Biology subjects

Musiek, E. S.

Publications and source records attributed to Musiek, E. S..

13 recordsLinked to original sources

bioRxiv2026

Tumbly: An Open-Source Home-Cage Device for Time-Restricted Feeding in Mice

Time-restricted feeding (TRF) is a common tool for studying metabolism, circadian rhythms, aging, and neurodegeneration. Here, we describe a new device called Tumbly, an automated device for performing TRF studies in mouse home-cages. Tumbly controls access to rodent diets at user-set times via a programmable servo-driven food hopper. Tumbly is also battery powered and compatible with multiple types of vivarium home-cages, due to a removable faceplate that can be customized to fit different cage dimensions without modification. Finally, Tumbly is open-source and affordable, with all design files available online, allowing researchers to build and customize it. As a validation test, we deployed Tumbly in two labs at separate institutions, one with singly housed mice (n = 6, within-subject) and one with group-housed mice (n = 22, between-group). We measured daily body weight and food intake. In both labs, mice on an 8-hour TRF schedule maintained their body weight and ate similar amounts of food compared to ad libitum feeding. Our quantified error rates were also low, with no device failures over >1000 hours of operation. We conclude that Tumbly provides a reliable, low-cost option for running TRF studies in mice.

neuroscience↗

bioRxiv2026

Complement component C4 regulates amyloid pathology and glial reactivity in mouse model of Alzheimer's Disease

The complement system, a proteolytic cascade crucial for innate immune system function, is dysregulated in brain aging and neurodegenerative diseases, including Alzheimer Disease (AD). In models of AD, complement proteins, including C1q and C3, are upregulated and mediate microglial clearance of amyloid plaques and pruning of synapses. Among complement genes, C4b, which in mice encodes complement protein C4, is the most highly upregulated in astrocytes in the setting of aging and amyloid pathology. While C4 plays a key role in the complement cascade, there have been no investigations of the direct role of C4 in regulating AD pathology. To probe the function of C4 in amyloid plaque-related pathology, we crossed a germ line C4b knockout mouse (C4 KO) to the 5XFAD mouse model of AD-related amyloidosis. To our surprise, we observed striking reductions in amyloid plaque pathology across multiple brain regions in 5XFAD-C4 KO mice relative to standard 5XFAD controls. This reduction in plaque burden stands in sharp contrast to previous reports of C3 deletion in AD models, which increases plaques. Additionally, we observed a reduction in neuroinflammation and peri-plaque glial clustering in 5XFAD-C4 KO mice, suggestive of a role for C4 in regulating overall neuroinflammatory tone in AD. Finally, we observed a phenotypic shift of the peri-plaque microglia to a more reactive disease-associated microglia (DAM) phenotype, indicating that C4 could be an important factor in regulating microglial reactivity in AD. Altogether, our results demonstrate that C4 may have functions beyond the classical complement cascade and may serve as a key facilitator of AD-related glial function and pathology and a possible target for therapeutic modification.

neuroscience↗

bioRxiv2026

In vivo BMAL1 occupancy mapping using MACS-Calling Cards reveals disease-associated retargeting in Cln3Δex7/8 astrocytes

Astrocytic homeostatic programs, many of which are regulated by the circadian clock, are disrupted early in neurodegenerative disease. The core clock transcription factor (TF) BMAL1 is required for normal astrocyte function, but its role during disease remains unclear. This is partly because methods for identifying cell type-specific TF binding sites are limited. Here, we developed MACS-Calling Cards (MACS-CC), a strategy for mapping astrocyte-specific TF occupancy in vivo. We used MACS-CC to define BMAL1 binding in the Cln3{Delta}ex7/8 mouse model of CLN3 disease, a fatal neurodegenerative disorder marked by early astrocyte dysfunction and circadian disruption. BMAL1 binding was extensively redistributed in Cln3{Delta}ex7/8 astrocytes: wild-type-specific binding sites enriched near glial differentiation genes, whereas Cln3{Delta}ex7/8-specific sites lacked functional enrichment. Consistent with these changes, Cln3{Delta}ex7/8 astrocytes decreased expression of mature astrocyte markers. To define mechanisms underlying BMAL1 retargeting, we tested whether altered chromatin accessibility explained the changes in BMAL1 binding. Although chromatin accessibility was broadly remodeled, differential accessibility did not predict BMAL1 redistribution. Instead, motif analysis suggested that loss of cooperative TF interactions drives BMAL1 retargeting. These findings demonstrate that MACS-CC enables astrocyte-specific TF occupancy mapping and reveals mechanisms behind early rewiring of circadian regulatory programs within a model of a neurodegenerative disease. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/721783v2_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@1ada239org.highwire.dtl.DTLVardef@7564a3org.highwire.dtl.DTLVardef@122222forg.highwire.dtl.DTLVardef@1f2729c_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2026

