Project description:Imprinted genes are highly expressed in the hypothalamus, however whether specific imprinted genes affect hypothalamic neuromodulators and their functions is unknown. It has been suggested that Prader-Willi syndrome (PWS), a neurodevelopmental disorder caused by lack of paternal expression at the chromosome 15q11-q13, characterised with a hypothalamic insufficiency. Here we investigate the role of paternally expressed Snord116 gene within the context of sleep and metabolic abnormalities of PWS, and we report a novel role of this imprinted gene in the function and organisation of the two main neuromodulatory systems of the lateral hypothalamus (LH), namely the orexin (OX) and the melanin concentrating hormone (MCH). We observe that the dynamic between neuronal discharge in the LH and sleep-wake states of mice carrying the paternal deletion of the Snord116 (PWScrm+/p-) is compromised. This abnormal state-dependent neuronal activity is paralleled by a significant reduction of OX neurons in LH of mutants. Therefore, we propose that unbalance between OX- and MCH- expressing neurons in the LH of mutants reflects in a series of deficits manifested in the PWS, such as dysregulation of rapid eye movement (REM) sleep, food intake and temperature control.
Project description:Imprinted genes are highly expressed in the hypothalamus; however, whether specific imprinted genes affect hypothalamic neuromodulators and their functions is unknown. It has been suggested that Prader-Willi syndrome (PWS), a neurodevelopmental disorder caused by lack of paternal expression at chromosome 15q11-q13, is characterized by hypothalamic insufficiency. Here, we investigate the role of the paternally expressed Snord116 gene within the context of sleep and metabolic abnormalities of PWS, and we report a significant role of this imprinted gene in the function and organization of the 2 main neuromodulatory systems of the lateral hypothalamus (LH) - namely, the orexin (OX) and melanin concentrating hormone (MCH) - systems. We observed that the dynamics between neuronal discharge in the LH and the sleep-wake states of mice with paternal deletion of Snord116 (PWScrm+/p-) are compromised. This abnormal state-dependent neuronal activity is paralleled by a significant reduction in OX neurons in the LH of mutant mice. Therefore, we propose that an imbalance between OX- and MCH-expressing neurons in the LH of mutant mice reflects a series of deficits manifested in the PWS, such as dysregulation of rapid eye movement (REM) sleep, food intake, and temperature control.
Project description:The preoptic area of hypothalamus plays an important role in sleep homeostasis. We used snRNA-seq to identify neurons involved in homeostatic sleep response.
Project description:Hypothalamic hypocretin (HCRT) and melanin concentrating hormone (MCH) have multiple functions including sleep and metabolism. How these neuropeptides are produced and involved in divers functions remain unknown. We developed methods to sort and purify HCRT and MCH neurons from mouse hypothalamus. RNA-sequencing revealed key factors of fate determination for HCRT (Peg3, Ahr1, Six6, Nr2f2 and Prrx1) and MCH (Lmx1, Gbx2 and Peg3) neurons. Amongst these, loss of Peg3 in mice significantly reduces HCRT and MCH cell numbers while knock-down of Peg3 ortholog in zebrafish completely abolishes their expression resulting in a two fold increase in sleep. The transcriptome results were used to produce HCRT and MCH neurons from induced pluripotent stem cells (iPSCs) and ascorbic acid was found necessary for HCRT and BMP7 for MCH cell differentiation. Our results provide a platform to understand the development and expression of HCRT and MCH and their multiple functions in health and disease.
Project description:Sleep and affective behaviors are highly interrelated phenotypes, commonly altered in a variety of neuropsychiatric diseases, including major depressive disorder (MDD). To understand the transcriptomic organization underlying sleep and affective function, we studied a population of (C57BL/6J x 129S1/SvImJ) F2 mice by measuring 283 affective and sleep phenotypes and profiling gene expression across four brain regions, including the frontal cortex, hippocampus, thalamus, and hypothalamus. We identified converging molecular bases for sleep and affective phenotypes at both the single-gene and gene-network levels. Utilizing publicly available transcriptomic datasets collected from sleep-deprived mice and major depressive disorder (MDD) patients, we identified three cortical gene networks altered by sleep/wake changes and depression. The network-level actions of sleep loss and depression were opposite to each other, providing a mechanistic basis for the sleep disruptions commonly observed in depression as well as the reported acute antidepressant effects of sleep deprivation. We highlight one particular network composed of circadian rhythm regulators and neuronal activity-dependent immediate-early genes. The key upstream driver of this network, Arc, may act as a nexus linking sleep and depression. Our data provide mechanistic insights into the role of sleep in affective function and MDD.
