Moghrabi N, Head J R, Andersson S
Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas 75235, USA.
J Clin Endocrinol Metab. 1997 Nov;82(11):3872-8. doi: 10.1210/jcem.82.11.4391.
The enzymatic actions of the 17 beta-hydroxysteroid dehydrogenase (17 beta HSD) isozymes are crucial in steroid hormone metabolism/physiology. The type 1 isozyme catalyzes the conversion of the biologically inactive C18 steroid, estrone, to the active estrogen, 17 beta-estradiol, and the enzyme is predominantly expressed in the syncytiotrophoblast of the placenta and the granulosa cells of the ovary. 17 beta HSD type 2 is highly expressed in placenta, liver, and secretory endometrium and catalyzes the conversion of bioactive estrogens and androgens to biologically inactive 17-ketosteroid counterparts. The expression pattern of 17 beta HSD type 2 protein was determined in human term placenta and fetal liver by immunohistochemical analysis using monoclonal antibodies directed against distinct epitopes of the 17 beta HSD type 2 protein. In placenta, the protein was detected in the endothelial cells of fetal capillaries, but not in cytotrophoblasts or syncytiotrophoblast. There was dichotomous immunostaining seen among pairs of cotyledonary vessels and chorionic vessels. In the liver, on the other hand, staining was detected in the hepatocytes, but not in the cells lining blood vessels. We conclude that the cell type-specific localization of 17 beta HSD type 2 is in accord with the proposed physiological role of the enzyme, namely to protect tissues, in this case the fetus, from bioactive estrogen and androgen.
17β-羟类固醇脱氢酶（17βHSD）同工酶的酶促作用在类固醇激素代谢/生理学中至关重要。1型同工酶催化生物活性较低的C18类固醇雌酮转化为活性雌激素17β-雌二醇，该酶主要在胎盘的合体滋养层细胞和卵巢的颗粒细胞中表达。2型17βHSD在胎盘、肝脏和分泌期子宫内膜中高度表达，催化生物活性雌激素和雄激素转化为生物活性较低的17-酮类固醇对应物。通过使用针对2型17βHSD蛋白不同表位的单克隆抗体进行免疫组织化学分析，确定了2型17βHSD蛋白在人足月胎盘和胎儿肝脏中的表达模式。在胎盘中，该蛋白在胎儿毛细血管的内皮细胞中检测到，但在细胞滋养层或合体滋养层中未检测到。在成对的绒毛叶血管和绒毛膜血管中观察到二分免疫染色。另一方面，在肝脏中，在肝细胞中检测到染色，但在血管内衬细胞中未检测到。我们得出结论，2型17βHSD的细胞类型特异性定位与该酶的推测生理作用一致，即保护组织（在这种情况下是胎儿）免受生物活性雌激素和雄激素的影响。
