Project description:LHY and CCA1 encode single MYB transcription factors, involved in circadian clock. However, direct target genes of LHY and CCA1 in a genomic scale were largely unknown. To reveal bound genes by CCA1, chimeric protein CCA1-FLAG was expressed under CCA1 promoter in cca1 lhy (CCA1pro:CCA1-FLAG/ cca1 lhy). ChIP was performed using anti-FLAG antibody (F3165; SIGMA), which was bound to Dynabeads Protein G (100-03D; Life Technologies), and ChIP DNA were analyzed by IonPGM or Illumina GAII. Chromatin immunoprecipitation was performed for CCA1-FLAG-expressing Arabidopsis. ChIP DNA was analyzed 2 types of deep sequencers (Illumina GAII and IonPGM).
Project description:LHY and CCA1 encode single MYB transcription factors, involved in circadian clock. However, direct target genes of LHY and CCA1 in a genomic scale were largely unknown. To reveal bound genes by CCA1, chimeric protein CCA1-FLAG was expressed under CCA1 promoter in cca1 lhy (CCA1pro:CCA1-FLAG/ cca1 lhy). ChIP was performed using anti-FLAG antibody (F3165; SIGMA), which was bound to Dynabeads Protein G (100-03D; Life Technologies), and ChIP DNA were analyzed by IonPGM or Illumina GAII.
Project description:H3K27me3 is a histone modification associated with transcriptional repression that plays a pivotal role in differentiation and development in plants and animals. H2A.Z, a histone variant of H2A, is often colocalized with H3K27me3 in Arabidopsis. Previous genome-wide studies have raised the possibility that H2A.Z contributes to H3K27me3 homeostasis in plants. To examine the contribution of H2A.Z to H3K27me3, we utilized hta9 hta11, a plant line which is defective in two of three genes that code for H2A.Z and has been previously characterized as an H2A.Z-depletion mutant. Surprisingly, ChIP-seq analysis of H2A.Z enrichment revealed that hta9 hta11 plants exhibit a nearly indistinguishable genic H2A.Z enrichment pattern relative to wild type with few genes that are enriched or depleted for H2A.Z. Mass spectrometry measurement of histone protein abundance in hta9 hta11 plants in conjunction with our ChIP-seq analysis indicates that the chromatin of hta9 hta11 plants exhibits altered relative abundance of H2A.Z variants rather than a global depletion of H2A.Z. In contrast, ChIP-seq analysis of H3K27me3 reveals that hta9 hta11 plants exhibit a robust global reduction in H3K27me3 enrichment, and numerous genes are identified that exhibit altered levels for H3K27me3. In addition, hta9 hta11 plants exhibit differential expression of thermoresponsive genes that have previously been shown to be dependent on H2A.Z. Our combined analyses indicate that specific H2A.Z isoforms play distinct roles in chromatin composition and gene expression in Arabidopsis, particularly with regards to H3K27me3 homeostasis.
Project description:The plant circadian clock exerts a critical role in the regulation of multiple biological processes including responses to biotic and abiotic stresses. It is estimated that the clock regulates up to 80% of the transcriptome in Arabidopsis, thus understanding the molecular mechanisms that control this rhythmic transcriptome requires identification of the targets of each clock component. The Arabidopsis core clock is partially comprised of a transcriptional regulatory loop between the MYB domain containing transcription factors CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), and TIMING OF CAB EXPRESSION1 (TOC1). As a key component of the clock, CCA1 is able to initiate and set the phase of clock-controlled rhythms. CCA1 regulates the transcription of several genes by directly binding to the evening element (EE) motif primarily found in the promoters of evening expressed genes. Using a genome-wide approach we have identified direct targets of CCA1 in plants grown in constant (LL) and driven conditions (LD). These CCA1 targets are enriched for a myriad of biological processes and stress responses. While many of these target genes are evening phased and contain the EE in their promoter regions, a significant subset is morning phased and lack an EE. Furthermore, several CCA1 targets do not cycle in either LL or LD or both. Expression analysis in CCA1 overexpressing plants confirms CCA1 regulation of analyzed targets. Our results emphasize an expanded role for the circadian clock in regulation of key pathways in Arabidopsis, and provide a comprehensive and solid resource for future functional studies. ChIP-Seq of CCA1-GFP plants under control of the CCA1 promoter in continuous light and diel conditions
Project description:H3K27me3 is a histone modification associated with transcriptional repression that plays a pivotal role in differentiation and development in plants and animals. H2A.Z, a histone variant of H2A, is often colocalized with H3K27me3 in Arabidopsis. Previous genome-wide studies have raised the possibility that H2A.Z contributes to H3K27me3 homeostasis in plants. To examine the contribution of H2A.Z to H3K27me3, we utilized hta9 hta11, a plant line which is defective in two of three genes that code for H2A.Z and has been previously characterized as an H2A.Z-depletion mutant. Surprisingly, ChIP-seq analysis of H2A.Z enrichment revealed that hta9 hta11 plants exhibit a nearly indistinguishable genic H2A.Z enrichment pattern relative to wild type with few genes that are enriched or depleted for H2A.Z. Mass spectrometry measurement of histone protein abundance in hta9 hta11 plants in conjunction with our ChIP-seq analysis indicates that the chromatin of hta9 hta11 plants exhibits altered relative abundance of H2A.Z variants rather than a global depletion of H2A.Z. In contrast, ChIP-seq analysis of H3K27me3 reveals that hta9 hta11 plants exhibit a robust global reduction in H3K27me3 enrichment, and numerous genes are identified that exhibit altered levels for H3K27me3. In addition, hta9 hta11 plants exhibit differential expression of thermoresponsive genes that have previously been shown to be dependent on H2A.Z. Our combined analyses indicate that specific H2A.Z isoforms play distinct roles in chromatin composition and gene expression in Arabidopsis, particularly with regards to H3K27me3 homeostasis.
Project description:The plant circadian clock exerts a critical role in the regulation of multiple biological processes including responses to biotic and abiotic stresses. It is estimated that the clock regulates up to 80% of the transcriptome in Arabidopsis, thus understanding the molecular mechanisms that control this rhythmic transcriptome requires identification of the targets of each clock component. The Arabidopsis core clock is partially comprised of a transcriptional regulatory loop between the MYB domain containing transcription factors CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), and TIMING OF CAB EXPRESSION1 (TOC1). As a key component of the clock, CCA1 is able to initiate and set the phase of clock-controlled rhythms. CCA1 regulates the transcription of several genes by directly binding to the evening element (EE) motif primarily found in the promoters of evening expressed genes. Using a genome-wide approach we have identified direct targets of CCA1 in plants grown in constant (LL) and driven conditions (LD). These CCA1 targets are enriched for a myriad of biological processes and stress responses. While many of these target genes are evening phased and contain the EE in their promoter regions, a significant subset is morning phased and lack an EE. Furthermore, several CCA1 targets do not cycle in either LL or LD or both. Expression analysis in CCA1 overexpressing plants confirms CCA1 regulation of analyzed targets. Our results emphasize an expanded role for the circadian clock in regulation of key pathways in Arabidopsis, and provide a comprehensive and solid resource for future functional studies.