Vicente García, Vicente

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Vicente García, Vicente

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Vicente García, Vicente

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Universidad de Murcia. Departamento de Medicina

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Role of the C-sheet in the maturation of N-glycans on antithrombin: functional relevance of pleiotropic mutations
(2014-04-15) Águila Martínez, Sonia; Navarro Fernández, José Luis; Bohdan, N.; Gutiérrez Gallego, R.; Morena Barrio, María Eugenia de la; Vicente García, Vicente; Corral de la Calle, Javier; Martínez-Martínez, I.; Medicina Interna; Facultad de Medicina
Open Access
Neutrophil extracellular traps and von Willebrand factor are allies that negatively influence COVID-19 outcomes
(Wiley, 2021-01) Águila Martínez, Sonia; Fernández-Pérez, M. P.; Reguilón-Gallego, L.; de Los Reyes-García, A. M.; Miñano, A.; Bravo-Pérez, C.; García-Barberá, N.; Gómez-Verdú, J. M.; Martínez, C.; Morena Barrio, María Eugenia de la; Corral de la Calle, Javier; Bernal Morell, Enrique; Herranz Marín, María Teresa; Vicente García, Vicente; González-Conejero Hilla, Rocío; Lozano Almela, María Luisa; Medicina Interna
Open Access
N-Glycosylation as a Tool to Study Antithrombin Secretion, Conformation, and Function.
(MDPI, 2021-06-06) Águila Martínez, Sonia; Noto, Rosina; Luengo-Gil, Ginés; Espín, Salvador; Bohdan, Nataliya; Morena Barrio, María Eugenia de la; Peñas, Julia; Rodenas, Maria Carmen; Vicente García, Vicente; Corral de la Calle, Javier; Manno, Mauro; Martínez-Martínez, Irene; Medicina Interna
N-linked glycosylation is a crucial post-translational modification involved in protein folding, function, and clearance. N-linked glycosylation is also used therapeutically to enhance the half-lives of many proteins. Antithrombin, a serpin with four potential N-glycosylation sites, plays a pivotal role in hemostasis, wherein its deficiency significantly increases thrombotic risk. In this study, we used the introduction of N-glycosylation sites as a tool to explore what effect this glycosylation has on the protein folding, secretion, and function of this key anticoagulant. To accomplish this task, we introduced an additional N-glycosylation sequence in each strand. Interestingly, all regions that likely fold rapidly or were surrounded by lysines were not glycosylated even though an Nglycosylation sequon was present. The new sequon in the strands of the A- and B-sheets reduced secretion, and the B-sheet was more sensitive to these changes. However, the mutations in the strands of the C-sheet allowed correct folding and secretion, which resulted in functional variants. Therefore, our study revealed crucial regions for antithrombin secretion and could potentially apply to all serpins. These results could also help us understand the functional effects of natural variants causing type-I deficiencies.
Open Access
Novel loci involved on platelet function and platelet count identified by a genome-wide study performed in children
(Ferrata Storti Foundation, 2011-09) Guerrero López, José Antonio; Rivera Pozo, José; Quiroga, Teresa; Martínez Pérez, Ángel; Antón, Ana Isabel; Martínez, Constantino; Panes, Olga; Vicente García, Vicente; Mezzano, Diego; Soria, José Manuel; Corral de la Calle, Javier; Medicina Interna
Background Genome-wide association studies are currently identifying new loci with potential roles in thrombosis and hemostasis: these loci include novel polymorphisms associated with platelet function traits and count. However, no genome-wide study performed on children has been reported to date, in spite of the potential that these subjects have in genetic studies, when compared to adults, given the minimal degree of confounders, i.e., acquired and environmental factors, such as smoking, physical activity, diet, and drug or hormone intake, which are particularly important in platelet function.Design and Methods To identify new genetic variants involved in platelet reactivity and count, we performed a genome-wide association study on 75 children (8.5±1.8 years) using the Illumina Sentrix Human CNV370-Quad BeadChip containing 320,610 single nucleotide polymorphisms. Functional analyses included assessment of platelet aggregation and granule secretion triggered by different agonists (arachidonic acid, collagen, epinephrine, ADP), as well as platelet count. Associations were selected based on statistical significance and physiological relevance for a subsequent replication study in a similar sample of 286 children.Results We confirmed previously established associations with plasma levels of factors XII, VII and VIII as well as associations with platelet responses to ADP. Additionally, we identified 82 associations with platelet reactivity and count with a P value less than 10−5. From the associations selected for further replication, we validated two single nucleotide polymorphisms with mildly increased platelet reactivity (rs4366150 and rs1787566) on the LPAR1 and MYO5B genes, encoding lisophosphatidic acid receptor-1 and myosin VB, respectively; and rs1937970, located on the NRG3 gene coding neuroregulin-3, associated with platelet count.Conclusions Our genome-wide association study performed in children, followed by a validation analysis, led us to the identification of new genes potentially relevant in platelet function and biogenesis.
