RESUMO
The enzyme 11beta-hydroxysteroid dehydrogenase (HSD) type 1 converts inactive cortisone into active cortisol in cells, thereby raising the effective glucocorticoid (GC) tone above serum levels. We report that pharmacologic inhibition of 11beta-HSD1 has a therapeutic effect in mouse models of metabolic syndrome. Administration of a selective, potent 11beta-HSD1 inhibitor lowered body weight, insulin, fasting glucose, triglycerides, and cholesterol in diet-induced obese mice and lowered fasting glucose, insulin, glucagon, triglycerides, and free fatty acids, as well as improved glucose tolerance, in a mouse model of type 2 diabetes. Most importantly, inhibition of 11beta-HSD1 slowed plaque progression in a murine model of atherosclerosis, the key clinical sequela of metabolic syndrome. Mice with a targeted deletion of apolipoprotein E exhibited 84% less accumulation of aortic total cholesterol, as well as lower serum cholesterol and triglycerides, when treated with an 11beta-HSD1 inhibitor. These data provide the first evidence that pharmacologic inhibition of intracellular GC activation can effectively treat atherosclerosis, the key clinical consequence of metabolic syndrome, in addition to its salutary effect on multiple aspects of the metabolic syndrome itself.
Assuntos
11-beta-Hidroxiesteroide Desidrogenase Tipo 1/antagonistas & inibidores , Adamantano/análogos & derivados , Arteriosclerose/tratamento farmacológico , Azepinas/administração & dosagem , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/administração & dosagem , Resistência à Insulina , Triazóis/administração & dosagem , 11-beta-Hidroxiesteroide Desidrogenase Tipo 1/metabolismo , Adamantano/administração & dosagem , Animais , Aorta/metabolismo , Arteriosclerose/complicações , Arteriosclerose/enzimologia , Glicemia/efeitos dos fármacos , Cortisona/metabolismo , Dieta Aterogênica , Modelos Animais de Doenças , Ácidos Graxos/sangue , Hidrocortisona , Insulina/sangue , Masculino , Camundongos , Camundongos Endogâmicos ICR , Camundongos Knockout , Síndrome , Triglicerídeos/sangueRESUMO
Somatostatin inhibits both glucagon and insulin secretion. Glucagon significantly contributes to hyperglycemia in type 2 diabetes. Despite its function in the inhibition of glucagon secretion, somatostatin fails to reduce hyperglycemia in type 2 diabetes, due to a parallel suppression of insulin secretion. Five pharmacologically distinct somatostatin receptor subtypes (sst(1)-sst(5)) mediate the effects of somatostatin on a cellular level. Pancreatic A cells express sst(2), whereas B cells express sst(5). In this study, we describe a novel approach to the treatment of type 2 diabetes using a highly sst(2)-selective, nonpeptide agonist (compound 1). Compound 1 effectively inhibited glucagon secretion from pancreatic islets isolated from wild-type mice, whereas glucagon secretion from sst(2)-deficient islets was not suppressed. Compound 1 did not influence nonfasted insulin concentration. In sst(2)-deficient mice, compound 1 did not have any effects on glucagon or glucose levels, confirming its sst(2) selectivity. In animal models of type 2 diabetes in the nonfasted state, circulating glucagon and glucose levels were decreased after treatment with compound 1. In the fasting state, compound 1 lowered blood glucose by approximately 25%. In summary, small-molecule sst(2)-selective agonists that suppress glucagon secretion offer a novel approach toward the development of orally bioavailable drugs for treatment of type 2 diabetes.
