51
|
Callard GV, Tarrant AM, Novillo A, Yacci P, Ciaccia L, Vajda S, Chuang GY, Kozakov D, Greytak SR, Sawyer S, Hoover C, Cotter KA. Evolutionary origins of the estrogen signaling system: insights from amphioxus. J Steroid Biochem Mol Biol 2011; 127:176-88. [PMID: 21514383 PMCID: PMC3179578 DOI: 10.1016/j.jsbmb.2011.03.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 02/07/2011] [Accepted: 03/25/2011] [Indexed: 11/23/2022]
Abstract
Classically, the estrogen signaling system has two core components: cytochrome P450 aromatase (CYP19), the enzyme complex that catalyzes the rate limiting step in estrogen biosynthesis; and estrogen receptors (ERs), ligand activated transcription factors that interact with the regulatory region of target genes to mediate the biological effects of estrogen. While the importance of estrogens for regulation of reproduction, development and physiology has been well-documented in gnathostome vertebrates, the evolutionary origins of estrogen as a hormone are still unclear. As invertebrates within the phylum Chordata, cephalochordates (e.g., the amphioxus of the genus Branchiostoma) are among the closest invertebrate relatives of the vertebrates and can provide critical insight into the evolution of vertebrate-specific molecules and pathways. To address this question, this paper briefly reviews relevant earlier studies that help to illuminate the history of the aromatase and ER genes, with a particular emphasis on insights from amphioxus and other invertebrates. We then present new analyses of amphioxus aromatase and ER sequence and function, including an in silico model of the amphioxus aromatase protein, and CYP19 gene analysis. CYP19 shares a conserved gene structure with vertebrates (9 coding exons) and moderate sequence conservation (40% amino acid identity with human CYP19). Modeling of the amphioxus aromatase substrate binding site and simulated docking of androstenedione in comparison to the human aromatase shows that the substrate binding site is conserved and predicts that androstenedione could be a substrate for amphioxus CYP19. The amphioxus ER is structurally similar to vertebrate ERs, but differs in sequence and key residues of the ligand binding domain. Consistent with results from other laboratories, amphioxus ER did not bind radiolabeled estradiol, nor did it modulate gene expression on an estrogen-responsive element (ERE) in the presence of estradiol, 4-hydroxytamoxifen, diethylstilbestrol, bisphenol A or genistein. Interestingly, it has been shown that a related gene, the amphioxus "steroid receptor" (SR), can be activated by estrogens and that amphioxus ER can repress this activation. CYP19, ER and SR are all primarily expressed in gonadal tissue, suggesting an ancient paracrine/autocrine signaling role, but it is not yet known how their expression is regulated and, if estrogen is actually synthesized in amphioxus, whether it has a role in mediating any biological effects. Functional studies are clearly needed to link emerging bioinformatics and in vitro molecular biology results with organismal physiology to develop an understanding of the evolution of estrogen signaling. This article is part of a Special Issue entitled 'Marine organisms'.
Collapse
Affiliation(s)
- G V Callard
- Department of Biology, Boston University, 5 Cummington St, Boston, MA 02215, United States.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
52
|
|
53
|
Celander MC, Goldstone JV, Denslow ND, Iguchi T, Kille P, Meyerhoff RD, Smith BA, Hutchinson TH, Wheeler JR. Species extrapolation for the 21st century. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2011; 30:52-63. [PMID: 20963850 DOI: 10.1002/etc.382] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Safety factors are used in ecological risk assessments to extrapolate from the toxic responses of laboratory test species to all species representing that group in the environment. More accurate extrapolation of species responses is important. Advances in understanding the mechanistic basis for toxicological responses and identifying molecular response pathways can provide a basis for extrapolation across species and, in part, an explanation for the variability in whole organism responses to toxicants. We highlight potential short- and medium-term development goals to meet our long-term aspiration of truly predictive in silico extrapolation across wildlife species' response to toxicants. A conceptual approach for considering cross-species extrapolation is presented. Critical information is required to establish evidence-based species extrapolation, including identification of critical molecular pathways and regulatory networks that are linked to the biological mode of action and species' homologies. A case study is presented that examines steroidogenesis inhibition in fish after exposure to fadrozole or prochloraz. Similar effects for each compound among fathead minnow, medaka, and zebrafish were attributed to similar inhibitor pharmacokinetic/pharmacodynamic distributions and sequences of cytochrome P45019A1/2 (CYP19A1/2). Rapid advances in homology modeling allow the prediction of interactions of chemicals with enzymes, for example, CYP19 aromatase, which would eventually allow a prediction of potential aromatase toxicity of new compounds across a range of species. Eventually, predictive models will be developed to extrapolate across species, although substantial research is still required. Knowledge gaps requiring research include defining differences in life histories (e.g., reproductive strategies), understanding tissue-specific gene expression, and defining the role of metabolism on toxic responses and how these collectively affect the power of interspecies extrapolation methods.
Collapse
Affiliation(s)
- Malin C Celander
- University of Gothenburg, Department of Zoology, Göteborg, Sweden.
| | | | | | | | | | | | | | | | | |
Collapse
|
54
|
Gohin M, Bobe J, Chesnel F. Comparative transcriptomic analysis of follicle-enclosed oocyte maturational and developmental competence acquisition in two non-mammalian vertebrates. BMC Genomics 2010; 11:18. [PMID: 20059772 PMCID: PMC2821372 DOI: 10.1186/1471-2164-11-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 01/08/2010] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND In vertebrates, late oogenesis is a key period during which the oocyte acquires its ability to resume meiosis (i.e. maturational competence) and to develop, once fertilized, into a normal embryo (i.e. developmental competence). However, the molecular mechanisms involved in these key biological processes are far from being fully understood. In order to identify key mechanisms conserved among teleosts and amphibians, we performed a comparative analysis using ovarian tissue sampled at successive steps of the maturational competence acquisition process in the rainbow trout (Oncorhynchus mykiss) and in the clawed toad (Xenopus laevis). Our study aimed at identifying common differentially expressed genes during late oogenesis in both species. Using an existing transcriptomic analysis that had previously been carried out in rainbow trout, candidate genes were selected for subsequent quantitative PCR-based comparative analysis. RESULTS Among the 1200 differentially expressed clones in rainbow trout, twenty-six candidate genes were selected for further analysis by real-time PCR in both species during late oogenesis. Among these genes, eight had similar expression profiles in trout and Xenopus. Six genes were down-regulated during oocyte maturation (cyp19a1, cyp17a1, tescalcin, tfr1, cmah, hsd11b3) while two genes exhibited an opposite pattern (apoc1, star). In order to document possibly conserved molecular mechanisms, four genes (star, cyp19a1, cyp17a1 and hsd11b3) were further studied due to their known or suspected role in steroidogenesis after characterization of the orthology relationships between rainbow trout and Xenopus genes. Apoc1 was also selected for further analysis because of its reported function in cholesterol transport, which may modulate steroidogenesis by regulating cholesterol bioavailability in the steroidogenic cells. CONCLUSIONS We have successfully identified orthologous genes exhibiting conserved expression profiles in the ovarian follicle during late oogenesis in both trout and Xenopus. While some identified genes were previously uncharacterized during Xenopus late oogenesis, the nature of these genes has pointed out molecular mechanisms possibly conserved in amphibians and teleosts. It should also be stressed that in addition to the already suspected importance of steroidogenesis in maturational competence acquisition, our approach has shed light on other regulatory pathways which may be involved in maturational and developmental competence acquisitions that will require further studies.
Collapse
Affiliation(s)
- Maella Gohin
- CNRS/IGDR (UMR 6061), IFR140 GFAS, Université de Rennes I, 2, Avenue du Pr, Léon Bernard, 35043 Rennes Cedex, France.
| | | | | |
Collapse
|
55
|
Dufour S, Sebert ME, Weltzien FA, Rousseau K, Pasqualini C. Neuroendocrine control by dopamine of teleost reproduction. JOURNAL OF FISH BIOLOGY 2010; 76:129-160. [PMID: 20738703 DOI: 10.1111/j.1095-8649.2009.02499.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
While gonadotropin-releasing hormone (GnRH) is considered as the major hypothalamic factor controlling pituitary gonadotrophins in mammals and most other vertebrates, its stimulatory actions may be opposed by the potent inhibitory actions of dopamine (DA) in teleosts. This dual neuroendocrine control of reproduction by GnRH and DA has been demonstrated in various, but not all, adult teleosts, where DA participates in an inhibitory role in the neuroendocrine regulation of the last steps of gametogenesis (final oocyte maturation and ovulation in females and spermiation in males). This has major implications for inducing spawning in aquaculture. In addition, DA may also play an inhibitory role during the early steps of gametogenesis in some teleost species, and thus interact with GnRH in the control of puberty. Various neuroanatomical investigations have shown that DA neurones responsible for the inhibitory control of reproduction originate in a specific nucleus of the preoptic area (NPOav) and project directly to the region of the pituitary where gonadotrophic cells are located. Pharmacological studies showed that the inhibitory effects of DA on pituitary gonadotrophin production are mediated by DA-D2 type receptors. DA-D2 receptors have now been sequenced in several teleosts, and the coexistence of several DA-D2 subtypes has been demonstrated in a few species. Hypophysiotropic DA activity varies with development and reproductive cycle and probably is controlled by environmental cues as well as endogenous signals. Sex steroids have been shown to regulate dopaminergic systems in several teleost species, affecting both DA synthesis and DA-D2 receptor expression. This demonstrates that sex steroid feedbacks target DA hypophysiotropic system, as well as the other components of the brain-pituitary gonadotrophic axis, GnRH and gonadotrophins. Recent studies have revealed that melatonin modulates the activity of DA systems in some teleosts, making the melatonin-DA pathway a prominent relay between environmental cues and control of reproduction. The recruitment of DA neurons for the neuroendocrine control of reproduction provides an additional brain pathway for the integration of various internal and environmental cues. The plasticity of the DA neuroendocrine role observed in teleosts may have contributed to their large diversity of reproductive cycles.
Collapse
Affiliation(s)
- S Dufour
- Muséum National d'Histoire Naturelle, UMR Biologie des Organismes et Ecosystèmes Aquatiques" MNHN-CNRS-IRD-UPMC, 7 rue Cuvier, CP 32, 75231 Paris Cedex 05, France.
| | | | | | | | | |
Collapse
|
56
|
Huang W, Zhou L, Li Z, Gui JF. Expression pattern, cellular localization and promoter activity analysis of ovarian aromatase (Cyp19a1a) in protogynous hermaphrodite red-spotted grouper. Mol Cell Endocrinol 2009; 307:224-36. [PMID: 19443102 DOI: 10.1016/j.mce.2009.04.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Revised: 04/05/2009] [Accepted: 04/06/2009] [Indexed: 11/30/2022]
Abstract
Aromatase plays a key role in sex differentiation of gonads. In this study, we cloned the full-length cDNA of ovarian aromatase from protogynous hermaphrodite red-spotted grouper (Epinephelus akaara), and prepared the corresponding anti-EaCyp19a1a antiserum. Western blot and immunofluorescence studies revealed ovary-specific expression pattern of EaCyp19a1a in adults and its dynamic expression change during artificial sex reversal. EaCyp19a1a was expressed by follicular cells of follicular layer around oocytes because strong EaCyp19a1a immunofluorescence was observed in the cells of ovaries. During artificial sex reversal, EaCyp19a1a expression dropped significantly from female to male, and almost no any positive EaCyp19a1a signal was observed in testicular tissues. Then, we cloned and sequenced a total of 1967 bp 5'-flanking sequence of EaCyp19a1a promoter, and showed a number of potential binding sites for some transcriptional factors, such as SOX5, GATA gene family, CREB, AP1, FOXL1, C/EBP, ARE and SF-1. Moreover, we prepared a series of 5' deletion promoter constructs and performed in vitro luciferase assays of EaCyp19a1a promoter activities. The data indicated that the CREB regulation region from -1010 to -898 might be a major cis-acting element to EaCyp19a1a promoter, whereas the elements GATA and SOX5 in the region from -1216 to -1010 might be suppression elements. Significantly, we found a common conserved sequence region in the fish ovary-type aromatase promoters with identities from 93% to 34%. And, the motifs of TATA box, SF-1, SOX5, and CREB existed in the region and were conserved among the most of fish species.
