Urquiza2021 - Arabidopsis circadian clock, absolute RNA units
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ABSTRACT:
SUBMITTER: 
Andrew J Millar
PROVIDER: MODEL2212200001 | BioModels | 2022-12-21
REPOSITORIES: BioModels
Dataset's files
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| MODEL2212200001?filename=U2019.3.xml | Xml |
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Project description:Model U2020.3.
This model of the clock gene circuit in the plant Arabidopsis thaliana is inspired by the P2011 model, published in Pokhilko et al Mol Syst Biol 2012. The U2019 version uses very similar interactions to P2011, where the combined LHY/CCA1 component indirectly activates the wave of PRR gene expression, whereas the U2020 version uses both indirect activation and inter-PRR repression. The .3 versions of each model are scaled to match the absolute RNA level data from the TiMet project, in Flis et al. 2015.
SBML files were verified using COPASI 4.24 (Build 197) software. The full process is described in Urquiza and Millar, In Silico Plants, 2021.
2022-12-21 | MODEL2212200002 | BioModels
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.
2016-03-11 | GSE67903 | GEO
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).
2016-03-11 | E-GEOD-67903 | biostudies-arrayexpress
Project description:The first described feedback loop of the Arabidopsis circadian clock is based on reciprocal regulation between TOC1 and CCA1/LHY. CCA1 and LHY are MYB transcription factors that bind directly to the TOC1 promoter to negatively regulate its expression. Conversely, the activity of TOC1 has remained less well characterized. Genetic data supports that TOC1 is necessary for the reactivation of CCA1/LHY, but there is little description of its biochemical function. Here we show that TOC1 occupies specific genomic regions in the CCA1 and LHY promoters. Purified TOC1 binds directly to DNA through its CCT domain, which is similar to known DNA binding domains. Chemical induction and transient overexpression of TOC1 in Arabidopsis seedlings cause repression of CCA1/LHY expression demonstrating that TOC1 can repress direct targets, and mutation or deletion of the CCT domain prevents this repression showing that DNA binding is necessary for TOC1 action. Furthermore, we use the Gal4/UAS system in Arabidopsis to show that TOC1 acts as a general transcriptional repressor, and that repression activity is in the Pseudoreceiver (PR) domain of the protein. To identify the genes regulated by TOC1 on a genomic scale, we couple TOC1 chemical induction with microarray analysis and identify new potential TOC1 targets and output pathways. Together these results define the biochemical action of the core clock protein TOC1 and refine our perspective on how plant clocks function. Keywords: Expression profiling by array
2012-01-15 | GSE34897 | GEO
Project description:The first described feedback loop of the Arabidopsis circadian clock is based on reciprocal regulation between TOC1 and CCA1/LHY. CCA1 and LHY are MYB transcription factors that bind directly to the TOC1 promoter to negatively regulate its expression. Conversely, the activity of TOC1 has remained less well characterized. Genetic data supports that TOC1 is necessary for the reactivation of CCA1/LHY, but there is little description of its biochemical function. Here we show that TOC1 occupies specific genomic regions in the CCA1 and LHY promoters. Purified TOC1 binds directly to DNA through its CCT domain, which is similar to known DNA binding domains. Chemical induction and transient overexpression of TOC1 in Arabidopsis seedlings cause repression of CCA1/LHY expression demonstrating that TOC1 can repress direct targets, and mutation or deletion of the CCT domain prevents this repression showing that DNA binding is necessary for TOC1 action. Furthermore, we use the Gal4/UAS system in Arabidopsis to show that TOC1 acts as a general transcriptional repressor, and that repression activity is in the Pseudoreceiver (PR) domain of the protein. To identify the genes regulated by TOC1 on a genomic scale, we couple TOC1 chemical induction with microarray analysis and identify new potential TOC1 targets and output pathways. Together these results define the biochemical action of the core clock protein TOC1 and refine our perspective on how plant clocks function. Keywords: Expression profiling by array wild type (Col-0) and ALC::TOC1 were sown on Murashige-Skoog with 0.8% agar, stratified for 48 hours and grown in12:12 light:dark (LD) for 12 days and either left in LD or transferred to constant light (LL) and then grown for one more day before the start of the experiment. Tissue was submerged in Murashige-Skoog media supplemented with 2.5% ethanol or no ethanol (mock) and with 20mM MG132 for 3 hours and harvested at ZT1. Three replicates each of the seedlings were collected and frozen in liquid nitrogen.
