The aim of the present research was to study the uptake of DHEAS, and to establish the intracrine capacity of human platelets to produce sex steroid hormones. The DHEAS transport was evaluated through the uptake of [3 H]-DHEAS in the presence or absence of different substrates through the organic anion transporting polypeptide (OATP) family. The activity of sulfatase enzyme was evaluated, and the metabolism of DHEAS was measured by the conversion of [3 H]-DHEAS to [ 3 H]-androstenedione, [3 H]-testosterone, [3 H]-estrone and [ 3 H]-17β-estradiol. Results indicated the existence in the plasma membrane of an OATP with high affinity for DHEAS and estrone sulphate (E1 S). The platelets showed the capacity to convert DHEAS to active DHEA by the steroid-sulfatase activity. The cells resulted to be a potential site for androgens production, since they have the capacity to produce androstenedione and testosterone; in addition, they reduced [3 H]-estrone to [3 H]-17β- estradiol. This is the first demonstration that human platelets are able to import DHEAS and E1 S using the OATP family and to convert DHEAS to active DHEA, and to transform E1 S to 17β- estradiol., A. Garrido ... [et al.]., and Obsahuje seznam literatury
Steroid sulfatase (EC 3.1.6.2) is an important enzyme involved in steroid hormone metabolism. It catalyzes the hydrolysis of steroid sulfates into their unconjugated forms. This action rapidly changes their physiological and biochemical properties, especially in brain and neural tissue. As a result, any imbalance in steroid sulfatase activity may remarkably influence physiological levels of active steroid hormones with serious consequences. Despite that the structure of the enzyme has been completely resolved there is still not enough information about the regulation of its expression and action in various tissues. In the past few years research into the enzyme prope ties and regulations has been strongly driven by the discovery of its putative role in the indirect stimulation of the growth of hormone-dependent tumors of the breast and prostate., L. Kříž, M. Bičíková, R. Hampl., and Obsahuje bibliografii a bibliografické odkazy