Immunochemical characterization of human estrogen sulfotransferase SULT1E1 in human embryonic kidney 293 cells

Abstract

Human sulfotransferase SULT1E1 is the major cytosolic sulfotransferase isoform that catalyzes the sulfation of estrogens. This reaction increases the water solubility of the estrogen molecule, which may lead to altered cellular estrogen distribution and, as a result, may affect the cellular response to estrogenic signaling. To date, little is known about the role(s) of SULT1E1-catalyzed estrogen sulfation in the regulation of intracellular estrogen-activated signaling processes. In the current studies, the expression of SULT1E1 in human embryonic kidney 293 (HEK293) cell line was determined using immunocytochemistry and green fluorescent protein (GFP)-tagging methods. The results showed that immunoreactivity to anti-SULT1E1 antibody was highly detectable in the cytoplasm of HEK293 cells. The GFP-SULT1E1 fusion protein also had the same cytosolic location as the native protein. Additional studies using immunoblot analysis were not able to detect the expression levels of human nuclear estrogen receptors α and β in HEK293 cells. This is consistent with previous results (Thomas et. al., 2005) and suggests that the physiological role(s) of SULT1E1-catalyzed sulfation reactions in HEK293 cells are not associated with estrogen receptors α and β coupled cellular signaling pathways.