Biology subjects

Emery, P.

Publications and source records attributed to Emery, P..

12 recordsLinked to original sources

bioRxiv2026

Membrane proteomics of the Drosophila circadian neural network

Circadian behaviors are controlled by dedicated brain pacemaker neurons, whose activity oscillate during the day and the night. The Drosophila brain contains ca. 240 such neurons. Their molecular clock is synchronized, but the phase of their rhythmic neural activity differs dramatically between functional groups. This explains how specific circadian neurons can for example promote morning or evening locomotor activity. To understand in depth how the circadian network functions, we surveyed its membrane proteome in the morning and evening, using in situ protein labeling and mass spectrometry. In addition to detecting known regulators of circadian behavior, we identified novel membrane or membrane-associated proteins present in circadian neurons. Through genetic screens, we found that many of these proteins regulate circadian behavior. In particular, Piezo regulates morning activity specifically under short photoperiod, and its loss compromises the structural plasticity of the clock neurons controlling locomotion at dawn. Our work thus illustrates the power of proteome-guided genetic screens to understand the mechanisms underlying circadian behavior.

neuroscience↗

bioRxiv2026

Diet-dependent sleep modulation by the Drosophila amino acid transporter ANIDRA

Sleep is a conserved animal behavior necessary for survival. It is under tight circadian and homeostatic control, and modulated by diet. Here, we identify the amino acid transporter ANIDRA (ANID) as an important sleep regulator in Drosophila. Flies lacking ANID show decreased and poorly consolidated daytime and nighttime sleep. Contrary to wild-type controls, anid mutant flies are unable to adjust their sleep to their diet, behaving as if they were constantly on a complete diet rich in amino acids. ANID is expressed in ensheathing and cortex glia, where it inhibits mTOR activity in a diet-dependent manner. Moreover, pharmacological inhibition of mTOR attenuates the anid mutant sleep phenotypes. Interestingly, DH44-expressing brain neurons, which promote arousal and sense amino acids, are constantly active in ANIDs absence. We therefore propose that ANID mediates detection of dietary amino acids by ensheathing and cortex glia to regulate the activity of arousal-promoting neurons.

neuroscience↗

bioRxiv2026

The CK2 and DBT kinases promote temperature compensation of the Drosophila circadian clock via distinct pathways

Circadian ([~]24 h) rhythms are essential for the survival of most organisms, as they optimize physiology and behavior with the time of day. They are defined by three fundamental properties: they are driven by a self-sustained molecular oscillator, entrained by environmental cues such as light and temperature, and temperature-compensated, whereby circadian period remains close to 24 h over a physiological range of temperatures. The molecular basis of temperature compensation remains incompletely understood. Here, we build on previous studies supporting a conserved and important role for phosphorylation-dependent mechanisms in the control of temperature compensation. We found that reducing the activity of two highly conserved circadian kinases, DBT (casein kinase [CK] 1) and CK2, disrupts temperature compensation in Drosophila. Genetic analyses indicate that DBT and CK2 act through distinct pathways that have additive effects on temperature compensation. DBT acts through the perShort phosphorylation cluster and the S47 phosphodegron of the core clock protein PER, both of which are required for normal thermal compensation. In contrast, CK2 acts through a phosphocluster in TIM as well as PER S45 residue. Interestingly, simultaneous disruption of both pathways causes accumulation of hyperphosphorylated PER, which is inefficiently cleared from the nucleus of circadian pacemaker neurons. Combined with previous work, our findings support a central and unifying role for nuclear PER phosphorylation dynamics in buffering circadian period against environmental temperature fluctuations.

neuroscience↗

bioRxiv2026

Core circadian clock genes control molecular and behavioral circatidal rhythms in Parhyale hawaiensis

Marine organisms exhibit 12.4-hour rhythms of gene expression, physiology and behavior synchronized by tidal cues. The mechanism underlying these circatidal rhythms, and its overlap with the circadian clockwork, has remained elusive. However, recent studies showed that the core circadian gene BMAL1 sustains circatidal behavior in crustaceans. Therefore, we mutagenized the other three core circadian clock genes (PhCry2, PhPer and PhClk) in P. hawaiensis, a marine amphipod. We found that they are necessary for both circadian and circatidal behaviors. Moreover, all four core circadian genes are critical for 24-h oscillations of mRNA levels in circadian brain neurons and 12.4-h mRNA rhythms in circatidal neurons. Unexpectedly, the mutants indicate that PhCLK represses PhPer expression independently of PhBMAL1 specifically in circatidal neurons. Our study thus reveals that circadian and circatidal clocks share four core molecular components, but their transcriptional wiring differs.

