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1.
Toxicol Appl Pharmacol ; 325: 61-70, 2017 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-28396216

RESUMO

Estrogen receptors (ERs) α and ß are distributed in most tissues of women and men. ERs are bound by estradiol (E2), a natural hormone, and mediate the pleiotropic and tissue-specific effects of E2, such as proliferation of breast epithelial cells or protection and differentiation of neuronal cells. Numerous environmental molecules, called endocrine disrupting compounds, also interact with ERs. Phytoestrogens belong to this large family and are considered potent therapeutic molecules that act through their selective estrogen receptor modulator (SERM) activity. Using breast cancer cell lines as a model of estrogen-dependent proliferation and a stably ER-expressing PC12 cell line as a model of neuronal differentiating cells, we studied the SERM activity of major dietary compounds, such as apigenin, liquiritigenin, daidzein, genistein, coumestrol, resveratrol and zearalenone. The ability of these compounds to induce ER-transactivation and breast cancer cell proliferation and enhance Nerve Growth Factor (NGF) -induced neuritogenesis was assessed. Surprisingly, although all compounds were able to activate the ER through an estrogen responsive element reporter gene, they showed differential activity toward proliferation or differentiation. Apigenin and resveratrol showed a partial or no proliferative effect on breast cancer cells but fully contributed to the neuritogenesis effect of NGF. However, daidzein and zearalenone showed full effects on cellular proliferation but did not induce cellular differentiation. In summary, our results suggest that the therapeutic potential of phytoestrogens can diverge depending on the molecule and the phenotype considered. Hence, apigenin and resveratrol might be used in the development of therapeutics for breast cancer and brain diseases.


Assuntos
Neoplasias das Glândulas Suprarrenais/tratamento farmacológico , Antineoplásicos Fitogênicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Proliferação de Células/efeitos dos fármacos , Dieta , Neurogênese/efeitos dos fármacos , Feocromocitoma/tratamento farmacológico , Fitoestrógenos/farmacologia , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Neoplasias das Glândulas Suprarrenais/genética , Neoplasias das Glândulas Suprarrenais/metabolismo , Neoplasias das Glândulas Suprarrenais/patologia , Animais , Apigenina/farmacologia , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Quimiocina CXCL12/genética , Quimiocina CXCL12/metabolismo , Relação Dose-Resposta a Droga , Receptor alfa de Estrogênio/efeitos dos fármacos , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Isoflavonas/farmacologia , Células MCF-7 , Proteínas do Tecido Nervoso/metabolismo , Neuritos/efeitos dos fármacos , Neuritos/metabolismo , Neuritos/patologia , Células PC12 , Feocromocitoma/genética , Feocromocitoma/metabolismo , Feocromocitoma/patologia , Ratos , Elementos de Resposta , Resveratrol , Estilbenos/farmacologia , Transcrição Gênica/efeitos dos fármacos , Transfecção , Zearalenona/farmacologia
2.
Cell Commun Signal ; 15(1): 26, 2017 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-28666461

RESUMO

BACKGROUND: Estrogen receptors (ER) α and ß are found in both women and men in many tissues, where they have different functions, including having roles in cell proliferation and differentiation of the reproductive tract. In addition to estradiol (E2), a natural hormone, numerous compounds are able to bind ERs and modulate their activities. Among these compounds, phytoestrogens such as isoflavones, which are found in plants, are promising therapeutics for several pathologies. Glyceollins are second metabolites of isoflavones that are mainly produced in soybean in response to an elicitor. They have potentially therapeutic actions in breast cancer by reducing the proliferation of cancer cells. However, the molecular mechanisms driving these effects remain elusive. METHODS: First, to determine the proliferative or anti-proliferative effects of glyceollins, in vivo and in vitro approaches were used. The length of epithelial duct in mammary gland as well as uterotrophy after treatment by E2 and glyceollins and their effect on proliferation of different breast cell line were assessed. Secondly, the ability of glyceollin to activate ER was assessed by luciferase assay. Finally, to unravel molecular mechanisms involved by glyceollins, transcriptomic analysis was performed on MCF-7 breast cancer cells. RESULTS: In this study, we show that synthetic versions of glyceollin I and II exert anti-proliferative effects in vivo in mouse mammary glands and in vitro in different ER-positive and ER-negative breast cell lines. Using transcriptomic analysis, we produce for the first time an integrated view of gene regulation in response to glyceollins and reveal that these phytochemicals act through at least two major pathways. One pathway involving FOXM1 and ERα is directly linked to proliferation. The other involves the HIF family and reveals that stress is a potential factor in the anti-proliferative effects of glyceollins due to its role in increasing the expression of REDD1, an mTORC1 inhibitor. CONCLUSION: Overall, our study clearly shows that glyceollins exert anti-proliferative effects by reducing the expression of genes encoding cell cycle and mitosis-associated factors and biomarkers overexpressed in cancers and by increasing the expression of growth arrest-related genes. These results reinforce the therapeutic potential of glyceollins for breast cancer.


