-whistle attacks on the mayor of London – are compounded by real differences of substance on issues like trade, climate change and nuclear non-proliferation.A new prime minister must decide how to manage relations with the US administration, whether to challenge or condemn a US president when he acts against Britain’s interests, or use flattery or quieter diplomacy to seek to influence him. Theresa May’s strategy of staying politically close to the president and playing to his ego has yielded little in policy terms, though other world leaders have fared little better.A new PM will face some uncomfortable choices. Will they continue to defend the Iran nuclear deal alongside European allies while the US continues to undermine it? Do they believe a trade deal with America is desirable or achievable with the current administration, and what are they willing to sacrifice to achieve it? Is the American security guarantee for Europe secure with Donald Trump as president? Judgements on these questions should inform Britain's wider strategy, and its objectives for a future relationship with the European Union.3. Should Britain prioritize economics or security in its relations with China?Britain faces its own version of the challenge that many countries face – how to balance the economic and investment benefits of a positive relationship with China with concerns about repressive domestic politics and a more assertive Chinese role regionally and globally. This tension has become more acute for two reasons.First, the economic dislocation of leaving the EU may create a greater reliance on Chinese trade and investment. China is already a major investor in the UK. If Brexit proves to be disorderly, Britain’s need may be all the greater (though China faces economic headwinds as well). Some in Brussels even fear that the economic difficulties of Brexit may make the UK a soft touch for emerging powers from which it seeks inward investment and market access.Second, the deterioration in US–China relations means the UK may come under increasing pressure from the United States to take a tough line with China. The controversy over Huawei’s role in delivering 5G networks may become a more regular feature of transatlantic debates, with Britain facing Chinese economic pressure on one side and a squeeze from America over security issues on the other, without the weight of the EU behind it. A new prime minister should consider whether the UK’s interests are served by a security role in east Asia, and whether it has the capability to play one.The UK remains a party to the Five Power Defence Arrangements. The Royal Navy has conducted freedom of navigation exercises in the South China Sea, prompting a rebuke from Beijing. It has also taken steps to deepen security ties with Japan.But the UK government has struggled to present a coherent position. Some cabinet ministers have sought to open doors to the Chinese market at the same time as others announced their intentions to send aircraft carriers to the Pacific. The next PM will need to find a balance between China and the US, or accept the consequences of more directly taking sides on disputes about trade, technology, and security.4. How can the contradictions between UK foreign and domestic policy be reconciled?One of the many problems with the vague and unhelpful slogan ‘Global Britain’ is how it jars with many aspects of domestic policy. This incoherence reduces Britain’s foreign policy credibility and effectiveness.Britain has actively supported the UN-led Yemen peace process while continuing to support Saudi Arabia’s military campaign through arms sales. Britain wants to build a new ambitious independent trade policy while restricting the migration that is crucial for services trade. British foreign secretaries trumpet the UK’s soft power while the Home Office deports members of the Windrush generation, bungles EU citizenship applications and sets unreasonable burdens for many people seeking visas simply to visit the country.Global universities are celebrated while international students had their post-study visas cut (a policy that sensibly is likely to be reversed). Britain advocates international tax compliance and transparency while not taking robust steps to regulate the tax haven role played by crown dependencies and overseas territories.A new prime minister has the chance to get to grips with these inconsistencies and develop foreign and domestic policies which are more coherent and self-re-enforcing.5. At what level should Britain’s international ambitions be funded?Successive governments have celebrated the fact the UK is the only Western country to spend 2% of GDP on defence and 0.7% on development. However, this masks some real pressures in the system.There are significant problems in the defence budget and a growing gap between commitments and committed funds. Meanwhile, the funding of Britain’s diplomacy has been cut by successive governments – Labour, Conservative and coalition – for much of the last 20 years. Numerous bodies have highlighted the problems facing the overstretched and underfunded Foreign Office. Where would defence and diplomacy sit in the new prime minister’s hierarchy of priorities?The problem is not purely one of funding, but the gap between ambitions, rhetoric and resources. It is not sustainable for British ministers to trumpet Britain’s global ambitions while not properly funding the tools of its influence abroad.It would be reasonable and understandable for a new prime minister to adjust that ambition and tone down the rhetoric, or alternatively to address resource pressures by investing in diplomacy and defence. But that choice should be informed by a sober reflection on Britain’s international position and interests as it leaves the EU. Brexit offers a chance to revisit assumptions that have guided British policy for a generation. A new prime minister should seize this opportunity.A realistic vision for the futureAll these issues will be more pronounced if the UK leaves the EU with no deal at the end of October. ‘No deal’ would be not simply an economic shock but a diplomatic rupture that will colour the UK’s capacity to negotiate a new relationship with the EU, which will be the first order of business after a ‘no deal’ exit. Trust will be in short supply.Even if they don’t get to vote on the new prime minister, the public deserves serious answers to these and other questions from the men who want to lead the country. Not the platitudes of ‘Global Britain’ or a reflexive and unexamined British exceptionalism, but a serious, realistic assessment of how Britain will cope with the disruptions of leaving the EU and how it might thrive outside the regional bloc it has been a part of for more than 45 years. Full Article
ic Brexit, Party Politics and the Next Prime Minister By feedproxy.google.com Published On :: Fri, 28 Jun 2019 13:45:01 +0000 Invitation Only Research Event 15 July 2019 - 8:30am to 9:30am Chatham House | 10 St James's Square | London | SW1Y 4LE Event participants Daniel Finkelstein OBE, Associate Editor, The Times; Conservative Member of the House of Lords; Chairman, Onward Chair: Thomas Raines, Head, Europe Programme, Chatham House With the new leader of the Conservative party due to be announced on 23 July, what are the prospects for the party and the country?On Brexit, the new prime minister faces most of the same challenges and constraints as Theresa May. The leadership contenders have outlined their ambitions for a revised deal, but with the EU insisting negotiations are over, their room for manoeuvre appears to be limited. Furthermore, even with a new leader at the helm, important divisions remain among voters about what shape Brexit and the future UK-EU relationship should take. If the EU won’t change the deal, and parliament won’t accept it, how can the deadlock be broken? Is a 'No Deal' Brexit politically deliverable? Or could there be a general election later in 2019? Can the Conservative party survive a pre-Brexit election intact?Beyond Brexit, what are the other choices, in both domestic and foreign policy, facing the next prime minister? How might the decisions he makes affect the future of the party and British politics more broadly?In this session, the speaker will share his reflections on the likely result of the leadership election, and what lies beyond it.Attendance at this event is by invitation only. Event attributes Chatham House Rule Department/project Europe Programme, Britain and Europe: The Post-Referendum Agenda Alina Lyadova Europe Programme Coordinator Email Full Article
