Forkhead box C2 Promoter Variant c.-512C.T Is Associated with Increased Susceptibility to Chronic Venous Diseases
No Thumbnail Available
Date
2014-03
Journal Title
Journal ISSN
Volume Title
Publisher
PLoS ONE.
Abstract
Chronic venous disease (CVD) is one of the most prevalent yet underrated disorders worldwide. High heritability estimates
of CVD indicate prominent genetic components in its etiology and pathology. Mutations in human forkhead box C2 (FoxC2)
gene are strongly associated with valve failure in saphenous and deep veins of lower extremities. We explored the
association of genetic variants of FoxC2 as well as FoxC2 mRNA and protein expression levels with CVD of lower limbs. We
systematically sequenced the single coding exon, 59 and 39 flanking regions of FoxC2 gene in 754 study subjects which
includes 382 patients with CVD and 372 healthy subjects. Four novel and three reported polymorphisms were identified in
our cohort. Three variants in 59 flanking region and one in 39 flanking region of FoxC2 gene were significantly associated
with CVD risk. FoxC2 mRNA in vein tissues from 22 patients was 461.42 fold increased compared to saphenous veins from
20 normal subjects (p,0.01). FoxC2 protein was also significantly upregulated in varicose veins compared to control
samples. The c.-512C.T (rs34221221: C.T) variant which is located in the FoxC2 putative promoter region was further
analyzed. Functional analysis of c.-512C.T revealed increased mRNA and protein expression in patients with homozygous
TT genotype compared to heterozygous CT and wild CC genotypes. Luciferase assay indicated higher transcriptional activity
of mutant compared to wild genotype of this variant. These findings suggested that c.-512C.T variant of FoxC2 was
strongly associated with susceptibility to CVD and also that this variant resulted in FoxC2 overexpression. To obtain a
mechanistic insight into the role of upregulated FoxC2 in varicosities, we overexpressed FoxC2 in venous endothelial cells
and observed elevated expression of arterial markers Dll4 and Hey2 and downregulation of venous marker COUP-TFII. Our
study indicates altered FoxC2-Notch signaling in saphenous vein wall remodeling in patients with varicose veins.
Description
Keywords
Citation
PLoS ONE. 2014;9(3):1-9