The potential atheroprotective role of plant MIR156a as a repressor of monocyte recruitment on inflamed human endothelial cells

MicroRNAs have become the spotlight of the biological community for more than a decade, but we are only now beginning to understand their functions. The detection of stably expressed endogenous microRNAs in human blood suggests that these circulating miRNAs can mediate intercellular communication. Our previous study reported the surprising finding that exogenous rice MIR168a could regulate liver low-density lipoprotein receptor adapter protein 1 (LDLRAP1) gene expression in mice. Here, we show that plant MIR156a, which is abundantly expressed in dietary green veggies, also stably presents in healthy human serum. Compared with age-matched individuals, decreased levels of MIR156a are observed both in serum and blood vessel of cardiovascular disease (CVD) patients. In vitro studies demonstrate that MIR156a can directly target the junction adhesion molecule-A (JAM-A), which is up-regulated in atherosclerotic lesions from CVD patients. Functional studies show that ectopic expression of MIR156a in human aortic endothelial cells reduces inflammatory cytokine-induced monocytes adhesion by suppressing JAM-A. These findings offer a novel vasoprotective molecular mechanism of green veggies through plant microRNAs.