ic The Rise of China and the Future of the Transatlantic Relationship By feedproxy.google.com Published On :: Thu, 25 Jul 2019 15:03:09 +0000 29 July 2019 The growth of China's wealth and military power represents an epochal change in international politics. This briefing argues that China’s rise has worrying implications for the liberal international order and explores how this will affect the transatlantic relationship. Read online Download PDF Jennifer Lind Associate Fellow, US and the Americas Programme and Asia-Pacific Programme (based in the US) @proflind Google Scholar 2019-07-29-RiseOfChina.jpg Teams from France, Great Britain, the US, China, Australia and Japan race against each other during the SailGP on 4 May 2019 in San Francisco, California. Photo: Getty Images SummaryThe stakeholders in the transatlantic relationship – the US, Canada and Europe – have long sought to stabilize international politics and economies by spreading support for the liberal goals of free markets, democracy and human rights. As their own commitment to this agenda appears to waver, China is becoming wealthier and more assertive. This briefing explores the extent to which these goals – along with the unity of the transatlantic relationship – are now in jeopardy.Great uncertainty surrounds this question, including over the direction of US foreign policy, risks to European cohesion and slowing growth in China. However, two decades of revisionist behaviour by the authorities in Beijing show that China’s values and interests already conflict with transatlantic goals in trade, cyberspace, international development, security and human rights.On trade, China pursues protectionist policies while engaging actively in intellectual property theft. China’s military modernization and its view of maritime law challenge the territorial status quo in East Asia and raise the risk of military crisis there. China lends unconditionally to countries that abuse human rights and are corrupt, undermining efforts by Western governments to promote good governance and human rights.Defending liberal goals is complicated by asymmetric interests among the transatlantic partners, especially over security. China also uses ‘wedge’ strategies to pick off potential allies, thus diluting the power and will of any counterbalancing effort.This briefing argues that China’s rise has worrying implications for the liberal international order. In response, the US should recognize its own strong interest in European unity, while Europeans must be ready to align more with the US (and East Asian allies) in order to temper Chinese behaviour. Department/project Europe Programme, Asia-Pacific Programme, Geopolitics and Governance, EU-China 2025, US and the Americas Programme, Assessing the Transatlantic Relationship Full Article
ic Poland’s Elections: Domestic and Foreign Policy Implications By feedproxy.google.com Published On :: Wed, 18 Sep 2019 11:30:01 +0000 Research Event 30 September 2019 - 12:30pm to 1:30pm Chatham House | 10 St James's Square | London | SW1Y 4LE Event participants Dr Sławomir Dębski, Director, Polish Institute of International AffairsDr Stanley Bill, Senior Lecturer in Polish Studies, University of Cambridge On 13 October 2019, Poland goes to the polls in national elections. On the back of a strong performance in the European elections, the incumbent Law and Justice Party (PiS) is seeking to retain its absolute majority. The election takes place against a background of continued strong economic growth but amid disputes over the direction of social policy and a domestic contest about liberal values. The European Commission and the Polish government have clashed over reforms that the Commission believes could compromise the independence of the judiciary in the Poland. Meanwhile, in foreign policy terms, Poland has sought to develop good working relations with the Trump administration and supported a tough line towards Russia.The speakers will address the domestic and international significance of the Polish election. Will PiS be able to secure another majority? What would be the implications for the direction of social and political reform in Poland? And how could the elections shift Poland’s approach to politics at the European level and its wider foreign policy? Event attributes Chatham House Rule Department/project Europe Programme Alina Lyadova Europe Programme Coordinator Email Full Article
ic What Europe Can Learn From the Law and Justice Party’s Victory in Poland By feedproxy.google.com Published On :: Tue, 15 Oct 2019 14:39:52 +0000 15 October 2019 Dr Angelos Chryssogelos Associate Fellow, Europe Programme @AChryssogelos Google Scholar The EU must remain vigilant about threats to liberal democracy in Poland, but European leaders must also accept that PiS’s electoral success is reflective of its ability to deliver on things that other political parties in Europe have long neglected. 2019-10-15-PiS.jpg The button of a PiS supporter on election day. Photo: Getty Images. The Polish election on 13 October resulted, as expected, in a victory for of the ruling Law and Justice party (PiS).But despite again securing a slim majority in parliament, it has not been wholly a triumph for PiS. And though there continue to be concerns about the party’s authoritarian tendencies, the election has illuminated some important nuances to its support and appeal, which hold lessons for politics across Europe.Even though some opinion polls had suggested PiS were close to winning a supermajority in parliament that would have allowed it to pursue constitutional changes, the party fell short of that target, while it lost its majority in the Senate. Thus, while PiS may well renew its efforts to consolidate its control over the state apparatus and the media or meddle with the justice system, it becomes much more difficult with the opposition controlling the Senate and being able to scrutinize laws or have a say in the appointment of public officials.Most importantly, the election result has shown that while Polish citizens were willing to reward a party that delivered on promises of economic growth and redistribution, they were not ready to hand a blank cheque for full-blown institutional realignment to PiS. Tellingly, many moderate candidates in PiS lists performed quite well among the party’s voters. Even though they rewarded a party that at times employed harsh rhetoric against Brussels, Polish voters have long expressed some of the strongest rates of support for EU membership, according to Eurobarometer surveys. The government has also faced massive protests against its most radical initiatives, such as reform of the judicial system and a law to almost completely ban abortion that was ultimately scrapped. It is therefore more likely that the party’s radicalism kept it from increasing its share, rather than