Collapse
Affiliation(s)
- Wei Huang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Wuhan, China
| | | | | | | |
Collapse
|
57
|
Liu JF, Guiguen Y, Liu SJ. Aromatase (P450arom) and 11beta-hydroxylase (P45011beta) genes are differentially expressed during the sex change process of the protogynous rice field eel, Monopterus albus. FISH PHYSIOLOGY AND BIOCHEMISTRY 2009; 35:511-518. [PMID: 18807204 DOI: 10.1007/s10695-008-9255-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 07/27/2008] [Indexed: 05/26/2023]
Abstract
Steroids are known to play a crucial role in gonadal sex differentiation in many non-mammalian vertebrates, but also in the gonadal sex change of hermaphroditic teleosts. We investigated the expression of two genes encoding key steroidogenic enzymes, i.e., cytochrome P450 aromatase (P450arom) and cytochrome P45011beta-hydroxylase (P45011beta), during the sex change of the protogynous rice field eel, Monopterus albus. Using RT-PCR with degenerate primers, we cloned rice field eel homologous fragments for both genes (rcP450arom and rcP45011beta) as indicated by the high level of homology with P450arom and P45011beta sequences from various vertebrates. Gonadal expression of rcP450arom and rcP45011beta mRNA levels were then assessed during the sex change by semi-quantitative RT-PCR and a real-time RT-PCR. rcP450arom was predominantly expressed in ovary, much less in ovotestis, and barely in testis. Conversely, P45011beta was markedly up-regulated at the onset of testicular development. These findings underline that regulation of steroidogenesis is an important process in the sex change of protogynous rice field eel, and they clearly indicate that the concomitant down-regulation of P450arom and up-regulation of P45011beta are of pivotal importance to the sex change of this species.
Collapse
Affiliation(s)
- Ji-Fang Liu
- Key Laboratory of Protein Chemistry and Fish Developmental Biology of State Education Ministry of China, College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, People's Republic of China
| | | | | |
Collapse
|
58
|
Conley AJ, Corbin CJ, Hughes AL. Adaptive evolution of mammalian aromatases: lessons from Suiformes. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL GENETICS AND PHYSIOLOGY 2009; 311:346-57. [PMID: 18381772 PMCID: PMC2693275 DOI: 10.1002/jez.451] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Estrogen synthesis evolved in chordates to control reproduction. The terminal enzyme in the cascade directly responsible for estrogen synthesis is aromatase cytochrome P450 (P450arom) encoded by the CYP19 gene. Mammals typically have a single CYP19 gene but pigs, peccaries and other Suiformes have two or more resulting from duplication in a common ancestor. Duplication of CYP genes in the steroid synthetic cascade has occurred for only one other enzyme, also terminal, 11beta-hydroxylase P450 (P450c11). P450arom and P450c11 share common substrates and even physiological functions as possible remnants from a common P450 progenitor, perhaps an ancestral P450arom, which is supported by phylogenetic analysis. Conserved tissue-specific expression patterns of P450arom paralogs in placenta and gonads of pigs and peccaries suggest how functional adaptation may have proceeded divergently and influenced adopted reproductive strategies including ovulation rate and litter size. Data suggest that the porcine placental paralog evolved catalytically to protect female conceptuses from testosterone produced by male siblings; the gonadal paralog to synthesize a novel, nonaromatizable testosterone metabolite (1OH-testosterone) that may increase ovulation rate. This would represent a coevolution facilitating litter bearing as pigs diverged from peccaries. Evidence of convergence between the peccary CYP19 genes and lower tissue expression may therefore represent initiation of loss of the functional paralogs. Studies on the Suiforme aromatases provide insights into the evolution of the steroidogenic cascade and metabolic pathways in general, how it translates into physiological adaptations (altered reproductive strategies for instance), and how duplicated genes become stabilized or disappear from genomes.
Collapse
Affiliation(s)
- A J Conley
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
| | | | | |
Collapse
|
59
|
Corbin CJ, Berger T, Ford JJ, Roselli CE, Sienkiewicz W, Trainor BC, Roser JF, Vidal JD, Harada N, Conley AJ. Porcine hypothalamic aromatase cytochrome P450: isoform characterization, sex-dependent activity, regional expression, and regulation by enzyme inhibition in neonatal boars. Biol Reprod 2009; 81:388-95. [PMID: 19403926 DOI: 10.1095/biolreprod.109.076331] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Domestic pigs have three CYP19 genes encoding functional paralogues of the enzyme aromatase cytochrome P450 (P450arom) that are expressed in the gonads, placenta, and preimplantation blastocyst. All catalyze estrogen synthesis, but the gonadal-type enzyme is unique in also synthesizing a nonaromatizable biopotent testosterone metabolite, 1OH-testosterone (1OH-T). P450arom is expressed in the vertebrate brain, is higher in males than females, but has not been investigated in pigs, to our knowledge. Therefore, these studies defined which of the porcine CYP19 genes was expressed, and at what level, in adult male and female hypothalamus. Regional expression was examined in mature boars, and regulation of P450arom expression in neonatal boars was investigated by inhibition of P450arom with letrozole, which is known to reprogram testicular expression. Pig hypothalami expressed the gonadal form of P450arom (redesignated the "gonadal/hypothalamic" porcine CYP19 gene and paralogue) based on functional analysis confirmed by cloning and sequencing transcripts. Hypothalamic tissue synthesized 1OH-T and was sensitive to the selective P450arom inhibitor etomidate. Levels were 4-fold higher in male than female hypothalami, with expression in the medial preoptic area and lateral borders of the ventromedial hypothalamus of boars. In vivo, letrozole-treated neonates had increased aromatase activity in hypothalami but decreased activity in testes. Therefore, although the same CYP19 gene is expressed in both tissues, expression is regulated differently in the hypothalamus than testis. These investigations, the first such studies in pig brain to our knowledge, demonstrate unusual aspects of P450arom expression and regulation in the hypothalamus, offering promise of gaining better insight into roles of P450arom in reproductive function.
Collapse
Affiliation(s)
- C J Corbin
- Department of Population Health & Reproduction, University of California Davis, Davis, California 95616, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
60
|
Kah O, Pellegrini E, Mouriec K, Diotel N, Anglade I, Vaillant C, Thieulant ML, Tong SK, Brion F, Chung BC, Pakdel F. Œstrogènes et neurogenèse : de nouvelles fonctions pour une vieille hormone. Leçons tirées du poisson zèbre. ACTA ACUST UNITED AC 2009; 203:29-38. [PMID: 19358809 DOI: 10.1051/jbio:2009007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Olivier Kah
- Neurogenèse, Aromatase et OEstrogènes, Université de Rennes 1, UMR CNRS 6026, Campus de Beaulieu, 35042 Rennes Cedex, France.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
61
|
Le Page Y, Menuet A, Kah O, Pakdel F. Characterization of a cis-acting element involved in cell-specific expression of the zebrafish brain aromatase gene. Mol Reprod Dev 2008; 75:1549-57. [PMID: 18288647 DOI: 10.1002/mrd.20892] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The cytochrome P450 Aromatase is the key enzyme catalyzing the conversion of androgens into estrogens. In zebrafish, the brain aromatase is encoded by cyp19b. Expression of cyp19b is restricted to radial glial cells bordering forebrain ventricles and is strongly stimulated by estrogens during development. At the promoter level, we have previously shown that an estrogen responsive element (ERE) is required for induction by estrogens. Here, we investigated the role of ERE flanking regions in the control of cell-specific expression. First, we show that a 20 bp length motif, named G x RE (glial x responsive element), acts in synergy with the ERE to mediate the estrogenic induction specifically in glial cells. Second, we demonstrate that, in vitro, this sequence binds factors exclusively present in glial or neuro-glial cells and is able to confer a glial specificity to an artificial estrogen-dependent gene. Taken together, these results contribute to the understanding of the molecular mechanisms allowing cyp19b regulation by estrogens and allowed to identify a promoter sequence involved in the strong estrogen inducibility of cyp19b which is specific for glial cells. The exceptional aromatase activity measured in the brain of teleost fish could rely on such mechanisms.
Collapse
Affiliation(s)
- Yann Le Page
- Université de Rennes 1, UMR CNRS 6026, Interactions Cellulaires et Moléculaires, Rennes, France
| | | | | | | |
Collapse
|
62
|
Chourasia TK, Joy KP. Ovarian P450 aromatase activity in the catfish Heteropneustes fossilis: seasonal changes and effects of catecholestrogens. Gen Comp Endocrinol 2008; 156:537-43. [PMID: 18395205 DOI: 10.1016/j.ygcen.2008.02.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 02/16/2008] [Accepted: 02/29/2008] [Indexed: 11/22/2022]
Abstract
Ovarian microsomal aromatase (P450arom) activity was studied in relation to season and incubation of follicles with catecholestrogens [(2-hydroxyestradiol-17beta (2-OHE2) and 2-methoxyestradiol-17 beta (2-methoxyE2)] using a product (estradiol-17 beta) assay. Peak P450arom activity was noticed in late preparatory phase (April) and it decreased significantly in pre-spawning, spawning and post-spawning phases to give the lowest value in resting phase. Apparent Km and Vmax of the enzyme varied significantly and the values were high in the preparatory (vitellogenic) phase (Km 74.62+/-1.73 nM, Vmax 0.81+/-0.01 pmol/mg protein/min) and low in the spawning (post-vitellogenic) phase (Km 62.01+/-1.68 nM, Vmax 0.69+/-0.002 pmol/mg protein/min). The incubation of the ovarian microsomes with 2-OHE2 elicited significant biphasic effects on enzyme activity. In the vitellogenic phase, concentrations of the steroid up to 1 microM inhibited enzyme activity significantly with the highest inhibition at 10nM. However, in the post-vitellogenic ovary, the highest inhibition was registered at 100 nM. The higher concentrations (10 microM or 100 microM) did not elicit any significant change compared to the control groups. A comparison of the aromatase inhibition index (AI50, indicates 50% inhibition of aromatase activity) of fadrozole, a known aromatase inhibitor and 2-OHE2 shows that the AI50 was 4.4 nM for fadrozole and 0.864 nM (vitellogenic phase) and 1.31 nM (post-vitellogenic phase) for 2-OHE2 indicating higher potency of the latter. The incubation of the ovarian microsomes with 2-methoxyE2 increased enzyme activity only at the higher concentrations (1-100 microM). The results show seasonality in the potential of the ovary to synthesize E2 and the potent enzyme inhibiting activity of 2-OHE2, which is reported for the first time.
