Estrogen and hydroxysteroid sulfotransferases in guinea pig adrenal cortex: cellular and subcellular distributions

This report describes for the first time the cellular and subcellular localization of estrogen sulfotransferase (EST) as well as the subcellular localization of hydroxysteroid sulfotransferase (HST) in the mammalian adrenal cortex. A 34-kilodalton EST and two HSTs with 3 alpha- and 3 beta-hydroxysteroid substrate specificities (32 and 33 kilodaltons, respectively) were previously purified from guinea pig adrenal cortex and characterized. Western blots were used to establish that two antisera generated against EST were highly specific for EST, whereas three antisera generated against the HSTs were highly specific for the HSTs, but did not distinguish between the 3 alpha- and 3 beta HSTs. Light and electron microscopic immunoperoxidase labeling with these antisera revealed that the sulfotransferases were expressed only within the ACTH-responsive layers of the guinea pig adrenal cortex, with EST localized to zona fasciculata and zona reticularis cells, and the HSTs confined to the zona reticularis. No labeling was detected in the zona glomerulosa or adrenal medulla. EST was concentrated in cell nuclei; sparse labeling was distributed throughout the cytoplasm. HST labeling was intense in smooth endoplasmic reticulum of zona reticularis cells, but was absent from nuclei. Ovoid inclusions about 1-4 microns in diameter, with no limiting membrane, were observed in zona reticularis cells; these inclusions were strongly labeled for both EST and HSTs. No gender-specific differences in distribution or labeling intensity were apparent. The high concentration of EST immunoreactivity in nuclei suggests that EST may play a role in modulating the ability of active estrogens to regulate gene expression in ACTH-responsive cells. The distribution of HST labeling suggests that sulfonation of adrenocortical 3-hydroxysteroids takes place largely within smooth endoplasmic reticulum in the zona reticularis in adult guinea pigs.