Supreme glutathione-dependent ketosteroid isomerase in the yellow-fever transmitting mosquito Aedes aegypti.

The steroid hormone ecdysone is essential for the reproduction and survival of insects. The hormone is synthesized from dietary sterols such as cholesterol, yielding ecdysone in a series of consecutive enzymatic reactions. In the insect orders Lepidoptera and Diptera a glutathione transferase called Noppera-bo (Nobo) plays an essential, but biochemically uncharacterized, role in ecdysteroid biosynthesis. The Nobo enzyme is consequently a possible target in harmful dipterans, such as disease-carrying mosquitoes. Flavonoid compounds inhibit Nobo and have larvicidal effects in the yellow-fever transmitting mosquito Aedes aegypti, but the enzyme is functionally incompletely characterized. We here report that within a set of glutathione transferase substrates the double-bond isomerase activity with 5-androsten-3,17-dione stands out with an extraordinary specific activity of 4000 µmol min-1 mg-1. We suggest that the authentic function of Nobo is catalysis of a chemically analogous ketosteroid isomerization in ecdysone biosynthesis.

Importance of 3ß-hydroxysteroid dehydrogenases and their clinical use in prostate cancer.

Androgen receptor signaling is crucial for the development of treatment resistance in prostate cancer. Among steroidogenic enzymes, 3ß-hydroxysteroid dehydrogenases (3ßHSDs) play critical roles in extragonadal androgen synthesis, especially 3ßHSD1. Increased expression of 3ßHSDs is observed in castration-resistant prostate cancer tumors compared with primary prostate tumors, indicating their involvement in castration resistance. Recent studies link 3ßHSD1 to resistance to androgen receptor signaling inhibitors. The regulation of 3ßHSD1 expression involves various factors, including transcription factors, microenvironmental influences, and posttranscriptional modifications. Additionally, the clinical significance of HSD3B1 genotypes, particularly the rs1047303 variant, has been extensively studied. The impact of HSD3B1 genotypes on treatment outcomes varies according to the therapy administered, suggesting the potential of HSD3B1 genotyping for personalized medicine. Targeting 3ßHSDs may be a promising strategy for prostate cancer management. Overall, understanding the roles of 3ßHSDs and their genetic variations may enable the development and optimization of novel treatments for prostate cancer.

Bond Bundle Analysis of Ketosteroid Isomerase.

Bond bundle analysis is used to investigate enzymatic catalysis in the ketosteroid isomerase (KSI) active site. We identify the unique bonding regions in five KSI systems, including those exposed to applied oriented electric fields and those with amino acid mutations, and calculate the precise redistribution of electron density and other regional properties that accompanies either enhancement or inhibition of KSI catalytic activity. We find that catalytic enhancement results from promoting both inter- and intra-molecular electron density redistribution, between bond bundles and bond wedges within the KSI-docked substrate molecule, in the forward direction of the catalyzed reaction. Though the redistribution applies to both types of perturbed systems and is thus suggestive of a general catalytic role, we observe that bond properties (e.g., volume vs energy vs electron count) can respond independently and disproportionately depending on the type of perturbation. We conclude that the resulting catalytic enhancement/inhibition proceeds via different mechanisms, where some bond properties are utilized more by one type of perturbation than the other. Additionally, we find that the correlations between bond wedge properties and catalyzed reaction barrier energies are additive to predict those of bond bundles and atomic basins, providing a rigorous grounding for connecting changes in local charge density to resulting shifts in reaction barrier energy.

Chemicals of environmental concern as inhibitors of human placental 3ß-hydroxysteroid dehydrogenase 1 and aromatase: Screening and docking analysis.

