To address the contribution of transcriptional regulation to clock gene expression and to behavior, we generated a series of CRISPR-mediated deletions within two regions of the circadian gene (), an intronic E-box region and an upstream E-box region that are both recognized by the key transcription factor Clock (Clk) and its heterodimeric partner Cycle. The upstream deletions but not an intronic deletion dramatically impact expression in fly heads; the biggest upstream deletion reduces peak RNA levels and RNA cycling amplitude to about 15% of normal, and there are similar effects on protein (TIM). The cycling amplitude of other clock genes is also strongly reduced, in these cases due to increases in trough levels.
View Article and Find Full Text PDFThe needs fulfilled by sleep are unknown, though the effects of insufficient sleep are manifold. To better understand how the need to sleep is sensed and discharged, much effort has gone into identifying the neural circuits involved in regulating arousal, especially those that promote sleep. In prevailing models, the dorsal fan-shaped body (dFB) plays a central role in this process in the fly brain.
View Article and Find Full Text PDFThe need to sleep is sensed and discharged in a poorly understood process that is homeostatically controlled over time. In flies, different contributions to this process have been attributed to peripheral ppk and central brain neurons, with the former serving as hypothetical inputs to the sleep homeostat and the latter reportedly serving as the homeostat itself. Here we re-evaluate these distinctions in light of new findings using female flies.
View Article and Find Full Text PDFα7 nicotinic acetylcholine receptors (nAChRs) are widely expressed in the brain where they promote fast cholinergic synaptic transmission and serve important neuromodulatory functions. However, their high permeability to Ca also predisposes them to contribute to disease states. Here, using transfected HEK-tsa cells and primary cultured hippocampal neurons from male and female rats, we demonstrate that two proteins called Ly6h and NACHO compete for access to α7 subunits, operating together but in opposition to maintain α7 assembly and activity within a narrow range that is optimal for neuronal function and viability.
View Article and Find Full Text PDFSleep deprivation has long been known to impair cognition, but it has been difficult to distinguish whether loss or disruption of sleep is responsible. Now it appears that merely interrupting sleep is sufficient to interfere with memory formation.
View Article and Find Full Text PDFInsect olfactory receptors operate as ligand-gated ion channels that directly transduce odor stimuli into electrical signals. However, in the absence of any known intermediate transduction steps, it remains unclear whether and how these ionotropic inputs are amplified in olfactory receptor neurons (ORNs). Here, we find that amplification occurs in the Drosophila courtship-promoting ORNs through Pickpocket 25 (PPK25), a member of the degenerin/epithelial sodium channel family (DEG/ENaC).
View Article and Find Full Text PDFThe functions of sleep remain a mystery. Yet they must be important since sleep is highly conserved, and its chronic disruption is associated with various metabolic, psychiatric, and neurodegenerative disorders. This review will cover our evolving understanding of the mechanisms by which sleep is controlled and the complex relationship between sleep and disease states.
View Article and Find Full Text PDFDespite decades of intense study, the functions of sleep are still shrouded in mystery. The difficulty in understanding these functions can be at least partly attributed to the varied manifestations of sleep in different animals. Daily sleep duration can range from 4-20 hrs among mammals, and sleep can manifest throughout the brain, or it can alternate over time between cerebral hemispheres, depending on the species.
View Article and Find Full Text PDFTraumatic brain injury (TBI) is a major cause of morbidity and mortality worldwide. In addition, there has been a growing appreciation that even repetitive, milder forms of TBI (mTBI) can have long-term deleterious consequences to neural tissues. Hampering our understanding of genetic and environmental factors that influence the cellular and molecular responses to injury has been the limited availability of effective genetic model systems that could be used to identify the key genes and pathways that modulate both the acute and long-term responses to TBI.
View Article and Find Full Text PDFEndogenous circadian (∼24 h) clocks regulate key physiological and cognitive processes via rhythmic expression of clock genes. The main circadian pacemaker is the hypothalamic suprachiasmatic nucleus (SCN). Mood disorders, including bipolar disorder (BD), are commonly associated with disturbed circadian rhythms.
View Article and Find Full Text PDFLy6 proteins are endogenous prototoxins found in most animals. They show striking structural and functional parallels to snake α-neurotoxins, including regulation of ion channels and cholinergic signaling. However, the structural contributions of Ly6 proteins to regulation of effector molecules is poorly understood.
View Article and Find Full Text PDFSleep is thought to be controlled by two main processes: a circadian clock that primarily regulates sleep timing and a homeostatic mechanism that detects and responds to sleep need. Whereas abundant experimental evidence suggests that sleep need increases with time spent awake, the contributions of different brain arousal systems have not been assessed independently of each other to determine whether certain neural circuits, rather than waking per se, selectively contribute to sleep homeostasis. Using the fruit fly, Drosophila melanogaster, we found that sustained thermogenetic activation of three independent neurotransmitter systems promoted nighttime wakefulness.