Collapse
Affiliation(s)
- T K Chourasia
- Center of Advanced Study, Department of Zoology, Banaras Hindu University, Varanasi, Uttar Pradesh 221005, India
| | | |
Collapse
|
63
|
Lassiter CS, Linney E. Embryonic expression and steroid regulation of brain aromatase cyp19a1b in zebrafish (Danio rerio). Zebrafish 2008; 4:49-57. [PMID: 18041942 DOI: 10.1089/zeb.2006.9995] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Estradiol is produced from testosterone by the aromatase gene, cyp19. In the zebrafish Danio rerio, brain aromatase, cyp19a1b, is highly expressed during development. We report the developmental expression pattern of cyp19a1b using whole mount in situ hybridization and describe hormonal effects on the gene using RT-PCR. Expression is up-regulated between 24 and 48 hours postfertilization (hpf). Localized expression of cyp19a1b is first detected at 48 hpf in the preoptic area, hypothalamus, terminal nerve, and olfactory bulb. The gene is itself induced by estradiol in a positive feedback loop. Testosterone exposure also induces the cyp19a1b gene in zebrafish; however, a majority of this induction is blocked by an estrogen receptor antagonist. The expression pattern of aromatase in the brain and its control by steroid hormones is well conserved among the vertebrate lineage.
Collapse
Affiliation(s)
- Christopher S Lassiter
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA.
| | | |
Collapse
|
64
|
Distinct cytochrome P450 aromatase isoforms in the common carp (Cyprinus carpio): sexual dimorphism and onset of ontogenic expression. Gen Comp Endocrinol 2008; 156:499-508. [PMID: 18430424 DOI: 10.1016/j.ygcen.2008.03.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 03/06/2008] [Accepted: 03/07/2008] [Indexed: 02/02/2023]
Abstract
Cytochrome P450 aromatase (CYP19) is a key enzyme in the steroidogenic pathway that catalyses the conversion of testosterone to estrogen, and therefore is thought to influence gonadal sex differentiation. In an effort to understand the role of this enzyme in ovarian differentiation, we isolated cDNA encoding the two distinct isoforms, ovarian and brain (termed cyp19a and cyp19b, respectively) of adult common carp, Cyprinus carpio. The cloned cDNA for cyp19a had an open reading frame (ORF) of 518 amino acid residues, in contrast to cyp19b with an ORF of 511 amino acids. Sequence and phylogenetic analysis showed that these CYP19 isoforms were orthologous with previously described cyp19a and cyp19b from other teleosts. Quantitative real-time PCR indicated that both isoforms are expressed in adult ovary and brain, with predominant expression of cyp19a in the ovary and cyp19b in the brain. The major aromatase expressing tissue was found to be the brain, with greatest cyp19b expression in the anterior quarter (telencephalon) in both sexes. The gonad showed sexually dimorphic expression of both genes and dimorphic expression of cyp19a was observed in the cerebellum and the liver. Ontogenic expression showed that only the ovarian aromatase transcript is inherited maternally, with lower expression observed through early larval development under warmer rearing conditions. The differential and overlapping expression suggests these two aromatase genes have different roles in reproductive physiology.
Collapse
|
65
|
Yu JH, Tang YK, Li JL. Cloning, Structure, and Expression Pattern of the P-450 Aromatase Gene in Rice Field Eel (Monopterus albus). Biochem Genet 2008; 46:267-80. [DOI: 10.1007/s10528-008-9154-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Revised: 09/16/2007] [Accepted: 09/16/2007] [Indexed: 10/22/2022]
|
66
|
Pellegrini E, Mouriec K, Anglade I, Menuet A, Le Page Y, Gueguen MM, Marmignon MH, Brion F, Pakdel F, Kah O. Identification of aromatase-positive radial glial cells as progenitor cells in the ventricular layer of the forebrain in zebrafish. J Comp Neurol 2007; 501:150-67. [PMID: 17206614 DOI: 10.1002/cne.21222] [Citation(s) in RCA: 224] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Compared with other vertebrates, the brain of adult teleost fish exhibits two unique features: it exhibits unusually high neurogenic activity and strongly expresses aromatase, a key enzyme that converts aromatizable androgens into estrogens. Until now, these two features, high neurogenic and aromatase activities, have never been related to each other. Recently, it was shown that aromatase is expressed in radial glial cells of the forebrain and not in neurons. Here, we further document that Aromatase B is never detected in cells expressing the markers of postmitotic neurons, Hu and acetylated tubulin. By using a combination of bromodeoxyuridine (BrdU) treatment and immunohistochemical techniques, we demonstrate for the first time to our knowledge that aromatase-positive radial cells actively divide to generate newborn cells in many forebrain regions. Such newborn cells can further divide, as shown by BrdU-proliferating cell nuclear antigen double staining. We also demonstrate that, over time, newborn cells move away from the ventricles, most likely by migrating along the radial processes. Finally, by using antisera to Hu and acetylated tubulin, we further document that some of the newborn cells derived from radial glia differentiate into neurons. These data provide new evidence for the mechanism of neurogenesis in the brain of adult fish. In addition, given that estrogens are well-known neurotrophic and neuroprotective factors affecting proliferation, apoptosis, migration, and differentiation, the expression of aromatase in the neural stem cells of the adult strongly demonstrates that the fish brain is an outstanding model for studying the effects of estrogens on adult neurogenesis and brain repair.
Collapse
Affiliation(s)
- Elisabeth Pellegrini
- Endocrinologie Moléculaire de la Reproduction, UMR CNRS 6026, Université de Rennes 1, 35042 Rennes, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
67
|
Zhao C, Fujinaga R, Tanaka M, Yanai A, Nakahama KI, Shinoda K. Region-specific expression and sex-steroidal regulation on aromatase and its mRNA in the male rat brain: immunohistochemical and in situ hybridization analyses. J Comp Neurol 2007; 500:557-73. [PMID: 17120292 DOI: 10.1002/cne.21193] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The brain has an estrogen-biosynthetic potential resulting from the presence of neuronal aromatase, which controls the intraneural sex-steroidal milieu and is involved in brain sexual differentiation, psychobehavioral regulation, and neuroprotection. In the rat brain, three distinct aromatase-P450-immunoreactive (AromP450-I) neural groups have been categorized in terms of their peak expression time (fetal, fetoneonatal, and young-to-adult groups), suggesting the presence of region-specific regulation on brain AromP450. In the present study, we compared the expressions between AromP450 protein and mRNA by using immunohistochemistry and in situ hybridization with an ovary-derived cRNA probe in serial sections of fetal, fetoneonatal, and adult male rat brains and then performed steroidal manipulations to evaluate the sex-steroidal effects on AromP450 in adult orchiectomized and adrenalectomized (OCX + ADX) male rats. As a result, prominent mRNA signals were detected in the fetal (i.e., the anterior medial preoptic nucleus) and fetoneonatal (i.e., the medial preopticoamygdaloid neuronal arc) groups, although no detectable signal was found in the "young-to-adult" group (i.e., the central amygdaloid nucleus). In addition, the "fetoneonatal" AromP450-I neurons were prominently reduced in number and intensity after OCX + ADX and then were reinstated by the administration of dihydrotestosterone, testosterone, or 17beta-estradiol. In contrast, none of the sex steroids had any significant effects on the young-to-adult group. Several possible explanations were explored for why the young-to-adult group may differ in aromatase expression and regulation, including the possibility that distinct splicing variants or isozymes for aromatase exist in the rat brain.
Collapse
Affiliation(s)
- Changjiu Zhao
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University School of Medicine, Yamaguchi 755-8505, Japan
| | | | | | | | | | | |
Collapse
|
68
|
Karube M, Fernandino JI, Strobl-Mazzulla P, Strüssmann CA, Yoshizaki G, Somoza GM, Patiño R. Characterization and expression profile of the ovarian cytochrome P-450 aromatase (cyp19A1) gene during thermolabile sex determination in pejerrey,Odontesthes bonariensis. ACTA ACUST UNITED AC 2007; 307:625-36. [PMID: 17726668 DOI: 10.1002/jez.416] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cytochrome P450 aromatase (cyp19) is an enzyme that catalyzes the conversion of androgens to estrogens and may play a role in temperature-dependent sex determination (TSD) of reptiles, amphibians, and fishes. In this study, the ovarian P450 aromatase form (cyp19A1) of pejerrey Odontesthes bonariensis, a teleost with marked TSD, was cloned and its expression profile evaluated during gonadal differentiation at feminizing (17 degrees C, 100% females), mixed-sex producing (24 and 25 degrees C, 73.3 and 26.7% females, respectively), and masculinizing (29 degrees C, 0% females) temperatures. The deduced cyp19A1 amino acid sequence shared high identity (>77.8%) with that from other teleosts but had low identity (<61.8%) with brain forms (cyp19A2), including that of pejerrey itself. The tissue distribution analysis of cyp19A1 mRNA in adult fish revealed high expression in the ovary. Semi-quantitative reverse transcription polymerase chain reaction analysis of the bodies of larvae revealed that cyp19A1 expression increased before the appearance of the first histological signs of ovarian differentiation at the feminizing temperature but remained low at the masculinizing temperature. The expression levels at mixed-sex producing temperatures were bimodal rather than intermediate, showing low and high modal values similar to those at the feminizing and masculinizing temperatures, respectively. The population percentages of high and low expression levels at intermediate temperatures were proportional to the percentage of females and males, respectively, and high levels were first observed at about the time of sex differentiation of females. These results suggest that cyp19A1 is involved in the process of ovarian formation and possibly also in the TSD of pejerrey.
Collapse
Affiliation(s)
- Makiko Karube
- Faculty of Marine Science, Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Tokyo, Japan
| | | | | | | | | | | | | |
Collapse
|
69
|
Wong TT, Ijiri S, Zohar Y. Molecular Biology of Ovarian Aromatase in Sex Reversal: Complementary DNA and 5′-Flanking Region Isolation and Differential Expression of Ovarian Aromatase in the Gilthead Seabream (Sparus aurata)1. Biol Reprod 2006; 74:857-64. [PMID: 16421234 DOI: 10.1095/biolreprod.105.045351] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
To elucidate the involvement of aromatase in sex reversal, the gilthead seabream ovarian P450 aromatase (cyp19a1a) cDNA and its 5'-flanking region were isolated and characterized. Northern blot analysis revealed that only one cyp19a1a transcript (2.0 kb) is expressed in the ovary. Four cAMP-responsive elements were identified at the 5'-flanking region of seabream cyp19a1a indicating a high potential to respond to gonadotropin signaling. Studying the seasonal profile, two expression peaks of cyp19a1a transcripts in the ovarian tissues were found in July (about 15000 copies/ng total RNA) for ambisexual fish and in December (about 12000 copies/ng total RNA) for spawning females. Starting from September, transcript levels of cyp19a1a in the ovarian portions of the male-developing gonads gradually decreased. Furthermore, the ovarian portions of the female gonads expressed cyp19a1a at a significantly higher level than the ovarian portions of the male gonads after November. Taken together with levels of plasma estradiol in reversing females being significantly higher than those in developing males, the above results reinforce the importance of cyp19a1a in sex reversal. In vitro exposure of ovarian fragments to gonadotropins (hCG) at 1, 10, and 100 IU/ml significantly (P < 0.05) upregulated cyp19a1a expression. Additionally, expression of cyp19a1a displayed a stronger and significant correlation with the transcript expression of ovarian Lh receptor rather than Fsh receptor during the ambisexual stage. Our results indicate that the differential expression of cyp19a1a gene is associated with sex reversal and that gonadotropin signals (particularly Lh) may serve as major players in regulating the expression of cyp19a1a during the process of sex reversal.