Assuntos
Hipoglicemiantes/farmacologia , Receptores de Somatostatina/agonistas , Animais , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Cães , Glucagon/metabolismo , Hormônio do Crescimento/metabolismo , Técnicas In Vitro , Insulina/metabolismo , Insulina/farmacologia , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Obesos , Ratos , Receptores de Somatostatina/genéticaRESUMO
BACKGROUND: Distinct expression patterns of estrogen receptor (ER)-alpha and ER-beta are displayed in the murine central nervous system. ER-beta is the predominant form of the receptor expressed in the murine midbrain dorsal raphe nucleus (DRN). Tryptophan hydroxylase (TPH) is abundantly expressed in the serotonergic neurons of the DRN and is regulated by estrogen in both the monkey and the guinea pig. METHODS: In this study we used immunocytochemistry to show that ER-beta and TPH are colocalized in the serotonergic cells of the murine DRN. We utilized the ER-alpha and ER-beta gene deletion mouse models and in situ hybridization to demonstrate that ER-beta is responsible for regulating TPH1 mRNA expression. RESULTS: Estrogen increased TPH1 mRNA expression in the DRN of wild type and ER-alpha knockout mice (alpha-ERKO) but not ER-beta knockouts (beta-ERKO). CONCLUSIONS: These data indicate that ER-beta is responsible for mediating estrogen regulated TPH1 expression in the murine DRN.
Assuntos
Receptor beta de Estrogênio/fisiologia , Mesencéfalo/metabolismo , Núcleos da Rafe/metabolismo , Triptofano Hidroxilase/biossíntese , Animais , Células Cultivadas , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/fisiologia , Receptor beta de Estrogênio/genética , Imuno-Histoquímica , Hibridização In Situ , Mesencéfalo/enzimologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Ovariectomia , Núcleos da Rafe/enzimologia , Serotonina/fisiologiaRESUMO
RATIONALE: The decrease in levels of estrogens (ER) that occurs in menopause has been correlated with depressive disorders, probably due to ER direct and/or indirect effects in the brain, where these hormones act through both genomic (i.e. interaction as transcription factors with nuclear receptors ER-alpha and ER-beta) and non-genomic (i.e. binding with cell-membrane receptors) mechanisms. With respect to mood related disorders the interaction between ER-beta and the serotonin (5-HT) system is highly relevant. 17beta-Estradiol (E2) induces expression of the enzyme implicated in 5-HT synthesis - tryptophan hydroxylase (TPH), and this effect is mediated through ER-beta located in 5-HT cell bodies of the dorsal raphe nucleus (DRN). OBJECTIVE: The present studies tested the hypothesis that E2 induces antidepressant-like effects in female ovariectomized (OVX) mice, and that expression of ER-beta is mandatory for such effects. METHODS: The Forced Swim Test (FST) was used in three experiments to assess (a) dose response effect of E2 in outbred and inbred mouse strains, (b) length of treatment necessary for effect, (c) and role of ER-beta receptors. RESULTS: E2 (100 or 200 microg/kg), as well as the antidepressant desipramine (DMI), significantly reduced total duration of immobility in the FST in mice from different strains. Four consecutive daily doses (200 microg/kg) were required for such effect, which was absent in mice lacking the gene coding for ER-beta (BERKO mice). CONCLUSION: These data suggest that E2-induced antidepressant-like effects in mice are mediated through activation of ER-beta. They offer preliminary support to the hypothesis that specific compounds acting at ER-beta may influence mood in postmenopausal women.
Assuntos
Antidepressivos/uso terapêutico , Transtorno Depressivo/tratamento farmacológico , Estradiol/uso terapêutico , Receptor beta de Estrogênio/deficiência , Receptor beta de Estrogênio/genética , Natação , Animais , Antidepressivos/farmacologia , Transtorno Depressivo/genética , Transtorno Depressivo/metabolismo , Estradiol/farmacologia , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ovariectomia , Natação/psicologiaRESUMO
Somatostatin (SRIF) regulates pancreatic insulin and glucagon secretion. In the present study we describe the generation of SRIF receptor subtype 5 knockout (sst(5) KO) mice to examine the role of SRIF receptor subtypes (sst) in regulating insulin secretion and glucose homeostasis. Mice deficient in sst(5) were viable, fertile, appeared healthy, and displayed no obvious phenotypic abnormalities. Pancreatic islets isolated from sst(5) KO mice displayed increased total insulin content as compared with islets obtained from wild-type (WT) mice. Somatostatin-28 (SRIF-28) and the sst(5)/sst(1)-selective agonist compound 5/1 potently inhibited glucose-stimulated insulin secretion from WT islets. SRIF-28 inhibited insulin secretion from sst(5) KO islets with 16-fold less potency while the maximal effect of compound 5/1 was markedly diminished when compared with its effects in WT islets. sst(5) KO mice exhibited decreased blood glucose and plasma insulin levels and increased leptin and glucagon concentrations compared with WT mice. Furthermore, sst(5) KO mice displayed decreased susceptibility to high fat diet-induced insulin resistance. The results of these studies suggest sst(5) mediates SRIF inhibition of pancreatic insulin secretion and contributes to the regulation of glucose homeostasis and insulin sensitivity. Our findings suggest a potential beneficial role of sst(5) antagonists for alleviating metabolic abnormalities associated with obesity and insulin resistance.
