Biology subjects

Herzog, E.

Publications and source records attributed to Herzog, E..

At least 19 recordsLinked to original sources

bioRxiv2026

Circadian Clock Gene Modulation and Selective Reprogramming in Response to Virus Infection

The circadian clock regulates fundamental cellular processes that include the host response to infection. However, the intersection of the circadian clock and the mechanisms that drive antiviral immunity remains poorly understood. Copy-back viral genomes (cbVGs) generated during virus replication strongly stimulate immunity during infection with negative-sense RNA viruses. Here, we demonstrate at the single cell level that A549 lung epithelial cells, commonly used to model lung infections, sustain circadian rhythms and upon infection with Sendai virus (SeV) progressively remodel the circadian clock through an innate immune response driven primarily by cbVGs. Furthermore, we show that cbVG-driven changes in circadian gene expression are mediated through two distinct innate immune sensing pathways: the RIG-I adaptor MAVS is required for preferential induction of the BMAL1 paralog ARNTL2, whereas the double-stranded RNA sensor PKR is required for the cbVG-specific induction of the negative-feedback regulators NR1D1, NR1D2, and PER1. A similar cbVG-specific signature was observed during respiratory syncytial virus infection, suggesting that cbVG-driven circadian gene regulation is not unique to SeV. In addition, we established through gain- and loss-of-function experiments that ARNTL2 is functionally required for amplifying the transcriptional response to infection, with selective effects on the expression of specific antiviral genes, including CCL5. Together, these findings establish innate immune signaling triggered by cbVGs as selective driver of circadian clock gene expression during viral infection through distinct sensing pathways and identify ARNTL2 as a previously unrecognized regulator of virus-induced host transcriptional responses.

microbiology↗

bioRxiv2026

High-throughput stomatal phenotyping provides selection targets for stress-resilient wheat

Phenotyping stomatal traits and their developmental plasticity is time-consuming but holds potential to improve water use efficiency and photosynthesis for designing stress-tolerant crops under climate change. Here, we develop a robust, high-throughput pipeline for phenotyping 14 stomatal traits in winter wheat related to size, variation, maximum conductance, and spatial patterning. We (1) analyze over 25,000 images from 60 wheat cultivars grown in growth chamber, greenhouse, and field conditions; (2) investigate the impact of light, temperature, and reduced water and nitrogen supply on stomatal traits and their developmental plasticity across adaxial and abaxial surfaces; and (3) evaluate genetic diversity and breeding progress of stomatal traits. Stomatal traits were highly broad-sense heritable, were largely plastic in response to environmental conditions, and showed genotype-specific responses. Stomatal traits of third leaves under controlled environments with stable light and temperature conditions reliably captured the genetic variance of flag leaves under field conditions. Our data suggests that the upper leaf surface contributed more to transpiration and cooling through consistently higher stomatal density, area, and maximum conductance, while the lower surface facilitated CO2 diffusion via systematic proper patterning and spacing. Breeding maintains the genetic diversity of stomatal traits, and our pipeline facilitates breeders to target them to enhance water use efficiency in high-yielding modern cultivars.

plant biology↗

bioRxiv2025

Fetoplacental circadian rhythms develop and then synchronize to the mother in utero

Circadian rhythms in gene expression and hormones are ubiquitous across species and differentiated cell types, yet their developmental origins remain poorly understood. This study aimed to determine if daily rhythms can be detected in utero and if they synchronize to the mother. We developed methods to longitudinally monitor PERIOD2 (PER2), a core circadian clock protein, from embryonic day (E)8.5 to E17.5 by restricting PER2::LUCIFERASE (PER2::LUC) expression to the mouse fetoplacental unit (fetus and fetal-derived tissues). In utero fetoplacental bioluminescence imaging showed that PER2 levels rose exponentially during pregnancy, with variable daily peak times that stabilized to dusk by E15.5. Interestingly, pregnancies that did not exhibit daily in utero PER2 variation were more likely to fail. Because maternal glucocorticoids have been implicated in fetal development and synchronizing other circadian tissues, we tested its capability to shift fetoplacental PER2 rhythms in utero. Daily subcutaneous glucocorticoid injections over five days of late pregnancy phase-dependently shifted the fetoplacental PER2 rhythms in utero. Blocking glucocorticoid signaling in vitro reduced synchrony between maternal and fetal placenta by [~]40%. We conclude that in utero daily rhythms gradually develop and synchronize with the mother prior to birth, potentially through glucocorticoid signaling.

