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1.
Mol Cell ; 78(1): 127-140.e7, 2020 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-32035037

RESUMO

As cells enter mitosis, the genome is restructured to facilitate chromosome segregation, accompanied by dramatic changes in gene expression. However, the mechanisms that underlie mitotic transcriptional regulation are unclear. In contrast to transcribed genes, centromere regions retain transcriptionally active RNA polymerase II (Pol II) in mitosis. Here, we demonstrate that chromatin-bound cohesin is necessary to retain elongating Pol II at centromeres. We find that WAPL-mediated removal of cohesin from chromosome arms during prophase is required for the dissociation of Pol II and nascent transcripts, and failure of this process dramatically alters mitotic gene expression. Removal of cohesin/Pol II from chromosome arms in prophase is important for accurate chromosome segregation and normal activation of gene expression in G1. We propose that prophase cohesin removal is a key step in reprogramming gene expression as cells transition from G2 through mitosis to G1.


Assuntos
Proteínas de Ciclo Celular/fisiologia , Proteínas Cromossômicas não Histona/fisiologia , Regulação da Expressão Gênica , Mitose/genética , Transcrição Gênica , Anáfase/genética , Animais , Aurora Quinase B/análise , Ciclo Celular , Proteínas de Ciclo Celular/análise , Linhagem Celular , Centrômero/enzimologia , Segregação de Cromossomos , Fase G1/genética , Pontos de Checagem da Fase G2 do Ciclo Celular/genética , Humanos , Metáfase/genética , Prófase , RNA Polimerase II/metabolismo , Xenopus laevis , Coesinas
2.
Mol Cell ; 80(6): 1104-1122.e9, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33259812

RESUMO

Human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causative pathogen of the COVID-19 pandemic, exerts a massive health and socioeconomic crisis. The virus infects alveolar epithelial type 2 cells (AT2s), leading to lung injury and impaired gas exchange, but the mechanisms driving infection and pathology are unclear. We performed a quantitative phosphoproteomic survey of induced pluripotent stem cell-derived AT2s (iAT2s) infected with SARS-CoV-2 at air-liquid interface (ALI). Time course analysis revealed rapid remodeling of diverse host systems, including signaling, RNA processing, translation, metabolism, nuclear integrity, protein trafficking, and cytoskeletal-microtubule organization, leading to cell cycle arrest, genotoxic stress, and innate immunity. Comparison to analogous data from transformed cell lines revealed respiratory-specific processes hijacked by SARS-CoV-2, highlighting potential novel therapeutic avenues that were validated by a high hit rate in a targeted small molecule screen in our iAT2 ALI system.


Assuntos
Células Epiteliais Alveolares/metabolismo , COVID-19/metabolismo , Fosfoproteínas/metabolismo , Proteoma/metabolismo , SARS-CoV-2/metabolismo , Células Epiteliais Alveolares/patologia , Células Epiteliais Alveolares/virologia , Animais , Antivirais , COVID-19/genética , COVID-19/patologia , Chlorocebus aethiops , Efeito Citopatogênico Viral , Citoesqueleto , Avaliação Pré-Clínica de Medicamentos , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Pluripotentes Induzidas/patologia , Células-Tronco Pluripotentes Induzidas/virologia , Fosfoproteínas/genética , Transporte Proteico , Proteoma/genética , SARS-CoV-2/genética , Transdução de Sinais , Células Vero , Tratamento Farmacológico da COVID-19
3.
Plant Cell ; 33(7): 2431-2453, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-33944955

RESUMO

Endoplasmic reticulum-plasma membrane contact sites (ER-PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis thaliana mutants lacking the ER-PM protein tether synaptotagmin1 (SYT1) exhibit decreased PM integrity under multiple abiotic stresses, such as freezing, high salt, osmotic stress, and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER-PM tether that also functions in maintaining PM integrity. The ER-PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to wild-type while the levels of most glycerolipid species remain unchanged. In addition, the SYT1-green fluorescent protein fusion preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Membrana Celular/metabolismo , Diglicerídeos/metabolismo , Retículo Endoplasmático/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo
5.
J Biol Chem ; 296: 100202, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33334895

