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 prog esterone. In the cells treated with progesterone in association with 1 7 beta-estradiol, the maximum ot the S-35-labelled cell-associated mac romolecules failed to bind with an anion-exchange resin (53% of total radioactivity) and had a hydrophobic character. This fraction was sepa rated 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 re presented by cholesterol sulfate. In the progesterone-treated cells, t he amount of cholesterol sulfate was significantly higher than in 17 b eta-estradiol-treated or untreated cells (1.35-1.5-fold). Thus, the ef fect of progesterone is located on a lipophilic proteoglycan associate d with cholesterol sulfate. These results are discussed in relation to the preparation of the endometrium for embryo implantation.