Biology subjects

Bender, K.

Publications and source records attributed to Bender, K..

10 recordsLinked to original sources

bioRxiv2025

D3 dopamine receptors implicate a subtype of medium spiny neuron in the aversive effects of antipsychotic medications

Second generation antipsychotics (SGAs) are widely used clinical tools; yet, they often cause negative side effects and take weeks to become effective, leading to poor patient compliance. The effect/side effect profile of individual SGAs is highly variable, and the mechanisms that underlie this variability are not well understood. Here, we identify a role of type 3 dopamine receptor (D3R) neurons in the Nucleus Accumbens (NAc) that mimics the aversive effects of quetiapine. Using single-nucleus RNA sequencing, we show that D3R is expressed in a subpopulation of D1R neurons and defines a distinct NAc cell type. We found that both clozapine and quetiapine cause acute conditioned place aversion in mice, but aversion subsides only after 21 days of treatment with quetiapine, a drug characterized as an arrestin-biased agonist at D3R. We provide evidence at both the cellular and population level that quetiapine inhibits D3R-expressing neurons in the lateral shell (LatSh) of the NAc. We also demonstrate that local injection of quetiapine into LatSh NAc is sufficient to cause place aversion. Selective optogenetic inhibition of D3R-neurons in the LatSh produces real time place aversion in mice, correlating this cell type to the aversive effects of quetiapine. These findings suggest a cell-type-specific mechanism underlying quetiapine-induced aversion and its potential attenuation with chronic treatment, offering insight into the cell types and circuitry that shape the quetiapine side effect profile.

neuroscience↗

bioRxiv2025

Heterocellular and homocellular electrically coupled networks of the thalamus and cortex revealed by focal photomapping

Electrical synapses are expressed ubiquitously across the brain and are crucial components of active neural circuitry and connectomes. Identification of coupled networks in living tissue is limited by technical demands of multiplexed recordings, and no dyes, fluorescent reporters, or genetic labels can currently fill the gap. We introduce a novel method of identifying and quantifying electrical synapses, opto-{delta}L, that combines focal photostimulation of soma-targeted opsins with a spike timing-based computation for the strength of electrical synapses to rapidly measure and map electrically coupled networks in vitro. We leverage opto-{delta}L to show that coupled networks of the mature thalamic reticular nucleus extend as far as 100 m, synapse promiscuously across genetic subtypes of neurons, and couple 1-4 neighboring neurons to each recorded hub cell. We also demonstrate application of opto-{delta}L to cortical networks. These results highlight the broad potential of opto-{delta}L to interrogate the identity and roles of electrical synapses in circuitry, behavior, and cognition. TeaserElectrically coupled neural networks are newly unmasked by functional photomapping.

neuroscience↗

bioRxiv2024

Delta opioid receptors engage multiple signaling cascades to differentially modulate prefrontal GABA release with input and target specificity

Opioids regulate circuits associated with motivation and reward across the brain. Of the opioid receptor types, delta opioid receptors (DORs) appear to have a unique role in regulating the activity of circuits related to reward without a liability for abuse. In neocortex, DORs are expressed primarily in interneurons, including parvalbumin- and somatostatin-expressing interneurons that inhibit somatic and dendritic compartments of excitatory pyramidal cells, respectively. But how DORs regulate transmission from these key interneuron classes is unclear. We found that DORs regulate inhibition from these interneuron classes using different G-protein signaling pathways that both converge on presynaptic calcium channels, but regulate distinct aspects of calcium channel function. This imposes different temporal filtering effects, via short-term plasticity, that depend on how calcium channels are regulated. Thus, DORs engage differential signaling cascades to regulate inhibition depending on the postsynaptic target compartment, with different effects on synaptic information transfer in somatic and dendritic domains.

neuroscience↗

bioRxiv2023

Impaired cerebellar plasticity hypersensitizessensory reflexes in SCN2A-associated ASD

