Down-regulation of Factor IXa in the Factor Xase Complex by Protein Z-dependent Protease Inhibitor

Heeb, Mary J.; Cabral, Katia M. S.; Ruan, Lingjuan

doi:10.1074/jbc.m506502200

Cited by 33 publications

(26 citation statements)

References 34 publications

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“…However, unlike the inhibition of factor Xa by ZPI, this inhibition was not enhanced by protein Z, lipid, and calcium ion cofactors but was accelerated ϳ2-fold by heparin (not shown), again confirming the reported behavior of plasma ZPI (7). Similar to the report of Broze and co-workers (6) but contrasting that of Heeb et al (25), we were unable to detect any inhibition of factor IXa by recombinant ZPI either in the absence or presence of protein Z, phospholipid, and calcium.…”

Section: Resultssupporting

confidence: 57%

“…Direct comparison of recombinant and plasma ZPIs verified that the two serpin forms inhibited factor Xa with equivalent rates in the presence of cofactors. Contrasting a recent report (25), we found no evidence that ZPI could inhibit factor IXa in the absence or presence of protein Z and procoagulant membranes. Our finding that ZPI was not cleaved by factor IXa under these conditions suggests that the ZPI reactive loop sequence is not recognized by free or membrane-bound factor IXa, and therefore not likely to be a physiologic target of ZPI, consistent with the initial report of Broze and co-workers (6).…”

Section: Discussioncontrasting

confidence: 57%

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Kinetic Characterization of the Protein Z-dependent Protease Inhibitor Reaction with Blood Coagulation Factor Xa

Huang

Swanson

Broze

et al. 2008

Journal of Biological Chemistry

109

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Protein Z-dependent protease inhibitor (ZPI) is a recently identified member of the serpin superfamily that functions as a cofactor-dependent regulator of blood coagulation factors Xa (FXa) and XIa. Here we show that ZPI and its cofactor, protein Z (PZ), inhibit procoagulant membrane-bound factor Xa by the branched pathway acyl-intermediate trapping mechanism used by other serpins, but with significant variations of this mechanism that are unique to ZPI. Rapid kinetic analyses showed that the reaction proceeded by the initial assembly of a membraneassociated PZ-ZPI-FXa Michaelis complex (K M 53 ؎ 5 nM) followed by conversion to a stable ZPI-FXa complex (k lim 1.2 ؎ 0.1 s ؊1 ). Cofactor premixing experiments together with independent kinetic analyses of ZPI-PZ and factor Xa-PZ-membrane complex formation suggested that assembly of the Michaelis complex through either ZPI-PZ-lipid or factor Xa-PZ-lipid intermediates was rate-limiting. Reaction stoichiometry analyses and native PAGE showed that for every factor Xa molecule inhibited by ZPI, two serpin molecules were cleaved. Native PAGE and immunoblotting showed that PZ dissociated from ZPI once ZPI forms a stable complex with FXa, and kinetic analyses confirmed that PZ acted catalytically to accelerate the membrane-dependent ZPI-factor Xa reaction. The ZPI-FXa complex was only transiently stable and dissociated with a rate constant that showed a bell-shaped pH dependence indicative of participation of factor Xa active-site residues. The complex was detectable by SDS-PAGE when denatured at low pH, consistent with it being a kinetically trapped covalent acyl-intermediate. Together our findings show that ZPI functions like other serpins to regulate the activity of FXa but in a manner uniquely dependent on protein Z, procoagulant membranes, and pH.Activation of factor X is a focal point for regulation of the blood coagulation cascade. Formation of factor Xa through the extrinsic pathway and its amplification through the intrinsic pathway are regulated by the Kunitz inhibitor, tissue factor pathway inhibitor, and by the serpin, antithrombin, and its cofactor, heparin (1, 2). Whereas tissue factor pathway inhibitor regulates the activity of factor Xa bound in a physiologic complex with membrane-bound tissue factor and factor VIIa, antithrombin and heparin poorly inhibit factor Xa bound in procoagulant membrane-associated physiologic complexes and instead appear to target factor Xa that escapes from its membrane sites of action (3, 4). Broze and co-workers (5, 6) have identified another serpin, protein Z-dependent protease inhibitor or ZPI, that specifically inhibits factor Xa bound to procoagulant membranes, suggesting a potential means for dynamic regulation of factor Xa bound in procoagulant complexes such as prothrombinase and factor Xase. ZPI 2 is a member of the serpin superfamily of protein protease inhibitors and is unusual in requiring protein Z, anionic phospholipids, and calcium as cofactors to rapidly inhibit factor Xa (6). Factor XIa is also inhibited by ZPI,...

