Synthesis of atypical bile acids for use as investigative tools for the genetic defect of 3β-hydroxy-Δ(5)-C27-steroid oxidoreductase deficiency

Integration of RNAi and RNA-seq uncovers the regulation mechanism of DDX20 on vitellogenin expression in Scylla paramamosain

Vitellogenesis in crustaceans is controlled by several steroid hormones. In humans, the expression of SF-1, a gene that regulates gonadal development and the synthesis of steroid hormones, is affected by DDX20. However, how the homologous gene FTZ-F1 is regulated by DDX20 and its association with vitellogenesis remains unknown in the mud crab Scylla paramamosain. In this study, SpDDX20 and SpFTZ-F1 were identified in the transcriptome of mature ovarian tissue from the mud crab. qRT-PCR results revealed that the expression levels of SpFTZ-F1 and SpVTG in the ovaries of crab in the experimental group injected with dsDDX20 (EO) were significantly higher (P < 0.05) than those in the negative control group injected with dsEGFP (NO) and the blank control group injected with SPSS (BO). The differentially expressed genes (DEGs) identified by comparative transcriptome analysis of the EO group and NO group were enriched into five pathways related to ovarian steroidogenesis. The expression of CYP17, CYP3A4, CYP1A1 and 3β-HSD were up-regulated in pathways related to steroid hormone production and biosynthesis. The expression of the INSR, IRS and PI3K genes in the insulin signaling pathway were significantly increased (P < 0.05). The expression level of the TGF-β gene was up-regulated (P < 0.05) in the transforming growth factor pathway, whereas the expression level of the Smad2 gene was down-regulated (P < 0.05). The expression of GnRHR, GS, AC and PKA genes in the gonadotropin-releasing hormone signaling pathway were up-regulated. Our data provide a foundation for investigating the relationship between DDX20 and FTZ-F1 in the regulation of vitellogenin expression in S. paramamosain.

Synthesis and biological activity of cyclopropyl Δ7-dafachronic acids as DAF-12 receptor ligands

The four cyclopropyl stereoisomers of Δ7-dafachronic acids were prepared from the bile acid hyodeoxycholic acid and employed as chemical tools to exploit the importance of the orientation and spatial disposition of the carboxyl tail and the C25-methyl group for the binding at the DAF-12 receptor. The synthesis route was based on (a) Walden inversion and stereoselective PtO₂-hydrogenation to convert the L-shaped 5β-cholanoid scaffold into the planar 5α-sterol intermediate; (b) two-carbon homologation of the side chain by Wittig and cyclopropanation reaction; and (c) formation of the 3-keto group and Δ7 double bond. The synthesized isomers were isolated and tested for their activity as DAF-12 ligands by AlphaScreen assays. Results showed a significant loss of potency and efficacy for all the four stereoisomers when compared to the parent endogenous ligand. Computational analysis has evidenced the configurational and conformational arrangement of both the carboxylic and the C25-methyl group of dafachronic acids as key structural determinants for DAF-12 binding and activation.

Study on synthesis of key squalamine intermediate 7α, 24R-dihydroxy-5α-cholestan-3-one

A facile novel strategy has been developed to obtain a key intermediate of squalamine, 7α, 24R -dihydroxy-5α-cholestan-3-one, starting from methyl Δ⁵-3β-hydroxycholanate. The pure product was successfully synthesized and separated from the C-24 position epimers in good purity, d.e.% and yield.

Bile acid homeostasis controls CAR signaling pathways in mouse testis through FXRalpha

Bile acids (BAs) are molecules with endocrine activities controlling several physiological functions such as immunity, glucose homeostasis, testicular physiology and male fertility. The role of the nuclear BA receptor FXRα in the control of BA homeostasis has been well characterized. The present study shows that testis synthetize BAs. We demonstrate that mice invalidated for the gene encoding FXRα have altered BA homeostasis in both liver and testis. In the absence of FXRα, BA exposure differently alters hepatic and testicular expression of genes involved in BA synthesis. Interestingly, Fxrα-/- males fed a diet supplemented with BAs show alterations of testicular physiology and sperm production. This phenotype was correlated with the altered testicular BA homeostasis and the production of intermediate metabolites of BAs which led to the modulation of CAR signaling pathways within the testis. The role of the CAR signaling pathways within testis was validated using specific CAR agonist (TCPOBOP) and inverse agonist (androstanol) that respectively inhibited or reproduced the phenotype observed in Fxrα-/- males fed BA-diet. These data open interesting perspectives to better define how BA homeostasis contributes to physiological or pathophysiological conditions via the modulation of CAR activity.