Assuntos
Glucose/metabolismo , Insulina/metabolismo , Receptores de Somatostatina/fisiologia , Animais , Células CHO , Clonagem Molecular/métodos , Cricetinae , Feminino , Marcação de Genes/métodos , Homeostase/fisiologia , Resistência à Insulina/fisiologia , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Masculino , Camundongos , Camundongos Knockout , Técnicas de Cultura de Órgãos , Receptores de Somatostatina/agonistas , Receptores de Somatostatina/deficiência , Receptores de Somatostatina/genética , Somatostatina/metabolismo , Somatostatina-28 , TransfecçãoRESUMO
Estrogen receptors are important for the development and maintenance of many different tissues in the body including the breast, uterus, brain and bone. There are two known genes encoding estrogen receptors, Estrogen Receptor alpha (ER alpha) and Estrogen Receptor beta (ER beta). These receptors are transcription factors with distinct functional domains involved in DNA binding, ligand binding and transcriptional regulation. A novel isoform of human ER beta (ER beta 548) which includes an extended amino terminal domain has been identified. Isoform specific antibodies confirm the presence of this receptor in human tissue. Transactivation analysis with different estrogenic ligands indicates that ER beta 548 is functionally distinct from previously reported forms of ER beta.
Assuntos
Receptores de Estrogênio/genética , Western Blotting , Códon/genética , Primers do DNA , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Receptor beta de Estrogênio , Genes Reporter/genética , Humanos , Isomerismo , Masculino , Receptores de Estrogênio/efeitos dos fármacos , Receptores de Estrogênio/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Testículo/metabolismo , Ativação TranscricionalRESUMO
Estrogen receptor alpha (ER alpha) and ER beta are members of the steroid nuclear receptor family that modulate gene transcription in an estrogen-dependent manner. ER mRNA and protein have been detected both peripherally and in the central nervous system, with most data having come from the rat. Here we report the development of an ER beta-selective antibody that cross-reacts with mouse, rat, and human ER beta protein and its use to determine the distribution of ER beta in the murine brain. Further, a previously characterized polyclonal antibody to ER alpha was used to compare the distribution of the two receptors in the first comprehensive description of ER distribution specifically in the mouse brain. ER beta immunoreactivity (ir) was primarily localized to cell nuclei within select regions of the brain, including the olfactory bulb, cerebral cortex, septum, preoptic area, bed nucleus of the stria terminalis, amygdala, paraventricular hypothalamic nucleus, thalamus, ventral tegmental area, substantia nigra, dorsal raphe, locus coeruleus, and cerebellum. Extranuclear-ir was detected in several areas, including fibers of the olfactory bulb, CA3 stratum lucidum, and CA1 stratum radiatum of the hippocampus and cerebellum. Although both receptors were generally expressed in a similar distribution through the brain, nuclear ER alpha-ir was the predominant subtype in the hippocampus, preoptic area, and most of the hypothalamus, whereas it was sparse or absent from the cerebral cortex and cerebellum. Collectively, these findings demonstrate the region-selective expression of ER beta and ER alpha in the adult ovariectomized mouse brain. These data provide an anatomical framework for understanding the mechanisms by which estrogen regulates specific neural systems in the mouse.
Assuntos
Encéfalo/metabolismo , Receptores de Estrogênio/metabolismo , Sequência de Aminoácidos/genética , Animais , Células COS , Linhagem Celular , Receptor alfa de Estrogênio , Receptor beta de Estrogênio , Feminino , Humanos , Técnicas Imunológicas , Insetos , Camundongos , Dados de Sequência Molecular , Coelhos , Ratos , Receptores de Estrogênio/genética , Homologia de Sequência de Aminoácidos , Distribuição TecidualRESUMO
The discovery and synthesis of dihydrobenzoxathiins as potent, ERalpha subtype selective ligands are described. The most active analogue, 4-D, was found to be 50-fold selective in a competitive binding assay and 100-fold selective in a transactivation assay in HEK-293 cells. The alpha selectivity was postulated to lie in the interaction of the sulfur atom of the benzoxathiin ring with the two discriminating residues in the binding pocket of the receptor isoforms.
