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Werner Kloas - One of the best experts on this subject based on the ideXlab platform.
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mate calling behavior of male south african clawed frogs xenopus laevis is suppressed by the antiandrogenic endocrine disrupting compound flutamide
General and Comparative Endocrinology, 2010Co-Authors: Thomas Behrends, Ralph Urbatzka, Sven Krackow, Andreas Elepfandt, Werner KloasAbstract:Several environmental pollutants have been identified as antiandrogenic endocrine disrupting chemicals (EDC), with flutamide (FLU) being a model compound for this type of action. Despite impacts of EDC interfering with sexual differentiation and reproduction in amphibians, established information about suggested effects on sexual behavior is still lacking. In this study adult male Xenopus laevis were injected with human chorionic gonadotropin (hCG) to initiate mate calling behavior. After one day hCG-stimulated frogs were treated via aqueous exposure over three days without and with FLU at concentrations of 10 8 and 10 6 M in comparison to untreated frogs. Androgen controlled mate calling behavior was recorded during the 12 h dark period. At the end of exposure circulating levels of testosterone (T) and 17b-estradiol (E2) were determined and furthermore gene expression was measured concerning reproductive biomarkers such as hypophysial luteinizing hormone (LH), follicle-stimulating hormone (FSH), testicular aromatase (ARO), 5a reductase type 1 (SRD5A1) and 5a reductase type 2 (SRD5a2). Both concentrations of FLU caused a significant decrease in calling activity starting at the second day of exposure. HCG injected positive controls had elevated levels of T compared to negative control frogs while in parallel treatment with FLU did not affect significantly the hCG elevated sex steroid levels. Furthermore, hCG treatment led to significantly decreased levels of gene expression for ARO and SRD5a2 but no impacts were detected on LH, FSH or SRD5A1 mRNA levels compared to negative controls. In summary, the behavioral parameter mate calling is the most sensitive biomarker detecting antiandrogenic modes of action in this challenge-experiment indicating that this non-invasive method could markedly contribute for sensitive assessment of antiandrogenic EDC.
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aromatase steroid 5 alpha reductase type 1 and type 2 mrna expression in gonads and in brain of xenopus laevis during ontogeny
General and Comparative Endocrinology, 2007Co-Authors: Ralph Urbatzka, Werner Kloas, Ilka LutzAbstract:Abstract The key enzymes involved in the production of endogenous sex steroids are steroid-5-alpha-reductase and aromatase converting testosterone (T) into dihydrotestosterone (DHT) and into estradiol (E2), respectively. To gain more insights into the molecular mechanisms of sexual differentiation of amphibians, we determined the mRNA expression of steroid-5-alpha-reductase type1 (SRD5A1), type2 (Srd5a2) and aromatase (Aro) during ontogeny starting from the egg and ending after completion of metamorphosis in Xenopus laevis . Expression of all three enzymes was measured by means of semi-quantitative RT-PCR, determining for the first time SRD5A1 and Srd5a2 mRNA expression in amphibians. mRNA was analyzed in whole body homogenates from stage 12 to 48, while brain and gonads with kidney were studied separately from stage 48 to 66. Different ontogenetic mRNA expression patterns were observed for all genes analyzed, revealing early mRNA expression of SRD5A1 already in the egg at stage 12 whereas Srd5a2 and Aro was detected at stage 39. Sex-specific mRNA expressions of Srd5a2 and of Aro were determined in the gonads with kidney but not in brain. Srd5a2 was two-fold higher expressed in testes than in ovaries while Aro mRNA was ten-fold higher in ovaries. No gender-specific mRNA expression was observed for SRD5A1 in gonads and in brain. The ontogenetic patterns of Aro, SRD5A1 and Srd5a2 suggest that these genes are involved in sexual differentiation of gonads and brain already in early developmental stages. Especially in gonads Srd5a2 seems to be important for physiological regulation of testis development while Aro is associated with the development of ovaries.
