Project description:As the primary source of norepinephrine (NE) in the brain, the locus coeruleus (LC) regulates both arousal and stress responses1,2. However, how local neuromodulatory inputs contribute to LC function remains unresolved. Here we identify a network of transcriptionally and functionally diverse GABAergic neurons in the LC dendritic field that integrate distant inputs and modulate modes of LC firing to control arousal. We define peri-LC anatomy using viral tracing and combine single-cell RNA sequencing and spatial transcriptomics to molecularly define both LC and peri-LC cell types. We identify several cell types which underlie peri-LC functional diversity using a series of complementary approaches in behaving mice. Our findings indicate that LC and peri-LC neurons comprise transcriptionally and functionally heterogenous neuronal populations, alongside anatomically segregated features which coordinate specific influences on behavioral arousal and avoidance states. Defining the molecular, cellular and functional diversity in the LC provides a road map for understanding the neurobiological basis of arousal alongside hyperarousal-related neuropsychiatric phenotypes.
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:Comparative transcriptomics of the garden dormouse hypothalamus during early torpor, late torpor and interbout arousal of hibernation
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.
Project description:U2OS cells harbor a circadian clock but express only a few rhythmic genes in constant conditions. We identified 3040 binding sites of the circadian regulators BMAL1, CLOCK and CRY1 in the U2OS genome. Most binding sites even in promoters do not correlate with detectable rhythmic transcript levels. Luciferase fusions reveal that the circadian clock supports robust but low amplitude transcription rhythms of representative promoters. However, rhythmic transcription of these potentially clock-controlled genes is masked by non-circadian transcription that overwrites the weaker contribution of the clock in constant conditions. Our data suggest that U2OS cells harbor an intrinsically rather weak circadian oscillator. The oscillator has the potential to regulate a large number of genes. The contribution of circadian versus non-circadian transcription is dependent on the metabolic state of the cell and may determine the apparent complexity of the circadian transcriptome. Analysis of temporal expression profiles of 5708 expressed genes in synchronized U2OS cells. A 60k customized microarray was designed for 6356 genes, which corresponds to roughly one fourth of the human genome. 1373 genes were assigned to circadian regulator binding sites (CRBSs), 1503 genes were specifically selected in addition to a set of 3480 random genes. For each gene 10 independent probes in two microarray replicates were performed to increase reliability of the data.
Project description:Physiology is regulated by interconnected cell and tissue circadian clocks. Disruption of the rhythms generated by this interconnectedness is associated with metabolic disease. Here we tested the interactions between clocks in two critical components of organismal metabolism – liver and skeletal muscle – by rescuing clock function either in each organ separately, or in both organs simultaneously, in otherwise clock-less mice. Experiments revealed that individual clocks are partially sufficient for tissue glucose metabolism, yet the connections between both tissue clocks coupled with daily feeding rhythms maximizes systemic glucose tolerance. This synergy relies in part on local transcriptional control of the glucose machinery, feeding-responsive signals such as insulin, and metabolic cycles that connect the muscle and liver. We posit that spatiotemporal mechanisms of muscle and liver play an essential role in the maintenance of systemic glucose homeostasis, and that disrupting this diurnal coordination can contribute to the metabolic disease.
Project description:Mammalian circadian clocks precisely control the rhythms of behavior and physiology, and can be reset by various environmental signals. While the light-dark (LD) cycle resets the master clock, timed food intake is a potent synchronizer of peripheral clocks. As the largest metabolic organ, the liver sensitively responds to the food signals and secrets hepatokines, leading to the robust regulation of metabolic and clock processes. However, it remains unknown which hepatokine mediates the food-driven resetting of the liver clock independent of the master clock. In our current study, we clustered high-throughput RNA sequencing results to screen out candidate genes that mediate the food-driven resetting of the liver clock