2012-01-15 | E-GEOD-34897 | biostudies-arrayexpress
Project description:Genome-wide gene expression profile of Arabidopsis thaliana cca1 lhy double mutant.
| PRJDB3468 | ENA
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.
2015-07-26 | GSE70533 | GEO
Project description:Transcriptome analysis has revealed a light-regulated WD (tryptophan and aspartate)-containing protein, LWD1. LWD1 and LWD2 share greater than 90% amino acid sequence homology. The lack of phenotype changes in the lwd1 or lwd2 single mutant implies that the proteins function redundantly. The lwd1lwd2 double mutant, however, has an early flowering phenotype under both long-day (LD) and short-day (SD) conditions. Functional complementation experiment revealed that LWDs are indeed responsible for the defect in photoperiod sensing in lwd1lwd2 double mutant plants. The expression of LWD1 exhibits a diurnal pattern and peaks before dawn. The period length of oscillator (CCA1, LHY, TOC1 and ELF4) and output (CCR2 and CAB2) genes in the lwd1lwd2 double mutant is significantly shorter than that in wild-type Arabidopsis under free running condition. Under entrainment conditions, the expression phase of oscillator (CCA1, LHY, TOC1 and ELF4) and output (GI, FKF1, CDF1, CO and FT) genes shifts ~3 hr forward in the lwd1lwd2 double mutant. Our data indicated that the early flowering phenotype in lwd1lwd2 plants is contributed by the significant phase shift of CO and, therefore, an increased expression of FT before dusk under SD conditions. Our data imply that LWD1/LWD2 proteins function in close proximity to the circadian oscillators for the regulation of photoperiod sensing.
2008-10-08 | GSE11762 | GEO
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
2015-07-26 | E-GEOD-70533 | biostudies-arrayexpress
Project description:Transcriptome analysis has revealed a light-regulated WD (tryptophan and aspartate)-containing protein, LWD1. LWD1 and LWD2 share greater than 90% amino acid sequence homology. The lack of phenotype changes in the lwd1 or lwd2 single mutant implies that the proteins function redundantly. The lwd1lwd2 double mutant, however, has an early flowering phenotype under both long-day (LD) and short-day (SD) conditions. Functional complementation experiment revealed that LWDs are indeed responsible for the defect in photoperiod sensing in lwd1lwd2 double mutant plants. The expression of LWD1 exhibits a diurnal pattern and peaks before dawn. The period length of oscillator (CCA1, LHY, TOC1 and ELF4) and output (CCR2 and CAB2) genes in the lwd1lwd2 double mutant is significantly shorter than that in wild-type Arabidopsis under free running condition. Under entrainment conditions, the expression phase of oscillator (CCA1, LHY, TOC1 and ELF4) and output (GI, FKF1, CDF1, CO and FT) genes shifts ~3 hr forward in the lwd1lwd2 double mutant. Our data indicated that the early flowering phenotype in lwd1lwd2 plants is contributed by the significant phase shift of CO and, therefore, an increased expression of FT before dusk under SD conditions. Our data imply that LWD1/LWD2 proteins function in close proximity to the circadian oscillators for the regulation of photoperiod sensing. Experiment Overall Design: Two biological replicates were performed to examine the differential gene expression between wild-type and lwd1lwd2 double mutant. The plants were grown under 12 h L/ 12 h D for 31 days before harvesting their above ground tissues at ZT5-9.
2008-10-26 | E-GEOD-11762 | biostudies-arrayexpress