Chantal Guillemette - One of the best experts on this subject based on the ideXlab platform.
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importance of 5α reductase gene polymorphisms on circulating and intraprostatic androgens in prostate cancer
Clinical Cancer Research, 2014Co-Authors: Eric Levesque, Veronique Turcotte, Isabelle Laverdiere, Yves Frade, Melanie Rouleau, Ernard Tetu, Louis Lacombe, Chantal GuillemetteAbstract:Purpose: Polymorphisms in the genes SRD5A1 and SRD5A2 encoding androgen biosynthetic 5α-reductase enzymes have been associated with an altered risk of biochemical recurrence after radical prostatectomy in localized prostate cancer. Experimental Design: To gain potential insights into SRD5A biologic effects, we examined the relationship between SRD5A prognostic markers and endogenous sex-steroid levels measured by mass spectrometry in plasma samples and corresponding prostatic tissues of patients with prostate cancer. Results: We report that five of the seven SRD5A markers differentially affect sex-steroid profiles of dihydrotestosterone and its metabolites in both the circulation and prostatic tissues of patients with prostate cancer. Remarkably, a 32% increase in intraprostatic testosterone levels was observed in the presence of the high-risk SRD5A rs2208532 polymorphism. Moreover, SRD5A2 markers were associated predominantly with circulating levels of inactive glucuronides. Indeed, the rs12470143 SRD5A2 protective allele was associated with high circulating androstane-3α, 17β-diol-17-glucuronide (3α-diol-17G) levels as opposed to lower levels of both 3α-diol-17G and androsterone-glucuronide observed with the rs2208532 SRD5A2 risk allele. Moreover, SRD5A2 rs676033 and rs523349 (V89L) risk variants, in strong linkage disequilibrium, were associated with higher circulating levels of 3α-diol-3G. The SRD5A2 rs676033 variant further correlated with enhanced intraprostatic exposure to 5α-reduced steroids (dihydrotestosterone and its metabolite 3β-diol). Similarly, the SRD5A1 rs166050C risk variant was associated with greater prostatic exposure to androsterone, whereas no association was noted with circulating steroids. Conclusions: Our data support the association of 5α-reductase germline polymorphisms with the hormonal milieu in patients with prostate cancer. Further studies are needed to evaluate if these variants influence 5α-reductase inhibitor efficacy. Clin Cancer Res; 20(3); 576–84. ©2013 AACR .
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molecular markers in key steroidogenic pathways circulating steroid levels and prostate cancer progression
Clinical Cancer Research, 2013Co-Authors: Eric Levesque, Etienne Audetwalsh, Isabelle Laverdiere, Yves Frade, Melanie Rouleau, Shupi Huang, Chaoyua Huang, Louis Lacombe, Chantal GuillemetteAbstract:Purpose: Prostate cancer is a heterogeneous genetic disease, and molecular methods for predicting prognosis in patients with aggressive form of the disease are urgently needed to better personalize treatment approaches. The objective was to identify host genetic variations in candidate steroidogenic genes affecting hormone levels and prostate cancer progression. Experimental Design: The study examined two independent cohorts composed of 526 Caucasian men with organ-confined prostate cancer and 601 Taiwanese men on androgen–deprivation therapy. Caucasians were genotyped for 109 haplotype-tagging single-nucleotide polymorphisms (SNP) in CYP17A1 , ESR1 , CYP19A1 , and HSD3B1 , and their prognostic significance on disease progression was assessed using Kaplan–Meier survival curves and Cox regression models. Positive findings, including previously identified SRD5A1 , SRD5A2 , HSD17B2 , HSD17B3 , and HSD17B12 polymorphisms, were then explored in Taiwanese men ( n = 32 SNPs). The influence of positive markers on the circulating hormonal levels was then appraised in Caucasians using specific and sensitive mass spectrometry–based methods. Results: After adjusting for known risk factors, variants of CYP17A1 (rs6162), HSD17B2 (rs4243229 and rs7201637), and ESR1 (rs1062577) were associated with progressive disease in both cohorts. Indeed, the presence of these variations was significantly associated with progression in Caucasians (HR, 2.29–4.10; P = 0.0014–2 × 10 −7 ) and survival in Taiwanese patients [HR = 3.74; 95% confidence interval (CI): 1.71–8.19, P = 0.009]. Remarkably, the CYP17A1 rs6162 polymorphism was linked to plasma dehydroepiandrosterone-sulfate (DHEA-S) levels ( P = 0.03), HSD17B2 rs7201637 with levels of dihydrotestosterone ( P = 0.03), and ESR1 rs1062577 with levels of estrone-S and androsterone-glucuronide ( P ≤ 0.05). Conclusion: This study identifies, in different ethnic groups and at different disease stages, CYP17A1 , HSD17B2 , and ESR1 as attractive prognostic molecular markers of prostate cancer progression. Clin Cancer Res; 19(3); 699–709. ©2012 AACR .
