SEARCH:   Advanced

Prepublished online as a Blood First Edition Paper on April 17, 2002; DOI 10.1182/blood-2001-12-0237. This Article Full Text (PDF) All Versions of this Article: 2001-12-0237v1 99/10/3602    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Francischetti, I. M Articles by Ribeiro, J. M Search for Related Content PubMed PubMed Citation Articles by Francischetti, I. M Articles by Ribeiro, J. M Social Bookmarking                   What's this? Submitted December 13, 2001 Accepted January 16, 2002 Ixolaris, a Novel Recombinant Tissue Factor Pathway Inhibitor (TFPI) From the Salivary Gland of the Tick, Ixodes scapularis: Identification of Factor X and Factor Xa as Scaffolds for the Inhibition of Factor VIIa/Tissue Factor Complex Ivo M Francischetti, Jesus G Valenzuela, John F Andersen, Thomas N Mather, and Jose M Ribeiro* Section of Medical Entomology, Laboratory of Parasitic Diseases, Natioal Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA Center for Vector-Borne Disease, University of Rhode Island, Kingston, RI, USA * Corresponding author; email: jribeiro{at}nih.gov. Saliva of the hard tick and Lyme disease vector, Ixodes scapularis, has a repertoire of compounds that counteracts host defenses. Following sequencing of an I. scapularis salivary gland cDNA library, a clone with sequence homology to tissue factor pathway inhibitor (TFPI) was identified. This cDNA codes for a mature protein, herein called Ixolaris, with 140 amino acids containing 10 cysteines and two Kunitz-like domains. Recombinant Ixolaris was expressed in insect cells and shown to inhibits FVIIa (FVIIa)/Tissue Factor (TF)-induced Factor X (FX) activation with an IC50 in the pM range. In non-denaturing gel, Ixolaris was shown to interact stoichiometrically with FX and FXa but not FVIIa. Ixolaris behaves as a fast-and-tight ligand of the exosites of FXa and des-Gla-FXa (-carboxyglutamic acid domainless FXa), increasing its amidolytic activity. At high concentration, Ixolaris attenuates the amidolytic activity of FVIIa/TF; however, in the presence of the DEGR-FX or DEGR-FXa (but not des-Gla-DEGR-FXa), Ixolaris becomes a tight inhibitor of FVIIa/TF as assessed by recombinant Factor IX (BeneFIX) activation assays. This indicates that FX and FXa are scaffolds for Ixolaris in the inhibition of FVIIa/TF and implies that the Gla-domain is necessary for FVIIa/TF /Ixolaris/FX(a) complex formation. Additionally, we show that Ixolaris blocks FXa generation by endothelial cells expressing TF. Ixolaris may be a useful tool to study the structural features of FVIIa, FX, and FXa, and/or an alternative anticoagulant in cardiovascular diseases. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: Y. Decrem, G. Rath, V. Blasioli, P. Cauchie, S. Robert, J. Beaufays, J.-M. Frere, O. Feron, J.