Many environmental pollutants act as endocrine-disrupting compounds by inhibiting human placental 3ß-hydroxysteroid dehydrogenase/Δ5-4 isomerase type 1 (HSD3B1) and aromatase (CYP19A1) activities. In this study, we screened 13 chemicals of environmental concern for their ability to inhibit human HSD3B1 and CYP19A1 by measuring the conversion of pregnenolone to progesterone for HSD3B1 activity and the conversion of testosterone to 17ß-estradiol for CYP19A1 activity in human JEG-3 choriocarcinoma cell microsomes. HSD3B1 had an apparent Km of 0.323 µM and an apparent Vmax of 0.111 nmol/mg/min and CYP19A1 had an apparent Km of 56 nM and an apparent Vmax of 0.177 nmol/mg protein/min. 17ß-Estradiol, bisphenol A, and bisphenol AF competitively inhibited HSD3B1 with Ki values of 0.8, 284.1, and 141.2 µM, respectively, while diethylstilbestrol had a mixed inhibition on human HSD3B1 with the Ki of 8.0 µM. Ketoconazole, bisphenol A, and bisphenol AF noncompetitively inhibited CYP19A1 with Ki values of 10.3, 54.4, and 45.7 µM, respectively, while diethylstilbestrol and zearalenone competitively suppressed CYP19A1 with Ki values of 63.0 and 16.6 µM, respectively. Docking analysis showed that 17ß-estradiol, diethylstilbestrol, bisphenol A, and bisphenol AF bound the steroid binding pocket facing the catalytic residues Y155 and K159 of HSD3B1, and that ketoconazole, bisphenol A, and bisphenol AF bound heme binding pocket while diethylstilbestrol and zearalenone bound the steroid binding site of CYP19A1. In conclusion, 17ß-estradiol, diethylstilbestrol, bisphenol A, and bisphenol AF are human HSD3B1 inhibitors, and ketoconazole, zearalenone, diethylstilbestrol, bisphenol A, and bisphenol AF are human CYP19A1 inhibitors.

Ensemble-function relationships to dissect mechanisms of enzyme catalysis.

Decades of structure-function studies have established our current extensive understanding of enzymes. However, traditional structural models are snapshots of broader conformational ensembles of interchanging states. We demonstrate the need for conformational ensembles to understand function, using the enzyme ketosteroid isomerase (KSI) as an example. Comparison of prior KSI cryogenic x-ray structures suggested deleterious mutational effects from a misaligned oxyanion hole catalytic residue. However, ensemble information from room-temperature x-ray crystallography, combined with functional studies, excluded this model. Ensemble-function analyses can deconvolute effects from altering the probability of occupying a state (P-effects) and changing the reactivity of each state (k-effects); our ensemble-function analyses revealed functional effects arising from weakened oxyanion hole hydrogen bonding and substrate repositioning within the active site. Ensemble-function studies will have an integral role in understanding enzymes and in meeting the future goals of a predictive understanding of enzyme catalysis and engineering new enzymes.

Association Between Adrenal-Restrictive HSD3B1 Inheritance and Hormone-Independent Subtypes of Endometrial and Breast Cancer.

BACKGROUND: The germline variant rs1047303 (HSD3B1[1245A/C]), restricting or enabling production of potent androgens and estrogens from adrenal precursors, affects outcomes of castration-resistant prostate cancer and is associated with estrogen receptor positivity in postmenopausal breast cancer. Like breast cancer, endometrial cancer is another malignancy with hormone-dependent and hormone-independent subtypes. We hypothesized that adrenal-restrictive HSD3B1 genotype would associate with hormone-independent cancer subtypes. METHODS: We employed a previously described classification of tumors in The Cancer Genome Atlas into genomic clusters. We determined HSD3B1 genotype frequencies by endometrial cancer genomic cluster and calculated the odds per adrenal-restrictive A allele for the largely hormone-independent copy-number (CN) high subtype vs other subtypes. An equivalent analysis was performed for the genomically similar, hormone-independent basal breast cancer subtype. Last, we performed survival analyses for UK Biobank participants with endometrial cancer by HSD3B1 genotype. All statistical tests were 2-sided. RESULTS: The adrenal-restrictive HSD3B1(1245A) allele was associated with the CN-high endometrial cancer subtype (odds ratio [OR] = 1.63, 95% confidence interval [CI] = 1.14 to 2.32; P = .007). Similarly, HSD3B1(1245A) was associated with the basal breast cancer subtype (OR = 1.54, 95% CI = 1.13 to 2.08; P = .006). In the UK Biobank, endometrial cancer patients homozygous for HSD3B1(1245A) had worse overall (hazard ratio [HR] = 1.39, 95% CI = 1.16 to 1.68; P < .001) and cancer-specific (HR = 1.39, 95% CI = 1.14 to 1.70; P = .001) survival, consistent with the A allele being enriched in the more aggressive CN-high subtype. CONCLUSIONS: These findings suggest roles for adrenal-restrictive vs adrenal-permissive steroidogenesis, by way of rs1047303 genotype, in the development of and/or outcomes from at least 3 commonly hormone-associated types of cancer: prostate, breast, and endometrial.

