Rs2910164 in microRNA-146a confers an elevated risk of depression in patients with coronary artery disease by modulating the expression of NOS1

Depression has been well established as an independent predictor of mortality and cardiac morbidity rates in patients with coronary artery disease (CAD). Evidence has shown that single nucleotide polymorphisms located in pre-microRNA (miRNA) or mature miRNA may modify various biological processes and affect the process of carcinogenesis, and the downregulation of neuronal nitric oxide synthase 1 (NOS1) can induce depression. It has been shown that NOS1 is the target gene of miR-146a, and that the rs2910164 G/C polymorphism can downregulate the expression of miR-146a. In the present study, computational analysis was used to identify the target of miR-146a, and a luciferase reporter assay system was used to validate NOS1 as a target gene of miR-146a. In addition, U251 cells were treated with miR-146a mimics/inhibitors to verify the negative regulatory association between miR-146a and NOS1. Reverse transcription-quantitative polymerase chain reaction analysis and western blot analysis were used to estimate the mRNA expression of NOS1 and the expression of miR-146a. The results showed that the 'seed sequence' was located within the 3'-untranslated region of NOS1 by searching an online miRNA database (www.mirdb.org ), and the luciferase reporter assay confirmed that NOS1 was a direct target gene of miR-146a. It was also found that the mRNA and protein expression levels of NOS1 in U251 cells treated with miR-146a mimics and NOS1 small interfering RNA were substantially downregulated, compared with cells treated with the scramble control. The cells treated with miR-146a inhibitors showed increased expression of NOS1. In addition, the presence of a minor allele of the rs2910164 polymorphism was significantly associated with risk of depression in patients with CAD. Taken together, the findings indicated a decreased risk of depression in the patients with CAD who were carriers of the miR-146a rs2910164 C allele, and this association may be attributed to its ability to compromise the expression of miR-146a, and thereby increase the expression of its target gene, NOS1.