RESUMO
The Arabidopsis ERECTA family (ERf) of leucine-rich repeat receptor-like kinases (LRR-RLKs) comprising ERECTA (ER), ERECTA-LIKE 1 (ERL1), and ERECTA-LIKE 2 (ERL2) controls epidermal patterning, inflorescence architecture, and stomata development and patterning. These proteins are reported to be plasma membrane associated. Here we show that the er/erl1/erl2 mutant exhibits impaired gibberellin (GA) biosynthesis and perception alongside broad transcriptional changes. The ERf kinase domains were found to localize to the nucleus where they interact with the SWI3B subunit of the SWI/SNF chromatin remodeling complex (CRCs). The er/erl1/erl2 mutant exhibits reduced SWI3B protein level and affected nucleosomal chromatin structure. Similar to swi3c and brm plants with inactivated subunits of SWI/SNF CRCs, it also does not accumulate DELLA RGA and GAI proteins. The ER kinase phosphorylates SWI3B in vitro, and the inactivation of all ERf proteins leads to the decreased phosphorylation of SWI3B protein in vivo. The identified correlation between DELLA overaccumulation and SWI3B proteasomal degradation, and the physical interaction of SWI3B with DELLA proteins indicate an important role of SWI3B-containing SWI/SNF CRCs in gibberellin signaling. Co-localization of ER and SWI3B on GID1 (GIBBERELLIN INSENSITIVE DWARF 1) DELLA target gene promoter regions and abolished SWI3B binding to GID1 promoters in er/erl1/erl2 plants supports the conclusion that ERf-SWI/SNF CRC interaction is important for transcriptional control of GA receptors. Thus, the involvement of ERf proteins in the transcriptional control of gene expression, and observed similar features for human HER2 (epidermal growth family receptor member), indicate an exciting target for further studies of evolutionarily conserved non-canonical functions of eukaryotic membrane receptors.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Humanos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Montagem e Desmontagem da Cromatina , Giberelinas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/genéticaRESUMO
Regulation of ribosomal transcription is under tight control from environmental stimuli, and this control involves changes in the chromatin structure. The underlying mechanism of how chromatin changes in response to nutrient and energy supply in the cell is still unclear. The chromatin-remodeling complex B-WICH is involved in activating the ribosomal transcription, and we show here that knock down of the B-WICH component WSTF results in cells that do not respond to glucose. The promoter is less accessible, and RNA pol I and its transcription factors SL1/TIF-1B and RRN3/TIF-1A, as well as the proto-oncogene c-MYC and the activating deacetylase SIRT7 do not bind upon glucose stimulation. In contrast, the repressive chromatin state that forms after glucose deprivation is reversible, and RNA pol I factors are recruited. WSTF knock down results in an accumulation of the ATPase CHD4, a component of the NuRD chromatin remodeling complex, which is responsible for establishing a repressive poised state at the promoter. The TTF-1, which binds and affect the binding of the chromatin complexes, is important to control the association of activating chromatin component UBF. We suggest that B-WICH is required to allow for a shift to an active chromatin state upon environmental stimulation, by counteracting the repressive state induced by the NuRD complex.
Assuntos
Montagem e Desmontagem da Cromatina/genética , Cromatina/genética , Glucose/genética , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/genética , Ribossomos/genética , Transcrição Gênica/genética , Adenosina Trifosfatases/genética , Linhagem Celular , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Células HEK293 , Células HeLa , Humanos , Proteínas Nucleares/genética , Proteínas Pol1 do Complexo de Iniciação de Transcrição/genética , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas c-myc/genética , RNA Polimerase I/genética , Sirtuínas/genética , Fatores de Transcrição/genéticaRESUMO
SWI/SNF complexes associate with genes and regulate transcription by altering the chromatin at the promoter. It has recently been shown that these complexes play a role in pre-mRNA processing by associating at alternative splice sites. Here, we show that SWI/SNF complexes are involved also in pre-mRNA 3' end maturation by facilitating 3' end cleavage of specific pre-mRNAs. Comparative proteomics show that SWI/SNF ATPases interact physically with subunits of the cleavage and polyadenylation complexes in fly and human cells. In Drosophila melanogaster, the SWI/SNF ATPase Brahma (dBRM) interacts with the CPSF6 subunit of cleavage factor I. We have investigated the function of dBRM in 3' end formation in S2 cells by RNA interference, single-gene analysis and RNA sequencing. Our data show that dBRM facilitates pre-mRNA cleavage in two different ways: by promoting the association of CPSF6 to the cleavage region and by stabilizing positioned nucleosomes downstream of the cleavage site. These findings show that SWI/SNF complexes play a role also in the cleavage of specific pre-mRNAs in animal cells.
