ORIGINAL ARTICLESOverexpression of glycosyl phosphatidylinositol-anchored tissue factor pathway inhibitor-1 inhibits tissue factor activityOtt, Ilka; Vukovich, Ruth; Albert Schömig, ; Neumann, Franz-JosefAuthor Information Deutsches Herzzentrum und 1. Medizinische Klinik der Technischen Universität München, Germany. Sponsorship: The study was supported in part by grants from the Deutsche Forschungsgemeinschaft (Ot/4-1), the Gesellschaft für Thrombose und Hämostaseforschung and the Bayerische Wissenschaftsministerium (Bayerischer Habilitationsförderpreis I.O.). Correspondence and requests for reprints to Dr I. Ott, 1. Medizinische Klinik und Deutsches Herzzentrum, Technische Universität München, Lazarettstr. 36, 80636 München, Germany. Tel: +49 89 1218 2504; fax: +49 89 1218 4013; e-mail: firstname.lastname@example.org Received 23 October 2002 Revised 2 February 2003 Accepted 5 February 2003 Blood Coagulation & Fibrinolysis: September 2003 - Volume 14 - Issue 6 - p 539-544 Buy Abstract The cellular initiation of coagulation by the tissue factor (TF)-activated factor VII complex is transiently inhibited by endogenous tissue factor pathway inhibitor-1 (TFPI-1), whereas exogenously added TFPI-1 is targeted to a degradation pathway. This study investigates the relevance of glycosyl phosphatidylinositol (GPI) anchoring for the anticoagulant properties of TFPI-1. Experiments were performed with the human cell line ECV304 using liposomal gene transfer. For GPI anchoring of TFPI-1 we used a fusion protein of TFPI-1 and the GPI attachment sequence of decay-accelerating factor (GPI–TFPI-1), and compared it with wild-type TFPI-1. We measured TF and TFPI-1 surface expression by flow cytometry and TF proteolytic activity by a chromogenic assay for activated factor X generation. After transfection of GPI–TFPI-1, surface expression of TFPI-1 increased to 134 ± 9% of mock transfected cells (mean ± SEM, P = 0.004), and transfection with wild-type TFPI-1 did not significantly alter TFPI-1 surface expression. After transfection with GPI–TFPI-1, TF activity was reduced by 18 ± 9% compared with mock transfections (P = 0.003), whereas after transfection with TFPI-1 wild type no significant inhibition was observed. This effect was not due to altered TF expression. GPI anchoring is an essential prerequisite for surface expression of TFPI-1 and inhibition of TF activity. Gene transfer of GPI-anchored TFPI, therefore, may be an efficient tool to inhibit local TF-induced coagulation. © 2003 Lippincott Williams & Wilkins, Inc.