Per- and polyfluoroalkyl substances inhibit human and rat 17β-hydroxysteroid dehydrogenase 1: Quantitative structure-activity relationship and molecular docking analysis

Per- and polyfluoroalkyl (PFAS) substances are enduring industrial materials. 17β-Hydroxysteroid dehydrogenase isoform 1 (17β-HSD1) is an estrogen metabolizing enzyme, which transforms estrone into estradiol in human placenta and rat ovary. Whether PFAS inhibit 17β-HSD1 and what the structure-activity relationship (SAR) remains unexplored. We screened 18 PFAS for inhibiting human and rat 17β-HSD1 in microsomes and studied their SAR and mode of action(MOA). Of the 11 perfluorocarboxylic acids (PFCAs), C8-C14 PFCAs at a concentration of 100 μM substantially inhibited human 17β-HSD1, with order of C11 (half-maximal inhibition concentration, IC50, 8.94 μM) > C10 (10.52 μM) > C12 (14.90 μM) > C13 (30.97 μM) > C9 (43.20 μM) > C14 (44.83 μM) > C8 (73.38 μM) > others. Of the 7 per- and poly-fluorosulfonic acids (PFSAs), the potency was C8S (IC50, 14.93 μM) > C7S (80.70 μM) > C6S (177.80 μM) > others. Of the PFCAs, C8-C14 PFCAs at 100 μM markedly reduced rat 17β-HSD1 activity, with order of C11 (IC50, 9.11 μM) > C12 (14.30 μM) > C10 (18.24 μM) > C13 (25.61 μM) > C9 (67.96 μM) > C8 (204.39 μM) > others. Of the PFSAs, the potency was C8S (IC50, 37.19 μM) > C7S (49.38 μM) > others. In contrast to PFOS (C6S), the partially fluorinated compound 6:2 FTS with an equivalent number of carbon atoms demonstrated no inhibition of human and rat 17β-HSD1 activity at a concentration of 100 μM. The inhibition of human and rat enzymes by PFAS followed a V-shaped trend from C4 to C14, with a nadir at C11. Moreover, human 17β-HSD1 was more sensitive than rat enzyme. PFAS inhibited human and rat 17β-HSD1 in a mixed mode. Docking analysis revealed that they bind to the NADPH and steroid binding site of both 17β-HSD1 enzymes. The 3D quantitative SAR (3D-QSAR) showed that hydrophobic region, hydrogen bond acceptor and donor are key factors in binding to 17β-HSD1 active sites. In conclusion, PFAS exhibit inhibitory effects on human and rat 17β-HSD1 depending on factors such as carbon chain length, degree of fluorination, and the presence of carboxylic acid or sulfonic acid groups, with a notable V-shaped shift observed at C11.

Light-switchable diazocines as potential inhibitors of testosterone-synthesizing 17β-hydroxysteroid dehydrogenase 3

In patients with prostate carcinoma as well as in some other cancer types, the reduction of testosterone levels is desired because the hormone stimulates cancer cell growth. One molecular target for this goal is the inhibition of 17β-hydroxysteroid dehydrogenase type 3 (17βHSD3), which produces testosterone from its direct precursor androstenedione. Recent research in this field is trying to harness photopharmacological properties of certain compounds so that the inhibitory effect could be turned on and off by irradiation. Seven new light-switchable diazocines were investigated with regard to their inhibition of 17βHSD3. For this purpose, transfected HEK-293 cells and isolated microsomes were treated with the substrate and the potential inhibitors with and without irradiation for an incubation period of 3 or 5 h. The amount of generated testosterone was measured by UHPLC and compared between samples and control as well as between irradiated and non-irradiated samples. There was no significant difference between samples with and without irradiation. However, four of the seven diazocines led to a significantly lower testosterone production both in cell and in microsome assays. In some of the irradiated samples, a partial destruction of the diazocines was observed, indicated by an additional UHPLC peak. However, the influence on the inhibition is negligible, because the majority of the substance remained intact. In conclusion, new inhibitors of 17βHSD3 have been found, but so far without the feature of a light switch, since the configurational alteration of the diazocines by irradiation did not lead to a change in bioactivity. Further modification might help to find a light-switching molecule that inhibits only in one configuration.

Characterization of eight types of 17β-hydroxysteroid dehydrogenases from the Japanese sardine Sardinops melanostictus: The probable role of type 12a in ovarian estradiol synthesis

17β-hydroxysteroid dehydrogenases (Hsd17bs) play a critical role in sex steroid biosynthesis. Although multiple types of Hsd17b have been found in fish, there is limited research on their expression and function. Recently, we succeeded in identifying eight types of Hsd17b (types 3, 4, 7, 8, 10, 12a, 12b, and 14) by RNA sequencing in the Japanese sardine Sardinops melanostictus, a commercially important clupeoid fish; however, a homologous sequence of Hsd17b1, which catalyzes the key reaction of estradiol-17β (E2) synthesis, was absent. Here, we aimed to identify the Hsd17b type that plays a major role in E2 synthesis during ovarian development in Japanese sardine. The cDNAs encoding those eight types of Hsd17b were cloned and sequenced. The expressions of hsd17b3, hsd17b12a, and hsd17b12b were higher in ovary than in testis. In particular, hsd17b12a was predominantly expressed in the ovary. Expression of hsd17b3, hsd17b4, hsd17b12a, and hsd17b12b in the ovary increased during ovarian development. The enzymatic activities of Hsd17b3, Hsd17b12a, and Hsd17b12b were evaluated by expressing their recombinants in human embryonic kidney 293T cells. Hsd17b12a and Hsd17b12b catalyzed the conversion of androstenedione (AD) to testosterone (T) and estrone (E1) to E2. The results of in vitro bioassays using sardine ovaries indicated that E2 is synthesized from pregnenolone via AD and T, but not E1. These results suggest that Hsd17b12a plays a major role in E2 synthesis in sardine ovary by catalyzing the conversion of AD to T.

Comparison of structure-activity relationship for bisphenol analogs in the inhibition of gonadal 3β-hydroxysteroid dehydrogenases among human, rat, and mouse

Bisphenol A (BPA) is a widely used plastic material and its potential endocrine disrupting effect has restricted its use and increasing use of BPA alternatives has raised health concerns. However, the effect of bisphenol alternatives on steroidogenesis remains unclear. The objective of this study was to compare inhibitory potencies of 10 BPA alternatives in the inhibition of gonadal 3β-hydroxysteroid dehydrogenase (3β-HSD) in three species (human, rat and mouse). The inhibitory potency for human 3β-HSD2, rat 3β-HSD1, and mouse 3β-HSD6 ranged from bisphenol FL (IC50, 3.32 μM for human, 5.19 μM for rat, and 3.26 μM for mouse) to bisphenol E, F, and thiodiphenol (ineffective at 100 μM). Most BPA alternatives were mixed inhibitors of gonadal 3β-HSD and they dose-dependently inhibited progesterone formation in KGN cells. Molecular docking analysis showed that all BPA analogs bind to steroid and NAD+ active sites. Lipophilicity of BPA alternatives was inversely correlated with IC50 values. In conclusion, BPA alternatives mostly can inhibit gonadal 3β-HSDs and lipophilicity determines their inhibitory strength.

Abnormal Brain Protein Abundance and Cross-tissue mRNA Expression in Amyotrophic Lateral Sclerosis

Due to the limitations of the present risk genes in understanding the etiology of amyotrophic lateral sclerosis (ALS), it is necessary to find additional causative genes utilizing novel approaches. In this study, we conducted a two-stage proteome-wide association study (PWAS) using ALS genome-wide association study (GWAS) data (N = 152,268) and two distinct human brain protein quantitative trait loci (pQTL) datasets (ROSMAP N = 376 and Banner N = 152) to identify ALS risk genes and prioritized candidate genes with Mendelian randomization (MR) and Bayesian colocalization analysis. Next, we verified the aberrant expression of risk genes in multiple tissues, including lower motor neurons, skeletal muscle, and whole blood. Six ALS risk genes (SCFD1, SARM1, TMEM175, BCS1L, WIPI2, and DHRS11) were found during the PWAS discovery phase, and SARM1 and BCS1L were confirmed during the validation phase. The following MR (p = 2.10 × 10-7) and Bayesian colocalization analysis (ROSMAP PP4 = 0.999, Banner PP4 = 0.999) confirmed the causal association between SARM1 and ALS. Further differential expression analysis revealed that SARM1 was markedly downregulated in lower motor neurons (p = 7.64 × 10-3), skeletal muscle (p = 9.34 × 10-3), and whole blood (p = 1.94 × 10-3). Our findings identified some promising protein candidates for future investigation as therapeutic targets. The dysregulation of SARM1 in multiple tissues provides a new way to explain ALS pathology.

Involvement of Type 10 17β-Hydroxysteroid Dehydrogenase in the Pathogenesis of Infantile Neurodegeneration and Alzheimer's Disease

Type 10 17β-hydroxysteroid dehydrogenase (17β-HSD10) is the HSD17B10 gene product playing an appreciable role in cognitive functions. It is the main hub of exercise-upregulated mitochondrial proteins and is involved in a variety of metabolic pathways including neurosteroid metabolism to regulate allopregnanolone homeostasis. Deacetylation of 17β-HSD10 by sirtuins helps regulate its catalytic activities. 17β-HSD10 may also play a critical role in the control of mitochondrial structure, morphology and dynamics by acting as a member of the Parkin/PINK1 pathway, and by binding to cyclophilin D to open mitochondrial permeability pore. 17β-HSD10 also serves as a component of RNase P necessary for mitochondrial tRNA maturation. This dehydrogenase can bind with the Aβ peptide thereby enhancing neurotoxicity to brain cells. Even in the absence of Aβ, its quantitative and qualitative variations can result in neurodegeneration. Since elevated levels of 17β-HSD10 were found in brain cells of Alzheimer's disease (AD) patients and mouse AD models, it is considered to be a key factor in AD pathogenesis. Since data underlying Aβ-binding-alcohol dehydrogenase (ABAD) were not secured from reported experiments, ABAD appears to be a fabricated alternative term for the HSD17B10 gene product. Results of this study would encourage researchers to solve the question why elevated levels of 17β-HSD10 are present in brains of AD patients and mouse AD models. Searching specific inhibitors of 17β-HSD10 may find candidates to reduce senile neurodegeneration and open new approaches for the treatment of AD.

