Oral Presentation The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2017

Placental microRNA expression and renin-angiotensin system activity are regulated by oxygen (#22)

Anya L Arthurs 1 , Andrea Mathe 1 , Eugenie Lumbers 1 , Kirsty Pringle 1
  1. University of Newcastle, Newcastle, NSW, Australia

The renin-angiotensin system (RAS) plays an important role in placentation. Placental development which occurs in the first trimester takes place in a low oxygen environment.  At this time placental RAS expression is maximal. We have previously shown that miRNAs can  play a role in post-transcriptional regulation of the placental RAS. 

Placental oxygen levels might regulate the expression of miRNAs that target the RAS, so we aimed to show if oxygen affected the expression of these miRNAs.

HTR-8/SVneo cells (a first trimester trophoblast cell line) were cultured in 1%, 5% and 20% oxygen. Total RNA was extracted and analysed using  an Affymetrix miRNA array. The effects of oxygen on miRNA expression were validated by qRT-PCR as well as  its effects  on expression of RAS genes and proteins.

The Affymetrix miRNA microarray showed that 10 miRNAs known to target genes of the RAS pathway were differentially expressed in cells grown in 1% oxygen (compared with cells grown in 5-20%). 9 of these were validated by qRT-PCR. Culture in 1% oxygen was associated with reduced expression of all 9 miRNAs compared with cultures in 20% oxygen. Furthermore, 5 of these 9 miRNAs had lower levels of expression when cells were incubated in 1% oxygen compared with cells grown in 5% oxygen. This is significant as they are the oxygen tensions in the fetal chorionic plate and the maternal decidua respectively.

RAS genes  (ACE, AGTR1, ATP6AP2) that are targets for these 5 miRNAs were upregulated by 1% oxygen. Thus the prevailing oxygen tension regulates expression of miRNAs and the placental RAS, thus an early increase in pO2 within the developing placenta could disturb normal expression of the placental RAS and impair placental development.