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1.
Int J Psychiatry Med ; 52(1): 3-20, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28486881

RESUMO

Objectives Home telemental health services have the potential to overcome many individual and systemic barriers to care facing military veterans with posttraumatic stress disorder. However, little is known about the home telemental health-related attitudes and experiences of highly underserved rural or ethnically, racially diverse veterans. This study evaluated whether ethnically/racially diverse U.S. veterans residing in the rural Pacific Islands would find the delivery of evidence-based treatment for posttraumatic stress disorder via home telemental health tablet devices useful and helpful. Method Clinicians located in a central urban location delivered Cognitive Processing Therapy for posttraumatic stress disorder directly into patients' homes via a tablet device and secure WiFi connection. Pre- and post-treatment measures were collected from a clinical sample of 47 veterans (average age: 49.3 years). Most (74.4%) self-identified as being of ethnic/racial minority background. Attitudinal, satisfaction, and usability scales were collected from home telemental health engaging ( n = 29) and non-engaging ( n = 18) veterans. Results Ratings on measures of home telemental health comfort, satisfaction with care, and usability were uniformly positive. Veterans were equally open to receiving mental health services at home via home telemental health or in the clinic. In the case of services for a physical problem, however, veterans preferred in-clinic care. Following treatment, veterans' attitudinal scores increased on items such as "There is enough therapist contact in home telemental health interventions." However, a small portion of veterans (7%) reported having technical or privacy concerns. Conclusion The provision of evidence-based posttraumatic stress disorder treatment directly into the patients' homes proved feasible and was well received by the large majority of rural ethnically/racially diverse veterans.


Assuntos
Terapia Cognitivo-Comportamental/métodos , Internet , Serviços de Saúde Mental , Satisfação do Paciente , Transtornos de Estresse Pós-Traumáticos/terapia , Telemedicina/métodos , Veteranos , Adulto , Computadores de Mão , Humanos , Masculino , Pessoa de Meia-Idade , Polinésia , População Rural , Estados Unidos
2.
Opt Express ; 15(19): 12197-205, 2007 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-19547587

RESUMO

The total process cycle time for large ULE((R)) and Zerodur((R))optics can be improved using a precise and rapid grinding process, with low levels of surface waviness and subsurface damage. In this paper, the amounts of defects beneath ULE((R)) and Zerodur((R) )surfaces ground using a selected grinding mode were compared. The grinding response was characterised by measuring: surface roughness, surface profile and subsurface damage. The observed subsurface damage can be separated into two distinct depth zones, which are: 'process' and 'machine dynamics' related.

3.
Bone ; 38(3): 444-9, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16361121

RESUMO

The effect of bisphosphonates on trabecular microarchitecture may contribute to the reduced risk of vertebral fracture with treatment independent of the bone volume. Trabecular structure was examined at the twelfth thoracic vertebra after 2 years of treatment of two groups of ovariectomized baboons on high and low doses of alendronate, compared with ovariectomized and non-ovariectomized controls. Standard 2D histological measurements showed that alendronate treatment of ovariectomized animals resulted in significantly higher total trabecular length and a lower marrow star volume in comparison with ovariectomized controls indicating preservation of connectivity. Similarly when the vertebrae were examined using a novel thick slice technique that combines 2D and 3D information, ovariectomy produced a significantly higher number of "real" trabecular termini in comparison with normal. When ovariectomized animals were treated with increasing doses of alendronate, fewer "real" termini were seen. MicroCT analysis (2D and 3D) correlated well with the histological measurements, although more variability and less discrimination between groups was seen, with no statistically significant differences with alendronate treatment. Reduced vertebral fracture risk with alendronate may be due to a combination of factors including the increased bone volume, reduced turnover and greater mineralization reported by others. Added to this is now suggested the preservation of several aspects of vertebral cancellous architecture, with microscopy the most sensitive method of analysis.


