Unknown,Transcriptomics,Genomics,Proteomics

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RNA-seq analysis of Col-0 and nrf1-2 mutant under Fe sufficient and Fe deficiency condition

ABSTRACT: This study will reveal the importance nrf1-2 in controlling the Fe homeostasis network under iron deficiency

INSTRUMENT(S): Illumina HiSeq 4000, Windows 7

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Dr. Ming-Jung Liu

PROVIDER: E-MTAB-8157 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Cell-type specific transcriptional profiles were generated by FACS (Fluorescence Activated Cell Sorting) sorting of roots that express cell-type specific GFP-reporters. Five different GFP-reporter lines were utilized allowing us to obtain transcriptional profiles for cells in all radial zones of the root. FACS cell populations were isolated from roots grown under standard conditions or roots that had been transfered to -Fe media for 24 hours. Little is known about how developmental cues affect the way cells interpret their environment. Here we characterize the transcriptional response of different cell layers and developmental stages of the Arabidopsis root to high salinity and find that transcriptional responses are highly constrained by developmental parameters. These transcriptional changes lead to the differential regulation of specific biological functions in subsets of cell-layers, several of which correspond to observable physiological changes. We show that known stress pathways primarily control semi-ubiquitous responses and use mutants that disrupt epidermal patterning to reveal cell-layer specific and inter-cell-layer effects. By performing a similar analysis using iron-deprivation we identify common cell-type specific stress responses and environment-independent biological functions that define each cell type. Experiment Overall Design: To gain a genome-scale understanding of the role that developmental processes play in regulating stimulus response, we examined the effect of -Fe stress on gene expression along the radial axis of the root. Cell identity is the main variable that changes along the radial axis with the epidermis representing the outermost tissue layer and the stele representing the inner most layer. 5 different GFP reporter lines were used to isolate specific populations of cells from the Arabidopsis root using FACS sorting of protoplasted cells. GFP-reporter lines were exposed to iron deficient (-Fe) conditions (0.3mM Ferrozine in MS media containing no ferrous sulfate) for 24 hours before hand.

Project description:To gain a genome-scale understanding of the role that developmental processes play in regulating stimulus response, we examined the effect of -Fe stress on gene expression along the longitudinal axis of the root. Since roots grow from stem cells located near the tip, the position of cells along the longitudinal axis can be used as a proxy for developmental time, with distance from the root tip correlating with increased differentiation. To estimate the role developmental stage plays in regulating salt response, roots were dissected into four longitudinal zones (LZ data set) after transfer to standard or -Fe media and transcriptionally profiled. Little is known about how developmental cues affect the way cells interpret their environment. Here we characterize the transcriptional response of different cell layers and developmental stages of the Arabidopsis root to high salinity and find that transcriptional responses are highly constrained by developmental parameters. These transcriptional changes lead to the differential regulation of specific biological functions in subsets of cell-layers, several of which correspond to observable physiological changes. We show that known stress pathways primarily control semi-ubiquitous responses and use mutants that disrupt epidermal patterning to reveal cell-layer specific and inter-cell-layer effects. By performing a similar analysis using iron-deprivation we identify common cell-type specific stress responses and environment-independent biological functions that define each cell type. Experiment Overall Design: Roots were grown under standard conditions for 5 days then transfered to standard media or iron deficient (-Fe) conditions (0.3mM Ferrozine in MS media containing no ferrous sulfate). 24 hours after transferring seedlings, roots were cut into 4 regions using a razor blade. The first cut was made ~150 Âµm from the root tip at the point where the shape of the root transitions from conical to cylindrical (Zone 1). The second cut was made ~200 Âµm above the first cut, at the point were the root becomes less optically dense, which marks the approximate end of the meristematic zone (Zone 2). The third cut was made ~200-300 Âµm above the second cut, just below the region where root hairs begin to emerge (Zone 3). The fourth cut was made ~1 mm above the third cut (Zone 4).

