Localization and variable expression of Gαi2 in human endometrium and Fallopian tubes

Background: Heterotrimeric G proteins take part in membrane-mediated cell signalling and have a role in hormonal regulation. This study clarifies the expression and localization of the G protein subunit Gαi2 in the human endometrium and Fallopian tube and changes in Gαi2 expression in human endometrium during the menstrual cycle. Methods: The expression of Gαi2 was identified by Polymerase chain reaction (PCR), and localization confirmed by immunostaining. Cyclic changes in Gαi2 expression during the menstrual cycle were evaluated by quantitative real-time PCR. Results: We found Gαi2 to be expressed in human endometrium, Fallopian tube tissue and in primary cultures of Fallopian tube epithelial cells. Our studies revealed enriched localization of Gαi2 in Fallopian tube cilia and in endometrial glands. We showed that Gαi2 expression in human endometrium changes significantly during the menstrual cycle, with a higher level in the secretory versus proliferative and menstrual phases (P < 0.05). Conclusions: Gαi2 is specifically localized in human Fallopian tube epithelial cells, particularly in the cilia, and is likely to have a cilia-specific role in reproduction. Significantly variable expression of Gαi2 during the menstrual cycle suggests Gαi2 might be under hormonal regulation in the female reproductive tract in vivo. © 2007 Oxford University Press.postprin

Hormonal regulation of Gα i2 and mPRα in immortalized human oviductal cell line OE-E6/E7

Heterotrimeric G proteins play a key role in membrane-mediated cell-signalling and hormonal regulation. Our earlier studies gave evidence of G protein subunit Gα i2 being under hormonal regulation in human in vivo. In this study, we used immortalized human oviduct epithelial cell line OE-E6/E7 as a model to study the hormonal regulation of Gα i2. We aimed at clarifying whether estradiol or progesterone could individually regulate the expression of Gα i2 and its potential signalling partners. Furthermore, we aimed to investigate which sex hormone receptors could potentially mediate the gene regulation in OE-E6/E7 cell line. OE-E6/E7 cells were cultured for 5 days with different concentrations of estradiol or progesterone. Quantitative real-time polymerase chain reaction (Q-PCR) was performed using cDNA of the hormone-treated cells to reveal any changes in gene expression. The presence of potential receptor targets in these cells was studied using PCR. Our data clearly showed that low concentrations of estradiol up-regulated the expression of Gα i2 gene and down-regulated the expression of membrane progesterone receptor mPRα gene in OE-E6/E7 cell line. Progesterone had no significant effect on Gα i2 gene expression, but it caused up-regulation of mPRα gene expression. In conclusion, it appears that sex hormones regulate the expression of Gα i2 and mPRα genes in a reverse manner in OE-E6/E7 cells. Our results suggest that estrogen receptor ERβ mediates the regulatory effects of estradiol in these cells. © The Author 2007. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.link_to_subscribed_fulltex