DEC2 modulates orexin expression and regulates sleep.

Adequate sleep is essential for physical and mental health. We previously identified a missense mutation in the human DEC2 gene (BHLHE41) leading to the familial natural short sleep behavioral trait. DEC2 is a transcription factor regulating the circadian clock in mammals, although its role in sleep regulation has been unclear. Here we report that prepro-orexin, also known as hypocretin (Hcrt), gene expression is increased in the mouse model expressing the mutant hDEC2 transgene (hDEC2-P384R). Prepro-orexin encodes a precursor protein of a neuropeptide producing orexin A and B (hcrt1 and hcrt2), which is enriched in the hypothalamus and regulates maintenance of arousal. In cell culture, DEC2 suppressed prepro-orexin promoter-luc (ore-luc) expression through cis-acting E-box elements. The mutant DEC2 has less repressor activity than WT-DEC2, resulting in increased orexin expression. DEC2-binding affinity for the prepro-orexin gene promoter is decreased by the P384R mutation, likely due to weakened interaction with other transcription factors. In vivo, the decreased immobility time of the mutant transgenic mice is attenuated by an orexin receptor antagonist. Our results suggested that DEC2 regulates sleep/wake duration, at least in part, by modulating the neuropeptide hormone orexin

A PERIOD3 variant causes a circadian phenotype and is associated with a seasonal mood trait.

In humans, the connection between sleep and mood has long been recognized, although direct molecular evidence is lacking. We identified two rare variants in the circadian clock gene PERIOD3 (PER3-P415A/H417R) in humans with familial advanced sleep phase accompanied by higher Beck Depression Inventory and seasonality scores. hPER3-P415A/H417R transgenic mice showed an altered circadian period under constant light and exhibited phase shifts of the sleep-wake cycle in a short light period (photoperiod) paradigm. Molecular characterization revealed that the rare variants destabilized PER3 and failed to stabilize PERIOD1/2 proteins, which play critical roles in circadian timing. Although hPER3-P415A/H417R-Tg mice showed a mild depression-like phenotype, Per3 knockout mice demonstrated consistent depression-like behavior, particularly when studied under a short photoperiod, supporting a possible role for PER3 in mood regulation. These findings suggest that PER3 may be a nexus for sleep and mood regulation while fine-tuning these processes to adapt to seasonal changes

Neuronal protease-activated receptor 1 drives synaptic retrograde signaling mediated by the endocannabinoid 2-arachidonoylglycerol

金沢大学医薬保健研究域保健学系Protease-activated receptor 1 (PAR1) is a member of the G-protein coupled receptors that are proteolytically activated by serine proteases. Recent studies suggest a definite contribution of PAR1 to brain functions, including learning and memory. However, cellular mechanisms by which PAR1 activation influences neuronal activity are not well understood. Here we show that PAR1 activation drives retrograde endocannabinoid signaling and thereby regulates synaptic transmission. In cultured hippocampal neurons from rat, PAR1 activation by thrombin or PAR1-specific peptide agonists transiently suppressed inhibitory transmission at cannabinoid-sensitive, but not cannabinoid-insensitive, synapses. The PAR1-induced suppression of synaptic transmission was accompanied by an increase in paired-pulse ratio, and was blocked by a cannabinoid CB 1 receptor antagonist. The PAR1-induced suppression was blocked by pharmacological inhibition of postsynaptic diacylglycerol lipase (DGL), a key enzyme for biosynthesis of the major endocannabinoid 2-arachidonoylglycerol (2-AG), and was absent in knock-out mice lacking the α isoform of DGL. The PAR1-induced IPSC suppression remained intact under the blockade of metabotropic glutamate receptors and was largely resistant to the treatment that blocked Ca2+ elevation in glial cells following PAR1 activation, which excludes the major contribution of glial PAR1 in IPSC suppression. We conclude that activation of neuronal PAR1 triggers retrograde signaling mediated by 2-AG, which activates presynaptic CB1 receptors and suppresses transmitter release at hippocampal inhibitory synapses. Copyright © 2011 the authors

The Endocannabinoid 2-Arachidonoylglycerol Produced by Diacylglycerol Lipase α Mediates Retrograde Suppression of Synaptic Transmission

SummaryEndocannabinoids are released from postsynaptic neurons and cause retrograde suppression of synaptic transmission. Anandamide and 2-arachidonoylglycerol (2-AG) are regarded as two major endocannabinoids. To determine to what extent 2-AG contributes to retrograde signaling, we generated and analyzed mutant mice lacking either of the two 2-AG synthesizing enzymes diacylglycerol lipase α (DGLα) and β (DGLβ). We found that endocannabinoid-mediated retrograde synaptic suppression was totally absent in the cerebellum, hippocampus, and striatum of DGLα knockout mice, whereas the retrograde suppression was intact in DGLβ knockout brains. The basal 2-AG content was markedly reduced and stimulus-induced elevation of 2-AG was absent in DGLα knockout brains, whereas the 2-AG content was normal in DGLβ knockout brains. Morphology of the brain and expression of molecules required for 2-AG production other than DGLs were normal in the two knockout mice. We conclude that 2-AG produced by DGLα, but not by DGLβ, mediates retrograde suppression at central synapses