Association of HSD3B1 Genotype and Clinical Outcomes in Postmenopausal Estrogen-Receptor-Positive Breast Cancer.

BACKGROUND: Homozygous inheritance of a single-nucleotide polymorphism (1245A > C) in HSD3B1 results in an adrenal permissive phenotype of increased adrenal steroid precursor conversion to potent androgens. This is associated with poor outcomes in prostate cancer. We hypothesized that inheritance of the HSD3B1 adrenal permissive genotype would similarly negatively impact breast cancer outcomes. PATIENTS AND METHODS: Germline HSD3B1 was sequenced in 644 postmenopausal women diagnosed between 2004 and 2015 with stage I-III estrogen receptor-positive (ER+), HER2/neu-negative (HER2-) breast cancer enrolled in a population-based study in western Washington. Primary endpoint was distant metastatic recurrence according to genotype. Secondary endpoint was breast cancer-specific survival. Hazard ratios (HR) were calculated using cause-specific Cox regression accounting for competing risks. RESULTS: Adrenal restrictive genotype (homozygous wild type) was most prevalent (47%), followed by heterozygous (44%) and adrenal permissive (9%). There were no significant differences comparing demographic, tumor, or treatment characteristics apart from higher frequency of adrenal permissive genotype among non-Hispanic white participants (p = 0.04). After accounting for competing risks, the cumulative incidence of distant metastatic recurrence (15 events) was significantly higher among participants with adrenal permissive compared with the adrenal restrictive genotype (HR 4.9, 95% CI 1.32-18.4, p = 0.02). The adrenal permissive genotype was also predictive of breast cancer-specific mortality (HR 3.5, 95% CI 1.27-9.59, p = 0.02). CONCLUSIONS: Inheritance of the HSD3B1 adrenal permissive genotype is associated with increased incidence of distant metastasis and higher cause-specific mortality in postmenopausal ER+/HER2- breast cancer. Further research is necessary to understand the effect of excess adrenal androgen metabolism in promoting breast cancer growth and progression.

Role of single nucleotide polymorphisms of the HSD3B1 gene (rs6203 and rs33937873) in the prediction of prostate cancer risk.

