The human placenta expresses multiple glucocorticoid receptor isoforms that are altered by fetal sex, growth restriction and maternal asthma.

INTRODUCTION

We have previously identified sex-specific differences in the fetal-placental response to cortisol. Our recent studies suggest that this differential response to cortisol is driven by differences in glucocorticoid receptor (GR) protein function rather than through changes in gene transcription or protein expression.

METHODS

This study was designed to define whether the human placenta expresses different isoforms of the GR and whether expression was altered by fetal sex and maternal asthma. Asthma and non-asthma pregnant women were prospectively recruited at their first antenatal visit and placentae collected at delivery. Placental GR expression was examined in relation to maternal asthma, fetal sex and birthweight.

RESULTS

Twelve specific bands for the GR were identified at molecular weights of 94, 91, 81, 74, 69, 68, 65, 60, 55, 50, 48 and 38 kDa. The 12 isoforms were localised to the placental trophoblast and expression varied in relation to cellular location in either the cytoplasm or nucleus, fetal sex, fetal size and the presence and absence of maternal asthma.

CONCLUSION

This is the first study to identify the presence of several protein isoforms of the GR in the human placenta. The data suggest glucocorticoid resistance observed in male placentae may be mediated through increased GRβ, GR A and GR P localisation to the nucleus. While female placentae may be more sensitive to cortisol in the presence of maternal asthma through a decrease in GRβ and an enhancement GRα activity via an interaction with GRα D3 and GRα C.