Protein C Inhibitor Secreted from Activated Platelets Efficiently Inhibits Activated Protein C on Phosphatidylethanolamine of Platelet Membrane and Microvesicles

Nishioka, Junji; Ma, Ning; Hayashi, Tatsuya; Suzuki, Koji

doi:10.1074/jbc.273.18.11281

Cited by 41 publications

(45 citation statements)

References 59 publications

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“…1C). The larger hydrophobic pocket found in PCI may be necessary to accommodate the longer and more hydrophobic retinoids, or might be utilized for the apparently specific interaction with the phospholipid phosphatidyl ethanolamine (56). One fortuitous finding from the P2 1 crystal form was a hydrophobic crystal contact in the helix A gap, in a position which overlaps with that of thyroxine in complex with TBG (Fig.…”

Section: Discussionmentioning

confidence: 99%

Structure of Native Protein C Inhibitor Provides Insight into Its Multiple Functions

Adams

Kjellberg

et al. 2007

Journal of Biological Chemistry

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Protein C inhibitor (PCI) is a multifunctional serpin with wide ranging protease inhibitory functions, unique cofactor binding activities, and potential non-inhibitory functions akin to the hormone-transporting serpins. To gain insight into the molecular mechanisms utilized by PCI we developed a robust expression system in Escherichia coli and solved the crystal structure of PCI in its native state. The five monomers obtained from our two crystal forms provide an NMR-like ensemble revealing regions of inherent flexibility. The reactive center loop (RCL) of PCI is long and highly flexible with no evidence of hinge region incorporation into ␤-sheet A, as seen for other heparin-binding serpins. We adapted an extrinsic fluorescence method for determining dissociation constants for heparin and find that the N-terminal tail of PCI and residues adjacent to helix H are not involved in heparin binding. The minimal heparin length capable of tight binding to PCI was determined to be chains of eight monosaccharide units. A large hydrophobic pocket occupied by hydrophobic crystal contacts was found in an analogous position to the hormone-binding site in thyroxine-binding globulin. In conclusion, the data presented here provide important insights into the mechanisms by which PCI exercises its multiple inhibitory and non-inhibitory functions.

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Section: Discussionmentioning

confidence: 99%

Structure of Native Protein C Inhibitor Provides Insight into Its Multiple Functions

Adams

Kjellberg

et al. 2007

Journal of Biological Chemistry

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“…The immobilization procedure was the same as described above. Four different concentrations of A. albopictus saliva (15,25,50, and 90 g/ml in HBS-P) were manually injected over the four flow cells in the sensor chip for 90 s at a flow rate of 20 l/min. The complex dissociation was monitored for 500 s, and the sensor surface was regenerated by a pulse of 5 s of 10 mM glycine-HCl, pH 1.5, at 40 l/min.…”

Section: Methodsmentioning

confidence: 99%

“…7A demonstrates that Alboserpin binds to PC and PE but, surprisingly, not to PS. This phospholipid specificity distinguishes Alboserpin and PCI, which is a PS-binding serpin (50). It also binds to a mixture of PC/PS (4:1), which mimics phospholipid composition of activated platelets.…”

Section: Kinetics and Stoichiometry Of Alboserpin-fxa Interactions-mentioning

confidence: 96%

“…Alboserpin Interacts with PC and PE but Not with PSAmong serpin family members, PCI was initially found to bind to PE, PS, and PC (50). However, PCI was later demonstrated to interact with oxidized PE or oxidized PS but not with PC (47,51).…”

Section: Kinetics and Stoichiometry Of Alboserpin-fxa Interactions-mentioning

confidence: 99%

“…Studies have also demonstrated that PE enhances the PS-mediated sensitivity of factor VIIa-tissue factor activity (53) and induces high affinity binding sites for factor VIII on surfaces containing PS (54). Moreover, PE has been reported in tumor cell membranes (55) and is known to regulate the activation of blood coagulation by enhancing APC inhibition by PCI (50,51). It is possible that occupation of these sites by Alboserpin interferes with the inhibitory function of PCI toward APC, which displays particularly important anticoagulant and anti-inflammatory activities in vivo (7,56).…”

Section: Kinetics and Stoichiometry Of Alboserpin-fxa Interactions-mentioning

confidence: 99%

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Alboserpin, a Factor Xa Inhibitor from the Mosquito Vector of Yellow Fever, Binds Heparin and Membrane Phospholipids and Exhibits Antithrombotic Activity

