Biology subjects

Lipscombe, D.

Publications and source records attributed to Lipscombe, D..

16 recordsLinked to original sources

bioRxiv2025

Control of Synaptic Communication through Molecularly Engineered Bioluminescence Light Emission and Sensing

Synapses are sites of intercellular communication between neurons and from neurons to target organs, and of signal integration that underly physiological and behavioral responses. We have developed a modular platform, Interluminescence (Int), for experimental control of synaptic transmission: bioluminescent light, generated by a luciferase oxidizing a luciferin, from a presynaptic neuron is used to activate transsynaptic optogenetic ion channels in the postsynaptic neuron. Two strategies can modulate postsynaptic neurons in the presence of luciferin. In the Act-Int approach, a luciferase is genetically expressed in synaptic vesicles and released during depolarization-induced presynaptic vesicle fusion and exocytosis. In the Persist-Int approach, a luciferase is tethered to the presynaptic membrane where it can support sustained transsynaptic signaling. Both strategies can activate postsynaptic neurons with comparable efficacy under the conditions tested. By design, the modularity of the platform permits the use of luciferases and opsins ranging in brightness and light sensitivity, with the luciferase targeted to different subcellular regions of the presynaptic neuron, and the postsynaptic opsin being excitatory or inhibitory. Our results demonstrate the utility and versatility of Interluminescence to mediate synapse-specific transmission that is either activity-dependent or activity-independent.

neuroscience↗

bioRxiv2025

Trpv1-dependent Cacna1b gene inactivation reveals cell-specific functions of CaV2.2 channels in vivo

Voltage-gated CaV2.2 channels underlie the N-type current, and they regulate calcium entry at many presynaptic nerve endings to control transmitter release. A role for CaV2.2 channels has been well-established in the transmission of pain information using pharmacological and global gene inactivated mouse models. However, investigation of the cell-specific actions of CaV2.2 channels would benefit from the availability of cell-restricted knockout mouse models and particularly in dissecting behavioral responses that depend on CaV2.2 channel activity. Here, we show the importance of CaV2.2 channels in Trpv1-lineage neurons in behavioral responses to sensory stimuli using Cre-dependent inactivation of the Cacna1b gene. Our work shows the cell- type specificity of CaV2.2 channels in mediating rapidly developing heat hypersensitivity and the utility of Cre-dependent inactivation of Cacna1b to discern cell-specific CaV2.2 channel functions.

neuroscience↗

bioRxiv2024

Peripheral CaV2.2 channels in skin regulate prolonged heat hypersensitivity during neuroinflammation

Neuroinflammation can lead to chronic maladaptive pain affecting millions of people worldwide. Neurotransmitters, cytokines, and ion channels are implicated in neuro-immune cell signaling but their roles in specific behavioral responses are not fully elucidated. Voltage-gated CaV2.2 channel activity in skin controls rapid and transient heat hypersensitivity induced by intradermal capsaicin via IL-1 cytokine signaling. CaV2.2 channels are not, however, involved in mechanical hypersensitivity that developed in the same animal model. Here, we show that CaV2.2 channels are also critical for heat hypersensitivity induced by the intradermal (id) Complete Freunds Adjuvant (CFA) model of chronic neuroinflammation that involves ongoing cytokine signaling for days. Ongoing CFA-induced cytokine signaling cascades in skin lead to pronounced edema, and hypersensitivity to sensory stimuli. Peripheral CaV2.2 channel activity in skin is required for the full development and week-long time course of heat hypersensitivity induced by id CFA. CaV2.2 channels, by contrast, are not involved in paw edema and mechanical hypersensitivity. CFA induced increases in cytokines in hind paws including IL-6 which was dependent on CaV2.2 channel activity. Using IL-6 specific neutralizing antibodies, we show that IL-6 contributes to heat hypersensitivity and, neutralizing both IL-1 and IL-6 was even more effective at reducing the magnitude and duration of CFA-induced heat hypersensitivity. Our findings demonstrate a functional link between CaV2.2 channel activity and the release of IL-6 in skin and show that CaV2.2 channels have a privileged role in the induction and maintenance of heat hypersensitivity during chronic forms of neuroinflammation in skin. Significance StatementNeuroinflammation can lead to chronic maladaptive pain. Neurotransmitters, ion channels, cytokines, and cytokine receptors are implicated in neuron-immune signaling, but their importance in mediating specific behavioral responses are not fully elucidated. We show that the activity of peripheral CaV2.2 calcium ion channels in skin play a unique role in the induction and maintenance of heat hypersensitivity in the CFA model of prolonged neuroinflammation, without accompanying effects on edema and mechanical hypersensitivity. Blocking peripheral CaV2.2 channel activity reduces local cytokine levels in hind paws injected with CFA including IL-6 and neutralizing IL-6 reduces CFA- induced heat hypersensitivity. Our studies define key signaling molecules that act locally in skin to trigger and maintain heat hypersensitivity during chronic neuroinflammation.