-M. Dogne, C. Dessy, et al. Ir-CPI, a coagulation contact phase inhibitor from the tick Ixodes ricinus, inhibits thrombus formation without impairing hemostasis J. Exp. Med., October 26, 2009; 206(11): 2381 - 2395. [Abstract] [Full Text] [PDF] D. Ma, Y. Wang, H. Yang, J. Wu, S. An, L. Gao, X. Xu, and R. Lai Anti-thrombosis Repertoire of Blood-feeding Horsefly Salivary Glands Mol. Cell. Proteomics, September 1, 2009; 8(9): 2071 - 2079. [Abstract] [Full Text] [PDF] X. Guo, C. J. Booth, M. A. Paley, X. Wang, K. DePonte, E. Fikrig, S. Narasimhan, and R. R. Montgomery Inhibition of Neutrophil Function by Two Tick Salivary Proteins Infect. Immun., June 1, 2009; 77(6): 2320 - 2329. [Abstract] [Full Text] [PDF] S. M. Ceraul, S. M. Dreher-Lesnick, A. Mulenga, M. S. Rahman, and A. F. Azad Functional Characterization and Novel Rickettsiostatic Effects of a Kunitz-Type Serine Protease Inhibitor from the Tick Dermacentor variabilis Infect. Immun., November 1, 2008; 76(11): 5429 - 5435. [Abstract] [Full Text] [PDF] M. Kotsyfakis, J. M. Anderson, J. F. Andersen, E. Calvo, I. M. B. Francischetti, T. N. Mather, J. G. Valenzuela, and J. M. C. Ribeiro Cutting Edge: Immunity against a "Silent" Salivary Antigen of the Lyme Vector Ixodes scapularis Impairs Its Ability to Feed J. Immunol., October 15, 2008; 181(8): 5209 - 5212. [Abstract] [Full Text] [PDF] X. Xu, H. Yang, D. Ma, J. Wu, Y. Wang, Y. Song, X. Wang, Y. Lu, J. Yang, and R. Lai Toward an Understanding of the Molecular Mechanism for Successful Blood Feeding by Coupling Proteomics Analysis with Pharmacological Testing of Horsefly Salivary Glands Mol. Cell. Proteomics, March 1, 2008; 7(3): 582 - 590. [Abstract] [Full Text] [PDF] E. Calvo, F. Tokumasu, O. Marinotti, J.-L. Villeval, J. M. C. Ribeiro, and I. M. B. Francischetti Aegyptin, a Novel Mosquito Salivary Gland Protein, Specifically Binds to Collagen and Prevents Its Interaction with Platelet Glycoprotein VI, Integrin {alpha}2beta1, and von Willebrand Factor J. Biol. Chem., September 14, 2007; 282(37): 26928 - 26938. [Abstract] [Full Text] [PDF] A. Sa-Nunes, A. Bafica, D. A. Lucas, T. P. Conrads, T. D. Veenstra, J. F. Andersen, T. N. Mather, J. M. C. Ribeiro, and I. M. B. Francischetti Prostaglandin E2 Is a Major Inhibitor of Dendritic Cell Maturation and Function in Ixodes scapularis Saliva J. Immunol., August 1, 2007; 179(3): 1497 - 1505. [Abstract] [Full Text] [PDF] P.-P. Prevot, B. Adam, K. Z. Boudjeltia, M. Brossard, L. Lins, P. Cauchie, R. Brasseur, M. Vanhaeverbeek, L. Vanhamme, and E. Godfroid Anti-hemostatic Effects of a Serpin from the Saliva of the Tick Ixodes ricinus J. Biol. Chem., September 8, 2006; 281(36): 26361 - 26369. [Abstract] [Full Text] [PDF] N. Kato, T. Okayama, H. Isawa, M. Yuda, Y. Chinzei, and S. Iwanaga Contribution of the N-Terminal and C-Terminal Domains of Haemaphysalin to Inhibition of Activation of Plasma Kallikrein-Kinin System J. Biochem., September 1, 2005; 138(3): 225 - 235. [Abstract] [Full Text] [PDF] S. Narasimhan, R. R. Montgomery, K. DePonte, C. Tschudi, N. Marcantonio, J. F. Anderson, J. R. Sauer, M. Cappello, F. S. Kantor, and E. Fikrig Disruption of Ixodes scapularis anticoagulation by using RNA interference PNAS, February 3, 2004; 101(5): 1141 - 1146. [Abstract] [Full Text] [PDF] J. G. Valenzuela, I. M. B. Francischetti, V. M. Pham, M. K. Garfield, T. N. Mather, and J. M. C. Ribeiro Exploring the sialome of the tick Ixodes scapularis J. Exp. Biol., September 15, 2002; 205(18): 2843 - 2864. [Abstract] [Full Text] [PDF]

	Copyright © 2002 by American Society of Hematology         Online ISSN: 1528-0020