Assuntos
Proliferação de Células/efeitos dos fármacos , Glândulas Mamárias Animais/efeitos dos fármacos , Fitoestrógenos/farmacologia , Pterocarpanos/farmacologia , Animais , Estradiol/metabolismo , Feminino , Humanos , Células MCF-7 , Glândulas Mamárias Animais/citologia , Glândulas Mamárias Animais/metabolismo , Camundongos , Receptores de Estrogênio/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
3.
J Toxicol Environ Health B Crit Rev ; 14(5-7): 300-27, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21790314

RESUMO

Estrogens and estrogen receptors (ER) are key actors in the control of differentiation and survival and act on extrareproductive tissues such as brain. Thus, estrogens may display neuritogenic effects during development and neuroprotective effects in the pathophysiological context of brain ischemia and neurodegenerative pathologies like Alzheimer's disease or Parkinson's disease. Some of these effects require classical transcriptional "genomic" mechanisms through ER, whereas other effects appear to rely clearly on "membrane-initiated mechanisms" through cytoplasmic signal transduction pathways. Disturbances of these mechanisms by endocrine-disrupting chemicals (EDC) may exert adverse effects on brain. Some EDC may act via ER-independent mechanisms but might cross-react with endogenous estrogen. Other EDC may act through ER-dependent mechanisms and display agonistic/antagonistic estrogenic properties. Because of these potential effects of EDC, it is necessary to establish sensitive cell-based assays to determine EDC effects on brain. In the present review, some effects of estrogens and EDC are described with focus on ER-mediated effects in neuronal cells. Particular attention is given to PC12 cells, an interesting model to study the mechanisms underlying ER-mediated differentiating and neuroprotective effects of estrogens.


Assuntos
Encéfalo/efeitos dos fármacos , Disruptores Endócrinos/toxicidade , Estrogênios/farmacologia , Animais , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Modelos Biológicos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Células PC12 , Ratos
4.
Endocrinology ; 150(1): 200-11, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18772239

RESUMO

A precise description of the mechanisms by which estrogen receptor-alpha (ERalpha) exerts its influences on cellular growth and differentiation is still pending. Here, we report that the differentiation of PC12 cells is profoundly affected by ERalpha. Importantly, depending upon its binding to 17beta-estradiol (17betaE2), ERalpha is found to exert different effects on pathways involved in nerve growth factor (NGF) signaling. Indeed, upon its stable expression in PC12 cells, unliganded ERalpha is able to partially inhibit the neurite outgrowth induced by NGF. This process involves a repression of MAPK and phosphatidylinositol 3-kinase/Akt signaling pathways, which leads to a negative regulation of markers of neuronal differentiation such as VGF and NFLc. This repressive action of unliganded ERalpha is mediated by its D domain and does not involve its transactivation and DNA-binding domains, thereby suggesting that direct transcriptional activity of ERalpha is not required. In contrast with this repressive action occurring in the absence of 17betaE2, the expression of ERalpha in PC12 cells allows 17betaE2 to potentiate the NGF-induced neurite outgrowth. Importantly, 17betaE2 has no impact on NGF-induced activity of MAPK and Akt signaling pathways. The mechanisms engaged by liganded ERalpha are thus unlikely to rely on an antagonism of the inhibition mediated by the unliganded ERalpha. Furthermore, 17betaE2 enhances NGF-induced response of VGF and NFLc neuronal markers in PC12 clones expressing ERalpha. This stimulatory effect of 17betaE2 requires the transactivation functions of ERalpha and its D domain, suggesting that an estrogen-responsive element-independent transcriptional mechanism is potentially relevant for the neuritogenic properties of 17betaE2 in ERalpha-expressing PC12 cells.