helping it to secure victory.This is not to say that the threat of illiberalism does not remain alive in Poland. But it shows that the degree of PiS dominance in Poland has never been comparable to that of Fidesz in Hungary, with which it is often compared.This was reflected in the party’s own rhetoric. In the election campaign the government mostly focused on its economic record, recognizing that much of its support is conditional on conventional measures of political success like voter welfare. PiS may not give up on its ambition to establish a ‘new Polish republic’, but the elections have made it clear that economic stability rather than political radicalism will ensure its longevity in power – with the latter perhaps even being a liability as the party experiences fatigue in office.Similarly, despite the government’s antagonistic stance towards the EU on various issues, PiS never entertained ideas of withdrawing from the EU, as some of its critics feared earlier in its term. With the Polish economy deeply entwined with the European market and Poland expecting – probably for the last time – to receive substantial subsidies from the next EU budget, EU membership is a necessary precondition for the economic success for which PiS is claiming credit.With the pro-European left returning to parliament but also an extreme party of the right winning representation, the next government will have a difficult balancing act as it tries to draw on the benefits of EU membership while maintaining its defiant image towards Brussels.Ultimately, beneath the rhetoric and the posturing, PiS is a party that has shrewdly combined popular policies from the left and right, fulfilling promises of both cultural sovereignty and economic redistribution. Its reelection should not come as a surprise given that it fulfilled its electoral pledges by delivering some of the things that many voters in western Europe also crave but that mainstream parties there have largely failed to provide. Full Article
ic Alice Billon-Galland By feedproxy.google.com Published On :: Fri, 01 Nov 2019 15:13:31 +0000 Research Associate, Europe Programme Biography Alice Billon-Galland is a research associate in the Europe programme, covering security and defence issues. Prior to joining Chatham House in October 2019, she led the European defence programme at the European Leadership Network (ELN) in London.Her research focuses on European security and defence issues, transatlantic burden-sharing, and the implementation of the new EU defence package. She also follows developments at NATO and in French foreign and defence policy, and regularly comments on defence issues for international media from Deutsche Welle to the Wall Street Journal.Alice is part of the Leadership Team of Women in International Security UK (WIIS UK) and a member of the Younger Generation Leaders Network on Euro-Atlantic Security (YGLN). She is also a 2018 GLOBSEC Young Leader.A graduate of France’s Ecole Normale Supérieure and holder of an agrégation of English language, Alice completed a Master’s degree in Public Policy at University College London and was a visiting scholar at Northwestern University in Chicago. Areas of expertise European security and defenceEU Common Security and Defence Policy (CSDP)NATO and EU-NATO relationsFrench foreign and defence policy Past experience 2017-19Policy fellow, European Leadership Network2017Researcher, European Leadership Network +44 (0)20-7314-3611 Email @alicebillon LinkedIn Full Article
ic Turkey in 2020 and Beyond: What Lies Ahead for Turkish Politics? By feedproxy.google.com Published On :: Wed, 06 Nov 2019 11:10:01 +0000 Invitation Only Research Event 25 November 2019 - 12:30pm to 1:30pm Chatham House | 10 St James's Square | London | SW1Y 4LE Event participants Fadi Hakura, Manager, Turkey Project, Europe Programme, Chatham House Turkey witnessed some major developments over the last year. In August 2018, the dramatic Lira devaluation caused the Turkish economy to go into recession. In the 2019 local elections, which took place during the economic downturn, the Republican Peoples’ Party (CHP) mayoral candidates took control of Ankara and Istanbul after 25 years of dominance by the ruling Justice and Development Party (AKP).The election results might lead to a rethink of the AKP leadership and consequences on Turkish politics will depend on Erdoğan’s interpretation of this reversal of his political fortune.Will this affect the long-standing alliance between AKP and MHP that has characterised Turkish foreign policy for the past few years? What impact will this have on both the domestic and international level? Finally, will Turkey’s recent incursion into Syria have lasting effect on the country’s alliances with other powers and its standing?In this context, the speaker will analyse the significance of these changes and the future trajectory of Turkish politics, economics and foreign policy. Event attributes Chatham House Rule Department/project Europe Programme, Turkey Project Alina Lyadova Europe Programme Coordinator Email Full Article
ic Why Britain’s 2019 Election Is Its Most Unpredictable in Recent History By feedproxy.google.com Published On :: Thu, 07 Nov 2019 15:33:23 +0000 7 November 2019 Professor Matthew Goodwin Visiting Senior Fellow, Europe Programme @GoodwinMJ LinkedIn Google Scholar Leadership concerns and a collapse of traditional party loyalties make the December vote uncommonly volatile. Explainer: UK General Election - Five Things to Watch On 12 December, Britain will hold the most consequential election in its postwar history. The outcome of the election will influence not only the fate of Brexit but also the likelihood of a second referendum on EU membership, a second independence referendum in Scotland, the most economically radical Labour Party for a generation, Britain’s foreign and security policy and, ultimately, its position in the wider international order.If you look only at the latest polls, then the outcome looks fairly certain. Ever since a majority of MPs voted to hold the election, the incumbent Conservative Party has averaged 38%, the opposition Labour Party 27%, the Liberal Democrats 16%, Brexit Party 10%, Greens 4% and Scottish National Party 3%. Prime Minister Boris Johnson and his party continue to average an 11-point lead which, if this holds until the election, would likely deliver a comfortable majority.Johnson can also point to other favourable metrics. When voters are asked who would make the ‘best prime minister’, a clear plurality (43%) say Johnson while only a small minority (20%) choose the Labour Party leader, Jeremy Corbyn. Polls also suggest that, on the whole, Johnson is more trusted by voters than Corbyn to deal with Brexit, the economy and crime, while Jeremy Corbyn only tends to enjoy leads on health. All of this lends credence to the claim that Britain could be set for a Conservative majority and, in turn, the passing of a withdrawal agreement bill in early 2020.But these polls also hide a lot of other shifts that are taking place and which, combined, make the 2019 general election unpredictable. One concerns leadership. While Boris Johnson enjoys stronger leadership ratings than Jeremy Corbyn, it should be remembered that what unites Britain’s current generation of party leaders is that they are all unpopular. Data compiled by Ipsos-MORI reveals that while Johnson has the lowest ratings of any new prime minister, Labour’s Jeremy Corbyn has the lowest ratings of any opposition leader since records began.Another deeper shift is fragmentation. One irony of Britain’s Brexit moment is that ever since the country voted to leave the European Union its politics have looked more ‘European’. Over the