Assuntos
Oxati-Inas/síntese química , Moduladores Seletivos de Receptor Estrogênico/síntese química , Animais , Sítios de Ligação , Ligação Competitiva , Linhagem Celular , Cristalografia por Raios X , Receptor alfa de Estrogênio , Receptor beta de Estrogênio , Feminino , Humanos , Ligantes , Modelos Moleculares , Conformação Molecular , Tamanho do Órgão/efeitos dos fármacos , Oxati-Inas/química , Oxati-Inas/farmacologia , Receptores de Estrogênio/efeitos dos fármacos , Receptores de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Ativação Transcricional , Útero/efeitos dos fármacosRESUMO
Estrogen action is mediated via two estrogen receptor (ER) subtypes, ERalpha and ERbeta. Selective ER modulators with balanced high affinity for ERalpha and ERbeta have been developed as therapeutics for the treatment of a variety of diseases, including hormone-responsive breast cancer and osteoporosis. Recent data based primarily on the evaluation of ER-knockout mice have revealed that ERalpha and ERbeta may regulate separate and distinct biological processes. The identification of ERbeta specific ligands could further enhance our understanding of ERbeta biology. In addition, compounds targeting ERbeta may prove useful as therapeutic agents with activity profiles distinguishable from that of estradiol. To discover novel selective ligands for ERbeta, we developed and characterized a cell-based Gal4-ERbeta beta-lactamase reporter gene assay (GERTA) in CHO cells for the ligand-induced activation of the human ERbeta. The sensitivity and selectivity of this assay were found to be comparable to those of an ER ligand-binding assay. The assay was optimized for screening in an ultra high throughput 3456-well nanoplate format and was successfully used to screen a large compound collection for ERbeta agonists. Compounds identified in a primary screen were tested in an in vitro ligand-binding assay to characterize further the selectivity and potency for ERbeta.
Assuntos
Nanotecnologia/métodos , Receptores de Estrogênio/agonistas , Receptores de Estrogênio/metabolismo , Fatores de Transcrição/metabolismo , Ativação Transcricional/fisiologia , beta-Lactamases/metabolismo , Animais , Células CHO , Cricetinae , Relação Dose-Resposta a Droga , Estradiol/metabolismo , Estradiol/farmacologia , Receptor beta de Estrogênio , Vetores Genéticos , Humanos , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Receptores de Estrogênio/genética , Fatores de Transcrição/genética , beta-Lactamases/genéticaRESUMO
BACKGROUND: Bisphenol A (BPA) and other related chemical compounds may be components used in the manufacturing process of resin-based composite dental restorative material. The purpose of the authors' study was to assess salivary and urinary concentrations of BPA and other compounds before and after placement of resin-based composite dental restorations. METHODS: The authors collected saliva and urine from 172 participants receiving composite restorations before and as long as 30 hours after placement of composite restorations. The authors analyzed saliva specimens from 151 participants and urine specimens from 171 participants for concentrations of BPA and five related compounds by using liquid chromatography/mass spectrometry (LC/MS). RESULTS: Salivary concentrations of BPA and some related compounds increased immediately (within one hour) after composite placement. Salivary concentrations of BPA and most study compounds returned to prerestoration levels within eight hours after composite placement. With the exception of a 43 percent increase in BPA, concentrations of the study compounds in urine returned to prerestoration levels nine to 30 hours after restoration placement. Concentrations in saliva were lower when a rubber dam was used; however, rubber dam use appeared to have no effect on urinary concentrations of the measured compounds during the study period. The authors observed similar changes in study compound levels in both saliva and urine between participants who received anterior restorations and those who received posterior restorations. CONCLUSIONS: Placement of resin-based composite restorations was associated with detectable increases in saliva of BPA and other study compounds within one hour after restoration placement and an increased concentration of BPA in urine nine to 30 hours after restoration placement. Rubber dam use did not reduce the absorption of BPA (measured as BPA level in urine) during the study. CLINICAL IMPLICATIONS: Additional studies are needed to address how long BPA levels in urine associated with composite placement remain elevated to aid in better understanding of the clearance rates of BPA and other study compounds.
