Project description:This SuperSeries is composed of the following subset Series: GSE34018: Integral roles for Rev-erb alpha and Rev-erb beta in the circadian clock function [Expression array] GSE34019: Integral roles for Rev-erb alpha and Rev-erb beta in the circadian clock function [ChIP_seq] Refer to individual Series
Project description:Disruption of the Circadian Clock within the Cardiomyocyte Influences Myocardial Contractie Function, Metabolism, and Gene Expression Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally-based molecular mechanism in cardiovascular biology is poorly understood. We hypothesized that the circadian clock within the cardiomyocyte influences diurnal variations in myocardial biology. We therefore generated a cardiomyocyte-specific circadian clock mutant (CCM) mouse, in order to test this hypothesis. At 12 weeks of age, CCM mice exhibit normal myocardial contractile function in vivo, as assessed by echocardiography. Radiotelemetry studies reveal attenuation of heart rate diurnal variations and bradycardia in CCM mice (in the absence of conduction system abnormalities). Reduced heart rate persisted in CCM hearts perfused ex vivo in the working mode, highlighting the intrinsic nature of this phenotype. Wild-type, but not CCM, hearts exhibited a marked diurnal variation in responsiveness to an elevation in workload (80mmHg plus 1 microM epinephrine) ex vivo, with a greater increase in cardiac power and efficiency during the dark (active) phase versus the light (inactive) phase. Moreover, myocardial oxygen consumption and fatty acid oxidation rates were increased, while cardiac efficiency was decreased, in CCM hearts. These observations were associated with no alterations in mitochondrial content or structure, and modest mitochondrial dysfunction, in CCM hearts. Gene expression microarray analysis identified 548 and 176 genes in atria and ventricles, respectively, whose normal diurnal expression patterns were altered in CCM mice. These studies suggest that the cardiomyocyte circadian clock influences myocardial contractile function, metabolism, and gene expression. Keywords: Comparison of circadian oscillations in gene expression in hearts taken from wildtype and transgenic animals
Project description:Observational, non randomized study aimed at measuring the circadian rhythms in the urinary concentrations of physiological modified nucleosides in 30 patients with metastatic colorectal cancer and in 30 age and sex-matched healthy subjects.
Project description:Casein Kinase 2 (CK2) is an evolutionarily conserved kinase protein that phosphorylates a plethora of cellular target protein involved in processes including DNA repair, cell cycle control, and circadian rhythms. CK2 is functionally conserved across all eukaryotes, although the substrate proteins identified in targeted experiments on a diverse range of complex tissues are often different. A growing interest exists to identify conserved, core signalling principles essential to eukaryotic life. To efficiently study generic roles of CK2 in the cellular circadian clock, we used a minimal eukaryotic model organism (Ostreococcus tauri). Overexpression of CK2 leads to a slow circadian rhythm, verifying functional conservation of CK2 in cellular timekeeping. CK2 activity contributes more strongly to the clock around dusk than around dawn, and analysis of the phospho-proteome at this time revealed a strong overrepresentation of potential CK2 sites. Large changes to the phospho-proteome are reported here upon overexpression of CK2, identifying a set of CK2-responsive phospho-sites. To identify more CK2-specific phosphorylation events, the phospho-proteome of cells treated with CK2 inhibitor were analysed and compared to the overexpression lines. We thus report a full inventory of the CK2-responsive phospho-proteome to inform studies into CK2 activity in the circadian clock of more complex tissues, as science moves to understand and modulate cellular circadian rhythms to help us negate the negative effects of shiftwork or cross-continental travel.
Project description:The circadian clock acts at the genomic level to coordinate internal behavioral and physiologic rhythms via the CLOCK-BMAL transcriptional heterodimer. Although the nuclear receptors REV-ERBα and β have been proposed to contribute to clock function, their precise roles and importance remain unresolved. To establish their regulatory potential we generated comparative cistromes of both Rev-erb isoforms, which revealed shared recognition at over ~50% of their total sites and extensive overlap with the master clock regulator Bmal. While Rev-erbα has been shown to directly regulate Bmal expression, the cistromic analysis reveals a more profound connection between Bmal and Rev-erbα and β regulatory circuits than previously suspected. Genes within the intersection of the Bmal and Rev-erb cistromes are highly enriched for both clock and metabolic functions. As predicted by the cistromic analysis, dual depletion of Rev-erbα/β function by creating double-knockout mice (DKOs) profoundly disrupted circadian expression of core clock and lipid homeostatic genes. As a result, DKOs show strikingly altered circadian wheel-running behavior and deregulated lipid metabolism. These data reveal an integral role of Rev-erbα/β in clock function as well as provide a cistromic basis for the integration of circadian rhythm and metabolism. Identification of Reverb alpha and Reverb beta binding sites in mouse liver at ZT8
Project description:The long non-coding RNA (lncRNA) Xist is a master regulator of X-chromosome inactivation in mammalian cells. Models for how Xist and other lncRNAs function depend on thermodynamically stable secondary and higher-order structures that RNAs can form in the context of a cell. Probing accessible RNA bases can provide data to build models of RNA conformation that provide insight into RNA function, molecular evolution, and modularity. To study the structure of Xist in cells, we built upon recent advances in RNA secondary structure mapping and modeling to develop Targeted Structure-Seq, which combines chemical probing of RNA structure in cells with target-specific massively parallel sequencing. By enriching for signals from the RNA of interest, Targeted Structure-Seq achieves high coverage of the target RNA with relatively few sequencing reads, thus providing a targeted and scalable approach to analyze RNA conformation in cells. We use this approach to probe the full-length Xist lncRNA to develop new models for functional elements within Xist, including the repeat A element in the 5'-end of Xist. This analysis also identified new structural elements in Xist that are evolutionarily conserved, including a new element proximal to the C repeats that is important for Xist function. Examination of dimethylsufate reactivity of Xist lncRNA and 18S rRNA in cells using targeted reverse transcription to determine reactivity, and comparisons with untreated control samples.
Project description:This study examines the best way to teach genetics to family medicine residents. First year family medicine residents at the University of Toronto will be taught basic clinical genetics as well as a specific disease in genetics via 3 different educational methods. All participants will undergo an oral examination and written knowledge test 3 months after this education. Results between groups will be compared, and the best way to teach genetics to residents determined.