Calvo

Mizurini

Sá-Nunes

et al. 2011

Journal of Biological Chemistry

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The molecular mechanism of factor Xa (FXa) inhibition by Alboserpin, the major salivary gland anticoagulant from the mosquito and yellow fever vector Aedes albopictus, has been characterized. cDNA of Alboserpin predicts a 45-kDa protein that belongs to the serpin family of protease inhibitors. Recombinant Alboserpin displays stoichiometric, competitive, reversible and tight binding to FXa (picomolar range). Binding is highly specific and is not detectable for FX, catalytic siteblocked FXa, thrombin, and 12 other enzymes. Alboserpin displays high affinity binding to heparin (K D ϳ 20 nM), but no change in FXa inhibition was observed in the presence of the cofactor, implying that bridging mechanisms did not take place. Notably, Alboserpin was also found to interact with phosphatidylcholine and phosphatidylethanolamine but not with phosphatidylserine. Further, annexin V (in the absence of Ca 2؉ ) or heparin outcompetes Alboserpin for binding to phospholipid vesicles, suggesting a common binding site. Consistent with its activity, Alboserpin blocks prothrombinase activity and increases both prothrombin time and activated partial thromboplastin time in vitro or ex vivo. Furthermore, Alboserpin prevents thrombus formation provoked by ferric chloride injury of the carotid artery and increases bleeding in a dose-dependent manner. Alboserpin emerges as an atypical serpin that targets FXa and displays unique phospholipid specificity. It conceivably uses heparin and phosphatidylcholine/phosphatidylethanolamine as anchors to increase protein localization and effective concentration at sites of injury, cell activation, or inflammation.

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Regulation of carcinoma cell invasion by protein C inhibitor whose expression is decreased in renal cell carcinoma

Wakita

Hayashi

Nishioka

et al. 2003

Intl Journal of Cancer

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Protein C inhibitor (PCI), a member of the serine protease inhibitor family, is produced in various human tissues, including the liver, kidney and testis. In addition to inhibiting the anticoagulant protein C pathway, PCI also inhibits urinary plasminogen activator (uPA), which is a well-known mediator of tumor cell invasion. In the present study, to clarify the biologic significance of PCI in the kidney, we compared the expression of PCI between human renal cell carcinoma (RCC) tissue and nontumor kidney tissue. The PCI antigen level in RCC tissue was found to be significantly lower than in nontumor kidney tissue, and expression of PCI mRNA was detected in normal renal proximal tubular epithelial cells (RPTEC), but not in RCC or in an RCC cell line (Caki-1 cells). Key words: protein C inhibitor; urinary plasminogen activator; renal cell carcinoma; tumor invasionProtein C inhibitor (PCI) was originally identified as an inhibitor of the anticoagulant protease, activated protein C, 1 and was subsequently found to inhibit other proteases involved in blood coagulation and fibrinolysis, such as thrombin, 2 thrombin-thrombomodulin complex, 3 factor Xa, 2 factor XIa, 4 plasma kallikrein 4 and urinary plasminogen activator (uPA). 5 Human plasma PCI is believed to be produced mainly by the liver, 6 but is also synthesized in the kidneys and the reproductive organs, including the testis, seminal vesicles and ovary. 7,8 Thus, besides its function in the regulation of blood coagulation, PCI may also play a role in the regulation of reproduction. Recently, Uhrin et al. 9 reported that PCI knockout male mice are apparently healthy but infertile, and that this infertility is caused by abnormal spermatogenesis induced by destruction of the Sertoli cell barrier. In the kidneys, PCI is mainly synthesized by proximal tubular epithelial cells, 10 and most urinary PCI is present in complex with uPA, 11 which it inhibits; hence, PCI is also referred to as plasminogen activator inhibitor-3 (PAI-3). However, the physiologic role of uPA inhibition by PCI in the urinary tract is unknown.It is known that metastasis and invasion of various tumor cells are mediated by uPA and its receptor. 12 uPA is inhibited by PAI-1 and PAI-2, 13 the former of which has been reported to be essential for regulation of tumor cell invasion and metastasis by promoting angiogenesis. 14,15 Previously, it was shown that the expression of uPA is lower, that the expression of uPA receptor is moderately higher and that the expression of PAI-1 is significantly higher in human renal cell carcinoma (RCC) than in nontumor kidney tissue. 16,17 Furthermore, Swiercz et al. 18 suggested that the expression of uPA, its receptor and PAI-1 correlate with the aggressive phenotype of RCC. These studies suggest the importance of the plasminogen activator system, including uPA, its receptor and PAI-1, in the process of RCC tumor cell invasion; however, there is no direct evidence yet that uPA regulates the invasiveness of RCC cells. It is also known that uPA and/or plasmin may ...

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Protein C Inhibitor Secreted from Activated Platelets Efficiently Inhibits Activated Protein C on Phosphatidylethanolamine of Platelet Membrane and Microvesicles

Cited by 41 publications

References 59 publications

Structure of Native Protein C Inhibitor Provides Insight into Its Multiple Functions

Structure of Native Protein C Inhibitor Provides Insight into Its Multiple Functions

Alboserpin, a Factor Xa Inhibitor from the Mosquito Vector of Yellow Fever, Binds Heparin and Membrane Phospholipids and Exhibits Antithrombotic Activity

Regulation of carcinoma cell invasion by protein C inhibitor whose expression is decreased in renal cell carcinoma

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