Effects of oestrone sulphate, oestradiol and progesterone on protein sulphation in the guinea-pig uterus

Abstract

Ovariectomized guinea-pigs were treated with oestradiol-17 beta (ES), oestrone sulphate (E1S) and progesterone (P) and the in-vitro incorporation of 35SO4 was studied in uterine fragments. The net uptake of 35O4 into tissue was only increased by oestradiol-17 beta plus progesterone. The incorporation of 35SO4 in the tissue-associated proteins was increased after treatment with E2 and E1S compared with untreated controls (3.1- and 2.5-fold, respectively). For secreted proteins, all hormone treatments induced an increase in protein sulphation, the highest increase occurring when progesterone was administered after oestrogens. Tyrosine 35SO4 was identified in protein extracts from tissues and media and values were greater after hormone treatments. The biggest increase in tyrosine 35SO4 was observed in secreted proteins in the E1S + P treatment group. The patterns of 35S-sulphate-labelled proteins were examined by SDS-polyacrylamide gel electrophoresis. In tissue extracts, the most striking differences related to the hormone treatments were observed in the Mr 94,000-190,000 region. A sulphated protein band of Mr 102,000 was specifically found in the E2 + P group and a band of Mr 125,000 only in the E1S + P group. The Mr 125,000 band was also found in tissue proteins from the E1S + P-treated animals after the incorporation of 35SO4 in vivo. This protein band may be a marker of the action of oestrone sulphate plus progesterone. For secreted proteins, those with a molecular weight greater than 100,000 were more abundant in the oestrogen plus progesterone-treated groups than in the oestrogen-treated groups. The content of tyrosine sulphate in each protein band ranged from 8 to 25% of the total radioactivity. No protein sulphated exclusively on the tyrosine residues was found. These studies provide the first description of the effects of steroid hormones on sulphated proteins in the guinea-pig uterus and suggest that oestrone sulphate is a potent biologically active hormone in the uterus.