Receptors for extracellular nucleotides are the focus of increasing attention for their ability to cause release of plasma membrane vesicles (microparticles, MPs). Here, we show that monocyte-derived human dendritic cells (DCs) stimulated with a P2X 7 receptor (P2X 7 R) agonist undergo a large release of MPs endowed with procoagulant activity. Functional and Western blot studies revealed that MPs contain the membrane-bound form of tissue factor (TF), a glycoprotein acting as essential cofactor of activated factor VII and triggering blood coagulation. Quiescent DCs express the membrane-bound (full length), as well as truncated alternatively spliced TF forms. DC reactivity to anti-TF Abs disappeared almost completely on stimulation with ATP or benzoyl ATP (BzATP), as shown by immunoblot and confocal microscopy analysis. Concurrently, TF reactivity and activity appeared in the vesicular fraction, indicating that MPs are important carriers for the dissemination of full-length TF form. Activity of MP-bound TF, comparable to that of relipidated recombinant TF, was dose dependently inhibited by the addition of a specific anti-human TF antibody. We infer that a large fraction of this protein, and its procoagulant potential, are "deliverable" after physiological or pathological stimuli. These findings might have implications for triggering and propagating coagulation in healthy and atherosclerotic vessels.-. Stimulation of P2 (P2X 7 ) receptors in human dendritic cells induces the release of tissue factor-bearing microparticles. FASEB J. 21, 1926 -1933 (2007)

The mechanisms underlying the circadian control of gene expression in peripheral tissues and influencing many biological pathways are poorly defined. Factor VII (FVII), the protease triggering blood coagulation, represents a valuable model to address this issue in liver since its plasma levels oscillate in a circadian manner and its promoter contains E-boxes, which are putative DNA-binding sites for CLOCK-BMAL1 and NPAS2-BMAL1 heterodimers and hallmarks of circadian regulation. The peaks of FVII mRNA levels in livers of wild-type mice preceded those in plasma, indicating a transcriptional regulation, and were abolished in Clock ؊/؊ ; Npas2 ؊/؊ mice, thus demonstrating a role for CLOCK and NPAS2 circadian transcription factors. The investigation of Npas2؊/؊ and Clock ⌬19/⌬19 mice, which express functionally defective heterodimers, revealed robust rhythms of FVII expression in both animal models, suggesting a redundant role for NPAS2 and CLOCK. The molecular bases of these observations were established through reporter gene assays. FVII transactivation activities of the NPAS2-BMAL1 and CLOCK-BMAL1 heterodimers were (i) comparable (a fourfold increase), (ii) dampened by the negative circadian regulators PER2 and CRY1, and (iii) abolished upon E-box mutagenesis. Our data provide the first evidence in peripheral oscillators for an overlapping role of CLOCK and NPAS2 in the regulation of circadianly controlled genes.Circadian clocks are endogenous oscillators that drive biochemical, physiological, and behavioral processes in organisms (36), and the alteration of which is associated with human diseases (17,26,42). It is well documented that the circadian rhythms of mammals are controlled by a master circadian pacemaker located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus (38) as well as by peripheral oscillators located in most tissues (43).The basic circadian molecular clockworks consist of interacting positive and negative transcriptional/translational feedback loops (11). The positive loop involves CLOCK-BMAL1 and NPAS2-BMAL1 heterodimers, three basic helix-loop-helix transcriptional activators that bind to E-box elements (CA CGTG) located in the regulatory regions of the Period (Per1, Per2, and Per3) and Cryptochrome (Cry1 and Cry2) genes (3, 13, 16, 24). CRY and PER proteins form oligomers that, once transported into the nucleus, repress their own transcription by inhibiting CLOCK-BMAL1 or NPAS2-BMAL1 (25). Furthermore, other transcription factors (CIPC, DEC1, DEC2, and Fbxl3) play important roles in the negative-feedback loop (15,19,44). The positive and negative limbs are interlaced: CLOCK-BMAL1 heterodimers indirectly regulate a rhythm in Bmal1 transcription; the nuclear orphan receptor genes Reverb␣ and Rora are coordinately activated by CLOCK-BMAL1 to produce proteins that compete for the same promoter element but have opposing actions on Bmal1 transcription (1, 32). Oscillations in gene expression resulting from this feedback loop have period lengths of approximately 24 h, thus giving ri...

Summary. Background: Combined vitamin K-dependent clotting factor (VKCF) deficiency type 2 (VKCFD2) is a rare bleeding disorder caused by mutated vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) gene. Methods and results: An Italian patient with moderate to severe bleeding tendency was genotyped, and found to be homozygous for the unique VKORC1 mutation (Arg98Trp) so far detected in VKCFD2. The activity levels of VKCFs were differentially reduced, and inversely related to the previously estimated affinity of procoagulant factor propeptides for the c-carboxylase. The normal (factor IX) or reduced antigen levels (other VKCFs) produced a gradient in specific activities. Vitamin K supplementations resulted in reproducible, fast and sustained normalization of PT and APTT. At 24 h the activity/antigen ratios of VKCFs were close to normal, and activity levels were completely (factor VII and IX), virtually (prothrombin, factor X and protein C) or partially (protein S) restored. Thrombin generation assays showed a markedly shortened lag time. The time to peak observed at low tissue factor concentration, potentially mimicking the physiological trigger and able to highlight the effect of reduced protein S levels, was shorter than that in pooled normal plasma. At 72 h the thrombin generation times were normal, and the decrease in activity of procoagulant VKCFs was inversely related to their half-life in plasma. The improved coagulation phenotype permitted the uneventful clinical course after invasive diagnostic procedures. Conclusions: Modification of coagulation phenotypes in VKCFD2 after vitamin K supplementation was clinically beneficial, and provided valuable patterns of factor specific biosynthesis, half-life and decay.