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Section: Resultssupporting

confidence: 57%

Section: Discussioncontrasting

confidence: 57%

Kinetic Characterization of the Protein Z-dependent Protease Inhibitor Reaction with Blood Coagulation Factor Xa

Huang

Swanson

Broze

et al. 2008

Journal of Biological Chemistry

109

View full text Add to dashboard Cite

show abstract

“…5 A recent paper supports that the ZPI may be an unusual physiologic regulator of both the intrinsic FXase and the prothrombinase complexes. 6 The possible relevance of this system in regulating the coagulation response and in thrombosis arises from the PZ knock-out mice, which indicated that PZ appears to dampen the prothrombotic response. Moreover, the PZ-deficient mice exhibited prothrombotic tendency in combination with factor V Leiden.…”

Section: Introductionmentioning

confidence: 99%

A nonsense polymorphism in the protein Z-dependent protease inhibitor increases the risk for venous thrombosis

Corral

Gónzález-Conejero

Soria

et al. 2006

Blood

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The protein Z-dependent protease inhibitor (ZPI) is a hemostatic serpin with anticoagulant activity. As for antithrombin, deficiency of ZPI could have relevant thrombotic consequences. We have studied 6 genetic modifications affecting the ZPI gene, identifying 5 haplotypes. Haplotype H5 is featured by a stop codon at position 67. The relevance of these genetic modifications and haplotypes in venous thrombosis was evaluated in a case-control study including 1018 patients and 1018 age-and sex-matched controls. Surprisingly, the H5 haplotype was found in 0.9% of controls, supporting that the Arg67Stop change is a low frequency nonsense polymorphism. The prevalence of this haplotype increased significantly in patients (3.0%), one of whom was in a homozygous state. Multivariate analysis confirms that carriers have a 3.3-fold risk of developing venous thrombosis (P ‫؍‬ .002; 95% CI: 1.5-7.1). Moreover, we observed a significant association of this polymorphism with familial history of thrombosis (P < .001). Our study supports that the ZPI Arg67Stop nonsense polymorphism might be an independent genetic risk factor for venous thrombosis. This polymorphism has slightly lower prevalence but similar thrombotic risk than the FV Leiden or prothrombin 20210A. Although further studies are required, all available data support that the ZPI is a candidate to play a significant role in thrombosis and should be evaluated in thrombophilic studies. (Blood. 2006;108:177-183)

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“…PZ, depending on vitamin K, synthesized in liver, is cofactor [12] of protease inhibitors (ZPI) depending on weight 72 kD and PZ-ZPI association FXa and inhibits FXIa, decreases thrombin structure [13,14]. ZPI in plasma, is at very high levels according to PZ and it is connected to PZ with 1:1 proportion.…”

Section: Resultsmentioning

confidence: 99%

The possible relationship between epistaxis and protein Z plasma levels

Turhan¹,

Çalcı²,

Acar³

et al. 2017

Med-Science

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Epistaxis represents a very common emergency in any ear, nose, and throat (ENT) department around the world. Frequently seen in the systemic vascular patients, nasal anatomy the lack of vessels muscular structure, the absence of vasoconstriction ability, the clot formed in the bleeding area further increases the amount of bleeding supports the importance of vascular causes in the etiology. The purpose of our research is to evaluate the relationship between epistaxis and plasma protein Z levels. 18 patients with epistaxis and 30 healthy subjects were investigated. 8 of patients gruop (44.4%) participating the research were women, 10 of them (55.6%) were men, in total 18 people. Control group consisted of 16 women (53.3%), 14 men (46.7%), 30 people in total. Both groups were measured about protein C (PC), protein S (PS), and protein Z (PZ). PC and PS concentrations were determined in plasma by using cholorimetric and the formation clotting methods, respectively. Sandwich enzyme immunoassay method was used for the determination of PZ plasma concentrations. While statistically there were no significant differences detected comparing Protein S and Protein C levels data of control group, (p=0.27 ve p=0.29 respectively). Protein Z levels of patient group was found significantly lower than Protein Z levels of control group and this was found to be statistically significant (p<0.001). Vascular causes are known to take part in the etiology of epistaxis. Defects of Protein Z function and/or secretion, are associated also with bleeding, venous thrombosis and arterial thromboembolism as well as including especially epistaxis.

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Down-regulation of Factor IXa in the Factor Xase Complex by Protein Z-dependent Protease Inhibitor

Cited by 33 publications

References 34 publications

Kinetic Characterization of the Protein Z-dependent Protease Inhibitor Reaction with Blood Coagulation Factor Xa

Kinetic Characterization of the Protein Z-dependent Protease Inhibitor Reaction with Blood Coagulation Factor Xa

A nonsense polymorphism in the protein Z-dependent protease inhibitor increases the risk for venous thrombosis

The possible relationship between epistaxis and protein Z plasma levels

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