Abstract 100: The Non-Conserved Long Noncoding RNA, RP11-184M15.1, Regulates Macrophage Phenotype and Associates with Human Coronary Atherosclerosis

Macrophage activation and dysfunction promote atherosclerosis and its clinical complications. Functional long noncoding RNAs (lncRNAs) are emerging as important modulators of macrophage biology. The human genome, however, encodes thousands of lncRNAs that are yet to be characterized, most of which are not conserved in mouse. Through RNA-seq of human monocyte-derived macrophages, we identified 2,776 multi-exon long intergenic noncoding RNAs (lincRNAs), and found RP11-184M15.1 , a non-conserved, macrophage-specific lncRNA, to be highly induced during M2 (IL-4) activation, but suppressed in the M1 (LPS/IFNγ) phenotype ( Figure ), suggesting that RP11-184M15.1 may regulate macrophage activation and metabolic functions. 5’ and 3’ RACE revealed a single 2-exon isoform, and ChIP-seq showed PU.1 and C/EBPβ binding at the RP11-184M15.1 TSS. RP11-184M15.1 was localized primarily in macrophage cytoplasm. To test roles of RP11-184M15.1 in macrophage activation, we induced knockdown (KD) or overexpression (OE) of RP11-184M15.1 in THP1 human macrophages by transfection of siRNAs and transduction of full-length RP11-184M15.1 packaged lentivirus respectively, and then stimulated with IL-4. In preliminary studies, OE of RP11-184M15.1 reduced expression of CCL13 , MMP12 , and MRC1 while KD increased levels of MMP12 . Given its cytoplasmic localization, we used DIANA lncBase tool and identified miR-5088-3p, miR-6516-5p and miR-16-5p, known to modulate inflammatory macrophages, as top miRNAs predicted to interact with RP11-184M15.1. Of clinical relevance, RP11-184M15.1 was expressed in healthy human coronary arteries, but suppressed in coronary atherosclerotic lesions. In summary, RP11-184M15.1 is a human, non-conserved, macrophage-specific lncRNA that modulates macrophage phenotype and is suppressed in atherosclerosis.