Project description:Abscisic acid (ABA) is an essential hormone that allows plants to respond to environmental stresses such as high salinity, drought and cold. It also plays a pivotal role in seed maturation and germination. Because of its importance, transcriptome changes in response to ABA have been profiled extensively by the plant community. Very few ChIP-chip/seq of ABA-related TFs have been reported to date. To fill the knowledge gap about how ABA works at the transcriptional level, we carried out ChIP-seq on 21 TFs from 11 different families using both mock- and ABA-treated conditions. Analyses of the resulting 122 ChIP-seq datasets identified 326,698 TF binding events using a stringent statistical cutoff. Based on our data, a comprehensive regulatory network in Arabidopsis thaliana was constructed. We uncovered determinants of dynamic TF binding and defined a hierarchy among TFs to explain differential gene expression and pathway feedback regulation. By extrapolating regulatory characteristics observed for the canonical ABA pathway components, we identified a new family of transcriptional regulators modulating ABA and salt responsiveness, and demonstrate their utility to modulate plant resilience to osmotic stress.
Project description:Abscisic acid (ABA) is an essential hormone that allows plants to respond to environmental stresses such as high salinity, drought and cold. It also plays a pivotal role in seed maturation and germination. Because of its importance, transcriptome changes in response to ABA have been profiled extensively by the plant community. Very few ChIP-chip/seq of ABA-related TFs have been reported to date. To fill the knowledge gap about how ABA works at the transcriptional level, we carried out ChIP-seq on 21 TFs from 11 different families using both mock- and ABA-treated conditions. Analyses of the resulting 122 ChIP-seq datasets identified 326,698 TF binding events using a stringent statistical cutoff. Based on our data, a comprehensive regulatory network in Arabidopsis thaliana was constructed. We uncovered determinants of dynamic TF binding and defined a hierarchy among TFs to explain differential gene expression and pathway feedback regulation. By extrapolating regulatory characteristics observed for the canonical ABA pathway components, we identified a new family of transcriptional regulators modulating ABA and salt responsiveness, and demonstrate their utility to modulate plant resilience to osmotic stress.
Project description:Abscisic acid (ABA) is an essential hormone that allows plants to respond to environmental stresses such as high salinity, drought and cold. It also plays a pivotal role in seed maturation and germination. Because of its importance, transcriptome changes in response to ABA have been profiled extensively by the plant community. Very few ChIP-chip/seq of ABA-related TFs have been reported to date. To fill the knowledge gap about how ABA works at the transcriptional level, we carried out ChIP-seq on 21 TFs from 11 different families using both mock- and ABA-treated conditions. Analyses of the resulting 122 ChIP-seq datasets identified 326,698 TF binding events using a stringent statistical cutoff. Based on our data, a comprehensive regulatory network in Arabidopsis thaliana was constructed. We uncovered determinants of dynamic TF binding and defined a hierarchy among TFs to explain differential gene expression and pathway feedback regulation. By extrapolating regulatory characteristics observed for the canonical ABA pathway components, we identified a new family of transcriptional regulators modulating ABA and salt responsiveness, and demonstrate their utility to modulate plant resilience to osmotic stress.
Project description:Abscisic acid (ABA) is an essential hormone that allows plants to respond to environmental stresses such as high salinity, drought and cold. It also plays a pivotal role in seed maturation and germination. Because of its importance, transcriptome changes in response to ABA have been profiled extensively by the plant community. Very few ChIP-chip/seq of ABA-related TFs have been reported to date. To fill the knowledge gap about how ABA works at the transcriptional level, we carried out ChIP-seq on 21 TFs from 11 different families using both mock- and ABA-treated conditions. Analyses of the resulting 122 ChIP-seq datasets identified 326,698 TF binding events using a stringent statistical cutoff. Based on our data, a comprehensive regulatory network in Arabidopsis thaliana was constructed. We uncovered determinants of dynamic TF binding and defined a hierarchy among TFs to explain differential gene expression and pathway feedback regulation. By extrapolating regulatory characteristics observed for the canonical ABA pathway components, we identified a new family of transcriptional regulators modulating ABA and salt responsiveness, and demonstrate their utility to modulate plant resilience to osmotic stress.
Project description:Chromatin immunoprecipitation followed by massively parallel DNA sequencing (ChIP-seq) or microarray hybridization (ChIP-chip) has been widely used to determine the genomic occupation of transcription factors (TFs). We have previously developed a probabilistic method, called TIP (Target Identification from Profiles), to identify TF target genes using ChIP-seq/ChIP-chip data. To achieve high specificity, TIP applies a conservative method to estimate significance of target genes, with the trade-off being a relatively low sensitivity of target gene identification compared to other methods. Additionally, TIP's output does not render binding-peak locations or intensity, information highly useful for visualization and general experimental biological use, while the variability of ChIP-seq/ChIP-chip file formats has made input into TIP more difficult than desired.To improve upon these facets, here we present are fined TIP with key extensions. First, it implements a Gaussian mixture model for p-value estimation, increasing target gene identification sensitivity and more accurately capturing the shape of TF binding profile distributions. Second, it enables the incorporation of TF binding-peak data by identifying their locations in significant target gene promoter regions and quantifies their strengths. Finally, for full ease of implementation we have incorporated it into a web server ( http://syslab3.nchu.edu.tw/iTAR/ ) that enables flexibility of input file format, can be used across multiple species and genome assembly versions, and is freely available for public use. The web server additionally performs GO enrichment analysis for the identified target genes to reveal the potential function of the corresponding TF.The iTAR web server provides a user-friendly interface and supports target gene identification in seven species, ranging from yeast to human. To facilitate investigating the quality of ChIP-seq/ChIP-chip data, the web server generates the chart of the characteristic binding profiles and the density plot of normalized regulatory scores. The iTAR web server is a useful tool in identifying TF target genes from ChIP-seq/ChIP-chip data and discovering biological insights.
Project description:Chromatin immunoprecipitation followed by sequencing (ChIP-seq) is widely used to map histone marks and transcription factor binding throughout the genome. Here we present ChIPmentation, a method that combines chromatin immunoprecipitation with sequencing library preparation by Tn5 transposase ('tagmentation'). ChIPmentation introduces sequencing-compatible adaptors in a single-step reaction directly on bead-bound chromatin, which reduces time, cost and input requirements, thus providing a convenient and broadly useful alternative to existing ChIP-seq protocols.