neuroscience↗

bioRxiv2023

Towards a Brighter Constellation: Multi-Organ Neuroimaging of Neural and Vascular Dynamics in the Spinal Cord and Brain

SignificancePain is comprised of a complex interaction between motor action and somatosensation that is dependent on dynamic interactions between the brain and spinal cord. This makes understanding pain particularly challenging as it involves rich interactions between many circuits (e.g., neural and vascular) and signaling cascades throughout the body. As such, experimentation on a single region may lead to an incomplete and potentially incorrect understanding of crucial underlying mechanisms. AimHere, we aimed to develop and validate new tools to enable detailed and extended observation of neural and vascular activity in the brain and spinal cord. The first key set of innovations were targeted to developing novel imaging hardware that addresses the many challenges of multi-site imaging. The second key set of innovations were targeted to enabling bioluminescent imaging, as this approach can address limitations of fluorescent microscopy including photobleaching, phototoxicity and decreased resolution due to scattering of excitation signals. ApproachWe designed 3D-printed brain and spinal cord implants to enable effective surgical implantations and optical access with wearable miniscopes or an open window (e.g., for one-or two-photon microscopy or optogenetic stimulation). We also tested the viability for bioluminescent imaging, and developed a novel modified miniscope optimized for these signals (BLmini). ResultsHere, we describe novel universal implants for acute and chronic simultaneous brain-spinal cord imaging and optical stimulation. We further describe successful imaging of bioluminescent signals in both foci, and a new miniscope, the BLmini, which has reduced weight, cost and form-factor relative to standard wearable miniscopes. ConclusionsThe combination of 3D printed implants, advanced imaging tools, and bioluminescence imaging techniques offers a new coalition of methods for understanding spinal cord-brain interactions. This work has the potential for use in future research into neuropathic pain and other sensory disorders and motor behavior.

bioengineering↗

bioRxiv2023

Interleukin-1α links peripheral CaV2.2 channel activation to rapid adaptive increases in heat sensitivity in skin

Neurons have the unique capacity to adapt output in response to changes in their environment. Within seconds, sensory nerve endings can become hypersensitive to stimuli in response to potentially damaging events. The underlying behavioral response is well studied, but several of the key signaling molecules that mediate sensory hypersensitivity remain unknown. We previously discovered that peripheral voltage-gated CaV2.2 channels in nerve endings in skin are essential for the rapid, transient increase in sensitivity to heat, but not to mechanical stimuli, that accompanies intradermal capsaicin. Here we report that the cytokine interleukin-1 (IL-1), an alarmin, is necessary and sufficient to trigger rapid heat and mechanical hypersensitivity in skin. Of 20 cytokines screened, only IL-1 was consistently detected in hind paw interstitial fluid in response to intradermal capsaicin and, similar to behavioral sensitivity to heat, IL-1 levels were also dependent on peripheral CaV2.2 channel activity. Neutralizing IL-1 in skin significantly reduced capsaicin-induced changes in hind paw sensitivity to radiant heat and mechanical stimulation. Intradermal IL-1 enhances behavioral responses to stimuli and, in culture, IL-1 enhances the responsiveness of Trpv1-expressing sensory neurons. Together, our data suggest that IL-1 is the key cytokine that underlies rapid and reversible neuroinflammatory responses in skin.