past year, one of the world’s most stable two-party systems has imploded into a four-party race, with the anti-Brexit Liberal Democrats and Nigel Farage’s strongly Eurosceptic Brexit Party both presenting a serious challenge to the two mainstream parties.In the latest polls, for example, Labour and the Conservatives are attracting only 61 per cent of the overall vote, well down on the 80 per cent they polled in 2017. Labour is weakened by the fact that it is only currently attracting 53 per cent of people who voted Labour at the last election, in 2017. A large number of these 2017 Labour voters, nearly one in four, have left for the Liberal Democrats, who are promising to revoke Article 50 and ‘cancel Brexit’. This divide in the Remain vote will produce unpredictable outcomes at the constituency level.Embed this image <img src="https://www.chathamhouse.org/sites/default/files/images/2019-11-07-Parliament.jpg" alt="The Houses of Parliament in autumn. Photo: Getty Images." title="The Houses of Parliament in autumn. Photo: Getty Images." />At the other end of the spectrum, the Conservatives are grappling with a similar but less severe threat. Nigel Farage and the Brexit Party are attracting around one in ten people who voted Conservative in 2017, which will make Boris Johnson’s task of capturing the crucial ‘Labour Leave’ seats harder. There is clear evidence that Johnson has been curbing Farage’s appeal, but it remains unclear how this rivalry on the right will play out from one seat to the next.One clue as to what happens next can be found in those leadership ratings. While 80 per cent of Brexit Party voters back Johnson over Corbyn, only 25 per cent of Liberal Democrat voters back Corbyn over Johnson. Johnson may find it easier to consolidate the Leave vote than Corbyn will find the task of consolidating the Remain vote.All of this reflects another reason why the election is unpredictable: volatility. This election is already Britain’s fifth nationwide election in only four years. After the 2015 general election, 2016 EU referendum, 2017 general election and 2019 European parliament elections, Britain’s political system and electorate have been in a state of almost continual flux. Along the way, a large number of voters have reassessed their loyalties.As the British Election Study makes clear, the current rate of ‘vote-switching’ in British politics, where people switch their vote from one election to the next, is largely unprecedented in the post-war era. Across the three elections held in 2010, 2015 and 2017, a striking 49 per cent of people switched their vote.This is not all about Brexit. Attachment to the main parties has been weakening since the 1960s. But Brexit is now accelerating this process as tribal identities as ‘Remainers’ or ‘Leavers’ cut across traditional party loyalties. All this volatility not only gives good reason to expect further shifts in support during the campaign but to also meet any confident predictions about the election result with a healthy dose of scepticism. Full Article
ic UK General Election 2019: Britain's New Foreign Policy Divide By feedproxy.google.com Published On :: Mon, 09 Dec 2019 12:12:50 +0000 9 December 2019 Thomas Raines Director, Europe Programme @TomHRaines Google Scholar A breakdown of foreign policy consensus means voters have a meaningful choice between two different visions of Britain’s place in the world. 2019-12-09-JohnsonCorbyn.jpg Boris Johnson and Jeremy Corbyn at the state opening of Parliament in October. Photo: Getty Images. Genuine ideological differences have returned to British politics. That is as true in foreign policy as in questions of domestic politics. The post-Cold War foreign policy consensus in UK politics around liberal multilateralism is fraying.This tradition had some key characteristics. It saw Britain as one of the cornerstones of an international order built on a liberal (or neo-liberal if you prefer) approach to economic globalization. EU membership was considered central to Britain’s influence and prosperity (even if further political integration never had deep support). Security policy was grounded in a stable package of NATO membership, close ties to the US, nuclear deterrence and a willingness to conduct military intervention.Both main parties accepted that foreign policy had a commercial dimension. Both were willing to sell arms abroad to regimes with dubious domestic records.Despite differences of emphasis, and some moments of genuine disagreement, foreign policy did not undergo big shifts as different parties traded periods in office. That may be set to change. Party dividesOn the one hand, Labour wants to reset and re-orientate Britain’s international role based on human rights and international law. It promises a new internationalism and to end what it glibly calls the ‘bomb first, talk later’ approach, alongside a human rights-driven trade policy. More concretely, it promises to legislate to ensure Parliament takes decisions on military action, boost resources for the underfunded Foreign Office and suspend arms sales to Saudi Arabia for use in Yemen. In Jeremy Corbyn, they have a leader with roots in a distinct left-wing ideological tradition of internationalism that blends a commitment to international solidarity alongside anti-imperial and anti-war sentiment. He has spent his career as a sharp critic of Israeli and US policy, while championing various international political causes, some more radical or fringe than others. His historic positions on issues like NATO and nuclear deterrence, while not represented in the party manifesto, demonstrate a personal radicalism that no recent Labour PM has embodied.His willingness to challenge the failures of the hitherto centre ground of foreign policy – particularly on military interventions from Iraq to Libya – is an under-appreciated aspect of his appeal among many supporters, even while it is one of the sharpest lines of attack from his critics. Boris Johnson’s chauvinistic rhetoric could not stand in sharper contrast to Labour’s commitment to conduct an audit of the effect of Britain’s colonial legacy on violence and insecurity. The Conservative manifesto asserts their pride in Britain’s historical role in the world, followed by a broad set of largely rhetorical commitments to bolster alliances and expand influence. An ambitious free trade agenda points to a more economic and commercially driven foreign policy, the inevitable trade-offs and constraints of which are only beginning to be addressed and debated.There is an underlying sense that Britain will be liberated from the constraints of EU membership, although beyond trade there is little that would not have been possible, or in most cases easier, from within the EU. As my colleague Richard Whitman has observed, the empty bromide ‘Global Britain’ has been dropped altogether, though beyond the idea of a new UK space command and a stronger sanctions regime, there is little that is new or specific. Not all the consensus centre-ground position has been abandoned. Both major parties remain committed to spending 2 per cent of GDP on defence and 0.7 per cent of gross national income on development in their 2019 manifestos.But beyond their manifesto commitments, prime ministers can exercise extensive powers in foreign affairs through the royal prerogative. Their government can choose to recognize other states, as Labour intends to do with Palestine. They can sign international treaties. And at present, in the absence of the sort of war powers act proposed by Labour, they can conduct military action without recourse to Parliament, which has no legally established role in this area.Even a weak minority government would have considerable