Truncated SRA RNA derivatives inhibit estrogen receptor-a-mediated transcription.

Molecular biology reports

PubMedID: 27406387

Jung E, Jang S, Lee J, Kim Y, Shin H, Park HS, Lee Y. Truncated SRA RNA derivatives inhibit estrogen receptor-a-mediated transcription. Mol Biol Rep. 2016;.
The steroid receptor RNA activator (SRA) is a long non-coding RNA (lncRNA) that acts as a putative coactivator for steroid receptor-mediated transcription. A recent study showed that SRA RNA can be structurally dissected into four domains comprising various secondary structures, but the contribution of each domain to the coactivation ability of SRA RNA was previously unknown. Here, we assessed the functional contributions of the various domains of SRA. We examined the effects of each domain on the coactivation of estrogen receptor-a (ERa)-mediated transcription of a luciferase reporter gene in HeLa cells. Then the detailed domain analysis was focused on domain III (D3) not only with the reporter gene in HeLa cells, but also with ERa-responsive genes in MCF7 breast cancer cells. Domain deletion analysis showed that the deletion of any domain decreased the luciferase activity, and that deletion of D3 caused the largest decrease. This D3 deletion effect was not recovered by co-expression of D3 alone; moreover, the expression of D3 fragments (particularly helices H15-H18, which are highly conserved across vertebrates) inhibited luciferase expression in HeLa cells. Moreover, a fragment containing helices H15-H18 reduced ERa-responsive gene expression in MCF7 breast cancer cells. Our findings indicate that D3 inhibited ERa-mediated transcription of a reporter gene in HeLa cells and that helices H15-H18, as a core element responsible for the D3-driven inhibition, reduced expression of ERa-responsive genes in breast cancer cells.