Collapse
Affiliation(s)
- Ten-Tsao Wong
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA
| | | | | |
Collapse
|
70
|
Black MP, Balthazart J, Baillien M, Grober MS. Socially induced and rapid increases in aggression are inversely related to brain aromatase activity in a sex-changing fish, Lythrypnus dalli. Proc Biol Sci 2005; 272:2435-40. [PMID: 16243688 PMCID: PMC1559966 DOI: 10.1098/rspb.2005.3210] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Social interactions can generate rapid and dramatic changes in behaviour and neuroendocrine activity. We investigated the effects of a changing social environment on aggressive behaviour and brain aromatase activity (bAA) in a sex-changing fish, Lythrypnus dalli. Aromatase is responsible for the conversion of androgen into oestradiol. Male removal from a socially stable group resulted in rapid and dramatic (> or =200%) increases in aggression in the dominant female, which will become male usually 7-10 days later. These dominant females and recently sex-changed individuals had lower bAA but similar gonadal aromatase activity (gAA) compared to control females, while established males had lower bAA than all groups and lower gAA than all groups except dominant females. Within hours of male removal, dominant females' aggressive behaviour was inversely related to bAA but not gAA. These results are novel because they are the first to: (i) demonstrate socially induced decreases in bAA levels corresponding with increased aggression, (ii) identify this process as a possible neurochemical mechanism regulating the induction of behavioural, and subsequently gonadal, sex change and (iii) show differential regulation of bAA versus gAA resulting from social manipulations. Combined with other studies, this suggests that aromatase activity may modulate fast changes in vertebrate social behaviour.
Collapse
Affiliation(s)
- Michael P Black
- Georgia State University, Center for Behavioural Neuroscience, PO Box 3966, Atlanta, GA 30302-3966, USA.
| | | | | | | |
Collapse
|
71
|
van Nes S, Moe M, Andersen Ø. Molecular characterization and expression of twocyp19 (P450 aromatase) genes in embryos, larvae, and adults of Atlantic halibut (Hippoglossus hippoglossus). Mol Reprod Dev 2005; 72:437-49. [DOI: 10.1002/mrd.20373] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
72
|
Luckenbach JA, Early LW, Rowe AH, Borski RJ, Daniels HV, Godwin J. Aromatase cytochrome P450: cloning, intron variation, and ontogeny of gene expression in southern flounder (Paralichthys lethostigma). ACTA ACUST UNITED AC 2005; 303:643-56. [PMID: 16013049 DOI: 10.1002/jez.a.198] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Aromatase cytochrome P450 (P450arom) is the enzyme complex responsible for conversion of androgens to estrogens in vertebrates. Consequently, in some fishes its activity appears critical to ovarian differentiation. Southern flounder (Paralichthys lethostigma) is a commercially important flatfish in which females grow larger than males and sex determination is temperature sensitive. Through cloning of the P450arom gene in ovary and quantitative reverse transcription-polymerase chain reaction, we developed a biomarker for early female differentiation in southern flounder. The deduced amino acid sequence for southern flounder P450arom is similar to other teleosts. Comparison of P450arom intron sequences from fish of different populations revealed substantial inter-individual variation. Adult ovary and spleen exhibited high levels of P450arom mRNA, while P450arom mRNA was only weakly detected in testes. Brain, liver, intestine, kidney, gill, muscle, and heart showed little or no P450arom mRNA expression. Gonads of wild and hatchery-produced juvenile flounder of sizes spanning the period of sex differentiation initially exhibited low levels of P450arom mRNA followed by increases in some individuals and bifurcation into two clearly segregated groups (i.e., putative males and females) beginning at approximately 65 mm in total length. Gonadal histology confirmed predictions of sex based on P450arom expression in juvenile flounder, demonstrating that the patterns of P450arom expression observed relate to sex-specific differentiation. This research represents a unique approach to assessing sex differentiation in a natural population, and a powerful technique for better understanding mechanisms of flounder sex determination and rapidly defining conditions for controlling sex for aquaculture.
Collapse
Affiliation(s)
- John Adam Luckenbach
- Department of Zoology, North Carolina State University, Raleigh, North Carolina 27695-7617, USA
| | | | | | | | | | | |
Collapse
|
73
|
Strobl-Mazzulla PH, Moncaut NP, López GC, Miranda LA, Canario AVM, Somoza GM. Brain aromatase from pejerrey fish (Odontesthes bonariensis): cDNA cloning, tissue expression, and immunohistochemical localization. Gen Comp Endocrinol 2005; 143:21-32. [PMID: 15993101 DOI: 10.1016/j.ygcen.2005.02.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 02/01/2005] [Accepted: 02/21/2005] [Indexed: 11/24/2022]
Abstract
The brain-type aromatase (CYP19A2) cDNA from pejerrey Odontesthes bonariensis was characterized. Its sequence differs from the ovarian-derived aromatase (CYP19A1) previously reported for the same species. The cDNA is 2305bp in length and the deduced protein comprises 501 amino-acids. The percentage of identity was higher when compared to other brain-derived aromatase proteins (85-63%) and lower with ovarian-derived aromatases (64-57%). Pejerrey aromatases share 61% of identity. The tissue expression analysis showed that CYP19A2 was expressed in the kidney, brain, and pituitary gland of both sexes and also in the ovary, but not in the eye, spleen, liver, gill, and testis. Semi-quantitative RT-PCR analysis of different brain areas revealed that CYP19A2 was expressed significantly higher in anterior male brain areas than in the corresponding female areas, and also when compared to posterior brain areas from both sexes. An immunological analysis using a polyclonal anti-teleost aromatase showed immunoreactive aromatase cells bordering the telencephalic ventricle and a strong signal in the ependymal cells of the preoptic area and the hypothalamus. In the optic tectum immunoreactive aromatase cells were labeled in the ventral wall and in the ependymal layer of the third and fourth ventricle with lateral projections. In the pituitary gland immunoreactive aromatase cells could be found in the rostral and proximal pars distalis. In this gland, aromatase fibers were also detected in different areas; many of them concentrated around blood vessels.
Collapse
Affiliation(s)
- Pablo H Strobl-Mazzulla
- Laboratorio de Ictiofisiología y Acuicultura, Instituto de Investigaciones Biotecnológicas/Instituto Tecnológico de Chascomús (CONICET-UNSAM), C.C. 164, (B7130IWA) Chascomús, Provincia de Buenos Aires, Argentina
| | | | | | | | | | | |
Collapse
|
74
|
Sundaray JK, Ohta K, Yamaguchi A, Kitano T, Matsuyama M. Isolation, cloning, sequencing of brain type aromatase and its expression in male and female Wrasse, Pseudolabrus sieboldi. FISH PHYSIOLOGY AND BIOCHEMISTRY 2005; 31:137-141. [PMID: 20035447 DOI: 10.1007/s10695-006-0015-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Pseudolabrus sieboldi, wrasse being a diurnal spawner provides a good opportunity to study the endocrine mechanism of estrogen formation in brain and gonads. Moreover, an extremely large amount of E2 was produced in serum and testis of wrasse. It is assumed that the presence of E2 may play a major role in diurnal gametogenesis in male fish. In this study brain type aromatase have been isolated, cloned and sequenced from the brain of wrasse. Further, the expression pattern of brain type aromatase in gonads and adult tissue of male and female fish have been analyzed. In addition, the diurnal expression pattern of brain type aromatase in both male and female fish brain during spawning season have been analyzed.The P450arom (br) was isolated, cloned and sequenced from both male and female bamboleaf wrasse. The P450arom (br) gene (1877 sequenced nucleotide) contains an ORF of 1470 bp, a 5'-UTR of 18 bp and at least 407 bp in 3'-UTR. The amino acid sequence homology in the coding region of wrasse P450arom (br) is high compared to that of medaka, Oryzias latipes (80%), rainbow trout type 2, Oncorhynchu mykiss (78.2%), fugu, Takifugu ribripes (78%) rainbow trout type 1, (76%), goldfish, Carassius auratus (66.8%) and zebrafish, Danio rerio (66.2%). Expression study reveals that P450arom (br) mRNA were most abundant in brains of both male and female fish throughout the day during the spawning season. RT-PCR study revealed that P450arom (br) was expressed in skin, anal fin and tail fin of both male and female wrasse. P450arom (br) was not detected at any time of the spawning day in either ovary or testis of wrasse.
Collapse
Affiliation(s)
- J K Sundaray
- Kakdwip Research Center, Central Institute of Brackish Water Aquaculture, Kakdwip, West Bengal, 743 347, India,
| | | | | | | | | |
Collapse
|
75
|
Wilson JY, McArthur AG, Stegeman JJ. Characterization of a cetacean aromatase (CYP19) and the phylogeny and functional conservation of vertebrate aromatase. Gen Comp Endocrinol 2005; 140:74-83. [PMID: 15596073 DOI: 10.1016/j.ygcen.2004.10.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 09/29/2004] [Accepted: 10/12/2004] [Indexed: 11/17/2022]
Abstract
Aromatase (cytochrome P450 19, CYP19, P450arom) is the enzyme responsible for the production of estrogens, hormones critical for development and reproduction. Aromatase was sequenced from a white-sided dolphin (Lagenorhynchus acutus) ovary, transiently transfected into HEK 293 cells, and the expressed protein was characterized for aromatase activity in the presence of androstenedione and testosterone and after exposure to the aromatase inhibitor letrazole. The Kms for androstenedione and testosterone were 63.5 and 75 nM, respectively, values that are very similar to those reported for other mammalian aromatases. A Bayesian phylogenetic analysis of the vertebrate aromatases was performed on the amino acid sequences of aromatases from fish, amphibians, reptiles, birds, and mammals. Based on known species phylogeny, the cetacean aromatase showed an expected grouping with artiodactyls (cow, sheep, and goat). An analysis of functional divergence showed strong conservation of aromatase across the entire protein, which indicates that the observed sequence divergence is functionally neutral.
