Abstract 157: Inkiln is a Novel Long Noncoding RNA Promoting Vascular Smooth Muscle Inflammation Via Scaffolding Mkl1 and Usp10

Abstract

Activation of vascular smooth muscle cells (VSMCs) inflammation is critical in initiation and progression of vascular disease. However, the role of human-specific long noncoding RNAs (lncRNAs) in VSMC inflammation is largely unknown. We performed Bulk RNA-seq in differentiated human VSMCs and revealed a novel human-specific lncRNA called IN flammatory M K L1 I nteracting L ong N oncoding RNA ( INKILN ). INKILN is barely expressed in contractile VSMCs or healthy vessels and induced in human atherosclerosis and abdominal aortic aneurysm. INKILN is transcriptionally activated through p65/NF-κB pathway. INKILN activates proinflammatory gene expression in cultured human VSMCs and in ex vivo cultured vessels. Mechanistically, INKILN physically binds to and stabilizes MKL1 protein, a key activator of VSMC inflammation through the p65/NF-κB pathway. In the IL1β-activated VSMCs, depletion of INKILN blocks the nuclear localization of both p65 and MKL1, and abolishes the physical interaction between these two proteins, resulting in the reduced transactvity of p65/NF-κB. Further, INKILN knockdown enhances MKL1 ubiquitination, likely through the reduced physical interaction with the deubiquitinating enzyme USP10. The in vivo study of INKILN has utilized a Bacterial Artificial Chromosome (BAC) INKILN -Transgenic (Tg) mouse line, due to the lack of non-conserved INKILN gene in the mouse genome. In the ligation-injured carotid arteries of BAC INKILN -Tg mice, human lncRNA INKILN is induced and has exacerbated neointimal formation. In conclusion, these findings elucidate an important pathway of VSMC inflammation involving an INKILN /MKL1/USP10 regulatory axis. Human BAC Tg mice offer a novel and physiologically relevant approach for investigating human-specific lncRNAs under vascular disease conditions.