RESUMEN
Coagulation factor XIII (FXIII) is a protransglutaminase involved in the last step of the coagulation cascade by stabilising the fibrin clot. Recently, a common variation (FXIII Val34Leu) has been associated with a decreased risk of myocardial infarction and deep venous thrombosis. Val34Leu is critically located near the thrombin activation site of FXIII-A. In this study we investigated its effects on the activation of FXIII. Both recombinant and platelet-derived FXIII Val34Leu variants were shown to be more susceptible to thrombin cleavage than the wild type FXIII. The rate of enzymatic activation of FXIII Val34Leu was found increased, however, the specific activity of fully activated wild type FXIII and the Val34Leu mutant did not differ. During the course of thrombin-induced activation of FXIII fibrin gamma-chain dimerisation and alpha-chain polymerisation developed more rapidly with the Val34Leu mutant. The increased rate of fibrin stabilisation brought about by the Val34Leu FXIII seems to be paradoxically associated with a protective effect against pathological thrombosis.
Asunto(s)
Polimorfismo Genético , Transglutaminasas/genética , Animales , Coagulación Sanguínea , Trastornos de la Coagulación Sanguínea/etiología , Trastornos de la Coagulación Sanguínea/genética , Células COS , Humanos , Mutación , Factores de Riesgo , Transglutaminasas/metabolismoRESUMEN
Val34Leu polymorphism of the A subunit of coagulation factor XIII (FXIII-A) is located in the activation peptide (AP) just 3 amino acids away from the thrombin cleavage site. This mutation has been associated with a protective effect against occlusive arterial diseases and venous thrombosis; however, its biochemical consequences have not been explored. In the current study it was demonstrated that the intracellular stability and the plasma concentration of FXIII of different Val34Leu genotypes are identical, which suggests that there is no difference in the rate of synthesis and externalization of wild-type and mutant FXIII-A. In contrast, the release of AP by thrombin from the Leu34 allele proceeded significantly faster than from its wild-type Val34 counterpart. By molecular modeling larger interaction energy was calculated between the Leu34 variant and the respective domains of thrombin than between the Val34 variant and thrombin. In agreement with these findings, the activation of mutant plasma FXIII by thrombin was faster and required less thrombin than that of the wild-type variant. Full thrombin activation of purified plasma FXIII of different genotypes, however, resulted in identical specific transglutaminase activities. Similarly, the mean specific FXIII activity in the plasma was the same in the groups with wild-type, heterozygous, and homozygous variants. Faster activation of the Leu34 allele hardly could be associated with its presumed protective effect against venous thrombosis. No such protective effect was observed in a large group of patients with familial thrombophilia.
Asunto(s)
Factor XIII/genética , Leucina , Polimorfismo Genético , Trombofilia/epidemiología , Trombofilia/genética , Valina , Adulto , Secuencia de Aminoácidos , Sitios de Unión , Cromatografía Líquida de Alta Presión , Factor XIII/química , Factor XIII/metabolismo , Femenino , Expresión Génica , Genotipo , Humanos , Masculino , Modelos Moleculares , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Proteínas Recombinantes , Trombina/metabolismo , Trombina/farmacología , Transglutaminasas/metabolismoRESUMEN
High plasminogen activator inhibitor-1 (PAI-1) plasma levels increase future risk of myocardial infarction (MI). The 4G allele of the 4G/5G polymorphism of the PAI-1 gene has been associated with increased plasma levels of PAI-1. The association of the PAI-1 polymorphism with coronary narrowings, coronary thrombosis and myocardial infarction (MI) was studied in a prospective autopsy series of 300 middle-aged Caucasian Finnish men (33 to 69 yrs) suffering sudden out-of-hospital death (Helsinki Sudden Death Study). The 4G allele was found in 76.8% of men with sudden cardiac death (SCD) compared to 67.5% in men who died accidentally and 63.2% in men who died of other diseases (p = 0.08 and p = 0.055, respectively). Men possessing the 4G allele had more often acute MI (OR 3.5; p <0.05) and coronary thrombosis (OR 5.5. p = 0.01) compared to 5G homozygotes. 5G homozygotes, comprising one third of the men in our study, seem to be at a decreased risk of thrombosis, whereas carriers of the common 4G allele have an increased risk of thrombosis, AMI and possibly SCD compared to 5G homozygotes.
Asunto(s)
Trombosis Coronaria/mortalidad , Muerte Súbita/epidemiología , Infarto del Miocardio/mortalidad , Inhibidor 1 de Activador Plasminogénico/genética , Polimorfismo Genético , Accidentes/mortalidad , Alelos , Autopsia , Causas de Muerte , Comorbilidad , Enfermedad Coronaria/complicaciones , Enfermedad Coronaria/patología , Trombosis Coronaria/genética , Vasos Coronarios/patología , Muerte Súbita Cardíaca/epidemiología , Finlandia/epidemiología , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Infarto del Miocardio/genética , Estudios Prospectivos , Riesgo , Fumar/epidemiología , Suicidio/estadística & datos numéricosRESUMEN
BACKGROUND: Earlier studies have indicated that inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is associated with thromboembolic complications, whereas inherited disorders of coagulation occur less often than expected in IBD patients. The point mutation Arg506Gln of factor V (Factor V Leiden), resulting in resistance to activated protein C, is the commonest inherited form of thrombophilia. Alterations in circulating levels of factor XIII (FXIII) have been reported among IBD patients. We investigated whether Factor V Leiden or inherited Val34Leu polymorphism of FXIII would associate with IBD or its clinical outcome. METHODS: Factor V Leiden mutation and FXIII Val34Leu polymorphism were assayed in 328 unrelated Finnish patients with UC and 235 patients with CD by solid-phase minisequencing techniques. The control groups comprised 142 apparently healthy Finnish subjects and 120 Finnish blood donors. RESULTS: The frequency of Factor V Leiden mutation among IBD patients (4.5%) was not significantly different from that in subjects living in the same area (2.1%). No significant differences could be observed in the FXIII Val34Leu polymorphism allele frequencies between patients and controls. Clinical features of IBD, including the disease extent, requirement for immunosuppressive drugs, and occurrence of complications, seemed to be independent of these two clotting factor variants analyzed. CONCLUSIONS: Our data do not support an aetiologic or disease-modifying role for the factor V mutation or factor XIII Val34Leu polymorphism in IBD.
