Abstract 18234: miR-362-3p Decreases hERG Expression and is Associated With an Unidentified Form of Congenital Long-QT Syndrome

Abstract

Introduction: Endogenous microRNAs (miRs) regulate cardiovascular disease by modulating diverse cellular processes. We recently discovered that miRs may mediate the association between a single nucleotide polymorphism (rs1533317) and QT interval prolongation; identified in a previous genome-wide association study (GWAS). The objective of this research was to assess the ability of the identified miRs to regulate the expression of hERG (i.e. KCNH2). Methods: Through a previous genome-wide integrated miR-transcriptome analysis, the expression of 9 miRs were significantly associated with rs1533317 (p< 1x10 -5 ). To assess this relationship further, a correlation analyses between transcriptome and miRNome data was performed related to the down-regulation of KCNH2. The potential targeting of KCNH2 by miR was validated using a Dual-Luciferase Assay of the KCNH2 3′-UTR. SK-Br-3 cells were co-transfected with miR mimic or negative control and the KCNH2-3’UTR reporter clone. The reporter plasmid, renilla, was used to control for transfection efficiency. To further assess the ability of miRs to down-regulate KCNH2, SK-Br-3 cells (endogenous KCNH2 expression) were transfected with miR mimic or control and KCNH2 protein expression was assessed by Western blot analysis. Results: Out of the 9 assessed, miRs 362-3p, 98, 148, 129*, and 186 were significantly associated with down-regulation of KCNH2 based on the transcriptome and miRNome data (p<0.001). From the Luciferase assay, miR-362-3p was the only miR to significantly reduce KCNH2 3’UTR activity (mean ± SE of 42.6% ± 16.9) relative to control, whereas KCNH2 3’UTR activity was enhanced by miR-98 by an unknown mechanism (figure). Endogenous KCNH2 protein expression was reduced by 33.9% ± 5.3 relative to GAPDH by miR 362-3p (p=0.01). Conclusion: Upregulation of miR-362-3p decreases KCNH2 expression and may be the underlying mechanism for a previously reported unidentified form of LQTS regulated by rs1533317.