Assembly and expression of an intrinsic factor IX activator complex on the surface of cultured human endothelial cells.
نویسندگان
چکیده
Endothelial cells expose specific receptors for blood clotting factors and, upon perturbation, can initiate and propagate the reactions of the extrinsic pathway of blood coagulation leading to fibrin formation on the cell surface. The existence of an intrinsic mechanism of Factor IX activation on cultured human umbilical vein cells (HUVECs) was investigated by studies of the interaction between HUVECs and two proteins of the contact activation system, the cofactor high molecular weight kininogen (H-kininogen) and the zymogen Factor XI. In the presence of zinc ions (10-300 microM), 125I-labeled H-kininogen bound to HUVECs in a time-dependent, reversible, and saturable manner, with calcium ions exerting an inhibitory effect on the zinc-dependent binding. Analysis of the binding data by the LIGAND computer program indicated that HUVECs, in the presence of 2 mM CaCl2 and 100 microM ZnCl2 at 37 degrees C, bound 1.14 x 10(7) H-kininogen molecules per cell with an apparent dissociation constant of 55 nM. HUVEC-bound H-kininogen functions as the cell surface receptor for both 125I-labeled Factor XI and 125I-labeled Factor XIa, since HUVECs cultured in contact factor-depleted serum do not detectably bind either the zymogen or the enzyme in the absence of H-kininogen and zinc ions. In the presence of saturating concentrations of H-kininogen, 2 mM CaCl2 and 100 microM ZnCl2, the binding of 125I-labeled Factor XI and Factor XIa to HUVECs was time-dependent, reversible, and saturable, with apparent dissociation constants of 4.5 and 1.5 nM, respectively. HUVEC-bound complexes of H-kininogen and Factor XI generated Factor XIa activity only after the addition of purified Factor XIIa, and cell-bound Factor XIa in turn activated Factor IX, as documented by a 3H-labeled activation peptide release assay for 3H-Factor IX activation. The results indicate that cultured HUVECs provide a surface for the assembly and expression of an intrinsic Factor IX activator complex that may participate in the initiation of blood coagulation at sites of vascular injury.
منابع مشابه
Effect of Purification of Human Adipose-derived Mesenchymal Stem Cells on the Expression of vWF Cell Factor Under Chemical and Mechanical Conditions
Introduction: Human adipose-derived mesenchymal stem cells (hADSCs) are easily accessible in the body, and under appropriate conditions, they can be directed toward various phenotypes. Therefore, hADSCs have been considered as a potential cell source for tissue engineering applications. hADSCs are able to differentiate into endothelial cells which covers the interior surface of vessels, in vi...
متن کاملAnti-angiogenic Effects of Metformin, an AMPK Activator, on Human Umbilical Vein Endothelial Cells and on Granulation Tissue in Rat
Objective(s)Metformin is well known for activation of AMP-activated protein kinase (AMPK). AMPK activation inhibits mammalian target of rapamycin (mTOR) as a key signaling process in cell proliferation. Recent epidemiological studies demonstrate that metformin lowers the risk for several types of cancer in diabetic patients. Concerning the critical role of angiogenesis in the incidence and prog...
متن کاملPatterns of Vascular Endothelial Growth Factor Expression in Hematopoietic Malignant Cells
Background and Objective: Vascular endothelial growth factor (VEGF) is a cytokine which is overexpressed in many malignant cancers including leukemia. VEGF plays an important role in tumor invasion and metastasis. Determination of the pattern of VEGF expression in human leukemic cell lines could be useful not only in screening of new antileukemic agents but also to study the mechanism of their ...
متن کاملExpression of Recombinant Coagulation Factor IX in Human Amniotic Membrane-derived Mesenchymal Stem Cells: A New Strategy to Gene Therapy of Hemophilia B
Background: Hemophilia B is an X-linked hereditary disorder of blood coagulation system which is caused by factor IX (FIX) deficiency. Factor IX is a plasma glycoprotein that participates in the coagulation process leading to the generation of fibrin. Replacement of factor IX with plasma-derived or recombinant factor IX is the conventional treatment for hemophilia B to raise the factor IX le...
متن کاملFunctions of the Heterologous Intron-Derived Fragments Intra and Extra Factor IX-cDNA Coding Region on the Human Factor IX Expression in HepG2 and Hek-293T Cells
Background: Human FIX (hFIX) gene transfer into hepatocytes has provided a novel approach for treatment of hemophilia B. To obtain an improved expression of hFIX, the functional hFIX-expressing plasmids with appropriate intron-derived fragments which facilitate transcription and promote an efficient 3′-end formation of mRNAs are required.Objectives: We ai...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of biological chemistry
دوره 267 28 شماره
صفحات -
تاریخ انتشار 1992