Assuntos
Divisão Celular/efeitos dos fármacos , Receptor alfa de Estrogênio/genética , Células PC12/citologia , Animais , Células Clonais/citologia , Células Clonais/efeitos dos fármacos , Dietilestilbestrol/farmacologia , Receptor alfa de Estrogênio/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Amplificação de Genes , Variação Genética , Ligantes , Fatores de Crescimento Neural/farmacologia , Neuritos/efeitos dos fármacos , Neuritos/fisiologia , Células PC12/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Ratos , Transcrição Gênica/efeitos dos fármacos
5.
Biochem Biophys Res Commun ; 365(2): 304-9, 2008 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-17991426

RESUMO

The estrogen receptor alpha (ER alpha) is key in regulating normal breast development and function and is closely involved in the onset and progress of cancers. ER alpha transcriptional activity is mediated through two activation functions, AF1 and AF2, whose activity is tightly regulated in a cell-specific manner through yet unknown processes. Here, we demonstrate that cell-cell junctions generate cell permissiveness to AF1 through an up-regulation of the activity of an AF1 sub-region termed box 1. Moreover, the loss of E-cadherin expression is shown to silence the AF1 activity of ER alpha, allowing the receptor to mainly act through its AF2. This switch from an AF1 to an AF2 cell permissiveness also consequently results in the attenuation of ER alpha activity. Therefore, a loss of cell-cell junctions, a key process that occurs during the epithelial-mesenchymal transition, should have a broad impact on ER alpha transcriptional functions.


Assuntos
Caderinas/metabolismo , Receptor alfa de Estrogênio/metabolismo , Furilfuramida/metabolismo , Hepatócitos/metabolismo , Junções Intercelulares/fisiologia , Fatores de Transcrição/metabolismo , Ativação Transcricional/fisiologia , Linhagem Celular , Células HeLa , Humanos
6.
J Radiat Res ; 58(4): 439-445, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-28339776

RESUMO

Several forthcoming wireless telecommunication systems will use electromagnetic frequencies at millimeter waves (MMWs), and technologies developed around the 60-GHz band will soon know a widespread distribution. Free nerve endings within the skin have been suggested to be the targets of MMW therapy which has been used in the former Soviet Union. So far, no studies have assessed the impact of MMW exposure on neuronal metabolism. Here, we investigated the effects of a 24-h MMW exposure at 60.4 GHz, with an incident power density (IPD) of 5 mW/cm², on the dopaminergic turnover of NGF-treated PC12 cells. After MMW exposure, both intracellular and extracellular contents of dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were studied using high performance liquid chromatography. Impact of exposure on the dopamine transporter (DAT) expression was also assessed by immunocytochemistry. We analyzed the dopamine turnover by assessing the ratio of DOPAC to DA, and measuring DOPAC accumulation in the medium. Neither dopamine turnover nor DAT protein expression level were impacted by MMW exposure. However, extracellular accumulation of DOPAC was found to be slightly increased, but not significantly. This result was related to the thermal effect, and overall, no evidence of non-thermal effects of MMW exposure were observed on dopamine metabolism.


Assuntos
Dopamina/metabolismo , Radiação Eletromagnética , Fator de Crescimento Neural/farmacologia , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Animais , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Espaço Extracelular/metabolismo , Células PC12 , Ratos
7.
Endocrinology ; 146(12): 5474-84, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16150902

RESUMO

The expression of two human estrogen receptor-alpha (hERalpha) isoforms has been characterized within estrogen receptor-alpha-positive breast cancer cell lines such as MCF7: the full-length hERalpha66 and the N terminally deleted hERalpha46, which is devoid of activation function (AF)-1. Although hERalpha66 is known to mediate the mitogenic effects that estrogens have on MCF7 cells, the exact function of hERalpha46 in these cells remains undefined. Here we show that, during MCF7 cell growth, hERalpha46 is mainly expressed in the nucleus at relatively low levels, whereas hERalpha66 accumulates in the nucleus. When cells reach confluence, the situation reverses, with hERalpha46 accumulating within the nucleus. Although hERalpha46 expression remains rather stable during an estrogen-induced cell cycle, its overexpression in proliferating MCF7 cells provokes a cell-cycle arrest in G(0)/G(1) phases. To gain further details on the influence of hERalpha46 on cell growth, we used PC12 estrogen receptor-alpha-negative cell line, in which stable transfection of hERalpha66 but not hERalpha46 allows estrogens to behave as mitogens. We next demonstrate that, in MCF7 cells, overexpression of hERalpha46 inhibits the hERalpha66-mediated estrogenic induction of all AF-1-sensitive reporters: c-fos and cyclin D1 as well as estrogen-responsive element-driven reporters. Our data indicate that this inhibition occurs likely through functional competitions between both isoforms. In summary, hERalpha46 antagonizes the proliferative action of hERalpha66 in MCF7 cells in part by inhibiting hERalpha66 AF-1 activity.