neuroscience↗

bioRxiv2023

Engineering luminopsins with improved coupling efficiencies

SignificanceLuminopsins (LMOs) are bioluminescent-optogenetic tools with a luciferase fused to an opsin that allow bimodal control of neurons by providing both optogenetic and chemogenetic access. Determining which design features contribute to the efficacy of LMOs will be beneficial for further improving LMOs for use in research. AimWe investigated the relative impact of luciferase brightness, opsin sensitivity, pairing of emission and absorption wavelength, and arrangement of moieties on the function of LMOs. ApproachWe quantified efficacy of LMOs through whole cell patch clamp recordings in HEK293 cells by determining coupling efficiency, the percentage of maximum LED induced photocurrent achieved with bioluminescent activation of an opsin. We confirmed key results by multielectrode array (MEAs) recordings in primary neurons. ResultsLuciferase brightness and opsin sensitivity had the most impact on the efficacy of LMOs, and N-terminal fusions of luciferases to opsins performed better than C-terminal and multi-terminal fusions. Precise paring of luciferase emission and opsin absorption spectra appeared to be less critical. ConclusionsWhole cell patch clamp recordings allowed us to quantify the impact of different characteristics of LMOs on their function. Our results suggest that coupling brighter bioluminescent sources to more sensitive opsins will improve LMO function. As bioluminescent activation of opsins is most likely based on Forster resonance energy transfer (FRET), the most effective strategy for improving LMOs further will be molecular evolution of luciferase-fluorescent protein-opsin fusions.

molecular biology↗

bioRxiv2023

ω-Phonetoxins inhibit voltage-gated calcium CaV2.2 ion channel splice isoforms of dorsal root ganglia

Cell-specific alternative splicing of Cacna1b pre-mRNA generates functionally distinct voltage-gated CaV2.2 channels. CaV2.2 channels mediate the release of glutamate from nociceptor termini in the dorsal horn spinal cord and they are implicated in chronic pain. One alternatively spliced exon in Cacna1b, e37a, is highly expressed in dorsal root ganglia, relative to other regions of the nervous system, and it is particularly important in inflammatory hyperalgesia. Here we studied the effects of two {omega}-phonetoxins, PnTx3-4 and Ph1{beta}, derived from the spider Phoneutria nigriventer on CaV2.2 channel isoforms of dorsal root ganglia (CaV2.2 e37a and CaV2.2 e37b). Both PnTx3-4 and Ph1{beta} are known to have analgesic effects in rodent models of pain and to inhibit CaV2.2 channels. CaV2.2 e37a and CaV2.2 e37b isoforms expressed in a mammalian cell line were inhibited by PnTx3-4 and Ph1{beta} with similar potency and with similar timecourse, although CaV2.2 e37a currents were slightly, but consistently more sensitive to toxin inhibition compared to CaV2.2 e37b. The inhibitory effects of PnTx3-4 and Ph1{beta} on CaV2.2-e37a and CaV2.2-e37b channels were voltage-dependent, and both occlude the inhibitory effects of {omega}-conotoxin GVIA, consistent with a common site of action. The potency of PnTx3-4 and Ph1{beta} on both major splice isoforms in dorsal root ganglia constribute to understanding the analgesic actions of these {omega}-phonetoxins.

neuroscience↗

bioRxiv2023

A Bioluminescent Activity Dependent (BLADe) Platform for Converting Neuronal Activity to Photoreceptor Activation