Etienne Audetwalsh - One of the best experts on this subject based on the ideXlab platform.
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inverse regulation of dht synthesis enzymes 5α reductase types 1 and 2 by the androgen receptor in prostate cancer
Endocrinology, 2017Co-Authors: Etienne Audetwalsh, Tracey Yee, Ingrid S Tam, Vincent GiguereAbstract:5α-Reductase types 1 and 2, encoded by SRD5A1 and SRD5A2, are the two enzymes that can catalyze the conversion of testosterone to dihydrotestosterone, the most potent androgen receptor (AR) agonist in prostate cells. 5α-Reductase type 2 is the predominant isoform expressed in the normal prostate. However, its expression decreases during prostate cancer (PCa) progression, whereas SRD5A1 increases, and the mechanism underlying this transcriptional regulatory switch is still unknown. Interrogation of SRD5A messenger RNA expression in three publicly available data sets confirmed that SRD5A1 is increased in primary and metastatic PCa compared with nontumoral prostate tissues, whereas SRD5A2 is decreased. Activation of AR, a major oncogenic driver of PCa, induced the expression of SRD5A1 from twofold to fourfold in three androgen-responsive PCa cell lines. In contrast, AR repressed SRD5A2 expression in this context. Chromatin-immunoprecipitation studies established that AR is recruited to both SRD5A1 and SRD5A2 genes following androgen stimulation but initiates transcriptional activation only at SRD5A1 as monitored by recruitment of RNA polymerase II and the presence of the H3K27Ac histone mark. Furthermore, we showed that the antiandrogens bicalutamide and enzalutamide block the AR-mediated regulation of both SRD5A1 and SRD5A2, highlighting an additional mechanism explaining their beneficial effects in patients. In summary, we identified an AR-dependent transcriptional regulation that explains the differential expression of 5α-reductase types 1 and 2 during PCa progression. Our work thus defines a mechanism by which androgens control their own synthesis via differential regulatory control of the expression of SRD5A1 and SRD5A2.