Assuntos
Regiões 3' não Traduzidas/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Processamento de Terminações 3' de RNA , Ribonucleoproteína Nuclear Pequena U1/genética , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Células HeLa , Humanos , Ribonucleoproteína Nuclear Pequena U1/metabolismo , Transativadores/genética , Transativadores/metabolismoRESUMO
SWI/SNF ATP-dependent chromatin remodeling complexes (CRCs) play important roles in the regulation of transcription, cell cycle, DNA replication, repair, and hormone signaling in eukaryotes. The core of SWI/SNF CRCs composed of a SWI2/SNF2 type ATPase, a SNF5 and two of SWI3 subunits is sufficient for execution of nucleosome remodeling in vitro. The Arabidopsis genome encodes four SWI2/SNF2 ATPases, four SWI3, a single SNF5 and two SWP73 subunits. Genes of the core SWI/SNF components have critical but not fully overlapping roles during plant growth, embryogenesis, and sporophyte development. Here we show that the Arabidopsis swi3c mutant exhibits a phenotypic reversion when grown at lower temperature resulting in partial restoration of its embryo, root development and fertility defects. Our data indicates that the swi3c mutation alters the expression of several genes engaged in low temperature responses. The location of SWI3C-containing SWI/SNF CRCs on the ICE1, MYB15 and CBF1 target genes depends on the temperature conditions, and the swi3c mutation thus also influences the transcription of several cold-responsive (COR) genes. These findings, together with genetic analysis of swi3c/ice1 double mutant and enhanced freezing tolerance of swi3c plants illustrate that SWI/SNF CRCs contribute to fine-tuning of plant growth responses to different temperature regimes.
Assuntos
Trifosfato de Adenosina/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Montagem e Desmontagem da Cromatina/genética , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Regiões 5' não Traduzidas , Adaptação Fisiológica/genética , Arabidopsis/genética , Cromatina/metabolismo , Imunoprecipitação da Cromatina , Temperatura Baixa , Regulação da Expressão Gênica de Plantas/genética , Mutação , Nucleossomos/genética , Fenótipo , Plantas Geneticamente Modificadas , Transativadores/genética , Transativadores/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Arabidopsis thaliana SWP73A and SWP73B are homologs of mammalian BRAHMA-associated factors (BAF60s) that tether SWITCH/SUCROSE NONFERMENTING chromatin remodeling complexes to transcription factors of genes regulating various cell differentiation pathways. Here, we show that Arabidopsis thaliana SWP73s modulate several important developmental pathways. While undergoing normal vegetative development, swp73a mutants display reduced expression of FLOWERING LOCUS C and early flowering in short days. By contrast, swp73b mutants are characterized by retarded growth, severe defects in leaf and flower development, delayed flowering, and male sterility. MNase-Seq, transcript profiling, and ChIP-Seq studies demonstrate that SWP73B binds the promoters of ASYMMETRIC LEAVES1 and 2, KANADI1 and 3, and YABBY2, 3, and 5 genes, which regulate leaf development and show coordinately altered transcription in swp73b plants. Lack of SWP73B alters the expression patterns of APETALA1, APETALA3, and the MADS box gene AGL24, whereas other floral organ identity genes show reduced expression correlating with defects in flower development. Consistently, SWP73B binds to the promoter regions of APETALA1 and 3, SEPALLATA3, LEAFY, UNUSUAL FLORAL ORGANS, TERMINAL FLOWER1, AGAMOUS-LIKE24, and SUPPRESSOR OF CONSTANS OVEREXPRESSION1 genes, and the swp73b mutation alters nucleosome occupancy on most of these loci. In conclusion, SWP73B acts as important modulator of major developmental pathways, while SWP73A functions in flowering time control.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Flores/crescimento & desenvolvimento , Flores/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Subunidades Proteicas/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/embriologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Imunoprecipitação da Cromatina , Flores/genética , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Nuclease do Micrococo/metabolismo , Mutagênese Insercional/genética , Mutação/genética , Nucleossomos/metabolismo , Folhas de Planta/genética , Regiões Promotoras Genéticas/genética , Ligação Proteica , Subunidades Proteicas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Técnicas do Sistema de Duplo-HíbridoRESUMO
Switch (SWI)/Sucrose Nonfermenting (SNF)-type chromatin-remodeling complexes (CRCs) are involved in regulation of transcription, DNA replication and repair, and cell cycle. Mutations of conserved subunits of plant CRCs severely impair growth and development; however, the underlying causes of these phenotypes are largely unknown. Here, we show that inactivation of SWI3C, the core component of Arabidopsis (Arabidopsis thaliana) SWI/SNF CRCs, interferes with normal functioning of several plant hormone pathways and alters transcriptional regulation of key genes of gibberellin (GA) biosynthesis. The resulting reduction of GA4 causes severe inhibition of hypocotyl and root elongation, which can be rescued by exogenous GA treatment. In addition, the swi3c mutation inhibits DELLA-dependent transcriptional activation of GIBBERELLIN-INSENSITIVE DWARF1 (GID1) GA receptor genes. Down-regulation of GID1a in parallel with the DELLA repressor gene REPRESSOR OF GA1-3 1 in swi3c indicates that lack of SWI3C also leads to defects in GA signaling. Together with the recent demonstration of function of SWI/SNF ATPase BRAHMA in the GA pathway, these results reveal a critical role of SWI/SNF CRC in the regulation of GA biosynthesis and signaling. Moreover, we demonstrate that SWI3C is capable of in vitro binding to, and shows in vivo bimolecular fluorescence complementation interaction in cell nuclei with, the DELLA proteins RGA-LIKE2 and RGA-LIKE3, which affect transcriptional activation of GID1 and GA3ox (GIBBERELLIN 3-OXIDASE) genes controlling GA perception and biosynthesis, respectively. Furthermore, we show that SWI3C also interacts with the O-GlcNAc (O-linked N-acetylglucosamine) transferase SPINDLY required for proper functioning of DELLAs and acts hypostatically to (SPINDLY) in the GA response pathway. These findings suggest that DELLA-mediated effects in GA signaling as well as their role as a hub in hormonal cross talk may be, at least in part, dependent on their direct physical interaction with complexes responsible for modulation of chromatin structure.
Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/efeitos dos fármacos , Proteínas Cromossômicas não Histona/fisiologia , Giberelinas/farmacologia , Reguladores de Crescimento de Plantas/farmacologia , Transdução de Sinais/genética , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/metabolismo , Montagem e Desmontagem da Cromatina , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Regulação da Expressão Gênica de PlantasRESUMO
The Fulani ethnic group has relatively better protection from Plasmodium falciparum malaria, as reflected by fewer symptomatic cases of malaria, lower infection rates, and lower parasite densities compared to sympatric ethnic groups. However, the basis for this lower susceptibility to malaria by the Fulani is unknown. The incidence of classic malaria resistance genes are lower in the Fulani than in other sympatric ethnic populations, and targeted SNP analyses of other candidate genes involved in the immune response to malaria have not been able to account for the observed difference in the Fulani susceptibility to P.falciparum. Therefore, we have performed a pilot study to examine global transcription and DNA methylation patterns in specific immune cell populations in the Fulani to elucidate the mechanisms that confer the lower susceptibility to P.falciparum malaria. When we compared uninfected and infected Fulani individuals, in contrast to uninfected and infected individuals from the sympatric ethnic group Mossi, we observed a key difference: a strong transcriptional response was only detected in the monocyte fraction of the Fulani, where over 1000 genes were significantly differentially expressed upon P.falciparum infection.
Assuntos
Resistência à Doença , Etnicidade , Malária Falciparum/genética , Monócitos/imunologia , Transcrição Gênica , Células Cultivadas , Metilação de DNA , Perfilação da Expressão Gênica , Humanos , Projetos PilotoRESUMO
SWI/SNF chromatin remodeling complexes perform a pivotal function in the regulation of eukaryotic gene expression. Arabidopsis (Arabidopsis thaliana) mutants in major SWI/SNF subunits display embryo-lethal or dwarf phenotypes, indicating their critical role in molecular pathways controlling development and growth. As gibberellins (GA) are major positive regulators of plant growth, we wanted to establish whether there is a link between SWI/SNF and GA signaling in Arabidopsis. This study revealed that in brm-1 plants, depleted in SWI/SNF BRAHMA (BRM) ATPase, a number of GA-related phenotypic traits are GA-sensitive and that the loss of BRM results in markedly decreased level of endogenous bioactive GA. Transcriptional profiling of brm-1 and the GA biosynthesis mutant ga1-3, as well as the ga1-3/brm-1 double mutant demonstrated that BRM affects the expression of a large set of GA-responsive genes including genes responsible for GA biosynthesis and signaling. Furthermore, we found that BRM acts as an activator and directly associates with promoters of GA3ox1, a GA biosynthetic gene, and SCL3, implicated in positive regulation of the GA pathway. Many GA-responsive gene expression alterations in the brm-1 mutant are likely due to depleted levels of active GAs. However, the analysis of genetic interactions between BRM and the DELLA GA pathway repressors, revealed that BRM also acts on GA-responsive genes independently of its effect on GA level. Given the central position occupied by SWI/SNF complexes within regulatory networks controlling fundamental biological processes, the identification of diverse functional intersections of BRM with GA-dependent processes in this study suggests a role for SWI/SNF in facilitating crosstalk between GA-mediated regulation and other cellular pathways.