Assuntos
Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor alfa de Estrogênio/metabolismo , Ligação Competitiva , Neoplasias da Mama/genética , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Proliferação de Células , Dimerização , Estradiol/farmacologia , Estrogênios , Feminino , Fase G1 , Regulação da Expressão Gênica , Humanos , Elementos de Resposta , Fase de Repouso do Ciclo Celular , Distribuição Tecidual
8.
J Mol Endocrinol ; 35(2): 257-67, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16216907

RESUMO

Numerous studies, both in vivo and in vitro, have reported neuronal differentiating and neuroprotective actions of estrogens. Most of these estrogenic effects are mediated through specific receptors termed estrogen receptors. The aim of this study was to assess the importance of the N-terminal A/B domain of the estrogen receptor-alpha (ER alpha) in its neuronal aspects. Consequently, estrogen effects on (i) the transcriptional activity of target genes, (ii) neuronal differentiation and (iii) neuroprotection in PC12 cells transfected with either a full length form of ER alpha or an A/B domain truncated form (ER alphaCF), have been studied. We demonstrate that the maximal estrogen-induced transcriptional activity of reporter genes requires a full length ER alpha, especially when cells are differentiated. Precisely, the transcriptional activity of ER alpha in differentiated cells relies, predominantly, on the activation function AF-1, located in the A/B domain. Furthermore, in PC12 cells stably expressing ER alpha, 17beta-estradiol markedly enhances the neurite outgrowth triggered by treatment with nerve growth factor and protects cells from oxidative shocks induced by depletion of glutathione. These estrogenic effects are not observed in non-transfected cells and in cells transfected with the truncated ER, devoid of the A/B domain. Altogether, these results underline the importance of the A/B domain of ER alpha in both the differentiating and the neuroprotective effects of estrogens.


Assuntos
Diferenciação Celular/fisiologia , Estradiol/metabolismo , Receptor alfa de Estrogênio/química , Receptor alfa de Estrogênio/metabolismo , Neurônios/fisiologia , Fármacos Neuroprotetores/metabolismo , Células PC12 , Animais , Butionina Sulfoximina/metabolismo , Inibidores Enzimáticos/metabolismo , Estradiol/análogos & derivados , Receptor alfa de Estrogênio/genética , Regulação da Expressão Gênica , Genes Reporter , Humanos , Neurônios/citologia , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Estrutura Terciária de Proteína , Ratos , Transcrição Gênica
9.
J Comp Neurol ; 449(4): 374-89, 2002 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-12115673

RESUMO

This report describes the distribution of tyrosine hydroxylase (TH)-expressing structures in the brain of rainbow trout (Oncorhynchus mykiss). TH neurons have been localized by the use of two complementary techniques, immunocytochemistry and in situ hybridization of TH messenger RNA. Results obtained from in situ hybridization and immunocytochemistry were in agreement. TH cells were observed in many areas of the brain, with a higher density at the level of the olfactory bulbs where TH-positive neurons are abundant in the internal cell layer. In the telencephalon, two populations of TH neurons can be distinguished: one group is located in the area ventralis telencephali pars dorsalis, and the other group is located in the area ventralis telencephali pars ventralis and extends laterally in the area ventralis telencephali pars lateralis. Many labeled neurons are also seen in the preoptic area as well as in the hypothalamus, where several clusters of TH-positive cells are observed. Some of these neurons located in the paraventricular organ grow a short cytoplasmic extension directed to the ventricular wall and are known to be cerebrospinal fluid-contacting cells. The most caudal TH neurons are observed at the level of the locus caeruleus. At the level of the pituitary, TH-positive fibers are observed in the neurohypophysis. The TH-immunoreactive innervation at the level of the pituitary provides a neuroanatomic basis for the effects of dopamine and/or norepinephrine on the release of pituitary hormones in fish.