Collapse
Affiliation(s)
- Joanna Y Wilson
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
| | | | | |
Collapse
|
76
|
Menuet A, Pellegrini E, Brion F, Gueguen MM, Anglade I, Pakdel F, Kah O. Expression and estrogen-dependent regulation of the zebrafish brain aromatase gene. J Comp Neurol 2005; 485:304-20. [PMID: 15803511 DOI: 10.1002/cne.20497] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Compared with adult mammals, the brain of teleost fish is characterized by an extremely high capacity to aromatize androgens into estrogens, and this metabolic activity results from the expression of a specific brain aromatase (AroB) generated by the cyp19b gene. In this study, we first generated antibodies to zebrafish AroB and used them to map AroB-positive structures in the brain of adult zebrafish. We show that AroB is exclusively expressed in radial glial cells, mainly in the olfactory bulbs, telencephalon, preoptic area, and hypothalamus. Second, we investigated in vivo and in vitro the mechanisms involved in the estradiol (E2) regulation of the cyp19b gene. By means of whole-mount hybridization and immunohistochemistry on zebrafish embryos and larvae, we confirmed the E2-dependent upregulation of the cyp19b gene, and we show that E2 triggers AroB expression in radial glial cells mainly in the preoptic area and mediobasal hypothalamus of 48 hpf (hours post fertilization) and 108 hpf larvae. In addition, an in vitro analysis of 0.5 kb of the promoter region of the cyp19b gene demonstrated that this E2-dependent regulation involves a direct transcriptional action of estrogen receptors requiring estrogen-responsive elements. However, the data obtained on different cell lines demonstrate that a glial cell context is necessary for full E2 induction. The correlation between our in vivo and in vitro data suggests that the E2-dependent upregulation of AroB is favored by a glial cell context.
Collapse
Affiliation(s)
- Arnaud Menuet
- Endocrinologie Moléculaire de la Reproduction, Unité Mixte de Recherche 6026 Centre National de la Recherche Scientifique, Université de Rennes 1, 35042 Rennes, France
| | | | | | | | | | | | | |
Collapse
|
77
|
Bobes RJ, Miranda C, Pérez-Martinez M, Luu-The V, Romano MC. Isolation and characterization of goat ovarian aromatase cDNA: assessment of the activity using an intact cell system and placental expression. Theriogenology 2004; 62:532-43. [PMID: 15226009 DOI: 10.1016/j.theriogenology.2003.11.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Accepted: 11/06/2003] [Indexed: 11/28/2022]
Abstract
Goat ovarian follicles produce estrone and estradiol from androgens. The synthesis of C18 estrogens from C19 androgens requires cytochrome P450 aromatase, but little information about this key enzyme is available in the goat. We report here for the first time the cDNA sequence of the goat ovarian aromatase, the activity of the enzyme in a cell system, and its expression in the term goat placenta. A cDNA library from goat ovarian poly(A)+ RNA was constructed. Human aromatase cDNA was selected as probe to screen the library; several clones were isolated, but none was complete. The longest clone was 3.1 kb long, but it lacked the sequence coding for a few amino acids in the NH(2)-terminal. To obtain the missing sequence, we performed reverse amplification of the cDNA end (RACE). Sequence analysis indicated that goat aromatase possessed a very long 3'-untranslated region ( approximately 1790 bp), and a polyadenylation signal (AATAAA) located at position 3320 downstream from the ATG start codon. The coding region of goat cDNA was inserted in an expression vector and transfected into HEK-293 cells that were cultured in presence of [14C]-androstenedione, steroids extracted and further separated by TLC. The transfected cells efficiently transformed [14C]-androstenedione into estrone. This activity was inhibited by 4-hydroxyandrostenedione. We also investigated the presence of mRNA for P450 aromatase in the goat placenta, using reverse transcription-polymerase chain reaction (RT-PCR) and primers derived from the cDNA ovarian sequence and confirmed the expression of the mRNA in term placenta.
Collapse
Affiliation(s)
- Raúl José Bobes
- Dpto. de Fisiología, Biofisica y NC, CINVESTAV-IPN, Apdo. Postal 14-740, 07000 México D.F., Mexico
| | | | | | | | | |
Collapse
|
78
|
Menuet A, Anglade I, Le Guevel R, Pellegrini E, Pakdel F, Kah O. Distribution of aromatase mRNA and protein in the brain and pituitary of female rainbow trout: Comparison with estrogen receptor alpha. J Comp Neurol 2003; 462:180-93. [PMID: 12794742 DOI: 10.1002/cne.10726] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Recent data indicate that estrogens locally produced in the brain by aromatization of androgens could be important for neurogenesis and brain repair. In this respect, fish are interesting because of the extremely high aromatase activity of their brain. In this study, the rainbow trout brain aromatase was cloned and riboprobes were used to map the distribution of cells expressing the corresponding mRNAs. A very strong hybridization signal was detected in the pituitary and in cells bordering the ventricles in the telencephalon and ventral diencephalon, with the highest expression in the preoptic area and hypothalamus. A weaker signal was detected in the ependymal layer bordering the torus semicircularis and optic tectum. This localization was fully confirmed by immunohistochemistry using antibodies against a teleost aromatase. In addition, this antibody showed that aromatase expression in fact corresponds to radial glial cells because immunoreactive cells had long cytoplasmic processes extending toward the pial surface. Because brain aromatase was shown to be upregulated by estradiol in fish, the distribution of aromatase mRNAs was compared with that of rainbow trout estrogen receptor alpha (rtERalpha) on adjacent sections. Although the highest aromatase expression was found in regions expressing rtERalpha, no obvious coexpression was found, as rtERalpha was never observed in radial cells. However, reverse transcriptase-polymerase chain reaction experiments performed on brain cell cultures enriched in glial cells suggest that a weak expression of rtERalpha in glial cells cannot be excluded. The possible role of the high brain aromatase content in fish could be related to the continuous growth of their central nervous system during adulthood.
Collapse
Affiliation(s)
- Arnaud Menuet
- Endocrinologie Moléculaire de la Reproduction, UMR CNRS 6026, Campus de Beaulieu, 35042 Rennes cedex, France
| | | | | | | | | | | |
Collapse
|
79
|
Kagawa H, Gen K, Okuzawa K, Tanaka H. Effects of luteinizing hormone and follicle-stimulating hormone and insulin-like growth factor-I on aromatase activity and P450 aromatase gene expression in the ovarian follicles of red seabream, Pagrus major. Biol Reprod 2003; 68:1562-8. [PMID: 12606429 DOI: 10.1095/biolreprod.102.008219] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
To clarify the mechanism of estradiol-17beta production in the ovarian follicle of red seabream, in vitro effects of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and insulin-like growth factor (IGF-I) on aromatase activity (conversion of testosterone to estradiol-17beta) and cytochrome P450 aromatase (P450arom) mRNA expression in ovarian fragments of red seabream were investigated. Of the growth factors used in the present study, only IGF-I stimulated both aromatase activity and P450arom gene expression in the ovarian fragments of red seabream. LH from red seabream pituitary, but not FSH, stimulated both aromatase activity and P450arom gene expression. IGF-I slightly enhanced the LH-induced aromatase activity and P450arom gene expression. These data and our previous results indicate that LH, but not FSH, stimulates estradiol-17beta production in the ovarian follicle of red seabream through stimulation of aromatase activity and P450arom gene expression and IGF-I enhances the LH-stimulated P450arom gene expression.
Collapse
Affiliation(s)
- Hirohiko Kagawa
- National Research Institute of Aquaculture, Fisheries Research Agency, Nansei, Mie 516-0193, Japan.
| | | | | | | |
Collapse
|
80
|
Ijiri S, Kazeto Y, Lokman PM, Adachi S, Yamauchi K. Characterization of a cDNA encoding P-450 aromatase (CYP19) from Japanese eel ovary and its expression in ovarian follicles during induced ovarian development. Gen Comp Endocrinol 2003; 130:193-203. [PMID: 12568797 DOI: 10.1016/s0016-6480(02)00589-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A cDNA encoding P450 aromatase (CYP19) was isolated from a Japanese eel (Anguilla japonica) ovarian cDNA library. This cDNA contains a complete open reading frame encoding 511 amino acid residues. The deduced amino acid sequence is 59% and 65% identical to the catfish and rainbow trout forms, respectively, and 52-54% to mammalian and chicken forms. Non-steroidogenic COS-7 cells transfected with the eel CYP19 cDNA converted exogenous androstenedione to estrone, thus verifying its identity. Northern blot analysis indicated that there was a single 2.1 kb transcript in the ovary. A 2.1 kb transcript was also found in the brain but not in the spleen, head kidney, kidney, or liver. Throughout ovarian development induced by weekly injections of salmon pituitary homogenate (SPH, 20 microg/g body weight), the 2.1 kb transcript was barely or not detectable in the ovaries. However, signals greatly increased in intensity in oocytes in the migratory nucleus stage and then decreased slightly in the post-ovulatory ovary. These changes in transcript levels are consistent with the changes in aromatase activity of ovarian follicles, suggesting that aromatase activity in ovarian follicles is mainly regulated at the transcriptional level. In addition, fadrozole was found to significantly inhibit aromatase activity in a heterologous expression system using COS-7 cells, which indicates that fadrozole treatment could be useful to control E(2) production during artificial maturation of eels.
Collapse
Affiliation(s)
- Shigeho Ijiri
- Division of Marine Biosciences, Graduate School of Fisheries Science, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan.
| | | | | | | | | |
Collapse
|
81
|
González A, Piferrer F. Characterization of aromatase activity in the sea bass: effects of temperature and different catalytic properties of brain and ovarian homogenates and microsomes. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2002; 293:500-10. [PMID: 12486810 DOI: 10.1002/jez.90005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Two aromatase genes have been discovered in the brain and ovary of some teleosts. However, data on native aromatase enzyme kinetics and thus actual catalytic activity are scarce in fish, impeding comparison of aromatase activity (AA) from different organs within and between species. In the present study, the tritiated water assay was optimized and validated to measure AA in the sea bass using 1 beta-[3H]-androstenedione as a substrate in crude homogenates and microsomes. Optimized assay variables included pH, temperature, buffer strength, incubation time, amount of fresh tissue, substrate, and cofactor concentration. Specificity of the assay was verified by using known inhibitors, inappropriate substrates, and heat-inactivation. Subcellular fractionation revealed ten-fold more activity in the microsomal over the cytosolic fraction. The assay was also validated by comparing results from the direct product isolation method. The validated assay described allows measurement of AA to levels as low as < 10 fmol/mg protein/hr. Sex differentiation is temperature-dependent in the sea bass. It was found that in the physiological range of temperatures where the sea bass can live, 10-30 degrees C, AA is highly dependent on temperature in a linear fashion (brain: r2 = 0.92; P < 0.001; ovary: r2 = 0.94; P < 0.001). When AA levels from brain and ovarian homogenates obtained from the same fish during the spawning season were compared, the respective Michaelis-Menten constant (Km) values were 7.3 nM vs. 4.6 nM, with no significant differences detected between the two tissues. Thus, sea bass aromatase has a very high affinity for androstenedione, similar to what has been found in goldfish, but much higher than other piscine or mammalian aromatases (30-435 nM). In contrast, the brain maximum reaction rate (Vmax 7.8 pmol/mg protein/hr) was four-fold higher (P < 0.001) than the ovarian Vmax (2.1 pmol/mg protein/hr). Consistent results were found using purified microsomes. Although this is the first time that the kinetic parameters are reported for a native piscine aromatase in two different tissues within the same fish, it remains to be determined whether this is a reflection of two distinct isoforms in this particular species.
