Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Background: Resistance to activated protein C(APC) is the most prevalent identifiable risk factor for inherited thrombophilia. Over 90% of APC resistance results from a single point mutation in the Factor V gene. The mutation, termed FV R506Q of FV Leiden, predicts an abnormal Factor Va protein in which arginine, at amino acid position 506, is replaced by glutamine, rendering Factor Va resistant to proteolytic inactivation by APC, thus establishing a life long hypercoagulable state. The current study compared three different polymerase chain reaction (PCR)-based approaches for the detection of FV R506Q. Methods and Results: Sixty-seven patient blood samples were genotyped by (1) analyzing for loss of a Mnl I recognition site, an acquired restriction-fragment-length polymorphism (RFLP) due to FV R506Q; (2) primer-engineered RFLP wherein the presence of FV R506Q results in generation of a novel Nla III recognition site; and (3) allele-specific PCR. Sixty-five of 67 patient samples yielded concordant genotype results by all three PCR methods. Of the remaining 2 of the 67 patients, a "nondiagnostic" result was obtained for either allele-specific PCR or primer-engineered RFLP. Conclusions: A comparative analysis of 67 patient samples demonstrated that primer engineered RFLP and allele-specific PCR offer feasible alternative or confirmatory testing approaches to Mnl I RFLP for the detection of FV R506Q. A high degree of diagnostic concordance was observed for all three methods, and no false positive or negative results were observed with the Mnl I RFLP technique.
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PMID:Resistance to Activated Protein C: Comparison of Three Different PCR Methods for Detection FV R506Q. 1046 76

Recent studies in Caucasian populations have shown an association of the Leiden mutation in factor V with preeclampsia (PE). It consists of a substitution of a G (G1691) with an A (A1691) at nucleotide position 1691 in exon 10, resulting in arginine instead of glutamine at residue 506 at the factor V cleavage site for activated protein C (APC); it contributes to the resistance to APC. The purpose of this study was to determine whether the Leiden mutation is associated with pregnancy-induced hypertension (PIH), including PE, in Japanese women. We examined the genotypes of factor V of 71 Japanese patients with PIH and 109 controls. None of the 180 Japanese women carried the factor V Leiden mutation. To date, the factor V Leiden mutation is rare and not a common cause of PIH in Japan. The results may suggest that there is a significant ethnic difference in the role of the Leiden mutation in compounding the risk factors in the pathogenesis of PIH between Japanese and Caucasian populations.
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PMID:The factor V Leiden mutation is not a common cause of pregnancy-induced hypertension in Japan. 1062 7

Synergistic carbon catabolite repression of the Bacillus subtilis aconitase (citB) gene by glucose and a source of 2-ketoglutarate is dependent on DNA sequences located upstream of the gene. Mutations in a dyad symmetry element centered at position -66 and in a repeat of the downstream arm of the dyad symmetry at position -27 cause derepressed citB expression. In this work, a protein able to bind to a DNA fragment containing these elements was purified and identified. This protein, named CcpC (Catabolite control protein C), shares sequence similarity with members of the LysR family of transcriptional regulators. In addition to binding to the citB promoter, CcpC bound to the promoter of the citZ gene, which encodes the cell's major citrate synthase and is subject to carbon catabolite repression. In a ccpC null mutant, expression of both citB and citZ was derepressed in glucose-glutamine minimal medium, indicating that CcpC is a negative regulator of citB and citZ gene expression. DNase I footprinting experiments showed that CcpC binds to two sites within the citB promoter region, corresponding to the dyad symmetry and -27 elements. In the presence of citrate, a putative inducer, only the dyad symmetry element was fully protected by CcpC. When the dyad symmetry element was mutated, CcpC was no longer able to bind to either the dyad symmetry or -27 elements. Repression of citB and citZ gene expression during anaerobiosis also proved to be mediated by CcpC.
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PMID:CcpC, a novel regulator of the LysR family required for glucose repression of the citB gene in Bacillus subtilis. 1065 96

An increasing number of reports have focused on activated protein C resistance (APCR) as it has been shown not only to be the most common genetic factor predisposing patients to thromboembolic disease but the most common identifiable cause overall. More than 90 percent of the cases of APCR are caused by the factor V Leiden mutation, in which a guanine to adenine substitution in the factor V gene at nucleotide position 1691 results in a glutamine to arginine switch at position 506. Recent studies have also pointed to evidence of an association between APCR/factor V Leiden mutation and hypertensive disorders of pregnancy, first and second trimester miscarriage, placental infarction, and placental abruption.
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PMID:Obstetric implications of activated protein C resistance and factor V Leiden mutation. 1067 55