Project description:Every day, we sleep for a third of the day. Sleep is important for cognition, brain waste clearance, metabolism, and immune responses. Homeostatic regulation of sleep is maintained by progressively rising sleep need during wakefulness, which then dissipates during sleep. The molecular mechanisms governing sleep are largely unknown. Here, we used a combination of single-cell RNA sequencing and cell-type specific proteomics to interrogate the molecular and functional underpinnings of sleep. Different cell-types in the brain regions show similar transcriptional response to sleep need whereas sleep deprivation changes overall expression indicative of altered antigen processing, synaptic transmission and cellular metabolism in brainstem, cortex and hypothalamus, respectively. Increased sleep need enhances expression of transcription factor Sox2, Mafb, and Zic1 in brainstem; Hlf, Cebpb and Sox9 in cortex, and Atf3, Fosb and Mef2c in hypothalamus. Results from cell-type proteome analysis suggest that sleep deprivation changes abundance of proteins in cortical neurons indicative of altered synaptic vesicle cycles and glucose metabolism whereas in astrocytes it alters the abundance of proteins associated with fatty acid degradation. Similarly, phosphoproteomics of each cell type demonstrates large shifts in site-specific protein phosphorylation in neurons and astrocytes of sleep deprived mice. Our results indicate that sleep deprivation regulates transcriptional, translational and post-translational responses in a cell-specific manner and advances our understanding of the cellular and molecular mechanisms that govern sleep-wake homeostasis in mammals.
Project description:Examination of the effects of increasing durations of sleep deprivation. RNA is collected from two brain regions: cortex and hypothalamus.
Project description:The molecular mechanisms governing sleep are largely unknown. Here, we used a combination of single-cell RNA sequencing to interrogate the molecular and functional underpinnings of sleep. Different cell types in three important brain regions for sleep (brainstem, cortex and hypothalamus) had a similar transcriptional response to sleep need, with a large proportion of cells changing during recovery sleep. In contrast, sleep deprivation regulated expression of different functions in each brain region. This includes antigen processing, synaptic transmission and cellular metabolism in brainstem, cortex and hypothalamus, respectively. Increased sleep need enhances expression of the transcription factors Sox2, Mafb, and Zic1 in brainstem; Hlf, Cebpb and Sox9 in cortex, and Atf3, Fosb and Mef2c in hypothalamus. In turn, these transcription factors regulate downstream gene expression during sleep deprivation and recovery. In cortex, we also interrogated the proteome of two major cell types: neurons and astrocytes. We found surprising functional overlap of proteins that mediate vesicle and neurotransmitter transport in both cell types. In contrast, other functions were specific to each cell type.
Project description:Alterations in metabolism, sleep patterns, body composition, and hormone status are all key features of aging. The hypothalamus is a well-conserved brain region that controls these homeostatic and survival-related behaviors. Despite the importance of this brain region in healthy aging, little is known about the intrinsic features of hypothalamic aging. Here, we utilize single nuclei RNA-sequencing to assess the transcriptomes of 40,064 hypothalamic nuclei from young and aged female mice. We identify cell type-specific signatures of aging in neurons, astrocytes, and microglia, as well as among the diverse collection of neuronal subtypes in this region. We uncover key changes in cell types critical for metabolic regulation and body composition, as well as in an area of the hypothalamus linked to cognition. In addition, our analysis reveals female-specific changes in sex chromosome regulation in the aging brain. This study identifies critical cell-specific features of the aging hypothalamus in mammals.