Collapse
Affiliation(s)
- Alicia González
- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), 08003 Barcelona, Spain
| | | |
Collapse
|
82
|
Sylvia VL, Gay I, Hardin R, Dean DD, Boyan BD, Schwartz Z. Rat costochondral chondrocytes produce 17beta-estradiol and regulate its production by 1alpha,25(OH)(2)D(3). Bone 2002; 30:57-63. [PMID: 11792565 DOI: 10.1016/s8756-3282(01)00630-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Prior studies have shown that 17beta-estradiol (17beta-E(2)) regulates growth plate chondrocyte maturation and differentiation. This study examines the hypothesis that 17beta-E(2) is a local regulator of rat costochondral growth plate chondrocytes by determining whether these cells express aromatase mRNA and enzyme activity, produce 17beta-E(2), and regulate 17beta-E(2) production by vitamin D(3) metabolites in a gender-specific and cell-maturation-dependent manner. Aromatase gene expression was assessed by reverse transcription-polymerase chain reaction (RT-PCR) and northern analysis of total RNA from male and female chondrocytes. Aromatase specific activity was measured in cell layer lysates of confluent male and female rat costochondral resting zone (RC) and growth zone (GC) cartilage cells that had been treated for 24 h with 1alpha, 25(OH)(2)D(3), 24R,25(OH)(2)D(3), or transforming growth factor (TGF)-beta1. 17beta-E(2) released into the culture media of treated cells was measured by radioimmunoassay (RIA). Female RC cells expressed the highest levels of aromatase mRNA compared with male RC cells and both male and female GC cells. Aromatase activity was present in male and female cells and was 1.6 times greater in female RC cells than female GC cells; male RC and GC cells displayed comparable levels. All cultures produced 17beta-E(2), with a 2.5-fold greater production by female RC cells than female GC cells or either cell type from male rats. Treatment of cultures with 1alpha,25(OH)(2)D(3) caused a dose-dependent increase in 17beta-E(2) production by female RC (1.5-fold greater than control cells) and female GC (threefold greater than control cells) cells. In contrast, 1alpha,25(OH)(2)D(3) had no effect on male GC cells and increased production in male RC cells by only 10% at the highest concentration of 1alpha,25(OH)(2)D(3) used. Neither 24R, 25(OH)(2)D(3) nor TGF-beta1 had an effect on 17beta -E(2) production. These results support our hypothesis and indicate that 17beta-E(2) is most likely a local regulator of rat costochondral growth plate chondrocytes.
Collapse
Affiliation(s)
- V L Sylvia
- Department of Orthopaedics, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
| | | | | | | | | | | |
Collapse
|
83
|
Kazeto Y, Ijiri S, Place AR, Zohar Y, Trant JM. The 5'-flanking regions of CYP19A1 and CYP19A2 in zebrafish. Biochem Biophys Res Commun 2001; 288:503-8. [PMID: 11676471 DOI: 10.1006/bbrc.2001.5796] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This report describes the structure of the 5'-flanking regions of both the CYP19A1 and A2 genes that were isolated from the genome of the zebrafish (Danio rerio). Consensus sequences of three cAMP-responsive elements (CRE), an aryl hydrocarbon-responsive element (AhR/Arnt), a steroidogenic factor 1 (SF-1) site, and a TATA box were observed in the 5'-flanking region of CYP19A1. In contrast, the 5'-flanking region of CYP19A2 was located upstream of an untranslated exon and possessed consensus sequences of a single CRE, an estrogen-responsive element (ERE), a peroxisome proliferator-activated receptor alpha/retinoid X receptor alpha heterodimer-responsive element (PPARalpha/RXRalpha), and a TATA box. Primer extension analysis revealed that the predominant transcription initiation sites for CYP19A1 and A2 transcripts were 28 and 91 bp upstream from the putative translation initiation codon, respectively. These analyses indicate that substantially different regulators, including a variety of environmental xenobiotics, control the expression the two CYP19 genes.
Collapse
Affiliation(s)
- Y Kazeto
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA
| | | | | | | | | |
Collapse
|
84
|
Okubo K, Nagata S, Ko R, Kataoka H, Yoshiura Y, Mitani H, Kondo M, Naruse K, Shima A, Aida K. Identification and characterization of two distinct GnRH receptor subtypes in a teleost, the medaka Oryzias latipes. Endocrinology 2001; 142:4729-39. [PMID: 11606438 DOI: 10.1210/endo.142.11.8475] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We report the identification and characterization of two distinct GnRH receptor (GnRH-R) subtypes, designated GnRH-R1 and GnRH-R2, in a model teleost, the medaka Oryzias latipes. These seven-transmembrane receptors of the medaka contain a cytoplasmic C-terminal tail, which has been found in all other nonmammalian GnRH-Rs cloned to date. The GnRH-R1 gene is composed of three exons separated by two introns, whereas the GnRH-R2 gene has an additional intron and therefore consists of four exons and three introns. The GnRH-R1 and GnRH-R2 genes, both of which exist as single-copy genes in the medaka genome, were mapped to linkage groups 3 and 16, respectively. Inositol phosphate assays using COS-7 cells transfected with GnRH-R1 and GnRH-R2 demonstrated that they had remarkably different ligand sensitivities, although both receptors showed highest preference for chicken-II-type GnRH. Phylogenetic analysis showed the presence of three paralogous lineages for vertebrate GnRH-Rs and indicated that neither GnRH-R1 nor GnRH-R2 is the medaka ortholog to mammalian GnRH-Rs that lack a cytoplasmic tail. This, together with an observation that medaka-type GnRH had low affinity for GnRH-R1 and GnRH-R2, suggests that a third GnRH-R may exist in the medaka.
Collapse
Affiliation(s)
- K Okubo
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
85
|
Gen K, Okuzawa K, Kumakura N, Yamaguchi S, Kagawa H. Correlation between messenger RNA expression of cytochrome P450 aromatase and its enzyme activity during oocyte development in the red seabream (Pagrus major). Biol Reprod 2001; 65:1186-94. [PMID: 11566742 DOI: 10.1095/biolreprod65.4.1186] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In teleosts, estradiol-17beta (E2) is an important hormone responsible for oocyte development. To elucidate the molecular mechanisms underlying E2 biosynthesis, we characterized the structure of red seabream (Pagrus major) cytochrome P450 aromatase (P450(arom)) that is directly involved in E2 biosynthesis and found changes in mRNA levels of P450(arom) during oocyte development induced by implantation of gonadotropin-releasing hormone analogue. A cDNA clone encoding P450(arom) is 1779 base pairs in length and encodes a protein of 519 amino acids in length, with a calculated molecular weight of 58.9 kDa. Northern blot analysis showed that P450(arom) mRNA levels increased gradually from Day 8, when oocytes reached the secondary yolk globule stage, and were maintained at high levels at the day of spawning (Day 15). The P450(arom) mRNA levels increased in association with an increase of the gonadosomatic index (gonad weight/body weight x 100%), serum E2, and P450(arom) enzyme activity (in vitro conversion of testosterone to E2 in the ovarian fragments). Furthermore, an increase in mRNA levels of the LHbeta, but not FSHbeta, correlated with increased P450(arom) mRNA levels during the course of ovarian development. In addition, the levels of P450(arom) mRNA increased in isolated ovarian follicles during the course of vitellogenic oocyte growth and became undetectable in follicles at the migratory nucleus and the mature stages. These findings, together with those of the previous studies, suggest that LH, not FSH, may regulate E2 biosynthesis via increased levels of P450(arom) mRNA during oocyte development of red seabream.
Collapse
Affiliation(s)
- K Gen
- Inland Station, National Research Institute of Aquaculture, Fisheries Research Agency, Tamaki, Mie 519-0423, Japan.
| | | | | | | | | |
Collapse
|
86
|
Trant JM, Gavasso S, Ackers J, Chung BC, Place AR. Developmental expression of cytochrome P450 aromatase genes (CYP19a and CYP19b) in zebrafish fry (Danio rerio). THE JOURNAL OF EXPERIMENTAL ZOOLOGY 2001; 290:475-83. [PMID: 11555854 DOI: 10.1002/jez.1090] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cytochrome P450 aromatase (CYP19) is the terminal enzyme in the steroidogenic pathway that converts androgens (e.g., testosterone) into estrogens (e.g., estradiol). Regulation of this gene dictates the ratio of androgens to estrogens; therefore, appropriate expression of this enzyme is critical for reproduction as well as being pivotal in sex differentiation for most vertebrates. It is assumed that most vertebrates have a single CYP19 gene that is regulated by multiple tissue-specific promoter regions. However, the zebrafish (Danio rerio) has two genes (CYP19a and CYP19b), each encoding a significantly different protein and possessing its own regulatory mechanism. The primary purpose of this study was to determine the pattern of expression of each of the CYP19 genes in the developing zebrafish. A fluorescent-based method of real-time, quantitative RT-PCR provided the sensitivity and specificity to determine transcript abundance in single embryos/juveniles harvested at days 0 through 41 days post-fertilization (dpf), which encompasses the developmental events of sex determination and gonadal differentiation. CYP19 transcripts could be detected as early as 3 or 4 dpf, (CYP19a and CYP19b, respectively) and peak abundance was detected on day five. In general, the CYP19 genes differed significantly in the ontogeny of their expression. In most cases, the gonadal form of CYP19 (CYP19a) was more abundant than the brain form (CYP19b); however, unlike CYP19a, the pattern of CYP19b expression could be clearly segregated into two populations, suggesting an association with sex differentiation. Pharmacological steroids (ethinylestradiol and 17 alpha-methyltestosterone) enhanced the expression of the CYP19b gene at all three days examined (4, 6, and 10 dpf). These data suggest that the timely and appropriate expression of CYP19 is important in development and that the expression of CYP19b (the "extra-gonadal" form) may be associated with sexual differentiation if not sexual determination. J. Exp. Zool. 290:475-483, 2001.
Collapse
Affiliation(s)
- J M Trant
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA.
| | | | | | | | | |
Collapse
|
87
|
Kwon JY, McAndrew BJ, Penman DJ. Cloning of brain aromatase gene and expression of brain and ovarian aromatase genes during sexual differentiation in genetic male and female Nile tilapia Oreochromis niloticus. Mol Reprod Dev 2001; 59:359-70. [PMID: 11468772 DOI: 10.1002/mrd.1042] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A brain aromatase gene was identified from the Nile tilapia Oreochromis niloticus. The cDNA sequence of this gene differed from that of the ovarian aromatase gene previously reported from this species. Tissue specific expression for both brain and ovarian aromatase genes was examined in the tissues of adult tilapia. Brain aromatase mRNA was expressed in the brain, kidney, eye, ovary, and testis, but not in the liver and spleen. Ovarian aromatase mRNA was expressed in the brain, spleen, ovary, and testis but not in the eye, kidney, and liver. Differential aromatase gene expression between the sexes was investigated in all-male (XY) and all-female (XX) groups of tilapia fry from fertilisation throughout the sexual differentiation period. Semi-quantitative RT-PCR analysis revealed that the initiation of expression of both aromatase genes lay between 3 and 4 dpf (days post fertilisation) in both sexes. The level of brain aromatase mRNA gradually increased throughout the period studied with little difference between the sexes. This contrasted with marked sexual dimorphism of ovarian aromatase mRNA expression. In females, the expression level was maintained or increased gradually throughout ontogeny, while the level in males was dramatically down-regulated between 15 and 27 dpf. Subsequently, the level of ovarian aromatase mRNA expression fluctuated slightly in both sexes, with the expression in females always being higher than in males. These findings clearly suggest that ovarian aromatase plays a decisive role in sexual differentiation in this species and that this is achieved by down-regulation of the expression of this gene in males. Mol. Reprod. Dev. 59: 359-370, 2001.