RESUMO

Elongin A (EloA) is an essential transcription factor that stimulates the rate of RNA polymerase II (Pol II) transcription elongation in vitro. However, its role as a transcription factor in vivo has remained underexplored. Here we show that in mouse embryonic stem cells, EloA localizes to both thousands of Pol II transcribed genes with preference for transcription start site and promoter regions and a large number of active enhancers across the genome. EloA deletion results in accumulation of transcripts from a subset of enhancers and their adjacent genes. Notably, EloA does not substantially enhance the elongation rate of Pol II in vivo. We also show that EloA localizes to the nucleoli and associates with RNA polymerase I transcribed ribosomal RNA gene, Rn45s. EloA is a highly disordered protein, which we demonstrate forms phase-separated condensates in vitro, and truncation mutations in the intrinsically disordered regions (IDR) of EloA interfere with its targeting and localization to the nucleoli. We conclude that EloA broadly associates with transcribed regions, tunes RNA Pol II transcription levels via impacts on enhancer RNA synthesis, and interacts with the rRNA producing/processing machinery in the nucleolus. Our work opens new avenues for further investigation of the role of this functionally multifaceted transcription factor in enhancer and ribosomal RNA biology.


Assuntos
Elonguina/metabolismo , Elementos Facilitadores Genéticos , Células-Tronco Embrionárias Murinas/metabolismo , RNA/genética , Ativação Transcricional , Animais , Linhagem Celular , Elonguina/genética , Deleção de Genes , Camundongos , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Sítio de Iniciação de Transcrição
6.
Nucleic Acids Res ; 48(11): 6280-6293, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32396196

RESUMO

Although originally identified as the components of the complex aiding the cytosolic chaperonin CCT in the folding of actins and tubulins in the cytosol, prefoldins (PFDs) are emerging as novel regulators influencing gene expression in the nucleus. Work conducted mainly in yeast and animals showed that PFDs act as transcriptional regulators and participate in the nuclear proteostasis. To investigate new functions of PFDs, we performed a co-expression analysis in Arabidopsis thaliana. Results revealed co-expression between PFD and the Sm-like (LSM) genes, which encode the LSM2-8 spliceosome core complex, in this model organism. Here, we show that PFDs interact with and are required to maintain adequate levels of the LSM2-8 complex. Our data indicate that levels of the LSM8 protein, which defines and confers the functional specificity of the complex, are reduced in pfd mutants and in response to the Hsp90 inhibitor geldanamycin. We provide biochemical evidence showing that LSM8 is a client of Hsp90 and that PFD4 mediates the interaction between both proteins. Consistent with our results and with the role of the LSM2-8 complex in splicing through the stabilization of the U6 snRNA, pfd mutants showed reduced levels of this snRNA and altered pre-mRNA splicing patterns.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Chaperonas Moleculares/metabolismo , Complexos Multiproteicos/metabolismo , Proteínas de Ligação a RNA/metabolismo , Spliceossomos/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Complexos Multiproteicos/química , Mutação , Ligação Proteica , Splicing de RNA , Spliceossomos/química
7.
J Exp Bot ; 70(12): 3283-3296, 2019 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-30869795

RESUMO

Plant tolerance to freezing temperatures is governed by endogenous components and environmental factors. Exposure to low non-freezing temperatures is a key factor in the induction of freezing tolerance in the process called cold acclimation. The role of nitric oxide (NO) in cold acclimation was explored in Arabidopsis using triple nia1nia2noa1-2 mutants that are impaired in the nitrate-dependent and nitrate-independent pathways of NO production, and are thus NO deficient. Here, we demonstrate that cold-induced NO accumulation is required to promote the full cold acclimation response through C-repeat Binding Factor (CBF)-dependent gene expression, as well as the CBF-independent expression of other cold-responsive genes such as Oxidation-Related Zinc Finger 2 (ZF/OZF2). NO deficiency also altered abscisic acid perception and signaling and the cold-induced production of anthocyanins, which are additional factors involved in cold acclimation.


Assuntos
Aclimatação , Arabidopsis/fisiologia , Temperatura Baixa , Óxido Nítrico/deficiência , Arabidopsis/genética , Mutação
8.
Plant Cell ; 28(2): 505-20, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26764377