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molecular markers in key steroidogenic pathways circulating steroid levels and prostate cancer progression
Clinical Cancer Research, 2013Co-Authors: Eric Levesque, Etienne Audetwalsh, Isabelle Laverdiere, Yves Frade, Melanie Rouleau, Shupi Huang, Chaoyua Huang, Louis Lacombe, Chantal GuillemetteAbstract:Purpose: Prostate cancer is a heterogeneous genetic disease, and molecular methods for predicting prognosis in patients with aggressive form of the disease are urgently needed to better personalize treatment approaches. The objective was to identify host genetic variations in candidate steroidogenic genes affecting hormone levels and prostate cancer progression. Experimental Design: The study examined two independent cohorts composed of 526 Caucasian men with organ-confined prostate cancer and 601 Taiwanese men on androgen–deprivation therapy. Caucasians were genotyped for 109 haplotype-tagging single-nucleotide polymorphisms (SNP) in CYP17A1 , ESR1 , CYP19A1 , and HSD3B1 , and their prognostic significance on disease progression was assessed using Kaplan–Meier survival curves and Cox regression models. Positive findings, including previously identified SRD5A1 , SRD5A2 , HSD17B2 , HSD17B3 , and HSD17B12 polymorphisms, were then explored in Taiwanese men ( n = 32 SNPs). The influence of positive markers on the circulating hormonal levels was then appraised in Caucasians using specific and sensitive mass spectrometry–based methods. Results: After adjusting for known risk factors, variants of CYP17A1 (rs6162), HSD17B2 (rs4243229 and rs7201637), and ESR1 (rs1062577) were associated with progressive disease in both cohorts. Indeed, the presence of these variations was significantly associated with progression in Caucasians (HR, 2.29–4.10; P = 0.0014–2 × 10 −7 ) and survival in Taiwanese patients [HR = 3.74; 95% confidence interval (CI): 1.71–8.19, P = 0.009]. Remarkably, the CYP17A1 rs6162 polymorphism was linked to plasma dehydroepiandrosterone-sulfate (DHEA-S) levels ( P = 0.03), HSD17B2 rs7201637 with levels of dihydrotestosterone ( P = 0.03), and ESR1 rs1062577 with levels of estrone-S and androsterone-glucuronide ( P ≤ 0.05). Conclusion: This study identifies, in different ethnic groups and at different disease stages, CYP17A1 , HSD17B2 , and ESR1 as attractive prognostic molecular markers of prostate cancer progression. Clin Cancer Res; 19(3); 699–709. ©2012 AACR .
Bertha Chávez - One of the best experts on this subject based on the ideXlab platform.
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molecular analysis of the srd5a2 in 46 xy subjects with incomplete virilization the p212r substitution of the steroid 5α reductase 2 may constitute an ancestral founder mutation in mexican patients
Journal of Andrology, 2010Co-Authors: Felipe Vilchis, Luis Ramos, Juan Pablo Mendez, Socorro Benavides, Patricia Canto, Bertha ChávezAbstract:: Inactivating mutations of the SRD5A2 gene result in steroid 5α-reductase 2 deficiency, an autosomal recessive disorder expressed as a male-limited disorder of sex development. Herein, genomic DNA was isolated from 11 new patients with apparent steroid 5α-reductase 2 deficiency. Coding sequence abnormalities in SRD5A2 were assessed by exon-specific polymerase chain reaction, single-stranded conformation polymorphism, and direct sequencing. Likewise, enzymatic activity of the P212R gene variant of SRD5A2 was assessed. DNA analysis revealed mutations in all patients (G115D, R171S, N193S, E197D, G203S, P212R). Three individuals were compound heterozygotes, 6 were homozygotes, and 2 more were single heterozygotes for SRD5A2 mutations; remarkably, 40% of the mutant alleles (9/22) contained the gene variant P212R. The results described in this study represent, along with our previous reports, the largest number of patients with steroid 5α-reductase 2 deficiency belonging to nonrelated families. Regarding the frequency of the p.P212R mutation in our population and its presence throughout all of our country, it allows us to hypothesize that the presence of this mutation may constitute a founder gene effect.
