Project description:Mammalian transcriptomes display complex circadian rhythms with multiple phases of gene expression that cannot be accounted for by current models of the molecular clock. We have determined the underlying mechanisms by measuring nascent RNA transcription around the clock in mouse liver. Unbiased examination of eRNAs that cluster in specific circadian phases identified functional enhancers driven by distinct transcription factors (TFs). We further identify on a global scale the components of the TF cistromes that function to orchestrate circadian gene expression. Integrated genomic analyses also revealed novel mechanisms by which a single circadian factor controls opposing transcriptional phases. These findings shed new light on the diversity and specificity of TF function in the generation of multiple phases of circadian gene transcription in a mammalian organ.
Project description:Mammalian transcriptomes display complex circadian rhythms with multiple phases of gene expression that cannot be accounted for by current models of the molecular clock.M-BM- We have determined the underlyingM-BM- mechanisms by measuring nascent RNA transcription around the clock in mouse liver. Unbiased examination of eRNAs that cluster in specific circadian phasesM-BM- identified functional enhancers driven by distinct transcription factors (TFs). We further identify on a global scale the components of the TF cistromes that function to orchestrate circadian gene expression. Integrated genomicM-BM- analysesM-BM- also revealed novel mechanisms by which a single circadian factor controls opposing transcriptional phases. These findings shed new light on the diversity and specificity of TF function in the generation of multiple phases of circadian gene transcription in a mammalian organ. Nascent RNA transcripts in mouse liver were profiled at 8 time points of the 24 hour light-dark cycle. Static state mRNAs in WT and Rev-erbA -/- mice were profiled using microarray (GSE59460).
Project description:Mammalian transcriptomes display complex circadian rhythms with multiple phases of gene expression that cannot be accounted for by current models of the molecular clock. We have determined the underlying mechanisms by measuring nascent RNA transcription around the clock in mouse liver. Unbiased examination of eRNAs that cluster in specific circadian phases identified functional enhancers driven by distinct transcription factors (TFs). We further identify on a global scale the components of the TF cistromes that function to orchestrate circadian gene expression. Integrated genomic analyses also revealed novel mechanisms by which a single circadian factor controls opposing transcriptional phases. These findings shed new light on the diversity and specificity of TF function in the generation of multiple phases of circadian gene transcription in a mammalian organ. The goal of this experiment was to determine direct targets of Rev-erb{alpha} in mouse liver. All samples were collected at ZT10, when Rev-erb{alpha} protein levels and genomic binding are maximal. All mice were housed and harvested together (n=5 per genotype). All mice were male, 10-12 week old on C57Bl/6 background. RNA was extracted, processed, and hybridized from each mouse liver individually (each sample represents a single mouse).
Project description:Mammalian transcriptomes display complex circadian rhythms with multiple phases of gene expression that cannot be accounted for by current models of the molecular clock. We have determined the underlying mechanisms by measuring nascent RNA transcription around the clock in mouse liver. Unbiased examination of eRNAs that cluster in specific circadian phases identified functional enhancers driven by distinct transcription factors (TFs). We further identify on a global scale the components of the TF cistromes that function to orchestrate circadian gene expression. Integrated genomic analyses also revealed novel mechanisms by which a single circadian factor controls opposing transcriptional phases. These findings shed new light on the diversity and specificity of TF function in the generation of multiple phases of circadian gene transcription in a mammalian organ. The goal of this experiment was to determine direct targets of Rev-erb{alpha} in mouse liver. All samples were collected at ZT10, when Rev-erb{alpha} protein levels and genomic binding are maximal.
Project description:Genome-wide rhythmic modulation of RNAPII occupancy and histone acetylation modifications are highly coordinated with rhythmic gene expression, and dynamically modulates diurnal 3D genome architecture remodeling. The rhythmic genes at AM circadian phase and target genes of transcription factors (TFs) are enriched within limited spatial clusters, which forming subnuclear organization hubs to coordinate looping gene expression. Core circadian clock genes related chromatin connectivity networks suggested they co-localized within the same ?transcriptional factory? and define a distinct nuclear landscape and circadian outputs in the AM and PM. Our findings uncover novel diurnal fundamental genome folding principles in plants, and reveal a distinct higher-order chromosome organization that is crucial for coordinating diurnal dynamics of transcriptional regulation.