3­ß­hydroxysteroid dehydrogenase 1 (HSD3B1) is shown to affect dihydrotestosterone level in prostatic tissue which is a risk factor for prostate cancer (PC). The present study aimed to determine whether rs33937873 (G313A) and rs6203 (C338T) single nucleotide polymorphisms (SNP) in HSD3B1 gene was a potential risk factor for PC susceptibility and can predict the recurrence of PC in Egyptian patients. A total of 186 Egyptian patients were selected with incident primary PC and compared with 180 age healthy controls. The frequencies and the main effect of rs33937873 and rs6203 in HSD3B1 were compared and investigated between the patients and control using genotyping technique and statistical analysis. The mutant GA genotype of G313A in rs33937873 SNP was considered as an independent risk for PC in the multivariate regression analysis [odds ratio (OR)=2.7, 95% confidence intervals (CI): 1.2­5.5, P=0.01] together with positive history of hypertension (HTN) (OR=6.2, 95% CI: 3.2­12.1, P=0.0001) and begin prostatic hyperplasia (BPH; OR=8.9, 95% CI: 4.5­17.5, P=0.0001). Conversely, in rs6203 (C338T), C allele is considered as major risk allele in the development of PC (OR=1.8, 95% CI: 1.3­2.4, P=0.0003). The univariate logistic regression analyses indicated that CC genotype of rs6203 was a PC risk factor (OR=1.9, 95% CI: 1.3­2.9, P=0.002). In addition, the frequency of the A­C haplotype established by rs33937873­rs6203 was also significantly higher for PC (P=0.013). The predication of PC recurrence was associated only with positive family history (OR=7.7, 95% CI: 2.3­25.9, P=0.001) and not for The G313A and C338T SNPs. These results suggested that the two HSD3B1 polymorphisms rs33937873 and rs6203 may modify the risk of PC, particularly among patients with HTN and history of BPH, suggesting them as prominent future markers for prediction of PC risk.

Inheritance of a common androgen synthesis variant allele is associated with female COVID susceptibility in UK Biobank.

Context: A sex discordance in COVID exists, with males disproportionately affected. Although sex steroids may play a role in this discordance, no definitive genetic data exist to support androgen-mediated immune suppression neither for viral susceptibility nor for adrenally produced androgens. Objective: The common adrenal-permissive missense-encoding variant HSD3B1(1245C) that enables androgen synthesis from adrenal precursors and that has been linked to suppression of inflammation in severe asthma was investigated in COVID susceptibility and outcomes reported in the UK Biobank. Methods: The UK Biobank is a long-term study with detailed medical information and health outcomes for over 500 000 genotyped individuals. We obtained COVID test results, inpatient hospital records, and death records and tested for associations between COVID susceptibility or outcomes and HSD3B1(1245A/C) genotype. Primary analyses were performed on the UK Biobank Caucasian cohort. The outcomes were identification as a COVID case among all subjects, COVID positivity among COVID-tested subjects, and mortality among subjects identified as COVID cases. Results: Adrenal-permissive HSD3B1(1245C) genotype was associated with identification as a COVID case (odds ratio (OR): 1.11 per C allele, 95% CI: 1.04-1.18, P = 0.0013) and COVID-test positivity (OR: 1.09, 95% CI: 1.02-1.17, P = 0.011) in older (≥70 years of age) women. In women identified as COVID cases, there was a positive linear relationship between age and 1245C allele frequency (P < 0.0001). No associations were found between genotype and mortality or between genotype and circulating sex hormone levels. Conclusion: Our study suggests that a common androgen synthesis variant regulates immune susceptibility to COVID infection in women, with increasingly strong effects as women age.

Letrozole protects against cadmium-induced inhibition of spermatogenesis via LHCGR and Hsd3b6 to activate testosterone synthesis in mice.

