title: Factor Xa is a fibroblast mitogen via binding to effector-cell protease receptor-1 and autocrine release of PDGF.
abstract: The coagulation cascade protease thrombin is a fibroblast mitogen, but the proliferative potential of other coagulation proteases is not known. In this study we show that factor Xa stimulated human fetal lung fibroblast DNA synthesis in a concentration-dependent manner from 1 nM onward with a fourfold increase at 200 nM. The mitogenic effect of factor Xa was confirmed using a colorimetric proliferation assay and direct cell counting. Factor Xa and thrombin had equivalent potencies, and their stimulatory effects followed a similar time course. Comparable results were also obtained with primary human adult fibroblasts derived from lung, kidney, heart, skin, and liver. Factor VIIa also stimulated fibroblast proliferation, but only at concentrations >10 nM, whereas factor IXa had no effect. To begin to address the mechanism by which factor Xa is acting, we show that human fibroblasts express effector-cell protease receptor-1 and that blocking antibodies to this receptor and the catalytic site of factor Xa inhibited its mitogenic effect. Furthermore, factor Xa upregulated platelet-derived growth factor-A (PDGF-A) mRNA expression, whereas PDGF-B could not be detected, and a blocking antibody to PDGF inhibited the mitogenic effect of factor Xa. We conclude that factor Xa acts as a fibroblast mitogen via binding to effector-cell protease receptor-1 and the autocrine release of PDGF.
authors.affiliation: Centre for Cardiopulmonary Biochemistry and Respiratory Medicine, Royal Free and University College Medical School, The Rayne Institute, London WC1E 6JJ, United Kingdom. oblancbrude@hotmail.com
authors.forename: O P
authors.initials: OP
authors.lastname: Blanc-Brude
authors.forename: R C
authors.initials: RC
authors.lastname: Chambers
authors.forename: P
authors.initials: P
authors.lastname: Leoni
authors.forename: W A
authors.initials: WA
authors.lastname: Dik
authors.forename: G J
authors.initials: GJ
authors.lastname: Laurent
mesh_terms: D000328:Adult; D019898:Autocrine Communication / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects; D015949:Factor IXa / Q000494:pharmacology; D015942:Factor VIIa / Q000494:pharmacology; D015951:Factor Xa / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008297:Male; D008934:Mitogens / Q000378:metabolism / Q000502:physiology*; D010447:Peptide Hydrolases / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism* / Q000502:physiology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D000077022:Survivin; D013917:Thrombin / Q000494:pharmacology
chemical_list: C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008934:Mitogens; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D000077022:Survivin; D010447:Peptide Hydrolases; D015942:Factor VIIa; D015949:Factor IXa; D013917:Thrombin; D015951:Factor Xa