Aromatase expression and role of estrogens in male gonad : a review

The ability of the testis to convert irreversibly androgens into estrogens is related to the presence of a microsomal enzymatic complex named aromatase, which is composed of a specific glycoprotein, the cytochrome P450 aromatase (P450arom) and an ubiquitous reductase. The aromatase gene is unique in humans and contained 18 exons, 9 of them being translated. In the rat testis we have immunolocalized the P450arom not only in Leydig cells but also in germ cells and especially in elongated spermatids. Related to the stage of germ cell maturation, we have shown that the level of P450arom mRNA transcripts decreases, it is much more abundant in pachytene spermatocytes and round spermatids than in mature germ cells whereas the aromatase activity is 2–4 fold greater in spermatozoa when compared to the younger germ cells. Using a highly specific quantitative competitive RT-PCR method we have evidenced that several factors direct the expression of the aromatase gene in Leydig cells, Sertoli cells, pachytene spermatocytes and round spermatids, and it is obvious that promoter PII is the main one but other promoters could be concerned. In the bank-vole testis we have observed a positive correlation between a fully developed spermatogenesis and a strong immunoreactivity for both P450arom and estrogen receptor β not only in Sertoli cells but also in pachytene spermatocytes and round spermatids. Our recent data obtained from ejaculated human spermatozoa demonstrate the presence of aromatase both in terms of mRNA and protein, and in addition, we suggest that aromatase could be involved in the acquisition of sperm motility. Indeed in men the congenital aromatase deficiency is associated with severe bone maturation problems and sterility. Together with the widespread distribution of estrogen receptors in testicular cells these data clearly show that estrogens play a physiological role in the regulation of spermatogenesis in mammals

Estrogens: a new player in spermatogenesis.

The mammalian testis serves two main functions: production of spermatozoa and synthesis of steroids; among them, estrogens are the end products obtained from the irreversible transformation of androgens by aromatase. The aromatase is encoded by a single gene (cyp19) in humans which contains 18 exons, 9 of them being translated. In rat the aromatase activity is mainly located in Sertoli cells of immature animals and then in Leydig cells of adults. Moreover rat germ cells represent an additional source of estrogens: the amount of P450arom transcript is 3-fold higher in pachytene spermatocytes (PS) compared to gonocytes or round spermatids (RS); conversely, aromatase activity is more intense in haploid cells. Male germ cells of mice, bank vole, bear and monkey express also aromatase. In man besides Leydig cells, we have shown the presence of a biologically active aromatase and of estrogen receptors in ejaculated spermatozoa and in immature germ cells. Concerning aromatase, a 30% decrease of the amount of mRNA is observed in immotile compared to motile sperm fraction from the same sample; moreover the aromatase activity is also diminished of 34%. In asthenoteratozoospermic and teratozoospermic patients the aromatase gene expression is decreased by 67 and 52%, respectively when compared to normospermic controls. Statistical analyses between the sperm morphology and the aromatase/GAPDH ratio have revealed a high degree of correlation (r=-0.64) between the ratio and the percentage of abnormal spermatozoa (especially microcephaly and acrosmome malformations). Alterations of sperm number and motility have been described in men genetically deficient in aromatase, which together with our data, suggest a likely role for aromatase/estrogens in the acquisition of sperm motility. Therefore besides gonadotrophins and testosterone, estrogens produced locally should be considered as a physiologically relevant hormone involved in the regulation of spermatogenesis and spermiogenesis

IGF-1 stimulates synthesis of undersulfated proteoglycans and of hyaluronic acid by peritubular cells from immature rat testis

AbstractThe exposure of confluent peritubular (PT) cells from immature rat testis to insulin-like growth factor-1 (IGF-1) induced a time and dose-dependent increase of [35S]-sulfate and [3H]-d-glucosamine incorporations in newly synthesized proteoglycans (PG). This increased content of PG was the result of an enhancement of PG synthesis rather than a decreased rate of degradation. IGF-1 had no effect on the molecular weight of synthesized PG nor on the nature and distribution of the constitutive glycosaminoglycan chains, both in medium and in cell layer. The stimulation of PG synthesis by IGF-1 appeared to be due, at least partially, to an increase of glycosylation processes. IGF-1 effect was mediated by the classical tyrosine kinase signalling process, since IGF-1 action on PG synthesis was abolished by genistein and tyrphostin A9, two well known tyrosine kinase inhibitors. The increase of PG synthesis was accompanied with an undersulfation of constitutive glycosaminoglycan (GAG) chains (chondroitin sulfate and heparan sulfate chains) since the [35S]/[3H] ratio was reduced by about 20–25% in presence of IGF-1. Although the mechanism of hyaluronic acid synthesis was completely different from those of other GAG, IGF-1 also dramatically enhanced its production by PT cells