Project description:Genome-wide rhythmic modulation of RNAPII occupancy and histone acetylation modifications are highly coordinated with rhythmic gene expression, and dynamically modulates diurnal 3D genome architecture remodeling. The rhythmic genes at AM circadian phase and target genes of transcription factors (TFs) are enriched within limited spatial clusters, which forming subnuclear organization hubs to coordinate looping gene expression. Core circadian clock genes related chromatin connectivity networks suggested they co-localized within the same “transcriptional factory” and define a distinct nuclear landscape and circadian outputs in the AM and PM. Our findings uncover novel diurnal fundamental genome folding principles in plants, and reveal a distinct higher-order chromosome organization that is crucial for coordinating diurnal dynamics of transcriptional regulation.
Project description:Genome-wide rhythmic modulation of RNAPII occupancy and histone acetylation modifications are highly coordinated with rhythmic gene expression, and dynamically modulates diurnal 3D genome architecture remodeling. The rhythmic genes at AM circadian phase and target genes of transcription factors (TFs) are enriched within limited spatial clusters, which forming subnuclear organization hubs to coordinate looping gene expression. Core circadian clock genes related chromatin connectivity networks suggested they co-localized within the same ?transcriptional factory? and define a distinct nuclear landscape and circadian outputs in the AM and PM. Our findings uncover novel diurnal fundamental genome folding principles in plants, and reveal a distinct higher-order chromosome organization that is crucial for coordinating diurnal dynamics of transcriptional regulation.
Project description:Over the past decade, genome-wide assays have underscored the broad sweep of circadian gene expression. A substantial fraction of the transcriptome undergoes oscillations in many organisms and tissues, which governs the many biochemical, physiological and behavioral functions under circadian control. Based predominantly on the transcription feedback loops important for core circadian timekeeping, it is commonly assumed that this widespread mRNA cycling reflects circadian transcriptional cycling. To address this issue, we directly measured dynamic changes in mouse liver transcription using Nascent-Seq. Many genes are rhythmically transcribed over the 24h day, which include precursors of several non-coding RNAs as well as the expected set of core clock genes. Surprisingly however, nascent RNA rhythms overlap poorly with mRNA abundance rhythms assayed by RNA-seq. This is because most mouse liver genes with rhythmic mRNA expression manifest poor transcriptional rhythms, indicating a prominent role of post-transcriptional regulation in setting mRNA cycling amplitude. To gain further insight into circadian transcriptional regulation, we also characterized the rhythmic transcription of liver genes targeted by the transcription factors CLOCK and BMAL1; they directly target other core clock genes and sit at the top of the molecular circadian clock hierarchy in mammals. CLK:BMAL1 rhythmically bind at the same discrete phase of the circadian cycle to all target genes, which not surprisingly have a much higher percentage of rhythmic transcription than the genome as a whole. However, there is a surprisingly heterogeneous set of cycling transcription phases of direct target genes, which even include core clock genes. This indicates a disconnect between rhythmic DNA binding and the peak of transcription, which is likely due to other transcription factors that collaborate with CLK:BMAL1. In summary, the application of Nascent-Seq to a mammalian tissue provides surprising insights into the rhythmic control of gene expression and should have broad applications beyond the analysis of circadian rhythms. CLK and BMAL1 DNA binding profile in the mouse liver at ZT8, sequenced along an Input sample using GAII (ChIP-Seq) Supplementary file ChIPSeq_Mouse_Liver_Processed_data_Table1.txt represents annotated CLK and BMAL1 peaks.
Project description:<p>Circadian clocks coordinate mammalian behaviour and physiology enabling organisms to anticipate 24-hour cycles. Transcription-translation feedback loops are thought to drive these clocks in most of mammalian cells. However, red blood cells (RBCs), which do not contain a nucleus, and cannot perform transcription or translation, nonetheless exhibit circadian redox rhythms. Here we show human RBCs display circadian regulation of glucose metabolism, which is required to sustain daily redox oscillations. We found daily rhythms of metabolite levels and flux through glycolysis and the pentose phosphate pathway (PPP). We show that inhibition of critical enzymes in either pathway abolished 24-hour rhythms in metabolic flux and redox oscillations, and determined that metabolic oscillations are necessary for redox rhythmicity. Furthermore, metabolic flux rhythms also occur in nucleated cells, and persist when the core transcriptional circadian clockwork is absent in Bmal1 knockouts. Thus, we propose that rhythmic glucose metabolism is an integral process in circadian rhythms.</p><p><br></p><p><strong>GC-MS assay</strong> protocols and data are reported in the current study <strong>MTBLS1286</strong>.</p><p><strong>LC-MS assay</strong> protocols and data for this study are reported in <a href='https://www.ebi.ac.uk/metabolights/MTBLS1285' rel='noopener noreferrer' target='_blank'><strong>MTBLS1285</strong></a>.</p>