Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Mol Cell ; 59(6): 984-97, 2015 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-26321255

RESUMO

Transcriptionally active and inactive chromatin domains tend to segregate into separate sub-nuclear compartments to maintain stable expression patterns. However, here we uncovered an inter-chromosomal network connecting active loci enriched in circadian genes to repressed lamina-associated domains (LADs). The interactome is regulated by PARP1 and its co-factor CTCF. They not only mediate chromatin fiber interactions but also promote the recruitment of circadian genes to the lamina. Synchronization of the circadian rhythm by serum shock induces oscillations in PARP1-CTCF interactions, which is accompanied by oscillating recruitment of circadian loci to the lamina, followed by the acquisition of repressive H3K9me2 marks and transcriptional attenuation. Furthermore, depletion of H3K9me2/3, inhibition of PARP activity by olaparib, or downregulation of PARP1 or CTCF expression counteracts both recruitment to the envelope and circadian transcription. PARP1- and CTCF-regulated contacts between circadian loci and the repressive chromatin environment at the lamina therefore mediate circadian transcriptional plasticity.


Assuntos
Cromatina/genética , Células-Tronco Embrionárias Humanas/enzimologia , Poli(ADP-Ribose) Polimerases/metabolismo , Proteínas Repressoras/metabolismo , Transcrição Gênica , Proteínas Adaptadoras de Transdução de Sinal , Fator de Ligação a CCCTC , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Imunoprecipitação da Cromatina , Ritmo Circadiano , Corpos Embrioides/enzimologia , Epistasia Genética , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Células HCT116 , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Lâmina Nuclear/metabolismo , Poli(ADP-Ribose) Polimerase-1 , Ligação Proteica , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo
2.
Nat Methods ; 10(5): 407-9, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23524392

RESUMO

We report a monomeric yellow-green fluorescent protein, mNeonGreen, derived from a tetrameric fluorescent protein from the cephalochordate Branchiostoma lanceolatum. mNeonGreen is the brightest monomeric green or yellow fluorescent protein yet described to our knowledge, performs exceptionally well as a fusion tag for traditional imaging as well as stochastic single-molecule superresolution imaging and is an excellent fluorescence resonance energy transfer (FRET) acceptor for the newest cyan fluorescent proteins.


Assuntos
Cordados/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Animais , Dados de Sequência Molecular , Processos Estocásticos
3.
Nat Cell Biol ; 8(4): 391-7, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16518390

RESUMO

Guard cells, which form stomata in leaf epidermes, sense a multitude of environmental signals and integrate this information to regulate stomatal movements. Compared with the advanced understanding of light and water stress responses in guard cells, the molecular mechanisms that underlie stomatal CO(2) signalling have remained relatively obscure. With a high-throughput leaf thermal imaging CO(2) screen, we report the isolation of two allelic Arabidopsis mutants (high leaf temperature 1; ht1-1 and ht1-2) that are altered in their ability to control stomatal movements in response to CO(2). The strong allele, ht1-2, exhibits a markedly impaired CO(2) response but shows functional responses to blue light, fusicoccin and abscisic acid (ABA), indicating a role for HT1 in stomatal CO(2) signalling. HT1 encodes a protein kinase that is expressed mainly in guard cells. Phosphorylation assays demonstrate that the activity of the HT1 protein carrying the ht1-1 or ht1-2 mutation is greatly impaired or abolished, respectively. Furthermore, dominant-negative HT1(K113W) transgenic plants, which lack HT1 kinase activity, show a disrupted CO(2) response. These findings indicate that the HT1 kinase is important for regulation of stomatal movements and its function is more pronounced in response to CO(2) than it is to ABA or light.