Effects of the Methanol Extract of Basella alba L (Basellaceae) on Steroid Production in Leydig Cells

In this study, Leydig cells were purified from 70 day-old Sprague Dawley male rats and incubated with 10 and 100 μg/mL of methanol extract of Basella alba (MEBa) for 4 hours followed by the evaluation of cell viability, steroid (testosterone and estradiol) production, and the level of aromatase mRNA. Results showed that MEBa did not affect Leydig cell viability. At the concentration of 10 μg/mL, MEBa significantly stimulated testosterone and estradiol production (p < 0.01 and p < 0.03, respectively), and enhanced aromatase mRNA level (p < 0.04). These observations suggest that MEBa directly stimulated testosterone, estradiol and aromatase mRNA levels in isolated Leydig cells

Tumor Banks : The cornerstone of basic research in urology : Editorial comment

That paper of Reis and co-workers is of great importance in the field of research since that will allow studies on a very well organized source of human materials kept in very good conditions. It is very important to save a lot of tissues (together with blood) and for many years. Thus, in order to avoid any problems and to meet scientists requirements for research project it is necessary to save duplicates / triplicates of tissues in at least two different places (not necessary in the same city). It is well known that saving tissues in only one -80°C freeze is dangerous and it is better to have different banks in order to avoid any problems of safety (in case of electric power defect) and security. I would suggest also to have a website in order to inform people in your country about the relevance of that bank and thus organize meeting for future scientific projects in that area. What is also important to consider is the cost of keeping these samples for many years with highly specialized apparatus as well as technicians who must be aware of these conditions

Leydig cell aromatase: from gene to physiology

Chapitre 13 International audienc

Aromatase and estrogens in man reproduction: a review and latest advances

ABSTRACT The mammalian testis is a complex organ which produces spermatozoa and synthesizes steroids. The transformation of androgens into estrogens is catalyzed by aromatase, an enzymatic complex encoded by a single copy-gene (cyp19) which contains 18 exons, 9 of them being translated. In man besides Leydig cells, we have demonstrated the existence of a biologically active aromatase in immature germ cells and in ejaculated spermatozoa. In addition the presence of estrogen receptors (ERa and ERß) in immature germ cells and in spermatozoa has been reported. Concerning aromatase, a 30% decrease of the amount of mRNA is observed in immotile compared to motile sperm fraction from the same sample. In asthenoteratozoospermic, teratozoospermic and asthenozoospermic patients, the aromatase gene expression is decreased respectively by 67%, 52% and 44%, when compared to normospermic controls. Statistical analyses between the sperm morphology and the aromatase/GAPDH ratio have revealed a high degree of correlation (r=-0.64) between that ratio and the percentage of abnormal spermatozoa (especially microcephaly). In men genetically deficient in aromatase diminutions of sperm number and motility have been published. Therefore besides gonadotrophins and testosterone, estrogens are likely playing a relevant role in spermiogenesis and human male gamete maturation

Estrogens-male hormones ?

International audienceThe cytochrome P450 aromatase is the terminal enzyme responsible for the irreversible transformation of androgens into estrogens; it is present in the endoplasmic reticulum membrane of cells and rather ubiquitous in its localization. The aromatase gene is unique in humans and its expression is regulated in a cell-specific manner via the alternative use of various promoters located in the first exon I of the CYP19 gene. The aromatase gene expression and its translation into a fully active protein have been shown in most of the testicular cells including germ cells as well as in the epithelial cells of the epididymis in mammals. Together with the widespread distribution of estrogen receptors (ERalpha and ERbeta) in the genital tract of the male, a physiological role for estrogens in the regulation of mammalian reproductive functions including the regulation of gonadotropin feedback, is now well recognized. Moreover, in men the aromatase deficiency is associated with severe bone maturation problems, alterations of lipid and sugar metabolism and sterility; but conversely an excess of estrogens is responsible for the impairment of spermatogenesis. In addition, estrogens play an important role in the control of osteoporosis and of atherosclerosis, especially in elderly men. Consequently, estradiol seems to be a critical factor not only for normal reproduction (at least for maturation and survival of germ cells) but also for various physiological processes and thus, estrogens should be now considered as "male hormones"