Assuntos
Compostos Benzidrílicos/análise , Resinas Compostas/análise , Materiais Dentários/análise , Restauração Dentária Permanente , Fenóis/análise , Saliva/química , Resinas Acrílicas/química , Adulto , Compostos Benzidrílicos/química , Compostos Benzidrílicos/urina , Cromatografia Líquida , Resinas Compostas/química , Materiais Dentários/química , Compostos de Epóxi/análise , Feminino , Seguimentos , Humanos , Masculino , Espectrometria de Massas , Metacrilatos/análise , Fenóis/química , Fenóis/urina , Polietilenoglicóis/análise , Ácidos Polimetacrílicos/análise , Poliuretanos/química , Diques de BorrachaRESUMO
OBJECTIVE: To test the role of ERbeta in the control of estrogen-dependent thermoregulation in rats. METHODS: Test the ability of an ERbeta-selective ligand to suppress the elevation in basal rat tail skin temperature (TST) caused by ovariectomy (OVX). RESULTS: ERbeta-19 is a tetrahydrofluorenone ERbeta-selective ligand that displaces 0.1 nM estradiol from ERbeta with an IC50 of 1.8 nM compared to an IC50 of 141 nM for ERalpha. Like estradiol, it acts as an agonist on ERbeta-mediated transactivation and transrepression with 25- and 60-fold selectivity, respectively, over ERalpha-controlled transcription. Administration of estradiol to estrogen-depleted rats suppresses the ovariectomy-induced elevation of TST. Similar treatment of OVX rats with ERbeta-19 also results in suppression of elevated TST. However, in contrast to estradiol, ERbeta-19 does not suppress body weight, does not increase uterine weight, nor does it stimulate uterocalin biomarker expression which is under the control of ERalpha. Thus, the ERbeta-19 suppression of rat TST is mediated by ERbeta without eliciting the activity of ERalpha. CONCLUSION: Estrogen-sensitive thermoregulation in ovariectomized rats can be controlled by an ERbeta-selective ligand.
Assuntos
Regulação da Temperatura Corporal/genética , Estradiol/farmacologia , Receptor beta de Estrogênio/agonistas , Fluorenos/farmacologia , Temperatura Cutânea/genética , Animais , Regulação da Temperatura Corporal/fisiologia , Peso Corporal/efeitos dos fármacos , Estradiol/genética , Estradiol/metabolismo , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/genética , Receptor beta de Estrogênio/metabolismo , Feminino , Regulação da Expressão Gênica , Ligantes , Lipocalinas/metabolismo , Tamanho do Órgão/efeitos dos fármacos , Ovariectomia , Ratos , Ratos Sprague-Dawley , Temperatura Cutânea/fisiologia , Cauda , Útero/metabolismoRESUMO
A novel class of indole ligands for estrogen receptor alpha have been discovered which exhibit potent affinity and high selectivity. Substitution of the bazedoxifene skeleton to the linker present in the HTS lead 1a provided 22b which was found to be 130-fold alpha-selective and acted as an antagonist of estradiol activity in uterine tissue and MCF-7 cancer cells.
Assuntos
Receptor alfa de Estrogênio/antagonistas & inibidores , Indóis/química , Indóis/farmacocinética , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Antagonistas de Estrogênios/química , Antagonistas de Estrogênios/farmacologia , Feminino , Humanos , Concentração Inibidora 50 , Ligantes , Útero/efeitos dos fármacosRESUMO
The ring oxygen and sulfur analogs of lasofoxifene, 1a and 1b, were synthesized in an attempt to impart ERalpha selectivity, as found in the closely related dihydrobenzoxathiin compound I, recently discovered in these laboratories. The resulting isochroman and isothiochroman compounds were found to exhibit equipotent binding affinities to the ER isoforms and were less active in the inhibition of estradiol-triggered uterine growth when compared to I and lasofoxifene.