The astrocyte clock controls circadian perineuronal net remodeling, synapse strength and learning behavior

The circadian clock controls a vast array of cellular and organismal functions, from the molecular scale to behavior. While each cell is regimented by a cell-autonomous clock, few studies in the brain have dissected the circuit and behavioral contributions of cell-specific clocks. Relatedly, astrocytes are now known to play key roles in regulating synaptic function, circuit activity and behavior, but whether these functions are guided by astrocyte-autonomous clocks is unknown. Here, we report that post-natal deletion of the critical circadian clock gene Bmal1 in astrocytes, which abrogates core clock function in a cell type specific manner, induced expression of genes related to extracellular matrix (ECM) production, maintenance, and remodeling. Circadian variations have been shown in a specific ECM structure, perineuronal nets (PNNs), which are implicated in synaptic function and plasticity. In astrocyte-specific Bmal1 knockouts, hippocampal PNN abundance was decreased, and the circadian rhythm of these structures was also abolished. In line with evidence implicating PNNs, and the ECM in general, in synaptic function and plasticity, we found that astrocyte-specific Bmal1 KO mice had increased synaptic strength but blunted long term potentiation (LTP), as well as impaired learning and memory performance in a novel object recognition task. Taken together, these findings suggest that the astrocyte circadian clock regulates circadian rhythms in perineuronal net abundance as well as synaptic plasticity and behavioral learning and memory.

neuroscience↗

bioRxiv2025

Circadian rhythms and the light-dark cycle interact to regulate amyloid plaque accumulation and tau phosphorylation in 5xFAD mice

BackgroundCircadian disruption has long been appreciated as a downstream consequence of Alzheimers Disease in humans. However, an upstream role for behavioral circadian disruption in regulating AD pathology remains an open question. MethodsTo determine the role of the central circadian clock in the suprachiasmatic nucleus (SCN) in regulating amyloid pathology, we generated mice harboring deletion of the critical clock gene Bmal1 in GABAergic neurons using VGAT-iCre, which is expressed in >95% of SCN cells, and crossed this line to the 5xFAD amyloid mouse model. To examine the role of the light-dark cycle in this process, we aged these mice in either regular 12:12 light-dark (LD) or constant darkness (DD) conditions. Transcriptional, behavioral, and physiological rhythms were examined in VGAT-iCre; Bmal1fl/fl; 5xFAD (VGAT-BMAL1KO;5xFAD) mice under varying light conditions. Amyloid plaque deposition, peri-plaque tau phosphorylation, glial activation, and transcriptomic changes were examined. ResultsVGAT-BMAL1KO;5xFAD mice showed loss of SCN BMAL1 expression and severe disruption of behavioral rhythms in both LD and DD, with loss of day-night rhythms in consolidated sleep and blunting of rhythmic clock gene expression in the brain. Surprisingly, VGAT-BMAL1KO;5xFAD mice kept under LD showed reduced total plaque accumulation and peri-plaque tau phosphorylation, compared to Cre-negative controls. These changes were gated by the light-dark cycle, as they were absent in VGAT-BMAL1KO;5xFAD mice kept in DD conditions. Total plaque accumulation was also reduced in control 5xFAD mice kept in DD as compared to LD, suggesting a general effect of light-dark cycle on amyloid aggregation. Expression of murine presenilin 1 (Psen1), as well as amyloidogenic cleavage of amyloid precursor protein, were suppressed in VGAT-BMAL1KO;5xFAD specifically under LD conditions. ConclusionsIn 5xFAD mice, the central circadian clock and the light-dark cycle interact to regulate amyloid pathology. Disruption of the central clock in the presence of a light-dark cycle may reduce APP cleavage and plaque formation. These results call into question the proposed simple positive feedback loop between circadian rhythm disruption and Alzheimers Disease pathology.

neuroscience↗

bioRxiv2025

Ms4a4a deficiency ameliorates plaque pathology in a mouse model of amyloid accumulation