neuroscience↗

bioRxiv2025

miR-124 acts during Drosophila development to determine the phase of adult circadian behavior

Circadian behaviors need to be properly phased with the day/night cycle to be beneficial. We previously showed that the microRNA miR-124 regulates circadian behavior phase in Drosophila. Here, we report that miR-124 expression during larval development is required for proper phasing of both morning and evening peaks of activity in adults. Loss of miR-124 results in significant miswiring within the circadian neural network and severely alters neural activity rhythms in the ventral Lateral Neurons (s-LNvs) and the posterior Dorsal Neurons 1 (DN1ps), which control the timing of morning and evening activity. Silencing the s-LNvs in miR-124 mutant flies restores the phase of evening activity, while activating the DN1ps rescues the phases of both morning and evening activities. Our findings thus reveal the pivotal role of miR-124 in sculpting the circadian neural network during development and its long-lasting impact on circuit activity and adult circadian behavior.

neuroscience↗

bioRxiv2022

ATXN2 is a target of N-terminal proteolysis

Spinocerebellar ataxia 2 (SCA2) is a neurodegenerative disorder caused by the expansion of the poly-glutamine (polyQ) tract of Ataxin-2 (ATXN2). Other polyQ-containing proteins such as ATXN7 and huntingtin are associated with the development of neurodegenerative diseases when their N-terminal polyQ domains are expanded. Furthermore, they undergo proteolytic processing events that produce N-terminal fragments that include the polyQ stretch, which are implicated in pathogenesis. Interestingly, N-terminal ATXN2 fragments were reported in a brain extract from a SCA2 patient, but it is currently unknown whether an expanded polyQ domain contributes to ATXN2 proteolytic susceptibility. Here, we used transient expression in HEK293 cells to determine whether ATXN2 is a target for specific N-terminal proteolysis. We found that ATXN2 proteins with either normal or expanded polyQ stretches undergo proteolytic cleavage releasing an N-terminal polyQ-containing fragment. We identified a short amino acid sequence downstream of the polyQ domain that is necessary for N-terminal cleavage of full-length ATXN2 and sufficient to induce proteolysis of a heterologous protein. However, this sequence is not required for cleavage of a short ATXN2 isoform produced from an alternative start codon located just upstream of the CAG repeats encoding the polyQ domain. Our study extends our understanding of ATXN2 posttranslational regulation by revealing that this protein can be the target of specific proteolytic cleavage events releasing polyQ-containing products that are modulated by the N-terminal domain of ATXN2. N-terminal ATXN2 proteolysis of expanded polyQ domains might contribute to SCA2 pathology, as observed in other neurodegenerative disorders caused by polyQ domain expansion.

neuroscience↗

bioRxiv2021

PERIOD phosphoclusters control temperature compensation of the Drosophila circadian clock

Temperature compensation is a critical feature of circadian rhythms, but how it is achieved remains elusive. Here, we uncovered the important role played by the Drosophila PERIOD (PER) phosphodegron in temperature compensation. Using CRISPR-Cas9, we introduced a series of mutations that altered three Serines (S44, 45 and 47) belonging to the PER phosphodegron, the functional homolog of mammalian PER2s S487 phosphodegron, which impacts temperature compensation. While all three Serine to Alanine substitutions lengthened period at all temperatures tested, temperature compensation was differentially affected. S44A and S45A substitutions caused decreased temperature compensation, while S47A resulted in overcompensation. These results thus reveal unexpected functional heterogeneity of phosphodegron residues in thermal compensation. Furthermore, mutations impairing phosphorylation of the pers phosphocluster decreased thermal compensation, consistent with its inhibitory role on S47 phosphorylation. Interestingly, the S47A substitution caused increased accumulation of hyper-phosphorylated PER at warmer temperatures. This finding was corroborated by cell culture assays in which S47A resulted in excessive temperature compensation of phosphorylation-dependent PER degradation. Thus, we show a novel role of the PER phosphodegron in temperature compensation through temperature-dependent modulation of the abundance of hyper-phosphorylated PER. Our work also reveals interesting mechanistic convergences and differences between mammalian and Drosophila temperature compensation of the circadian clock. Author summaryCircadian rhythms are critical adaptive mechanisms that enable most organisms to adjust their physiology and behavior to the changes that occur in their environment every day. Ambient temperature varies constantly, but interestingly molecular circadian pacemakers do not accelerate with increasing temperature, while most biochemical reactions are sensitive to temperature. This phenomenon of circadian temperature compensation is poorly understood. Using genome editing and transgenic approaches, we found that two phosphorylated motifs in the Drosophila PERIOD protein, which regulate stability, impact temperature compensation. Moreover, we observed that mutation of a key Serine residue controlling PER degradation, S47, affects the accumulation of phosphorylated PER in a temperature-dependent manner, and causes PER degradation kinetics to become overly protected from increased temperature. As a result, the circadian clock of S47 mutant flies is excessively temperature-compensated. Our work thus reveals an interesting mechanism that controls temperature compensation in Drosophila. Moreover, comparison with mammals reveal interesting similarities, but also important differences in how temperature compensation of the circadian clock is achieved.