New insights into the substrate inhibition of human 17β-hydroxysteroid dehydrogenase type 1

Human type 1 17β-hydroxysteroid dehydrogenase (17β-HSD1),a member of the short-chain dehydrogenase/reductase family, catalyzes the last step in the bioactivation of the most potent estrogen estradiol with high specificity and is thus involved in estrogen-dependent diseases. As an oxidoreductase, 17β-HSD1 can utilize both triphosphate and diphosphate cofactors in reaction at the molecular level, but more specific with triphosphate cofactor. The NADPH is much higher than NADP+ in living cells leading to preliminary reduction action. The enzyme also showed substrate-induced inhibition unprecedented in other members of 17β-HSDs. Our previous study elucidated the structural mechanism of substrate inhibition is due to the reversely bound estrone (E1) in the substrate-binding pocket of the enzyme resulting in a dead-end complex. However, the effect of the cofactor preference on the substrate inhibition of the enzyme is not yet clear. In the present study, we solved the ternary crystal structures of 17β-HSD1 in complex with E1 and cofactor analog NAD+ . Combined with molecular dynamics simulation using the enzyme with NADH/NADPH and different oriented E1 (normally oriented, E1N; reversely oriented, E1R), such ternary structure provides a complete picture of enzyme-substrate-cofactor interactions. The results reveal that different cofactors and substrate binding mode affect the allosteric effect between the two subunits of the enzyme. And the results from MD simulations confirmed that His²²¹ plays a key role in the formation of dead-end complex in NADPH complex, and the absence of stable interaction between His²²¹ and E1R in the NADH complex should be the main reason for its lack of substrate inhibition.

Hydroxysteroid 17β-dehydrogenase 11 accumulation on lipid droplets promotes ethanol-induced cellular steatosis

Lipid droplets (LDs) are fat-storing organelles enclosed by a phospholipid monolayer, which harbors membrane-associated proteins that regulate distinct LD functions. LD proteins are degraded by the ubiquitin-proteasome system (UPS) and/or by lysosomes. Because chronic ethanol (EtOH) consumption diminishes the hepatic functions of the UPS and lysosomes, we hypothesized that continuous EtOH consumption slows the breakdown of lipogenic LD proteins targeted for degradation, thereby causing LD accumulation. Here, we report that LDs from livers of EtOH-fed rats exhibited higher levels of polyubiquitylated-proteins, linked at either lysine 48 (directed to proteasome) or lysine 63 (directed to lysosomes) than LDs from pair-fed control rats. MS proteomics of LD proteins, immunoprecipitated with UB remnant motif antibody (K-ε-GG), identified 75 potential UB proteins, of which 20 were altered by chronic EtOH administration. Among these, hydroxysteroid 17β-dehydrogenase 11 (HSD17β11) was prominent. Immunoblot analyses of LD fractions revealed that EtOH administration enriched HSD17β11 localization to LDs. When we overexpressed HSD17β11 in EtOH-metabolizing VA-13 cells, the steroid dehydrogenase 11 became principally localized to LDs, resulting in elevated cellular triglycerides (TGs). Ethanol exposure augmented cellular TG, while HSD17β11 siRNA decreased both control and EtOH-induced TG accumulation. Remarkably, HSD17β11 overexpression lowered the LD localization of adipose triglyceride lipase. EtOH exposure further reduced this localization. Reactivation of proteasome activity in VA-13 cells blocked the EtOH-induced rises in both HSD17β11 and TGs. Our findings indicate that EtOH exposure blocks HSD17β11 degradation by inhibiting the UPS, thereby stabilizing HSD17β11 on LD membranes, to prevent lipolysis by adipose triglyceride lipase and promote cellular LD accumulation.

Molecular mechanisms underlying the defects of two novel mutations in the HSD17B3 gene found in the Tunisian population

17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) converts Δ4-androstene-3,17-dione (androstenedione) to testosterone. It is expressed almost exclusively in the testes and is essential for appropriate male sexual development. More than 70 mutations in the HSD17B3 gene that cause 17β-HSD3 deficiency and result in 46,XY Disorders of Sex Development (46,XY DSD) have been reported. This study describes three novel Tunisian cases with mutations in HSD17B3. The first patient is homozygous for the previously reported mutation p.C206X. The inheritance of this mutation seemed to be independent of consanguineous marriage, which can be explained by its high frequency in the Tunisian population. The second patient has a novel splice site mutation in intron 6 at position c.490 -6 T > C. A splicing assay revealed a complete omission of exon 7 in the resulting HSD17B3 mRNA transcript. Skipping of exon 7 in HSD17B3 is predicted to cause a frame shift in exon 8 that affects the catalytic site and results in a truncation in exon 9, leading to an inactive enzyme. The third patient is homozygous for the novel missense mutation p.K202M, representing the first mutation identified in the catalytic tetrad of 17β-HSD3. Site-directed mutagenesis and enzyme activity measurements revealed a completely abolished 17β-HSD3 activity of the p.K202M mutant, despite unaffected protein expression, compared to the wild-type enzyme. Furthermore, the present study emphasizes the importance of genetic counselling, detabooization of 46,XY DSD, and a sensitization of the Tunisian population for the risks of consanguineous marriage.

Molecular docking, 3D-QSAR and simulation studies for identifying pharmacophoric features of indole derivatives as 17β-hydroxysteroid dehydrogenase type 5 (17β-HSD5) inhibitors

Excess of androgens leads to various diseases such as Poly-Cystic Ovarian Syndrome, Prostate Cancer, Hirsutism, Obesity and Acne. 17β-Hydroxysteroid Dehydrogenase type 5 (17β-HSD5) converts androstenedione into testosterone peripherally, thereby significantly contributing to the development of these diseases. Indole-bearing scaffolds are reported as potential 17β-HSD5 inhibitors for the manifestation of diseases arising due to androgen excess. In the present work, we have extensively performed a combination of molecular docking, Gaussian field-based 3D-QSAR, Pharmacophore mapping and MD-simulation studies (100 ns) to identify the pharmacophoric features of indole-based compounds as potent 17β-HSD5 inhibitors. Molecular simulation studies of the most potent compound in the binding pocket of enzyme revealed that the compound 11 was stable in the binding pocket and showed good binding affinity through interactions with various residues of active site pocket. The Molecular mechanics Generalized Born surface area continuum solvation (MM/GBSA) and Molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) calculations revealed that the compound 11 possessed a free binding energy of -36.36 kcal/mol and -7.00 kcal/mol, respectively, which was better as compared to reference compound Desmethyl indomethacin (DES). The developed pharmacophore will be helpful to design novel indole-based molecules as potent 17β-HSD5 inhibitors for the treatment of various androgenic disorders.Communicated by Ramaswamy H. Sarma.

New Insights into Testosterone Biosynthesis: Novel Observations from HSD17B3 Deficient Mice

Androgens such as testosterone and dihydrotestosterone (DHT) are essential for male sexual development, masculinisation, and fertility. Testosterone is produced via the canonical androgen production pathway and is essential for normal masculinisation and testis function. Disruption to androgen production can result in disorders of sexual development (DSD). In the canonical pathway, 17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) is viewed as a critical enzyme in the production of testosterone, performing the final conversion required. HSD17B3 deficiency in humans is associated with DSD due to low testosterone concentration during development. Individuals with HSD17B3 mutations have poorly masculinised external genitalia that can appear as ambiguous or female, whilst having internal Wolffian structures and testes. Recent studies in mice deficient in HSD17B3 have made the surprising finding that testosterone production is maintained, male mice are masculinised and remain fertile, suggesting differences between mice and human testosterone production exist. We discuss the phenotypic differences observed and the possible other pathways and enzymes that could be contributing to testosterone production and male development. The identification of alternative testosterone synthesising enzymes could inform the development of novel therapies to endogenously regulate testosterone production in individuals with testosterone deficiency.

Mechanism of 17β-estradiol degradation by Rhodococcus equi via the 4,5-seco pathway and its key genes

Steroid estrogens have been detected in oceans, rivers, lakes, groundwaters, soils, and even urban water supply systems, thereby inevitably imposing serious impacts on human health and ecological safety. Indeed, many estrogen-degrading bacterial strains and degradation pathways have been reported, with the 4,5-seco pathway being particularly important. However, few studies have evaluated the use of the 4,5-seco pathway by actinomycetes to degrade 17β-estradiol (E2). In this study, 5 genes involved in E2 degradation were identified in the Rhodococcus equi DSSKP-R-001 (R-001) genome and then heterologously expressed to confirm their functions. The transformation of E2 with hsd17b14 reached 63.7% within 30 h, resulting in transformation into estrone (E1). Furthermore, we found that At1g12200-encoded flavin-binding monooxygenase (FMO_At1g12200) can transform E1 at a rate of 51.6% within 30 h and can transform E1 into 4-hydroxyestrone (4-OH E1). In addition, catA and hsaC genes were identified to further transform 4-OH E1 at a rate of 97-99%, and this reaction was accomplished by C-C cleavage at the C4 position of the A ring of 4-OH E1. This study represents the first report on the roles of these genes in estrogen degradation and provides new insights into the mechanisms of microbial estrogen metabolism and a better understanding of E2 degradation via the 4,5-seco pathway by actinomycetes.

Association of genetic polymorphisms with local steroid metabolism in human benign breasts

PURPOSE

Although alterations of concentrations in circulating steroids have been linked to single nucleotide polymorphisms (SNPs) of steroidogenic enzymes, we hypothesized that SNPs of such enzymes located within the breast affect local steroid concentrations more than products of such SNPs absorbed from the circulation.

METHODS

Steroids (estradiol, estrone, testosterone, androstenedione, DHEA, DHEA sulfate, progesterone) in nipple aspirate fluid (NAF) were purified by HPLC and they along with serum steroids were quantified by immunoassays. Polymorphisms of the transporter SLCO2B1 and enzymes HSD3B1, CYP19A1, HSD17B12, AKR1C3, CYP1B1, and SRD5A1 were measured in white blood cell DNA.