Genome-wide association studies for Alzheimer disease (AD) risk have identified a number of genes enriched in microglia, including MS4A4A. Common variants in MS4A4A influence AD risk, MS4A4A expression, TREM2 signaling, and a specific microglial transcriptional state, though the exact role of MS4A4A in AD remains unclear. Using a mouse model of amyloid beta (A{beta}) accumulation (5xFAD), we examined the impact of Ms4a4a loss on A{beta} pathology. Before A{beta} accumulation, Ms4a4a loss reduces steady-state A{beta} levels and shortens A{beta} half-life in brain interstitial fluid. In aged 5xFAD Ms4a4a-deficient mice, plaques are more compact with reduced overall plaque burden. Microglia lacking Ms4a4a are more pro-inflammatory and produce more MMP-9, which may promote degradation of A{beta} and A{beta} fibrils. Human subjects that carry a variant near MS4A4A (rs1582763) that confers resilience to AD also exhibit significantly elevated levels of MMP-9 in their cerebrospinal fluid. Together, our results suggest that loss of Ms4a4a improves A{beta} pathology by altering A{beta} clearance, offering insights for therapeutic interventions in AD.

neuroscience↗

bioRxiv2025

Reconstructed Cell-Type Specific Rhythms in Human Brain link Alzheimer's Pathology, Circadian Stress, and Ribosomal Disruption

Alzheimers disease (AD) disrupts behavioral circadian rhythms, but its effects on molecular rhythms in the human brain are poorly understood. Using single-nucleus RNA sequencing from post-mortem cortical samples, we informatically estimated the relative circadian phases of 409 persons with and without AD dementia. We then reconstructed circadian expression profiles across cell types. While core clock rhythms were preserved in AD, many cell-type specific circadian outputs were disrupted. Rhythms in ribosomal biogenesis and oxidative phosphorylation were dampened across cell types. Similar losses in ribosomal gene expression rhythms were observed in APP/PS1 mice, which showed further reductions in ribosomal protein expression and polysome-mediated translation after circadian desynchrony. Exploratory computational modeling reveals that altered translation may contribute to the increased circadian variability seen in AD patients. These findings reveal altered cell-type specific circadian output rhythms in the brains of AD affected patients, and highlight disrupted ribosomal rhythms as a feature of AD.

bioinformatics↗

bioRxiv2024

Inflammatory pain in mice induces light cycle-dependent effects on sleep architecture

As a syndrome, chronic pain comprises physical, emotional, and cognitive symptoms such as disability, negative affect, feelings of stress, and fatigue. A rodent model of long-term inflammatory pain, induced by complete Freunds adjuvant (CFA) injection, has previously been shown to cause anhedonia and dysregulated naturalistic behaviors, in a manner similar to animal models of stress. We examined whether this extended to alterations in circadian rhythms and sleep, such as those induced by chronic social defeat stress, using actigraphy and wireless EEG. CFA-induced inflammatory pain profoundly altered sleep architecture in male and female mice. Injection of the hind paw, whether with CFA or saline, reduced some measures of circadian rhythmicity such as variance, period, and amplitude. CFA increased sleep duration primarily in the dark phase, while sleep bout length was decreased in the light and increased in the dark phase. Additionally, CFA reduced wake bout length, especially during the dark phase. Increases in REM and SWS duration and bouts were most significant in the dark phase, regardless of whether CFA had been injected at its onset or 12 hours prior. Taken together, these results indicate that inflammatory pain acutely promotes but also fragments sleep.

neuroscience↗

bioRxiv2024

A glial circadian gene expression atlas reveals cell type and disease-specific reprogramming in response to amyloid pathology or aging.

While circadian rhythm disruption may promote neurodegenerative disease, how aging and neurodegenerative pathology impact circadian gene expression patterns in different brain cell types is unknown. Here, we used translating ribosome affinity purification methods to define the circadian translatomes of astrocytes, microglia, and bulk cerebral cortex, in healthy mouse brain and in the settings of amyloid-beta plaque pathology or aging. Our data reveal that glial circadian translatomes are highly cell type-specific and exhibit profound, context-dependent reprogramming of rhythmic transcripts in response to amyloid pathology or aging. Transcripts involved in glial activation, immunometabolism, and proteostasis, as well as nearly half of all Alzheimer Disease (AD)-associated risk genes, displayed circadian oscillations, many of which were altered by pathology. Amyloid-related differential gene expression was also dependent on time of day. Thus, circadian rhythms in gene expression are cell- and context dependent and provide important insights into glial gene regulation in health, AD, and aging.

neuroscience↗

bioRxiv2024

Microglia drive diurnal variation in susceptibility to inflammatory blood-brain barrier breakdown