Assuntos
Alendronato/administração & dosagem , Conservadores da Densidade Óssea/administração & dosagem , Técnicas Histológicas/métodos , Vértebras Torácicas/metabolismo , Tomografia Computadorizada por Raios X/métodos , Alendronato/farmacologia , Animais , Densidade Óssea/efeitos dos fármacos , Conservadores da Densidade Óssea/farmacologia , Relação Dose-Resposta a Droga , Feminino , Seguimentos , Histocitoquímica , Ovariectomia , Papio , Vértebras Torácicas/diagnóstico por imagem , Vértebras Torácicas/efeitos dos fármacos , Vértebras Torácicas/patologia , Fatores de Tempo , Resultado do Tratamento
4.
Mamm Genome ; 12(2): 163-8, 2001 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11210187

RESUMO

Bim is a proapoptotic protein of the Bcl-2 family that shares only the short BH3 domain with other members. It has three isoforms, apparently produced by alternative splicing. The demonstration that Bim is essential for certain apoptotic responses and to prevent overproduction of hematopoietic cells suggests that it may be a tumor suppressor. We have, therefore, investigated the organization of the mouse Bim gene, delineating its promoter and splicing, and positioned the gene on both mouse and human chromosomes. Bim has six exons, but the third is a facultative intron that is spliced out in the mRNAs for the smaller isoforms (BimL and BimS), but not that encoding the largest isoform (BimEL). The 0.8-kb region 5' to exon 1, which contains a TATA-less promoter and binding sites for several transcription factors, can drive expression of a reporter gene. Mouse Bim localizes to the distal third of Chromosome (Chr) 2, near the F-G boundary, and its human counterpart to Chr 2q12 or q13. Deletions of these bands have been reported in ten tumors (eight hematopoietic), reinforcing the possibility that Bim is a tumor suppressor. These findings should help to clarify the regulation of Bim expression and to assess whether mutations involving Bim contribute to neoplastic and other diseases.


Assuntos
Processamento Alternativo , Proteínas de Transporte/genética , Cromossomos Humanos Par 2/genética , Proteínas de Membrana , Mapeamento Físico do Cromossomo , Proteínas Proto-Oncogênicas , Animais , Apoptose , Proteínas Reguladoras de Apoptose , Sequência de Bases , Proteína 11 Semelhante a Bcl-2 , Northern Blotting , Éxons , Humanos , Hibridização in Situ Fluorescente , Íntrons , Masculino , Camundongos , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Isoformas de Proteínas/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa
5.
Biotech Histochem ; 75(4): 183-92, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-10999569

RESUMO

Osteoporotic fractures occur frequently in aging populations. Established methods for analyzing microarchitecture indicate that cancellous bone loss in the elderly is associated with progressive reduction in the connectivity of the trabecular network. This disconnection may explain the increased skeletal fragility that is sometimes out of proportion to the amount of bone lost. Connectivity, however, is difficult to measure and usually requires indirect methods. We describe development of a simple, inexpensive and direct procedure for counting sites of trabecular disconnection. The method is based upon preparation of 300-500 microm thick slices of methylmethacrylate embedded material rather than the more usual thin 8 microm histological sections. The marrow tissue is retained within the thick slice; this is essential for conservation of any detached bone fragments. In such preparations differential superficial staining of the upper and lower surfaces with alizarin red and light green, respectively, allows the two-dimensional image to be viewed at the same time as its three-dimensional counterpart. In this way, "real" (i. e., unstained) trabecular termini can be distinguished from "apparent" (i. e., stained red or green) termini that are artifacts of the plane of section. Partly polarized light enhances the microscope image. The method does not destroy the material for subsequent bone histomorphometry and, therefore, may be a useful adjunct to iliac bone biopsy analysis in studies of metabolic bone disease.


Assuntos
Técnicas Histológicas , Ílio/patologia , Osteoporose/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
6.
Bone ; 27(2): 277-82, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10913922

