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1.
Int J Clin Pract ; 69(2): 228-34, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25363271

RESUMO

PURPOSE: Whether patients with inflammatory bowel disease (IBD) exhibit a high risk of developing varicella zoster virus (VZV) infection in Asian populations remains inconclusive. We investigated the causal relationship between two diseases by analysing the Taiwan National Health Insurance Research Database. PATIENTS AND METHODS: Based on a universal insurance claims database, we enrolled 7055 IBD patients and 28,220 age- and sex-matched controls. We calculated the hazard ratios (HRs) and 95% confidence intervals (CIs) of the herpes zoster virus (HZV) in the IBD and comparison cohorts, using the Cox proportional hazards regression model. RESULTS: Patients with IBD exhibited significantly higher risk of the HZV compared with the controls (adjusted HRs, 1.42; 95% CI, 1.27-1.60). Further analysis indicated that male patients (adjusted HRs, 1.61; 95% CI, 1.35-1.92), aged 35-44 (adjusted HRs, 1.47; 95% CI, 1.08-2.01) and aged 65 years and older (adjusted HRs, 1.47; 95% CI, 1.19-1.80), and patients without comorbidities (adjusted HRs, 1.44; 95% CI, 1.26-1.66), exhibited excessive risks of VZV infection. Moreover, our findings show that the overall risk of developing VZV infection increased risk from 1.03 (95% CI, 0.90-1.18) (≤ 2 visits) to 9.76 (95% CI, 7.60-12.5) (> 4 visits), which correlates positively with the frequency of medical visits (trend test p < 0.0001). CONCLUSION: Patients with IBD, particularly men aged 35-44/65 years and over, and patients without comorbidities, are associated with a long-term risk of VZV infection. The excessive risk of VZV infection should be considered for administering vaccines to IBD patients.


Assuntos
Herpesvirus Humano 3 , Doenças Inflamatórias Intestinais/complicações , Adulto , Idoso , Povo Asiático , Varicela/epidemiologia , Estudos de Coortes , Comorbidade , Feminino , Herpes Zoster/epidemiologia , Humanos , Doenças Inflamatórias Intestinais/epidemiologia , Masculino , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais , Fatores de Risco , Taiwan/epidemiologia
2.
Eur J Clin Microbiol Infect Dis ; 33(9): 1653-9, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24715153

RESUMO

Chronic fatigue syndrome (CFS) is a complex disorder accompanied by unexplainable persistent fatigue, in which several etiological factors exist, such as viral infections. Using the National Health Insurance Research Database (NHIRD) of Taiwan, this study evaluated the association between herpes zoster (HZ) infection and the risk of CFS, and examined the possibility of patients developing postviral fatigue effects, including the possibility of developing other unexplainable chronic fatigue conditions. In this prospective cohort study using the NHIRD, we identified 9,205 patients with HZ infection [ICD-9 (International Classification of Disease, Ninth Revision), code 053] and 36,820 patients without HZ infection (non-HZ) from 2005 to 2007, and followed up to the end of 2010. The incidence rate of CFS was higher in the HZ cohort than in the non-HZ cohort (4.56 vs. 3.44 per 1,000 person-years), with an adjusted hazard ratio of 1.29 [95 % confidence interval (CI) = 1.09-1.53]. It was shown that the risk of CFS without comorbidity for each patient increased from 1.25- to 1.36-fold between the CFS and non-CFS cohorts; with long-term follow-up, the HZ cohort showed a significantly higher cumulative incidence rate of developing CFS than the non-HZ patients. We propose that patients with chronic fatigue might exist in a subset of patients that would be associated with HZ infection. The actual mechanism of development of CFS that is attributed to HZ infection remains unclear. The findings of this population cohort study provide pivotal evidence of postviral fatigue among patients with HZ infection.


Assuntos
Síndrome de Fadiga Crônica/epidemiologia , Herpes Zoster/complicações , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Medição de Risco , Taiwan/epidemiologia , Adulto Jovem
3.
Psychol Med ; 41(11): 2287-96, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21524332

RESUMO

BACKGROUND: There is compelling evidence that children of mothers with postnatal depression (PD) experience poor developmental outcomes. However, no studies have specifically ascertained the risk of mortality for offspring during preschool years, the most catastrophic outcome in the vulnerable period. This nationwide population-based study aimed to investigate whether maternal depression in the first year after giving birth was associated with increased mortality risk among their preschool children aged up to 5 years. METHOD: Three nationwide population-based datasets [the National Health Insurance Research Database (NHIRD), birth certificate registry and death certificate registry] were linked in this study. A total of 10 236 offspring of mothers with PD were recruited, together with a comparison cohort of 81 888 births matched with the affected women in terms of maternal age and year of delivery. Each child was traced for 5 years from delivery between 2001 and 2003 until the end of 2008 to determine mortality during preschool years. RESULTS: During preschool years, 98 (0.96%) deaths were identified among the offspring of mothers with PD and 470 (0.57%) children in the comparison cohort died. For children up to 5 years old, exposure to maternal PD was independently associated with a 1.47-fold [95% confidence interval (CI) 1.16-1.87] increased mortality risk, after adjusting for family income, urbanization level and the characteristics of mother, father and infant. The risk of death by unnatural causes was even higher (about 2.23 times the risk, 95% CI 1.34-3.70) among exposed offspring. CONCLUSIONS: PD places preschool children at significantly increased risk of mortality, especially from unnatural causes of death.


Assuntos
Mortalidade da Criança , Filho de Pais com Deficiência/estatística & dados numéricos , Depressão Pós-Parto/epidemiologia , Mortalidade Infantil , Mortalidade Prematura , Acidentes/mortalidade , Adulto , Estudos de Casos e Controles , Causas de Morte , Pré-Escolar , Feminino , Homicídio/estatística & dados numéricos , Humanos , Lactente , Recém-Nascido , Masculino , Modelos de Riscos Proporcionais , Risco , Taiwan/epidemiologia
4.
Dev Neurosci ; 32(4): 313-20, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20938157

RESUMO

The myelin-associated protein Nogo-A is a well-known inhibitor of axonal regeneration and compensatory plasticity, yet functions of neuronal Nogo-A are not as clear. The present study examined the effects of decreased levels of neuronal Nogo-A on dendritic spines of developing neocortical neurons. Decreased Nogo-A levels in these neurons resulted in lowered spine density and an increase in filopodial type protrusions. These results suggest a role for neuronal Nogo-A in maintaining a spine phenotype in neocortical pyramidal cells.


Assuntos
Espinhas Dendríticas/ultraestrutura , Proteínas da Mielina/metabolismo , Neocórtex/patologia , Células Piramidais/ultraestrutura , Animais , Western Blotting , Linhagem Celular , Espinhas Dendríticas/metabolismo , Técnicas de Silenciamento de Genes , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Microscopia Confocal , Proteínas da Mielina/genética , Neocórtex/metabolismo , Proteínas Nogo , Células Piramidais/metabolismo , Interferência de RNA , Ratos
5.
Science ; 204(4390): 314-6, 1979 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-432646

RESUMO

A study was made of the function of the intervening sequences in the ovalbumin gene, Radioactively labeled DNA probes for the intervening sequences were prepared and RNA's were isolated from whole cells, nuclei, and polysomes of estrogen-stimulated chick oviducts. The concentrations of messenger RNA (mRNA) transcripts from ovalbumin structural sequences (mRNAov) and transcripts corresponding to intervening sequences were then estimated by hybridization to cloned DNA probes. Oviduct tissue contains approximately 58,000 molecules of mRNAov sequences per tubular gland cell and most of these sequences are present in the cytoplasm. In contrast, there are 200 to 300 molecules of RNA per cell which are transcribed from the intervening sequences of the natural ovalbumin gene and almost all of these are found in the nucleus. The difference in distribution of structural and intervening sequence transcripts suggests that, unlike mature mRNA, the intervening sequences are not preferentially transported to cytoplasmic polysomes.


Assuntos
Genes , Precursores de Ácido Nucleico/genética , Ovalbumina/genética , RNA Mensageiro/genética , Transcrição Gênica , Animais , Transporte Biológico , Núcleo Celular/metabolismo , Galinhas , Citoplasma/metabolismo , Técnicas In Vitro , Precursores de Ácido Nucleico/metabolismo , Oviductos , Polirribossomos/metabolismo
6.
Science ; 270(5240): 1354-7, 1995 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-7481822

RESUMO

A yeast two-hybrid system was used to identify a protein that interacts with and enhances the human progesterone receptor (hPR) transcriptional activity without altering the basal activity of the promoter. Because the protein stimulated transactivation of all the steroid receptors tested, it has been termed steroid receptor coactivator-1 (SRC-1). Coexpression of SRC-1 reversed the ability of the estrogen receptor to squelch activation by hPR. Also, the amino terminal truncated form of SRC-1 acted as a dominant-negative repressor. Together, these results indicate that SRC-1 encodes a coactivator that is required for full transcriptional activity of the steroid receptor superfamily.


Assuntos
Receptores de Progesterona/metabolismo , Receptores de Esteroides/metabolismo , Transativadores/metabolismo , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Ativação Transcricional , Sequência de Aminoácidos , Sequência de Bases , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Expressão Gênica , Células HeLa , Histona Acetiltransferases , Antagonistas de Hormônios/metabolismo , Antagonistas de Hormônios/farmacologia , Humanos , Mifepristona/metabolismo , Mifepristona/farmacologia , Dados de Sequência Molecular , Coativador 1 de Receptor Nuclear , Promegestona/farmacologia , Proteínas Recombinantes de Fusão/metabolismo , Fatores de Transcrição/genética , Transfecção
7.
Science ; 278(5345): 1947-50, 1997 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-9395397

RESUMO

A Sonic hedgehog (Shh) response element was identified in the chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) promoter that binds to a factor distinct from Gli, a gene known to mediate Shh signaling. Although this binding activity is specifically stimulated by Shh-N (amino-terminal signaling domain), it can also be unmasked with protein phosphatase treatment in the mouse cell line P19, and induction by Shh-N can be blocked by phosphatase inhibitors. Thus, Shh-N signaling may result in dephosphorylation of a target factor that is required for activation of COUP-TFII-, Islet1-, and Gli response element-dependent gene expression. This finding identifies another step in the Shh-N signaling pathway.


Assuntos
Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica , Fosfoproteínas Fosfatases/metabolismo , Proteínas/genética , Proteínas/metabolismo , Receptores de Esteroides , Transativadores , Fatores de Transcrição/genética , Animais , Fator II de Transcrição COUP , Fatores de Transcrição COUP , Linhagem Celular , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Inibidores Enzimáticos/farmacologia , Proteínas Hedgehog , Toxinas Marinhas , Camundongos , Ácido Okadáico/farmacologia , Oxazóis/farmacologia , Fosfoproteínas Fosfatases/antagonistas & inibidores , Fosforilação , Regiões Promotoras Genéticas , Transdução de Sinais , Fatores de Transcrição/metabolismo
8.
Science ; 279(5358): 1922-5, 1998 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-9506940

RESUMO

The in vivo biological function of a steroid receptor coactivator was assessed in mice in which the SRC-1 gene was inactivated by gene targeting. Although in both sexes the homozygous mutants were viable and fertile, target organs such as uterus, prostate, testis, and mammary gland exhibited decreased growth and development in response to steroid hormones. Expression of RNA encoding TIF2, a member of the SRC-1 family, was increased in the SRC-1 null mutant, perhaps compensating partially for the loss of SRC-1 function in target tissues. The results indicate that SRC-1 mediates steroid hormone responses in vivo and that loss of its coactivator function results in partial resistance to hormone.


Assuntos
Genitália Masculina/crescimento & desenvolvimento , Hormônios Esteroides Gonadais/farmacologia , Glândulas Mamárias Animais/crescimento & desenvolvimento , Fatores de Transcrição/fisiologia , Útero/crescimento & desenvolvimento , Animais , Linhagem Celular , Resistência a Medicamentos , Estradiol/sangue , Estradiol/farmacologia , Feminino , Marcação de Genes , Genitália Masculina/efeitos dos fármacos , Histona Acetiltransferases , Masculino , Glândulas Mamárias Animais/efeitos dos fármacos , Camundongos , Coativador 1 de Receptor Nuclear , Coativador 2 de Receptor Nuclear , Tamanho do Órgão/efeitos dos fármacos , Gravidez , Progesterona/sangue , Progesterona/farmacologia , Próstata/efeitos dos fármacos , Próstata/crescimento & desenvolvimento , Células-Tronco , Testículo/efeitos dos fármacos , Testículo/crescimento & desenvolvimento , Testosterona/sangue , Testosterona/farmacologia , Fatores de Transcrição/genética , Útero/efeitos dos fármacos
9.
Neurobiol Stress ; 10: 100145, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30937351

RESUMO

Prenatal substance exposure is a growing public health concern worldwide. Although the opioid crisis remains one of the most prevalent addiction problems in our society, abuse of cocaine, methamphetamines, and other illicit drugs, particularly amongst pregnant women, are nonetheless significant and widespread. Evidence demonstrates prenatal drug exposure can affect fetal brain development and thus can have long-lasting impact on neurobehavioral and cognitive performance later in life. In this review, we highlight research examining the most prevalent drugs of abuse and their effects on brain development with a focus on endoplasmic reticulum stress and oxidative stress signaling pathways. A thorough exploration of drug-induced cellular stress mechanisms during prenatal brain development may provide insight into therapeutic interventions to combat effects of prenatal drug exposure.

10.
Neuron ; 24(4): 847-59, 1999 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-10624948

RESUMO

Chicken ovalbumin upstream promotor-transcription factor I (COUP-TFI), an orphan member of the nuclear receptor superfamily, is highly expressed in the developing nervous systems. In the cerebral cortex of Coup-tfl mutants, cortical layer IV was absent due to excessive cell death, a consequence of the failure of thalamocortical projections. Moreover, subplate neurons underwent improper differentiation and premature cell death during corticogenesis. Our results indicate that the subplate neuron defects lead to the failure of guidance and innervation of thalamocortical projections. Thus, our findings demonstrate a critical role of the subplate in early corticothalamic connectivity and confirm the importance of afferent innervation for the survival of layer IV neurons. These results also substantiate COUP-TFI as an important regulator of neuronal development and differentiation.


Assuntos
Córtex Cerebral/fisiologia , Proteínas de Ligação a DNA/fisiologia , Neurônios/fisiologia , Receptores de Glucocorticoides/fisiologia , Tálamo/fisiologia , Fatores de Transcrição/fisiologia , Animais , Antimetabólitos , Axônios/fisiologia , Bromodesoxiuridina , Fator I de Transcrição COUP , Carbocianinas , Morte Celular/fisiologia , Diferenciação Celular/fisiologia , Córtex Cerebral/citologia , Córtex Cerebral/crescimento & desenvolvimento , Corantes Fluorescentes , Imuno-Histoquímica , Hibridização In Situ , Masculino , Camundongos , Mutação/genética , Vias Neurais/crescimento & desenvolvimento , Tálamo/citologia , Tálamo/crescimento & desenvolvimento
11.
Food Chem Toxicol ; 46(8): 2764-9, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18550245

RESUMO

Geniposide, an iridoid glucoside, is a major constituent in the fruits of Gardenia jasminoides (Gardenia fruits), a popular Chinese herb. Genipin, the aglycone of geniposide, is used to prepare blue colorants in food industry and also a crosslinking reagent for biological tissue fixation. In this study, we investigated the metabolism and pharmacokinetics of genipin and geniposide in rats. Blood samples were withdrawn via cardiopuncture and the plasma samples were assayed by HPLC method before and after hydrolysis with sulfatase and beta-glucuronidase. The results indicated that after oral administration of genipin or Gardenia fruit decoction, genipin sulfate was a major metabolite in the bloodstream, whereas the parent forms of genipin and geniposide were not detected. Importantly, oral administration of 200mg/kg of genipin resulted in a mortality of 78% (7/9) in rats.


Assuntos
Colagogos e Coleréticos/metabolismo , Colagogos e Coleréticos/farmacocinética , Iridoides/metabolismo , Iridoides/farmacocinética , Animais , Calibragem , Fenômenos Químicos , Físico-Química , Colagogos e Coleréticos/toxicidade , Cromatografia Líquida de Alta Pressão , Interpretação Estatística de Dados , Gardenia/química , Hidrólise , Injeções Intravenosas , Glicosídeos Iridoides , Iridoides/toxicidade , Masculino , Extratos Vegetais/química , Extratos Vegetais/farmacocinética , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes
12.
Mol Cell Biol ; 19(4): 2734-45, 1999 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10082539

RESUMO

The formation of various tissues requires close communication between two groups of cells, epithelial and mesenchymal cells. COUP-TFs are transcription factors which have been shown to have functions in embryonic development. COUP-TFI is expressed mainly in the nervous system, and its targeted deletion leads to defects in the central and peripheral nervous systems. COUP-TFII is highly expressed in the mesenchymal component of the developing organs. A null mutation of COUP-TFII results in the malformation of the heart and blood vessels. From their expression pattern, we proposed that COUP-TFs regulate paracrine signals important for mesenchymal cell-epithelial cell interactions. In order to identify genes regulated by COUP-TF in this process, a rat urogenital mesenchymal cell line was stably transfected with a COUP-TFI expression vector. We found that NGFI-A, a gene with important functions in brain, organ, and vasculature development, has elevated mRNA and protein levels upon overexpression of COUP-TFI in these cells. A study of the promoter region of this gene identified a COUP-TF-responsive element between positions -64 and -46. Surprisingly, this region includes binding sites for members of the Sp1 family of transcription factors but no COUP-TF binding site. Mutations that abolish the Sp1 binding activity also impair the transactivation of the NGFI-A promoter by COUP-TF. Two regions of the COUP-TF molecule are shown to be important for NGFI-A activation: the DNA binding domain and the extreme C terminus of the putative ligand binding domain. The C-terminal region is likely to be important for interaction with coactivators. In fact, the coactivators p300 and steroid receptor activator 1 can enhance the transactivation of the NGFI-A promoter induced by COUP-TFI. Finally, we demonstrated that COUP-TF can directly interact with Sp1. Taken together, these results suggest that NGFI-A is a target gene for COUP-TFs and that the Sp1 family of transcription factors mediates its regulation by COUP-TFs.


Assuntos
Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas Imediatamente Precoces , Próstata/crescimento & desenvolvimento , Fator de Transcrição Sp1/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Animais , Sítios de Ligação , Fator I de Transcrição COUP , Proteínas de Ligação a DNA/biossíntese , Proteína 1 de Resposta de Crescimento Precoce , Células Epiteliais/citologia , Regulação da Expressão Gênica no Desenvolvimento , Histona Acetiltransferases , Masculino , Mesoderma/citologia , Modelos Genéticos , Coativador 1 de Receptor Nuclear , Coativador 3 de Receptor Nuclear , Comunicação Parácrina , Ligação Proteica , Ratos , Proteínas Recombinantes/metabolismo , Elementos de Resposta , Transativadores/metabolismo , Fatores de Transcrição/biossíntese , Ativação Transcricional , Regulação para Cima , Sistema Urogenital/citologia
13.
Mol Cell Biol ; 12(9): 4153-63, 1992 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-1324415

RESUMO

Alignment of natural chicken ovalbumin upstream promoter transcription factor (COUP-TF) response elements shows that, in addition to the predominant direct repeat of the GGTCA motif with a 2-bp spacing, there are other functional COUP elements with variations in the GGTCA orientation and spacing. We systematically analyzed the binding of in vitro-synthesized COUP-TFs and showed that COUP-TF is capable of binding to oligonucleotides containing both direct repeats and palindromes and with different spacings of the GGTCA repeats. Subsequently, we analyzed four possible mechanisms proposed to explain how COUP-TF could bind to these spatial variations of the GGTCA repeat. We demonstrated that the functional DNA-binding form of COUP-TF is a dimer which requires two GGTCA half-sites to bind DNA. We demonstrated that the COUP-TF dimer undergoes a remarkable structural adaptation to accommodate binding to these spatial variants of the GGTCA repeats. A functional consequence of the promiscuous DNA binding of COUP-TF is its ability to down-regulate hormonal induction of target gene expression by other members of the steroid-thyroid hormone receptor superfamily such as the vitamin D3, thyroid hormone, and retinoic acid receptors. Our data indicate that COUP-TF may have an important role in hormonal regulation of gene expression by these receptors.


Assuntos
Proteínas de Transporte/fisiologia , Colecalciferol/fisiologia , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica/fisiologia , Hormônios Tireóideos/fisiologia , Fatores de Transcrição/metabolismo , Tretinoína , Animais , Sequência de Bases , Fator I de Transcrição COUP , Linhagem Celular , DNA/metabolismo , Proteínas de Ligação a DNA/química , Regulação para Baixo , Dados de Sequência Molecular , Receptores do Ácido Retinoico , Sequências Repetitivas de Ácido Nucleico , Soluções , Fatores de Transcrição/química
14.
Mol Cell Biol ; 21(23): 8056-67, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11689696

RESUMO

We have previously demonstrated that overexpression of Cdc25B in transgenic mice resulted in mammary gland hyperplasia and increased steroid hormone responsiveness. To address how Cdc25B enhances the hormone responsiveness in mammary glands, we showed that Cdc25B stimulates steroid receptor-dependent transcription in transient transfection assays and in a cell-free assay with chromatin templates. Surprisingly, the effect of Cdc25B on steroid receptors is independent of its protein phosphatase activity in vitro. The direct interactions of Cdc25B with steroid receptors, on the other hand, were evidenced in in vivo and in vitro assays, suggesting the potential direct contribution of Cdc25B on the steroid receptor-mediated transcription. In addition, p300/CBP-associated factor and CREB binding protein were shown to interact and synergize with Cdc25B and further enhance its coactivation activity. Thus, we have uncovered a novel function of Cdc25B that serves as a steroid receptor coactivator in addition to its role as a regulator for cell cycle progression. This dual function might likely contribute to its oncogenic action in breast cancer.


Assuntos
Mama/metabolismo , Proteínas de Ciclo Celular/metabolismo , Receptores de Esteroides/metabolismo , Proteínas de Saccharomyces cerevisiae , Fosfatases cdc25/metabolismo , Acetiltransferases/metabolismo , Animais , Proteína de Ligação a CREB , Ciclo Celular/fisiologia , Proteínas de Ciclo Celular/farmacologia , Linhagem Celular , Sistema Livre de Células/metabolismo , Ciclina D1/metabolismo , Ativação Enzimática/fisiologia , Feminino , Regulação da Expressão Gênica/fisiologia , Histona Acetiltransferases , Humanos , Proteínas Nucleares/metabolismo , Ratos , Receptores Androgênicos/metabolismo , Receptores de Estrogênio/metabolismo , Receptores de Glucocorticoides/metabolismo , Receptores de Progesterona/metabolismo , Transativadores/metabolismo , Fatores de Transcrição , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/fisiologia , Fosfatases cdc25/farmacologia , Fatores de Transcrição de p300-CBP
15.
Mol Cell Biol ; 11(10): 4998-5004, 1991 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1922029

RESUMO

Steroid receptors regulate transcription of target genes in vivo and in vitro in a steroid hormone-dependent manner. Unoccupied progesterone receptor exists in the low-salt homogenates of target cells as a functionally inactive 8 to 10S complex with several nonreceptor components such as two molecules of 90-kDa heat shock protein (hsp90), a 70-kDa heat shock protein (hsp70), and a 56-kDa heat shock protein (hsp56). Ligand-induced dissociation of receptor-associated proteins such as hsp90 has been proposed as the mechanism of receptor activation. Nevertheless, it has not been established whether, beyond release of heat shock proteins, the steroidal ligand plays a role in modulating receptor activity. To examine whether the release of these nonreceptor proteins from receptor complex results in a constitutively active receptor, we isolated an unliganded receptor form essentially free of hsp90, hsp70, and hsp56. Using a recently developed steroid hormone-responsive cell-free transcription system, we demonstrate for the first time that the dissociation of heat shock proteins is not sufficient to generate a functionally active receptor. This purified receptor still requires hormone for high-affinity binding to a progesterone response element and for efficient transcriptional activation of a target gene. When an antiprogestin, Ru486, is bound to the receptor, it fails to promote efficient transcription. We propose that in the cell, in addition to the release of receptor-associated inhibitory proteins, a distinct hormone-mediated activation event must precede efficient gene activation.


Assuntos
Proteínas de Choque Térmico/metabolismo , Progesterona/farmacologia , Receptores de Progesterona/fisiologia , Transcrição Gênica/efeitos dos fármacos , Western Blotting , Sistema Livre de Células , Células HeLa , Humanos , Mifepristona/farmacologia , Testes de Precipitina , Receptores de Progesterona/química , Receptores de Progesterona/efeitos dos fármacos , Receptores de Progesterona/isolamento & purificação , Células Tumorais Cultivadas
16.
Mol Cell Biol ; 8(10): 4362-9, 1988 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3263567

RESUMO

The human alpha-1-antitrypsin (AAT) gene is expressed in the liver, and its deficiency causes pulmonary emphysema. We have demonstrated that its 5'-flanking region contains cis-acting elements capable of directing proper transcription in the presence of rat liver nuclear extract. The in vitro transcription system is tissue-specific in that the AAT promoter is functional in nuclear extracts prepared from the liver but not from HeLa cells. Experiments in which rat liver and HeLa nuclear extracts were mixed suggested the presence of a specific activator(s) in hepatocytes rather than a repressor(s) in nonproducing cells. Two protected regions were detected in the promoter by DNase I footprinting analysis with rat liver nuclear extracts. Region one spanned -78 to -52 and region two spanned -125 to -100 in the 5'-flanking sequence of the gene. By gel retardation assays with synthetic oligonucleotides, at least two distinct liver nuclear factors were identified, HNF-1 and HNF-2 (hepatocyte nuclear factors), which bound specifically to the first and second region, respectively. We present evidence that HNF-1 and HNF-2 are positively acting, tissue-specific transcription factors that regulate hepatic expression of the human AAT gene.


Assuntos
Fígado/fisiologia , Proteínas Nucleares/fisiologia , Regiões Promotoras Genéticas , Fatores de Transcrição/fisiologia , alfa 1-Antitripsina/genética , Animais , Sequência de Bases , Ligação Competitiva , Sistema Livre de Células , Regulação da Expressão Gênica , Oligodesoxirribonucleotídeos/metabolismo , Ratos , Transcrição Gênica
17.
Mol Cell Biol ; 16(5): 2332-40, 1996 May.
Artigo em Inglês | MEDLINE | ID: mdl-8628300

RESUMO

COUP-TF, an orphan member of the nuclear receptor superfamily, has been proposed to play a key role in regulating organogenesis, neurogenesis, and cellular differentiation during embryonic development. Since heterodimierization is a common theme within the nuclear receptor superfamily and has been demonstrated to modulate transcriptional properties of heterodimeric partners via allosteric interactions, we have devised a strategy to examine the silencing function of COUP-TF in a heterodimeric context. We find that the intrinsic active repression function of COUP-TF is not affected by heterodimerization. Moreover, COUP-TF can transrepress the ligand-dependent activation of its heterodimeric partners without its own DNA binding site. Using receptor deletion mutants in transfection assays, we show that the region necessary for COUP-TF silencing function is not sufficient for its transrepression activity. Furthermore, our studies indicate that in addition to its active repression function, COUP-TF can repress several different types of activator-dependent transactivation. However, this active repression function of COUP-TF may be differentially regulated by some other activator(s). These studies provide new insights into the molecular mechanism(s) of COUP-TF-mediated repression.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , Fatores de Transcrição/metabolismo , Transcrição Gênica , Regulação Alostérica , Animais , Sequência de Bases , Fator I de Transcrição COUP , Cloranfenicol O-Acetiltransferase/biossíntese , Proteínas de Ligação a DNA/biossíntese , Humanos , Cinética , Células L , Substâncias Macromoleculares , Camundongos , Dados de Sequência Molecular , Mutagênese , Oligodesoxirribonucleotídeos , Receptores de Glucocorticoides/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/metabolismo , Deleção de Sequência , Supressão Genética , Fatores de Transcrição/biossíntese , Transfecção
18.
Mol Cell Biol ; 7(12): 4151-8, 1987 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-3437886

RESUMO

Previous studies established that the chicken ovalbumin gene upstream promoter (COUP) sequence, which lies between -70 and -90 base pairs upstream from the cap site, is essential for the efficient transcription of the ovalbumin gene. A transcription factor which binds to this sequence has been purified from the homologous chicken oviduct cells. The purification scheme starting from oviduct nuclear extract involved a combination of conventional column and sequence-specific DNA affinity chromatography steps. Using gel retardation and DNase I footprinting techniques to assay COUP-binding activity, we achieved extensive purification of this factor. Binding competition studies with the purified factor indicated that it bound specifically to the COUP sequence and that the binding could be competed for only by the promoter DNA fragments or synthetic oligonucleotides containing the COUP sequence. The purified protein preparation showed multiple polypeptide bands on polyacrylamide gel electrophoresis. Renaturation of separated polypeptides after extraction from the gel matrix was carried out. The majority of renatured polypeptides exhibited specific binding to the COUP sequence.


Assuntos
Ovalbumina/genética , Oviductos/análise , Fatores de Transcrição/isolamento & purificação , Animais , Ligação Competitiva , Núcleo Celular/análise , Galinhas , Cromatografia , Cromatografia de Afinidade , DNA/metabolismo , Desoxirribonuclease I , Eletroforese em Gel de Poliacrilamida , Feminino , Peso Molecular , Regiões Promotoras Genéticas , Desnaturação Proteica , Fatores de Transcrição/metabolismo , Transcrição Gênica
19.
Mol Cell Biol ; 8(5): 2070-7, 1988 May.
Artigo em Inglês | MEDLINE | ID: mdl-3290646

RESUMO

Band-shifting and DNase I-footprinting assays have been used to study the trans-acting factor(s) binding to an important promoter element (-53 to -46 relative to the transcription start) of the rat insulin II gene. A binding activity which footprints a region between -60 and -40 was found in both HIT, a hamster insulinoma cell line, and HeLa cells. A mutation within this region which drastically decreases promoter activity in vivo also greatly reduces binding activity in vitro. This binding activity was purified from HeLa cells and identified by competition and renaturation analyses as being the same as the COUP (chicken ovalbumin upstream promoter) transcription factor, a DNA-binding protein required for efficient transcription of the ovalbumin gene in vitro. Interestingly, the binding sequences of the COUP transcription factor in the ovalbumin and the insulin promoters have only limited similarities.


Assuntos
Insulina/genética , Regiões Promotoras Genéticas , Fatores de Transcrição/metabolismo , Animais , Galinhas , Células HeLa/metabolismo , Humanos , Ovalbumina/genética , Ratos
20.
Mol Cell Biol ; 15(1): 255-63, 1995 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7799932

RESUMO

Steroid, thyroid, and retinoid hormones exert their biological functions by interacting with their cognate nuclear receptors. Upon binding receptors, hormones induce a protease-resistant structural change in the receptor ligand-binding domain and subsequently activate the receptors. Utilizing partial proteolysis, we have been able to delineate a region in the mouse retinoid X receptor beta (mRXR beta) required for ligand binding. A separable activation domain within the mRXR beta E region has been identified. The activation domain, which is 21 amino acids in length, is located at the extreme C terminus of mRXR beta. This domain is not required for ligand binding since removal of this sequence neither eliminates the ligand-induced, protease-resistant conformational change nor alters the ligand-enhanced DNA binding. Furthermore, deletion of this activation domain converts the receptor into a transcriptional silencer. Finally, a further truncation of 9 amino acids (for a total of 30 amino acids) from the C terminus results in a mutant which does not undergo the protease-resistant conformational change and cannot bind DNA as a homodimer. Nevertheless, this mutant is still able to form a heterodimer with the thyroid hormone receptor. Therefore, homodimerization and heterodimerization can be distinguished by this nine-amino-acid sequence.


Assuntos
Receptores do Ácido Retinoico/química , Proteínas Repressoras/química , Transativadores/química , Fatores de Transcrição/química , Sequência de Aminoácidos , Animais , Sequência de Bases , Endopeptidases/metabolismo , Técnicas In Vitro , Camundongos , Dados de Sequência Molecular , Estrutura Secundária de Proteína , Receptores do Ácido Retinoico/metabolismo , Receptores X de Retinoides , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Relação Estrutura-Atividade , Fatores de Transcrição/metabolismo , Ativação Transcricional , Tretinoína/metabolismo
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