Project description:Transcriptional profile of whole roots of wild-type and pye-1 mutants exposed to 24 hours -Fe were generated Global population increases and climate change underscore the need for better comprehension of how plants acquire and process nutrients such as iron. A systems biology approach was taken to elucidate novel regulatory mechanisms involved in plant responses to iron deficiency (-Fe). Using cell-type specific transcriptional profiling we identified a pericycle-specific iron deficiency response, and a previously uncharacterized transcription factor, POPEYE (PYE), that plays an important role in this response. Functional analysis of PYE suggests that it positively regulates growth and development under iron deficient conditions. ChIP-on-chip analysis and transcriptional profiling reveal that PYE helps maintain iron homeostasis by directly and indirectly regulating the expression of ferric reductases, metal ion transporters, iron storage proteins, and other key iron homeostasis genes. In addition to PYE, we also identified a second protein BRUTUS (BTS), which appears to negatively regulate the response to iron deficiency. BTS is a unique putative E3 ligase protein, with metal ion binding and DNA binding domains. PYE and BTS are tightly co-regulated and physically interact with PYE paralogs, one of which is thought to positively regulate expression of genes involved in iron homeostasis. We propose that iron content is sensed within the pericycle where PYE, perhaps in conjunction with BTS and other regulatory proteins, is then activated to control a regulatory network involved in maintaining proper iron distribution in plants. Keywords: Expression analysis To determine how loss of PYE expression affects the transcriptional profile of whole roots, pye-1 mutants and wild-type seeds were germinated under standard growth conditions then transferred to standard media (control, MS media) or iron deficient media (-Fe, 0.3mM Ferrozine in MS media containing no ferrous sulfate). After 24 hours of exposure to +Fe or -Fe whole roots were collected and analyzed.

Project description:Eukaryotic transcription factors (TFs) are key determinants of gene activity, yet they bind only a fraction of their corresponding DNA sequence motifs in any given cell type. Chromatin has the potential to restrict accessibility of binding sites; however, in which context chromatin states are instructive for TF binding remains mainly unknown. To explore the contribution of DNA methylation to constrained TF binding, we mapped DNase-I-hypersensitive sites in murine stem cells in the presence and absence of DNA methylation. Methylation-restricted sites are enriched for TF motifs containing CpGs, especially for those of NRF1. In fact, the TF NRF1 occupies several thousand additional sites in the unmethylated genome, resulting in increased transcription. Restoring de novo methyltransferase activity initiates remethylation at these sites and outcompetes NRF1 binding. This suggests that binding of DNA-methylationsensitive TFs relies on additional determinants to induce local hypomethylation. In support of this model, removal of neighbouring motifs in cis or of a TF in trans causes local hypermethylation and subsequent loss of NRF1 binding. This competition between DNA methylation and TFs in vivo reveals a case of cooperativity between TFs that acts indirectly via DNA methylation. Methylation removal by methylation-insensitive factors enables occupancy of methylation-sensitive factors, a principle that rationalizes hypomethylation of regulatory regions. DNase-seq (2 replicates) in mouse embryonic stem cells with (WT) and without DNA methylation (DNMT TKO). RNA-seq (3 replicates) in WT and DNMT TKO cells and in DNMT TKO cells after treatment with control siRNA or siRNA targeting Nrf1. H3K27ac ChIP-seq (2 replicates) in WT and DNMT TKO cells. NRF1 ChIP-seq (2 replicates) in WT and DNMT TKO cells, in WT upon culture in different conditions (adaptation to 2i and back to serum), upon transient overexpression of NRF1 and after differentiation into neuronal progenitor cells (NP). Whole-genome bisulfite sequencing in DNMT TKO cells and in WT upon culture in different conditions (adaptation to 2i and back to serum). NRF1 ChIP-seq (2 replicates) in human HMEC and HCC1954 cells.

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RNA-seq analysis of Col-0 and nrf1-2 mutant under Fe sufficient and Fe deficiency condition

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