Assuntos
Arabidopsis/enzimologia , Dióxido de Carbono/metabolismo , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Proteínas Quinases/metabolismo , Ácido Abscísico/farmacologia , Genes Dominantes , Glicosídeos/farmacologia , Luz , Mutação , Fosforilação , Plantas Geneticamente Modificadas , Proteínas Quinases/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais
4.
Curr Opin Plant Biol ; 9(6): 654-63, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17010657

RESUMO

Stomatal pores in the epidermis of plants enable gas exchange between plants and the atmosphere, a process vital to plant life. Pairs of specialized guard cells surround and control stomatal apertures. Stomatal closing is induced by abscisic acid (ABA) and elevated CO(2) concentrations. Recent advances have been made in understanding ABA signaling and in characterizing CO(2) transduction mechanisms and CO(2) signaling mutants. In addition, models of Ca(2+)-dependent and Ca(2+)-independent signaling in guard cells have been developed and a new hypothesis has been formed in which physiological stimuli are proposed to prime Ca(2+) sensors, thus enabling specificity in Ca(2+)-dependent signal transduction.


Assuntos
Ácido Abscísico/metabolismo , Cálcio/metabolismo , Dióxido de Carbono/metabolismo , Folhas de Planta/citologia , Folhas de Planta/metabolismo , Transdução de Sinais
5.
Proc Natl Acad Sci U S A ; 103(19): 7506-11, 2006 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-16651523

RESUMO

Leaf stomata close in response to high carbon dioxide levels and open at low CO(2). CO(2) concentrations in leaves are altered by daily dark/light cycles, as well as the continuing rise in atmospheric CO(2). Relative to abscisic acid and blue light signaling, little is known about the molecular, cellular, and genetic mechanisms of CO(2) signaling in guard cells. Interestingly, we report that repetitive Ca(2+) transients were observed during the stomatal opening stimulus, low [CO(2)]. Furthermore, low/high [CO(2)] transitions modulated the cytosolic Ca(2+) transient pattern in Arabidopsis guard cells (Landsberg erecta). Inhibition of cytosolic Ca(2+) transients, achieved by loading guard cells with the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid and not adding external Ca(2+), attenuated both high CO(2)-induced stomatal closing and low CO(2)-induced stomatal opening, and also revealed a Ca(2+)-independent phase of the CO(2) response. Furthermore, the mutant, growth controlled by abscisic acid (gca2) shows impairment in [CO(2)] modulation of the cytosolic Ca(2+) transient rate and strong impairment in high CO(2)-induced stomatal closing. Our findings provide insights into guard cell CO(2) signaling mechanisms, reveal Ca(2+)-independent events, and demonstrate that calcium elevations can participate in opposed signaling events during stomatal opening and closing. A model is proposed in which CO(2) concentrations prime Ca(2+) sensors, which could mediate specificity in Ca(2+) signaling.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Cálcio/metabolismo , Dióxido de Carbono/metabolismo , Transdução de Sinais , Ácido Abscísico/farmacologia , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Dióxido de Carbono/farmacologia , Citosol/metabolismo , Mutação/genética
6.
Plant J ; 44(3): 494-504, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16236158

RESUMO

Bioactive gibberellins (GAs) are known regulators of shoot growth and development in plants. In an attempt to identify where GAs are formed, we have analyzed the expression patterns of six GA biosynthesis genes and two genes with predicted roles in GA signaling and responses in relation to measured levels of GAs. The analysis was based on tangential sections, giving tissue-specific resolution across the cambial region of aspen trees (Populus tremula). Gibberellin quantification by GC/MS-SRM showed that the bioactive GA1 and GA4 were predominantly located in the zone of expansion of xylem cells. Based on co-localization of the expression of the late GA biosynthesis gene GA 20-oxidase 1 and bioactive GAs, we suggest that de novo GA biosynthesis occurs in the expanding xylem. However, expression levels of the first committed GA biosynthesis enzyme, ent-copalyl diphosphate synthase, were high in the phloem, suggesting that a GA precursor(s) may be transported to the xylem. The expression of the GA signaling and response genes DELLA-like1 and GIP-like1 coincided well with sites of high bioactive GA levels. We therefore suggest that the main role of GA during wood formation is to regulate early stages of xylem differentiation, including cell elongation.