developmental biology↗

bioRxiv2025

A Data-Driven Closed-Loop Control Approach to Drive NeuralState Transitions for Mechanistic Insight

Repetitive negative thinking (RNT) is a transdiagnostic risk factor for mood disorders, consistently associated with altered biological substrates, including functional connectivity in key brain networks. As a stable cognitive feature linked to vulnerability across disorders, RNT presents a compelling target for intervention. However, leveraging RNT as a modifiable mechanism requires a deeper understanding of its causal neural dynamics and how targeted modulation can induce adaptive change. We introduce a data-driven framework that combines dynamical system reconstruction (DSR) with model predictive control (MPC) to infer optimal control policies for transitions between resting and sad mood brain states from functional magnetic resonance imaging (fMRI) data. Using nonlinear generative DSR models trained on individuals with remitted major depressive disorder (rMDD) and matched healthy controls (HCs), we derive region-specific, state-dependent control strategies. We find that small brain regions (e.g., sgACC, NAcc) exhibit higher controllability, requiring less energy to drive state transitions. Critically, rMDD participants require less control energy than HCs to move into sad mood from rest and - unexpectedly - also to move back to rest, though the latter effect is spatially restricted. Despite comparable target attainment, rMDD participants remain closer to the sad mood distribution when returning to rest, indicating a residual negative-affect bias. Our data-driven analysis reveals elevated effective coupling in rMDD, most prominently toward (but not away from) the DLPFC. Across regions, greater coupling is associated with reduced control energy, suggesting that enhanced network influence facilitates more efficient state transitions. These results suggest dynamics in rMDD that facilitate entry into negative affect and hinders full disengagement without sustained input, highlighting closed-loop control as a tool for mechanistic insight and potentially for designing targeted neuromodulatory interventions in the future.

neuroscience↗

bioRxiv2025

Competing Programs Shape Cortical Sensorimotor-Association Axis Development

The neocortex is organized along a dominant sensorimotor-to-association (S-A) axis, anchored by modality-specific primary sensorimotor areas at one end and transmodal association areas that form distributed networks supporting abstract cognition at the other. The developmental mechanisms shaping this axis remain elusive. Here, we present converging multispecies evidence supporting the Multinodal Induction-Exclusion in Network Development (MIND) model, in which S-A patterning is governed by competing processes of induction and exclusion, driven by opposing transcriptomically-defined identity programs emerging from different nodes. Key molecular and connectional features of association cortices arise through pericentral programs, originating around fronto-temporal poles and partially regulated by retinoic acid. They progress inward toward central territories of the naive neocortex along fronto-temporally polarized trajectories. Central programs are induced through interactions between topographically separated first-order sensorimotor thalamocortical inputs and the neocortex, promoting the formation of primary areas while excluding pericentral programs. Influenced by SATB2 and ZBTB18, these evolutionarily conserved programs compete for the same territory and create spatial compartmentalization of axon guidance, cell-cell adhesion, retinoic acid signaling, synaptogenesis, Wnt signaling, and autism risk genes. Notably, PLXNC1 and SEMA7A exhibit anti-correlated expression and repulsive functions in shaping cortico-cortical connectivity along the S-A axis. These processes of induction and exclusion establish an S-A equilibrium and topography in which primary sensorimotor areas emerge as focal islands within the broader ocean of distributed associative networks. The MIND model provides a unifying framework for understanding experimental, evolutionary, and clinical phenomena, revealing induction and exclusion as antagonistic complementary principles shaping the S-A axis and processing hierarchies.

neuroscience↗

bioRxiv2025

Root hair growth phases are coordinated by cytoskeleton, nucleus dynamics and cell mechanics in Arabidopsis

Polar cell growth is a fundamental process across organisms, yet its coordination with nuclear movement and cytoskeleton dynamics remains underexplored. Focusing on Arabidopsis thaliana root hairs, we investigate these processes using high-resolution live imaging within microfluidics-based experiments. By incorporating data on cytoskeletal dynamics, nuclear positioning, and tip growth into a mathematical model, we analyse how their interactions shape the different growth phases that we reveal for the first time in this study. Chemical treatments and mutant analyses further support our model, revealing that timely cytoskeletal changes drive transitions between these growth phases, and correlate with shifts in nuclear movement and morphology. This regulation suggests a microtubule-actin crosstalk in the root hair subapical region. Additionally, we present novel findings on vacuole movement and cell stiffness, further refining our understanding of tip growth dynamics. Collectively, our work provides a comprehensive framework for understanding how transitions between growth phases are orchestrated in plant tip-growing cells.