RESULTS

Steroid concentrations in NAF of subjects with homozygous minor genotypes differed from those with heterozygotes, i.e., SLCO2B1 (rs2851069) decreased DHEAS (p = 0.04), HSD17B12 (rs11555762) increased estradiol (p < 0.004), and CYP1B1 (rs1056836) decreased estradiol (p = 0.017) and increased progesterone (p = 0.05). Also, in serum, CYP19A1 (rs10046 and rs700518) both decreased testosterone (p = 0.02) and SRD5A1 increased androstenedione (p = 0.006). Steroids in subjects with major homozygotes did not differ from those with heterozygotes indicating recessive characteristics.

CONCLUSIONS

In the breast, SNPs were associated with decreased uptake of DHEAS (SLCO2B1), increased estradiol concentrations through increased oxidoreductase activity (HSD17B12), or decreased estradiol concentrations by presumed formation of 4-hydroxyestradiol (CYP1B1). CYP19A1 was associated with decreased testosterone concentrations in serum but had no significant effect on estrogen or androgen concentrations within the breast. The hormone differences observed in NAF were not usually evident in serum, indicating the importance of assessing the effect of these SNPs within the breast.

The multi-specific human 17 beta-hydroxysteroid dehydrogenase type 7: Non-competitive inhibitors can target different catalyses to facilitate breast cancer treatment

Human 17β-hydroxysteroid dehydrogenase type 7 (17β-HSD7), a special multifunctional enzyme, activates the estrogen estrone while inactivating the potent androgen dihydrotestosterone. Thus, this enzyme has become an ideal target for hormone-dependent breast cancer treatment, as its inhibition leads to estradiol reduction and dihydrotestosterone restoration. However, a particular concern has arisen related to an additional role in cholesterol biosynthesis, as inhibition of the enzyme may lead to undesirable side effects. Our findings demonstrate that the available enzyme inhibitors are non-competitive. Among these, many such as INH81, are specific toward sex-hormone conversion, whereas others represented by 4-bromo-ethynylestradiol, are more specific for zymosterone reduction occurring during cholesterol biosynthesis. The binding of non-competitive inhibitors does not affect the substrate binding on the enzyme. This is the first demonstration of non-competitive inhibitors acting selectively on different catalyses, thereby facilitating inhibitor uses for breast cancer treatment. We aim to quickly communicate the novel results.

Gonadal sex steroid hormone secretion after exposure of male rats to estrogenic chemicals and their combinations

Environmental chemicals can interfere with the endocrine axis hence they are classified as endocrine disrupting chemicals (EDCs). Bisphenol S (BPS) is used in the manufacture of consumer products because of its superior thermal stability and is thought to be a safe replacement chemical for its analog bisphenol A (BPA). However, the safety profile of these compounds alone or in the presence of other EDCs is yet to be fully investigated. Also, the estrogenic chemical 17α-ethinyl estradiol (EE2) and a constituent of female oral contraceptives for women, is present in water supplies. To simulate concurrent exposure of the population to chemical mixtures, we investigated the effects of BPA, BPS, EE2, and their combinations on sex steroid secretion in the growing male rat gonad. Prepubertal and pubertal male rats at 21 and 35 days of age were provided test chemicals in drinking water (parts per billion) for 14 days. At termination of exposure, some individual chemical effects were modified by exposure to chemical combinations. Single chemical exposures markedly decreased androgen secretion but their combination (e.g., BPA + BPS + EE2) caused the opposite effect, i.e., increased Leydig cell T secretion. Also, the test chemicals acting alone or in combination increased testicular and Leydig cell 17β-estradiol (E2) secretion. Chemical-induced changes in T and E2 secretion were associated with altered testicular expression of the cholesterol side-chain cleavage (Cyp11a1) and 17β-hydroxysteroid dehydrogenase (Hsd17β) enzyme protein. Additional studies are warranted to understand the mechanisms by which single and chemical combinations impact function of testicular cells and disrupt their paracrine regulation.

16-Picolyl-androsterone derivative exhibits potent 17β-HSD3 inhibitory activity, improved metabolic stability and cytotoxic effect on various cancer cells: Synthesis, homology modeling and docking studies

A new androsterone derivative bearing a 16β-picolyl group (compound 5; FCO-586-119) was synthetized in four steps from the lead compound 1 (RM-532-105). We measured its inhibitory activity on 17β-HSD3 using microsomal fraction of rat testes as well as transfected LNCaP[17β-HSD3] cells. We then assessed its metabolic stability as well as its cytotoxic effect against a panel of cancer cell lines. The addition of a picolyl moiety at C-16 of RM-532-105 steroid core improves the 17β-HSD3 inhibitory activity in the microsomal fraction of rat testes, but not in whole LNCaP[17β-HSD3] cells. Interestingly, this structural modification enhances 3-fold the metabolic stability in conjunction with a significant cytotoxic effect against pancreatic, ovarian, breast, lung, and prostate cancer cells. Because the inhibitory activity data against 17β-HSD3 suggested that both steroid derivatives are non-competitive inhibitors, we performed docking and molecular dynamics simulations using a homology model of this membrane-associated enzyme. The results of these simulations revealed that both RM-532-105 (1) and FCO-586-119 (5) can compete for the cofactor-binding site displaying better binding energy than NADP+.

Adipose tissue estrogen production and metabolism in premenopausal women

OBJECTIVE

Although the ovaries produce the majority of estrogens in women before menopause, estrogen is also synthesized in peripheral tissues such as adipose tissue (AT). The typical female AT distribution, concentrated in subcutaneous and femoro-gluteal regions, is estrogen-mediated, but the significance of estrogen synthesis in AT of premenopausal women is poorly understood.

DESIGN AND METHODS

Serum and subcutaneous and visceral AT homogenates from 28 premenopausal women undergoing non-malignant surgery were analyzed for estrone, estradiol, and serum estrone sulfate (E₁S) concentrations with liquid chromatography-tandem mass spectrometry. Isotopic precursors were used to measure enzyme activities of estrone-producing steroid sulfatase and estradiol-producing 17β-hydroxysteroid dehydrogenases (17β-HSD). Messenger RNA (mRNA) expression levels of genes for estrogen-metabolizing enzymes were analyzed using real-time reverse transcription quantitative polymerase chain reaction.

RESULTS

While estradiol was the predominant circulating active estrogen, estrone dominated in AT, with a higher concentration in visceral than subcutaneous AT (median, 2657 vs 1459 pmol/kg; P = 0.002). Both AT depots converted circulating E₁S to estrone, and estrone to estradiol. Median levels of estrone were five to ten times higher in subcutaneous and visceral AT than in serum (P < 0.001) and the estradiol level in visceral AT was 1.3 times higher than in serum (P < 0.005). The local estrone concentration in visceral AT correlated positively with mRNA expression of estrone-producing enzyme aromatase (r = 0.65, P = 0.003). Waist circumference correlated positively with increased estradiol production in subcutaneous AT (r = 0.60, P = 0.039).

CONCLUSIONS

Premenopausal AT demonstrated high estrogenic enzyme activity and considerable local estrogen concentrations. This may be a factor promoting female-typical AT distribution in premenopausal women.

Prenatal exposure to hexavalent chromium disrupts testicular steroidogenic pathway in peripubertal F1 rats

We have reported sub-fertility in F1 progeny rats with gestational exposure to hexavalent chromium [Cr(VI)], which had disrupted Sertoli cell (SC) structure and function, and decreased testosterone (T). However, the underlying mechanism for reduced T remains to be understood. We tested the hypothesis "transient prenatal exposure to Cr(VI) affects testicular steroidogenesis by altering hormone receptors and steroidogenic enzyme proteins in Leydig cells (LCs)." Pregnant Wistar rats were given drinking water containing 50, 100, and 200 mg/L potassium dichromate during gestational days 9-14, encompassing fetal differentiation window of the testis from the bipotential gonad. F1 male rats were euthanized on postnatal day 60 (peripubertal rats with adult-type LCs alone). Results showed that prenatal exposure to Cr(VI): (i) increased accumulation of Cr(III) in the testis of F1 rats; (ii) increased serum levels of luteinizing and follicle stimulating hormones (LH and FSH), and 17β estradiol, and decreased prolactin and T; (iii) decreased steroidogenic acute regulatory protein, cytochrome P450 11A1, cytochrome P450 17A1, 3β- and 17β-hydroxysteroid dehydrogenases, cytochrome P450 aromatase and 5α reductase proteins, (iv) decreased specific activities of 3β and 17β hydroxysteroid dehydrogenases; (v) decreased receptors of LH, androgen and estrogen in LCs; (vi) decreased 5α reductase and receptor proteins of FSH, androgen, and estrogen in SCs. The current study concludes that prenatal exposure to Cr(VI) disrupts testicular steroidogenesis in F1 progeny by repressing hormone receptors and key proteins of the steroidogenic pathway in LCs and SCs.

Upregulation of Cyp19a1 and PPAR-γ in ovarian steroidogenic pathway by Ficus religiosa: A potential cure for polycystic ovary syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Quite a few plants are in use to treat female infertility and associated problems. Availing the cues from traditional knowledge, phytochemical studies and ethnopharmacological evidences, the aphrodisiac plant Ficus religiosa (F. religiosa) is widely in use to cure infertility in women. For instance, the juice of leaf and aerial root of F. religiosa is reported to normalize the dysregulated menstrual cycle in women. Besides, it is believed that regular circumambulation of F. religiosa during the early hours of the morning helps women in alleviating infertility which could be attributed to the potential phytovolatiles released from F. religiosa. However, the evidences for therapeutic potential of F. religiosa in treating female infertility are arbitrary and mostly anecdotal.

AIM OF THE STUDY

The present study was aimed at examining if extracts of fresh and/or dry leaf of F. religiosa would cure polycystic ovary syndrome (PCOS) in the rat model.

