Dehydroepiandrosterone Sulfate (DHEAS) Stimulates the First Step in the Biosynthesis of Steroid Hormones

Abstract

Dehydroepiandrosterone sulfate (DHEAS) is the most abundant circulating steroid in human, with the highest concentrations between age 20 and 30, but displaying a significant decrease with age. Many beneficial functions are ascribed to DHEAS. Nevertheless, long-term studies are very scarce concerning the intake of DHEAS over several years, and molecular investigations on DHEAS action are missing so far. In this study, the role of DHEAS on the first and rate-limiting step of steroid hormone biosynthesis was analyzed in a reconstituted in vitro system, consisting of purified CYP11A1, adrenodoxin and adrenodoxin reductase. DHEAS enhances the conversion of cholesterol by 26%. Detailed analyses of the mechanism of DHEAS action revealed increased binding affinity of cholesterol to CYP11A1 and enforced interaction with the electron transfer partner, adrenodoxin. Difference spectroscopy showed K d-values of 40±2.7 µM and 24.8±0.5 µM for CYP11A1 and cholesterol without and with addition of DHEAS, respectively. To determine the K d-value for CYP11A1 and adrenodoxin, surface plasmon resonance measurements were performed, demonstrating a K d-value of 3.0±0.35 nM (with cholesterol) and of 2.4±0.05 nM when cholesterol and DHEAS were added. Kinetic experiments showed a lower Km and a higher kcat value for CYP11A1 in the presence of DHEAS leading to an increase of the catalytic efficiency by 75%. These findings indicate that DHEAS affects steroid hormone biosynthesis on a molecular level resulting in an increased formation of pregnenolone.

2β- and 16β-hydroxylase activity of CYP11A1 and direct stimulatory effect of estrogens on pregnenolone formation

“…1A). The purified CYP11A1 showed the characteristic 289 absorbance peak at 450 nm after CO binding by the dithionite 290 reduced protein representing the stable Fe II(CO)of the purified protein calculated from the 293 CO-difference spectrum was 712 AE 63 nmol/l E. coli cell culture, 294 which represents the highest published value for this protein to 295 date(Table 1) and is also in the range of our recent publication 296 (640 nmol/l)[30]. The improved yield reflects the advantages of 297 E. coli C43(DE3) strain as an expression host together with the 298 co-expression of molecular chaperones.299 4.2.…”

“…Therefore, the conjugation 27 and deconjugation of steroids constitutes a further mechanism 28 that controls the availability of free steroids on a cellular level [9]. Q2 29 The biosynthesis of steroid hormones starts with the side-chain 30 cleavage of cholesterol producing pregnenolone. This is the first 31 enzymatic and rate-limiting step and is catalyzed by the side-chain 32 cleaving cytochrome P450CYP11A1 [10,11], a mitochondrial cyto- 33 chrome P450 found primarily in the steroidogenic cells of the 34 adrenal cortex and the gonads as well as in the skin and brain [12].…”

“…Therefore, the CYP11A1 activity 477 should not be considerably altered in the presence of the utilized 478 cyclodextrin concentration. 479 In order to investigate whether steroid intermediates have an 480 influence on the CYP11A1-dependent pregnenolone formation, in 481 vitro conversion experiments were carried out using 15 mM 482 cholesterol, which corresponds to the K m -value of CYP11A1 and 483 cholesterol[30]. At this substrate concentration the enzyme 484 exhibits its half-maximal velocity, allowing the sensitive monitorthe presence of different concentrations of either 493 estrone or estradiol revealed that the latter one is the more potent 494 activator, exhibiting a stimulation of the CYP11A1 activity at a 495 concentration as low as 5 mM(Fig.…”

Abiraterone acetate, exemestane or the combination in postmenopausal patients with estrogen receptor-positive metastatic breast cancer

“…The AA-induced increases in serum progesterone concentrations observed in all patients may have attenuated any antitumor activity due to androgen biosynthesis inhibition in this study. AA-mediated inhibition of androgen biosynthesis may lead to a subsequent diversion into the progesterone synthetic pathway via adrenal dehydroepiandrosterone and pregnenolone [ 11 ]. AA-induced elevated progesterone concentrations could then provide a growth stimulus through the PR or through other mechanisms [ 12 – 14 ].…”

Follicular fluid dehydroepiandrosterone sulfate is a credible marker of oocyte maturity and pregnancy outcome in conventional in vitro fertilization cycles

“…Although sulfonated steroids have been predominantly regarded to function as inactive storage reservoirs for steroid hormones;[ 17 18 19 20 ] it may be speculated that the sulfate group of DHEA-s plays a role in this maturation process. Indeed, in a recent study Neunzig and Bernhardt, 2014,[ 21 ] noted that DHEA-s stringently regulates the first step of steroidogenesis and surmised that the negatively charged sulfate group of DHEA-s upregulates the catalytic activity of enzyme CYP11A1 by 75% which binds with higher efficiency to substrate cholesterol to display a 26% increase in pregnenolone formation in presence of DHEA-s but not in presence of DHEA. [ 21 ] Earlier, Liu and Dillon, 2002[ 22 ] had identified a putative membrane receptor for DHEA/DHEA-s suggesting that they may possess some physiological role.…”