Effect of progesterone on hydrophobic cell-associated proteoglycans bound to cholesterol sulfate in glandular epithelial cells of guinea-pig endometrium.

Sulfate incorporation was studied in subcultured glandular epithelial cells of guinea-pig endometrium untreated or treated with 10(-8) M 17 beta-estradiol alone or associated with various concentrations of progesterone. In the cells treated with progesterone in association with 17 beta-estradiol, the maximum of the 35S-labelled cell-associated macromolecules failed to bind with an anion-exchange resin (53% of total radioactivity) and had a hydrophobic character. This fraction was separated as an aggregate when the cells were extracted with 4 M guanidine-HCl, and separated as a single component in the presence of Triton X-100, suggesting that it aggregates with cellular lipid. The guanidine-extracted material contained 23.5% proteoglycans. However, the bulk of the radioactivity was in the sulfated lipids (68-75%), essentially represented by cholesterol sulfate. In the progesterone-treated cells, the amount of cholesterol sulfate was significantly higher than in 17 beta-estradiol-treated or untreated cells (1.35-1.5-fold). Thus, the effect of progesterone is located on a lipophilic proteoglycan associated with cholesterol sulfate. These results are discussed in relation to the preparation of the endometrium for embryo implantation.