METHODS

Rats were divided into seven groups; control (Group I), PCOS-induced (P.O, Letrozole -1 mg/kg BW for 21 days) and untreated (Group II), PCOS-induced and treated with the leaf extracts of F. religiosa (Groups III-VI), and, PCOS-induced and treated with pioglitazone (Group VII). The estrous intervals, body and organ weights (ovary and uterus), and serum hormones (testosterone, luteinizing hormone [LH], estrogen, and progesterone) were measured, and the expression of Cyp19a1 (aromatase), and Peroxisome Proliferator-Activated Receptor-γ (PPAR-γ) were assessed in the experimental rats. The levels of 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD), and antioxidants (MDA, GSH, GPx, SOD, and CAT) were also quantified. Besides, the putative volatile compounds in the esterified leaf extracts were identified using Gas Chromatography-Mass Spectrometry (GC-MS).

RESULTS

Letrozole treatment induced irregular estrous and altered weight of organs and hormonal milieu, which were reverted to normal in leaf extracts-treated PCOS-induced rats. Remarkably, fresh leaf treatment up-regulated Cyp19a1and PPAR-γ and increased the levels of 3β-HSD and 17β-HSD. We found 3-acetoxy-3-hydroxy-propionic acid in fresh and dry leaf extracts, which we attribute to efficacy of the extracts in alleviating PCOS.

CONCLUSION

Put together, our findings suggest the leaves of F. religiosa as potential in alleviating PCOS, mainly due to the presence of putative volatile molecules. Further screening of the leaves of F. religiosa is recommended to identify other key molecules and to develop a systematic therapeutic intervention for PCOS.

Premature Adrenarche in Girls Characterized By Enhanced 17,20-Lyase and 17β-Hydroxysteroid Dehydrogenase Activities

CONTEXT

Girls with premature adrenarche (PA) may have a higher risk of developing polycystic ovary syndrome (PCOS) and metabolic syndrome. The biological purpose of adrenarche is unknown and the role of novel biosynthetic pathways remains unclear.

OBJECTIVE

To compare the urinary steroid metabolome and enzyme activities of girls with PA to age-matched control girls and to published steroid values of girls with normal adrenarche and of women with PCOS and their newborn daughters.

DESIGN

Prospective observational study from 2009 to 2014.

SETTING

Academic pediatric endocrinology referral center.

PARTICIPANTS

Twenty-three girls with PA and 22 healthy, age-matched girls.

MAIN OUTCOME MEASURES

Steroid metabolites in 24-hour urine samples, including 4 progesterones, 5 corticosterones, aldosterone, 13 androgens, 2 estrogens, 14 glucocorticoids, and enzyme activities represented by metabolite ratios.

RESULTS

Girls with PA had a higher body mass index (mean standard deviation scores 0.9 vs -0.3, P = 0.013). Androgen excretion was higher in PA girls than in control girls (median 3257 nmol/24 hours vs 1627 nmol/24 hours, P < 0.001), in particular metabolites from alternate androgen pathways. The amount of progesterone, corticosterone, aldosterone, estrogen, and cortisol metabolites were similar between groups. Activities of 17β-hydroxysteroid-dehydrogenase and of 17,20-lyase were higher in girls with PA. Activities of 3β-hydroxysteroid-dehydrogenase, 21-hydroxylase, and 5α-reductase activity were not different between groups, in contrast to published results on girls with normal adrenarche or PCOS females.

CONCLUSIONS

Metabolites and enzymes involved in alternate androgen pathways appear to be markers of PA. Prospective studies should assess whether steroid production in PA also differs from adrenarche at normal timing and persists into adulthood.

Identification of Functional Single Nucleotide Polymorphisms in Porcine HSD17B14 Gene Associated with Estrus Behavior Difference between Large White and Mi Gilts

Steroid hormone levels are associated with estrous behavior, which affects timely mating and reproductive efficiency in pigs. 17β-hydroxysteroid dehydrogenase type 14 (HSD17B14) modulates steroid synthesis and metabolism. To identify the functional single nucleotide polymorphisms (SNPs) in the porcine HSD17B14 gene, ear tissues from Large White and Mi gilts were collected to extract genomic DNA. Variable lengths of truncated promoter of HSD17B14 gene were used to determine the promoter activity by a dual luciferase reporter system. The vector HSD17B14^Phe or HSD17B14^Val was transfected into porcine granulosa cells (GCs). The core promoter region was identified between -72bp and -218bp. Six of seven SNPs had significant differences of allele frequency between Large White and Mi gilts. The plasmids with the wild genotype AA of rs329427898 maintained a smaller fraction of promoter activity compared with the plasmids with the mutant genotype GG, while the plasmids with wild the genotype TT of rs319864566 had a greater promoter activity than the plasmids with the mutant genotype CC. A missense mutation (Phe73Val) caused changes in the structural dynamics and function of the HSD17B14 protein. The highly expressed HSD17B14^Val degraded less estradiol into estrone, while the relatively lowly expressed HSD17B14^Phe degraded more estradiol into estrone, suggesting the protein activity of HSD17B14^Phe was greater than that of HSD17B14^Val. Moreover, the HSD17B14^Phe group has a greater apoptosis rate of porcine GCs. The HSD17B14 gene could been used as a candidate molecular marker for estrus behavior in pigs.

Inhibitory effect of central ghrelin on steroid synthesis affecting reproductive health in female mice

Ghrelin is a 28-amino acid peptide hormone that regulates ovarian steroid hormone synthesis; however, there is limited evidence regarding the regulation of this pathway by ghrelin in mice ovary. Thus, we aimed to investigate whether central ghrelin action plays a role in murine reproductive health by inhibiting steroid synthesis. Further, we sought to examine the mechanism of central ghrelin action in ovarian steroid hormone synthesis. After the administration of intracerebroventricular ghrelin (1 nmol), we found reduced serum concentrations of oestradiol and progesterone and reduced secretion of follicle-stimulating hormone and luteinising hormone. Although ghrelin reduced 3β-hydroxysteroid dehydrogenase mRNA and protein levels in the hypothalamus, it did not affect the expression of steroidogenic acute regulatory protein and cytochrome P450 17A1. In the ovary, central ghrelin regulation indirectly inhibited the mRNA and protein levels of steroidogenic acute regulatory protein, cytochrome P450 17A1, and 3β-hydroxysteroid dehydrogenase. Moreover, no changes were observed in the expression of proliferating cell nuclear antigen and phosphorylation of extracellular signal-regulated kinase. We hypothesised that central ghrelin regulation suppressed serum oestradiol and progesterone levels by indirectly inhibiting the expression of steroidogenic acute regulatory protein, cytochrome P450 17A1, and 3β-hydroxysteroid dehydrogenase in the ovary. In this regulation, the suppressed secretion of the follicle-stimulating hormone and luteinising hormone in the pituitary by ghrelin could be involved. Furthermore, hypothalamic 3β-hydroxysteroid dehydrogenase expression is reduced by ghrelin injection.

Inhibition of visfatin/NAMPT affects ovarian proliferation, apoptosis, and steroidogenesis in pre-pubertal mice ovary

Pubertal ovarian function might be dependent on the factors present in the pre-pubertal stages. Visfatin regulates ovarian steroidogenesis in adult. To date, no study has investigated the role of visfatin either in pre-pubertal or pubertal mice ovary. Thus, we investigated the role of visfatin in pre-pubertal mice ovary in relation to steroidogenesis and proliferation and apoptosis in vitro by inhibiting the endogenous visfatin by a specific inhibitor, FK866. Inhibition of visfatin increased the estrogen secretion and also up-regulated the expression of CYP11A1, 17βHSD and CYP19A1 in mice ovary. Furthermore, active caspase3 was up-regulated along with the down-regulation of BAX and BCL2 in the pre-pubertal ovary after visfatin inhibition. The expression of GCNA, PCNA, and BrdU labeling was also decreased by FK866 treatment. These results suggest that visfatin inhibits steroidogenesis, increases proliferation, and suppresses apoptosis in the pre-pubertal mice ovary. So, visfatin is a new regulator of ovary function in pre-pubertal mice.

Changes in Adrenal Androgens and Steroidogenic Enzyme Activities From Ages 2, 4, to 6 Years: A Prospective Cohort Study

CONTEXT

The levels of adrenal androgens are increased through the action of steroidogenic enzymes with morphological changes in the adrenal zona reticularis.

OBJECTIVE

We investigated longitudinal changes in androgen levels and steroidogenic enzyme activities during early childhood.

DESIGN AND PARTICIPANTS

From a prospective children's cohort, the Environment and Development of Children cohort, 114 boys and 86 girls with available blood samples from ages 2, 4, and 6 years were included.

OUTCOME MEASUREMENTS

Serum concentrations of adrenal androgens using liquid chromatography-tandem mass spectrometry and steroidogenic enzyme activity calculated by the precursor/product ratio.

RESULTS

During ages 2 to 4 years, 17,20-lyase and dehydroepiandrosterone (DHEA) sulfotransferase activities increased (P < 0.01 for both in boys). During ages 4 to 6 years, 17,20-lyase activity persistently increased, but 3β-hydroxysteroid dehydrogenase (HSD) and 17β-HSD activities decreased (P < 0.01 for all). Serum DHEA sulfate (DHEA-S) levels persistently increased from 2, 4, to 6 years, and DHEA, 17-hydroxyprogesterone, and androstenedione levels increased during ages 4 to 6 years (P < 0.01 for all). Serum DHEA-S levels during early childhood were associated with body mass index z-scores (P = 0.001 in only boys).

CONCLUSION

This study supports in vivo human evidence of increased 17,20-lyase and DHEA sulfotransferase activities and decreased 3β-HSD activity during early childhood.