RESUMO

In eukaryotes, the decapping machinery is highly conserved and plays an essential role in controlling mRNA stability, a key step in the regulation of gene expression. Yet, the role of mRNA decapping in shaping gene expression profiles in response to environmental cues and the operating molecular mechanisms are poorly understood. Here, we provide genetic and molecular evidence that a component of the decapping machinery, the LSM1-7 complex, plays a critical role in plant tolerance to abiotic stresses. Our results demonstrate that, depending on the stress, the complex from Arabidopsis thaliana interacts with different selected stress-inducible transcripts targeting them for decapping and subsequent degradation. This interaction ensures the correct turnover of the target transcripts and, consequently, the appropriate patterns of downstream stress-responsive gene expression that are required for plant adaptation. Remarkably, among the selected target transcripts of the LSM1-7 complex are those encoding NCED3 and NCED5, two key enzymes in abscisic acid (ABA) biosynthesis. We demonstrate that the complex modulates ABA levels in Arabidopsis exposed to cold and high salt by differentially controlling NCED3 and NCED5 mRNA turnover, which represents a new layer of regulation in ABA biosynthesis in response to abiotic stress. Our findings uncover an unanticipated functional plasticity of the mRNA decapping machinery to modulate the relationship between plants and their environment.


Assuntos
Adaptação Fisiológica , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Endorribonucleases/metabolismo , Regulação da Expressão Gênica de Plantas , Modelos Biológicos , Ácido Abscísico/metabolismo , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Temperatura Baixa , Endorribonucleases/genética , Genes Reporter , Reguladores de Crescimento de Plantas/metabolismo , Plantas Geneticamente Modificadas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Cloreto de Sódio/metabolismo , Estresse Fisiológico
9.
Nucleic Acids Res ; 45(12): 7416-7431, 2017 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-28482101

RESUMO

Spliceosome activity is tightly regulated to ensure adequate splicing in response to internal and external cues. It has been suggested that core components of the spliceosome, such as the snRNPs, would participate in the control of its activity. The experimental indications supporting this proposition, however, remain scarce, and the operating mechanisms poorly understood. Here, we present genetic and molecular evidence demonstrating that the LSM2-8 complex, the protein moiety of the U6 snRNP, regulates the spliceosome activity in Arabidopsis, and that this regulation is controlled by the environmental conditions. Our results show that the complex ensures the efficiency and accuracy of constitutive and alternative splicing of selected pre-mRNAs, depending on the conditions. Moreover, miss-splicing of most targeted pre-mRNAs leads to the generation of nonsense mediated decay signatures, indicating that the LSM2-8 complex also guarantees adequate levels of the corresponding functional transcripts. Interestingly, the selective role of the complex has relevant physiological implications since it is required for adequate plant adaptation to abiotic stresses. These findings unveil an unanticipated function for the LSM2-8 complex that represents a new layer of posttranscriptional regulation in response to external stimuli in eukaryotes.


Assuntos
Processamento Alternativo , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Precursores de RNA/genética , RNA Nuclear Pequeno/genética , Proteínas de Ligação a RNA/genética , Spliceossomos/química , Adaptação Fisiológica/genética , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Temperatura Baixa , Regulação da Expressão Gênica de Plantas , Degradação do RNAm Mediada por Códon sem Sentido , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Precursores de RNA/metabolismo , Estabilidade de RNA , RNA Nuclear Pequeno/metabolismo , Proteínas de Ligação a RNA/metabolismo , Cloreto de Sódio/farmacologia , Spliceossomos/efeitos dos fármacos , Spliceossomos/metabolismo , Estresse Fisiológico
10.
Plant Cell ; 24(12): 4930-47, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23221597

RESUMO

In yeast and animals, SM-like (LSM) proteins typically exist as heptameric complexes and are involved in different aspects of RNA metabolism. Eight LSM proteins, LSM1 to 8, are highly conserved and form two distinct heteroheptameric complexes, LSM1-7 and LSM2-8,that function in mRNA decay and splicing, respectively. A search of the Arabidopsis thaliana genome identifies 11 genes encoding proteins related to the eight conserved LSMs, the genes encoding the putative LSM1, LSM3, and LSM6 proteins being duplicated. Here, we report the molecular and functional characterization of the Arabidopsis LSM gene family. Our results show that the 11 LSM genes are active and encode proteins that are also organized in two different heptameric complexes. The LSM1-7 complex is cytoplasmic and is involved in P-body formation and mRNA decay by promoting decapping. The LSM2-8 complex is nuclear and is required for precursor mRNA splicing through U6 small nuclear RNA stabilization. More importantly, our results also reveal that these complexes are essential for the correct turnover and splicing of selected development-related mRNAs and for the normal development of Arabidopsis. We propose that LSMs play a critical role in Arabidopsis development by ensuring the appropriate development-related gene expression through the regulation of mRNA splicing and decay.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/metabolismo , Genoma de Planta/genética , Splicing de RNA/genética , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Estabilidade de RNA/genética , RNA Mensageiro/genética
11.
Trends Cell Biol ; 31(9): 760-773, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33766521