Estrogènes et spermatogenèse chez le rat (Thèse soutenue sur un ensemble de travaux)

La spermatogenèse, le processus permettant la formation des gamètes mâles, est sous le contrôle de nombreux facteurs et les estrogènes semblent être impliqués dans la régulation de ce mécanisme ainsi que dans sa mise en place. Les données de localisation de l aromatase et des ESRs dans le testicule de rat étant discordantes, nous avons réalisé une cartographie précise de leurs messagers et protéines dans le testicule de rat et nous avons montré que leur expression y est régulée finement. Ensuite, nous nous sommes intéressés au(x) rôle(s) potentiel(s) des estrogènes dans la spermatogenèse. Nous avons donc développé un modèle de culture de tubes séminifères de rats permettant de conserver les interactions physiques au sein de l épithélium séminifère. Le 17b-estradiol (E2) (10-9M) induit une augmentation de l expression des gènes des cyclines A1 et B1, spécifiquement dans les stades IX-I et cet effet impliquerait les ESRs et GPER, exprimés dans le testicule de rat adulte. A 30 jours, (mise en place de la première spermiogenèse), l E2 (10-9 M) induit une diminution de l expression des gènes des cyclines A1 et B1 qui ferait intervenir GPER. Par immunolocalisation, nous avons montré que le testicule de 30 jours exprime faiblement ESR1 mais très fortement GPER et ESR2. L analyse des séquences promotrices des gènes des cyclines, a mis en évidence l absence d éléments de réponse aux estrogènes et la présence de sites potentiels de régulation faisant intervenir d autres facteurs de transcription. Ainsi l E2 a un rôle et mettrait en jeu des acteurs différents en fonction de l âge dans le contrôle de la balance différenciation/apoptose dans la spermatogenèse de rat.Spermatogenesis, the process allowing male gametes formation, is under the control of numerous factors and estrogens seem to be implicated in the regulation of this mechanism and in its establishment. Data concerning aromatase and ESRs localization within the rat testis are in conflict, so we have realized the precise cartography of their transcripts and proteins in the rat testis and we have shown that their expression is very finely regulated. Then, we studied the potential role of estrogens in spermatogenesis. We have developed a culture model of rat seminiferous tubules allowing the preservation of physical interactions within the seminiferous epithelium. 17b-estradiol (E2) (10-9M) induces an increase of cyclins B1genes expression specifically in stages IX-I and this effect may involve ESRs and GPER, expressed in the adult rat testis. At 30 days (establishment of the first spermiogenesis), E2 (10-9M) triggers a decrease of cyclins A1 and B1 genes expression which may implicate GPER. Using immunolcalization, we have shown that 30 day-old rat testes express weak amounts of ESR1 and strong levels of GPER and ESR2. The analysis of cyclins A1 and B1 promoting sequences revealed the absence of estrogen response element and the presence of potential regulation sites involving other transcription factors. Thus, E2 plays a differential role and could involves different actors according to the age in the control of proliferation/apoptosis/balance in rat spermatogenesis.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