cell biology↗

bioRxiv2025

Dual-responsive synthetic gene circuit for dynamic biologic drug delivery via inflammatory and circadian signaling pathways

BackgroundEngineered cells provide versatile tools for precise, tunable drug delivery, especially when synthetic stimulus-responsive gene circuits are incorporated. In many complex disease conditions, endogenous pathologic signals such as inflammation can vary dynamically over different time scales. For example, in autoimmune conditions such as rheumatoid arthritis or juvenile idiopathic arthritis, local (joint) and systemic inflammatory signals fluctuate daily, peaking in the early morning, but can also persist over long periods of time, triggering flare-ups that can last weeks to months. However, treatment with disease-modifying anti-rheumatic drugs is typically provided at continuous high doses, regardless of disease activity and without consideration for levels of inflammatory signals. In previous studies, we have developed cell-based drug delivery systems that can automatically address the different scales of flares using either chronogenetic circuits (i.e., clock gene-responsive elements) that can be tuned for optimal drug delivery to dampen circadian variations in inflammatory levels or inflammation-responsive circuits (i.e., NF-{kappa}B-sensitive elements) that can respond to sustained arthritis flares on demand with proportional synthesis of drug. The goal of this study was to develop a novel dual-responsive synthetic gene circuit that responds to both circadian and inflammatory inputs using OR-gate logic for both daily timed therapeutic output and enhanced therapeutic output during chronic inflammatory conditions. ResultsWe developed a synthetic gene circuit driven by tandem inflammatory NF-{kappa}B and circadian E-box response elements. When engineered into induced pluripotent stem cells that were chondrogenically differentiated, the gene circuit demonstrated basal-level circadian output with enhanced stimulus-responsive output during an inflammatory challenge shown by bioluminescence monitoring. Similarly, this system exhibited enhanced therapeutic levels of biologic drug interleukin-1 receptor antagonist (IL-1Ra) during an inflammatory challenge in differentiated cartilage pellets. This dual-responsive therapeutic gene circuit mitigated both the inflammatory response as measured by bioluminescence reporter output and tissue-level degradation during conditions mimicking an arthritic flare. ConclusionsThe dual-responsive synthetic gene circuit developed herein responds to input cues from two key homeostatic transcriptional networks, enabling dynamic and tunable output. This proof-of-concept approach has the potential to match drug delivery to disease activity for optimal outcomes that addresses the complex environment of inflammatory arthritis.

synthetic biology↗

bioRxiv2025

Programmable chronogenetic gene circuits for self-regulated circadian delivery of biologic drugs

Cells of the body rely on the circadian clock to orchestrate daily changes in physiology that impact both homeostatic and pathological conditions, such as the inflammatory autoimmune disease rheumatoid arthritis (RA). In RA, high levels of proinflammatory cytokines peak early in the morning hours, reflected by daily changes in joint stiffness. Chronotherapy (or circadian medicine) seeks to delivery drugs at optimal times to maximize their efficacy. However, chronotherapy remains a largely unexplored approach for disease modifying, antirheumatic treatment, particularly for cell-based therapies. In this study, we developed autonomous chronogenetic gene circuits that produce the biologic drug interleukin-1 receptor antagonist (IL-1Ra) with desired phase and amplitude. We compared expression of IL-1Ra from circuits that contained different circadian promoter elements (E-boxes, D-boxes, or RREs) and their ability to respond to inflammatory challenges in murine pre-differentiated induced pluripotent stem cells (PDiPSC) or engineered cartilage pellets. We confirmed that each circuit reliably peaked at a distinct circadian time over multiple days. Engineered cells generated significant amounts of IL-1Ra on a circadian basis, which protected them from circadian dysregulation and inflammatory damage. These programmable chronogenetic circuits have the potential to align with an individuals circadian rhythm for optimized, self-regulated daily drug delivery.