RESUMO

We recently developed a simple and inexpensive method that complements established bone histomorphometry procedures by enabling the two-dimensional imaging of cancellous bone to be viewed within its three-dimensional context with the marrow tissue in place and without detriment to the material for other histological purposes. The method, based on the preparation and superficial staining of slices 300 microm thick, enables "real" (i.e., unstained) trabecular termini to be separated from "artifactual" (i.e., stained) termini, providing a direct measure of cancellous connectivity in osteopenic bone. The technique was applied to osteopenic age-matched, white, postmenopausal women (31 with and 22 without vertebral compression fractures) with a similar bone status, as measured at the spine by absorptiometry and at the iliac crest by histology (see part I of this study). Despite the similarity in the mass of trabecular bone at either site, the results showed a significant difference (p < 0. 05) in the number of "real" trabecular termini between the groups, such that the fracture group had almost four times as many termini (mean +/- SE: 1.98 +/- 0.51/30 mm(2)) at the iliac crest as the nonfracture group (mean +/- SE: 0.53 +/- 0.31/30 mm(2)). Previous histomorphometry of the same material failed to detect a structural distinction between the two groups using established variables. It was concluded that a mass-independent trabecular discontinuity contributes to skeletal failure and that determination of the number of "real" disconnections (i.e., unstained termini) by the direct method proposed may provide a more sensitive discriminant of fracture than the present indirect procedures. A group of fracture and nonfracture men (see part I) suggested a similar distinction (fracture: 0.69 +/- 0.30/30 mm(2); nonfracture: 0.18 +/- 0.18/30 mm(2)), although the difference was not significant.


Assuntos
Ílio/patologia , Vértebras Lombares/lesões , Vértebras Lombares/patologia , Fraturas da Coluna Vertebral/patologia , Idoso , Antraquinonas , Biópsia , Feminino , Humanos , Ílio/ultraestrutura , Processamento de Imagem Assistida por Computador , Vértebras Lombares/ultraestrutura , Masculino , Pessoa de Meia-Idade , Osteoporose Pós-Menopausa/patologia , Valor Preditivo dos Testes , Corantes de Rosanilina , Coloração e Rotulagem
7.
EMBO J ; 18(20): 5666-74, 1999 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-10523309

RESUMO

Protein phosphorylation represents one of the major mechanisms for transcription factor activation. Here we demonstrate a molecular mechanism by which phosphorylation by mitogen-activated protein (MAP) kinases leads to changes in transcription factor activity. MAP kinases stimulate DNA binding and transcriptional activation mediated by the mammalian ETS-domain transcription factor Elk-1. Phosphorylation of the C-terminal transcriptional activation domain induces a conformational change in Elk-1, which accompanies the stimulation of DNA binding. C-terminal phosphorylation is coupled to activation of DNA binding by the N-terminal DNA-binding domain via an additional intermediary domain. Activation of DNA binding is mediated by an allosteric mechanism involving the key phosphoacceptor residues. Together, these results provide a molecular model for how phosphorylation induces changes in Elk-1 activity.


Assuntos
Proteínas de Ligação a DNA , Proteínas Proto-Oncogênicas/metabolismo , Fatores de Transcrição/metabolismo , Regulação Alostérica , Sequência de Aminoácidos , Animais , DNA/metabolismo , Técnicas In Vitro , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Fosforilação , Conformação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas/genética , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Fatores de Transcrição/química , Fatores de Transcrição/genética , Proteínas Elk-1 do Domínio ets
8.
Health Serv J ; 108(5585): 30-1, 1998 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-10176293

RESUMO

Setting up a discharge lounge has proved popular with patients. Referrals from wards have increased but are still spasmodic. When under pressure some staff say they are too busy to transfer patients to the discharge lounge. The ambulance transport service has benefited from being able to pick up most patients awaiting discharge from a single area.


Assuntos
Hospitais Públicos/organização & administração , Alta do Paciente/tendências , Quartos de Pacientes , Ambulâncias , Eficiência Organizacional , Humanos , Tempo de Internação , Serviço de Acompanhamento de Pacientes , Satisfação do Paciente , Medicina Estatal , Reino Unido
9.
Mol Cell Biol ; 17(5): 2876-87, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9111360