Open Access
Amelioration of the severity of heparin-binding antithrombin mutations by posttranslational mosaicism
(American Society of Hematology, 2012-04-12) Martínez-Martínez, Irene; Navarro-Fernández, José; Ostergaad, Alice; Gutierrez-Gallego, Ricardo; Padilla, José; Miñano, Antonia; Pascual, Cristina; Martínez, Constantino; Morena-Barrio, María Eugenia de la; Pedersen, Shona; Kristensen, Soren Risom; Corral, Javier; Bohdan, Nataliya; Morena Barrio, María Eugenia de la; Águila Martínez, Sonia; Vicente García, Vicente; Corral de la Calle, Javier; Medicina
The balance between actions of procoagulant and anticoagulant factors protects organisms from bleeding and thrombosis. Thus, antithrombin deficiency increases the risk of thrombosis, and complete quantitative deficiency results in intrauterine lethality. However, patients homozygous for L99F or R47C antithrombin mutations are viable. These mutations do not modify the folding or secretion of the protein, but abolish the glycosaminoglycan-induced activation of antithrombin by affecting the heparin-binding domain. We speculated that the natural β-glycoform of antithrombin might compensate for the effect of heparin-binding mutations. We purified α- and β-antithrombin glycoforms from plasma of 2 homozygous L99F patients. Heparin affinity chromatography and intrinsic fluorescence kinetic analyses demonstrated that the reduced heparin affinity of the α-L99F glycoform (K(D), 107.9 ± 3nM) was restored in the β-L99F glycoform (K(D), 53.9 ± 5nM) to values close to the activity of α-wild type (K(D), 43.9 ± 0.4nM). Accordingly, the β-L99F glycoform was fully activated by heparin. Similar results were observed for recombinant R47C and P41L, other heparin-binding antithrombin mutants. In conclusion, we identified a new type of mosaicism associated with mutations causing heparin-binding defects in antithrombin. The presence of a fully functional β-glycoform together with the activity retained by these variants helps to explain the viability of homozygous and the milder thrombotic risk of heterozygous patients with these specific antithrombin
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Genetic variants of the extra-large stimulatory Gs protein alpha-subunit and risk of thrombotic and haemorrhagic disorders
(Wiley, 2004-04-27) González-Conejero Hilla, Rocío; Corral de la Calle, Javier; Guerrero López, José Antonio; Iniesta Valera, Juan Antonio; Rivera Pozo, José; Arriba de la Fuente, Felipe de; Vicente García, Vicente; Medicina Interna
A polymorphism of the gene encoding the extra-large stimulatory G-protein a-subunit (XLas), originally identified in three patients with a bleeding tendency, involved a 36-bp insertion and two missense changes. A paternallyinherited insertion displayed a moderate platelet Gsa over-expression, which lead to platelet hypo-reactivity. These data prompted us to investigate the genetic, functional and clinical relevance of this polymorphism in the Mediterranean population. We included 414 healthy subjects and three case/ control studies: 263 consecutive patients with a first episode of primary intracerebral haemorrhage, 195 patients with deep venous thrombosis, and 104 patients with cerebrovascular disease. Controls were selected by approximating criteria to match selected risk factors to patients. Moreover, we performed studies of platelet function. We developed a simple method to determine the methylated allele, by digestion of genomic DNA with Sma I before polymerase chain reaction amplification. We identified two new rare variants, resulting from the loss of repeat units 7 and 5. The AB genotype was present in 3Æ6% of healthy population and the prevalence of the B allele was similar among cases and controls. Accordingly, the non-methylated B allele did not modify either the expression of platelet Gsa or the platelet response to Gs-agonists. Thus, our study suggests a minor functional role of XLas polymorphism in thrombotic or in haemorrhagic disorders.
