Investigation of the localization of dehydroepiandrosterone sulphotransferase in adult rat kidney

Sulphotransferases are a family of enzymes involved in the metabolism and d etoxification of many compounds. Dehydroepiandrosterone (DHEA) sulphotransf erase (DHEA-ST), which catalyzes the sulphation of steroids such as DHEA, i s present in rat liver and adrenals. Sulphated steroids are present in urin e, and many other enzymes which catalyze detoxification reactions are found in the kidney. There are not previous reports of DHEA-ST localization in a dult kidney. The activity of DHEA-ST was investigated in adult rat kidney b y a radioisotope assay with DHEA as the substrate. Western blotting was use d to assess protein expression, and the localization of DHEA-ST was investi gated by immunohistochemistry. The DHEA-ST activity in rat kidney was found to be approximately four times less than that in rat liver. In female kidn ey, the activity was 1.46 +/- 0.06 nmol/min/mu g, and in male kidney the ac tivity was 1.29 +/- 0.09 nmol/min/mu g. Investigation of protein expression gave a single band at 35 kDa which signified the presence of this enzyme i n both male and female adult rat kidneys. Localizat on studies showed posit ive staining at high intensity in the collecting ducts of the medulla and i n the S3 portion of the proximal convoluted tubule in the cortex. The distr ibution with in the proxima I tubules was restricted to the brush border. R everse-transcriptase polymerase chain reaction showed DHEA-ST RNA expressio n in adult rat kidney and liver. The presence of this enzyme and its locati on in the kidney may suggest that in situ sulphation via DHEA-ST may play a n important role in the excretion of endogenous and exogenous compounds, Co pyright (C) 2000 S.Karger AG,Basel.