Project description:Circadian rhythms are present across almost all species and affect several physiological and behavioral aspects of living organisms. The evolutionary advantage conferred by these rhythms could be their anticipatory properties. In the nervous system, anticipation is particularly interesting due to the spatiotemporal constraints derived by the highly compartmentalized neuronal structure. Previous work has confirmed that 900 genes are expressed in the mouse forebrain in robustly rhythmic fashion, and 180 transcripts are equally robustly circadian at the synapse. Interestingly, mRNAs are found in higher amounts at the end of the dark phase, and decrease exponentially during the first hours of light. This pattern resembles the “sawtooth” pattern of homeostatic sleep pressure. To further characterize this phenotype we propose to compare the synaptic transcriptome of sleep deprived mice to its control base line. This work would shed light into the emerging field of synaptic RNA transport and translation and its regulatory inputs. Hopefully, the results will yield to two different findings: the circadian and activity potential to regulate synaptic transport of RNA and the classification of transcripts deferentially regulated by both processes.
Project description:The circadian clock drives daily changes of physiology, including sleep-wake cycles, by regulating transcription, protein abundance and function. Circadian phosphorylation controls cellular processes in peripheral organs, but little is known about its role in brain function and synaptic activity. We applied advanced quantitative phosphoproteomics to mouse forebrain synaptoneurosomes isolated across 24h, accurately quantifying almost 8,000 phosphopeptides. Remarkably, half of the synaptic phosphoproteins, including numerous kinases, had large-amplitude rhythms peaking at rest-activity and activity-rest transitions. Bioinformatic analyses revealed global temporal control of synaptic function via phosphorylation, including synaptic transmission, cytoskeleton reorganization and excitatory/inhibitory balance. Remarkably, sleep deprivation abolished 98% of all phosphorylation cycles in synaptoneurosomes, indicating that sleep-wake cycles rather than circadian signals are main drivers of synaptic phosphorylation, responding to both sleep and wake pressures.
Project description:Alignment of fasting and feeding with the sleep/wake cycle is coordinated by hypothalamic neurons, though the underlying molecular programs remain incompletely understood. Here we demonstrate that the clock transcription pathway maximizes eating during wakefulness and glucose production during sleep through transcription pathway maximizes eating during autonomous circadian regulation of NPY/AgRP neurons. Tandem profiling of whole cell and ribosome-bound mRNAs in morning and evening under dynamic fasting and fed conditions identified temporal control of activity-dependent gene repertoires in AgRP neurons central to synaptogenesis, bioenergetics, and neurotransmitter and peptidergic signaling. Synaptic and circadian pathways were specific to whole cell RNA analyses, while bioenergetic pathways were selectively enriched in the ribosome-bound transcriptome. Finally, we demonstrate that the AgRP clock mediates the transcriptional food acquisition with sleep/wake state. response to leptin. Our results reveal that time-of-day restriction in transcriptional control of energy-sensing neurons underlies the alignment of hunger and day restriction in transcriptional control of energy-sensing neurons underlies the alignment of hunger and food acquisition with sleep/wake state.
Project description:<p>Sleep is essential for life. A good night's sleep is pleasurable and sleep deprivation is stressful. Prolonged sleep loss impairs temperature control, metabolism, immunity, and ultimately leads to death. Extensive observational and epidemiological evidence indicates that optimal sleep duration of 8 hours is associated with the maintenance of good health. In our society, however, most people only get 6.5 - 7 hours. Suboptimal sleep duration has a strong association with mortality and morbidity. Lack of sleep has been linked to cardiovascular diseases, obesity, hypertension, type 2 diabetes, and other health/cognition conditions. It is clear that the biological need for sleep varies dramatically among humans. Sleep and circadian disorders can include Familial Advanced Sleep Phase (FASP), Delayed Sleep Phase (DSP), Advanced Sleep Phase (ASP), Natural Short Sleepers (NSS) or Long Sleeping. In example, Natural Short Sleepers (NSS) have a lifelong tendency to sleep only 4 - 6 hours per night and to awaken refreshed and energetic. Natural Long Sleepers biologically require 9 - 10 hours/night to feel well rested.</p> <p>The 'Sleep and Circadian Disorders Study' (SACDS) at the University of California San Francisco, set out to investigate the mechanisms involved in regulating sleep duration, patterns and sleep quality regulation by identifying and characterization of individuals and families with unusual sleep and circadian rhythm behavior patterns.</p> <p>SACDS participants were screened with a "General Sleep Questionnaire" that inquired about multiple aspects of sleep, including habitual work-day versus non-work day sleep-wake schedules, permits calculation of subjective habitual initial sleep onset, final sleep offset, and number of awakenings. There was an additional screening process including demographic data, sleep, mood, behavioral and general medical questionnaires, plus the study consent.</p> <p>After the extensive screening of 117 participants, blood samples were collected from 38 individuals and of those 10 samples were chosen for whole exome sequencing analysis.</p>
Project description:Inadequate sleep prevails in modern society and it impairs the circadian transcriptome. However, whether acute sleep deprivation has impact on the circadian rhythms is not clear. Here, we show that in mouse lung, a 10-hour acute sleep deprivation can alter the circadian expression of approximally 3,000 genes. We found that circadian rhythm disappears in genes related to metabolism and signaling pathways regulating protein phosphorylation after acute sleep deprivation, while the core circadian regulators do not change much in rhythmicity. Importantly, the strong positive correlation between mean expression and amplitude (E-A correlation) of cycling genes has been validated in both control and sleep deprivation conditions, supporting the energetic cost optimization model of circadian gene expression. Thus, we reveal that acute sleep deprivation leads to a profound change in the circadian gene transcription that influences the biological functions in lung.
