Sulfation of vitamin D -related compounds-identification and characterization of the responsible human cytosolic sulfotransferases.

While 25-hydroxyvitamin D 3-O-sulfate is known to be present in circulation, how it is generated in the body remains unclear. This study aimed to investigate its sulfation in major human organs and to unveil the responsible cytosolic sulfotransferases (SULTs). Of the vitamin D -related compounds tested, 25-hydroxyvitamin D and 7-dehydrocholesterol are preferentially sulfated by human organ cytosols. Among the 13 human SULTs, SULT2A1 shows sulfating activity toward all vitamin D -related compounds, whereas SULT1A1 and SULT2B1a/SULT2B1b show sulfating activity exclusively for, respectively, calcitriol and 7-dehydrocholesterol. These findings suggest that the metabolic pathway leading to the formation of 25-hydroxyvitamin D 3-O-sulfate may be mediated by the sulfation of 25-hydroxyvitamin D or by the conversion of 7-dehydrocholesterol-3-O-sulfate in the skin.