The heavy metal cadmium is proposed to be one of the environmental endocrine disruptors of spermatogenesis. Cadmium-induced inhibition of spermatogenesis is associated with a hormone secretion disorder. Letrozole is an aromatase inhibitor that increases peripheral androgen levels and stimulates spermatogenesis. However, the potential protective effects of letrozole on cadmium-induced reproductive toxicity remain to be elucidated. In this study, male mice were administered CdCl2 (4 mg/kg BW) orally by gavage alone or in combination with letrozole (0.25 mg/kg BW) for 30 days. Cd exposure caused a significant decreases in body weight, sperm count, motility, vitality, and plasma testosterone levels. Histopathological changes revealed extensive vacuolization and decreased spermatozoa in the lumen. However, in the Cd + letrozole group, letrozole treatment compensated for deficits in sperm parameters (count, motility, and vitality) induced by Cd. Letrozole treatment significantly increased serum testosterone levels, which were reduced by Cd. Histopathological studies revealed a systematic array of all germ cells, a preserved basement membrane and relatively less vacuolization. For a mechanistic examination, RNA-seq was used to profile alterations in gene expression in response to letrozole. Compared with that in the Cd-treated group, RNA-Seq analysis showed that 214 genes were differentially expressed in the presence of letrozole. Gene ontology (GO) enrichment analysis and KEGG signaling pathway analysis showed that steroid biosynthetic processes were the processes most affected by letrozole treatment. Furthermore, we found that the expression of the testosterone synthesis-related genes LHCGR (luteinizing hormone/choriogonadotropin receptor) and Hsd3b6 (3 beta- and steroid delta-isomerase 6) was significantly downregulated in Cd-treated testes, but these genes maintained similar expression levels in letrozole-treated testes as those in the control group. However, the transcription levels of inflammatory cytokines, such as IL-1ß and IL-6, and oxidative stress-related genes (Nrf2, Nqo1, and Ho-1) showed no changes. The present study suggests that the potential protective effect of letrozole on Cd-induced reproductive toxicity might be mediated by the upregulation of LHCGR and Hsd3b6, which would beneficially increase testosterone synthesis to achieve optimum protection of sperm quality and spermatogenesis.

Retrotransposition disrupting EBP in a girl and her mother with X-linked dominant chondrodysplasia punctata.

X-linked dominant chondrodysplasia punctata (CDPX2) is a rare congenital disorder caused by pathogenic variants in EBP on Xp11.23. We encountered a girl and her mother with CDPX2-compatible phenotypes including punctiform calcification in the neonatal period of the girl, and asymmetric limb shortening and ichthyosis following the Blaschko lines in both subjects. Although Sanger direct sequencing failed to reveal a disease-causing variant in EBP, whole genome sequencing (WGS) followed by Manta analysis identified a ~ 4.5 kb insertion at EBP exon 2 of both subjects. The insertion was associated with the hallmarks of retrotransposition such as an antisense poly(A) tail, a target site duplication, and a consensus endonuclease cleavage site, and the inserted sequence harbored full-length SVA_F1 element with 5'- and 3'-transductions containing the Alu sequence. The results imply the relevance of retrotransposition to the human genetic diseases and the usefulness of WGS in the identification of retrotransposition.

Bizarre Chorionic-type Trophoblast in Second-trimester and Third-trimester Placentas: Clinicopathologic Characterization of a Placental Pseudoneoplastic Lesion.

Bizarre (atypical/symplastic) cells have been described in various gynecologic normal tissues and benign neoplasms. This type of bizarre cytologic change is usually an incidental finding and is regarded as a benign process. We describe 17 cases of bizarre chorionic-type trophoblast in second-trimester and third-trimester placentas that created concern for an underlying/undersampled or incipient intraplacental trophoblastic neoplasm, predominantly found in intervillous trophoblastic islands (11/17), placental septae (6/17), chorionic plate (1/17), and/or the chorion layer of fetal membranes (2/17). The bizarre trophoblastic cells exhibited sheet-like or nested architecture, had a multifocal/patchy distribution, and/or were present as individual cells within hyaline stroma; they were characterized by large nuclei with smudgy chromatin and occasional intranuclear pseudoinclusions. The degree of atypia was classified as mild (0/17), moderate (3/17), or severe (14/17). Mitotic figures and necrosis were not identified. A dual immunohistochemical stain for trophoblast (hydroxyl-delta-5-steroid dehydrogenase) and a proliferation marker (Ki-67), performed in 15 cases, demonstrated 0% to very low proliferative activity within the bizarre trophoblast (0% to 2% [10/15], 3% to 8% [5/15]). Immunohistochemical stains for fumarate hydratase showed intact/retained expression in the bizarre cells in 7 of 7 cases. Clinical follow-up ranged from 1 to 45 months, and all patients were alive and well without subsequent evidence of a gestational trophoblastic or other neoplasms. We conclude that bizarre chorionic-type trophoblast in second-trimester or third-trimester placentas have the potential to mimic an intraplacental trophoblastic neoplasm but are likely a benign degenerative change. This study expands the spectrum of bizarre cells that occur in the gynecologic tract.

