Page 219 - Haematologica - Vol. 105 n. 6 - June 2020

Hemostasis
LIM-only protein FHL2 attenuates vascular tissue factor activity, inhibits thrombus formation in mice and FHL2 genetic variation associates with human venous thrombosis
Chantal Kroone,1 Mariska Vos,2 Timo Rademakers,3 Marijke Kuijpers,4 Mark Hoogenboezem,3 Jaap van Buul,3 Johan W.M. Heemskerk,4 Wolfram Ruf,5,6 Astrid van Hylckama Vlieg,7 Henri H. Versteeg,1 Marie-José Goumans,8 Carlie J.M. de Vries,2# and Kondababu Kurakula;2,8# INVENT Consortium
1The Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center (UMC), Leiden, the Netherlands; 2Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; 3Department of Molecular Cell Biology, Sanquin Research, Amsterdam, the Netherlands; 4Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht UMC, Maastricht, The Netherlands; 5Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA; 6Center for Thrombosis and Hemostasis Mainz, Germany; 7Department of Clinical Epidemiology, Leiden UMC, Leiden, the Netherlands and 8Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
#CMdV and KK contributed equally as co-senior authors.
ABSTRACT
Bleeding disorders and thrombotic complications are major causes of morbidity and mortality with many cases being unexplained. Thrombus formation involves aberrant expression and activation of tissue factor (TF) in vascular endothelial and smooth muscle cells. Here, we sought to identify factors that modulate TF gene expression and activity in these vascular cells. The LIM-only protein FHL2 is a scaffold- ing protein that modulates signal transduction pathways with crucial functions in endothelial and smooth muscle cells. However, the role of FHL2 in TF regulation and thrombosis remains unexplored. Using a murine model of venous thrombosis in mesenteric vessels, we demon- strated that FHL2 deficiency results in exacerbated thrombus formation. Gain- and loss-of-function experiments revealed that FHL2 represses TF expression in endothelial and smooth muscle cells through inhibition of the transcription factors nuclear factor κB and activating protein-1. Furthermore, we observed that FHL2 interacts with the cytoplasmic tail of TF. In line with our in vivo observations, FHL2 decreases TF activity in endothelial and smooth muscle cells whereas FHL2 knockdown or defi- ciency results in enhanced TF activity. Finally, the FHL2 single nucleotide polymorphism rs4851770 was associated with the risk of venous throm- bosis in a large population of venous thrombosis cases and control sub- jects from 12 studies (INVENT consortium). Altogether, our results high- light functional involvement of FHL2 in TF-mediated coagulation and identify FHL2 as a novel gene associated with venous thrombosis in humans.
Introduction
Thrombosis is a common pathology underlying venous thromboembolism (VTE), as well as ischemic heart disease and ischemic stroke, and is a leading cause of morbidity and mortality worldwide.1 Thrombus formation involves platelet activation and aggregation as well as local, vascular tissue factor (TF) expression and activation, which may result in occlusion of blood vessels and ischemic events.2-6 The expression of TF, a transmembrane protein, is highly induced in both vascular smooth muscle cells (SMC) and endothelial cells (EC) in response to
Ferrata Storti Foundation
Haematologica 2020 Volume 105(6):1677-1685
Correspondence:
KONDABABU KURAKULA k.b.kurakula@lumc.nl
Received: July 25, 2018. Accepted: August 26, 2019. Pre-published: August 29, 2019.
doi:10.3324/haematol.2018.203026
Check the online version for the most updated information on this article, online supplements, and information on authorship & disclosures: www.haematologica.org/content/105/6/1677
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