OP-16 - Mechanosensitive miR-320a and miR-21-3p regulate Bach1 expression in endothelial cells

Endothelial cells (EC) in athero-prone regions and athero-protected regions respectively experience low, oscillatory (OS) and high unidirectional (US) fluid shear stress (FSS). Reduced activity of the antioxidant transcription factor Nrf2 in EC exposed to OS may contribute to oxidative stress and lesion formation. Our previous work using human umbilical vein EC (HUVEC) demonstrated that cells exposed to US (15 dyn/cm2) exhibited enhanced Nrf2 expression and activation of downstream antioxidant genes compared to cells exposed to OS (±5 dyn/cm2), concomitant with reduced expression of its competitive inhibitor Bach1. Furthermore, miRNA-320a levels are elevated in HUVEC exposed to US whilst miRNA-21-3p is enhanced by OS. We show that EaHy926 cells cultured under FSS exhibit comparable Nrf2 responses and miRNA patterns to HUVEC. EC were transfected with miRNA-21-3p and miRNA-320a mimics, and effects on protein and mRNA expression of Nrf2, its regulatory proteins and downstream targets were assessed. Bach1 protein levels were enhanced by miR-21-3p and reduced by miR-320a. Our findings suggest that these mechanosensitive miRNAs may regulate EC redox phenotype by modulating the Nrf2 antioxidant signaling pathway in response to FSS.