Low-dose radiation-induced demethylation of 3ß-HSD participated in the regulation of testosterone content.

The effects of low-dose radiation (LDR, ≤0.1 Gy) on living organisms have been the hot areas of radiation biology but do not reach a definitive conclusion yet. So far, few studies have adequately accounted for the male reproductive system responses to LDR, particularly the regulation of testosterone content. Hence, this study was designed to evaluate the effects of LDR on Leydig cells and testicular tissue, especially the ability to synthesize testosterone. We found that less than 0.2-Gy 60 Co gamma rays did not cause significant changes in the hemogram index and the body weight; also, pathological examination did not find obvious structural alterations in testis, epididymis, and other radiation-sensitive organs. Consistently, the results from in vitro showed that only more than 0.5-Gy gamma rays could induce remarkable DNA damage, cycle arrest, and apoptosis. Notably, LDR disturbed the contents of testosterone in mice serums and culture supernatants of TM3 cells and dose dependently increased the expression of 3ß-HSD. After cotreatment with trilostane (Tril), the inhibitor of 3ß-HSD, increased testosterone could be partially reversed. Besides, DNA damage repair-related enzymes, including DNMT1, DNMT3B, and Sirt1, were increased in irradiated TM3 cells, accompanying by evident demethylation in the gene body of 3ß-HSD. In conclusion, our results strongly suggest that LDR could induce obvious perturbation in the synthesis of testosterone without causing organic damage, during which DNA demethylation modification of 3ß-HSD might play a crucial role and would be a potential target to prevent LDR-induced male reproductive damage.

Adrenal-permissive HSD3B1 genetic inheritance and risk of estrogen-driven postmenopausal breast cancer.

BACKGROUNDGenetics of estrogen synthesis and breast cancer risk has been elusive. The 1245A→C missense-encoding polymorphism in HSD3B1, which is common in White populations, is functionally adrenal permissive and increases synthesis of the aromatase substrate androstenedione. We hypothesized that homozygous inheritance of the adrenal-permissive HSD3B1(1245C) is associated with postmenopausal estrogen receptor-positive (ER-positive) breast cancer.METHODSA prospective study of postmenopausal ER-driven breast cancer was done for determination of HSD3B1 and circulating steroids. Validation was performed in 2 other cohorts. Adrenal-permissive genotype frequency was compared between postmenopausal ER-positive breast cancer, the general population, and postmenopausal ER-negative breast cancer.RESULTSProspective and validation studies had 157 and 538 patients, respectively, for the primary analysis of genotype frequency by ER status in White female breast cancer patients who were postmenopausal at diagnosis. The adrenal-permissive genotype frequency in postmenopausal White women with estrogen-driven breast cancer in the prospective cohort was 17.5% (21/120) compared with 5.4% (2/37) for ER-negative breast cancer (P = 0.108) and 9.6% (429/4451) in the general population (P = 0.0077). Adrenal-permissive genotype frequency for estrogen-driven postmenopausal breast cancer was validated using Cambridge and The Cancer Genome Atlas data sets: 14.4% (56/389) compared with 6.0% (9/149) for ER-negative breast cancer (P = 0.007) and the general population (P = 0.005). Circulating androstenedione concentration was higher with the adrenal-permissive genotype (P = 0.03).CONCLUSIONAdrenal-permissive genotype is associated with estrogen-driven postmenopausal breast cancer. These findings link genetic inheritance of endogenous estrogen exposure to estrogen-driven breast cancer.FUNDINGNational Cancer Institute, NIH (R01CA236780, R01CA172382, and P30-CA008748); and Prostate Cancer Foundation Challenge Award.

