Salt stress is one of the major abiotic stresses in agriculture worldwide that causes crop failure by interfering with the profile of gene expression and cell metabolism. Transcription factors and RNA-directed DNA methylation (RdDM) play an important role in the regulation of gene activation under abiotic stress in plants. This work characterized AtMYB74, a member of the R2R3-MYB gene family, which is transcriptionally regulated mainly by RdDM as a response in salt stress in Arabidopsis. Bisulphite sequencing indicated that 24-nt siRNAs target a region approximately 500bp upstream of the transcription initiation site of AtMYB74, which is heavily methylated. Levels of DNA methylation in this region were significantly reduced in wild type plants under salt stress, whereas no changes were found in RdDM mutants. Northern blot and quantitative real-time reverse transcription PCR analysis showed that the accumulation of 24-nt siRNAs was decreased in WT plants under salt stress. Further promoter deletion analysis revealed that the siRNA target region is essential for maintaining AtMYB74 expression patterns. In addition, transgenic plants overexpressing AtMYB74 displayed hypersensitivity to NaCl during seed germination. These results suggest that changes in the levels of the five 24-nt siRNAs regulate the AtMYB74 transcription factor via RdDM in response to salt stress.

TGFB2-OT1 (TGFB2 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 TGFB2-OT1 action are unclear, and whether it is involved in VECs dysfunction needs investigation. Here, the level of TGFB2-OT1 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 TGFB2-OT1 levels and inhibited the effect of LPS and oxLDL. The NUPR1 level was upregulated by the 2 inflammation inducers and modulated the TGFB2-OT1 level by promoting the expression of TIA1, responsible for TGFB2-OT1 processing. We focused on how TGFB2-OT1 regulated autophagy and inflammation. Use of miRNA chip assay, TGFB2-OT1 overexpression technology and 3BDO revealed that TGFB2-OT1 regulated the levels of 3 microRNAs, MIR3960, MIR4488 and MIR4459. Further studies confirmed that TGFB2-OT1 acted as a competing endogenous RNA, bound to MIR3960, MIR4488 and MIR4459, 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. TGFB2-OT1 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 TGFB2-OT1, and TGFB2-OT1 bound to MIR3960, MIR4488 and MIR4459, which targeted CERS1, NAT8L, and LARP1, respectively, the key proteins involved in autophagy and inflammation.

Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) are key regulators of multiple biological processes by altering gene expression at various levels. Apoptosis in vascular endothelial cells (VECs) is closely linked to numerous cardiovascular diseases, such as arteriosclerosis, thrombus formation and plaque erosion. However, studies on lncRNAs in the cardiovascular system are just beginning. And thus far, no anti-apoptosis lncRNAs have been identified in VECs. Here, we focused on the anti-apoptosis roles of lncRNAs in the serum and FGF-2 starvation-induced apoptosis of VECs. Using microarray analysis, we found a novel lncRNA LOC100129973 which acted as an apoptosis inhibitor in VECs. Through sponging miR-4707-5p and miR-4767, lncRNA LOC100129973 upregulated the expression of two apoptosis repressors gene, Apoptosis Inhibitor 5 (API5) and BCL2 like 12 (BCL2L12), and thus alleviated the serum and FGF-2 starvation-induced apoptosis in VECs. This evidence suggests that lncRNA LOC100129973 is an attractive target to improve endothelial function and for therapy of apoptosis related cardiovascular diseases.

Key points: The enzyme phosphatidylcholine‐specific phospholipase C (PC‐PLC) participates in atherosclerosis development and may negatively regulate autophagy. Phosphatidylethanolamine binding protein 1 (PEBP1) represents a novel effector of signal transduction pathways that control cellular growth, motility, apoptosis, genomic integrity, and therapeutic resistance. The disruption of PEBP1 was reported to associate with a wide range of diseases, such as cancer, pancreatitis, and Alzheimer's disease, making it a potential target for disease therapy. However, the roles of PEBP1 in vascular endothelial cell (VEC) autophagy and arteriosclerosis are not clear. Here we report that PEBP1 interacts with PC‐PLC and positively regulates PC‐PLC activity, while both PEBP1 and PC‐PLC negatively regulate VEC autophagy. The PEBP1 level is elevated during the development of atherosclerosis, and the PC‐PLC inhibitor D609 significantly decreases the upregulated PEBP1 level in apolipoprotein E^−/− mice, suggesting that PEBP1 may be a potential diagnostic indicator for atherosclerosis. Abstract  We previously found that phosphatidylcholine‐specific phospholipase C (PC‐PLC) was a key inducing element of atherosclerosis, and might negatively regulate human umbilical vein endothelial cell (HUVEC) autophagy. To further investigate the mechanism of PC‐PLC action, we initially identified phosphatidylethanolamine binding protein 1 (PEBP1) as a binding partner of PC‐PLC by using mass spectrometry (MS, MALDI‐TOF/TOF). We found that PEBP1 positively regulated PC‐PLC activity in HUVECs, and inhibition of PC‐PLC by its inhibitor D609 suppressed PEBP1 expression dramatically. Moreover, both PC‐PLC and PEBP1 negatively regulated HUVEC autophagy independently of mammalian target of rapamycin (mTOR). Furthermore, the PEBP1 level was elevated during the development of atherosclerosis, while D609 significantly decreased the upregulated PEBP1 level in apoE^−/− mice.

Low temperature is one of the major abiotic stresses limiting the productivity and geographical distribution of many important crops. To identify proteins associated with chilling stress in Nicotiana tabacum cv. bright yellow-2 (BY-2) cell suspension culture, we utilized a proteomic approach with two-dimensional electrophoresis to compare proteins from samples of treated with or without chilling treatment at 4 °C. One protein specifically more abundant in chilling treated sample was identified and designated as NtLEA7-3. Rapid amplification of cDNA ends gave rise to a full-length NtLEA7-3 cDNA with a complete open reading frame of 1267 bp, encoding a 322 amino acid polypeptide. Homology search and sequence multi-alignment demonstrated that the deduced NtLEA7-3 protein sequence shared a high identity with LEA-like proteins from other plants. Subcellular localization analysis indicated that the NtLEA7-3 was localized exclusively in the nucleus. When the gene was overexpressed in bright yellow-2 cells, the transgenic bright yellow-2 cells show more resistant to chilling stress than the wild-type cells. In addition, transgenic Arabidopsis plants overexpressing the NtLEA7-3 are much more resistant to cold, drought, and salt stresses. Interestingly, the expression of NtLEA7-3 in tobacco was not tissue-specific and induced by chilling, drought and salt stresses. All of these, taken together, suggest that NtLEA7-3 is worthwhile to elucidate the contribution of the proteins to the tolerance mechanism to chilling stress, and can be considered as a potential target for crop genetic improvement in the future.