A new microRNA signal pathway regulated by long noncoding RNA TGFB2-OT1 in autophagy and inflammation of vascular endothelial cells

<p><i>TGFB2-OT1</i> (<i>TGFB2</i> overlapping transcript 1) is a newly discovered long noncoding RNA (lncRNA) derived from the 3′UTR of TGFB2. It can regulate autophagy in vascular endothelial cells (VECs). However, the mechanisms of <i>TGFB2-OT1</i> action are unclear, and whether it is involved in VECs dysfunction needs investigation. Here, the level of <i>TGFB2-OT1</i> was markedly increased by lipopolysaccharide and oxidized low-density lipoprotein, 2 VECs inflammation triggers. A chemical small molecule, 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO) significantly decreased <i>TGFB2-OT1</i> levels and inhibited the effect of LPS and oxLDL. The NUPR1 level was upregulated by the 2 inflammation inducers and modulated the <i>TGFB2-OT1</i> level by promoting the expression of TIA1, responsible for <i>TGFB2-OT1</i> processing. We focused on how <i>TGFB2-OT1</i> regulated autophagy and inflammation. Use of miRNA chip assay, <i>TGFB2-OT1</i> overexpression technology and 3BDO revealed that <i>TGFB2-OT1</i> regulated the levels of 3 microRNAs, <i>MIR3960, MIR4488</i> and <i>MIR4459</i>. Further studies confirmed that <i>TGFB2-OT1</i> acted as a competing endogenous RNA, bound to <i>MIR3960, MIR4488</i> and <i>MIR4459</i>, then regulated the expression of the miRNA targets CERS1 (ceramide synthase 1), NAT8L (N-acetyltransferase 8-like [GCN5-related, putative]), and LARP1 (La ribonucleoprotein domain family, member 1). CERS1 and NAT8L participate in autophagy by affecting mitochondrial function. <i>TGFB2-OT1</i> increased the LARP1 level, which promoted SQSTM1 (sequestosome 1) expression, NFKB RELA and CASP1 activation, and then production of IL6, IL8 and IL1B in VECs. Thus, NUPR1 and TIA1 may control the level of <i>TGFB2-OT1</i>, and <i>TGFB2-OT1</i> bound to <i>MIR3960, MIR4488</i> and <i>MIR4459</i>, which targeted CERS1, NAT8L, and LARP1, respectively, the key proteins involved in autophagy and inflammation.</p