Conversion of Estrone to 17β-Estradiol: A Potential Confounding Factor in Assessing Risks of Environmental Estrogens to Fish

Feminization of male fish and the role of endocrine-active chemicals in this phenomenon has been an area of intense study for many years. Estrone (E1), a natural steroid, is found in aquatic environments sometimes at high concentrations relative to the estrogenic steroids 17β-estradiol (E2) and 17α-ethynylestradiol. However, E1 has been less thoroughly studied than E2 or 17α-ethynylestradiol due in part to a relatively lower potency in metabolically limited estrogen receptor (ER) binding/activation assays. Recent evidence suggests that in vivo biotransformation of E1 to E2 may occur in fathead minnows (Pimephales promelas) residing in environments with high concentrations of E1, such as near wastewater treatment plants. The enzymes likely responsible for this biotransformation, 17β-hydroxysteroid dehydrogenases (17βHSDs), have been well characterized in mammals but to a lesser extent in fish species. In the present study, a novel systematic analysis of amino acid sequence data from the National Center for Biotechnology Information database demonstrated that multiple 17βHSD isoforms are conserved across different fish species. Experimentally, we showed that metabolically active hepatic cytosolic preparations from 2 commercially important salmonid species, rainbow trout and lake trout, biotransformed E1 to E2 to a degree sufficient to alter results of competitive ER binding assays. These results from in silico and in vitro analyses indicate that E1 and biotransformation may play a significant role in adverse effects on development and reproduction of a variety of fish species in contaminated aquatic environments. Environ Toxicol Chem 2020;39:2028-2040. Published 2020. This article is a US Government work and is in the public domain in the USA.

Study of Biomolecular Interactions of Mitochondrial Proteins Related to Alzheimer's Disease: Toward Multi-Interaction Biomolecular Processes

Progressive mitochondrial dysfunction due to the accumulation of amyloid beta (Aβ) peptide within the mitochondrial matrix represents one of the key characteristics of Alzheimer's disease (AD) and appears already in its early stages. Inside the mitochondria, Aβ interacts with a number of biomolecules, including cyclophilin D (cypD) and 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10), and affects their physiological functions. However, despite intensive ongoing research, the exact mechanisms through which Aβ impairs mitochondrial functions remain to be explained. In this work, we studied the interactions of Aβ with cypD and 17β-HSD10 in vitro using the surface plasmon resonance (SPR) method and determined the kinetic parameters (association and dissociation rates) of these interactions. This is the first work which determines all these parameters under the same conditions, thus, enabling direct comparison of relative affinities of Aβ to its mitochondrial binding partners. Moreover, we used the determined characteristics of the individual interactions to simulate the concurrent interactions of Aβ with cypD and 17β-HSD10 in different model situations associated with the progression of AD. This study not only advances the understanding of Aβ-induced processes in mitochondria during AD, but it also provides a new perspective on research into complex multi-interaction biomolecular processes in general.

Impaired Hepatic Vitamin A Metabolism in NAFLD Mice Leading to Vitamin A Accumulation in Hepatocytes

BACKGROUND & AIMS

Systemic retinol (vitamin A) homeostasis is controlled by the liver, involving close collaboration between hepatocytes and hepatic stellate cells (HSCs). Genetic variants in retinol metabolism (PNPLA3 and HSD17B13) are associated with non-alcoholic fatty liver disease (NAFLD) and disease progression. Still, little mechanistic details are known about hepatic vitamin A metabolism in NAFLD, which may affect carbohydrate and lipid metabolism, inflammation, oxidative stress and the development of fibrosis and cancer, e.g. all risk factors of NAFLD.

METHODS

Here, we analyzed vitamin A metabolism in 2 mouse models of NAFLD; mice fed a high-fat, high-cholesterol (HFC) diet and Leptinob mutant (ob/ob) mice.

RESULTS

Hepatic retinol and retinol binding protein 4 (RBP4) levels were significantly reduced in both mouse models of NAFLD. In contrast, hepatic retinyl palmitate levels (the vitamin A storage form) were significantly elevated in these mice. Transcriptome analysis revealed a hyperdynamic state of hepatic vitamin A metabolism, with enhanced retinol storage and metabolism (upregulated Lrat, Dgat1, Pnpla3, Raldh's and RAR/RXR-target genes) in fatty livers, in conjunction with induced hepatic inflammation (upregulated Cd68, Tnfα, Nos2, Il1β, Il-6) and fibrosis (upregulated Col1a1, Acta2, Tgfβ, Timp1). Autofluorescence analyses revealed prominent vitamin A accumulation in hepatocytes rather than HSC in HFC-fed mice. Palmitic acid exposure increased Lrat mRNA levels in primary rat hepatocytes and promoted retinyl palmitate accumulation when co-treated with retinol, which was not detected for similarly-treated primary rat HSCs.

CONCLUSION

NAFLD leads to cell type-specific rearrangements in retinol metabolism leading to vitamin A accumulation in hepatocytes. This may promote disease progression and/or affect therapeutic approaches targeting nuclear receptors.

Human dehydrogenase/reductase SDR family member 11 (DHRS11) and aldo-keto reductase 1C isoforms in comparison: Substrate and reaction specificity in the reduction of 11-keto-C19-steroids

Recent studies have shown that an adrenal steroid 11β-hydroxy-4-androstene-3,17-dione serves as the precursor to androgens, 11-ketotestosterone and 11-ketodihydrotestosterone (11KDHT). The biosynthetic pathways include the reduction of 3- and 17-keto groups of the androgen precursors 11-keto-C₁₉-steroids, which has been reported to be mediated by three human enzymes; aldo-keto reductase (AKR)1C2, AKR1C3 and 17β-hydroxysteroid dehydrogenase (HSD) type-3. To explore the contribution of the enzymes in the reductive metabolism, we kinetically compared the substrate specificity for 11-keto-C₁₉-steroids among purified recombinant preparations of four AKRs (1C1, 1C2,1C3 and 1C4) and DHRS11, which shows 17β-HSD activity. Although AKR1C1 did not reduce the 11-keto-C₁₉-steroids, AKR1C3 and DHRS11 reduced 17-keto groups of 11-keto-4-androstene-3,17-dione, 11-keto-5α-androstane-3,17-dione (11K-Adione) and 11-ketoandrosterone with K_m values of 5-28 μM. The 3-keto groups of 11KDHT and 11K-Adione were reduced by AKR1C4 (K_m 1 μM) more efficiently than by AKR1C2 (K_m 5 and 8 μM, respectively). GC/MS analysis of the products showed that DHRS11 acts as 17β-HSD, and that AKR1C2 and AKR1C4 are predominantly 3α-HSDs, but formed a minor 3β-metabolite from 11KDHT. Since DHRS11 was thus newly identified as 11-keto-C₁₉-steroid reductase, we also investigated its substrate-binding mode by molecular docking and site-directed mutagenesis of Thr163 and Val200, and found the following structural features: 1). There is a space that accommodates the 11-keto group of the 11-keto-C₁₉-steroids in the substrate-binding site. 2) Val200 is a critical determinant for exhibiting the strict 17β-HSD activity of the enzyme, because the Val200Leu mutation resulted in both significant impairment of the 17β-HSD activity and emergence of 3β-HSD activity towards 5α-androstanes including 11KDHT.

17β-Hydroxysteroid dehydrogenase type 12 is responsible for maturation-inducing steroid synthesis during oocyte maturation in Nile tilapia

17α, 20β-Dihydroxy-4-pregnen-3-one (DHP) is a maturation-inducing steroid in many teleost fish. Carbonyl reductase-like 20β-hydroxysteroid dehydrogenase (CR/20β-HSD) is a candidate enzyme responsible for DHP production during oocyte maturation in various fish, including Nile tilapia. However, a novel type of 17β-hydroxysteroid dehydrogenase, type 12-like (17β-HSD12L), is responsible for DHP production during oocyte maturation in masu salmon. 17β-HSD12 (presumably orthologous to salmon 17β-HSD12L) has been detected in Nile tilapia; however, its enzymatic activity and specific ability to convert the DHP substrate 17α-hydroxyprogesterone (17OHP) have not been examined. This study aimed to determine whether CR/20β-HSD or 17β-HSD12 is responsible for DHP production during oocyte maturation in the Nile tilapia. Mammalian expression vectors containing tilapia hsd17b12 or CR/20bhsd were transfected into HEK293T cells, followed by incubation with 17OHP. HEK293T cells transfected with hsd17b12 exhibited a strong ability to convert exogenous 17OHP to DHP (73.8% yield). Cells transfected with CR/20bhsd or the control vector converted only 7.4% and 7.5% of 17OHP to DHP, respectively. In addition, based on LC-MS/MS analyses, 17β-HSD12 did not convert any substrates other than 17OHP, including DHP, adrenosterone, androstenedione, estrone, testosterone, 11-ketotestosterone, and estradiol-17β. CR/20β-HSD showed strong 17β-HSD oxidoreductase activity especially with adrenosterone and androstenedione. Tissue-specific hsd17b12 expression analyzed by RT-PCR showed that hsd17b12 mRNA was strongest amplification in full-grown follicles. Finally, full-grown ovarian follicles were incubated with salmon pituitary extract (SPE, 100 µg/mL) or human chorionic gonadotropin (HCG, 100 IU/mL) to induce 20β-HSD activity in vitro, and enzyme activity was assessed by co-incubation with 100 ng/mL 17OHP for 2, 4, 8, and 16 h. Conversion of 17OHP to DHP by ovarian follicles incubated with SPE and HCG peaked at 16 h, subsequent with increased follicular hsd17b12 mRNA levels, which were significantly higher than those in control incubations. However, the levels of CR/20bhsd mRNA remained low and did not differ among time points. The present study strongly suggests that 17β-HSD12, and not CR/20β-HSD, is the 20β-HSD responsible for DHP production by ovarian follicles during oocyte maturation in Nile tilapia.