RESUMO

Beyond its originally discovered role tethering replicated sister chromatids, cohesin has emerged as a master regulator of gene expression. Recent advances in chromatin topology resolution and single-cell studies have revealed that cohesin has a pivotal role regulating highly dynamic chromatin interactions linked to transcription control. The dynamic association of cohesin with chromatin and its capacity to perform loop extrusion contribute to the heterogeneity of chromatin contacts. Additionally, different cohesin subcomplexes, with specific properties and regulation, control gene expression across the cell cycle and during developmental cell commitment. Here, we discuss the most recent literature in the field to highlight the role of cohesin in gene expression regulation during transcriptional shifts and its relationship with human diseases.


Assuntos
Proteínas de Ciclo Celular , Proteínas Cromossômicas não Histona , Proteínas de Ciclo Celular/genética , Cromátides , Cromatina/genética , Proteínas Cromossômicas não Histona/genética , Expressão Gênica , Humanos , Coesinas
12.
Cell Rep ; 35(11): 109263, 2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-34133931

RESUMO

The interplay between the phytohormone abscisic acid (ABA) and the gasotransmitter nitric oxide (NO) regulates seed germination and post-germinative seedling growth. We show that GAP1 (germination in ABA and cPTIO 1) encodes the transcription factor ANAC089 with a critical membrane-bound domain and extranuclear localization. ANAC089 mutants lacking the membrane-tethered domain display insensitivity to ABA, salt, and osmotic and cold stresses, revealing a repressor function. Whole-genome transcriptional profiling and DNA-binding specificity reveals that ANAC089 regulates ABA- and redox-related genes. ANAC089 truncated mutants exhibit higher NO and lower ROS and ABA endogenous levels, alongside an altered thiol and disulfide homeostasis. Consistently, translocation of ANAC089 to the nucleus is directed by changes in cellular redox status after treatments with NO scavengers and redox-related compounds. Our results reveal ANAC089 to be a master regulator modulating redox homeostasis and NO levels, able to repress ABA synthesis and signaling during Arabidopsis seed germination and abiotic stress.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Retroalimentação Fisiológica , Germinação , Sementes , Transdução de Sinais , Estresse Fisiológico , Ácido Abscísico/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Sequência de Bases , Sítios de Ligação , Dissulfetos/metabolismo , DNA de Plantas/metabolismo , Regulação para Baixo/genética , Mutação com Ganho de Função/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Germinação/genética , Óxido Nítrico/metabolismo , Oxirredução , Ligação Proteica , Sementes/genética , Sementes/crescimento & desenvolvimento , Frações Subcelulares/metabolismo , Compostos de Sulfidrila/metabolismo , Transcriptoma/genética , Regulação para Cima/genética
13.
Methods Mol Biol ; 2156: 85-97, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32607977

RESUMO

Low temperature is an important determinant in the configuration of natural plant communities and defines the range of distribution and growth of important crops. Some plants, including Arabidopsis thaliana, have evolved sophisticated adaptive mechanisms to tolerate freezing temperatures. Central to this adaptation is the process of cold acclimation. By means of this process, many plants from temperate regions are able to develop or increase their freezing tolerance in response to low, nonfreezing temperatures. The identification and characterization of factors involved in freezing tolerance is crucial to understand the molecular mechanisms underlying the cold acclimation response and has a potential interest to improve crop tolerance to freezing temperatures. Many genes implicated in cold acclimation have been identified in numerous plant species by using molecular approaches followed by reverse genetic analysis. Remarkably, however, direct genetic analyses have not been conveniently exploited in their capacity for identifying genes with pivotal roles in that adaptive response. In this chapter, we describe a protocol for evaluating the freezing tolerance of both nonacclimated and cold acclimated Arabidopsis plants. This protocol allows for the accurate and simple screening of mutant collections for the identification of novel factors involved in freezing tolerance and cold acclimation.


