ScholarWorks@숙명여자대학교

초록

The considerable atheroprotection afforded by statins (HMG-CoA reductase inhibitors) is thought to be above and beyond that expected from their cholesterol lowering capabilities, which is known as statin pleiotropy. Endothelial microRNAs are emerging as key mediators of cellular functions that can dictate vascular homeostasis. We hypothesized that statins induce differential expression of microRNAs in endothelial cells, which may define novel signaling pathways by which statins exert their pleiotropic effects. We carried out a microRNA expression array using HUVECs subjected to treatment with simvastatin. Of endothelial microRNAs that are differentially regulated in response to statin, we found that miR-335 was the most significantly downregulated, in a KLF2 dependent manner. MiR-335 overexpression was found to increase expression of inflammatory markers in the endothelial cells and augment monocyte adhesion. These effects were mediated by miR-335 induced NF-κB activation, as demonstrated by significantly increased NF-κB reporter activity in cells overexpressing miR-335. To identify potential mechanism by which miR-335 regulates NF-κB activation, we conducted a gene expression profile analyses and cross-referenced the down-regulated genes in our expression profiling analyses with those genes that are predicted to be targeted by miR-335-5p. We identified CHFR (checkpoint with forkhead and ring finger domain) as a direct 3’ UTR target of miR-335, which in turn negatively regulates NF-κB activity. Similar to the effect of miR-335 overexpression, CHFR silencing led to significant increase expression of inflammatory markers in the endothelial cells, which was mediated by CHFR silencing induced NF-κB activation. Finally, in vivo analysis using miR335 deficient mice found them to be metabolically protected, and on the Apoe deficient background found that these mice were protected against high fat diet induced atherosclerosis (Figure 1). Overall, we identify miR-335 as a critical microRNA downregulated by statins that potentiates a number of pro-inflammatory signaling sequelae and may define an important node in statin pleiotropy.

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