synthetic biology↗

bioRxiv2025

Cryo-correlative light and electron tomography of dopaminergic axonal varicosities reveals non-synaptic modulation of cortico-striatal synapses

Dopamine is an essential brain neuromodulator involved in reward and motor control. Dopaminergic (DA) neurons project to most brain areas, with particularly dense innervation in the striatum. DA varicosities bind to target striatal synapses and form dopamine hub synapses (DHS). However, the basic features of dopamine release sites are still largely unknown. Here we studied the ultrastructure of fluorescent DA and glutamatergic (GLU) synaptosomes isolated from the striatum of adult mice with cryo-correlative light and electron microscopy and cryo-electron tomography. We observed that DA synaptosomes display [~]10 times fewer vesicles than GLU ones. DA vesicles are bigger and less round. Vesicle organization at single nanometer scale indicates that most GLU synaptosomes have tethered and primed vesicles, indicative of a readily releasable pool, while only 39 % of DA synaptosomes have tethered vesicles, which appear not to be primed. In addition, GLU terminals contacted by DA terminals in DHS have more primed vesicles than others. While DA varicosities do not form genuine synapses, their adhesion to cortico-striatal synapses may convey a local regulation of synaptic release properties.

neuroscience↗

bioRxiv2024

A minor impact of VGLUT1 expression level on quantal size revealed through the characterization of VGLUT1mEos2 knock-down new mouse model

Synaptic vesicles (SVs) are small organelles secreting neurotransmitters at synapses. By fusing a photoactivated fluorescent protein to VGLUT1, we generated a VGLUT1mEos2 knock-in mouse. VGLUT1mEos2 knock-in mice are viable and healthy, but exhibit a severe reduction in VGLUT1 expression levels. Using VGLUT1mEos2 expressing neurons, we established paradigms to trace individual SV mobility at the single-molecule level or via massive photoconversion. Hippocampal neurons with significantly diminished VGLUT1 expression maintain unaltered miniature glutamate release characteristics in terms of quantal size and frequency. We demonstrate that VGLUT1 expression level are not correlated in a linear fashion with the vesicular glutamate content. In conclusion, the VGLUT1mEos2 mouse line serves as a powerful tool for exploring SV mobility properties and elucidating the contributions of VGLUT1 to excitatory neurotransmission and cognitive processes.

neuroscience↗

bioRxiv2024

Damage sensing through TLR9 Promotes Viral Clearance and Recovery During Influenza Infection

Host response aimed at eliminating the infecting pathogen, as well as the pathogen itself, can cause tissue injury. Tissue injury leads to the release of a myriad of cellular components including mitochondrial DNA, which the host senses through pattern recognition receptors. How the sensing of tissue injury by the host shapes the anti-pathogen response remains poorly understood. In this study, we utilized mice that are deficient in toll-like receptor-9 (TLR9), which binds to unmethylated CpG DNA sequences such as those present in bacterial and mitochondrial DNA. To avoid direct pathogen sensing by TLR9, we utilized the influenza virus, which lacks ligands for TLR9, to determine how damage sensing by TLR9 contributes to anti-influenza immunity. Our data show that TLR9-mediated sensing of tissue damage promotes an inflammatory response during early infection, driven by the epithelial and myeloid cells. Along with the diminished inflammatory response, the absence of TLR9 led to impaired viral clearance manifested as a higher and prolonged influenza components in myeloid cells including monocytes and macrophages rendering them highly inflammatory. The persistent inflammation driven by infected myeloid cells led to persistent lung injury and impaired recovery in influenza-infected TLR9-/-mice. Further, we show elevated TLR9 activation in the plasma samples of patients with influenza and its association with the disease severity in hospitalized patients, demonstrating its clinical relevance. Overall, we demonstrate an essential role of damage sensing through TLR9 in promoting anti-influenza immunity and inflammatory response. Author SummaryTissue damage is an inevitable outcome of clinically relevant lung infections, but the host mechanisms for detecting such damage during infection are not well understood. We investigated the role of Toll-like receptor 9 (TLR9) in sensing tissue damage caused by influenza. Since influenza lacks TLR9 ligands, we hypothesized that TLR9 signaling is driven by tissue damage molecules like mitochondrial DNA (mtDNA). Our data indicate that TLR9 reduces early inflammatory lung injury but impairs viral clearance, resulting in extensive immune cell infection, persistent inflammation, and delayed recovery. Myeloid-specific TLR9 deletion ameliorated late-stage inflammatory responses. In humans, influenza-infected individuals exhibited elevated TLR9 activity and mtDNA levels in plasma compared to healthy controls, with higher TLR9 activation potential correlating with severe disease requiring ICU admission. These findings suggest that TLR9-mediated damage sensing triggers both inflammatory tissue injury and viral clearance. These data indicate that TLR9 activity can serve as a crucial biomarker and therapeutic target to limit influenza induced tissue injury.