REGULATION DE L'EXPRESSION DE L'AROMATASE DANS LES CELLULES DE LEYDIG DE RAT MATURE

LE CYTOCHROME P450 AROMATASE EST L'ENZYME RESPONSABLE DE LA CONVERSION IRREVERSIBLE DES ANDROGENES EN ESTROGENES ; SA PRESENCE DANS LES CELLULES TESTICULAIRES DES MAMMIFERES EST BIEN ETABLIE. L'ETUDE DE DIFFERENTS MODULATEURS (ANDROGENES, GONADOTROPHINES ET CERTAINS FACTEURS PARACRINES) SUR L'ACTIVITE AROMATASE TESTICULAIRE A SUSCITE DE NOMBREUX TRAVAUX. CEPENDANT, LA REGULATION DE L'EXPRESSION DU GENE DE L'AROMATASE, EN PARTICULIER DANS LES CELLULES DE LEYDIG N'A PAS ETE RAPPORTEE. EN UTILISANT UNE TECHNIQUE DE RT-PCR QUANTITATIVE COMPETITIVE, NOUS AVONS MESURE APRES 24 HEURES DE CULTURE LES VARIATIONS DU TAUX DE MESSAGER SPECIFIQUE DE L'AROMATASE DANS LES CELLULES DE LEYDIG PURIFIEES DE RAT APRES ADDITION D'ANDROGENE (TESTOSTERONE, 5-DHT), DE GONADOTROPHINE (OLH) ET DE MILIEUX CONDITIONNES DE TUBES SEMINIFERES (STM) ; EN PARALLELE, DES DOSAGES DE L'ESTRADIOL ONT ETE REALISES. LA QUANTITE DE MESSAGER DE L'AROMATASE A PU ETRE DETECTEE EN ABSENCE ET EN PRESENCE DE TRAITEMENT, METTANT AINSI EN AVANT L'EXISTENCE D'UNE AROMATASE CONSTITUTIVE ET REGULEE DANS LES CELLULES DE LEYDIG. LE TAUX DE MESSAGER EST AUGMENTE EN PRESENCE DE TESTOSTERONE, SUBSTRAT DE L'AROMATASE MAIS EGALEMENT EN PRESENCE DE 5-DHT, ANDROGENE NON AROMATISABLE. L'AUGMENTATION DE LA PRODUCTION D'ESTRADIOL EST DONC LE REFLET D'UN EFFET DES ANDROGENES AU NIVEAU TRANSCRIPTIONNEL ET NON D'UNE AUGMENTATION DE LA DISPONIBILITE EN SUBSTRAT. LA OLH AGIT EGALEMENT AU NIVEAU TRANSCRIPTIONNEL VIA L'AMPC. ASSOCIEE A LA TESTOSTERONE, OLH PERMET D'AUGMENTER LA DEMI-VIE DES ARNM DE L'AROMATASE. LE STM REGULE POSITIVEMENT LES TAUX DE MESSAGERS DU CYTOCHROME P450 AROMATASE LEYDIGIEN EN PARALLELE AVEC DES MODIFICATIONS DU CYTOSQUELETTE. L'EFFET BIOLOGIQUE DU STM SUR L'AROMATASE S'EXERCE A PLUSIEURS NIVEAUX : LE PREMIER DIRECTEMENT SUR LA REGULATION DE L'EXPRESSION DU GENE VIA UNE SYNTHESE PROTEIQUE DE NOVO ET LE SECOND VIA UNE HAUSSE DE LA QUANTITE D'ESTRADIOL SANS NECESSITE D'UNE SYNTHESE PROTEIQUE DE NOVO. L'ORIGINE SERTOLIENNE DU OU DES FACTEUR(S) REGULANT L'EXPRESSION DU GENE DE L'AROMATASE A ETE CONFIRMEE PAR L'UTILISATION DE RATS TRAITES AU BUSULFAN. AU TERME DE CE TRAVAIL, IL APPARAIT DONC QUE LA REGULATION DE L'EXPRESSION DU GENE DE L'AROMATASE DANS LES CELLULES DE LEYDIG FAIT APPEL AU MOINS AU PROMOTEUR PII. ASSOCIES A UNE PRODUCTION D'ESTROGENES PLURICELLULAIRES DANS LE TESTICULE, NOS RESULTATS OUVRENT DES PERSPECTIVES EN PARTICULIER SUR L'ETUDE DE LA REGULATION DE L'EXPRESSION DU GENE DE L'AROMATASE DANS LES CELLULES SOMATIQUES ET GERMINALES PENDANT LE DEVELOPPEMENT TESTICULAIRE AVEC COMME OBJECTIF MIEUX CERNER LE ROLE DES ESTROGENES DANS LA PHYSIOLOGIE DE LA GONADE MALE.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF