Laboratoire dExcellence GR Ex

Paris, France

Laboratoire dExcellence GR Ex

Paris, France

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Yurenko Y.P.,Masaryk University | Bazzi S.,German Electron Synchrotron | Bazzi S.,University of Hamburg | Marek R.,Masaryk University | And 5 more authors.
Chemistry - A European Journal | Year: 2017

Anion–π interactions have been shown to stabilize flavoproteins and to regulate the redox potential of the flavin cofactor. They are commonly attributed to electrostatic forces. Herein we show that anion–flavin interactions can have a substantial charge-transfer component. Our conclusion emanates from a multi-approach theoretical analysis and is backed by previously reported observations of absorption bands, originating from charge transfer between oxidized flavin and proximate cysteine thiolate groups. This partial covalency of anion–flavin contacts renders classical simulations of flavoproteins questionable. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim


Alkindi S.S.,Sultan Qaboos University | Alzadjali S.,Sultan Qaboos University | Daar S.,Sultan Qaboos University | Sindhuvi E.,Christian Medical College Hospital | And 8 more authors.
European Journal of Haematology | Year: 2013

Introduction: Coinheritance of α-thalassemia influences the clinical and hematological phenotypes of β-hemoglobinopathies (β-thalassemia and sickle cell disease) and when present together in significant frequency within a population, a spectrum of clinical forms is observed. Precise molecular characterization of α-thalassemia is important in understanding their disease-modifying role in β-hemoglobinopathies and for diagnostic purposes. Patients and methods: Because currently used approaches are labor/cost-intensive, time-consuming, error-prone in certain genotype combinations and not applicable for large epidemiological screening, we developed a systematic stepwise strategy to overcome these difficulties. We successfully applied this to characterize the α-globin gene status in 150 Omani cord blood samples with Hb Barts and 32 patients with HbH disease. Results: We observed a good correlation between α-globin genotypes and level of Hb Bart's with the Hb Bart's levels significantly higher in both deletional and non-deletional α-globin genotypes. The most common α-globin genotype in HbH cases was αTSaudiα/αTSaudiα (n = 16; 50%) followed by -α3.7/-MED (n = 10; 31%). This approach detects also the α-globin gene triplication as exemplified by the study of a family where the β-globin gene defect failed to explain the β-thalassemia intermedia phenotype. Conclusion: Molecular characterization of α-thalassemia is complex due to high sequence homology between the duplicated α-globin genes and to the existence of a variety of gene rearrangements (small and large deletions of various sizes) and punctual substitutions (non-deletional alleles). The novelty of our strategy resides, not in the individual technical steps per se but in the reasoned sequential order of their use taking into consideration the hematological phenotype as well. © 2013 John Wiley & Sons A/S.


De Falco L.,Ceinge | Sanchez M.,Institute of Predictive and Personalized Medicine of Cancer IMPPC | Sanchez M.,Institute Dinvestigacio En Ciencies Of La Salut Germans Trias I Pujol Igtp | Silvestri L.,San Raffaele Scientific Institute | And 12 more authors.
Haematologica | Year: 2013

Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. © 2013 Ferrata Storti Foundation.


PubMed | University of Pécs, CNRS Systems and Applications of Information Technologies and Energy Laboratory, Laboratoire dExcellence GR Ex, French Institute of Health and Medical Research and CHU de Pointe a Pitre
Type: Clinical Trial, Phase III | Journal: British journal of haematology | Year: 2016

Vaso-occlusive crisis (VOC) is the main acute complication in sickle cell anaemia (SS) and several clinical trials are investigating different drugs to improve the clinical severity of SS patients. A phase III study is currently exploring the profit of Velopoloxamer in SS during VOCs. We analysed, in-vitro, the effect of poloxamer (P188) on red blood cell (RBC) properties by investigating haemorheology, mechanical and adhesion functions using ektacytometry, microfluidics and dynamic adhesion approaches, respectively. We show that poloxamer significantly reduces blood viscosity, RBC aggregation and adhesion to endothelial cells, supporting the beneficial use of this molecule in SS therapy.