View Article and Find Full Text PDFα4β2 nicotinic acetylcholine receptors (nAChRs) are abundantly expressed throughout the central nervous system and are thought to be the primary target of nicotine, the main addictive substance in cigarette smoking. Understanding the mechanisms by which these receptors are regulated may assist in developing compounds to selectively interfere with nicotine addiction. Here we report previously unrecognized modulatory properties of members of the Ly6 protein family on α4β2 nAChRs.
View Article and Find Full Text PDFMultiple neurological disorders are characterized by the abnormal accumulation of protein aggregates and the progressive impairment of complex behaviors. Our Drosophila studies demonstrate that middle-aged wild-type flies (WT, ~4-weeks) exhibit a marked accumulation of neural aggregates that is commensurate with the decline of the autophagy pathway. However, enhancing autophagy via neuronal over-expression of Atg8a (Atg8a-OE) reduces the age-dependent accumulation of aggregates.
View Article and Find Full Text PDFMany protein-coding genes identified by genome sequencing remain without functional annotation or biological context. Here we define a novel protein-coding gene, Nmf9, based on a forward genetic screen for neurological function. ENU-induced and genome-edited null mutations in mice produce deficits in vestibular function, fear learning and circadian behavior, which correlated with Nmf9 expression in inner ear, amygdala, and suprachiasmatic nuclei.
View Article and Find Full Text PDFA new study in fruit flies suggests modulation of neural activity links sleep and Alzheimer's disease. Both sleep loss and amyloid beta increase neural excitability, which reinforces the accumulation of amyloid beta and shortens lifespan.
View Article and Find Full Text PDFα7 nAChRs are expressed widely throughout the brain, where they are important for synaptic signaling, gene transcription, and plastic changes that regulate sensory processing, cognition, and neural responses to chronic nicotine exposure. However, the mechanisms by which α7 nAChRs are regulated are poorly understood. Here we show that trafficking of α7-subunits is controlled by endogenous membrane-associated prototoxins in the Ly6 family.
View Article and Find Full Text PDFBackground: Although sleep is conserved throughout evolution, the molecular basis of its control is still largely a mystery. We previously showed that the quiver/sleepless (qvr/sss) gene encodes a membrane-tethered protein that is required for normal sleep in Drosophila. SLEEPLESS (SSS) protein functions, at least in part, by upregulating the levels and open probability of Shaker (Sh) potassium channels to suppress neuronal excitability and enable sleep.
View Article and Find Full Text PDFObesity has dramatically increased in prevalence, making it essential to understand its accompanying metabolic changes. Modeling diet-induced obesity in Drosophila melanogaster (fruit flies), we elucidated transcriptional and metabolic changes in w (1118) flies on a high-fat diet (HFD). Mass spectrometry-based metabolomics revealed altered fatty acid, amino acid, and carbohydrate metabolism with HFD.
View Article and Find Full Text PDFA robust, bistable switch regulates the fluctuations between wakefulness and natural sleep as well as those between wakefulness and anesthetic-induced unresponsiveness. We previously provided experimental evidence for the existence of a behavioral barrier to transitions between these states of arousal, which we call neural inertia. Here we show that neural inertia is controlled by processes that contribute to sleep homeostasis and requires four genes involved in electrical excitability: Sh, sss, na and unc79.
View Article and Find Full Text PDFOne major unanswered question in neuroscience is how the brain transitions between conscious and unconscious states. General anesthetics offer a controllable means to study these transitions. Induction of anesthesia is commonly attributed to drug-induced global modulation of neuronal function, while emergence from anesthesia has been thought to occur passively, paralleling elimination of the anesthetic from its sites in the central nervous system (CNS).
View Article and Find Full Text PDFSleep is a whole-organism phenomenon accompanied by global changes in neural activity. We previously identified SLEEPLESS (SSS) as a glycosylphosphatidyl inositol-anchored protein required for sleep in Drosophila. Here we found that SSS is critical for regulating the sleep-modulating potassium channel Shaker.
View Article and Find Full Text PDFSleep is an essential process conserved from flies to humans. The importance of sleep is underscored by its tight homeostatic control. Through a forward genetic screen, we identified a gene, sleepless, required for sleep in Drosophila.
View Article and Find Full Text PDFStudy Objectives: In order to characterize the genetic mechanisms underlying sleep, we have carried out a large-scale screen in Drosophila to identify short-sleeping mutants. The objectives of this study were as follows: (1) characterize the phenotypes of the shortest-sleeping mutants; (2) examine whether changes in arousal threshold or sleep homeostasis underlie short-sleeping phenotypes; (3) clone a gene affected in one of the shortest sleepers; and (4) investigate whether circadian mutants can be identified using light:dark (L:D) locomotor data obtained for studying sleep behavior.
Design: Locomotor activity was measured using the Drosophila Activity Monitoring System in a 12:12 L:D cycle.
Sleep is one of the few major whole-organ phenomena for which no function and no underlying mechanism have been conclusively demonstrated. Sleep could result from global changes in the brain during wakefulness or it could be regulated by specific loci that recruit the rest of the brain into the electrical and metabolic states characteristic of sleep. Here we address this issue by exploiting the genetic tractability of the fruitfly, Drosophila melanogaster, which exhibits the hallmarks of vertebrate sleep.
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