immunology↗

bioRxiv2023

Aerosolized α1 adrenoreceptor antagonism does not affect experimentally induced lung fibrosis in animal models

Pulmonary Fibrosis is a progressive and incurable condition that complicates many disease states. Adrenergic hyperinnervation and accumulation of fibroblasts expressing 1- adrenoreceptors have been implicated in this process. Previous studies have demonstrated that systemic treatment with an 1-adrenoreceptors antagonist attenuates fibrotic endpoints in lung fibrosis models. In an attempt to develop a lung targeted therapy, we determined whether 1- adrenoreceptors antagonism delivered via inhaled administration of terazosin exerts antifibrotic benefits in experimentally induced lung fibrosis. C57/BL6 mice treated with bleomycin, or a doxycycline inducible line of transgenic mice with lung specific overexpression of the bioactive form of the human TGF{beta}1 (TGF{beta}1-Tg+ model), received nebulized terazosin at varying doses on a therapeutic schedule following the induction of fibrosis and were sacrificed at 21 days. Airway inflammation, fibrotic endpoints, and lung function were evaluated. 1-adrenoreceptors antagonism delivered via this method did not impact airway inflammation as indicated by bronchoalveolar lavage cell counts, and there was no significant difference observed in soluble collagen content. There was similarly no significant difference in respiratory mechanics with terazosin administration. These data show that inhaled delivery of the 1-adrenoreceptors antagonist terazosin by this method is ineffective at treating fibrosis in these models and suggest that alternative dosing schedules or delivery methods may be more fruitful avenues of investigation. Further exploration of these findings may provide new therapeutic options and illuminate mechanisms through which adrenergic innervation and 1-adrenoreceptors mediate fibrosis in the adult mammalian lung.

pathology↗

bioRxiv2023

Peripheral Blood Single-Cell Sequencing Uncovers Common and Specific Immune Aberrations in Fibrotic Lung Diseases

Rationale and ObjectivesThe extent and commonality of peripheral blood immune aberrations in fibrotic interstitial lung diseases are not well characterized. In this study, we aimed to identify common and distinct immune aberrations in patients with idiopathic pulmonary fibrosis (IPF) and fibrotic hypersensitivity pneumonitis (FHP) using cutting-edge single-cell profiling technologies. MethodsSingle-cell RNA sequencing was performed on patients and healthy controls peripheral blood and bronchoalveolar lavage samples using 10X Genomics 5 gene expression and V(D)J profiling. Cell type composition, transcriptional profiles, cellular trajectories and signaling, and T and B cell receptor repertoires were studied. The standard Seurat R pipeline was followed for cell type composition and differential gene expression analyses. Transcription factor activity was imputed using the DoRothEA-VIPER algorithm. Pseudotime analyses were conducted using Monocle3, while RNA velocity analyses were performed with Velocyto, scVelo, and CellRank. Cell-cell connectomics were assessed using the Connectome R package. V(D)J analyses were conducted using CellRanger and Immcantation frameworks. Across all analyses, disease group differences were assessed using the Wilcoxon rank-sum test. Measurements and Main Results327,990 cells from 83 samples were profiled. Overall, changes in monocytes were common to IPF and FHP, whereas lymphocytes exhibited disease-specific aberrations. Both diseases displayed enrichment of CCL3hi/CCL4hi CD14+ monocytes (p<2.2e-16) and S100Ahi CD14+ monocytes (p<2.2e-16) versus controls. Trajectory and RNA velocity analysis suggested that pro-fibrotic macrophages observed in BAL originated from peripheral blood monocytes. Lymphocytes exhibited disease-specific aberrations, with CD8+ GZMKhi T cells and activated B cells primarily enriched in FHP patients. V(D)J analyses revealed unique T and B cell receptor complementarity-determining region 3 (CDR3) amino acid compositions (p<0.05) in FHP and significant IgA enrichment in IPF (p<5.2e-7). ConclusionsWe identified common and disease-specific immune mechanisms in IPF and FHP; S100Ahi monocytes and SPP1hi macrophages are common to IPF and FHP, whereas GMZKhi T lymphocytes and T and B cell receptor repertoires were unique in FHP. Our findings open novel strategies for the diagnosis and treatment of IPF and FHP.