scope to transform the tone of Britain’s diplomacy.Foreign policy as a partisan political issueIf UK foreign policy becomes more partisan, this will have longer term implications. Voters will theoretically have greater scope to shape and influence foreign policy more directly. Foreign policy may become divisive if it becomes more partisan. It may also become less consistent, which will affect the capacity of the UK to show leadership over the longer term on issues on which there is no domestic consensus. Britain’s allies may need to manage a less reliable partner. The diplomatic and security apparatus of Whitehall will need to be more adaptable. British elections generally don’t turn on foreign policy questions; 2019 will not buck that trend. At the same time, this election will be very influential in shaping Britain’s position on the world stage and its approach to international issues. Boris Johnson and Jeremy Corbyn represent very different ideas about Britain’s role: its foreign policy, its alliances, and indeed its idea of itself. The Brexit context makes these political undercurrents on foreign policy matter all the more.Foreign policy may not matter that much to most voters, but these elections matter for foreign policy. Full Article
ic Don’t Be Afraid of Political Fragmentation By feedproxy.google.com Published On :: Mon, 16 Dec 2019 11:00:17 +0000 16 December 2019 Pepijn Bergsen Research Fellow, Europe Programme @pbergsen LinkedIn If managed correctly, splintering and more volatile political systems – so-called ‘Dutchification’ – need not be a ticket to political and policy paralysis. 2019-12-16-Dutch-Election.jpg Voters cast their vote as part of the Dutch general elections on March 15, 2017 at a polling station in a mill in Oisterwijk. Photo by ROB ENGELAAR/AFP via Getty Images. In recent decades, political party systems across Europe have fragmented and electoral volatility has increased. The number of parties represented in parliaments across the continent has grown and the formerly dominant mainstream parties have seen their support base collapse, forcing parties into often uncomfortable and unstable coalitions.From the United Kingdom to Germany, politicians and commentators talk of such scenarios in often apocalyptic terms and associate it with political instability and policy paralysis.They shouldn’t. Instead they should focus their energy on making these increasingly competitive political markets work.The Netherlands is frequently held up as a prime example of this process, which is therefore sometimes referred to as ‘Dutchification’. Its highly proportional political system has created the opportunity for new parties and specific interest groups to win parliamentary representation, ranging from an animal rights party and a party catering specifically to the interests of the elderly.This has been accompanied by increased electoral volatility. In the 1970s, less than 15% of seats in the Dutch parliament would change party at any election, but in the last election in 2017, this was just over a quarter. The system also created space for the relatively early rise of populist far-right parties, though it was not the cause of their rise.Nevertheless, despite the regularly difficult coalition politics, it remains one of the most well-governed countries in the world.A short history of fragmentationLooking at the effective number of parties represented in parliaments, the number of parties, corrected for their size, provides a good measure of the extent of fragmentation. In the Netherlands this steadily increased from around four in the 1980s to over eight following the election in 2017. Even the populist far-right vote has fragmented, with two parties partly competing for the same electorate. In other countries it has been a more recent phenomenon. Spain remained a de facto two-party system until the financial crisis. Dissatisfaction with both mainstream parties has seen challenger parties on both the left and the right attract significant support, making it harder to form stable coalitions. Political fragmentation decreased slightly in Italy in recent years, but that was from a high base as it shot up in the early 1990s when the post-war political settlement crumbled.German politics, long a hallmark of stability, is struggling with the decrease in support for the parties that dominated its political scene in the post-war period. The Christian Democrats and Social Democrats only barely managed to win a majority together in the election in 2017, at 53.4% of the vote compared with the 81.3% achieved 30 years earlier. The latest polls suggest they would only get to 40% together if an election were held today.A similar trend is visible within the European Parliament. Whereas the two largest groups in the European Parliament, the Christian Democrats and the Social Democrats, together won 66% of the vote in the election in 1999, they did not even manage to win a majority together in 2019, taking just 39.5% of the vote.No crisis of democracyIf electoral volatility and political fragmentation does indeed constitute some sort of crisis of democracy, we should expect to see voters become unhappy about how their national democracy functions. Largely, the opposite seems to be the case.In the Netherlands, satisfaction with its democracy went up at the same time as Dutchification did its work. Similar trends are visible in other highly fragmented European political systems, often those with very proportional systems. Despite regular minority governments, satisfaction with democracy is above 90% in Denmark and at 80% in Sweden, according to the latest Eurobarometer data.In comparison, it stood at 52% in the United Kingdom and 53% in France, where the electoral system has, at least on the surface, prevented the kind of fragmentation supposedly plaguing proportional systems.Satisfaction with democracy seems to be affected by a number of factors. This includes the state of the economy, particularly in countries that were hit the hardest by the global financial and euro zone crises. Nevertheless, the data suggests that, even if we can’t say that Dutchification by definition leads to more satisfaction with democracy, it is clearly not associated with falling faith in the system.A competitive political marketDutchification should be seen as accompanying a more competitive political marketplace. A more emancipated, demanding and politically engaged electorate than in the post-war decades is willing to shop around instead of merely vote according to socioeconomic class or other dividing lines, such as religious ones. The fragmented parliaments that emerge as a result provide better representation of different groups within European societies.This makes life harder for Europe’s political parties and politicians, as they juggle large coalitions, or changing coalitions under minority governments, but provides voters with more choice and democratic renewal. If handled correctly this would also allow more responsiveness to shifts in public opinion.Such democratic creative destruction in competitive political markets is to be celebrated in a well-functioning democracy. Just as companies prefer to operate in an oligopoly, political parties prefer the stability of limited political competition. But wishing for this kind of stability comes perilously close to preferring stability over proper representation.Worrying about Dutchification risks confusing a crisis of the traditional mainstream parties with a crisis of democracy. For some countries, particularly those like the Netherlands and Denmark which have longer histories of consensus-based politics and coalition building, this is an easier adjustment. But this should not be an excuse to not attempt to make politics work better as they were forced to go through, arguably still ongoing, adjustment processes too.Instead of investing in futile attempts to get back to how things were in the old days, or hoping this will somehow magically happen, political leaders and parties across Europe need to reassess how they deal with the new reality of Dutchification. Full Article
