Evidence for Regulation of HBEGF Biosynthesis by MicroRNA in Response to Hypoxia in the Human Trophoblast

Thursday, October 11, 2012 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center, Building 45	NICHD	sRNA-3

Authors

• C.V Jain
• P Jessmon
• BA Kilburn
• DR Armant

Abstract

Previous work has demonstrated that heparin-binding EGF-like growth factor (HBEGF) is upregulated in trophoblast cells cultured at low (2%) O2 without a change in HBEGF mRNA, suggesting the hypothesis that HBEGF is translationally regulated. MicroRNAs (miRNAs) are short non-coding RNA species processed by the nuclear proteins Drosha and DGCR8 that regulate translation by targeting the 3’ untranslated region (3’UTR) of specific mRNAs. The role of miRNA in regulating translation of HBEGF mRNA was examined using DGCR8 knockdown by siRNA transfection into HTR-8/SVneo human first trimester trophoblast cells. HBEGF quantified by ELISA did not increase when DGCR8 was knocked down at 20% O2, indicating that high O2 does not repress HBEGF expression through miRNA. However, the upregulation of HBEGF at 2% O2 was specifically inhibited, suggesting a miRNA-mediated activation mechanism. To determine if the 3’UTR of HBEGF mediates translational regulation, a dual luciferase reporter construct containing the intact HBEGF 3’UTR or specific subregions was implemented. The intact 3’UTR reduced luciferase activity, the isolated 5’ and 3’ flanking regions of the 3’UTR and re-introduction of the central domain increased reporter activity, suggesting that miRNA alters the interaction between inhibitory elements in the 3’UTR central domain and flanking elements that activate HBEGF translation.

back to top