Open Access
Disease-causing mutations in the serpin antithrombin reveal a keydomaincritical for inhibiting protease activities
(Elsevier, American Society for Biochemistry and Molecular Biology , 2017-10-06) Águila Martínez, Sonia; Izaguirre, G.; Vicente García, Vicente; Martínez-Martínez, I.; Olson, S. T.; Corral de la Calle, Javier; Medicina Interna
Antithrombin mainly inhibits factor Xa and thrombin. The reactive center loop (RCL) is crucial for its interactions with its protease targets and is fully inserted into the A-sheet after its cleavage, causing translocation of the covalently linked protease to the opposite end of the A-sheet. Antithrombin variants with altered RCL hinge residues behave as substrates rather than inhibitors, resulting in stoichiometries of inhibition greater than one. Other antithrombin residues have been suggested to interfere with RCL insertion or the stability of the antithrombin–protease complex, but available crystal structures or mutagenesis studies have failed to identify such residues. Here, we characterized two mutations, S365L and I207T, present in individuals with type II antithrombin deficiency and identified a new antithrombin functional domain. S365L did not form stable complexes with thrombin or factor Xa, and the I207T/I207A variants inhibited both proteases with elevated stoichiometries of inhibition. Close proximity of Ile-207 and Ser-365 to the inserted RCL suggested that the preferred reaction of these mutants as protease substrates reflects an effect on the rate of the RCL insertion and protease translocation. However, both residues lie within the final docking site for the protease in the antithrombin–protease complex, supporting the idea that the enhanced substrate reactions may result from an increased dissociation of the final complexes. Our findings demonstrate that the distal end of the antithrombin A-sheet is crucial for the last steps of protease inhibition either by affecting the rate of RCL insertion or through critical interactions with proteases at the end of the A-sheet.
Open Access
Flavonoids inhibit the platelet TxA2 signalling pathway and antagonize TxA2 receptors (TP) in platelets and smooth muscle cells
(Wiley, British Pharmacological Society, 2007-04-10) Guerrero López, José Antonio; Navarro-Nuñez, Leyre; Lozano Almela, María Luisa; Martínez, Constantino; Vicente García, Vicente; Gibbins, Jonathan M.; Rivera Pozo, José; Medicina Interna; Medicina; Facultad de Medicina
Aims: Flavonoids may affect platelet function by several mechanisms, including antagonism of TxA2 receptors (TP). These TP are present in many tissues and modulate different signalling cascades. We explored whether flavonoids affect platelet TP signalling, and if they bind to TP expressed in other cell types. Methods: Platelets were treated with flavonoids, or other selected inhibitors, and then stimulated with U46619. Similar assays were performed in aspirinized platelets activated with thrombin. Effects on calcium release were analysed by fluorometry and changes in whole protein tyrosine phosphorylation and activation of ERK 1/2 by Western blot analysis. The binding of flavonoids to TP in platelets, human myometrium and TPaand TPb-transfected HEK 293T cells was explored using binding assays and the TP antagonist 3H-SQ29548. Results: Apigenin, genistein, luteolin and quercetin impaired U46619-induced calcium mobilization in a concentration-dependent manner (IC50 10–30 mm). These flavonoids caused a significant impairment of U46619-induced platelet tyrosine phosphorylation and of ERK 1/2 activation. By contrast, in aspirin-treated platelets all these flavonoids, except quercetin, displayed minor effects on thrombin-induced calcium mobilization, ERK 1/2 and total tyrosine phosphorylation. Finally, apigenin, genistein and luteolin inhibited by >50% 3H-SQ29548 binding to different cell types. Conclusions: These data further suggest that flavonoids may inhibit platelet function by binding to TP and by subsequent abrogation of downstream signalling. Binding of these compounds to TP occurs in human myometrium and in TP-transfected HEK 293T cells and suggests that antagonism of TP might mediate the effects of flavonoids in different tissues.