RESUMO

The serum response factor (SRF) and myocyte enhancer factor 2A (MEF2A) represent two human members of the MADS-box transcription factor family. Each protein has a distinct biological function which is reflected by the distinct specificities of the proteins for coregulatory protein partners and DNA-binding sites. In this study, we have investigated the mechanism of DNA binding utilized by these two related transcription factors. Although SRF and MEF2A belong to the same family and contain related DNA-binding domains, their DNA-binding mechanisms differ in several key aspects. In contrast to the dramatic DNA bending induced by SRF, MEF2A induces minimal DNA distortion. A combination of loss- and gain-of-function mutagenesis identified a single amino acid residue located at the N terminus of the recognition helices as the critical mediator of this differential DNA bending. This residue is also involved in determining DNA-binding specificity, thus indicating a link between DNA bending and DNA-binding specificity determination. Furthermore, different basic residues within the putative recognition alpha-helices are critical for DNA binding, and the role of the C-terminal extensions to the MADS box in dimerization between SRF and MEF2A also differs. These important differences in the molecular interactions of SRF and MEF2A are likely to contribute to their differing roles in the regulation of specific gene transcription.


Assuntos
Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Proteínas Nucleares/metabolismo , Conformação de Ácido Nucleico , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Humanos , Proteínas de Domínio MADS , Fatores de Transcrição MEF2 , Modelos Moleculares , Dados de Sequência Molecular , Fatores de Regulação Miogênica , Mapeamento de Peptídeos , Conformação Proteica , Fator de Resposta Sérica , Relação Estrutura-Atividade
11.
Mol Cell Biol ; 16(7): 3338-49, 1996 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8668149

RESUMO

Several mechanisms are employed by members of transcription factor families to achieve sequence-specific DNA recognition. In this study, we have investigated how members of the ETS-domain transcription factor family achieve such specificity. We have used the ternary complex factor (TCF) subfamily as an example. ERK2 mitogen-activated protein kinase stimulates serum response factor-dependent and autonomous DNA binding by the TCFs Elk-1 and SAP-la. Phosphorylated Elk-1 and SAP-la exhibit specificities of DNA binding similar to those of their isolated ETS domains. The ETS domains of Elk-1 and SAP-la and SAP-2 exhibit related but distinct DNA-binding specificities. A single residue, D-69 (Elk-1) or V-68 (SAP-1), has been identified as the critical determinant for the differential binding specificities of Elk-1 and SAP-1a, and an additional residue, D-38 (Elk-1) or Q-37 (SAP-1), further modulates their DNA binding. Creation of mutations D38Q and D69V is sufficient to confer SAP-la DNA-binding specificity upon Elk-1 and thereby allow it to bind to a greater spectrum of sites. Molecular modelling indicates that these two residues (D-38 and D-69) are located away from the DNA-binding interface of Elk-1. Our data suggest a mechanism in which these residues modulate DNA binding by influencing the interaction of other residues with DNA.


Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , DNA/química , DNA/metabolismo , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Sítios de Ligação , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Clonagem Molecular , Sequência Consenso , Escherichia coli , Proteína Quinase 1 Ativada por Mitógeno , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos , Plasmídeos , Reação em Cadeia da Polimerase , Estrutura Secundária de Proteína , Proteínas Tirosina Quinases/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Mapeamento por Restrição , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Proteínas Elk-1 do Domínio ets , Proteínas Elk-4 do Domínio ets
12.
Nucleic Acids Res ; 23(22): 4698-706, 1995 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-8524663

RESUMO

The ETS DNA-binding domain is conserved amongst many eukaryotic transcription factors. ETS-domains bind differentially to specific DNA sites containing a central GGA trinucleotide motif. The nucleotides flanking this motif define the binding specificity of individual proteins. In this study we have investigated binding specificity of the ETS-domains from two members of the ternary complex factor (TCF) subfamily, Elk-1 and SAP-1. The ETS DNA-binding domains of Elk-1 (Elk-93) and SAP-1 (SAP-92) select similar sites from random pools of double stranded oligonucleotides based on the consensus sequence ACCGGAAGTR. However, SAP-92 shows a more relaxed binding site selectivity and binds efficiently to a greater spectrum of sites than does Elk-93. This more relaxed DNA binding site selectivity is most pronounced in nucleotides located on the 3' side of the GGA motif. This differential DNA-binding specificity is also exhibited by longer TCF derivatives and, indeed by the full-length proteins. Our results suggest that the range of potential in vivo target sites for SAP-1 is likely to be greater than for Elk-1. We discuss our results in relation to other similar studies carried out with more divergent ETS-domains.