ic Transatlantic Dialogue on China By feedproxy.google.com Published On :: Wed, 18 Dec 2019 09:32:30 +0000 A joint Chatham House-RUSI project that focuses on strengthening common understanding across the Atlantic and develop new ideas for how the US and Europe can better engage with and respond to China’s rise. This will be done through examining transatlantic approaches and responses to China through the lens for four key themes (digital technology; trade and investment; governance of global commons; and climate change and the environment) that have been identified as crucial to developing effective policy responses and fostering collaboration.The project will strengthen national, regional and international responses to the risks and opportunities posed by China’s changing role within the global economy and international rules-based order. Department contact Pepijn Bergsen Research Fellow, Europe Programme 020 795 75748 Email More on Transatlantic Dialogue on China Full Article
ic The EU Cannot Build a Foreign Policy on Regulatory Power Alone By feedproxy.google.com Published On :: Tue, 11 Feb 2020 16:33:26 +0000 11 February 2020 Alan Beattie Associate Fellow, Global Economy and Finance Programme and Europe Programme @alanbeattie LinkedIn Brussels will find its much-vaunted heft in setting standards cannot help it advance its geopolitical interests. 2020-02-11-Leyen.jpg EU Commission President Ursula von der Leyen speaks at the European Parliament in Strasbourg in February. Photo: Getty Images. There are two well-established ideas in trade. Individually, they are correct. Combined, they can lead to a conclusion that is unfortunately wrong.The first idea is that, across a range of economic sectors, the EU and the US have been engaged in a battle to have their model of regulation accepted as the global one, and that the EU is generally winning.The second is that governments can use their regulatory power to extend strategic and foreign policy influence.The conclusion would seem to be that the EU, which has for decades tried to develop a foreign policy, should be able to use its superpower status in regulation and trade to project its interests and its values abroad.That’s the theory. It’s a proposition much welcomed by EU policymakers, who know they are highly unlikely any time soon to acquire any of the tools usually required to run an effective foreign policy.The EU doesn’t have an army it can send into a shooting war, enough military or political aid to prop up or dispense of governments abroad, or a centralized intelligence service. Commission President Ursula von der Leyen has declared her outfit to be a ‘geopolitical commission’, and is casting about for any means of making that real.Through the ‘Brussels effect’ whereby European rules and standards are exported via both companies and governments, the EU has indeed won many regulatory battles with the US.Its cars, chemicals and product safety regulations are more widely adopted round the world than their American counterparts. In the absence of any coherent US offering, bar some varied state-level systems, the General Data Protection Regulation (GDPR) is the closest thing the world has to a single model for data privacy, and variants of it are being adopted by dozens of countries.The problem is this. Those parts of global economic governance where the US is dominant – particularly the dollar payments system – are highly conducive to projecting US power abroad. The extraterritorial reach of secondary sanctions, plus the widespread reliance of banks and companies worldwide on dollar funding – and hence the American financial system – means that the US can precisely target its influence.The EU can enforce trade sanctions, but not in such a powerful and discriminatory way, and it will always be outgunned by the US. Donald Trump could in effect force European companies to join in his sanctions on Iran when he pulled out of the nuclear deal, despite EU legislation designed to prevent their businesses being bullied. He can go after the chief financial officer of Huawei for allegedly breaching those sanctions.By contrast, the widespread adoption of GDPR or data protection regimes inspired by it may give the EU a warm glow of satisfaction, but it cannot be turned into a geopolitical tool in the same way.Nor, necessarily, does it particularly benefit the EU economy. Europe’s undersized tech sector seems unlikely to unduly benefit from the fact that data protection rules were written in the EU. Indeed, one common criticism of the regulations is that they entrench the power of incumbent tech giants like Google.There is a similar pattern at work in the adoption of new technologies such as artificial intelligence and the Internet of Things. In that field, the EU and its member states are also facing determined competition from China, which has been pushing its technologies and standards through forums such as the International Telecommunication Union.The EU has been attempting to write international rules for the use of AI which it hopes to be widely adopted. But again, these are a constraint on the use of new technologies largely developed by others, not the control of innovation.By contrast, China has created a vast domestic market in technologies like facial recognition and unleashed its own companies on it. The resulting surveillance kit can then be marketed to emerging market governments as part of China’s enduring foreign policy campaign to build up supporters in the developing world.If it genuinely wants to turn its economic power into geopolitical influence – and it’s not entirely clear what it would do with it if it did – the EU needs to recognize that not all forms of regulatory and trading dominance are the same.Providing public goods to the world economy is all very well. But unless they are so particular in nature that they project uniquely European values and interests, that makes the EU a supplier of useful plumbing but not a global architect of power.On the other hand, it could content itself with its position for the moment. It could recognize that not until enough hard power – guns, intelligence, money – is transferred from the member states to the centre, or until the member states start acting collectively, will the EU genuinely become a geopolitical force. Speaking loudly and carrying a stick of foam rubber is rarely a way to gain credibility in international relations.This article is part of a series of publications and roundtable discussions in the Chatham House Global Trade Policy Forum. Full Article