Asunto(s)
Factor V/genética , Factor XIII/genética , Enfermedades Inflamatorias del Intestino/genética , Mutación Puntual , Polimorfismo Genético , Adulto , Femenino , Finlandia/epidemiología , Humanos , Enfermedades Inflamatorias del Intestino/epidemiología , Masculino , Persona de Mediana EdadRESUMEN
Factor XIII is a transglutaminase that crosslinks fibrin in the last steps of the coagulation process. A few polymorphic sites have been identified in this gene, one of them being a point mutation (FXIII Val34Leu), leading to an amino acid change of valine to leucine. Recently, in British patients, FXIII 34Leu allele was suggested to be associated with a decreased incidence of myocardial infarction (MI). PAI-1 4G/4G genotype seemed to lessen the beneficial effect of FXIII 34Leu allele. The aim of our study was to further investigate the possible protective role of the FXIII 34Leu allele against MI and its suggested interaction with the PAI-1 4G/5G polymorphism. We carried out genotype analyses for FXIII Val34Leu using solid-phase minisequencing in two independent Finnish study groups. In our study, the FXIII 34Leu allele was associated with a lower risk of MI (P = 0.009), however, the PAI-1 4G allele showed no interaction with this polymorphism. To establish the population frequency of the FXIII 34Leu allele and to study the possible variations in Finland four DNA pools from different geographical areas of Finland were genotyped. No significant differences in the allele frequencies were observed (21-28%) except in the Eastern Kainuu area (13%), an area with an increased risk of mortality from coronary artery disease (CAD), supporting the results presented above. The association of FXIII 34Leu variant with a lower incidence of myocardial infarction suggests a new role for FXIII in a polygenic thrombotic disease.
Asunto(s)
Factor XIII/genética , Fibrinólisis/genética , Infarto del Miocardio/epidemiología , Infarto del Miocardio/genética , Alelos , ADN/análisis , Cartilla de ADN/química , Finlandia/epidemiología , Marcadores Genéticos , Genotipo , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Inhibidor 1 de Activador Plasminogénico/genética , Polimorfismo Genético , Prevalencia , Factores de RiesgoRESUMEN
VEGF-C is a recently characterised endothelial growth factor structurally related to vascular endothelial growth factor (VEGF). We studied the expression of VEGF-C and VEGF in the cells of peripheral blood and in the umbilical cord blood CD 34+ cells, representing haematopoietic progenitor cells. Expression of VEGF-C was detected in the CD34+ cells. In peripheral blood VEGF-C mRNA was restricted to platelets and T-cells. In contrast to the expression pattern of VEGF-C, VEGF mRNA was detected in all peripheral blood cell fractions studied, and also in CD34+ cells. VEGF-C mRNA was also detected in fresh bone marrow samples of acute leukaemia patients, but the expression did not show lineage specificity. VEGF-C and VEGF polypeptides were present in platelets and they were released from activated platelets together with the release of beta-thromboglobulin, suggesting that VEGF-C and VEGF reside in the alpha-granules of platelets. VEGF-C and VEGF, released from activated platelets, may have a role in angiogenesis during wound healing, and possibly also in other pathological conditions, such as atherosclerosis, tumour growth, and metastasis formation.
Asunto(s)
Antígenos CD34/sangre , Plaquetas/metabolismo , Factores de Crecimiento Endotelial/biosíntesis , Células Madre Hematopoyéticas/inmunología , Leucemia/metabolismo , Activación Plaquetaria , Secuencia de Aminoácidos , Estudios de Casos y Controles , Humanos , Leucemia/inmunología , Leucemia/patología , Linfocinas/biosíntesis , Datos de Secuencia Molecular , Factor A de Crecimiento Endotelial Vascular , Factor C de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
We generated a panel of monoclonal antibodies against the extracellular domain of the Tie receptor tyrosine kinase and studied its expression in human haemopoietic and tumour cell lines and in samples from leukaemia patients. Most of the erythroblastic/megakaryoblastic (6/8), 2/7 myeloid and 3/6 B-lymphoblastic leukaemia cell lines were Tie-positive. The erythroblastic/megakaryoblastic leukaemia cell lines also expressed the related Tie-2/Tek gene and, surprisingly, its recently cloned ligand gene angiopoietin-1, which was located in chromosome 8q23.1. In addition, 16% of freshly isolated leukaemia samples were Tie positive. Peripheral blood mononuclear cells were Tie negative, but a few Tie positive cells were found in immunoperoxidase staining of mobilized peripheral blood stem cells. Long-term culture of isolated umbilical cord blood CD34+ Tie+ and CD34+ Tie- cells indicated that the Tie+ fraction contained a slightly higher frequency of cobblestone area forming cells (CAFC). Thus, Tie is expressed on haemopoietic progenitor cells and some leukaemic blasts. The coexpression of Tie-2 and angiopoietin-1 in megakaryoblastic leukaemia cell lines suggests the existence of an autocrine ligand/receptor signalling loop in these cells.