The blood-brain barrier (BBB) is critical for maintaining brain homeostasis but is susceptible to inflammatory dysfunction. Permeability of the BBB to lipophilic molecules shows circadian variation due to rhythmic transporter expression, while basal permeability to polar molecules is non-rhythmic. Whether daily timing influences BBB permeability in response to inflammation is unknown. Here, we induced systemic inflammation through repeated lipopolysaccharide (LPS) injections either in the morning (ZT1) or evening (ZT13) under standard lighting conditions, then examined BBB permeability to a polar molecule, sodium fluorescein. We observed clear diurnal variation in inflammatory BBB permeability, with a striking increase in paracellular leak across the BBB specifically following evening LPS injection. Evening LPS led to persisting glia activation and inflammation in the brain that was not observed in the periphery. The exaggerated evening neuroinflammation and BBB disruption were suppressed by microglial depletion or through keeping mice in constant darkness. Our data show that diurnal rhythms in microglial inflammatory responses to LPS drive daily variability in BBB breakdown and reveals time-of-day as a key regulator of inflammatory BBB disruption.

neuroscience↗

bioRxiv2024

Kir6.2-KATP channels alter glycolytic flux to modulate cortical activity, arousal, and sleep-wake homeostasis

Metabolism plays an important role in the maintenance of vigilance states (e.g. wake, NREM, and REM). Brain lactate fluctuations are a biomarker of sleep. Increased interstitial fluid (ISF) lactate levels are necessary for arousal and wake-associated behaviors, while decreased ISF lactate is required for sleep. ATP-sensitive potassium (KATP) channels couple glucose-lactate metabolism with neuronal excitability. Therefore, we explored how deletion of neuronal KATP channel activity (Kir6.2-/- mice) affected the relationship between glycolytic flux, neuronal activity, and sleep/wake homeostasis. Kir6.2-/- mice shunt glucose towards glycolysis, reduce neurotransmitter synthesis, dampen cortical EEG activity, and decrease arousal. Kir6.2-/- mice spent more time awake at the onset of the light period due to altered ISF lactate dynamics. Together, we show that Kir6.2-KATP channels act as metabolic sensors to gate arousal by maintaining the metabolic stability of each vigilance state and providing the metabolic flexibility to transition between states. HighlightsO_LIGlycolytic flux is necessary for neurotransmitter synthesis. In its absence, neuronal activity is compromised causing changes in arousal and vigilance states despite sufficient energy availability. C_LIO_LIWith Kir6.2-KATP channel deficiency, the ability to both maintain and shift between different vigilance states is compromised due to changes in glucose utilization. C_LIO_LIKir6.2-KATP channels are metabolic sensors under circadian control that gate arousal and sleep/wake transitions. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=153 SRC="FIGDIR/small/581817v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@11640c6org.highwire.dtl.DTLVardef@1f6a88corg.highwire.dtl.DTLVardef@b38daborg.highwire.dtl.DTLVardef@1a061f_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2020

REV-ERBalpha mediates complement expression and circadian regulation of microglial synaptic phagocytosis

The circadian clock has been shown to regulate various aspects of brain health including microglial and astrocyte activation. Here we report that deletion of the master clock protein BMAL1 induces robust increases in the expression of complement genes such as C3, C4b and C1q in the hippocampus. Loss of downstream REV-ERB-mediated transcriptional repression led to increases in C4b in neurons and astrocytes as well as C3 protein in microglia and astrocytes. REV-ERB deletion induced complement C3/C4b gene expression and increased microglial phagocytosis of synapses in the CA3 region of the hippocampus. Finally, we observed diurnal variation in the degree of microglial synaptic phagocytosis in wild type mice which was abrogated by REV-ERB deletion. This work uncovers the BMAL1-REV-ERB axis as a regulator of complement expression and synaptic phagocytosis in the brain, thereby illuminating a novel mechanism of synaptic regulation by the circadian clock.

neuroscience↗

bioRxiv2018

Cell-autonomous regulation of astrocyte activation by the circadian clock protein BMAL1

Circadian clock dysfunction is a common symptom of aging and neurodegenerative diseases, though its impact on brain health is poorly understood. Astrocyte activation occurs in response to diverse insults, and plays a critical role in brain health and disease. We report that the core clock protein BMAL1 regulates astrogliosis in a synergistic manner via a cell-autonomous mechanism, and via a lesser non-cell-autonomous signal from neurons. Astrocyte-specific Bmal1 deletion induces astrocyte activation in vitro and in vivo, mediated in part by suppression of glutathione-s-transferase signaling. Functionally, loss of Bmal1 in astrocytes promotes neuronal death in vitro. Our results demonstrate that the core clock protein BMAL1 regulates astrocyte activation and function in vivo, elucidating a novel mechanism by which the circadian clock could influence many aspects of brain function and neurologic disease.

neuroscience↗