The Footprints of Oxidative Stress and Mitochondrial Impairment in Arsenic Trioxide-Induced Testosterone Release Suppression in Pubertal and Mature F1-Male Balb/c Mice via the Downregulation of 3β-HSD, 17β-HSD, and CYP11a Expression

Exposure to arsenic (AS) causes abnormalities in the reproductive system; however, the precise cellular pathway of AS toxicity on steroidogenesis in developing F1-male mice has not been clearly defined. In this study, paternal mice were treated with arsenic trioxide (As₂O₃; 0, 0.2, 2, and 20 ppm in drinking water) from 5 weeks before mating until weaning and continued for male offspring from weaning until maturity (in vivo). Additionally, Leydig cells (LCs) were isolated from the testes of sacrificed F1-intact mature male mice and incubated with As₂O₃ (0, 1, 10, and 100 μM) for 48 h (in vitro). Biomarkers of mitochondrial impairment, oxidative stress, and several steroidogenic genes, including the steroidogenic acute regulatory (StAR) protein, cytochrome P450 side-chain cleaving enzyme (P450scc; Cyp11a), 3β-hydroxysteroid dehydrogenase (3β-HSD), and 17β-hydroxysteroid dehydrogenase (17β-HSD), were evaluated. High doses of As₂O₃ interrupted testosterone (T) biosynthesis and T-related gene expression in these experimental models. Altogether, overconsumption of As₂O₃ can cause testicular and LC toxicity through mitochondrial-related pathways and oxidative stress indices as well as downregulation of androgenic-related genes in mice and isolated LCs. These results could lead to the development of preventive/therapeutic procedures against As₂O₃-induced reproductive toxicity. Graphical Abstract Mohammad Mehdi Ommati and Reza Heidari contributed equally to this study.

Phenylethanol glycosides from Cistanche tubulosa improved reproductive dysfunction by regulating testicular steroids through CYP450-3β-HSD pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cistanche tubulosa (Schenk) R. Wight has been used frequently in traditional folk medicine for treatment of male sexual dysfunction (MSD). Phenylethanol glycosides, the main components of C. tubulosa, possess a variety of pharmacological activities due to their multiple properties. However, the underlying mechanism by which phenylethanol glycosides from C. tubulosa (CPhGs) regulates testicular steroids has not been elucidated to date.

AIM OF THE STUDY

This study is to determine whether CPhGs promotes the reproductive functions of mice through CYP450-3β-HSD pathway of testosterone synthesis.

MATERIALS AND METHODS

The major compositions of C. tubulosa (CPhGs) were quantified by high performance liquid chromatography (HPLC). The model of reproductive injury in mice were induced by injection of hydrocortisone (HCT). Different doses of CPhGs (72, 145 and 289 mg/kg) and testosterone propionate (TP, positive control drug) were administrated intragastrically for 14 d. The reproductive functions (erectile incubation period, capture and ejaculation incubation period, number of captures and ejaculations) and organ weights (testicle, epididymis, seminal vesicle and penis) were then determined. The levels of luteinizing hormone and testosterone in serum were quantified by radioimmunoassay. The key enzymes in testosterone synthesis pathways such as steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side chain cleavage enzyme (P450scc/CYP11A1) and 3β-hydroxysteroid dehydrogenase (3β-HSD) in the testis were assessed by immunofluorescence (IF) staining or/and Western blot (WB) analysis.

RESULTS

The results illustrated that the low dose of CPhGs (72 mg/kg) had no significant protective effect against the reproductive injury caused by HCT, while the moderate dose of CPhGs (145 mg/kg) improved the damaged reproductive ability and the declined levels of luteinizing hormone and testosterone in the model mice (P < 0.001, P < 0.05, respectively). In particular, high dose of CPhGs (289 mg/kg) was most effective in improving HCT-induced changes in body weight (P < 0.01), reducing the incubation period of the erectile (P < 0.001), capture (P < 0.05) and ejaculation (P < 0.01), and increasing the number of captures and ejaculations (P < 0.01, P < 0.05, respectively). The weights of testcle, epididymis, seminal vesicle and penis (P < 0.001, P < 0.01, P < 0.01, P < 0.001, respectively) were improved by high dose of CPhGs. The levels of testosterone and its upstream luteinizing hormone were up-regulated by high dose of CPhGs (P < 0.001). Meanwhile, the expressions of the key steroidogenic enzymes including CYP11A1 and 3β-HSD were significantly up-regulated after CPhGs treatment (P < 0.001), demonstrated that CPhGs exerted the effect through enhancing testosterone biosynthesis via CYP450-3β-HSD pathway.

CONCLUSIONS

CPhGs could significantly protect against HCT-induced deleterious reproductive dysfunction and testis injury. The protective effects were exerted by up-regulating synthesis of testosterone via the CYP450-3β-HSD pathway in Leydig cells.

17β-Hydroxysteroid dehydrogenase type 12a responsible for testicular 11-ketotestosterone synthesis in the Japanese eel, Anguilla japonica

The production of 11-ketotestosterone (11KT), an important steroid hormone in piscine spermatogenesis, is regulated by the pituitary gonadotropins [Gths: follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh)] and it is synthesized by catalytic reactions involving several steroidogenic enzymes. Among these enzymes, the role of 17β-hydroxysteroid dehydrogenases (Hsd17bs) that exhibited 17-ketosteroid reducing activity (17KSR activity) responsible for 11KT synthesis is still poorly understood. In the present study, for the deeper understanding of testicular 11KT biosynthesis, we first investigated the steroidogenic pathway to produce 11KT in Japanese eel testis. In vitro incubation of the testis with androstenedione (A4) and the subsequent analysis of the metabolites by thin-layer chromatography indicated that 11KT was synthesized from A4 via 11β-hydroxyandrostenedione (11OHA4) and 11-ketoandrostenedione (11KA4), which indicated that the steroidogenic enzyme exhibiting the 17KSR activity responsible for converting 11KA4 to 11KT is crucial for 11KT production. Subsequently, cDNAs encoding three candidate enzymes, Hsd17b type3 (Hsd17b3), Hsd17b type12a (Hsd17b12a), and 20β-hydroxysteroid dehydrogenase type2 (Hsd20b2), potentially with the 17KSR activity were isolated and characterized in the Japanese eel. The isolated hsd17b3, hsd17b12a, and hsd20b2 cDNAs putatively encoded 308, 314, and 327 amino acid residues with high homology to those of other vertebrate counterparts, respectively. The Hsd17b3, Hsd17b12a, and Hsd20b2 expressed either in HEK293T or in Hepa-E1 converted 11KA4 to 11KT. Tissue-distribution analysis by quantitative real time PCR revealed that hsd17b12a and hsd20b2 mRNAs were detected in the testis, while hsd17b3 mRNA was not detectable. Furthermore, we examined the effects of Gths on the 17KSR activity and the expression of the candidate genes in the immature testis. The 17KSR activity was upregulated by administration of Gths. Furthermore, only expression of hsd17b12a among three candidates was upregulated by Gths as well as the 17KSR activity. These findings strongly suggested that Hsd17b12a is one of the enzymes with 17KSR activity responsible for 11KT synthesis in the testis of Japanese eel.

Interactions of 17β-Hydroxysteroid Dehydrogenase Type 10 and Cyclophilin D in Alzheimer's Disease

The nucleus-encoded 17β-hydroxysteroid dehydrogenase type 10 (17β-HSD10) regulates cyclophilin D (cypD) in the mitochondrial matrix. CypD regulates opening of mitochondrial permeability transition pores. Both mechanisms may be affected by amyloid β peptides accumulated in mitochondria in Alzheimer's disease (AD). In order to clarify changes occurring in brain mitochondria, we evaluated interactions of both mitochondrial proteins in vitro (by surface plasmon resonance biosensor) and detected levels of various complexes of 17β-HSD10 formed in vivo (by sandwich ELISA) in brain mitochondria isolated from the transgenic animal model of AD (homozygous McGill-R-Thy1-APP rats) and in cerebrospinal fluid samples of AD patients. By surface plasmon resonance biosensor, we observed the interaction of 17β-HSD10 and cypD in a direct real-time manner and determined, for the first time, the kinetic parameters of the interaction (ka 2.0 × 105 M1s-1, kd 5.8 × 104 s-1, and KD 3.5 × 10-10 M). In McGill-R-Thy1-APP rats compared to controls, levels of 17β-HSD10-cypD complexes were decreased and those of total amyloid β increased. Moreover, the levels of 17β-HSD10-cypD complexes were decreased in cerebrospinal fluid of individuals with AD (in mild cognitive impairment as well as dementia stages) or with Frontotemporal lobar degeneration (FTLD) compared to cognitively normal controls (the sensitivity of the complexes to AD dementia was 92.9%, that to FTLD 73.8%, the specificity to AD dementia equaled 91.7% in a comparison with the controls but only 26.2% with FTLD). Our results demonstrate the weakened ability of 17β-HSD10 to regulate cypD in the mitochondrial matrix probably via direct effects of amyloid β. Levels of 17β-HSD10-cypD complexes in cerebrospinal fluid seem to be the very sensitive indicator of mitochondrial dysfunction observed in neurodegeneration but unfortunately not specific to AD pathology. We do not recommend it as the new biomarker of AD.

Molecular Mechanisms: Connections between Nonalcoholic Fatty Liver Disease, Steatohepatitis and Hepatocellular Carcinoma

Nonalcoholic fatty liver disease (NAFLD), including nonalcoholic steatohepatitis (NASH), causes hepatic fibrosis, cirrhosis and hepatocellular carcinoma (HCC). The patatin-like phospholipase-3 (PNPLA3) I148M sequence variant is one of the strongest genetic determinants of NAFLD/NASH. PNPLA3 is an independent risk factor for HCC among patients with NASH. The obesity epidemic is closely associated with the rising prevalence and severity of NAFLD/NASH. Furthermore, metabolic syndrome exacerbates the course of NAFLD/NASH. These factors are able to induce apoptosis and activate immune and inflammatory pathways, resulting in the development of hepatic fibrosis and NASH, leading to progression toward HCC. Small intestinal bacterial overgrowth (SIBO), destruction of the intestinal mucosa barrier function and a high-fat diet all seem to exacerbate the development of hepatic fibrosis and NASH, leading to HCC in patients with NAFLD/NASH. Thus, the intestinal microbiota may play a role in the development of NAFLD/NASH. In this review, we describe recent advances in our knowledge of the molecular mechanisms contributing to the development of hepatic fibrosis and HCC in patients with NAFLD/NASH.

