A Long Non-Coding RNA Enhances Endothelial NO Bioavailability through Chromatin Remodeling
Presentation Number: LB SUN 32
Date of Presentation: April 2nd, 2017
Beckman Research Institute, City of Hope, Duarte, CA
Serving as a bioactive interface between the blood flow and the vessel wall, the vascular endothelium senses mechanical and chemical signals under various physiological and pathophysiological conditions, such as atherosclerosis (hyperlipidemia), hypertension, and diabetes (hyperglycemia). Most, if not all, of these conditions affect endothelial NO synthase (eNOS), the endothelial hallmark molecule, through (post-) transcriptional and/or (post-) translational modulations. Despite the extensive studies on these mechanisms, it is unclear whether and how chromatin remodeling plays a role in regulation of eNOS. In this study, we explored the role of long non-coding RNAs (lncRNAs)-mediated chromatin remodeling in eNOS expression. Combining transcriptome RNA-sequencing and circularized chromosome conformation capture (4C) sequencing, we identified in human endothelial cells (ECs) a long non-coding RNA (lncRNA) that positively correlates with eNOS at the transcriptional level and directly interacts with eNOS promoter at the genomic level. Mechanistically, this lncRNA acts as a scaffold to enhance eNOS transcription through mediating the long-range DNA interaction and transcription factor binding, thus termed ‘lncRNA-enhancing endothelial NOS’ (LEEN). Multiple endothelium-impairing factors, including athero-prone flow, pro-inflammatory cytokine tumor necrosis factor a (TNFa), and hyperglycemia, reduce LEEN expression, with attendant decrease in eNOS expression. Mimicking LEEN suppression in these conditions through locked nucleic acid-GapmerRs or CRISPR-Cas9-mediated genomic editing leads to decreases in eNOS level. Complementarily, gain-of-function assay demonstrates that over-expression of LEEN promotes eNOS and NO production from ECs. Collectively, LEEN plays an essential role in eNOS expression through chromatin remodeling, and consequently in NO bioactivity and EC homeostasis. We anticipate that the identification of LEEN can have significant impacts on understanding of diseases involving endothelial dysfunction, such as diabetes complications and tumorigenesis.
Nothing to Disclose: YM