Genetically encoded sensors and actuators have advanced the ability to observe and manipulate cellular activity, yet few non-invasive strategies enable cells to directly couple their intracellular states to user-defined outputs. We promote a bioluminescent activity-dependent (BLADe) platform that facilitates programmable feedback through genetically encoded light generation. Using calcium (Ca{superscript 2}) flux as a model, we engineered a Ca{superscript 2}-dependent luciferase that functions as an activity-gated light source capable of photoactivating light-sensing actuators. As an initial demonstration of the versatility of this platform we present two separate use cases in neurons. In the first application, the presence of luciferin triggers Ca{superscript 2} dependent local illumination that provides activity dependent gene expression by activating a light-sensitive transcription factor. In the second application, neuronal activity-driven Ca{superscript 2} fluctuations via locally generated bioluminescence control neural dynamics through opsin activation in single cells, populations and intact tissue. BLADe can be expanded to couple any signal that bioluminescent enzymes can be engineered to detect with the wide variety of photosensing actuators. This modular strategy of coupling an activity dependent light emitter to a light sensing actuator offers, in principle, a generalizable framework for state dependent cell-autonomous control across biological systems.

neuroscience↗

bioRxiv2023

CaBLAM! A high-contrast bioluminescent Ca2+ indicator derived from an engineered Oplophorus gracilirostris luciferase

Measuring ongoing cellular activity is essential to understanding the dynamic functions of biological organisms. The most popular current approach is imaging fluorescence-based genetically encoded Ca2+ indicators (GECIs). While fluorescent probes are useful in many contexts, bioluminescence-based GECIs--probes that generate light through oxidation of a small-molecule by a luciferase or photoprotein--have several distinct advantages. Because bioluminescent (BL) GECIs do not use the bright extrinsic excitation light required for fluorescence, BL GECIs do not photobleach, do not suffer from nonspecific autofluorescent background, and do not cause phototoxicity. Further, BL GECIs can be applied in contexts where directly shining photons on an imaging target is not possible. Despite these advantages, the use of BL GECIs has to date been limited by their small changes in bioluminescence intensity, high baseline signal at resting Ca2+ concentrations, and suboptimal Ca2+ affinities. Here, we describe a new BL GECI, CaBLAM (Ca2+ BioLuminescence Activity Monitor), that displays much higher dynamic range than previous BL GECIs and has a Ca2+ affinity suitable for capturing physiological changes in cytosolic Ca2+ concentration. With these improvements, CaBLAM captures single-cell and subcellular resolution activity at high frame rates in cultured neurons and in vivo, and allows multi-hour recordings in mice and behaving zebrafish. This new advance provides a robust alternative to traditional fluorescent GECIs that can enable or enhance imaging across many experimental conditions.

neuroscience↗

bioRxiv2023

A FRET-based excitatory luminopsin with improved efficacy of bioluminescence-driven activation

SignificanceBioluminescent optogenetics (BL-OG) offers a unique and powerful approach to manipulate neural activity both opto- and chemogenetically using a single actuator molecule (a LuMinOpsin, LMO). AimTo further enhance the utility of BL-OG by improving the efficacy of chemogenetic (bioluminescence- driven) LMO activation. ApproachWe developed novel luciferases optimized for Forster resonance energy transfer (FRET) when fused to the fluorescent protein mNeonGreen, generating bright bioluminescent (BL) emitters spectrally tuned to Volvox Channelrhodopsin 1 (VChR1). ResultsA new LMO generated from this approach (LMO7) showed significantly stronger BL-driven opsin activation compared to previous and other new variants. We extensively benchmarked LMO7 against LMO3 (current standard), and found significantly stronger neuronal activity modulation ex vivo and in vivo, and efficient modulation of behavior. ConclusionsWe report a robust new option for achieving multiple modes of control in a single actuator, and a promising engineering strategy for continued improvement of BL-OG.

neuroscience↗

bioRxiv2023

Up-regulation of cholesterol synthesis pathways and limited neurodegeneration in a knock-in Sod1 mutant mouse model of ALS.