Trilostane, a 3ß-hydroxysteroid dehydrogenase inhibitor, suppresses growth of hepatocellular carcinoma and enhances anti-cancer effects of sorafenib.

Background Human 3ß-hydroxysteroid dehydrogenase type 1 (HSD3B1) is an enzyme associated with steroidogenesis, however its' role in hepatocellular carcinoma (HCC) biology is unknown. Trilostane is an inhibitor of HSD3B1 and has been tested as a treatment for patients with breast cancer but has not been studied in patients with HCC. Methods and Results The expression of HSD3B1 in HCC tumors in 57 patients were examined. A total of 44 out of 57 tumors (77.2%) showed increased HSD3B1 expression. The increased HSD3B1 in tumors was significantly associated with advanced HCC. In vitro, the knockdown of HSD3B1 expression in Mahlavu HCC cells by a short hairpin RNA (shRNA) led to significant decreases in colony formation and cell migration. The suppression of clonogenicity in the HSD3B1-knockdown HCC cells was reversed by testosterone and 17ß-estradiol. Trilostane-mediated inhibition of HSD3B1 in different HCC cells also caused significant inhibition of clonogenicity and cell migration. In subcutaneous HCC Mahlavu xenografts, trilostane (30 or 60 mg/kg, intraperitoneal injection) significantly inhibited tumor growth in a dose-dependent manner. Furthermore, the combination of trilostane and sorafenib significantly enhanced the inhibition of clonogenicity and xenograft growth, surpassing the effects of each drug used alone, with no documented additional toxicity to animals. HSD3B1 blockade was found to suppress the phosphorylation of extracellular signal-regulated kinase (ERK). The decreased ERK phosphorylation was reversed by testosterone or 17b-estradiol. Conclusions Trilostane significantly inhibited the growth of HCC by inhibiting HSD3B1 function and augmenting the efficacy of sorafenib.

Structural characterization and Kemp eliminase activity of the Mycobacterium smegmatis Ketosteroid Isomerase.

The Kemp elimination reaction, involving the ring-opening of benzoxazole and its derivatives under the action of natural enzymes or chemical catalysts, has been of interest to researchers since its discovery. Because this reaction does not exist in all currently known metabolic pathways, the computational design of Kemp eliminases has provided valuable insights into principles of enzymatic catalysis. However, it was discovered that the naturally occurring promiscuous enzymes ydbC, xapA and ketosteroid isomerase also can catalyze Kemp elimination. Here, we report the crystal structure of ketosteroid isomerase (KSI) from Mycobacterium smegmatis MC2 155. MsKSI crystallizes in the P212121 space group with two molecules in an asymmetric unit, and ultracentrifugation data confirms that it forms a stable dimer in solution, consistent with the 1.9 Å-resolution structure. Our assays confirm that MsKSI accelerates the Kemp elimination of 5-nitrobenzoxazole (5NBI) with an optimal pH of 5.5. A 2.35 Å resolution crystal structure of the MsKSI-5NBI complex reveals that the substrate 5NBI is bound in the active pocket of the enzyme composed of hydrophobic residues. In addition, the Glu127 residue is proposed to play an important role as a general base in proton transfer and breaking weak O-N bonds to open the five-membered ring. This work provides a starting point for exploring the artificial modification of MsKSI using the natural enzyme as the backbone.

A Testis-Specific Long Noncoding RNA, Start, Is a Regulator of Steroidogenesis in Mouse Leydig Cells.

