EXPRESSION OF TYPE-1, TYPE-2, AND TYPE-3 17-BETA-HYDROXYSTEROID DEHYDROGENASE IN SUBCUTANEOUS ABDOMINAL AND INTRAABDOMINAL ADIPOSE-TISSUE OF WOMEN

Human adipose tissue is known to have 17 beta-oxidoreductase activity, interconverting estrone (E-1) and estradiol (E-2), as well as androst enedione (A) and testosterone (T). We examined both the subcutaneous a bdominal and intra-abdominal (visceral) adipose tissue of women for ex pression of types 1, 2, and 3 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) using ribonuclease (RNase) protection assay and RT-PCR/Sout hern blotting. Type 1 17 beta-HSD, which encodes the enzyme responsibl e for the conversion of E-1 to E-2 in the placenta and ovary, was expr essed in the subcutaneous abdominal and intra-abdominal adipose tissue of women, but the messenger RNA transcripts were predominantly incomp letely spliced and therefore unlikely to encode an active protein. A p seudogene for type 1 17 beta-HSD was also expressed in these tissues, but messenger RNA transcripts were again unspliced. Type 2 17 beta-HSD , which encodes an enzyme that can catalyze the conversion of T to A a nd E-2 to E-1, was expressed in both the subcutaneous abdominal and in tra-abdominal adipose tissue of women. Type 3 17 beta-HSD was also exp ressed in adipose tissue from both sites studied. Type 3 17 beta-HSD e ncodes the enzyme that catalyzes the conversion of A to T in the testi s and also converts E-1 to E-2. Together with aromatase, which is know n to be expressed in adipose tissue, the expression of types 2 and 3 1 7 beta-HSD indicates that sex steroid production in the adipose tissue of women is a complex process. The association of visceral obesity wi th the development of insulin resistance and dyslipidaemia raises the question of the role of steroid production in adipose tissue in the pa thogenesis of these disorders.