Splice variants of lncRNA RNA ANRIL exert opposing effects on endothelial cell activities associated with coronary artery disease.

Each gene typically has multiple alternatively spliced transcripts. Different transcripts are assumed to play a similar biological role; however, some transcripts may simply lose their function due to loss of important functional domains. Here, we show that two different transcripts of lncRNA gene ANRIL associated with coronary artery disease (CAD) play antagonizing roles against each other. We previously reported that DQ485454, the short transcript, is downregulated in coronary arteries from CAD patients, and reduces monocyte adhesion to endothelial cells (ECs) and transendothelial monocyte migration (TEM). Interestingly, the longest transcript NR_003529 is significantly upregulated in coronary arteries from CAD patients. Overexpression of ANRIL transcript NR_003529 increases monocyte adhesion to ECs and TEM, whereas knockdown of NR_003529 expression reduces monocyte adhesion to ECs and TEM. Much more dramatic effects were observed for the combination of overexpression of NR_003529 and knockdown of DQ485454 or the combination of knockdown of NR_003529 and overexpression of DQ485454. The antagonizing effects of ANRIL transcripts NR_003529 and DQ485454 were associated with their opposite effects on expression of downstream target genes EZR, CXCL11 or TMEM106B. Our results demonstrate that different transcripts of lncRNA can exert antagonizing effects on biological functions, thereby providing important insights into the biology of lncRNA. The data further support the hypothesis that ANRIL is the causative gene at the 9p21 CAD susceptibility locus.

Androgen inhibits key atherosclerotic processes by directly activating ADTRP transcription.

Low androgen levels are associated with an increased risk of coronary artery disease (CAD), thrombosis and myocardial infarction (MI), suggesting that androgen has a protective role. However, little is known about the underlying molecular mechanism. Our genome-wide association study identified the ADTRP gene encoding the androgen-dependent TFPI regulating protein as a susceptibility gene for CAD and MI. The expression level of ADTRP was regulated by androgen, but the molecular mechanism is unknown. In this study, we identified the molecular mechanism by which androgen regulates ADTRP expression and tested the hypothesis that androgen plays a protective role in cardiovascular disease by activating ADTRP expression. Luciferase assays with an ADTRP promoter luciferase reporter revealed that androgen regulated ADTRP transcription in a dose- and time-dependent manner, and the effect was abolished by three different androgen inhibitors, including pyrvinium pamoate, bicalutamide, and cyproterone acetate. Chromatin-immunoprecipitation showed that the androgen receptor bound to a half androgen response element (ARE, TGTTCT) located at +324bp from the ADTRP transcription start site. The ARE is required for concentration-dependent transcriptional activation of ADTRP. HL-60 monocyte adhesion to EAhy926 endothelial cells (ECs) and transmigration across the EC layer, the two processes critical to development of CAD and MI, were inhibited by androgen, but the effect was rescued by ADTRP siRNA and exacerbated by overexpression of ADTRP and its downstream genes PIK3R3 and MIA3. These data suggest that one molecular mechanism by which androgen confers protection against CAD is stimulation of ADTRP expression.

3-(3-Hydroxyphenyl)propionic acid, a microbial metabolite of quercetin, inhibits monocyte binding to endothelial cells via modulating E-selectin expression.

Adhesion of monocytes to endothelial cells is an important initiating step in atherogenesis. One of the most abundant flavonoids in the diet, quercetin has been reported to inhibit monocyte adhesion to endothelial cells. However, it is poorly absorbed in the upper gastrointestinal tract during oral intake but rather is metabolized by the intestinal microbiota into various phenolic acids. Since the biological properties of the microbial metabolites of quercetin remain largely unknown, herein, we investigated how the microbial metabolite of quercetin, 3-(3-hydroxyphenyl)propionic acid (3HPPA) impact monocyte adhesion to endothelial cells. Direct treatment with 3HPPA for 24 h was not cytotoxic to human aortic endothelial cells (HAECs). Cotreatment with 3HPPA inhibited tumor necrosis factor α (TNFα)-induced adhesion of THP-1 monocytes to HAECs, and suppressed the upregulation of cell adhesion molecule E-selectin but not intercellular adhesion molecule 1 or vascular cell adhesion molecule 1. Furthermore, 3HPPA was found to inhibit TNFα-induced nuclear translocation and phosphorylation of the p65 subunit of nuclear factor κB (NF-κB). We conclude that 3HPPA mitigates the adhesion of monocytes to endothelial cells by suppressing the expression of the cell adhesion molecule E-selectin in HAECs via inhibition of the NF-κB pathway, providing additional evidence for the health benefits of dietary flavonoids and their microbial metabolites as therapeutic agents in atherosclerosis.