The endothelial cell protein C receptor (EPCR) is an endothelial cell-specific transmembrane protein that binds both protein C and activated protein C (APC). EPCR regulates the protein C anticoagulant pathway by binding protein C and augmenting protein C activation by the thrombin-thrombomodulin complex. EPCR is homologous to the MHC class 1/CD1 family, members of which contain two alpha-helices that sit upon an 8-stranded beta-sheet platform. In this study, we identified 10 residues that, when mutated to alanine, result in the loss of protein C/APC binding (Arg-81, Leu-82, Val-83, Glu-86, Arg-87, Phe-146, Tyr-154, Thr-157, Arg-158, and Glu-160). Glutamine substitutions at the four N-linked carbohydrate attachment sites of EPCR have little affect on APC binding, suggesting that the carbohydrate moieties of EPCR are not critical for ligand recognition. We then mapped the epitopes for four anti-human EPCR monoclonal antibodies (mAbs), two of which block EPCR/Fl-APC (APC labeled at the active site with fluorescein) interactions, whereas two do not. These epitopes were localized by generating human-mouse EPCR chimeric proteins, since the mAbs under investigation do not recognize mouse EPCR. We found that 5 of the 10 candidate residues for protein C/APC binding (Arg-81, Leu-82, Val-83, Glu-86, Arg-87) colocalize with the epitope for one of the blocking mAbs. Three-dimensional molecular modeling of EPCR indicates that the 10 protein C/APC binding candidate residues are clustered at the distal end of the two alpha-helical segments. Protein C activation studies on 293 cells that coexpress EPCR variants and thrombomodulin demonstrate that protein C binding to EPCR is necessary for the EPCR-dependent enhancement in protein activation by the thrombin-thrombomodulin complex. These studies indicate that EPCR has exploited the MHC class 1 fold for an alternative and possibly novel mode of ligand recognition. These studies are also the first to identify the protein C/APC binding region of EPCR and may provide useful information about molecular defects in EPCR that could contribute to cardiovascular disease susceptibility.
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PMID:Identification of the protein C/activated protein C binding sites on the endothelial cell protein C receptor. Implications for a novel mode of ligand recognition by a major histocompatibility complex class 1-type receptor. 1109 6

Venous thromboembolic disease is an important clinical entity, in which both acquired and genetic risk factors play a causative role. Genetic factors which increase thrombotic risk consist of rare heterogeneous loss-of-function mutations in coagulation-inhibitory factors, such as antithrombin, protein S and C, and more common, but unique, gain-of-function mutations in coagulation factors V and II, so-called factor V-Leiden and prothrombin 20210A. The genetic defect underlying factor V-Leiden is a guanine (G) to adenine (A) mutation in the factor V gene, causing substitution of arginine at position 506 by glutamine, thereby providing resistance to proteolytic cleavage by activated protein C (APC). In the prothrombin 20210A allele a G to A mutation at nucleotide 20210 in the 3'-untranslated region of the prothrombin gene is associated with increased prothrombin levels. The APC-resistance assay is used to screen for the presence of factor V-Leiden. Both factor V-Leiden and prothrombin 20210A are diagnosed by DNA analysis.
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PMID:[From gene to disease; risk factors for venous thrombosis: factor V Leiden and prothrombin 20210A]. 1159 87

masterblind (mbl) is a zebrafish mutation characterised by the absence or reduction in size of the telencephalon, optic vesicles and olfactory placodes. We show that inhibition of Gsk3beta in zebrafish embryos either by overexpression of dominant negative dn gsk3beta mRNA or by lithium treatment after the midblastula transition phenocopies mbl. The loss of anterior neural tissue in mbl and lithium-treated embryos is preceded by posteriorization of presumptive anterior neuroectoderm during gastrulation, which is evident from the anterior shift of marker genes Otx2 and Wnt1. Heterozygous mbl embryos showed increased sensitivity to inhibition of GSK3beta by lithium or dn Xgsk3beta that led to the loss of eyes. Overexpression of gsk3beta mRNA rescued eyes and the wild-type fgf8 expression of homozygous mbl embryos. emx1 that delineates the telencephalon is expanded and shifted ventroanteriorly in mbl embryos. In contrast to fgf8, the emx1 expression domain was not restored upon overexpression of gsk3beta mRNA. These experiments place mbl as an antagonist of the Wnt pathway in parallel or upstream of the complex consisting of Axin, APC and Gsk3beta that binds and phosphorylates beta-catenin, thereby destabilising it. mbl maps on LG 3 close to a candidate gene axin1. In mbl we detected a point mutation in the conserved minimal Gsk3beta-binding domain of axin1 leading to a leucine to glutamine substitution at position 399. Overexpression of wild-type axin1 mRNA rescued mbl completely, demonstrating that mutant axin1 is responsible for the mutant phenotype. Overexpression of mutant L399Q axin1 in wild-type embryos resulted in a dose-dependent dominant negative activity as demonstrated by the loss of telencephalon and eyes. We suggest that the function of Axin1/Mbl protein is to antagonise the Wnt signal and in doing so to establish and maintain the most anterior CNS. Our findings provide new insights into the mechanisms by which the Wnt pathway generates anteroposterior polarity of the neural plate.
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PMID:Ectopic Wnt signal determines the eyeless phenotype of zebrafish masterblind mutant. 1164 Dec 13