Assuntos
Regulação da Expressão Gênica de Plantas/genética , Giberelinas/metabolismo , Populus/genética , Populus/metabolismo , Transdução de Sinais/genética , Madeira , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Giberelinas/biossíntese , Ácidos Indolacéticos/metabolismo , Especificidade de Órgãos , Populus/anatomia & histologia , Populus/citologia
7.
Plant Mol Biol ; 52(4): 893-903, 2003 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-13677475

RESUMO

Transgenic lines of hybrid aspen with elevated levels of gibberellin (GA) show greatly increased numbers of xylem fibres and increases in xylem fibre length. These plants therefore provide excellent models for studying secondary growth. We have used cDNA microarry analysis to investigate how gene transcription in the developing xylem is affected by GA-induced growth. A recent investigation has shown that genes encoding lignin and cellulose biosynthetic enzymes, as well as a number of transcription factors and other potential regulators of xylogenesis, are under developmental-stage-specific transcriptional control. The present study shows that the highest transcript changes in our transgenic trees occurs in genes generally restricted to the early stages of xylogenesis, including cell division, early expansion and late expansion. The results reveal genes among those arrayed that are up-regulated with an increased xylem production, thus indicating key components in the production of wood.


Assuntos
Vigor Híbrido/genética , Estruturas Vegetais/genética , Populus/genética , Parede Celular/metabolismo , Regulação para Baixo , Flavonoides/biossíntese , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Giberelinas/metabolismo , Giberelinas/farmacologia , Hibridização Genética , Lignina/biossíntese , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estruturas Vegetais/crescimento & desenvolvimento , Estruturas Vegetais/metabolismo , Plantas Geneticamente Modificadas , Populus/crescimento & desenvolvimento , Populus/metabolismo , Xilanos/biossíntese
8.
Plant Physiol ; 135(1): 221-30, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15122019

RESUMO

To broaden our understanding of gibberellin (GA) biosynthesis and the mechanism whereby GA homeostasis is maintained in plants, we have investigated the degree to which the enzyme GA 3-oxidase (GA3ox) limits the formation of bioactive GAs in elongating shoots of hybrid aspen (Populus tremula x Populus tremuloides). We describe the cloning of a hybrid aspen GA3ox and its functional characterization, which confirmed that it has 3beta-hydroxylation activity and more efficiently converts GA9 to GA4 than GA20 to GA1. To complement previous studies, in which transgenic GA 20-oxidase (GA20ox) overexpressers were found to produce 20-fold higher bioactive GA levels and subsequently grew faster than wild-type plants, we overexpressed an Arabidopsis GA3ox in hybrid aspen. The generated GA3ox overexpresser lines had increased 3beta-hydroxylation activity but exhibited no major changes in morphology. The nearly unaltered growth pattern was associated with relatively small changes in GA1 and GA4 levels, although tissue-dependent differences were observed. The absence of increases in bioactive GA levels did not appear to be due to feedback or feed-forward regulation of dioxygenase transcripts, according to semiquantitative reverse transcription polymerase chain reaction analysis of PttGA20ox1, PttGA3ox1, and two putative PttGA2ox genes. We conclude that 20-oxidation is the limiting step, rather than 3beta-hydroxylation, in the formation of GA1 and GA4 in elongating shoots of hybrid aspen, and that ectopic GA3ox expression alone cannot increase the flux toward bioactive GAs. Finally, several lines of evidence now suggest that GA4 has a more pivotal role in the tree hybrid aspen than previously believed.


Assuntos
Giberelinas/metabolismo , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Populus/enzimologia , Clonagem Molecular , DNA Complementar/química , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Giberelinas/biossíntese , Homeostase , Hibridização Genética , Dados de Sequência Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Populus/genética , Populus/crescimento & desenvolvimento , Análise de Sequência de DNA
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA