Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling by array of Arabidopsis seedlings mutant for essp3 and brm

ABSTRACT: Synthesis and accumulation of seed storage proteins (SSPs) is an important aspect of the seed maturation program. Genes encoding SSPs are specifically and highly expressed in the seed during maturation. However, the mechanisms that repress the expression of these genes in leaf tissue are not well understood. To gain insight into the repression mechanisms, we have performed a transgenic screening for mutants that express SSPs in leaves. Here we show that mutations of BRAHMA (BRM), a SNF2 chromatin remodelling ATPase, cause the ectopic expression of a subset of SSPs and other embryogenesis related genes in leaf tissue. Consistent with the notion that such SNF2-like ATPases form protein complexes in vivo, we observed similar phenotypes for mutations of AtSWI3C, a BRM interacting partner, and BSH, a SNF5 homolog and essential SWI/SNF subunit. Further, we present chromatin immunoprecipitation evidence that BRM is recruited to the promoters of a number of embryogenesis genes including the 2S genes, which are expressed/elevated in brm leaves. Consistent with its role in nucleosome remodelling, BRM appears to control the chromatin structure of the At2S2 promoter. These results show that a BRM-containing chromatin remodelling ATPase complex is involved in the direct repression of SSPs in leaf tissue. A matrix comprising the signal intensity value of each gene per replicate hybridization and the averaged data of each gene generated from three replicate hybridizations of the wild type and mutant samples, respectively, is linked below as a supplementary file. Experiment Overall Design: Total RNA was isolated from three independent biological replicates of essp3 mutant and Wild type (Pro?CG:GUS)) respectively. Three ATH1 chips were used for the mutant and three for the wild type.

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Mohan babu

PROVIDER: E-GEOD-11505 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

The Arabidopsis BRAHMA chromatin-remodeling ATPase is involved in repression of seed maturation genes in leaves.

Tang Xurong X Hou Anfu A Babu Mohan M Nguyen Vi V Hurtado Lidia L Lu Qing Q Reyes Jose C JC Wang Aiming A Keller Wilfred A WA Harada John J JJ Tsang Edward W T EW Cui Yuhai Y

Plant physiology 20080528 3

Synthesis and accumulation of seed storage proteins (SSPs) is an important aspect of the seed maturation program. Genes encoding SSPs are specifically and highly expressed in the seed during maturation. However, the mechanisms that repress the expression of these genes in leaf tissue are not well understood. To gain insight into the repression mechanisms, we performed a genetic screen for mutants that express SSPs in leaves. Here, we show that mutations affecting BRAHMA (BRM), a SNF2 chromatin-r ...[more]

PMID: 18508955

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Project description:The seed maturation program occurs only during late phase of embryo development and repression of the maturation genes is pivotal for seedling development. However, mechanisms that repress the expression of this program in vegetative tissues are not well understood. A genetic screen was performed for mutants that express maturation genes in leaves. Here, it is shown that mutations affecting SDG8 (SET DOMAIN GROUP 8), a putative histone methyltransferase, cause ectopic expression of a subset of maturation genes in leaves. Further, to investigate the relationship between SDG8 and the Polycomb Group (PcG) proteins, which are known to repress many developmentally important genes including seed maturation genes, double mutants was made and formation of somatic embryos was observed on mutant seedlings with mutations in both SDG8 and EMF2 (EMBRYONIC FLOWER 2). Interestingly, double mutant of sdg8 and mutations in VRN2 (VERNALIZATION 2), a paralog of EMF2, grow and develop normally to maturity. Analysis of histone methylation status at chromatins of a number of maturation loci revealed synergistic effect of emf2 and sdg8 on the deposition of the active histone mark, trimethylation of lysine 4 on histone 3 (H3K4me3), which is consistent with high expression of these genes (formation of somatic embryos) in emf2 sdg8 double mutants. These observations demonstrate a functional cooperative interplay between SDG8 and an EMF2-containing PcG complex in maintaining vegetative cell identity by repressing seed genes to promote seedling development. The work also indicates the functional specificities of PcG complexes in Arabidopsis. Total RNA was isolated from three independent biological replicates of Wild type (ProM-NM-2CG:GUS) and two independent biological replicates of sdg8-2 and essp4/sdg8-5, respectively. Four ATH1 chips were used for the two mutants and three for the wild type. Matrices comprising the signal intensity value of each gene per replicate hybridization and the averaged data of each gene generated from three replicate hybridizations of the wild type and two replicate hybridizations of mutant samples, respectively, are linked below as supplementary files.

Project description:Myocyte enhancer factor 2B (MEF2B) is a transcription factor with somatic mutation hotspots at K4, Y69 and D83 in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). The recurrence of these mutations indicates that they may drive lymphoma development. However, inferring the mechanisms by which they may drive lymphoma development was complicated by our limited understanding of MEF2B’s normal functions. To expand our understanding of the cellular activities of wildtype (WT) and mutant MEF2B, I developed and addressed two hypotheses: (1) identifying genes regulated by WT MEF2B will allow identification of cellular phenotypes affected by MEF2B activity and (2) contrasting the DNA binding sites, effects on gene expression and effects on cellular phenotypes of mutant and WT MEF2B will help refine hypotheses about how MEF2B mutations may contribute to lymphoma development. To address these hypotheses, I first identified genome-wide WT MEF2B binding sites and transcriptome-wide gene expression changes mediated by WT MEF2B. Using these data I identified and validated novel MEF2B target genes. I found that target genes of MEF2B included the cancer genes MYC, TGFB1, CARD11, NDRG1, RHOB, BCL2 and JUN. Identification of target genes led to findings that WT MEF2B promotes expression of mesenchymal markers, promotes HEK293A cell migration, and inhibits DLBCL cell chemotaxis. I then investigated how K4E, Y69H and D83V mutations change MEF2B’s activity. I found that K4E, Y69H and D83V mutations decreased MEF2B DNA binding and decreased MEF2B’s capacity to promote gene expression in both HEK293A and DLBCL cells. These mutations also reduced MEF2B’s capacity to alter HEK293A and DLBCL cell movement. From these data, I hypothesize that MEF2B mutations may promote DLBCL and FL development by reducing expression of MEF2B target genes that would otherwise function to help confine germinal centre B-cells to germinal centres. Overall, my research demonstrates how observations from genome-scale data can be used to identify cellular effects of candidate driver mutations. Moreover, my work provides a unique resource for exploring the role of MEF2B in cell biology: I map for the first time the MEF2B ‘regulome’, demonstrating connections between a relatively understudied transcription factor and genes significant to oncogenesis. We analysed Affymetrix Human Exon 1.0 ST array data from HEK293A cells stably transfected with WT or mutant (K4E, Y69H or D83V) MEF2B-V5 and untransfected control cells. Data was collected in triplicate from all cell types under DMSO treatment, as well as from triplicates of WT and untransfected cells that were ionomycin treated (1.5uM for 6hr).

Dataset Information

Transcription profiling by array of Arabidopsis seedlings mutant for essp3 and brm

Publications

The Arabidopsis BRAHMA chromatin-remodeling ATPase is involved in repression of seed maturation genes in leaves.

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