Assuntos
Aclimatação/genética , Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Congelamento , Mutação , Temperatura Baixa , Ambiente Controlado , Regulação da Expressão Gênica de Plantas , Mutagênese , Fenótipo , Melhoramento Vegetal , Desenvolvimento Vegetal/genética
14.
J Cell Biol ; 219(11)2020 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-33053167

RESUMO

During mitosis, the genome is transformed from a decondensed, transcriptionally active state to a highly condensed, transcriptionally inactive state. Mitotic chromosome reorganization is marked by the general attenuation of transcription on chromosome arms, yet how the cell regulates nuclear and chromatin-associated RNAs after chromosome condensation and nuclear envelope breakdown is unknown. SAF-A/hnRNPU is an abundant nuclear protein with RNA-to-DNA tethering activity, coordinated by two spatially distinct nucleic acid-binding domains. Here we show that RNA is evicted from prophase chromosomes through Aurora-B-dependent phosphorylation of the SAF-A DNA-binding domain; failure to execute this pathway leads to accumulation of SAF-A-RNA complexes on mitotic chromosomes, defects in metaphase chromosome alignment, and elevated rates of chromosome missegregation in anaphase. This work reveals a role for Aurora-B in removing chromatin-associated RNAs during prophase and demonstrates that Aurora-B-dependent relocalization of SAF-A during cell division contributes to the fidelity of chromosome segregation.


Assuntos
Aurora Quinase B/metabolismo , Núcleo Celular/genética , Cromatina/química , Cromossomos Humanos/química , Ribonucleoproteínas Nucleares Heterogêneas Grupo U/metabolismo , Mitose , RNA/metabolismo , Aurora Quinase B/genética , Cromatina/genética , Cromossomos Humanos/genética , Células HEK293 , Ribonucleoproteínas Nucleares Heterogêneas Grupo U/genética , Humanos , Fosforilação , RNA/genética
15.
Front Plant Sci ; 10: 167, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30873189

RESUMO

It has long been assumed that the wide reprogramming of gene expression that modulates plant response to unfavorable environmental conditions is mainly controlled at the transcriptional level. A growing body of evidence, however, indicates that posttranscriptional regulatory mechanisms also play a relevant role in this control. Thus, the LSMs, a family of proteins involved in mRNA metabolism highly conserved in eukaryotes, have emerged as prominent regulators of plant tolerance to abiotic stress. Arabidopsis contains two main LSM ring-shaped heteroheptameric complexes, LSM1-7 and LSM2-8, with different subcellular localization and function. The LSM1-7 ring is part of the cytoplasmic decapping complex that regulates mRNA stability. On the other hand, the LSM2-8 complex accumulates in the nucleus to ensure appropriate levels of U6 snRNA and, therefore, correct pre-mRNA splicing. Recent studies reported unexpected results that led to a fundamental change in the assumed consideration that LSM complexes are mere components of the mRNA decapping and splicing cellular machineries. Indeed, these data have demonstrated that LSM1-7 and LSM2-8 rings operate in Arabidopsis by selecting specific RNA targets, depending on the environmental conditions. This specificity allows them to actively imposing particular gene expression patterns that fine-tune plant responses to abiotic stresses. In this review, we will summarize current and past knowledge on the role of LSM rings in modulating plant physiology, with special focus on their function in abiotic stress responses.

16.
Mol Cell Biol ; 38(18)2018 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-29941491

RESUMO

Accurate chromosome segregation is a fundamental process in cell biology. During mitosis, chromosomes are segregated into daughter cells through interactions between centromeres and microtubules in the mitotic spindle. Centromere domains have evolved to nucleate formation of the kinetochore, which is essential for establishing connections between chromosomal DNA and microtubules during mitosis. Centromeres are typically formed on highly repetitive DNA that is not conserved in sequence or size among organisms and can differ substantially between individuals within the same organism. However, transcription of repetitive DNA has emerged as a highly conserved property of the centromere. Recent work has shown that both the topological effect of transcription on chromatin and the nascent noncoding RNAs contribute to multiple aspects of centromere function. In this review, we discuss the fundamental aspects of centromere transcription, i.e., its dual role in chromatin remodeling/CENP-A deposition and kinetochore assembly during mitosis, from a cell cycle perspective.


Assuntos
Centrômero/genética , Centrômero/metabolismo , Transcrição Gênica , Animais , Aurora Quinase B/metabolismo , Proteína Centromérica A/metabolismo , Montagem e Desmontagem da Cromatina , Segregação de Cromossomos , DNA/genética , DNA/metabolismo , Humanos , Cinetocoros/metabolismo , Mitose , Modelos Genéticos , RNA Polimerase II/metabolismo , RNA Nuclear/genética , RNA Nuclear/metabolismo
17.
Sci Rep ; 8(1): 9268, 2018 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-29915353

RESUMO

Plant tolerance to freezing temperatures is governed by endogenous constitutive components and environmental inducing factors. Nitric oxide (NO) is one of the endogenous components that participate in freezing tolerance regulation. A combined metabolomic and transcriptomic characterization of NO-deficient nia1,2noa1-2 mutant plants suggests that NO acts attenuating the production and accumulation of osmoprotective and regulatory metabolites, such as sugars and polyamines, stress-related hormones, such as ABA and jasmonates, and antioxidants, such as anthocyanins and flavonoids. Accordingly, NO-deficient plants are constitutively more freezing tolerant than wild type plants.


