Biology subjects

Dore, K.

Publications and source records attributed to Dore, K..

6 recordsLinked to original sources

bioRxiv2026

Excessive cholesterol accumulation in microglia increases neuronal synaptic vulnerability to amyloid-beta

Cholesterol efflux is an important determinant of cellular lipid homeostasis. However, how microglial excessive cholesterol accumulation affects neuronal synaptic integrity remains poorly understood, particularly in the context of Alzheimer's disease. Here, we utilized a conditional knockout mouse model targeting the cholesterol transporters ABCA1 and ABCG1 in microglia. The microglia-specific ABCA1/ABCG1 deficiency triggered marked cholesterol accumulation, microglial hypertrophy, downregulation of the homeostatic marker P2ry12, and upregulation of the reactivity-associated marker CD11b, indicating shift toward a reactive phenotype. This phenotype was accompanied by increased reactive oxygen species, consistent with enhanced oxidative stress in ABCA1/ABCG1-deficient microglia compared with control. Using organotypic hippocampal slice cultures, we investigated the downstream neuronal outcomes of microglial ABCA1/ABCG1 deficiency. Under basal conditions, microglial ABCA1/ABCG1 knockdown did not significantly alter dendritic spine density in CA1 pyramidal neurons. However, upon exposure to amyloid-beta (A{beta}) stress, microglial ABCA1/ABCG1 deficiency markedly exacerbated dendritic spine loss in CA1 pyramidal neurons. Taken together, our findings highlight an important role for ABCA1/ABCG1-dependent cholesterol efflux in maintaining microglial homeostasis and limiting neuronal synaptic vulnerability to A{beta}-associated stress. These results support further investigation of microglial cholesterol transport as a potential target for preserving synaptic resilience in Alzheimer's disease.

neuroscience↗

bioRxiv2026

ESCRT-0 regulates AMPA receptor currents and Ca2+- dependent signaling

Membrane protein trafficking is essential for synaptic growth, maintenance, function, and plasticity, and involves the regulated exocytosis and endocytosis of proteins to and from the pre-and post-synaptic membranes. Defects in the clearance of membrane proteins can lead to the accumulation of ubiquitinated membrane proteins and contribute to neurodegenerative disease. The ESCRT (endosomal sorting complexes required for transport) machinery binds and sorts ubiquitinated membrane proteins into lysosomes for degradation, yet the presence and function of ESCRTs in sorting ubiquitinated AMPA and other receptors at the post-synapse remain unclear. Here we show that the ubiquitin-binding ESCRT-0 protein, Hrs, localizes to both pre- and post-synapses, and levels are modulated by neuronal activity, increasing and decreasing with higher and lower neuronal activity, respectively. Phosphoproteomic profiling of Hrs-depleted post-synaptic membranes revealed a role for Hrs in glutamatergic synaptic transmission, including long-term potentiation. In addition, Hrs-depleted neurons showed faster AMPAR current kinetics and reduced amplitude in whole-cell patch-clamp recordings. Genetic deletion of neuronal Hgs in mice led to reductions in phosphorylated CaMKII- and -{beta} (T286/T287) and structural proteins, PSD-95 and gephyrin, suggestive of LTD (long-term depression)-like synaptic depression. In contrast, Hrs overexpression led to increases in Ca2+-dependent signaling, including protein kinase C (PKC) and PKC substrate, AMPAR subunit GluA1-S831, a site which increases conductance. Together, these findings identify a dynamic, bidirectional role for Hrs at the post-synapse as it both senses and is modulated by neuronal activity, ultimately impacting excitatory synaptic strength. Significance StatementSynaptic plasticity relies on dynamic trafficking and turnover of membrane proteins, including AMPA-type glutamate receptors (AMPARs), yet how receptor trafficking intersects with ubiquitin-mediated sorting pathways at synapses remains unclear. We show that the ubiquitin-binding ESCRT-0 protein, Hrs, localizes to both pre- and post-synapses, and its abundance is bidirectionally regulated by neuronal activity. Genetic depletion of Hrs in mice reduces CaMKII phosphorylation and impacts AMPAR channel surface localization. In contrast, neuronal-specific Hrs overexpression led to enhanced GluA1 and protein kinase C substrate phosphorylation, suggesting altered AMPAR trafficking, subunit composition, and/or function. Thus, Hrs emerges as a modulator of glutamatergic signaling, coupling ubiquitin-mediated receptor sorting to the fine-tuning of synaptic transmission, with direct implications for learning and memory in health and disease.

neuroscience↗

bioRxiv2025

Human dorsal root ganglia neuronal cell line to study nociceptive signaling: a new pipeline for pain therapy.

Nociceptive afferent neurons within the dorsal root ganglion (DRG) detect and relay painful stimuli from the periphery to the brain, and the malfunctioning of this process leads to sustained pain states. Animal model studies have been invaluable for demonstrating the importance of the DRG nociceptor in pain sensation and the development of related analgesic targets. However, there are functional biological differences between human and animal model nociceptors. Therefore, a complementary in vitro model of human nociception is critical to confirming the relevance of preclinical findings for therapeutic drug development. We characterized the nociceptive properties of differentiated cells from the human DRG-derived immortalized cell line HD10.6. Within differentiated HD10.6 cells, we documented the abundance and localization of nociceptive machinery central to regulating excitability and linked with pain sensation including ion channels TRPV1 and NaV1.7 and afferent peptides CGRP and Substance P. Using calcium influx imaging assays, we confirmed the electrical functionality of TRPV1 and NaV1.7 in HD10.6 cells, and through whole-cell patch clamp, we found similar baseline electrophysiological parameters of HD10.6 cells to those previously observed in human patient DRGs. Further, we found that differentiated HD10.6 cells express the mu opioid receptor 1 protein, and DAMGO, a mu agonist, blocks depolarization-evoked calcium influx in a naloxone-reversible fashion. Importantly, using an inflammatory cocktail, excitation and peripheral sensitization are induced within HD10.6 cells, mirroring nociceptors in a pain state during or after tissue damage or inflammation. Finally, HD10.6 cells were also cultured into dual-chambered microfluidic devices to mirror the biological anatomy of the nociceptor. Within this system, we demonstrated the uptake of adeno-associated-virus (AAV) by the peripheral terminals and AAV transport to the soma. Altogether, we have developed the use of HD10.6 cells to create a system of human nociceptive signaling on a chip to study human nociceptor physiology and intervention. PerspectiveThere are essential differences between human and animal model nociceptors. Here, we develop a physiological model of "nociceptive signaling on a chip" using human-derived nociceptors to ultimately enhance the translatability of preclinical afferent signaling research to the human patient.

neuroscience↗

bioRxiv2025

Analgesic actions of Intrathecal NaV 1.7 antisense in rats: loss of antagonist channel binding, message depletion, and neuraxial distribution of oligonucleotide

BackgroundGenome targeting strategies to address NaV 1.7 mediated signaling in nociceptive afferents produce highly selective and persistent analgesic outcomes. Here, we analyze the concentration-dependent effects of the reduction of primary afferent NaV 1.7 channel expression by intrathecal delivery of an antisense oligonucleotide on pain behaviors and the covariance of Scn9a knock-down on NaV 1.7 message expression and channel binding. MethodsMale Sprague-Dawley rats were implanted with lumbar intrathecal catheters and dosed with different NaV 1.7 ASO concentrations (100 to 3000 g;10 L). Pain behavior assays were conducted 0-28 days after ASO injections. Brain, spinal cords (SC) and dorsal root ganglia (DRGs) were collected. Quantification of ASO knock-down was assessed through RT-qPCR. NaV 1.7 expression was assessed by binding of NaV 1.7 fluorescent labeled antagonist (ATTO488PTx-II). Distribution studies were performed using anti-ASO antibody staining in brain, SCs and DRGs. ResultsNaV 1.7 message was detected in nerve, DRG and SC. Intrathecal ASO induced a concentration dependent gradient of knock down in DRGs (lumbar to cervical) of Scn9a mRNA and ATTO488PTx-II binding in small DRG neurons, and in spinal parenchyma, and a suppression of pain behaviors initiated by mechanical compression, inflammation and following intraplantar NaV1.7 agonist (OD1) or formalin. At 1000 {micro}g, there was a 47% reduction in phase 2 flinching, a 60% reduction in DRG mRNA and a 36% reduction in ATTO488PTx-II DRG binding in comparison with mismatch controls. Although marked changes were seen at the sensory ganglia level and spinal dorsal horn, no changes in NaV 1.7 binding or mRNA were detected in sciatic nerves. Reduction in DRG message displayed a rostrocaudal gradient that corresponded with ASO distribution. ConclusionsThe study presents how NaV 1.7 ASOs reduce primary afferent channel binding through an effective knock-down on Scn9a mRNA, and channel binding leading to a covariate reduction in pain behavior.