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Differential effects of quercetin, apigenin and genistein on signalling pathways of protease-activated receptors PAR(1) and PAR(4) in platelets
(Wiley, British Pharmacological Society, 2009-10-28) Guerrero López, José Antonio; Navarro-Núñez, I.; Rivera Pozo, José; Martínez, C.; Vicente García, Vicente; Lozano Almela, María Luisa; Medicina Interna
Background and purpose: The modulation by flavonoids of platelet responses induced by thrombin has been little investigated, and the antiplatelet activity, as well as possible inhibitory mechanisms of these compounds on thrombin signalling, has not yet been elucidated. We explored whether flavonoids affect platelet signalling pathways triggered by thrombin and by the selective activation of its protease-activated receptors (PARs) 1 and 4, and analysed the antagonism of these polyphenols at thrombin receptors. Experimental approach: We investigated the effect of a range of polyphenolic compounds on platelet aggregation, 5-HT secretion, intracellular calcium mobilization, protein kinase activity and tyrosine phosphorylation, triggered by thrombin and PAR agonist peptides (PAR-APs). The ability of these flavonoids to bind to thrombin receptors was investigated by competitive radioligand binding assays using 125I-thrombin. Key results: Quercetin, apigenin and genistein impaired platelet aggregation, as well as 5-HT release and calcium mobilization, induced by thrombin and PAR-APs. Quercetin and apigenin were inhibitors of protein kinases, but genistein exhibited a minimal ability to suppress platelet phosphorylation. Binding assays did not establish any kind of interaction between thrombin receptors and any of the flavonoids tested. Conclusions and implications: Quercetin, apigenin and genistein did not inhibit thrombin responses by interacting with thrombin receptors, but by interfering with intracellular signalling. While inhibition by genistein may be a consequence of affecting calcium mobilization, subsequent platelet secretion and aggregation, for quercetin and apigenin, inhibition of kinase activation may also be involved in the impairment of platelet responses.
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Evaluation of refrigerated platelet concentrates supplemented with low doses of second messenger effectors
(Wiley, 2004-07-27) Pérez Ceballos, Elena; Rivera Pozo, José; Lozano Almela, María Luisa; Candela, M.J.; Corral de la Calle, Javier; Guerrero López, José Antonio; Vicente García, Vicente; Medicina Interna
With the goal of producing haemostatically effective platelet concentrates (PCs) with a longer shelf-life, we aimed to identify a simple combination of platelet inhibitors, with a low pharmacological load, which could avoid the unacceptable loss of platelets stored under refrigerated conditions. PCs stored with different combinations of second messenger effectors were analysed at days 5, 10 and 15 of storage and compared with those supplemented with ThromboSol – a combination of six platelet inhibitors that protects cells from cold damage. The following parameters were analysed: platelet counts, biochemical parameters (glucose, pH, bicarbonate, lactate), cell lysis (lactic dehydrogenase, LDH), membrane glycoproteins (GPs), platelet aggregation, fibrinogen binding and hypotonic shock response. We characterized the combination of amiloride and sodium nitroprusside (at 1/2 the dose included in ThromboSol). This was found to be similar to ThromboSol and superior to nontreated units in the prevention of cold-induced platelet aggregation at day 15 of storage (maintenance of 78% and 80% of initial platelet counts, respectively), preservation of GPIba (11% and 12% better maintenance of mean fluorescence intensity compared with control units, respectively), and reduced cell lysis (13% and 11% decrease in supernatant LDH, respectively). The reduced pharmacological load with the identified solution compared with ThromboSol is an argument in favour of the potential use of these agents when designing strategies to improve PC storage.