Expression of cystic fibrosis transmembrane conductance regulator in human endometrium

BACKGROUND: As a cAMP-regulated Cl- channel, cystic fibrosis transmembrane conductance regulator (CFTR) plays a critical role in the active secretion of electrolytes and fluid in epithelial cells. Women with CFTR gene mutations are less fertile, generally assumed to be due to cervical factors. However, there is little known about CFTR protein expression in human endometrium and its possible roles in reproduction. METHODS AND RESULTS: CFTR protein and mRNA levels in human endometrium were analysed using immunohistochemical and in situ hybridization methods, respectively. Significant expression of CFTR protein was only seen in the glandular cells from late proliferative to all secretory phases, consistent with western blot analysis. High levels of CFTR mRNA were present only around the ovulatory period. In cultured glandular cells, the production of CFTR protein and mRNA was stimulated by estradiol and inhibited by progesterone. A forskolin-activated Cl- current in endometrial epithelial cells with a linear I-V relationship was detected by the whole-cell patch-clamp technique. CONCLUSIONS: (i) CFTR mRNA and protein were localized in human endometrial epithelial cells and the amounts varied in a cyclic manner; (ii) CFTR expression in cultured glandular cells was up- and downregulated by estradiol and progesterone, respectively; and (iii) CFTR in human endometrium functions as a cAMP-activated Cl- channel.