ic A Credit-fuelled Economic Recovery Stores Up Trouble for Turkey By feedproxy.google.com Published On :: Mon, 17 Feb 2020 13:47:40 +0000 17 February 2020 Fadi Hakura Consulting Fellow, Europe Programme LinkedIn Turkey is repeating the mistakes that led to the 2018 lira crisis and another freefall for the currency may not be far off. 2020-02-17-TurCB.jpg Headquarters of the Central Bank of the Republic of Turkey. Photo: Getty Images. Since the 2018 economic crisis, when the value of the lira plummeted and borrowing costs soared, Turkey’s economy has achieved a miraculous ‘V-shaped’ economic recovery from a recession lasting three quarters to a return back to quarterly growth above 1 per cent in the first three months of 2019.But this quick turnaround has been built on vast amounts of cheap credit used to re-stimulate a consumption and construction boom. This so-called ‘triple C’ economy generated a rapid growth spurt akin to a modestly able professional sprinter injected with steroids.This has made the currency vulnerable. The lira has steadily depreciated by 11 per cent against the US dollar since the beginning of 2019 and crossed the rate of 6 lira versus the US dollar on 7 February. And there are further warning signs on the horizon.Credit bonanzaStatistics reveal that Turkish domestic credit grew by around 13 per cent on average throughout 2019. The credit bonanza is still ongoing. Mortgage-backed home sales jumped by a record high of 600 per cent last December alone and the 2019 budget deficit catapulted by 70 per cent due to higher government spending.Turkey’s central bank fuelled this credit expansion by cutting interest rates aggressively to below inflation and, since the start of this year, purchasing lira-denominated bonds equivalent to around one-third of total acquisitions last year to push yields lower.Equally, it has linked bank lending to reserve requirements – the money that banks have to keep at the central bank – to boost borrowings via state and private banks. Banks with a ‘real’ loan growth (including inflation) of between 5 and 15 per cent enjoy a 2 per cent reserve ratio on most lira deposits, which authorities adjusted from an earlier band of 10-20 per cent that did not consider double-digit inflation.Cumulatively, bond purchases (effectively quantitative easing) and reserve management policies have also contributed to eased credit conditions.Commercial banks have also reduced deposit rates on lira accounts to less than inflation to encourage consumption over saving. Together with low lending rates, the boost to the economy has flowed via mortgages, credit card loans, vehicle leasing transactions and general business borrowings.Accordingly, stimulus is at the forefront of the government’s economic approach, as it was in 2017 and 2018. It does not seem to be implementing structural change to re-orient growth away from consumption towards productivity. In addition, governance is, again, a central issue. President Recep Tayyip Erdogan’s near total monopolization of policymaking means he guides all domestic and external policies. He forced out the previous central bank governor, Murat Cetinkaya, in July 2019 because he did not share the president’s desire for an accelerated pace of interest rate reductions.New challengesDespite the similarities, the expected future financial turbulence will be materially different from its 2018 predecessor in four crucial respects. Firstly, foreign investors will only be marginally involved. Turkey has shut out foreign investors since 2018 from lira-denominated assets by restricting lira swap arrangements. Unsurprisingly, the non-resident holdings of lira bonds has plummeted from 20 per cent in 2018 to less than 10 per cent today.Secondly, the Turkish government has recently introduced indirect domestic capital controls by constraining most commercial transactions to the lira rather than to the US dollar or euro to reduce foreign currency demand in light of short-term external debt obligations of $191 billion.Thirdly, the Turkish state banks are intervening quite regularly to soften Lira volatility, thereby transitioning from a ‘free float’ to a ‘managed float’. So far, they have spent over $37 billion over the last two years in a futile effort to buttress the lira. This level of involvement in currency markets cannot be maintained.Fourthly, the Turkish state is being far more interventionist in the Turkish stock exchange and bond markets to keep asset prices elevated. Government-controlled local funds have participated in the Borsa Istanbul and state banks in sovereign debt to sustain rallies or reverse a bear market. All these measures have one running idea: exclude foreign investors and no crisis will recur. Yet, when the credit boom heads to a downturn sooner or later, Turks will probably escalate lira conversions to US dollars; 51 per cent of all Turkish bank deposits are already dollar-denominated and the figure is still rising.If Turkey’s limited foreign reserves cannot satisfy the domestic dollar demand, the government may have to impose comprehensive capital controls and allow for a double digit depreciation in the value of the lira to from its current level, with significant repercussions on Turkey’s political stability and economic climate.To avoid this scenario, it needs to restore fiscal and monetary prudence, deal the with the foreign debt overhang in the private sector and focus on productivity-improving economic and institutional reforms to gain the confidence of global financial markets and Turks alike. Full Article
ic POSTPONED: Is a 'Geopolitical' Europe Possible? By feedproxy.google.com Published On :: Thu, 05 Mar 2020 10:10:01 +0000 Invitation Only Research Event 25 March 2020 - 8:30am to 9:30am Chatham House | 10 St James's Square | London | SW1Y 4LE Event participants Michael Karnitschnig, Director for External Relations, Secretariat-General, European Commission What role does the EU want to play in a world characterised increasingly by power politics? The new European Commission has explicitly stated its ambition for the EU to become a stronger geopolitical actor. Is it capable of becoming a third pole in an enduring US-China stand-off?From climate change to trade policy and security, the next 5 years may prove decisive in proving the EU can be a strong player both in its neighbourhood and globally. Given what is at stake, what are the Commission’s strategic and policymaking priorities for the next five years? With the discussions on the future EU budget ongoing, what areas will be prioritized when member states come to make decisions between competing objectives? Does the way the EU is perceived externally depend on its member states’ ability to put on a united front when it comes to the most pressing global challenges?Finally, is this ambitious geopolitical vision deliverable within the EU’s existing structures? If not, are member states ready to give up more control for a stronger Europe at the EU level?PLEASE NOTE THIS EVENT IS POSTPONED UNTIL FURTHER NOTICE. Event attributes Chatham House Rule Department/project Europe Programme, Britain and Europe: The Post-Referendum Agenda Alina Lyadova Europe Programme Coordinator Email Full Article
ic Biochemical and structural insights into how amino acids regulate pyruvate kinase muscle isoform 2 [Enzymology] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Pyruvate kinase muscle isoform 2 (PKM2) is a key glycolytic enzyme involved in ATP generation and critical for cancer metabolism. PKM2 is expressed in many human cancers and is regulated by complex mechanisms that promote tumor growth and proliferation. Therefore, it is considered an attractive therapeutic target for modulating tumor metabolism. Various stimuli allosterically regulate PKM2 by cycling it between highly active and less active states. Several small molecules activate PKM2 by binding to its intersubunit interface. Serine and cysteine serve as an activator and inhibitor of PKM2, respectively, by binding to its amino acid (AA)-binding pocket, which therefore represents a potential druggable site. Despite binding similarly to PKM2, how cysteine and serine differentially regulate this enzyme remains elusive. Using kinetic analyses, fluorescence binding, X-ray crystallography, and gel filtration experiments with asparagine, aspartate, and valine as PKM2 ligands, we examined whether the differences in the side-chain polarity of these AAs trigger distinct allosteric responses in PKM2. We found that Asn (polar) and Asp (charged) activate PKM2 and that Val (hydrophobic) inhibits it. The results also indicate that both Asn and Asp can restore the activity of Val-inhibited PKM2. AA-bound crystal structures of PKM2 displayed distinctive interactions within the binding pocket, causing unique allosteric effects in the enzyme. These structure-function analyses of AA-mediated PKM2 regulation shed light on the chemical requirements in the development of mechanism-based small-molecule modulators targeting the AA-binding pocket of PKM2 and provide broader insights into the regulatory mechanisms of complex allosteric enzymes. Full Article