Evaluation of 17β-hydroxysteroid dehydrogenase activity using androgen receptor-mediated transactivation

17β-Hydroxysteroid dehydrogenases (17β-HSDs) catalyze the reduction of 17-ketosteroids and the oxidation of 17β-hydroxysteroids to regulate the production of androgens and estrogens. Among them, 17β-HSD type 3 (HSD17B3) is expressed almost exclusively in testicular Leydig cells and contributes to development of male sexual characteristics by converting androstenedione (A4) to testosterone (T). Mutations of HSD17B3 genes cause a 46,XY disorder of sexual development (46,XY DSD) as a result of low T production. Therefore, the evaluation of 17β-HSD3 enzymatic activity is important for understanding and diagnosing this disorder. We adapted a method that easily evaluates enzymatic activity of 17β-HSD3 by quantifying the conversion from A4 to T using androgen receptor (AR)-mediated transactivation. HEK293 cells were transduced to express human HSD17B3, and incubated medium containing A4. Depending on the incubation time with HSD17B3-expressing cells, the culture media progressively increased luciferase activities in CV-1 cells, transfected with the AR expression vector and androgen-responsive reporter. Culture medium from HSD17B1 and HSD17B5-expressing cells also increased the luciferase activities. This system is also applicable to detect the conversion of 11-ketoandrostenedione to 11-ketotestosterone by HSD17B3. Establishment of HEK293 cells expressing various missense mutations in the HSD17B3 gene associated with 46,XY DSD revealed that this system is effective to evaluate the enzymatic activities of mutant proteins.

Steroid enzyme and receptor expression and regulations in breast tumor samples - A statistical evaluation of public data

In spite of the significant progress of estrogen-dependent breast cancer (BC) treatment, aromatase inhibitor resistance is a major problem limiting the clinical benefit of this frontier endocrine-therapy. The aim of this study was to determine the differential expression of steroid-converting enzymes between tumor and adjacent normal tissues, as well as their correlation in modulating intratumoral steroid-hormone levels in post-menopausal estrogen-dependent BC. RNA sequencing dataset (n = 1097) of The-Cancer-Genome-Atlas (Breast Invasive Carcinoma) retrieved through the data portal of Genomic Data Commons was used for differential expressions and expression correlation analyses by Mann-Whitney U and Spearman's rank test, respectively. The results showed significant up-regulation of 17β-HSD7 (2.50-fold, p < 0.0001) in BC, supporting its effect in sex-hormone control. Besides, suppression of 11β-HSD1 expression (-8.29-fold, p < 0.0001) and elevation of 11β-HSD2 expression (2.04-fold, p < 0.0001) provide a low glucocorticoid environment diminishing BC anti-proliferation. Furthermore, 3α-HSDs were down-regulated (-1.59-fold, p < 0.01; -8.18-fold, p < 0.0001; -33.96-fold, p < 0.0001; -31.85-fold, p < 0.0001 for type 1-4, respectively), while 5α-reductases were up-regulated (1.41-fold, p < 0.0001; 2.85-fold, p < 0.0001; 1.70-fold, p < 0.0001 for type 1-3, respectively) in BC, reducing cell proliferation suppressers 4-pregnenes, increasing cell proliferation stimulators 5α-pregnanes. Expression analysis indicates significant correlations between 11β-HSD1 with 3α-HSD4 (r = 0.605, p < 0.0001) and 3α-HSD3 (r = 0.537, p < 0.0001). Significant expression correlations between 3α-HSDs were also observed. Our results systematically present the regulation of steroid-converting enzymes and their roles in modulating the intratumoral steroid-hormone levels in BC with a vivid 3D-schema, supporting novel therapy targeting the reductive 17β-HSD7 and proposing a new combined therapy targeting 11β-HSD2 and 17β-HSD7.

Mitochondrial dysfunction and Alzheimer's disease: prospects for therapeutic intervention

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease and has become a major socioeconomic issue in many developed countries. Currently available therapeutic agents for AD provide only symptomatic treatments, mainly because the complete mechanism of the AD pathogenesis is still unclear. Although several different hypotheses have been proposed, mitochondrial dysfunction has gathered interest because of its profound effect on brain bioenergetics and neuronal survival in the pathophysiology of AD. Various therapeutic agents targeting the mitochondrial pathways associated with AD have been developed over the past decade. Although most of these agents are still early in the clinical development process, they are used to restore mitochondrial function, which provides an alternative therapeutic strategy that is likely to slow the progression of the disease. In this mini review, we will survey the AD-related mitochondrial pathways and their small-molecule modulators that have therapeutic potential. We will focus on recently reported examples, and also overview the current challenges and future perspectives of ongoing research. [BMB Reports 2020; 53(1): 47-55].

E2 -mediated EMT by activation of β-catenin/Snail signalling during the development of ovarian endometriosis

Endometriosis is an oestrogen-dependent disease, and epithelial-mesenchymal transition (EMT) is involved in the process of endometriosis. Whether oestrogen could induce EMT in endometriosis remains largely unknown. Here, we reported that up-regulated expression of EMT markers in ovarian chocolate cyst is accompanied by high expression 17β-hydroxysteroid dehydrogenase 1 (17β-HSD1), and exposure of primary human endometrial epithelial cells to oestradiol conditions could promote EMT occurrence and activate both β-catenin and Snail signalling. Furthermore, we found nuclear β-catenin and Snail expression was closely linked in ovarian endometriosis, and β-catenin knockdown abrogated oestrogen-induced Snail mediated EMT in vitro. This is due to that β-catenin/ TCF-3 could bind to Snail promoter and activate its transcription. These results suggested that β-catenin signalling functions as the Snail activator and plays a critical role in oestradiol-induced EMT in endometriosis.

Physiological effects of 5α-dihydrotestosterone in male mummichog (Fundulus heteroclitus) are dose and time dependent

Numerous anthropogenic sources, such as pulp mill and sewage treatment effluents, contain androgenic endocrine disrupting compounds that alter the reproductive status of aquatic organisms. The current study injected adult male mummichog (Fundulus heteroclitus) with 0 (control), 1 pg/g, 1 ng/g or 1 μg/g body weight of the model androgen 5α-dihydrotestosterone (DHT) with the intent to induce a period of plasma sex hormone depression, a previously-observed effect of DHT in fish. A suite of gonadal steroidogenic genes were assessed during sex hormone depression and recovery. Fish were sampled 6, 12, 16, 18, 24, 30 and 36 h post-injection, and sections of testis tissue were either snap frozen immediately or incubated for 24 h at 18 °C to determine in vitro gonadal hormone production and then frozen. Plasma testosterone (T) and 11-ketotestosterone (11KT) were depressed beginning 24 h post-injection. At 36 h post-injection plasma T remained depressed while plasma 11KT had recovered. In snap frozen tissue there was a correlation between plasma sex hormone depression and downregulation of key steroidogenic genes including steroidogenic acute regulatory protein (star), cytochrome P450 17a1 (cyp17a1), 3β-hydroxysteroid dehydrogenase (3βhsd), 11β-hydroxysteroid dehydrogenase (11βhsd) and 17β-hydroxysteroid dehydrogenase (17βhsd). Similar to previous studies, 3βhsd was the first and most responsive gene during DHT exposure. Gene responses from in vitro tissue were more variable and included the upregulation of 3βhsd, 11βhsd and star during the period of hormone depression. The differential expression of steroidogenic genes from the in vitro testes compared to the snap frozen tissues may be due to the lack of regulators from the hypothalamo-pituitary-gonadal axis present in whole-animal systems. Due to these findings it is recommended to use snap frozen tissue, not post-incubation tissue from in vitro analysis, for gonadal steroidogenic gene expression to more accurately reflect in vivo responses.

In vitro study of interaction of 17β-hydroxysteroid dehydrogenase type 10 and cyclophilin D and its potential implications for Alzheimer's disease

In early stages of Alzheimer's disease (AD), amyloid-β (Aβ) accumulates in neuronal mitochondria where it interacts with a number of biomolecules including 17beta-hydroxysteroide dehydrogenase 10 (17β-HSD10) and cyclophilin D (cypD). It has been hypothesized that 17β-HSD10 interacts with cypD preventing it from opening mitochondrial permeability transition pores and that its regulation during AD may be affected by the accumulation of Aβ. In this work, we demonstrate for the first time that 17β-HSD10 and cypD form a stable complex in vitro. Furthermore, we show that factors, such as pH, ionic environment and the presence of Aβ, affect the ability of 17β-HSD10 to bind cypD. We demonstrate that K+ and Mg2+ ions present at low levels may facilitate this binding. We also show that different fragments of Aβ (Aβ1-40 and Aβ1-42) affect the interaction between 17β-HSD10 and cypD differently and that Aβ1-42 (in contrast to Aβ1-40) is capable of simultaneously binding both 17β-HSD10 and cypD in a tri-complex.

Mechanical stretch enhances sex steroidogenesis in C2C12 skeletal muscle cells

Skeletal muscle contains estrogens and estrogen synthesis-related enzymes. However, it has not been reported whether myoblasts cultured in vitro also express these enzymes. The purpose of the current study was to address these issues and to explore the effects of mechanical stretch on the enzyme system. The in vitro cultured C₂C₁₂ mouse myoblasts were divided into the control, stretch, testosterone and stretch plus testosterone groups. Cells in the stretch and stretch plus testosterone groups were mechanically stretched with the Flexercell cell stress loading device at an amplitude of 10% and in a frequency of 0.5 Hz for 8 h. Cells in the testosterone and stretch plus testosterone groups were incubated with 100 nM testosterone for 24 h before distraction. Following the treatments, cell proliferation and estradiol levels, as well as the expressions of 17β-hydroxysteroid (17β-HSD), 3β-hydroxysteroid (3β-HSD) and aromatase were analyzed. Compared to the control, the cell proliferation in all experimental groups increased significantly, the estradiol levels in the mechanically stretched groups were significantly higher, and, moreover, the estradiol levels were positively correlated with the cell proliferation (r = 0.615, p < 0.01). Additionally, analyses of aromatase protein and mRNA showed that, compared to the control, their levels were significantly increased upon stretching and testosterone exposure. Similarly, the protein and mRNA levels of both 3β-HSD and 17β-HSD in the stretched cells differed significantly from the control. In the presence of aromatase and 5α-reductase inhibitors, the protein and mRNA levels of these enzymes altered significantly compared to the control. Conclusions: Steroid synthases were detected in the C₂C₁₂ myoblasts cultured in vitro, the synthesized estrogen was closely related to the cell proliferation, and mechanical stretch was the external factor that affected the expression of the estrogen synthesis-related enzymes.