Assuntos
Cromanos/síntese química , Cromanos/farmacologia , Receptor alfa de Estrogênio/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Estradiol/farmacologia , Feminino , Humanos , Concentração Inibidora 50 , Ligantes , Modelos Moleculares , Ligação Proteica , Isoformas de Proteínas , Relação Estrutura-Atividade , Útero/efeitos dos fármacos , Útero/crescimento & desenvolvimentoRESUMO
A series of dihydrobenzoxathiin SERAMs with alkylated pyrrolidine side chains or alkylated linkers was prepared. Minor modifications in the side chain or linker resulted in significant effects on biological activity, especially in uterine tissue.
Assuntos
Oxati-Inas/farmacologia , Pirrolidinas/química , Receptores de Estrogênio/efeitos dos fármacos , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Ligantes , Modelos Moleculares , Oxati-Inas/química , Receptores de Estrogênio/metabolismoRESUMO
Adamantyl triazoles were identified as selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). They are active both in in vitro and in in vivo pharmacodynamic models. The synthesis and structure-activity relationships of these inhibitors are presented.
Assuntos
11-beta-Hidroxiesteroide Desidrogenase Tipo 1/antagonistas & inibidores , Inibidores Enzimáticos/síntese química , Triazóis/síntese química , Adamantano/síntese química , Adamantano/farmacocinética , Adamantano/farmacologia , Animais , Inibidores Enzimáticos/farmacocinética , Inibidores Enzimáticos/farmacologia , Humanos , Concentração Inibidora 50 , Síndrome Metabólica/tratamento farmacológico , Camundongos , Farmacocinética , Relação Estrutura-Atividade , Triazóis/farmacocinética , Triazóis/farmacologiaRESUMO
An optimized side chain for dihydrobenzoxathiin SERAMs was discovered and attached to four dihydrobenzoxathiin platforms. The novel SERAMs show exceptional estrogen antagonist activity in uterine tissue and an MCF-7 breast cancer cell assay.
Assuntos
Oxati-Inas/síntese química , Receptores de Estrogênio/química , Moduladores Seletivos de Receptor Estrogênico/síntese química , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Antagonistas de Estrogênios/síntese química , Antagonistas de Estrogênios/farmacologia , Feminino , Humanos , Oxati-Inas/farmacologia , Ratos , Receptores de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Relação Estrutura-Atividade , Útero/efeitos dos fármacos , Útero/crescimento & desenvolvimentoRESUMO
The discovery, synthesis, and SAR of chromanes as ER alpha subtype selective ligands are described. X-ray studies revealed that the origin of the ER alpha-selectivity resulted from a C-4 trans methyl substitution to the cis-2,3-diphenyl-chromane platform. Selected compounds from this class demonstrated very potent in vivo antagonism of estradiol in an immature rat uterine weight assay, effectively inhibited ovariectomy-induced bone resorption in a 42 days treatment paradigm, and lowered serum cholesterol levels in ovx'd adult rat models. The best antagonists 8F and 12F also exhibited potent inhibition of MCF-7 cell growth and were shown to be estrogen receptor down-regulators (SERDs).
Assuntos
Cromanos/química , Cromanos/farmacologia , Receptor alfa de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Animais , Sítios de Ligação , Linhagem Celular , Feminino , Expressão Gênica/efeitos dos fármacos , Humanos , Ligantes , Modelos Químicos , Estrutura Molecular , Tamanho do Órgão , Ligação Proteica , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Útero/efeitos dos fármacosRESUMO
The critical steps in bile acid metabolism have remarkable differences between humans and mice. It is known that human cholesterol 7 alpha-hydroxylase, the enzyme catalyzing the rate-limiting step of bile acid synthesis, is more sensitive to bile acid suppression. In addition, hepatic bile acid export in humans is more dependent on the bile salt export pump (BSEP). To explore the molecular basis for these species differences, we analyzed the function of the ligand-binding domain (LBD) of human and murine farnesoid X receptor (FXR), a nuclear receptor for bile acids. We observed a strong interspecies difference in bile acid-mediated FXR function; in the coactivator association assay, chenodeoxycholate (CDCA) activated human FXR-LBD with 10-fold higher affinity and 3-fold higher maximum response than murine FXR-LBD. Consistently, in HepG2 cells human FXR-LBD increased reporter expression more robustly in the presence of CDCA. The basis for these differences was investigated by preparing chimeric receptors and by site-directed mutagenesis. Remarkably, the double replacements of Lys(366) and Val(384) in murine FXR (corresponding to Asn(354) and Ile(372) in human FXR) with Asn(366) and Ile(384) explained the difference in both potency and maximum activation; compared with the wild-type murine FXR-LBD, the double mutant gained 8-fold affinity and more than 250% maximum response to CDCA in vitro. This mutant also increased reporter expression to an extent comparable with that of human FXR-LBD in HepG2 cells. These results demonstrate that Asn(354) and Ile(372) are critically important for FXR function and that murine FXR can be "humanized" by substituting with the two corresponding residues of human FXR. Consistent with the difference in FXR-LBD transactivation, CDCA induced endogenous expression of human BSEP by 10-12-fold and murine BSEP by 2-3-fold in primary hepatocytes. This study not only provides the identification of critical residues for FXR function but may also explain the species difference in bile acids/cholesterol metabolism.