Δ(5)-Cholenoyl-amino acids as selective and orally available antagonists of the Eph-ephrin system

The Eph receptor-ephrin system is an emerging target for the development of novel anti-angiogenic therapies. Research programs aimed at developing small-molecule antagonists of the Eph receptors are still in their initial stage as available compounds suffer from pharmacological drawbacks, limiting their application in vitro and in vivo. In the present work, we report the design, synthesis and evaluation of structure-activity relationships of a class of Δ(5)-cholenoyl-amino acid conjugates as Eph-ephrin antagonists. As a major achievement of our exploration, we identified N-(3β-hydroxy-Δ(5)-cholen-24-oyl)-L-tryptophan (UniPR1331) as the first small molecule antagonist of the Eph-ephrin system effective as an anti-angiogenic agent in endothelial cells, bioavailable in mice by the oral route and devoid of biological activity on G protein-coupled and nuclear receptors targeted by bile acid derivatives.

Tandem Mass Spectrometric Determination of Atypical 3β-Hydroxy-Δ5-Bile Acids in Patients with 3β-Hydroxy-Δ5-C27-Steroid Oxidoreductase Deficiency: Application to Diagnosis and Monitoring of Bile Acid Therapeutic Response

BACKGROUND

3β-Hydroxy-Δ5-C27-steroid oxidoreductase (HSD3B7) deficiency, a progressive cholestatic liver disease, is the most common genetic defect in bile acid synthesis. Early diagnosis is important because patients respond to oral primary bile acid therapy, which targets the negative feedback regulation for bile acid synthesis to reduce the production of hepatotoxic 3β-hydroxy-Δ5-bile acids. These atypical bile acids are highly labile and difficult to accurately measure, yet a method for accurate determination of 3β-hydroxy-Δ5-bile acid sulfates is critical for dose titration and monitoring response to therapy.

METHODS

We describe a electrospray ionization LC-MS/MS method for the direct measurement of atypical 3β-hydroxy-Δ5-bile acid sulfates in urine from patients with HSD3B7 deficiency that overcomes the deficiencies of previously used GC-MS methods.

RESULTS

Separation of sulfated 3β-hydroxy-Δ5-bile acids was achieved by reversed-phase HPLC in a 12-min analytical run. The mean (SE) urinary concentration of the total 3β-sulfated-Δ5-cholenoic acids in patients with HSD3B7 deficiency was 4650 (1711) μmol/L, approximately 1000-fold higher than in noncholestatic and cholestatic patients with intact primary bile acid synthesis. GC-MS was not reliable for measuring 3β-hydroxy-Δ5-bile acid sulfates; however, direct analysis of urine by fast atom bombardment mass spectrometry yielded meaningful semiquantitative assessment of urinary excretion.

CONCLUSIONS

The tandem mass spectrometry method described here for the measurement of 3β-hydroxy-Δ5-bile acid sulfates in urine can be applied to the diagnosis and accurate monitoring of responses to primary bile acid therapy in HSD3B7 patients.

Combining ligand- and structure-based approaches for the discovery of new inhibitors of the EPHA2-ephrin-A1 interaction

The EPH receptor A2 (EPHA2) represents an attractive anticancer target. With the aim to identify novel EPHA2 receptor antagonists, a virtual screening campaign, combining shape-similarity and docking calculations, was conducted on a set of commercially available compounds. A combined score, taking into account both ligand- and structure-based results, was then used to identify the most promising candidates. Two compounds, selected among the best-ranked ones, were identified as EPHA2 receptor antagonists with micromolar affinity.