Project description:The sleep-wake cycle is determined by a circadian and a sleep homeostatic process. However, the molecular impact of these two processes and their interaction on different cell populations in the brain remain unknown. To fill this gap, we have profiled the single-cell transcriptome of adult fruit fly brains across the sleep-wake cycle and different circadian times. We show cell type-specific transcriptomic changes between sleep/wakefulness states, different levels of sleep drive, and varying circadian times, with glial cells displaying the largest variations. Furthermore, the cell types whose transcriptomic dynamics correlate with the sleep homeostat or circadian clock are largely non-overlapping, with the exception of glial cells. Diminishing the circadian clock only in glial cells impairs the homeostatic sleep rebound after sleep deprivation. These findings reveal a comprehensive picture of different effects of sleep homeostatic and circadian processes on different cell types and define glial cells as the interaction sites of these two processes to determine sleep-wake dynamics.
Project description:Sleep has been strongly implicated in learning and especially in the reprocessing of recently acquired memory. Children with intellectual disability (ID) tend to have sleep-wake disturbances, which may contribute to the pathophysiology of the disease. As far as sleep is, in part, a circadian process, we decided to study rhythmic gene expression in hippocampus, a brain structure, which plays a key role in memory in human and rodents. By investigating the transcriptome of mouse adult hippocampus, we report here the identification of 663 circadian rhythm (CR)-regulated genes, which have been clustered in four categories, based on their temporal pattern of expression. In addition to the standard core-clock genes, enrichment analysis of the hippocampal CR-regulated genes revealed the presence of several transcription factors, underlying the existence of an inter-regulation of genes' expression between clusters. Interestingly, these hippocampal circadian rhythm-regulated genes are very enriched in sleep/wakefulness related genes. We show here that glucocorticoid signaling, already shown to be involved in memory regulation, is a circadian regulated pathway in hippocampus. Furthermore, we identified a list of 30 CR-regulated ID genes. Our results demonstrate that hippocampus can be considered as a peripheral oscillator and illustrate the link between circadian rhythm, sleep, intellectual disability and memory consolidation. In order to identify circadian rhythm-regulated genes in mouse hippocampus, we realized a study in dark-dark conditions, thus allowing to overcome the effects induced by light changes. To systematically identify genes with circadian regulated expression, RNA samples from the hippocampus of three mice at four Circadian Time (CT) points were used for expression profiling using Agilent microarray technology. The dark/dark period started at 7 p.m. The Circadian Time (CT) 18 samples were taken after 30 h of continuous dark; the other circadian times followed at 6-h intervals: CT0, CT6 and CT12 after 36, 42 and 48 h of continuous darkness, respectively.
Project description:The metronome-like circadian regulation of sleep timing must still adapt to an uncertain environment. Recent studies in Drosophila indicate that neuromodulation not only plays a key role in clock neuron synchronization but also affects interactions between the clock network and brain sleep centers. We show here that the targets of neuromodulators, G-Protein Coupled Receptors (GPCRs), are highly enriched in the fly brain circadian clock network. Single cell sequencing indicates that they are not only enriched, but they are also differentially expressed and contribute to clock neuron identity. We generated a comprehensive guide library to mutagenize individual GPCRs in specific neurons and verified the strategy by introducing a targeted sequencing approach. Combined with a behavioral screen, the mutagenesis strategy revealed a novel role of dopamine in sleep regulation by identifying two dopamine receptors and a clock neuron subpopulation that gate the timing of sleep.