Abstract
Purpose :
Structural and functional studies have implicated vitronectin (VTN), a human blood and extracellular matrix (ECM) protein, in the complex pathogenesis of age-related macular degeneration (AMD). Our aim was to further explore the role of this protein in AMD and the functional impact of the non-synonymous polymorphism rs704C>T in the VTN gene, significantly associated with AMD in a genome-wide association study (GWAS).
Methods :
Based on the largest AMD GWAS dataset of the International AMD Genomics Consortium (IAMDGC), we performed an association analysis to refine the relationship of rs704 with AMD clinical subtypes in 16,144 cases and 17,832 controls. In vitro studies including protein interaction and activity assays, western blot analysis and immunofluorescence staining were conducted to investigate the effects of rs704 on VTN function, with a focus on the interaction of recombinant VTN isoforms (AMD risk-associated VTN_rs704:T and non-risk-associated VTN_rs704:C) with the binding partner and angiogenic regulator plasminogen activator inhibitor 1 (PAI-1), and their influence on PAI-1 production by cultured endothelial and retinal pigment epithelium (RPE) cells. In addition, a large-scale gene expression analysis was performed based on our retinal gene expression database (n=311) and the Genotype-Tissue Expression (GTEx) project (n=556).
Results :
Our statistical analysis revealed an association of rs704 only with neovascular AMD (NVAMD; Q value <0.05). In in vitro assays, VTN_rs704:T showed a stronger binding to PAI-1 than VTN_rs704:C (1.50 ± 0.61-fold increase, p <0.05), while both isoforms equally sustained PAI-1 activity. Interestingly, exposure of endothelial and RPE cells to VTN isoforms resulted in a large accumulation of PAI-1 in the ECM compared to control-treated cells (p <0.05). In silico, gene expression of VTN and PAI-1 showed positive correlations and a statistically significant increase in human retinal and blood tissues aged 60 years and older.
Conclusions :
Our findings link VTN function to the progression of NVAMD and suggest a mechanism whereby ageing and the AMD-associated rs704 variant may concomitantly alter angiogenesis-related processes regulated by VTN and PAI-1. This provides novel cues to understand NVAMD, eventually facilitating the development of target-based therapeutic options to prevent and cure the vascular complications in AMD.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.