Short communication: a mutation in the 3' untranslated region diminishes microRNA binding and alters expression of the OLR1 gene

The oxidized low-density lipoprotein (lectin-like) receptor 1 (OLR1) gene plays an important role in the degradation of the oxidized low-density lipoprotein, which causes damage to the arterial endothelium. Previous studies have shown that a single nucleotide polymorphism (SNP) in the 3' untranslated region (UTR) of OLR1 was associated with milk production and health traits in dairy cattle and with loin eye area and marbling depth in Qinchuan beef cattle. However, the mechanisms by which this SNP affects these traits are not well understood. MicroRNA (miRNA or mir) are small noncoding RNA that regulate gene expression by binding to target mRNA at their UTR to degrade or to repress translation of the target transcript. We hypothesized that miRNA bind to the 3' UTR of OLR1 to cause expression changes of the gene. To test this hypothesis, the Bos taurus autosome (bta)-mir-370miRNA was selected for this study based on bioinformatics prediction analysis. Two vectors that included A or C nucleotides of the 3' UTR SNP and 1 control vector were co-transfected with the vector of bta-miR-370 into human embryonic kidney 293 (HEK293) cells. Results of the dual-luciferase reporter assay showed that the activity of luciferase was significantly lower in cells transfected with the A nucleotide vector than that of the C nucleotide and control vectors. The assay also indicated that activity of miRNA bta-mir-370 was associated with a differential allelic regulation of OLR1 expression. These results imply that the 3' UTR SNP of the OLR1 gene is a strong candidate marker for selection in cattle breeding programs.