Assuntos
Asparagina/fisiologia , Ácido Quenodesoxicólico/farmacologia , Proteínas de Ligação a DNA/efeitos dos fármacos , Isoleucina/fisiologia , Fatores de Transcrição/efeitos dos fármacos , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Linhagem Celular , Proteínas de Ligação a DNA/química , Humanos , Ligantes , Fígado/metabolismo , Camundongos , Mutagênese Sítio-Dirigida , RNA Mensageiro/metabolismo , Receptores Citoplasmáticos e Nucleares , Relação Estrutura-Atividade , Fatores de Transcrição/químicaRESUMO
Somatostatin (SRIH) regulates pituitary adrenocorticotropin (ACTH) secretion by interacting with a family of homologous G protein-coupled membrane receptors. The SRIH receptor subtypes (sst(1)-sst(5)) that control ACTH release remain unknown. Using novel, subtype-selective SRIH analogs, we have identified the SRIH receptor subtypes involved in regulating ACTH release from AtT-20 cells, a model for cell line pituitary corticotropes. Radioligand-binding studies with (125)I-SRIH-14 and (125)I-SRIH-28 showed that SRIH-14 and SRIH-28 recognized specific, high-affinity and saturable membrane-binding sites. Nonpeptidyl agonists with selectivity for the sst(2) (L-779,976; compound 2) or sst(1)/sst(5)) (L-817,818; compound 5) receptor subtypes potently displaced (125)I-SRIH-28 from AtT-20 cell membranes, while agonists selective for the sst(1) (L-779,591; compound 1), sst(3) (L-796,778; compound 3) or sst(4) (L-803,087; compound 4) subtypes were inactive. Tyr(11)-SRIH-14, compound 2 (sst(2)) or compound 5 (sst(5)) inhibited forskolin and corticotropin-releasing hormone (CRH)-induced increases in intracellular cAMP. Furthermore, the sst(2) and sst(5) agonists potently inhibited CRH-induced ACTH release from AtT-20 cells. These results provide the first evidence that sst(2) and sst(5) receptor subtypes, but not sst(1), sst(3) or sst(4), inhibit cAMP accumulation and regulate ACTH secretion in the AtT-20 cell model of the rodent corticotrope.
Assuntos
Hormônio Adrenocorticotrópico/metabolismo , Hormônio Liberador da Corticotropina/farmacologia , Proteínas Fúngicas/fisiologia , Proteínas Ativadoras de GTPase , Hipófise/metabolismo , Receptores de Somatostatina/fisiologia , Proteínas de Saccharomyces cerevisiae , Ligação Competitiva , Linhagem Celular , AMP Cíclico/metabolismo , Proteínas Fúngicas/metabolismo , Radioisótopos do Iodo , Hipófise/efeitos dos fármacos , Ensaio Radioligante , Receptores de Somatostatina/metabolismo , Somatostatina/metabolismo , Somatostatina-28RESUMO
A class of flavanoids exhibiting a high degree of selectivity for ERalpha over ERbeta has been discovered. The most active analogue 6 was found to be 66-fold ERalpha-selective and demonstrated uterine estradiol antagonism.