The Methylation Landscape Of Human Aortic And Mitral Valvular Interstitial Cells

Valvular interstitial cells (VICs), the predominant cell type in heart valves, play a key role in maintaining valve function, structural integrity, tissue repair, and homeostasis. DNA methylation regulates gene expression and understanding the methylation profiles of aortic and mitral VICs will enhance our knowledge of their specific biology and pathobiology. This study is the first to analyze the methylation profiles of non-diseased, matched human aortic and mitral VICs. We examined the differential methylation of 12 non-diseased VICs (10 males:2 females; 42–64 years) extracted from de-endothelialized leaflets using reduced representation bisulfite sequencing (RRBS) on HiSeq2500. Analysis of 12,676 genome-wide promoters revealed 651 differentially methylated (DM) promoters. The top three DM promoters were linked to TBX4 (meth.diff = -28.9%, P = 5.2E-135), essential for valve morphogenesis, EXOC3L2 (meth.diff = 25.7%, P = 1.3E-92), and NT5DC2 (meth.diff = -20.3%, P = 7.1E-69), which are potentially involved in extracellular matrix (ECM) remodeling. Functional classification and network analysis identified gene enrichment in WNT-, TGFβ-, FGF-, EGF-, and PDGF-pathways, important for valve development, repair, VIC regulation, and calcification. Further enrichment was noted for integrin- and cadherin-pathways involved in cell-cell and ECM interactions, and endothelin- and VEGF-pathways linked to hemodynamic regulation. This study provides crucial insights into the epigenetic regulation of aortic and mitral VICs, advancing our understanding of valve homeostasis and disease susceptibility.