Introduction: Micro RNAs (miRs) are non-coding small RNAs and act as important post-transcriptional regulators of gene expression by altering the abundance or translational efficiency of mRNAs. We have identified sex differences in placental miRs expression in the presence of maternal asthma which target genes involved in cellular growth, differentiation and glucocorticoid receptor signalling. We have also previously shown that in the presence of maternal asthma both male and female fetuses exhibit differential growth response to similar concentrations of cortisol. This may be related to the differential gene regulatory mechanisms initiated by males and females in-utero for growth and survival. We hypothesise that this could be mediated by and glucocorticoid receptor (GR) expression. The aim of this study was to 1.Examine the expression of miRs (372,519b, 519c, 534, 210, 211, and 144) that target the GR and 2. Identify miR regulation of GR expression in an inflammatory environment.
Method: The trophoblast cell line BeWo was cultured and treated with either LPS (10ng/ml), cortisol (1uM) or both. Cells were also treated with media alone and vehicle control. Cells were harvested at 2 and 24 hours and total RNA and protein was extracted. Real time PCR was used to determine the mRNA levels of miRs and GR. Western blot was used to determine GR protein expression.
Results: All miRs examined were detected in BeWo cells except mir-543 and 519b. There was differential effect of cortisol and LPS on miR expression. Notably, there was significant decrease in mir-144 expression at 24hrs in the presence of LPS and cortisol but no change in GR mRNA and increased protein expression. On the contrary, cortisol alone did not change the expression of mir-144 but significantly increased GR mRNA and protein.
Conclusion: The results of this study suggests the expression of miRs can be affected by cortisol and in an inflammatory environment but the regulation of the GR mRNA could be mediated not only by mir-144 but other miRs present in the cells that target the GR and this needs to be confirmed.