Schneider B.,Academy of Sciences of the Czech Republic | Cerny J.,Academy of Sciences of the Czech Republic | Svozil D.,Institute of Chemical Technology Prague | Cech P.,Institute of Chemical Technology Prague | And 8 more authors.
Nucleic Acids Research | Year: 2014

To investigate the principles driving recognition between proteins and DNA, we analyzed more than thousand crystal structures of protein/DNA complexes. We classified protein and DNA conformations by structural alphabets, protein blocks [de Brevern, Etchebest and Hazout (2000) (Bayesian probabilistic approach for predicting backbone structures in terms of protein blocks. Prots. Struct. Funct. Genet., 41:271-287)] and dinucleotide conformers [Svozil, Kalina, Omelka and Schneider (2008) (DNA conformations and their sequence preferences. Nucleic Acids Res., 36:3690-3706)], respectively. Assembling the mutually interacting protein blocks and dinucleotide conformers into 'interaction matrices' revealed their correlations and conformer preferences at the interface relative to their occurrence outside the interface. The analyzed data demonstrated important differences between complexes of various types of proteins such as transcription factors and nucleases, distinct interaction patterns for the DNA minor groove relative to the major groove and phosphate and importance of water-mediated contacts. Water molecules mediate proportionally the largest number of contacts in the minor groove and form the largest proportion of contacts in complexes of transcription factors. The generally known induction of A-DNA forms by complexation was more accurately attributed to A-like and intermediate A/B conformers rare in naked DNA molecules. © The Author(s) 2013.


Moulouel B.,University Paris Diderot | Houamel D.,University Paris Diderot | Delaby C.,University Paris Diderot | Tchernitchko D.,University Paris Diderot | And 13 more authors.
Kidney International | Year: 2013

Hepcidin, the key regulatory hormone of iron homeostasis, and iron carriers such as transferrin receptor1 (TFR1), divalent metal transporter1 (DMT1), and ferroportin (FPN) are expressed in kidney. Whether hepcidin plays an intrinsic role in the regulation of renal iron transport is unknown. Here, we analyzed the renal handling of iron in hemochromatosis Hepc-/- and Hjv -/- mouse models, as well as in phenylhydrazine (PHZ)-treated mice. We found a marked medullary iron deposition in the kidneys of Hepc-/- mice, and iron leak in the urine. The kidneys of Hepc-/- mice exhibited a concomitant decrease in TFR1 and increase in ferritin and FPN expression. Increased FPN abundance was restricted to the thick ascending limb (TAL). DMT1 protein remained unaffected despite a significant decrease of its mRNA level, suggesting that DMT1 protein is stabilized in the absence of hepcidin. Treatment of kidney sections from Hepc-/- mice with hepcidin decreased DMT1 protein, an effect confirmed in renal cell lines where hepcidin markedly decreased 55 Fe transport. In the kidneys of Hjv-/- mice exhibiting low hepcidin expression, the iron overload was similar to that in the kidneys of Hepc-/- mice. However, in PHZ mice, iron accumulation resulting from hemoglobin leak was detected in the proximal tubule. Thus, kidneys exhibit a tissue-specific handling of iron that depends on the extra iron source. Hepcidin may control the expression of iron transporters to prevent renal iron overload. © 2013 International Society of Nephrology.


Schneider B.,Academy of Sciences of the Czech Republic | Gelly J.-C.,French Institute of Health and Medical Research | Gelly J.-C.,University Paris Diderot | Gelly J.-C.,Sanguine | And 6 more authors.
Acta Crystallographica Section D: Biological Crystallography | Year: 2014

The dynamics of protein and nucleic acid structures is as important as their average static picture. The local molecular dynamics concealed in diffraction images is expressed as so-called B factors. To find out how the crystal-derived B factors represent the dynamic behaviour of atoms and residues of proteins and DNA in their complexes, the distributions of scaled B factors from a carefully curated data set of over 700 protein-DNA crystal structures were analyzed [Schneider et al. (2014), Nucleic Acids Res. 42, 3381-3394]. Amino acids and nucleotides were categorized based on their molecular neighbourhood as solvent-accessible, solvent-inaccessible (i.e. forming the protein core) or lying at protein-protein or protein-DNA interfaces; the backbone and side-chain atoms were analyzed separately. The B factors of two types of crystal-ordered water molecules were also analyzed. The analysis confirmed several expected features of protein and DNA dynamics, but also revealed surprising facts. Solvent-accessible amino acids have B factors that are larger than those of residues at the biomolecular interfaces, and core-forming amino acids are the most restricted in their movement. A unique feature of the latter group is that their side-chain and backbone atoms are restricted in their movement to the same extent; in all other amino-acid groups the side chains are more floppy than the backbone. The low values of the B factors of water molecules bridging proteins with DNA and the very large fluctuations of DNA phosphates are surprising. The features discriminating different types of residues are less pronounced in structures with lower crystallographic resolution. Some of the observed trends are likely to be the consequence of improper refinement protocols that may need to be rectified. © 2014 International Union of Crystallography.