Assuntos
Química Encefálica , Encéfalo/enzimologia , RNA Mensageiro/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Animais , Encéfalo/citologia , Química Encefálica/genética , Química Encefálica/fisiologia , Tronco Encefálico/química , Tronco Encefálico/citologia , Tronco Encefálico/enzimologia , Diencéfalo/química , Diencéfalo/citologia , Diencéfalo/enzimologia , Feminino , Imuno-Histoquímica , Hibridização In Situ , Neurônios/química , Neurônios/citologia , Neurônios/enzimologia , Oncorhynchus mykiss , RNA Mensageiro/biossíntese , Telencéfalo/química , Telencéfalo/citologia , Telencéfalo/enzimologia , Tirosina 3-Mono-Oxigenase/biossíntese
10.
J Comp Neurol ; 458(1): 32-45, 2003 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-12577321

RESUMO

The distribution of D(2)R (dopamine D(2) receptor) mRNAs was studied in the forebrain of maturing female rainbow trout by means of in situ hybridization using a (35)S-labeled riboprobe (810 bp) spanning the third intracytoplasmic loop. A hybridization signal was consistently obtained in the olfactory epithelium, the internal cell layer of the olfactory bulbs, the ventral and dorsal subdivisions of the ventral telencephalon, and most preoptic subdivisions, with the notable exception of the magnocellular preoptic nucleus, and the periventricular regions of the mediobasal hypothalamus, including the posterior tuberculum. In the pituitary, the signal was higher in the pars intermedia than in the proximal and the rostral pars distalis, but no obvious correspondence with a given cell type could be assigned. Labeled cells were also located in the thalamic region, some pretectal nuclei, the optic tectum, and the torus semicircularis. These results provide a morphologic basis for a better understanding on the functions and evolution of the dopaminergic systems in lower vertebrates.


Assuntos
Hibridização In Situ , Oncorhynchus mykiss , Hipófise/química , Prosencéfalo/química , Receptores de Dopamina D2/análise , Animais , Feminino , RNA Mensageiro/análise , Receptores de Dopamina D2/genética
11.
Environ Toxicol Chem ; 21(1): 175-81, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11804052

RESUMO

The effects of concentration (5, 50, and 500 microg/L) and duration (24, 48 h) of exposure to carbofuran, a carbamate insecticide, were assessed on brain catecholamine (norepinephrine [NE] and dopamine), plasma glucose, and hepatic glycogen contents and behavioral activities of goldfish (Carassius auratus). After 24 h of exposure to 50 and 500 microg/L, the level of NE was increased in the olfactory bulbs. The same effect was observed after a 48-h exposure to 500 and 50 microg/L in the telencephalic hemispheres and in the hypothalamus, respectively. An increase in the level of dopamine was also found in hypothalamus after 48 h of exposure to 500 microg/L carbofuran. Plasma glucose increased in concentration after both periods of exposure to carbofuran at 50 and 500 microg/L. Hepatic glycogen concentration decreased after a 48-h exposure to the highest concentration. Behavioral endpoints related to swimming pattern and social interactions were affected after a 24-h exposure to the lowest concentration tested (5 microg/L). The relative sensitivities of these different types of responses to exposure to carbofuran are discussed in light of data on the neurotoxic effects of carbamate and organophosphate insecticides in fish.


Assuntos
Comportamento Animal/efeitos dos fármacos , Química Encefálica/efeitos dos fármacos , Carbofurano/toxicidade , Carpa Dourada/metabolismo , Inseticidas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Glicemia/metabolismo , Dopamina/metabolismo , Carpa Dourada/sangue , Glicogênio Hepático/metabolismo , Norepinefrina/metabolismo , Fatores de Tempo
12.
Chemosphere ; 112: 240-7, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25048912

RESUMO

Xeno-estrogens, a class of endocrine disrupting chemicals (EDCs), can disturb estrogen receptor-dependent pathways involved in differentiation, proliferation or protection. Multiple methods have been developed to characterize the disturbances induced by EDCs in different cells or organs. In this study we have developed a new tool for the assessment of estrogenic compounds on differentiation. For this purpose we used the global model of NGF-induced neurite outgrowth of a pseudoneuronal PC12 cell line stably transfected with estrogen receptor alpha (PC12 ER). This new test evidences a new selectivity in which estradiol, genistein and 4-hydroxytamoxifen increased the NGF-induced neurite outgrowth of PC12 ER cells in a dose-dependent manner. In contrast, the strong estrogen agonist 17α-ethynylestradiol, the strong antagonist raloxifene and the agonist bisphenol A were unable to modify the neuritogenesis of PC12 ER cells. Therefore, the analysis of neuritogenesis in PC12 ER cells constitutes a complementary tool for the characterization of xeno-estrogen activity and also serves as a basis for further studies focusing on the mechanisms of EDCs in a neuronal context. Moreover, this test constitutes an alternative to animal testing.