KEY WORDS: nonsense mutations; ribosome; readthrough; coagulation factor; F9The mechanism through which nonsense mutations impair gene expression and cause human genetic disease [Mort et al., 2008] consists of premature translation termination, and the synthesis of truncated proteins with loss-of-function features. Moreover, these mutations can trigger nonsense-mediated decay of mRNA (NMD) † First two authors have contributed equally to the work.

BackgroundRelative little attention has been devoted until now to the combined effects of gene polymorphisms of the hemostatic pathway as risk factors for Myocardial Infarction (MI), the main thrombotic complication of Coronary Artery Disease (CAD). The aim of this study was to evaluate the combined effect of ten common prothrombotic polymorphisms as a determinant of MI.Methodology/Principal FindingsWe studied a total of 804 subjects, 489 of whom with angiographically proven severe CAD, with or without MI (n = 307; n = 182; respectively). An additive model considering ten common polymorphisms [Prothrombin 20210G>A, PAI-1 4G/5G, Fibrinogen β -455G>A, FV Leiden and “R2”, FVII -402G>A and -323 del/ins, Platelet ADP Receptor P2Y12 -744T>C, Platelet Glycoproteins Ia (873G>A), and IIIa (1565T>C)] was tested. The prevalence of MI increased linearly with an increasing number of unfavorable alleles (χ2 for trend = 10.68; P = 0.001). In a multiple logistic regression model, the number of unfavorable alleles remained significantly associated with MI after adjustment for classical risk factors. As compared to subjects with 3-7 alleles, those with few (≤2) alleles had a decreased MI risk (OR 0.34, 95%CIs 0.13–0.93), while those with more (≥8) alleles had an increased MI risk (OR 2.49, 95%CIs 1.03–6.01). The number of procoagulant alleles correlated directly (r = 0.49, P = 0.006) with endogenous thrombin potential.ConclusionsThe combination of prothrombotic polymorphisms may help to predict MI in patients with advanced CAD.

Combined deficiency of the vitamin K-dependent clotting factors (VKCFD) is a rare bleeding disorder involving defective gamma-carboxylation of coagulation factors II , VII, IX and X as well as natural anticoagulants protein C and protein S. The disease is characterized by a cluster of different, often life threatening, bleeding symptoms occurring both spontaneously and in a surgical setting. In the present paper we describe two different treatment modalities to be used both in a programmed surgical procedure and in an emergency scenario. As this disease is a natural model that resembles oral anticoagulation, our experience discloses a possible rationale in the use of recombinant activated FVII for warfarin reversal.

RIV did not significantly interfere with the prothrombinase-based assay used for the assessment of APCr, and this was observed to occur independently of FV status. However, only concentrations up to 400 ng/mL were tested and, therefore, what occurs in the presence of higher doses remains to be investigated.

To cite this article: Passaro A, Calzavarini S, Volpato S, Caruso P, Poli A, Fellin R, Bernardi F. Reduced factor VII and factor VIII levels and prolonged thrombin-generation times during a healthy diet in middle-aged women with mild to moderate cardiovascular disease risk. J Thromb Haemost 2008; 6: 2088-94. Summary. Background:No experimental study has investigated the effect of whole-diet therapies on a wide range of hemostatic parameters, and their relationship with metabolic and inflammatory markers. Such information was sought in middle-aged women with moderate cardiovascular disease (CVD) risk subjected to an integrated healthy diet. Methods: Forty-nine premenopausal women were screened for C-reactive protein levels ‡1 mg L )1 and at least one additional CVD risk factor. Sixteen women (age: 43-54 years) were selected and received a 12-week diet (four phases) integrating National Cholesterol Education Program-Adult Treatment Panel-III recommendations with components of a Mediterranean-style diet. Results: We observed a reduction in body mass index (BMI) (P = 0.001), waist circumference (P = 0.005), total (P = 0.011) and low-density lipoprotein (LDL) cholesterol levels (P = 0.035). Antigen levels of coagulation factor (F)VII (P = 0.003) and FVIII (P = 0.005) were clearly reduced by dietary intervention, which also appeared to decrease circulating tissue factor but not fibrinogen and von Willebrand factor (VWF) antigen levels. Levels of FVIII and tumor necrosis factor-a, among the inflammation markers, showed the highest correlation, particularly before the intervention (r = 0.55, P = 0.032). Only this cytokine influenced FVIII variation over time, thus highlighting new relations between coagulation and cellular components of inflammation. The functional effect of diet on coagulation was indicated by markedly prolonged thrombin generation initiation and propagation times (lag time, P = 0.002; time to peak, P = 0.005). Conclusions: The changes observed in coagulation initiation and amplification phases, body composition and lipid profile could translate into a remarkable decrease in the risk for cardiovascular disease.Our observations suggest novel relationships between coagulation and inflammatory components.