Serotonergic Input to Orexin Neurons Plays a Role in Maintaining Wakefulness and REM Sleep Architecture

Neurons expressing neuropeptide orexins (hypocretins) in the lateral hypothalamus (LH) and serotonergic neurons in the dorsal raphe nucleus (DR) both play important roles in the regulation of sleep/wakefulness states, and show similar firing patterns across sleep/wakefulness states. Orexin neurons send excitatory projections to serotonergic neurons in the DR, which express both subtypes of orexin receptors (Mieda et al., 2011), while serotonin (5-HT) potently inhibits orexin neurons through activation of 5HT1A receptors (5HT1ARs). In this study, we examined the physiological importance of serotonergic inhibitory regulation of orexin neurons by studying the phenotypes of mice lacking the 5HT1A receptor gene (Htr1a) specifically in orexin neurons (ox5HT1ARKO mice). ox5HT1ARKO mice exhibited longer NREM sleep time along with decreased wakefulness time in the later phase of the dark period. We also found that restraint stress induced a larger impact on REM sleep architecture in ox5HT1ARKO mice than in controls, with a larger delayed increase in REM sleep amount as compared with that in controls, indicating abnormality of REM sleep homeostasis in the mutants. These results suggest that 5HT1ARs in orexin neurons are essential in the regulation of sleep/wakefulness states, and that serotonergic regulation of orexin neurons plays a crucial role in the appropriate control of orexinergic tone to maintain normal sleep/wake architecture

Ionotropic Glutamate Receptor AMPA 1 Is Associated with Ovulation Rate

Ionotropic glutamate receptors mediate most excitatory neurotransmission in the central nervous system by opening ion channels upon the binding of glutamate. Despite the essential roles of glutamate in the control of reproduction and anterior pituitary hormone secretion, there is a limited understanding of how glutamate receptors control ovulation. Here we reveal the function of the ionotropic glutamate receptor AMPA-1 (GRIA1) in ovulation. Based on a genome-wide association study in Bos taurus, we found that ovulation rate is influenced by a variation in the N-terminal leucine/isoleucine/valine-binding protein (LIVBP) domain of GRIA1, in which serine is replaced by asparagine. GRIA1Asn has a weaker affinity to glutamate than GRIA1Ser, both in Xenopus oocytes and in the membrane fraction of bovine brain. This single amino acid substitution leads to the decreased release of gonadotropin-releasing hormone (GnRH) in immortalized hypothalamic GT1-7 cells. Cows with GRIA1Asn have a slower luteinizing hormone (LH) surge than cows with GRIA1Ser. In addition, cows with GRIA1Asn possess fewer immature ovarian follicles before superovulation and have a lower response to hormone treatment than cows with GRIA1Ser. Our work identified that GRIA1 is a critical mediator of ovulation and that GRIA1 might be a useful target for reproductive therapy

Transformation-induced changes in the DNA-nuclear matrix interface, revealed by high-throughput analysis of DNA halos

In higher eukaryotic nuclei, DNA is periodically anchored to an extraction-resistant protein structure, via matrix attachment regions. We describe a refined and accessible method to non-subjectively, rapidly and reproducibly measure both size and stability of the intervening chromatin loops, and use it to demonstrate that malignant transformation compromises the DNA-nuclear matrix interface

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Spatial diversity in gene expression for VDCCγ subunit family in developing and adult mouse brains

The γ subunit of voltage-dependent Ca2+ channels (VDCCs) is characterized by molecular diversity and regulation of AMPA-type glutamate receptors as well as VDCCs. In the present study, we examined expressions for the VDCCγ1–8 subunit mRNAs in developing and adult mouse brains by in situ hybridization. In adult brains, the γ2 and γ7 subunit mRNAs were widely expressed in various grey matter regions with the highest level in cerebellar Purkinje cells and granule cells. The γ3 and γ8 subunit mRNAs predominated in the telencephalon, with the latter being at striking levels in the hippocampus. The γ4 subunit mRNA was enriched in the olfactory bulb, striatum, thalamus and hypothalamus. The γ5 subunit mRNA was abundant in the olfactory bulb, hippocampal CA2, thalamus, inferior colliculus and Bergmann glia. Transcripts of these subunits were detected in embryonic brains: some showed well-preserved spatial patterns (γ2, γ5, γ7 and γ8), while others underwent developmental up- (γ3) or down-regulation (γ4). In contrast, the γ1 and γ6 subunit mRNAs were negative or very low throughout brain development. Therefore, the present study has revealed spatial diversity in gene expression for individual VDCCγ subunits, presumably reflecting functional diversity of this protein family and their differential involvement in neural function