genetics↗

bioRxiv2021

Astrocytic GABA Transporter controls sleep by modulating GABAergic signaling in Drosophila circadian neurons

A precise balance between sleep and wakefulness is essential to sustain a good quality of life and optimal brain function. GABA is known to play a key and conserved role in sleep control, and GABAergic tone should therefore be tightly controlled in sleep circuits. Here we examined the role of the astrocytic GABA transporter (GAT) in sleep regulation using Drosophila melanogaster. We found that a hypomorphic gat mutation (gat33-1) increased sleep amount, decreased sleep latency, and increased sleep consolidation. Interestingly, sleep defects were suppressed when gat33-1 was combined with a mutation disrupting wide-awake (wake), a gene that regulates the cell-surface levels of the GABAA receptor Resistance to Dieldrin (RDL) in the wake-promoting large ventral lateral neurons (l-LNvs). Moreover, RNAi knockdown of rdl and its modulator dnlg4 in these circadian neurons also suppressed gat33-1 sleep phenotypes. Brain immunohistochemistry showed that GAT-expressing astrocytes were located near RDL-positive l-LNvs cell bodies and dendritic processes. We conclude that astrocytic GAT decreases GABAergic tone and RDL activation in arousal promoting LNvs, thus determining proper sleep amount and quality in Drosophila

neuroscience↗

bioRxiv2021

Dopaminergic Ric GTPase activity impacts amphetamine sensitivity and sleep quality in a dopamine transporter-dependent manner in Drosophila melanogaster

Dopamine (DA) is required for movement, sleep, and reward, and DA signaling is tightly controlled by the presynaptic DA transporter (DAT). Therapeutic and addictive psychostimulants, including methylphenidate (Ritalin; MPH), cocaine, and amphetamine (AMPH), markedly elevate extracellular DA via their actions as competitive DAT inhibitors (MPH, cocaine) and substrates (AMPH). DAT silencing in mice and invertebrates results in hyperactivity, reduced sleep, and blunted psychostimulant responses, highlighting DATs essential role in DA-dependent behaviors. DAT surface expression is not static; rather it is dynamically regulated by endocytic trafficking. PKC-stimulated DAT endocytosis requires the neuronal GTPase, Rit2, and Rit2 silencing in mouse DA neurons impacts psychostimulant sensitivity. However, it is unknown whether or not Rit2-mediated changes in psychostimulant sensitivity are DAT-dependent. Here, we leveraged Drosophila melanogaster to test whether the Drosophila Rit2 ortholog, Ric, impacts dDAT function, trafficking, and DA-dependent behaviors. Orthologous to hDAT and Rit2, dDAT and Ric directly interact, and the constitutively active Ric mutant Q117L increased dDAT surface levels and function in cell lines and ex vivo Drosophila brains. Moreover, DAergic RicQ117L expression caused sleep fragmentation in a DAT-dependent manner but had no effect on total sleep and daily locomotor activity. Importantly, we found that Rit2 is required for AMPH-stimulated DAT internalization in mouse striatum, and that DAergic RicQ117L expression significantly increased Drosophila AMPH sensitivity in a DAT-dependent manner, suggesting a conserved impact of Ric-dependent DAT trafficking on AMPH sensitivity. These studies support that the DAT/Rit2 interaction impacts both baseline behaviors and AMPH sensitivity, potentially by regulating DAT trafficking.

neuroscience↗

bioRxiv2019

B cell tetherin: a flow-cytometric cell-specific assay for response to Type-I interferon predicts clinical features and flares in SLE

ObjectiveType I interferon (IFN-I) responses are broadly associated with autoimmune disease including SLE. Given the cardinal role of autoantibodies in SLE, we investigated whether a B lineage cell-specific IFN assay might correlate with SLE activity. MethodsB cells and PBMCs were stimulated with IFN-I and IFN-II. Gene expression was scrutinised for pathway-related membrane protein expression. A flow-cytometric assay for tetherin (CD317), an IFN-induced protein ubiquitously expressed on leucocytes, was validated in vitro then clinically against SLE diagnosis, plasmablast expansion, and BILAG-2004 score in a discovery cohort (156 SLE; 30 RA; 22 healthy controls). A second longitudinal validation cohort of 80 patients was also evaluated for SLE flare prediction. ResultsIn vitro, a close cell-specific and dose-responsive relationship between IFN-I responsive genes and cell surface tetherin in all immune subsets existed. Tetherin expression was selectively responsive to the IFN-I compared to IFN-II and -III. In the discovery cohort memory B-cell tetherin was best associated with diagnosis (SLE/HC: effect size=0.11, p=0.003;SLE/RA: effect size=0.17, p<0.001); plasmablast numbers in rituximab-treated patients (Rho=0.38, p=0.047) and BILAG-2004. Association were equivalent or stronger than interferon score or monocyte tetherin. The validation cohort confirmed this relationship with memory B-cell tetherin predictive of future clinical flares (Hazard Ratio=2.29 (1.01-4.64), p=0.022). ConclusionMemory B cell surface tetherin, a reflection of cell-specific IFN response in a convenient flow cytometric assay, was associated with SLE diagnosis, disease activity and predicted flares better than other cell subsets or whole blood assays in independent validation cohorts.

immunology↗

bioRxiv2018

PSI controls tim splicing and circadian period in Drosophila

The Drosophila circadian pacemaker consists of transcriptional feedback loops subjected to both post-transcriptional and post-translational regulation. While post-translational regulatory mechanisms have been studied in detail, much less is known about circadian post-transcriptional control. To have a better understanding of the role and mechanisms of circadian post-transcriptional regulation, we targeted 364 RNA binding and RNA associated proteins with RNA interference. Among the 43 genes we identified was the alternative splicing regulator P-element somatic inhibitor (PSI). PSI downregulation shortens the period of circadian rhythms both in the brain and in peripheral tissues. Interestingly, we found that PSI regulates the thermosensitive alternative splicing of timeless (tim), promoting splicing events favored at warm temperature over those increased at cold temperature. Moreover, the period of circadian behavior was insensitive to PSI downregulation when flies could produce functional TIM proteins only from a transgene that cannot form the thermosensitive splicing isoforms. Therefore, we conclude that PSI regulates the period of Drosophila circadian rhythms through its modulation of the tim splicing pattern.

neuroscience↗

bioRxiv2018

Plasmacytoid dendritic cells are functionally exhausted while non-haematopoietic sources of type I interferon dominate human autoimmunity

Autoimmune connective tissue diseases arise in a stepwise fashion from asymptomatic preclinical autoimmunity. Type I interferons (IFNs) have a crucial role in the progression to established autoimmune diseases such as systemic lupus erythematosus (SLE). However, their cellular source and regulation in disease initiation are unclear. The current paradigm suggests that plasmacytoid dendritic cells (pDCs) are activated in SLE contributing to excessive IFN production. Here, we show that in preclinical autoimmunity, established SLE, and primary Sjogrens Syndrome, pDCs are not effector cells, but rather have lost their capacity for TLR-mediated IFN- and TNF production and fail to induce T cell activation, independently of disease activity and blood IFN signature. In addition, pDCs present a transcriptional signature of cellular stress and senescence accompanied by increased telomere erosion. Instead, we demonstrate a marked enrichment of IFN signature in non-lesional skin in preclinical autoimmunity. In these individuals and SLE patients, type I IFNs were abundantly produced by keratinocytes in the absence of infiltrating leucocytes. These findings revise our understanding of the role of IFN in the initiation of human autoimmunity, with non-haematopoietic tissues perpetuating IFN responses, which in turn predict clinical disease. These data indicate potential therapeutic targets outside the conventional immune system for treatment and prevention.

immunology↗