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Novel compound heterozygous mutations in the SRD5A2 gene from 46,XY infants with ambiguous external genitalia
Journal of Human Genetics, 2008Co-Authors: Felipe Vilchis, Evangelina Valdez, Rocío García, Luis Ramos, Rita Gómez, Bertha ChávezAbstract:Dihydrotestosterone is crucial for normal development of external genitalia and prostate in the male embryo. Autosomal recessive mutations in the 5α-reductase type 2 (SRD5A2) gene disrupt the synthesis of dihydrotestosterone in the urogenital tract and give rise to genetic males with undervirilized external genitalia that may be female-like or ambiguous. In this study, three unrelated 46,XY children (0.5, 3, and 8 years old) who presented severe undermasculinization at birth were examined for genetic abnormalities in the SRD5A2 gene. Coding sequence abnormalities were ascertained by exon-specific polymerase chain reaction (PCR), single-stranded conformational polymorphism (SSCP), and sequencing analysis. Functional properties of the mutant alleles were investigated by means of site-directed mutagenesis assays. DNA molecular studies showed that all three patients were compound heterozygotes for SRD5A2 mutations. Patient 1 had a point mutation 547G → A in exon 3 (G183S) and a novel dinucleotidic mutation 634,635CC → TG in exon 4 (P212X). This double change results in premature termination signal (TGA) at codon 212, which predicts the expression of a truncated 211-amino acid protein. Patient 2 was the carrier of mutations G115D in exon 3 and S210F in exon 4. Patient 3 had two substitution mutations in exon 1, including a novel G → C transversion at nucleotide 169 (E57Q) and a G → A transition at nucleotide 254 (G85D). In transitory transfection assays, the recombinant cDNAs harboring mutations E57Q and G85D showed residual 5α-reductase activity, whereas those with mutations G115D, S210F, and P212X were devoided of activity. In contrast, the G183S substitution affected the catalytic activity of the enzyme by decreasing its affinity for testosterone substrate. We describe six different mutations of the SRD5A2 gene detected in three children with genital ambiguity. These genotypes are consistent with the clinical phenotype of steroid 5α-reductase 2 deficiency. Our data suggest that the combined gene variants (E57Q/G85D, G115D/S210F, and G183S/P212X) result in subfunctional or nonfunctional enzymes, causing masculinization defects in these patients. This further underscores that exon 4 of SRD5A2 may be a site prone to inactivating mutations.
Martin Holder - One of the best experts on this subject based on the ideXlab platform.
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phenotypic classification of male pseudohermaphroditism due to steroid 5α reductase 2 deficiency
American Journal of Medical Genetics, 1996Co-Authors: Gernot H G Sinnecker, Norbert Albers, Michael Hemminghaus, W Hoepffner, H. Haus, Helmuth G Dorr, Leif Dibbelt, U Heinrich, Olaf Hiort, Martin HolderAbstract:Conversion of testosterone (T) to dihydrotestosterone (DHT) in genital tissue is catalysed by the enzyme 5{alpha}-reductase 2, which is encoded by the SRD5A2 gene. The potent androgen DHT is required for full masculinization of the external genitalia. Mutations of the SRD5A2 gene inhibit enzyme activity, diminish DHT formation, and hence cause masculinization defects of varying degree. The classical syndrome, formerly described as pseudovaginal perineoscrotal hypospadias, is characterized by a predominantly female phenotype at birth and significant virilization without gynecomastia at puberty. We investigated nine patients with steroid 5{alpha}-reductase 2 deficiency (SRD). T/DHT-ratios were highly increased in the classical syndrome, but variable in the less severe affected patients. Mutations in the SRD5A2 gene had been characterized using PCR-SSCP analysis and direct DNA sequencing. A small deletion was encountered in two patients, while all other patients had single base mutations which result in amino acid substitutions. We conclude that phenotypes may vary widely in patients with SRD5A2 gene mutations spanning the whole range from completely female to normal male without distinctive clinical signs of the disease. Hence, steroid 5{alpha}-reductase deficiency should be considered not only in sex reversed patients with female or ambiguous phenotypes, but also in those with mild symptoms ofmore » undermasculinization as encountered in patients with hypospadias and/or micropenis. A classification based on the severity of the masculinization defect may be used for correlation of phenotypes with enzyme activities and genotypes, and for comparisons of phenotypes between different patients as the basis for clinical decisions to be made in patients with pseudohermaphroditism due to steroid 5{alpha}-reductase 2 deficiency. 22 refs., 2 figs., 2 tabs.« less