Children diagnosed with autism spectrum disorder (ASD) commonly present with sensory hypersensitivity, or abnormally strong reactions to sensory stimuli. Such hypersensitivity can be overwhelming, causing high levels of distress that contribute markedly to the negative aspects of the disorder. Here, we identify the mechanisms that underlie hypersensitivity in a sensorimotor reflex found to be altered in humans and in mice with loss-of-function in the ASD risk-factor gene SCN2A. The cerebellum-dependent vestibulo-ocular reflex (VOR), which helps maintain ones gaze during movement, was hypersensitized due to deficits in cerebellar synaptic plasticity. Heterozygous loss of SCN2A-encoded NaV1.2 sodium channels in granule cells impaired high-frequency transmission to Purkinje cells and long-term potentiation, a form of synaptic plasticity important for modulating VOR gain. VOR plasticity could be rescued in adolescent mice via a CRISPR-activator approach that increases Scn2a expression, highlighting how evaluation of simple reflexes can be used as quantitative readout of therapeutic interventions.

neuroscience↗

bioRxiv2022

Arrestin-3 agonism at D3 dopamine receptors defines a subclass of second generation antipsychotics that promotes drug tolerance

Second generation antipsychotics (SGAs) are front-line treatments for serious mental illness. Often, individual patients benefit only from some SGAs and not others. The mechanisms underlying this unpredictability in treatment efficacy remain unclear. All SGAs bind the D3 dopamine receptor (D3R) and are traditionally considered antagonists for dopamine receptor signaling. Here, we report that some clinically important SGAs function as arrestin-3 agonists at D3R, resulting in modulation of calcium channels localized to the site of action potential initiation in prefrontal cortex pyramidal neurons. We further show that chronic treatment with an arrestin-3 agonist-SGA, but not an antagonist-SGA, abolishes D3R function through post-endocytic receptor degradation by G-protein coupled receptor-associated sorting protein-1 (GASP1). These results implicate D3R-arrestin-3 signaling as a source of SGA variability, highlighting the importance of including arrestin-3 signaling in characterizations of drug action. Furthermore, they suggest that post-endocytic receptor trafficking that occurs during chronic SGA treatment may contribute to treatment efficacy.

neuroscience↗

bioRxiv2022

Physical and functional convergence of the autism risk genes Scn2a and Ank2 in neocortical pyramidal cell dendrites

Dysfunction in sodium channels and their ankyrin scaffolding partners have both been implicated in neurodevelopmental disorders, including autism spectrum disorder (ASD). In particular, the genes SCN2A, which encodes the sodium channel NaV1.2, and ANK2, which encodes ankyrin-B, have strong ASD association. Recent studies indicate that ASD-associated haploinsufficiency in Scn2a impairs dendritic excitability and synaptic function in neocortical pyramidal cells, but how NaV1.2 is anchored within dendritic regions is unknown. Here, we show that ankyrin-B is essential for scaffolding NaV1.2 to the dendritic membrane of mouse neocortical neurons, and that haploinsufficiency of Ank2 phenocopies intrinsic dendritic excitability and synaptic deficits observed in Scn2a+/- conditions. Thus, these results establish a direct, convergent link between two major ASD risk genes and reinforce an emerging framework suggesting that neocortical pyramidal cell dendritic dysfunction can be etiological to neurodevelopmental disorder pathophysiology.

neuroscience↗

bioRxiv2020

Developmental dynamics of voltage-gated sodium channel isoform expression in the human and mouse neocortex