ic Evolution, expression, and substrate specificities of aldehyde oxidase enzymes in eukaryotes [Enzymology] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Aldehyde oxidases (AOXs) are a small group of enzymes belonging to the larger family of molybdo-flavoenzymes, along with the well-characterized xanthine oxidoreductase. The two major types of reactions that are catalyzed by AOXs are the hydroxylation of heterocycles and the oxidation of aldehydes to their corresponding carboxylic acids. Different animal species have different complements of AOX genes. The two extremes are represented in humans and rodents; whereas the human genome contains a single active gene (AOX1), those of rodents, such as mice, are endowed with four genes (Aox1-4), clustering on the same chromosome, each encoding a functionally distinct AOX enzyme. It still remains enigmatic why some species have numerous AOX enzymes, whereas others harbor only one functional enzyme. At present, little is known about the physiological relevance of AOX enzymes in humans and their additional forms in other mammals. These enzymes are expressed in the liver and play an important role in the metabolisms of drugs and other xenobiotics. In this review, we discuss the expression, tissue-specific roles, and substrate specificities of the different mammalian AOX enzymes and highlight insights into their physiological roles. Full Article
ic The heme-regulatory motifs of heme oxygenase-2 contribute to the transfer of heme to the catalytic site for degradation [Protein Structure and Folding] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Heme-regulatory motifs (HRMs) are present in many proteins that are involved in diverse biological functions. The C-terminal tail region of human heme oxygenase-2 (HO2) contains two HRMs whose cysteine residues form a disulfide bond; when reduced, these cysteines are available to bind Fe3+-heme. Heme binding to the HRMs occurs independently of the HO2 catalytic active site in the core of the protein, where heme binds with high affinity and is degraded to biliverdin. Here, we describe the reversible, protein-mediated transfer of heme between the HRMs and the HO2 core. Using hydrogen-deuterium exchange (HDX)-MS to monitor the dynamics of HO2 with and without Fe3+-heme bound to the HRMs and to the core, we detected conformational changes in the catalytic core only in one state of the catalytic cycle—when Fe3+-heme is bound to the HRMs and the core is in the apo state. These conformational changes were consistent with transfer of heme between binding sites. Indeed, we observed that HRM-bound Fe3+-heme is transferred to the apo-core either upon independent expression of the core and of a construct spanning the HRM-containing tail or after a single turnover of heme at the core. Moreover, we observed transfer of heme from the core to the HRMs and equilibration of heme between the core and HRMs. We therefore propose an Fe3+-heme transfer model in which HRM-bound heme is readily transferred to the catalytic site for degradation to facilitate turnover but can also equilibrate between the sites to maintain heme homeostasis. Full Article
ic An enzyme-based protocol for cell-free synthesis of nature-identical capsular oligosaccharides from Actinobacillus pleuropneumoniae serotype 1 [Enzymology] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 Actinobacillus pleuropneumoniae (App) is the etiological agent of acute porcine pneumonia and responsible for severe economic losses worldwide. The capsule polymer of App serotype 1 (App1) consists of [4)-GlcNAc-β(1,6)-Gal-α-1-(PO4-] repeating units that are O-acetylated at O-6 of the GlcNAc. It is a major virulence factor and was used in previous studies in the successful generation of an experimental glycoconjugate vaccine. However, the application of glycoconjugate vaccines in the animal health sector is limited, presumably because of the high costs associated with harvesting the polymer from pathogen culture. Consequently, here we exploited the capsule polymerase Cps1B of App1 as an in vitro synthesis tool and an alternative for capsule polymer provision. Cps1B consists of two catalytic domains, as well as a domain rich in tetratricopeptide repeats (TPRs). We compared the elongation mechanism of Cps1B with that of a ΔTPR truncation (Cps1B-ΔTPR). Interestingly, the product profiles displayed by Cps1B suggested processive elongation of the nascent polymer, whereas Cps1B-ΔTPR appeared to work in a more distributive manner. The dispersity of the synthesized products could be reduced by generating single-action transferases and immobilizing them on individual columns, separating the two catalytic activities. Furthermore, we identified the O-acetyltransferase Cps1D of App1 and used it to modify the polymers produced by Cps1B. Two-dimensional NMR analyses of the products revealed O-acetylation levels identical to those of polymer harvested from App1 culture supernatants. In conclusion, we have established a protocol for the pathogen-free in vitro synthesis of tailored, nature-identical App1 capsule polymers. Full Article
ic Specificity and affinity of the N-terminal residues in staphylocoagulase in binding to prothrombin [Computational Biology] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 In Staphylococcus aureus–caused endocarditis, the pathogen secretes staphylocoagulase (SC), thereby activating human prothrombin (ProT) and evading immune clearance. A previous structural comparison of the SC(1–325) fragment bound to thrombin and its inactive precursor prethrombin 2 has indicated that SC activates ProT by inserting its N-terminal dipeptide Ile1-Val2 into the ProT Ile16 pocket, forming a salt bridge with ProT's Asp194, thereby stabilizing the active conformation. We hypothesized that these N-terminal SC residues modulate ProT binding and activation. Here, we generated labeled SC(1–246) as a probe for competitively defining the affinities of N-terminal SC(1–246) variants preselected by modeling. Using ProT(R155Q,R271Q,R284Q) (ProTQQQ), a variant refractory to prothrombinase- or thrombin-mediated cleavage, we observed variant affinities between ∼1 and 650 nm and activation potencies ranging from 1.8-fold that of WT SC(1–246) to complete loss of function. Substrate binding to ProTQQQ caused allosteric tightening of the affinity of most SC(1–246) variants, consistent with zymogen activation through occupation of the specificity pocket. Conservative changes at positions 1 and 2 were well-tolerated, with Val1-Val2, Ile1-Ala2, and Leu1-Val2 variants exhibiting ProTQQQ affinity and activation potency comparable with WT SC(1–246). Weaker binding variants typically had reduced activation rates, although at near-saturating ProTQQQ levels, several variants exhibited limiting rates similar to or higher than that of WT SC(1–246). The Ile16 pocket in ProTQQQ appears to favor nonpolar, nonaromatic residues at SC positions 1 and 2. Our results suggest that SC variants other than WT Ile1-Val2-Thr3 might emerge with similar ProT-activating efficiency. Full Article