PubMed | Laboratoire DExcellence GR Ex, Unite de Securite Transfusionnelle et dHemovigilance, Sanguine, Etablissement Francais du Sang and 2 more.
Type: Case Reports | Journal: Transfusion | Year: 2016

Delayed hemolytic transfusion reaction (DHTR) is a life-threatening condition in sickle cell disease (SCD) patients that is frequently complicated by hyperhemolysis. Antibodies resulting from antigen disparity between donors of European ancestry and patients of African ancestry are common, but situations involving antibodies not classically of clinical significance are also encountered. Anti-HI is generally considered to be an innocuous naturally occurring antibody.We describe two cases of hyperhemolysis with anti-HI and provide details of the reported cases.Both SCD patients were polyimmunized and belonged to blood group B. They developed anti-HI that was reactive at 37C, after the transfusion of group O red blood cell units matched for all known and produced antibodies classically considered to be clinically significant. Both patients developed DHTR with hyperhemolysis. In the first case, a pregnant woman, a second transfusion was unavoidable and the patient died from cardiac arrest. The state of the second patient improved without the need for further transfusion.Three other cases of DHTR with anti-HI have been described in the literature in SCD patients. The two additional cases reported here definitively demonstrate that anti-HI is dangerous in SCD patients. As a result, ABO-identical matching (including A1 status) must be considered in SCD patients with anti-HI.


Bhaskara R.M.,Indian Institute of Science | De Brevern A.G.,French Institute of Health and Medical Research | De Brevern A.G.,University Paris Diderot | De Brevern A.G.,Laboratoire DExcellence GR Ex | Srinivasan N.,Indian Institute of Science
Journal of Biomolecular Structure and Dynamics | Year: 2013

Inter-domain linkers (IDLs) bridge flanking domains and support inter-domain communication in multi-domain proteins. Their sequence and conformational preferences enable them to carry out varied functions. They also provide sufficient flexibility to facilitate domain motions and, in conjunction with the interacting interfaces, they also regulate the inter-domain geometry (IDG). In spite of the basic intuitive understanding of the inter-domain orientations with respect to linker conformations and interfaces, we still do not entirely understand the precise relationship among the three. We show that IDG is evolutionarily well conserved and is constrained by the domain-domain interface interactions. The IDLs modulate the interactions by varying their lengths, conformations and local structure, thereby affecting the overall IDG. Results of our analysis provide guidelines in modelling of multi-domain proteins from the tertiary structures of constituent domain components. © 2013 Taylor & Francis.


Da Costa L.,AP HP | Da Costa L.,University Paris Diderot | Da Costa L.,French Institute of Health and Medical Research | Da Costa L.,Laboratoire dExcellence GR Ex | And 3 more authors.
Blood Reviews | Year: 2013

Hereditary spherocytosis and elliptocytosis are the two most common inherited red cell membrane disorders resulting from mutations in genes encoding various red cell membrane and skeletal proteins. Red cell membrane, a composite structure composed of lipid bilayer linked to spectrin-based membrane skeleton is responsible for the unique features of flexibility and mechanical stability of the cell. Defects in various proteins involved in linking the lipid bilayer to membrane skeleton result in loss in membrane cohesion leading to surface area loss and hereditary spherocytosis while defects in proteins involved in lateral interactions of the spectrin-based skeleton lead to decreased mechanical stability, membrane fragmentation and hereditary elliptocytosis. The disease severity is primarily dependent on the extent of membrane surface area loss. Both these diseases can be readily diagnosed by various laboratory approaches that include red blood cell cytology, flow cytometry, ektacytometry, electrophoresis of the red cell membrane proteins, and mutational analysis of gene encoding red cell membrane proteins. © 2013 Elsevier Ltd.

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