Assuntos
Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Animais , Sequência de Bases , Sítios de Ligação , Sequência Consenso , DNA/química , Primers do DNA , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/química , Humanos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Reação em Cadeia da Polimerase , Biossíntese de Proteínas , Proteínas Proto-Oncogênicas/biossíntese , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas c-ets , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Especificidade por Substrato , Fatores de Transcrição/metabolismo , Proteínas Elk-1 do Domínio ets , Proteínas Elk-4 do Domínio ets
13.
Nucleic Acids Res ; 23(13): 2442-9, 1995 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-7630721

RESUMO

Transcriptional induction of the c-fos proto-oncogene in response to serum growth factors is mediated in part by a ternary complex that forms on the serum response element (SRE) within its promoter. This complex consists of Elk-1, serum response factor (SRF) and the SRE. Elk-1 is phosphorylated by MAP kinase, which correlates with the induction of c-fos transcription. In this study we have investigated the protein-induced DNA bending which occurs during the formation and post-translational modification of the ternary complex that forms at the c-fos SRE. Circular permutation analysis demonstrates that the minimal DNA-binding domain of SRF, which contains the MADS box, is sufficient to induce flexibility into the centre of its binding site within the SRE. Phasing analysis indicates that at least part of this flexibility results in the production of a directional bend towards the minor groove. The isolated ETS domains from Elk-1 and SAP-1 induce neither DNA bending nor increased DNA flexibility. Formation of ternary complexes by binding of Elk-1 to the binary SRF:SRE complex results in a change in the flexibility of the SRE. Phosphorylation of Elk-1 by MAP kinase (p42/ERK2) induces further minor changes in this DNA flexibility. However, phasing analysis reveals that the recruitment of Elk-1 to form the ternary complex affects the SRF-induced directional DNA bend in the SRE. The potential roles of DNA bending at the c-fos SRE are discussed.


Assuntos
DNA/química , Genes fos , Conformação de Ácido Nucleico , Regiões Promotoras Genéticas , Fatores de Transcrição , Sequência de Bases , Sítios de Ligação , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Elementos Facilitadores Genéticos , Dados de Sequência Molecular , Proteínas Nucleares/metabolismo , Fosforilação , Processamento de Proteína Pós-Traducional , Proteínas Proto-Oncogênicas/metabolismo , Fator de Resposta Sérica , Proteínas Elk-1 do Domínio ets
14.
Science ; 269(5222): 403-7, 1995 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-7618106

RESUMO

The ternary complex factor (TCF) subfamily of ETS-domain transcription factors bind with serum response factor (SRF) to the serum response element (SRE) and mediate increased gene expression. The TCF protein Elk-1 is phosphorylated by the JNK and ERK groups of mitogen-activated protein (MAP) kinases causing increased DNA binding, ternary complex formation, and transcriptional activation. Activated SRE-dependent gene expression is induced by JNK in cells treated with interleukin-1 and by ERK after treatment with phorbol ester. The Elk-1 transcription factor therefore integrates MAP kinase signaling pathways in vivo to coordinate biological responses to different extracellular stimuli.


Assuntos
Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno , Proteínas Quinases Ativadas por Mitógeno , Proteínas Nucleares/metabolismo , Regiões Promotoras Genéticas , Transdução de Sinais , Animais , Células CHO , Cricetinae , Regulação da Expressão Gênica , Interleucina-1/farmacologia , Proteínas Quinases JNK Ativadas por Mitógeno , MAP Quinase Quinase 1 , Proteína Quinase 1 Ativada por Mitógeno , Proteína Quinase 3 Ativada por Mitógeno , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Fator de Resposta Sérica , Acetato de Tetradecanoilforbol/farmacologia , Fatores de Transcrição/metabolismo , Transfecção , Proteínas Elk-1 do Domínio ets , Proteínas Elk-4 do Domínio ets
15.
Eur J Biochem ; 229(1): 1-13, 1995 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-7744019