ObjectiveGenetic variants in the voltage-gated sodium channels SCN1A, SCN2A, SCN3A, and SCN8A are leading causes of epilepsy, developmental delay, and autism spectrum disorder. The mRNA splicing patterns of all four genes vary across development in the rodent brain, including mutually exclusive copies of the fifth protein-coding exon detected in the neonate (5N) and adult (5A). A second pair of mutually exclusive exons is reported in SCN8A only (18N and 18A). We aimed to quantify the expression of individual exons in the developing human neocortex. MethodsRNA-seq data from 176 human dorsolateral prefrontal cortex samples across development were analyzed to estimate exon-level expression. Developmental changes in exon utilization were validated by assessing intron splicing. Exon expression was also estimated in RNA-seq data from 58 developing mouse neocortical samples. ResultsIn the mature human neocortex, exon 5A is consistently expressed at least 4-fold higher than exon 5N in all four genes. For SCN2A, SCN3A, and SCN8A a synchronized 5N/5A transition occurs between 24 post-conceptual weeks (2nd trimester) and six years of age. In mice, the equivalent 5N/5A transition begins at or before embryonic day 15.5. In SCN8A, over 90% of transcripts in the mature human cortex include exon 18A. Early in fetal development, most transcripts include 18N or skip both 18N and 18A, with a transition to 18A inclusion occurring from 13 post-conceptual weeks to 6 months of age. No other protein-coding exons showed comparably dynamic developmental trajectories. SignificanceSplice isoforms, which alter the biophysical properties of the encoded channels, may account for some of the observed phenotypic differences across development and between specific variants. Manipulation of the proportion of splicing isoforms at appropriate stages of development may act as a therapeutic strategy for specific mutations or even epilepsy in general.

genetics↗

bioRxiv2018

Checkpoint adaptation in repair-deficient cells drives aneuploidy and resistance to genotoxic agents

Human cancers frequently harbour mutations in DNA repair genes, rendering the use of DNA damaging agents as an effective therapeutic intervention. As therapy-resistant cells often arise, it is important to better understand the molecular pathways that drive resistance in order to facilitate the eventual targeting of such processes. We employ repair-defective diploid yeast as a model to demonstrate that, in response to genotoxic challenges, nearly all cells eventually undergo checkpoint adaptation, resulting in the generation of aneuploid cells with whole chromosome losses that have acquired resistance to the initial genotoxic challenge. We demonstrate that adaptation inhibition, either pharmacologically, or genetically, drastically reduces the occurrence of resistant cells. Additionally, the aneuploid phenotypes of the resistant cells can be specifically targeted to induce cytotoxicity. We provide evidence that TORC1 inhibition with rapamycin, in combination with DNA damaging agents, can prevent both checkpoint adaptation and the continued growth of aneuploid resistant cells.

cell biology↗

bioRxiv2018

Knock-in rats expressing Cre and Flp recombinases at the Parvalbumin locus.

Rats have the ability to learn and perform sophisticated behavioral tasks, making them very useful for investigating neural circuit functions. In contrast to the extensive mouse genetic toolkit, the paucity of recombinase-expressing rat models has limited the ability to monitor and manipulate molecularly-defined neural populations in this species. Here we report the generation and validation of two knock-in rat strains expressing either Cre or Flp recombinase under the control of Parvalbumin (Pvalb), a gene expressed in the critical \"fast-spiking\" subset of inhibitory interneurons (FSIs). These strains were generated with CRISPR-Cas9 gene editing and show highly specific and penetrant labeling of Pvalb-expressing neurons, as demonstrated by in situ hybridization and immunohistochemistry. We validated these models in both prefrontal cortex and striatum using both ex vivo and in vivo approaches, including whole-cell recording, optogenetics, extracellular physiology and photometry. Our results demonstrate the utility of these new transgenic models for a wide range of neuroscience experiments.

neuroscience↗

bioRxiv2018

The autism-associated gene Scn2a plays an essential role in synaptic stability and learning

Autism spectrum disorder (ASD) is strongly associated with de novo gene mutations. One of the most commonly affected genes is SCN2A. ASD-associated SCN2A mutations impair the encoded protein NaV1.2, a sodium channel important for action potential initiation and propagation in developing excitatory cortical neurons. The link between an axonal sodium channel and ASD, a disorder typically attributed to synaptic or transcriptional dysfunction, is unclear. Here, we show NaV1.2 is unexpectedly critical for dendritic excitability and synaptic function in mature pyramidal neurons, in addition to regulating early developmental axonal excitability. NaV1.2 loss reduced action potential backpropagation into dendrites, impairing synaptic plasticity and synaptic stability, even when NaV1.2 expression was disrupted late in development. Furthermore, we identified behavioral impairments in learning and sociability, paralleling observations in children with SCN2A loss. These results reveal a novel dendritic function for NaV1.2, providing insight into cellular mechanisms likely underlying circuit and behavioral dysfunction in ASD.

neuroscience↗