Collapse
Affiliation(s)
- J Y Kwon
- Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, United Kingdom
| | | | | |
Collapse
|
88
|
Bouraïma H, Hanoux V, Mittre H, Féral C, Benhaïm A, Leymarie P. Expression of the rabbit cytochrome P450 aromatase encoding gene uses alternative tissue-specific promoters. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:4506-12. [PMID: 11502211 DOI: 10.1046/j.1432-1327.2001.02375.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of the present study was to analyse the tissue-specific expression of various promoter-derived transcripts from the gene encoding rabbit aromatase cytochrome P450. A new promoter, named I.r, was identified, and promoters II and I.r were sequenced. Promoter I.r-derived transcripts were found in preovulatory granulosa cells, corpus luteum, placenta and adipose tissue. An alternative splice variant of this transcript was found with tissue-specific preference. Tissue-specific expression of promoter-derived variants was studied in the ovary before and after ovulation. While the level of promoter II-derived transcript decreased dramatically after ovulation, that of promoter I.r-derived transcript remained unchanged, indicating that promoter II and promoter I.r were not controlled by a single regulation system. The existence of this dual system of regulation suggests that the rabbit ovary could be a useful model to study the promoter-specific regulation of aromatase.
Collapse
Affiliation(s)
- H Bouraïma
- Laboratoire de Biochimie, UPRES EA 2608, USC INRA, CHU Côte de Nacre, Université de Caen, France.
| | | | | | | | | | | |
Collapse
|
89
|
Zhao J, Mak P, Tchoudakova A, Callard G, Chen S. Different catalytic properties and inhibitor responses of the goldfish brain and ovary aromatase isozymes. Gen Comp Endocrinol 2001; 123:180-91. [PMID: 11482939 DOI: 10.1006/gcen.2001.7661] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The brain and ovarian aromatase isozymes of goldfish (Carassius auratus) are encoded by different CYP19 genes. This study measured aromatase activity in the goldfish brain tissues. For a direct comparison of the properties of the two aromatase isozymes, Chinese hamster ovary cells were stably transfected with brain- and ovary-derived cDNAs (respectively, p450 arom B and -A) and the properties of the expressed isozymes were compared. The kinetic parameters of the two isozymes were determined using androstenedione and testosterone as substrates and compared to those of human aromatase. Inhibition profile analyses on the two isozymes were performed using seven inhibitors [4-hydroxyandrostenedione, 7 alpha-(4'-amino)phenylthio-1,4-androstadiene-3,17-dione, bridge (2,19-methyleneoxy)androstene-3,17-dione, aminoglutethimide (AG), CGS 20267, ICI D1033, and vorozole]. Except for AG, the compounds tested were found to be much stronger inhibitors against the ovary enzyme than the brain enzyme. In addition, the ovary isoform was more sensitive to two phytoestrogens, chrysin and 7,8-dihydroxyflavone, than the brain form. These studies reveal that catalytic properties of the goldfish aromatase isoforms are significantly different from those of human aromatase. In addition, differences in the K(i) values of aromatase inhibitors for the two goldfish isoforms suggest structural variance in the active sites of these isozymes.
Collapse
Affiliation(s)
- J Zhao
- Division of Immunology, Beckman Research Institute of the City of the Hope, Duarte, California 91010, USA
| | | | | | | | | |
Collapse
|
90
|
D'Cotta H, Fostier A, Guiguen Y, Govoroun M, Baroiller JF. Aromatase plays a key role during normal and temperature-induced sex differentiation of tilapia Oreochromis niloticus. Mol Reprod Dev 2001; 59:265-76. [PMID: 11424212 DOI: 10.1002/mrd.1031] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In the tilapia Oreochromis niloticus, sex is determined genetically (GSD), by temperature (TSD) or by temperature/genotype interactions. Functional masculinization can be achieved by applying high rearing temperatures during a critical period of sex differentiation. Estrogens play an important role in female differentiation of non-mammalian vertebrates. The involvement of aromatase, was assessed during the natural (genetic all-females and all-males at 27 degrees C) and temperature-induced sex differentiation of tilapia (genetic all-females at 35 degrees C). Gonads were dissected between 486--702 degree x days. Aromatase gene expression was analyzed by virtual northern and semi-quantitative RT-PCR revealing a strong expression during normal ovarian differentiation concomitant with high levels (465 +/- 137 fg/g) of oestradiol-17 beta (E2-17 beta). This was encountered in gonads after the onset of ovarian differentiation (proliferation of both stromal and germ cells prior to ovarian meiosis). Genetic males exhibited lower levels of aromatase gene expression and E2-17 beta quantities (71 +/- 23 fg/ g). Aromatase enzyme activity in fry heads established a sexual dimorphism in the brain, with high activity in females (377.9 pmol/head/hr) and low activity in males (221.53 pmol/head/hr). Temperature induced the masculinization of genetic females to a different degree in each progeny, but in all cases repression of aromatase expression was encountered. Genetic males at 35 degrees C also exhibited a repression of aromatase expression. Aromatase brain activity decreased by nearly three-fold in the temperature-masculinized females with also a reduction observed in genetic males at 35 degrees C. This suggests that aromatase repression is required in the gonad (and perhaps in the brain) in order to drive differentiation towards testis development. Mol. Reprod. Dev. 59:265-276, 2001.
Collapse
Affiliation(s)
- H D'Cotta
- CIRAD-EMVT (Centre de Coopération International en Recherche Agronomique pour le Développement), Station SCRIBE-INRA, Campus de Beaulieu, Rennes, France.
| | | | | | | | | |
Collapse
|
91
|
Kishida M, McLellan M, Miranda JA, Callard GV. Estrogen and xenoestrogens upregulate the brain aromatase isoform (P450aromB) and perturb markers of early development in zebrafish (Danio rerio). Comp Biochem Physiol B Biochem Mol Biol 2001; 129:261-8. [PMID: 11399458 DOI: 10.1016/s1096-4959(01)00319-0] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Estrogen synthesized in the brain itself by the action of cytochrome P450 aromatase (P450arom) is known to have permanent organizing effects on the developing CNS. In fish, estrogen upregulates the predominant brain isoform (P450aromB), implying that xenoestrogens (XE) could act as neurodevelopmental toxicants by altering P450aromB. To test this hypothesis, zebrafish embryos were exposed to 17beta-estradiol (E(2)), diethylstilbestrol (DES, a potent agonist), and bisphenol A (BPA, a weak agonist). RT-PCR/Southern transfer analysis showed that E(2) (0.01-10 microM) upregulated P450aromB in a dose-response manner. The effect of DES (0.01 microM) was similar to 1 microM E(2) (three- to four-fold higher than control), but BPA was less effective (<threefold increase at 10 microM). mRNA levels of the predominant ovarian isoform (P450aromA) were unchanged by estrogen. Treatment with E(2) (0.1-10 microM) between 2 and 72 hpf had dose-response effects on mortality and hatching and induced a 'curved tail down' phenotype characteristic of mutants with defects of early CNS development. The critical period of estrogen sensitivity for effects on mortality and curved tails was 2-24 hpf, whereas hatching effects were both stage- and duration-dependent. Developmental effects of DES and BPA were similar to E(2) but testosterone, and 5alpha-dihydrotestosterone were ineffective. 17alpha-Estradiol showed a small but significant effect on curved tails. We conclude that P450aromB mRNA is a sensitive marker of XE effect during embryogenesis, but further studies are required to determine whether changes in neural aromatase expression and estrogen biosynthesis have consequences for CNS development.
Collapse
Affiliation(s)
- M Kishida
- Department of Biology, Boston University, 5 Cummington Street, 02215, Boston, MA, USA.
| | | | | | | |
Collapse
|
92
|
Chiang EF, Yan YL, Guiguen Y, Postlethwait J. Two Cyp19 (P450 aromatase) genes on duplicated zebrafish chromosomes are expressed in ovary or brain. Mol Biol Evol 2001; 18:542-50. [PMID: 11264405 DOI: 10.1093/oxfordjournals.molbev.a003833] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cytochrome P450 aromatase (Cyp19) is an enzyme catalyzing the synthesis of estrogens, thereby controlling various physiological functions of estrogens. We isolated two cyp19 cDNAs, termed cyp19a and cyp19b, respectively, from zebrafish. These genes are located in linkage groups 18 and 25, respectively. Detailed gene mapping indicated that zebrafish linkage groups 18 and 25 may have arisen from the same ancestral chromosome by a chromosome duplication event. Cyp19a is expressed mainly in the follicular cells lining the vitellogenic oocytes in the ovary during vitellogenesis. Cyp19b is expressed abundantly in the brain, at the hypothalamus and ventral telencephalon, extending to the olfactory bulbs. The expression of duplicated cyp19 genes at two different tissues highlights the evolutionary significance of maintaining two active genes on duplicated zebrafish chromosomes for specific functions in the ovary and the brain.
Collapse
Affiliation(s)
- E F Chiang
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
| | | | | | | |
Collapse
|
93
|
Melo AC, Ramsdell JS. Sexual dimorphism of brain aromatase activity in medaka: induction of a female phenotype by estradiol. ENVIRONMENTAL HEALTH PERSPECTIVES 2001; 109:257-64. [PMID: 11333187 PMCID: PMC1240244 DOI: 10.1289/ehp.01109257] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In this study we identified sex-dependent dimorphism of brain aromatase in the teleost medaka and examined its regulation by sex steriods. We first investigated differential distribution of brain aromatase activity in sexually mature male and female medaka in serial coronal sections of the brain and identified the hypothalamic nuclei contained in each section using the brain atlas of medaka. In the brain of male medaka, high levels of activity are localized in sections containing the preoptic (POA) and suprachiasmatic nuclei (SC) (63-75 fmol/hr) and low levels in the nuclei periventricular dorsalis (HD), ventralis (HV), and caudalis (Hc), nuclei diffusus of lobulus inferiores (NDIL), and nuclei tuberi anteriores (TA) and posteriores (TP) (< 25 fmol/hr). In the brain of female medaka high aromatase activity is localized in sections containing the HD, HV, Hc, NDIL, TA, and TP (85-80 fmol/hr) and highly variable levels in the POA and SC (23-70 fmol/hr). The concentration and time dependency of the exposure of male medaka to estradiol on the total brain aromatase activity and morphologic sex characteristics were determined next. Estradiol increased the activity of brain aromatase in a concentration-dependent manner at 2.5 and 25 microg/L, but the increase was lower at higher concentrations of the hormone. The effect was time dependent, gradually increasing up to the fifth day of exposure, after which it reached a plateau. Estradiol induction of brain aromatase analyzed using Lineweaver-Burke plots of saturation assays revealed a non-first-order reaction. The results indicate that a positive feedback mechanism regulates brain aromatase and imply that the sexual dimorphic distribution of aromatase may be highly sensitive to physiologic cues and environmental perturbations in fish.
