Abstract 12052: Estrogen-mediated Regulation of MiR-183/96/182 Cluster Processing in the Vasculature
Estradiol (E2) directly regulates the biology and function of cells and tissues within the cardiovascular system partially by activating E2 receptor alpha (ERα) and beta and regulating target genes expression. We have previously shown that E2 down-regulates many genes in vascular cells. Though the molecular mechanisms by which E2 increases gene expression are understood in some detail, the molecular mechanisms that mediate E2-induced down-regulation of genes are currently unknown. MiRs are small noncoding RNAs that primarily repress gene expression post-transcriptionally. We hypothesized that E2 regulates miRs that in turn repress target genes in the vasculature. We have recently identified a set of miRs that are regulated by E2 in the mouse aorta by performing miR microarray, and demonstrated that E2-mediated miR expression is responsible for down-regulation of specific genes in vascular cells. In the current study, we focused our attention on the miR-183-96-182 cluster, which was significantly up-regulated by E2 in mouse aorta, and studied this miR cluster further in cultured vascular smooth muscle cell (VSMC). Transient transfection assays showed that E2 via ERα significantly up-regulated mature and precursor miR-183, 96, and 182 but had no effect on primary miRs. We then further hypothesized that E2 via ERα regulates Drosha-mediated processing of miR-183-96-182 cluster in VSMC. Co-IP assays demonstrated complex formation between ERα and Drosha and that E2 treatment enhances ERα-Drosha complex formation. The interaction region of ERα required for complex formation with Drosha was mapped to the fragment from amino acid 176 to 253 by GST and His tag pull-down assays. Mutation analyses support that ERα amino acid residues 231, 233, and 234 play a critical role in mediating ERα and Drosha binding. Moreover, over-expression of miR-182 and miR-183, individual or combined, specifically inhibited VSMC proliferation in vitro, though these miRs had no effect on vascular endothelial cell growth. In conclusion, our findings provide the first evidence that the liganded ERα regulates miR cluster processing by interacting with Drosha in VSMC and are indicative of an important role of miR-183-96-182 cluster in E2-mediated regulation of vascular cell function.
- © 2012 by American Heart Association, Inc.