neuroscience↗

bioRxiv2024

D-Serine inhibits non-ionotropic NMDA receptor signaling

NMDA-type glutamate receptors (NMDARs) are widely recognized as master regulators of synaptic plasticity, most notably for driving long-term changes in synapse size and strength that support learning. NMDARs are unique among neurotransmitter receptors in that they require binding of both neurotransmitter (glutamate) and co-agonist (e.g. O_SCPLOWDC_SCPLOW-serine) to open the receptor channel, which leads to the influx of calcium ions that drive synaptic plasticity. Over the past decade, evidence has accumulated that NMDARs also support synaptic plasticity via ion flux-independent (non-ionotropic) signaling upon the binding of glutamate in the absence of co-agonist, although conflicting results have led to significant controversy. Here, we hypothesized that a major source of contradictory results can be attributed to variable occupancy of the co-agonist binding site under different experimental conditions. To test this hypothesis, we manipulated co-agonist availability in acute hippocampal slices from mice of both sexes. We found that enzymatic scavenging of endogenous co-agonists enhanced the magnitude of LTD induced by non-ionotropic NMDAR signaling in the presence of the NMDAR pore blocker, MK801. Conversely, a saturating concentration of O_SCPLOWDC_SCPLOW-serine completely inhibited both LTD and spine shrinkage induced by glutamate binding in the presence of MK801. Using a FRET-based assay in cultured neurons, we further found that O_SCPLOWDC_SCPLOW-serine completely blocked NMDA-induced conformational movements of the GluN1 cytoplasmic domains in the presence of MK801. Our results support a model in which O_SCPLOWDC_SCPLOW-serine inhibits ion flux-independent NMDAR signaling and plasticity, and thus O_SCPLOWDC_SCPLOW-serine availability could serve to modulate NMDAR signaling even when the NMDAR is blocked by magnesium. Significance StatementNMDARs are glutamate-gated cation channels that are key regulators of neurodevelopment and synaptic plasticity and unique in their requirement for binding of a co-agonist (e.g. O_SCPLOWDC_SCPLOW-serine) in order for the channel to open. NMDARs have been found to drive synaptic plasticity via non-ionotropic (ion flux-independent) signaling upon the binding of glutamate in the absence of co-agonist, though conflicting results have led to controversy. Here, we found that O_SCPLOWDC_SCPLOW-serine inhibits non-ionotropic NMDAR-mediated LTD and LTD-associated spine shrinkage. Thus, a major source of the contradictory findings might be attributed to experimental variability in O_SCPLOWDC_SCPLOW-serine availability. In addition, the developmental regulation of O_SCPLOWDC_SCPLOW-serine levels suggests a role for non-ionotropic NMDAR plasticity during critical periods of plasticity.

neuroscience↗

bioRxiv2018

SYNPLA: A synapse-specific method for identifying learning-induced synaptic plasticity loci

Which neural circuits undergo synaptic changes when an animal learns? Although it is widely accepted that changes in synaptic strength underlie many forms of learning and memory, it remains challenging to connect changes in synaptic strength at specific neural pathways to specific behaviors and memories. Here we introduce SYNPLA (SYNaptic Proximity Ligation Assay), a synapse-specific, high-throughput and potentially brain-wide method capable of detecting circuit-specific learning-induced synaptic plasticity.

neuroscience↗