Collapse
Affiliation(s)
- A C Melo
- Marine Biotoxins Program, Center for Coastal Environmental Health and Biomolecular Research, National Atmospheric and Oceanic Administration-National Ocean Service, Charleston, SC 29412, USA
| | | |
Collapse
|
94
|
Kishida M, Callard GV. Distinct cytochrome P450 aromatase isoforms in zebrafish (Danio rerio) brain and ovary are differentially programmed and estrogen regulated during early development. Endocrinology 2001; 142:740-50. [PMID: 11159846 DOI: 10.1210/endo.142.2.7928] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
As a first step toward understanding estrogen's role in neurodevelopment, a PCR cloning strategy was used to isolate complementary DNAs encoding two distinct cytochrome P450 aromatase isoforms in adult zebrafish (Danio rerio) brain and ovary (termed P450aromB and P450aromA, respectively). Sequence and phylogenetic analysis showed that the zebrafish P450arom forms are orthologs of previously identified cyp19b and cyp19a genes in goldfish. On Northern blots, a single 4.4-kb transcript of the P450aromB subtype was identified in brain, and a 2.1-kb transcript of the P450aromA subtype in ovary, but RT-PCR showed a degree of overlapping expression. Both messenger RNA (mRNA) forms were detected in unfertilized eggs and 1.5 hpf (cleavage stage) embryos but declined by 12 hpf, indicating maternal transfer. A secondary rise in mRNAs between 12-24 hpf indicated the onset of embryonic cyp19b and -a transcription. Both mRNA species accumulated progressively to 120 hpf (early larval stage), but the relative magnitude and pattern of change was isoform specific. Estradiol (E(2,) 1 microM) advanced and amplified the developmentally programmed accumulation of P450aromB mRNA, and ICI164.384 decreased expressed levels, implying blockade of an endogenous estrogen mediated regulatory component. Conversely, E(2) had no effect or decreased P450aromA mRNA. The early embryonic expression of P450aromB and P450aromA isoforms, and differences in developmental programming and estrogen regulation, imply independent regulatory mechanisms and unique functions during major morphogenetic and differentiative events.
Collapse
Affiliation(s)
- M Kishida
- Department of Biology, Boston University, Boston, Massachusetts 02215, USA
| | | |
Collapse
|
95
|
Kazeto Y, Ijiri S, Matsubara H, Adachi S, Yamauchi K. Cloning of 17beta-hydroxysteroid dehydrogenase-I cDNAs from Japanese eel ovary. Biochem Biophys Res Commun 2000; 279:451-6. [PMID: 11118307 DOI: 10.1006/bbrc.2000.3974] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
17beta-hydroxysteroid dehydrogenase-I (17beta-HSD-I) is a key steroidogenic enzyme for estradiol-17beta (E(2)) production. cDNAs encoding 17beta-HSD-I were cloned for the first time in lower vertebrates from the ovary of a teleost, the Japanese eel. The deduced amino acid sequence from these cDNAs was approximately 50% identical to mammalian 17beta-HSD-Is. 17beta-HSD-I mRNA was not detected in previtellogenic ovaries by Northern blotting. However, transcript abundance increased in early vitellogenic ovaries obtained from fish artificially matured by gonadotropic treatment, but thereafter did not appear to change further. Recombinant 17beta-HSD-I expressed in human kidney 293 cells selectively converted estrone to E(2), but androstenedione, testosterone, or E(2) were not converted to any other steroids. Although it is widely accepted that E(2) is produced from testosterone in other species of teleosts, the substrate specificity of eel 17beta-HSD-I suggests that a steroidogenic pathway for production of E(2) from androstenedione via estrone exists in the Japanese eel ovary.
Collapse
Affiliation(s)
- Y Kazeto
- Division of Marine Biosciences, Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 minato-cho, Hakodate, Hokkaido, 041-8611, Japan.
| | | | | | | | | |
Collapse
|
96
|
Okubo T, Mok SC, Chen S. Regulation of aromatase expression in human ovarian surface epithelial cells. J Clin Endocrinol Metab 2000; 85:4889-99. [PMID: 11134158 DOI: 10.1210/jcem.85.12.7067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ovarian cancer originates mainly from surface epithelial cells, which are potential targets of estrogen action. Using immunohistochemistry and RT-PCR analysis, aromatase (estrogen synthetase) can be detected in human ovarian surface epithelial tumors. In this study, we functionally characterized the aromatase expressed in a primary cell culture, normal human ovarian surface epithelial (HOSE) 17. The apparent K(m) and V(max) values were determined to be 5.8 +/- 0.5 nM, and 0.3 +/- 0.0 pmol/mg.h, respectively. The aromatase activity in HOSE 17 cells can be induced effectively by phorbol esters and forskolin, suggesting that estrogen biosynthesis in HOSE 17 cells is mainly regulated through protein kinase C- and protein kinase A-mediated mechanisms. Exon I-specific RT-PCR revealed that phorbol esters predominantly up-regulated promoter II. Whereas forskolin treatment increased exon I.3A-containing messenger RNA, the aromatase activity remained low in the cells treated with this agent. In vitro transcription/translation analysis using plasmids containing T7 promoter and the human snail gene (SnaH) as a reporter capped with different untranslated exon Is revealed that exon PII-containing transcripts were translated more effectively than exon I. 3-containing transcripts. These findings explain why aromatase activity is higher in cells with the PII-containing transcripts than is cells with the I.3-containing transcripts. Our results indicate that aromatase is functionally expressed in human ovarian surface epithelial cells and its expression is regulated at both the transcriptional and translational levels.
Collapse
Affiliation(s)
- T Okubo
- Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA
| | | | | |
Collapse
|
97
|
Sampath Kumar R, Ijiri S, Trant JM. Changes in the expression of genes encoding steroidogenic enzymes in the channel catfish (Ictalurus punctatus) ovary throughout a reproductive cycle. Biol Reprod 2000; 63:1676-82. [PMID: 11090435 DOI: 10.1095/biolreprod63.6.1676] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In vertebrates, the growth and maturation of the ovarian follicle is dependent on the appropriate dynamics of sex steroid secretion, which is dictated by gene expression of the steroidogenic enzymes. The molecular aspects of steroid regulation are poorly understood in fishes, so as a first step we determined the pattern of expression of four key steroidogenic genes throughout the ovarian cycle in an annually spawning teleost, the channel catfish (Ictalurus punctatus). The abundance of transcripts encoding 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and cholesterol side chain cleavage (P450(scc)), 17 alpha-hydroxylase/lyase (P450(c17)), and aromatase (P450(arom)) were determined by rtqRT-PCR or ribonuclease protection assay and correlated to ovarian growth and plasma titers of estradiol (E(2)) and testosterone (T) in two populations of catfish. Elevations in transcript abundance for P450(c17), P450(scc), and P450(arom) were observed at the onset of ovarian recrudescence and during early vitellogenic growth of the oocytes; however, all three decreased precipitously with the completion of vitellogenesis. Changes in the expression of these genes strongly suggest a direct correlation to E(2) and T titers. Alternatively 3 beta-HSD transcript abundance was relatively stable throughout the year. This study suggests that the genes encoding the three steroidogenic cytochrome P450s have a similar regulatory mechanism.
Collapse
Affiliation(s)
- R Sampath Kumar
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21202, USA
| | | | | |
Collapse
|
98
|
Kazeto Y, Ijiri S, Todo T, Adachi S, Yamauchi K. Molecular cloning and characterization of Japanese eel ovarian P450c17 (CYP17) cDNA. Gen Comp Endocrinol 2000; 118:123-33. [PMID: 10753574 DOI: 10.1006/gcen.1999.7449] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As a first step in investigating the mechanism underlying the steroidogenic shift from the production of ovarian androgens (vitellogenic stage) to that of 17alpha-hydroxylated progestins (maturational stage) in Japanese eel during induced oogenesis, a cDNA encoding Japanese eel (Anguilla japonica) ovarian P450c17 (CYP17: steroid 17alpha-hydroxylase/C(17-20) lyase) was cloned and sequenced. This cDNA contained the complete coding region representing 510 amino acid residues, which showed high sequence homology to those of rainbow trout (74%) and mammals (45-55%). The protein encoded by this cDNA possessed high enzymatic activities of 17alpha-hydroxylase and C(17-20) lyase, thus quickly converting pregnenolone and progesterone to their respective delta(4) and delta(5) C19 products. P450c17 produced a single transcript of 2.4 kb in length, as assessed by Northern blot. Transcript levels of this enzyme significantly increased throughout artificially induced ovarian development. Considering this together with the previous data showing that C(17-20) lyase activity decreased from the vitellogenic to the maturational stage, whereas 17alpha-hydroxylase activity increased, the present data suggest that changes in C(17-20) lyase activity (the production of androgens) do not depend on transcriptional changes of the P450c17 gene.
Collapse
Affiliation(s)
- Y Kazeto
- Department of Biology, Faculty of Fisheries, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido, 041-8611, Japan.
| | | | | | | | | |
Collapse
|
99
|
Kwon JY, Haghpanah V, Kogson-Hurtado LM, McAndrew BJ, Penman DJ. Masculinization of genetic female Nile tilapia (Oreochromis niloticus) by dietary administration of an aromatase inhibitor during sexual differentiation. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/1097-010x(20000615)287:1<46::aid-jez6>3.0.co;2-x] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
100
|
Corbin CJ, Trant JM, Walters KW, Conley AJ. Changes in testosterone metabolism associated with the evolution of placental and gonadal isozymes of porcine aromatase cytochrome P450. Endocrinology 1999; 140:5202-10. [PMID: 10537150 DOI: 10.1210/endo.140.11.7140] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Differences in the catalytic activity of the placental and gonadal isozymes of porcine aromatase cytochrome P450 (P450arom) were examined in cell lines exhibiting stable expression of recombinant enzyme. Cell lines were selected that expressed high, but similar, immunodetectable levels of each isozyme based on Western analysis. Aromatase activity varied with growth in culture, decreasing at confluence from a peak reached between 50-80% cell density. Cells expressing the placental isozyme had 3-5 times higher catalytic activity (per mg protein) than those expressing the gonadal isozyme. The P450arom inhibitor fadrazole (1 microM) inhibited more than 97% of this activity, whereas another imidazole, etomidate (1 microM), selectively inhibited gonadal P450arom activity by 92%. Estrogen synthesis from androstenedione and testosterone was determined by RIA and confirmed by HPLC analysis, which also identified the accumulation of the 19-hydroxy and 19-oxo intermediates of the respective substrates. There was no evidence of other steroid metabolites accumulating in the media of cell lines expressing either isozyme. Tritiated water formed during aromatization of substrates 3H labeled at the C1 and C2 positions was stereo-selective for the beta orientation, but less so for testosterone than androstenedione during metabolism by the porcine placental (and human) isozyme than the gonadal isozyme. Testosterone showed a higher affinity for the porcine placental P450arom than the gonadal P450arom, but both isozymes had similar affinities for androstenedione. Testosterone was also aromatized more slowly than androstenedione by the porcine gonadal P450arom. These data suggest that catalytic differences have arisen in the substrate binding pocket during the evolution of isozymes of porcine P450arom that affect androgen metabolism, particularly the aromatization of testosterone. The physiological significance of these differences to the reproductive biology of the pig remains to be determined.
Collapse
Affiliation(s)
- C J Corbin
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis 95616, USA
| | | | | | | |
Collapse
|