genomics↗

bioRxiv2023

Kv12-Encoded K+ Channels Drive the Day-Night Switch in the Repetitive Firing Rates of SCN Neurons

Considerable evidence suggests that day-night rhythms in the functional expression of subthreshold potassium (K+) channels regulate daily oscillations in the rates of spontaneous action potential firing of neurons in the suprachiasmatic nucleus (SCN), the master circadian pacemaker in mammals. The K+ conductance(s) driving these daily rhythms in repetitive firing rates, however, have not been identified. To test the hypothesis that subthreshold Kv12.1/Kv12.2-encoded K+ channels play a role, we obtained current-clamp recordings from SCN neurons in slices prepared from adult mice harboring targeted disruptions in the Kcnh8 (Kv12.1-/-) or Kcnh3 (Kv12.2-/-) locus. We found that mean nighttime repetitive firing rates were higher in Kv12.1-/- and Kv12.2-/-, than in wild type (WT), SCN neurons. In marked contrast, mean daytime repetitive firing rates were similar in Kv12.1-/-, Kv12.2-/- and WT SCN neurons, and the day-night difference in mean repetitive firing rates, a hallmark feature of WT SCN neurons, was eliminated in Kv12.1-/- and Kv12.2-/- SCN neurons. Similar results were obtained with in vivo shRNA-mediated acute knockdown of Kv12.1 or Kv12.2 in adult SCN neurons. Voltage-clamp experiments revealed that Kv12-encoded current densities in WT SCN neurons are higher at night than during the day. In addition, pharmacological block of Kv12-encoded currents increased the mean repetitive firing rate of nighttime, but not daytime, in WT SCN neurons. Dynamic clamp-mediated subtraction of modeled Kv12-encoded currents also selectively increased the mean repetitive firing rates of nighttime WT SCN neurons. Despite the elimination of nighttime decrease in the mean repetitive firing rates of SCN neurons, however, locomotor (wheel-running) activity remained rhythmic in Kv12.1-/-, Kv12.2-/-, Kv12.1-targeted shRNA-expressing, and Kv12.2-targeted shRNA-expressing animals.

neuroscience↗

bioRxiv2021

Subcellular and regional localization of mRNA translation in midbrain dopamine neurons

Local translation within excitatory and inhibitory neurons is involved in neuronal development and synaptic plasticity. Despite the extensive dendritic and axonal arborizations of central monoaminergic neurons, the subcellular localization of protein synthesis is not well-characterized in these populations. Here, we investigated mRNA localization and translation in midbrain dopaminergic (mDA) neurons, cells with enormous axonal and dendritic projections, both of which exhibit stimulation-evoked dopamine (DA) release. Using highly-sensitive ribosome-bound RNA-sequencing and imaging approaches in mDA axons, we found no evidence for axonal mRNA localization or translation. In contrast, mDA neuronal dendritic projections into the substantia nigra reticulata (SNr) contain ribosomes and mRNAs encoding the major components of DA synthesis, release, and reuptake machinery. Surprisingly, we also observed dendritic localization of mRNAs encoding synaptic vesicle-related proteins, including those involved in vesicular exocytic fusion. Our results are consistent with a role for local translation in the regulation of DA release from dendrites, but not from axons. Our translatome data further defined a molecular signature of the sparse mDA neurons resident in the SNr, including enrichment of Atp2a3/SERCA3, an ER calcium pump previously undescribed in mDA neurons.

neuroscience↗

bioRxiv2020

Cobalt(III) Schiff Base complexes stabilize non-fibrillar amyloid-β aggregates with reduced toxicity