Assuntos
Bioensaio/métodos , Diferenciação Celular/efeitos dos fármacos , Disruptores Endócrinos/toxicidade , Receptor alfa de Estrogênio/metabolismo , Estrogênios/toxicidade , Testes de Toxicidade/métodos , Animais , Expressão Gênica , Neuritos/efeitos dos fármacos , Neuritos/metabolismo , Células PC12 , Ratos
13.
PLoS One ; 8(6): e69081, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23825704

RESUMO

Many studies have reported proliferative, differentiating or protective effects of estradiol, notably through estrogen receptor alpha (ERα). On the contrary, the ligand-independent action of ERα is currently poorly documented notably in cell protection. The stable transfection of wild type, substituted or truncated form of ERα in PC12 cells (ERα negative cell line) lead the specific study of its ligand-independent action. Hence, we demonstrate here that, in the absence of E2, the expression of ERα prevents cells from apoptosis induced by serum deprivation. This protection is not due to an ERE-mediated transcription and does not require either AF-1 or AF-2 transactivation functions. It is afforded to the Y537 residue of ERα and activation of c-Src/Stat3 signaling pathway.


Assuntos
Receptor alfa de Estrogênio/metabolismo , Soro/metabolismo , Animais , Apoptose , Sobrevivência Celular , Receptor alfa de Estrogênio/química , Humanos , Ligantes , Células MCF-7 , Células PC12 , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Ratos , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais , Tirosina/metabolismo
14.
Biol Reprod ; 73(4): 703-12, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15944240

RESUMO

Testicular descent corresponds to migration of the testis from the abdominal cavity to the scrotum and is essential for proper functioning of the testis. Recent advances in the characterization of estrogen receptor (ESR) subtypes and isoforms in various tissues prompted us to study ESRs within the gubernaculum testis, a structure involved in testicular descent. In the rat gubernaculum, we searched for ESR alpha (Esr1) and beta (Esr2) and for the androgen receptor (Ar), androgens being known to regulate testicular descent. Reverse transcription-polymerase chain reaction (RT-PCR) revealed that Esr1, Esr2, and Ar mRNAs were all expressed in the gubernaculum. Using PEETA (Primer extension, Electrophoresis, Elution, Tailing, and Amplification), we established that all Esr1 leader exons, previously identified in other organs, such as the uterus and pituitary, were transcribed in the gubernaculum, with the major form being O/B. The RNA protection assays, RT-PCR, and Western blot experiments revealed that isoform-specific mRNA transcripts generated by alternative splicing of the C-leader sequence on coding exons 1 and 2 of the Esr1 gene gave the 46- and 66-kDa ESR1 proteins. The ESR1 and AR proteins were found to colocalize in the parenchymal cells of the gubernaculum early in development, whereas AR also was strongly expressed in the muscular cells, both during fetal and postnatal life. The ESR2 protein was weakly expressed, principally in the muscular cells, but only once testicular descent had occurred. The levels of the 46-kDa ESR1 variant (ER46) exceeded those of the 66-kDa ESR1 form (ER66) at periods when the gubernaculum developed. Conversely, the 66-kDa form appears to predominate clearly when the gubernaculum growth was low or completed. The possible role of estrogens on the modulation of the androgen-dependent growth of the gubernaculum and, more widely, on testicular descent is discussed.