The discovery of the resistance to activated protein C (APCR) has provoked a new insight into the etiopathogenesis of venous and arterial thrombosis. APCR is determined in 95% genetically by point mutation in the gene for factor V resulting in substitution of arginine in the position 506 by glutamine. This change makes the activated form of factor V (factor Va) resistant to the cleavage by protein C in the place, where the cleavage takes place most quickly under normal conditions. The mutant factor V is known as factor V Leiden. Factor V Leiden preserves its procoagulation activity for a longer period, resulting thus into thrombophilia with all its negative consequences. The inherited deficiencies of antithrombin III, protein C and protein S occur in 10% of patients suffering from venous thrombosis, whereas factor V Leiden is present in as many as 20 to 60%. Thus, it seems that factor V Leiden is the most important inherited risk factor of venous thrombosis. The results of several trials did not indicate the participation of APCR in the development of myocardial infarction. On the other hand, APCR seems to be a risk factor of cerebrovascular accidents, especially of stroke and transitory brain ischemia. Factor V Leiden is an important risk factor of abortions, especially those occurring in the second trimester of pregnancy. According to recent results, factor V Leiden is considered to play a role in the pathogenesis of venous and arterial thromboses in children. The significant risk potential of factor V Leiden with respect to venous thrombosis development and relatively simple diagnosis of this mutation predispose the investigation of this disorder to become the screening method in indicated groups of patients. The investigation of APCR is recommended in all patients with either first or reoccurring attacks of venous thrombosis or thromboembolism, in patients with positive family history of thrombosis and thromboembolism and in women with repeated abortions, particularly in the second trimester of pregnancy. The investigation of APCR in selected groups of patients and early prophylactic anticoagulation therapy may be important in thrombosis prevention in situations with an increased thrombotic potential. (Tab. 1, Ref. 78.)
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PMID:Resistance to activated protein C--frequent etiologic factor for venous thrombosis. 1172 76

Activated protein C (APC) exerts its anticoagulant activity via proteolytic degradation of the heavy chains of activated factor VIII (FVIIIa) and activated factor V (FVa). So far, three APC cleavage sites have been identified in the heavy chain of FVa: Arg-306, Arg-506, and Arg-679. To obtain more insight in the structural and functional implications of each individual cleavage, recombinant factor V (rFV) mutants were constructed in which two or three of the APC cleavage sites were mutated. After expression in COS-1 cells, rFV mutants were purified, activated with thrombin, and inactivated by APC. During this study we observed that activated rFV-GQA (rFVa-GQA), in which the arginines at positions 306, 506, and 679 were replaced by glycine, glutamine, and alanine, respectively, was still inactivated by APC. Further analysis showed that the inactivation of rFVa-GQA by APC was phospholipid-dependent and sensitive to an inhibitory monoclonal antibody against protein C. Inactivation proceeded via a rapid phase (kx1=5.4 x 10(4) M(-1) s(-1)) and a slow phase (kx2=3.2 x 10(3) M(-1) s(-1)). Analysis of the inactivation curves showed that the rapid phase yielded a reaction intermediate that retained approximately 80% of the original FVa activity, whereas the slow cleavage resulted in formation of a completely inactive reaction product. Inactivation of rFVa-GQA was accelerated by protein S, most likely via stimulation of the slow phase. Immunoblot analysis using a monoclonal antibody recognizing an epitope between Arg-306 and Arg-506 indicated that during the rapid phase of inactivation a fragment of 80 kDa was generated that resulted from cleavage at a residue very close to Arg-506. The slow phase was associated with the formation of fragments resulting from cleavage at a residue 1.5-2 kDa carboxyl-terminal to Arg-306. Our observations may explain the unexpectedly mild APC resistance associated with mutations at Arg-306 (FV HongKong and FV Cambridge) in the heavy chain of FV.
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PMID:Factor Va is inactivated by activated protein C in the absence of cleavage sites at Arg-306, Arg-506, and Arg-679. 1466 Jun 67

In Bacillus subtilis, the catabolite control protein C (CcpC) plays a critical role in regulating the genes encoding the enzymes of the tricarboxylic acid branch of the Krebs citric acid cycle. A gene encoding a potential CcpC homolog and two potential target genes were identified in the Listeria monocytogenes genome. In vitro gel mobility shift assays and DNase I footprinting experiments showed that L. monocytogenes CcpC (CcpC(Lm)) interacts with the promoter regions of citB(Lm) (the gene that is likely to encode aconitase) and lmo0847 (encoding a possible glutamine transporter) and that citrate is a specific inhibitor of this interaction. To study in vivo promoter activity, a new lacZ reporter system was developed. This system allows stable integration into the chromosome of a promoter region transcriptionally fused to a promoterless lacZ gene at a nonessential, ectopic locus. Analysis of strains carrying a citB(Lm)-lacZ or lmo0847-lacZ fusion revealed that CcpC(Lm) represses citB(Lm) and lmo0847 in media containing an excess of glucose and glutamine. In addition, regulation of citB(Lm) expression in rich medium was growth phase dependent; during exponential growth phase, expression was very low even in the absence of CcpC(Lm), but a higher level of citB(Lm) expression was induced in stationary phase, suggesting the involvement of another, as yet unidentified regulatory factor.
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PMID:CcpC-dependent regulation of citB and lmo0847 in Listeria monocytogenes. 1635 34


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