Features of the fetal gonad in androgen synthesis in the postpubertal testis are preserved in complete androgen insensitivity syndrome due to a novel genetic splice site donor variant in androgen receptor gene intron 1

Mutations in the X-linked androgen receptor (AR) gene cause complete androgen insensitivity syndrome (CAIS). CAIS may cause congenital sexual development disorder, which frequently develops into testicular tumors. Here, we describe a novel splice-site intron 1 mutation in AR leading to improper splicing and AR protein absence in CAIS gonads. We characterized a patient's postpubertal gonadal steroidogenic enzyme expression profile. Localization of both CYP11A1 and CYP17A1 enzymes was restricted to both Leydig tumor cells and adjacent to tumor gonadal tissues. Sertoli cells of the CAIS gonad showed abundant HSD17B3 protein, which is an adult Leydig cell marker that enables the conversion of androstenedione to testosterone. Such HSD17B3 expression is typical for fetal-type Sertoli cells in rodents. The postpubertal CAIS gonad of our patient was completely devoid of androgen signaling pathway activity. Plausibly, the postpubertal Leydig cells consisted of two distinct cell populations: postpubertal fetal-type Leydig cells that persisted as androgen-independent cells and immature adult Leydig cells that failed to differentiate. Taken together, in this CAIS postpubertal testis, both Leydig and fetal-type Sertoli cells participated in testosterone production. Our results indicate the importance of molecular analysis as well as the characterization of steroidogenic enzyme profiling in the CAIS patient's gonad.

The Non-Aromatic Δ5-Androstenediol Derivative of Dehydroepiandrosterone Acts as an Estrogen Agonist in Neonatal Rat Osteoblasts through an Estrogen Receptor α-related Mechanism

Purpose: It has been proposed that DHEA influences bone formation through, bioconversion to 17β-estradiol; however, DHEA is converted to Δ5-androstenediol (Δ5-Adiol), a metabolite with estrogenic potential involved in diverse biological process. To gain new insight into the role of Δ5-Adiol in bone cells, we examined DHEA and Δ5-Adiol effects in neonatal rat and human hFOB1.19 osteoblasts. Methods: Osteoblast activity was assessed by analyzing proliferation, alkaline phosphatase activity, and expression of OSX and ALPL. We also examined binding affinities for osteoblast-ER and transcriptional activation of human (h)ERα, hERβ or hAR in U2-OS cells. Results: The most striking finding was that Δ5-Adiol had greater stimulatory effect than DHEA on rat osteoblast proliferation and differentiation, as well as ALPL expression in human osteoblasts. Interestingly, the Δ5-Adiol or DHEA-induced effects were not precluded with letrozole or trilostane, consistent with bioconversion of DHEA to Δ5-Adiol due to elevated expression of Hsd17b1 in neonatal rat osteoblasts, suggesting a high level of 17β-hydroxysteroid dehydrogenase type 1 activity. Conversely, Δ5-Adiol and DHEA-induced proliferative effects were inhibited with ICI 182780 alone or combined with trilostane, which correlates with the higher binding affinity of Δ5-Adiol for ER compared to DHEA. Furthermore, Δ5-Adiol showed a greater relative agonist activity for hERα than for hERβ or hAR. Conclusion: This study is the first to show that a bioactive DHEA derivative stimulates E₂-dependent osteoblast activities, including proliferation and differentiation in rat and human osteoblasts, through ERα-related mechanisms.

Metabolic engineering of Rhodococcus ruber Chol-4: A cell factory for testosterone production

Rhodococcus ruber Chol-4 is a potent steroid degrader that has a great potential as a biotechnological tool. As proof of concept, this work presents testosterone production from 4-androstene-3,17-dione by tailoring innate catabolic enzymes of the steroid catabolism inside the strain. A R. ruber quadruple mutant was constructed in order to avoid the breakage of the steroid nucleus. At the same time, an inducible expression vector for this strain was developed. The 17-ketoreductase gene from the fungus Cochliobolus lunatus was cloned and overexpressed in this vector. The engineered strain was able to produce testosterone from 4-androstene-3,17-dione using glucose for cofactor regeneration with a molar conversion of 61%. It is important to note that 91% of the testosterone was secreted outside the cell after 3 days of cell biotransformation. The results support the idea that Rhodococcus ruber Chol-4 can be metabolically engineered and can be used for the production of steroid intermediates.

A highly efficient step-wise biotransformation strategy for direct conversion of phytosterol to boldenone

Collaborative microbial communities are ubiquitous in nature and exhibit appealing functions for enhanced production of natural products, which provides new possibility for biotechnology development. In this study, we bridged Mycobacterium neoaurum with Pichia pastoris to establish a step-wise biotransformation strategy for efficient biosynthesis of boldenone (BD) from phytosterol (PS). Firstly, the producing strains were rationally designed with overexpression of 3-ketosteroid-Δ1-dehydrogenase (KsdD) and 17β-hydroxysteroid dehydrogenase (17βHSD) in M. neoaurum and P. pastoris, respectively. Then, to shorten the total biotransformation process and provide reducing power, semi-batch fermentation strategy and glucose supplementation strategy were introduced at side-chain degradation stage and carbonyl reduction stage, respectively. Under the optimal transformation conditions, the productivity of BD was increased from 10% to 76% and the total biotransformation process was shortened by 41.7%, which is the shortest among the ever reported. Our results demonstrated an excellent biological strategy for production of many other valuable microbial products from bioresources.

Local estrogen metabolism (intracrinology) in endometrial cancer: A systematic review

Endometrial cancer (EC) is the most common malignancy of the female gynaecological tract and increased exposure to estrogens is a risk factor. EC cells are able to produce estrogens locally using precursors like, among others, adrenal steroids present in the serum. This is referred to as local estrogen metabolism (or intracrinology) and consists of a complex network of multiple enzymes. Particular relevant to the final generation of active estrogens in endometrial cells are: steroid sulfatase (STS), estrogen sulfotransferase (SULT1E1), aromatase (CYP19A1), 17β-hydroxysteroid dehydrogenase (HSD17B) type 1 and type 2. During the last decades, a plethora of studies explored the level of these enzymes in EC but contrasting data were reported, which generated vigorous debate and controversies. Several reviews attempted at clarifying some of the debated issues, but published reviews are based on investigator-defined bibliography selection and not on systematic analysis. Therefore, we performed a systematic review of the literature reporting about the level of STS, SULT1E1, CYP19A1, HSD17B1 and HSD17B2 in EC. Additional intracrine enzymes and networks (e.g., HSD17Bs other than types 1 and 2, aldo-keto reductases, progesterone and androgen metabolism) were non-systematically reviewed as well.

The role of 17βHSDs in breast tissue and breast cancers

The family of seventeen beta hydroxysteroid dehydrogenase enzymes has a long and diverse history in breast and breast cancer research. Given the known dependence of the breast on steroid signalling and intracrine steroid metabolism these enzymes are considered to be essential local fine tuners of overall steroid balance in the tissue. This review will cover the current state of knowledge regarding the expression, clinical effect and biological regulation of enzymes in both cancerous and normal states. In addition we will also cover the current state of knowledge regarding 17βHSD actions in the often neglected adipose and stromal components of tumours.

Role of HSD17B13 in the liver physiology and pathophysiology

17β-Hydroxysteroid dehydrogenases (HSD17Bs) comprise a large family of 15 members that are mainly involved in sex hormone metabolism. Some HSD17Bs enzymes also play key roles in cholesterol and fatty acid metabolism. Recent study showed that hydroxysteroid 17β-dehydrogenase 13 (HSD17B13), an enzyme with unknown biological function, is a novel liver-specific lipid droplet (LD)-associated protein in mouse and humans. HSD17B13 expression is markedly upregulated in patients and mice with non-alcoholic fatty liver disease (NAFLD). Hepatic overexpression of HSD17B13 promotes lipid accumulation in the liver. In this review, we summarize recent progress regarding the role of HSD17B13 in the regulation of hepatic lipid homeostasis and discuss genetic, genomic and proteomic evidence supporting the pathogenic role of HSD17B13 in NAFLD. We also emphasize its potential as a biomarker of advanced liver disease, such as non-alcoholic steatohepatitis (NASH) and liver cancer.

17β-Hydroxysteroid dehydrogenases and neurosteroid metabolism in the central nervous system

17β-Hydroxysteroid dehydrogenases are indispensable for downstream enzyme steps of the neurosteroidogenesis. Neurosteroids are synthesized de novo in neurons and glia from cholesterol transported into mitochondria, or by conversion from proneurosteroids, e. g. dehydroepiandrosterone (DHEA) and pregnenolone, through the same metabolic pathway as revealed in the de novo neurosteroidogenesis. Hormonal steroids generated from endocrine glands are transported into brain from the circulation to exert neuronal activity via genomic pathway, whereas neurosteroids produced in brain cells without genomic targets identified could bind to cell surface targets, e.g., GABA_A or NMDA receptors and elicit antidepressant, anxiolytic, anticonvulsant and anesthetic effects by regulating neuroexcitability. In a broad sense, neurosteroids include hormonal steroids in brain, and they are irrespective of origin playing important roles in brain development including neuroprotection, neurogenesis and neural plasticity. They are also a critical element in cognitive and memory functions. Mitochondrial 17β-HSD10, encoded by the HSD17B10 gene mapping to Xp11.2, is found in various brain regions, essential for the maintenance of neurosteroid homeostasis. Mutations identified in this gene resulted in two distinct brain diseases, namely HSD10 deficiency and MRXS10, of which clinical presentations and pathogenetic mechanisms are quite different. Since elevated levels of 17β-HSD10 was found in brains of Alzheimer's disease patients and AD mouse model, it may also act as an adverse factor in the AD pathogenesis due to an imbalance of neurosteroid metabolism.