The testis expresses many long noncoding RNAs (lncRNAs), but their functions and overview of lncRNA variety are not well understood. The mouse Prss/Tessp locus contains six serine protease genes and two lncRNAs that have been suggested to play important roles in spermatogenesis. Here, we found a novel testis-specific lncRNA, Start (Steroidogenesis activating lncRNA in testis), in this locus. Start is 1822 nucleotides in length and was found to be localized mostly in the cytosol of germ cells and Leydig cells, although nuclear localization was also observed. Start-knockout (KO) mice generated by the CRISPR/Cas9 system were fertile and showed no morphological abnormality in adults. However, in adult Start-KO testes, RNA-seq and qRT-PCR analyses revealed an increase in the expression of steroidogenic genes such as Star and Hsd3b1, while ELISA analysis revealed that the testosterone levels in serum and testis were significantly low. Interestingly, at 8 days postpartum, both steroidogenic gene expression and testosterone level were decreased in Start-KO mice. Since overexpression of Start in two Leydig-derived cell lines resulted in elevation of the expression of steroidogenic genes including Star and Hsd3b1, Start is likely to be involved in their upregulation. The increase in expression of steroidogenic genes in adult Start-KO testes might be caused by a secondary effect via the androgen receptor autocrine pathway or the hypothalamus-pituitary-gonadal axis. Additionally, we observed a reduced number of Leydig cells at 8 days postpartum. Collectively, our results strongly suggest that Start is a regulator of steroidogenesis in Leydig cells. The current study provides an insight into the overall picture of the function of testis lncRNAs.

Testicular steroidogenesis is suppressed during experimental autoimmune encephalomyelitis in rats.

Multiple sclerosis (MS) is an autoimmune disease that usually occurs during the reproductive years in both sexes. Many male patients with MS show lower blood testosterone levels, which was also observed in male rats during experimental autoimmune encephalomyelitis (EAE), an animal model of MS. To better understand the causes of decreased testosterone production during EAE, we investigated the expression status of genes and proteins associated with steroidogenesis in the testes. No changes in the number of interstitial cells were observed in EAE animals, but the expression of the insulin-like 3 gene was reduced at the peak of the disease, implying that the Leydig cell functional capacity was affected. Consistent with this finding, the expression of most steroidogenic enzyme genes and proteins was reduced during EAE, including StAR, CYP11A1, CYP17A1 and HSD3B. No signs of testicular inflammation were observed. Recovery of steroidogenesis was observed after injection of hCG, the placental gonadotropin, or buserelin acetate, a gonadotropin-releasing hormone analogue, at the peak of EAE. Together, our results are consistent with the hypothesis that impaired testicular steroidogenesis originates upstream of the testes and that low serum LH is the main cause of decreased testosterone levels during EAE.

The association between missense polymorphisms in SRD5A2 and HSD3B1 and treatment failure with abiraterone for castration-resistant prostate cancer.

Missense polymorphism in HSD3B1, encoding 3ß-hydroxysteroid dehydrogenase-1, was associated with outcome after abiraterone treatment. Other androgen-metabolizing enzymes may be involved in therapeutic effect in abiraterone. In this study, we investigated the significance of polymorphisms in genes involved in androgen and abiraterone metabolisms in prostate cancer patients treated with abiraterone. A total of 99 Japanese male castration-resistant prostate cancer patients treated with abiraterone between 2014 and 2018 were included. Genomic DNA was obtained from whole blood samples, and genotyping on SRD5A2 (rs523349), CYP17A1 (rs743572), CYP17A1 (rs2486758), and AKR1C3 (rs12529) was performed by PCR-based technique. Among the 99 patients, 32 (32.3%), 49 (49.5%), and 18 patients (18.2%) carried GG, GC, and CC alleles in SRD5A2, respectively. CC allele was associated with lower risk of treatment failure (hazard ratio, 0.43; 95% confidence interval, 0.20-0.87; P = 0.017) on multivariate analyses, compared with GG/GC alleles. In the combination model using HSD3B1 and SRD5A2 polymorphisms, compared with the combination of AA in HSD3B1 and GG/GC in SRD5A2, other combinations were associated with lower risk of treatment failure (hazard ratio, 0.34; 95% confidence interval, 0.17-0.62; P = 0.0003) on multivariate analyses. This study showed that SRD5A2 genetic variation was associated with the risk of treatment failure in abiraterone. Combinational use of genetic variation in HSD3B1 with SRD5A2 genetic variation augmented the ability of prognostic stratification.