RESUMO

The MADS-box family of transcription factors has been defined on the basis of primary sequence similarity amongst numerous proteins from a diverse range of eukaryotic organisms including yeasts, plants, insects, amphibians and mammals. The MADS-box is a conserved motif found within the DNA-binding domains of these proteins and the name refers to four of the originally identified members: MCM1, AG, DEFA and SRF. Several proteins within this family have significant biological roles. For example, the human serum-response factor (SRF) is involved in co-ordinating transcription of the protooncogene c-fos, whilst MCM1 is central to the transcriptional control of cell-type specific genes and the pheromone response in the yeast Saccharomyces cerevisiae. The RSRF/MEF2 proteins comprise a sub-family of this class of transcription factors which are key components in muscle-specific gene regulation. Moreover, in plants, MADS-box proteins such as AG, DEFA and GLO play fundamental roles during flower development. The MADS-box is a contiguous conserved sequence of 56 amino acids, of which 9 are identical in all family members described so far. Several members have been shown to form dimers and consequently two functional regions within the MADS-box have been defined. The N-terminal half is the major determinant of DNA-binding specificity whilst the C-terminal half is necessary for dimerisation. This organisation allows the potential formation of numerous proteins, with subtly different DNA-binding specificities, from a limited number of genes by heterodimerisation between different MADS-box proteins. The majority of MADS-box proteins bind similar sites based on the consensus sequence CC(A/T)6GG although each protein apparently possesses a distinct binding specificity. Moreover, several MADS-box proteins specifically recruit other transcription factors into multi-component regulatory complexes. Such interactions with other proteins appears to be a common theme within this family and play a pivotal role in the regulation of target genes.


Assuntos
Fatores de Transcrição/genética , Sequência de Aminoácidos , Animais , Sequência Conservada , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica , Dados de Sequência Molecular , Saccharomyces cerevisiae/genética , Alinhamento de Sequência , Transcrição Gênica/genética
16.
J Biol Chem ; 270(11): 5805-11, 1995 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-7890710

RESUMO

The ETS domain family of transcription factors is comprised of several important proteins that are involved in controlling key cellular events such as proliferation, differentiation, and development. One such protein, Elk-1, regulates the activity of the c-fos promoter in response to extracellular stimuli. Elk-1 is representative of a subgroup of ETS domain proteins that utilize a bipartite recognition mechanism that is mediated by both protein-DNA and protein-protein interactions. In this study, we have overexpressed, purified, and characterized the ETS DNA-binding domain of Elk-1 (Elk-93). Elk-93 was expressed in Escherichia coli as a fusion protein with glutathione S-transferase and purified to homogeneity from both the soluble and insoluble fractions using a two-column protocol. A combination of CD, NMR, and fluorescence spectroscopy demonstrates that Elk-93 represents an independently folded domain of mixed alpha/beta structure in which the three conserved tryptophans appear to contribute to the hydrophobic core of the protein. Moreover, DNA binding studies demonstrate that Elk-93 binds DNA with both high affinity (Kd approximately 0.85 x 10(-10)M) and specificity. Circular permutation analysis indicates that DNA binding by Elk-93 does not induce significant bending of the DNA. Our results are discussed with respect to predictive models for the structure of the ETS DNA-binding domain.


Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Estrutura Secundária de Proteína , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas/metabolismo , Animais , Sequência de Bases , Sítios de Ligação , Dicroísmo Circular , Clonagem Molecular , DNA/isolamento & purificação , DNA/metabolismo , Primers do DNA , Proteínas de Ligação a DNA/isolamento & purificação , Escherichia coli , Genes fos , Glutationa Transferase/metabolismo , Cinética , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , Dobramento de Proteína , Proteínas Proto-Oncogênicas/isolamento & purificação , Proteínas Proto-Oncogênicas c-ets , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/metabolismo , Espectrometria de Fluorescência , Especificidade por Substrato , Fatores de Transcrição/metabolismo , Proteínas Elk-1 do Domínio ets
17.
FEBS Lett ; 355(1): 57-60, 1994 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-7957963

RESUMO

Enzyme-catalysed DNA methylation provides an opportunity for the modulation of protein-DNA recognition in biological systems. Recently we have demonstrated that the smaller of the two subunits of the heterodimeric, cytosine-specific DNA methyltransferase, M. AquI, is largely responsible for sequence-specific DNA recognition. Here we present evidence from a series of NMR, fluorescence and circular dichroism spectroscopy experiments that the DNA binding subunit of M. AquI has the characteristics of a molten globule in the absence of the catalytic machinery. In this metastable state this subunit retains its ability to bind DNA in a sequence-specific manner. We believe this finding offers an insight into the structural flexibility which underpins the mechanism of action of these enzymes, and may provide a possible biological role for molten globules in protein function.