The aggregation of A{beta} is believed to be foundational to the pathogenesis of Alzheimers disease (AD). In vitro aggregation kinetics have been shown to correlate with rates of disease progression in both AD patients and animal models, thus proving to be a useful metric for testing A{beta}-targeted therapeutics. Here we present evidence of Cobalt(III) Schiff base complex (Co(III)-sb) modulation of A{beta} aggregation kinetics by a variety of complementary techniques. These include Thioflavin T (ThT) fluorescence, circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). Our data was fitted to kinetic rate laws using a mathematical model developed by Knowles et al. in order to extract mechanistic information about the effect of Co(III)-sb on aggregation kinetics. Our analysis revealed that Co(III)-sb significantly decreases the kinetic parameter k+, and significantly increases the polymerization rate kn, suggesting that Co(III)-sb causes A{beta} to rapidly form stable oligomeric species that are unable to elongate into mature fibrils. This result was corroborated by TEM and AFM of A{beta} aggregates in vitro. We also demonstrate that A{beta} aggregate mixtures produced in the presence of Co(III)-sb exhibit decreased cytotoxicity compared to untreated samples. Statement of SignificanceAmyloid-{beta} is thought to be a key mediator in the pathology of Alzheimers disease, yet its precise mechanisms of toxicity are poorly understood. The interaction of A{beta} with endogenous metal ions via its N terminal Histidine residues has been shown to alter the peptides aggregation and toxicity. As such, metal-based complexes have been developed both as therapeutic agents as well as tools for investigating the role of metal binding in the pathogenesis of AD. This work expands on our previous studies developing Cobalt(III) Schiff base complexes as amyloid inhibitors. Here we demonstrate effective inhibition of aggregation by various complementary modalities. Additionally we show that Co(III)-sb reduces the toxicity of A{beta} aggregates to cells in culture.

neuroscience↗

bioRxiv2020

Synaptic and supra-synaptic organisation of the dopaminergic projection to the striatum.

Dopamine is a monoamine involved in reward processing and motor control. Volume transmission is thought to be the mechanism by which monoamines modulate effector systems at glutamate and GABA synapses. Hence, dopamine synapses are scarcely described. We applied fluorescence activated synaptosome sorting to explore the features of the dopaminergic synaptome. We provide the proteome of striatal dopaminergic synapses with 57 proteins specifically enriched. Beyond canonical markers of dopamine neurotransmission (Th, Slc6a3/DAT, Slc18a2/VMAT2), we validated 6 proteins belonging to pre- and postsynaptic sides (Cpne7, Apba1/Mint1, Cadps2, Cadm2/SynCAM 2, Stx4 and Mgll). Moreover, dopaminergic varicosities adhere to both a post-synapse with cognate receptors and glutamatergic, GABAergic or cholinergic synapses in structures we named dopaminergic "hub synapses". Markers of presynaptic vesicles and active zone, post-synaptic density and spine apparatus, are significantly increased upon association with dopamine inputs in hubs. Thus neuromodulation frequently operates from hub synapses affecting associated synapses and is not solely dependent on volume transmission. Finally, FASS provides a new framework for the exploration of dopaminergic synapses and more generally for discrete synapse populations ex-vivo. HighlightsO_LIA first proteome of dopaminergic synapses in the striatum C_LIO_LIStriatal dopaminergic synaptosomes display post-synaptic cognate receptors C_LIO_LIDopaminergic projections build hub synapses with excitatory, inhibitory, and cholinergic projections. C_LIO_LICortico-striatal synaptic scaffolds are strengthened upon association in hub synapses. C_LI

neuroscience↗

bioRxiv2018

Mammalian vesicular glutamate transporter VGLUT1 reduces synaptic vesicle superpool size and spontaneous release frequency.

Glutamate secretion at excitatory synapses is tightly regulated to allow for the precise tuning of synaptic strength. Vesicular Glutamate Transporters (VGLUT) accumulate glutamate into synaptic vesicles (SV) and thereby regulate quantal size. Further, the number of release sites and the release probability of SVs maybe regulated by the organization of active zone proteins and SV clusters. In the present work, we uncover a mechanism mediating an increased SV clustering through a tripartite interaction of VGLUT1, endophilinA1 and intersectin1. This strengthening of SV clusters results in a combined reduction of axonal SV super-pool size and miniature excitatory events frequency. Our findings support a model in which clustered vesicles are held together through multiple weak interactions between SH3 domains and proline rich sequences of synaptic proteins. In mammals, VGLUT1 gained a poly-proline sequence that recruits endophilinA1 and turns the transporter into a dual regulator of quantal release parameters at excitatory synapses.

neuroscience↗