Assuntos
Adaptação Fisiológica , Antocianinas/metabolismo , Arabidopsis/fisiologia , Congelamento , Óxido Nítrico/metabolismo , Osmose , Reguladores de Crescimento de Plantas/metabolismo , Estresse Fisiológico , Ácido Abscísico/biossíntese , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Ciclopentanos/metabolismo , Regulação da Expressão Gênica de Plantas , Glutationa/metabolismo , Glicólise , Metaboloma , Modelos Biológicos , Mutação/genética , Oxilipinas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transcriptoma/genética
18.
Dev Cell ; 42(3): 201-202, 2017 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-28787584

RESUMO

Centromeric transcription is a common eukaryotic centromere feature, yet it is unclear how transcription is linked to underlying repetitive satellite sequences. In this issue of Developmental Cell, McNulty et al. (2017) show for human centromeres that all α-satellite sequences are transcribed into chromatin-bound RNAs and are required for centromere assembly.


Assuntos
Centrômero , Cromatina , DNA Satélite , Humanos , Sequências Repetitivas de Ácido Nucleico
19.
Mol Plant ; 10(6): 791-804, 2017 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-28412546

RESUMO

The process of cold acclimation is an important adaptive response whereby many plants from temperate regions increase their freezing tolerance after being exposed to low non-freezing temperatures. The correct development of this response relies on proper accumulation of a number of transcription factors that regulate expression patterns of cold-responsive genes. Multiple studies have revealed a variety of molecular mechanisms involved in promoting the accumulation of these transcription factors. Interestingly, however, the mechanisms implicated in controlling such accumulation to ensure their adequate levels remain largely unknown. In this work, we demonstrate that prefoldins (PFDs) control the levels of HY5, an Arabidopsis transcription factor with a key role in cold acclimation by activating anthocyanin biosynthesis, in response to low temperature. Our results show that, under cold conditions, PFDs accumulate into the nucleus through a DELLA-dependent mechanism, where they interact with HY5, triggering its ubiquitination and subsequent degradation. The degradation of HY5 would result, in turn, in anthocyanin biosynthesis attenuation, ensuring the accurate development of cold acclimation. These findings uncover an unanticipated nuclear function for PFDs in plant responses to abiotic stresses.


Assuntos
Antocianinas/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Chaperonas Moleculares/metabolismo , Aclimatação , Antocianinas/genética , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Temperatura Baixa , Regulação da Expressão Gênica de Plantas , Chaperonas Moleculares/genética , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Ubiquitinação/fisiologia
20.
Methods Mol Biol ; 1166: 79-89, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24852630

RESUMO

Low temperature is an important determinant in the configuration of natural plant communities and defines the range of distribution and growth of important crops. Some plants, including Arabidopsis, have evolved sophisticated adaptive mechanisms to tolerate low and freezing temperatures. Central to this adaptation is the process of cold acclimation. By means of this process, many plants from temperate regions are able to develop or increase their freezing tolerance in response to low, nonfreezing temperatures. The identification and characterization of factors involved in freezing tolerance are crucial to understand the molecular mechanisms underlying the cold acclimation response and have a potential interest to improve crop tolerance to freezing temperatures. Many genes implicated in cold acclimation have been identified in numerous plant species by using molecular approaches followed by reverse genetic analysis. Remarkably, however, direct genetic analyses have not been conveniently exploited in their capacity for identifying genes with pivotal roles in that adaptive response. In this chapter, we describe a protocol for evaluating the freezing tolerance of both non-acclimated and cold-acclimated Arabidopsis plants. This protocol allows the accurate and simple screening of mutant collections for the identification of novel factors involved in freezing tolerance and cold acclimation.


Assuntos
Aclimatação/genética , Arabidopsis/genética , Arabidopsis/fisiologia , Congelamento , Mutação , DNA Bacteriano/genética , Mutagênese , Fenótipo , Sementes/genética , Sementes/fisiologia , Solo
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