Regulatory impact of a 5'UTR resident single nucleotide variant on EDN1 gene expression and RNA-protein interactions.

Non-coding regulatory variants are gaining a lot of attention in recent years. This study identifies a 5’UTR variant of the Endothelin-1 gene (EDN1) linked to elevated production of Endothelin-1. The potent vasoactive Endothelin-1 (ET-1) peptide is implicated in vascular homeostasis. Its dysregulated production disturbs the balance between vasodilation and vasoconstriction with pathophysiological consequences including cardiovascular diseases. In an observational study with 95 CAD patients two were identified as homozygous for an insertion of ‘A’ at + 139 position of 5’UTR region of EDN1 gene. These patients exhibited elevated median plasma ET-1 levels (16.02 pg/ml), compared to 6.6 pg/ml and 3.87 pg/ml observed in patients without the insertion in the homozygous and heterozygous states, respectively. This clinical observation, uninformative statistically, was verified in vitro through reporter assays that demonstrated a significant increase in ET-1 expression. RNA affinity pull-down coupled with MS/MS was further employed to delineate differential RNA protein interactions. Proteomic profiling identified recruitment of RNA-binding proteins by the insertion variant. Collectively, these findings implicate the + 139 A insertion in the EDN1 5′-UTR as a functional non-coding variant that primarily enhances ET-1 expression through post-transcriptional mechanisms, including translation efficiency and mRNA stability, thereby influencing cardiovascular disease risk.