Assuntos
Proteínas de Transporte/genética , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Membrana/genética , Metamorfose Biológica , Hormônios Tireóideos , Sequência de Aminoácidos , Animais , Proteínas de Transporte/química , Clonagem Molecular , Citosol , Extremidades/crescimento & desenvolvimento , Humanos , Mucosa Intestinal/metabolismo , Intestinos/crescimento & desenvolvimento , Proteínas de Membrana/química , Dados de Sequência Molecular , Morfogênese , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos , Cauda/crescimento & desenvolvimento , Cauda/metabolismo , Xenopus laevis , Proteínas de Ligação a Hormônio da Tireoide
18.
Mol Cell Biol ; 14(5): 3283-91, 1994 May.
Artigo em Inglês | MEDLINE | ID: mdl-8164681

RESUMO

Transcriptional induction of the c-fos gene in response to epidermal growth factor stimulation is mediated in part by a ternary nucleoprotein complex within the promoter consisting of serum response factor (SRF), p62TCF/Elk-1 and the serum response element (SRE). Both SRF and p62TCF/Elk-1 contact the DNA and bind in a cooperative manner to the SRE. In this study, we demonstrate that SRF and Elk-1 interact directly in the absence of the SRE. A 30-amino-acid peptide from Elk-1 (B-box) is both necessary and sufficient to mediate protein-protein contacts with SRF. Moreover, the Elk-1 B-box is necessary to enable SRF-dependent binding of an alternative ETS domain (from the transcription factor PU.1) to the c-fos SRE. Mutations in either the Elk-1 B-box or the C-terminal half of the SRF DNA-binding domain (coreSRF) which show reduced ability to form ternary complexes also show greatly reduced protein-protein interactions in the absence of the SRE. Our results clearly demonstrate that direct protein-protein interactions between the transcription factors Elk-1 and SRF, in addition to DNA contacts, contribute to the formation of a ternary complex on the c-fos SRE. We discuss the wider applicability of our results in describing specific protein-protein interactions between short well-defined transcription factor domains.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Fator de Crescimento Epidérmico/farmacologia , Regulação da Expressão Gênica , Genes fos , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas , Proteínas Oncogênicas de Retroviridae/metabolismo , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Sítios de Ligação , DNA/metabolismo , Primers do DNA , Proteínas de Ligação a DNA/biossíntese , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Proteínas Nucleares/biossíntese , Oligodesoxirribonucleotídeos , Plasmídeos , Mutação Puntual , Reação em Cadeia da Polimerase , Ligação Proteica , Biossíntese de Proteínas , Proteínas Oncogênicas de Retroviridae/biossíntese , Proteínas Oncogênicas de Retroviridae/química , Saccharomyces cerevisiae/metabolismo , Homologia de Sequência de Aminoácidos , Fator de Resposta Sérica , Transcrição Gênica , Proteínas Elk-1 do Domínio ets
20.
Methods Mol Biol ; 11: 273-86, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-21431673

RESUMO

It is the exquisite interplay of proteins and nucleic acids within the cell which gives rise to the controlled expression and replication of the genetic material. Our present understanding of these processes is in part the result of the successful purification and characterization of the participating macromolecules. The achievements of the early molecular biologists in obtaining active, homogeneous preparations of low-abundance gene regulatory proteins are outstanding. The strategies employed for the purification of such proteins are, however, no different in principle to those procedures used to purify high-abundance proteins. Moreover, one of the goals of molecular biologists in purifying gene regulatory proteins is to clone the corresponding gene. When this has been achieved, the gene can often be overexpressed, and the purification of the gene product becomes trivial by comparison.

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