Epigenetic Mechanisms Involved in Anti‐Inflammatory Actions of a Diabetes Regulated lncRNA DRAIR in Monocytes

Abstract

Type 2 diabetes (T2D) is associated with monocyte activation and chronic inflammation implicated in accelerated cardiovascular disease. Evidence shows that epigenetic mechanisms and long non‐coding RNAs (lncRNA)s can regulate inflammatory phenotype of monocytes, but their role in T2D induced monocyte dysfunction is unclear. Here, we describe the regulation and functions of a novel lncRNA Diabetes Regulated anti‐ inflammatory RNA (DRAIR) in monocytes. Using RNA‐seq we identified downregulation of several anti‐inflammatory genes and lncRNAs including DRAIR in peripheral blood CD14+ monocytes isolated from subjects with T2D versus healthy controls. Further studies showed that high glucose and palmitic acid significantly downregulated DRAIR expression in CD14+ monocytes and THP1 human monocytes. Conversely, DRAIR was upregulated by anti‐inflammatory cytokines and by PMA (inducer of macrophage differentiation). ChIP assays showed that KLF4 transcription factor binds at KLF4 binding sites in the DRAIR promoter and KLF4 overexpression upregulates DRAIR expression in monocytes. Loss and gain of function approaches revealed that DRAIR regulates anti‐inflammatory phenotype in monocytes and macrophages. Mouse orthologous Drair was also similarly downregulated in macrophages from T2D db/db mice and its knockdown with LNA‐GapmeRs increased expression of pro‐inflammatory genes. Furthermore, we found that DRAIR is a chromatin associated lncRNA. Chromatin isolation by RNA purification and RNA‐immunoprecipitation revealed DRAIR interaction with chromatin near target genes and with a histone methyl transferase G9a. Mechanistically, DRAIR overexpression inhibited G9a recruitment and enrichment of the repressive histone modification H3K9me2 at anti‐inflammatory genes. Together, these results demonstrate that DRAIR can mediate anti‐inflammatory phenotype in monocytes/macrophages via epigenetic mechanisms, and its downregulation in diabetes might contribute to mechanisms promoting chronic inflammation associated with diabetes complications.Support or Funding InformationThis research work was funded by National Institutes of Health grant NIH R01 DK 065073.