Assuntos
Receptor alfa de Estrogênio/genética , Regulação da Expressão Gênica no Desenvolvimento , Testículo/embriologia , Testículo/metabolismo , Processamento Alternativo , Animais , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/genética , Receptor beta de Estrogênio/metabolismo , Feminino , Masculino , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo
15.
Gen Comp Endocrinol ; 127(2): 198-206, 2002 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-12383448

RESUMO

The role of sexual steroids in the modulation of a dopaminergic inhibitory tone on FSH and LH release was studied in the rainbow trout. The experiments were performed on previtellogenic trout, implanted or not with estradiol (E(2)), and vitellogenic trout. E(2) implant increased the circulating levels of LH and decreased the circulating levels of FSH in previtellogenic fish. The catecholamine inhibitor alphaMPT increased the circulating levels of LH, implanted or not with E(2). AlphaMPT increased circulating levels of LH in vitellogenic fish. This increase could be prevented by the dopaminergic agonist bromocryptine. The dopaminergic drugs had no effect on the circulating levels of FSH in all groups. E(2) decreased mRNA levels of sGnRH1 and sGnRH2 in the telencephalon of previtellogenic fish. The dopaminergic treatments had no effect on mRNA levels of both forms of sGnRH in previtellogenic and vitellogenic fish. Primary cultures of pituitary cells were primed for three days with steroids (E(2) or 17alpha-hydroxy, 20beta-dihydroprogesterone (17alpha20betaP)) before treatment with increasing doses of bromocryptine, associated or not with sGnRH. E(2), but not 17alpha20betaP, potentiated the sGnRH-induced release of LH. Bromocryptine induced a slight dose-dependent decrease of sGnRH-induced release of LH. This decrease was potentiated by 17alpha20betaP. E(2) and 17alpha20betaP had no effect on the release of FSH, but bromocryptine decreased the 10(-8)M sGnRH-induced release of FSH. In conclusion, the development of the dopaminergic inhibitory tone on gonadotropin release, at the onset of vitellogenesis, requires factors other than estradiol. E(2) should contribute in part to decrease the release of FSH. At the end of the reproductive cycle, 17alpha20betaP should reinforce the dopaminergic inhibitory tone.


Assuntos
Hormônio Foliculoestimulante/metabolismo , Hormônios Esteroides Gonadais/fisiologia , Hormônio Luteinizante/metabolismo , Oncorhynchus mykiss/metabolismo , Hipófise/metabolismo , Receptores de Dopamina D2/metabolismo , Animais , Química Encefálica/fisiologia , Bromocriptina/farmacologia , Células Cultivadas , DNA Complementar/metabolismo , Dopamina/metabolismo , Agonistas de Dopamina/farmacologia , Relação Dose-Resposta a Droga , Estradiol/farmacologia , Feminino , Hormônio Liberador de Gonadotropina/farmacologia , Hidroxiprogesteronas/farmacologia
16.
J Biol Chem ; 279(25): 26184-91, 2004 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-15078875

RESUMO

The activity of the transactivation functions (activation function (AF)-1 and AF-2) of the estrogen receptor alpha (ERalpha) is cell-specific. This study aimed to decipher the yet unclear mechanisms involved in this differential cell sensitivity, with particular attention to the specific influence that cell differentiation may have on these processes. Hence, we comparatively evaluated the permissiveness of cells to either ERalpha AFs in two different cases: (i) a series of cell lines originating from a common tissue, but with distinct differentiation phenotypes; and (ii) cell lines that undergo differentiation processes in culture. These experiments demonstrate that the respective contribution that AF-1 and AF-2 make toward ERalpha activity varies in a cell differentiation stage-dependent manner. Specifically, whereas AF-1 is the dominant AF involved in ERalpha transcriptional activity in differentiated cells, the more a cell is de-differentiated the more this cell mediates ERalpha signaling through AF-2. For instance, AF-2 is the only active AF in cells that have achieved their epithelial-mesenchymal transition. Moreover, the stable expression of a functional ERalpha in strictly AF-2 permissive cells restores an AF-1-sensitive cell context. These results, together with data obtained in different ERalpha-positive cell lines tested strongly suggest that the transcriptional activity of ERalpha relies on its AF-1 in most estrogen target cell types.


Assuntos
Receptores de Estrogênio/química , Transcrição Gênica , Animais , Western Blotting , Diferenciação Celular , Linhagem Celular , Linhagem Celular Tumoral , Linhagem da Célula , Receptor alfa de Estrogênio , Células HeLa , Humanos , Luciferases/metabolismo , Fenótipo , Plasmídeos/metabolismo , Estrutura Terciária de Proteína , Receptores de Estrogênio/metabolismo , Fatores de Tempo , Transfecção
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