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disorder affecting brain and spinal cord motor neurons. Mutations in the copper/zinc superoxide dismutase gene (SOD1) are associated with [~]20% of inherited and 1-2% of sporadic ALS cases. Much has been learned from mice expressing transgenic copies of mutant SOD1, which typically involve high-level transgene expression, thereby differing from ALS patients expressing one mutant gene copy. To generate a model that more closely represents patient gene expression, we created a knock-in point mutation (G85R, a human ALS-causing mutation) in the endogenous mouse Sod1 gene, leading to mutant SOD1G85R protein expression. Heterozygous Sod1G85R mutant mice resemble wild type, whereas homozygous mutants have reduced body weight and lifespan, a mild neurodegenerative phenotype, and express very low mutant SOD1 protein levels with no detectable SOD1 activity. Homozygous mutants exhibit partial neuromuscular junction denervation at 3-4 months of age. Spinal cord motor neuron transcriptome analyses of homozygous Sod1G85R mice revealed up-regulation of cholesterol synthesis pathway genes compared to wild type. Transcriptome and phenotypic features of these mice are similar to Sod1 knock-out mice, suggesting the Sod1G85R phenotype is largely driven by loss of SOD1 function. By contrast, cholesterol synthesis genes are down-regulated in severely affected human TgSOD1G93A transgenic mice at 4 months. Our analyses implicate dysregulation of cholesterol or related lipid pathway genes in ALS pathogenesis. The Sod1G85R knock-in mouse is a useful ALS model to examine the importance of SOD1 activity in control of cholesterol homeostasis and motor neuron survival. SIGNIFICANCE STATEMENTAmyotrophic lateral sclerosis is a devastating disease involving the progressive loss of motor neurons and motor function for which there is currently no cure. Understanding biological mechanisms leading to motor neuron death is critical for developing new treatments. Using a new knock-in mutant mouse model carrying a Sod1 mutation that causes ALS in patients, and in the mouse, causes a limited neurodegenerative phenotype similar to Sod1 loss-of-function, we show that cholesterol synthesis pathway genes are up-regulated in mutant motor neurons, whereas the same genes are down-regulated in transgenic SOD1 mice with a severe phenotype. Our data implicate dysregulation of cholesterol or other related lipid genes in ALS pathogenesis and provide new insights that could contribute to strategies for disease intervention.

neuroscience↗

bioRxiv2021

Selective Control of Synaptically-Connected Circuit Elements by All-Optical Synapses

Understanding percepts, engrams and actions requires methods for selectively modulating synaptic communication between specific subsets of interconnected cells. Here, we develop an approach to control synaptically connected elements using bioluminescent light: Luciferase-generated light, originating from a presynaptic axon terminal, modulates an opsin in its postsynaptic target. Vesicular-localized luciferase is released into the synaptic cleft in response to presynaptic activity, creating a real-time Optical Synapse. Light production is under experimenter-control by introduction of the small molecule luciferin. Signal transmission across this optical synapse is temporally defined by the presence of both the luciferin and presynaptic activity. We validate synaptic Interluminescence by multi-electrode recording in cultured neurons and in mice in vivo. Interluminescence represents a powerful approach to achieve synapse-specific and activity-dependent circuit control during behavior in vivo.

neuroscience↗

bioRxiv2020

Peripheral voltage-gated calcium channels in skin are essential for transient neurogenic thermal hyperalgesia in mice

Voltage-gated CaV2.2 calcium channels are expressed in nociceptors, at pre-synaptic terminals, soma, and axons. CaV2.2 channel inhibitors applied to the spinal cord relieve pain in humans and rodents, especially during pathological pain, but a biological function of nociceptor CaV2.2 channels in processing of nociception, outside pre-synaptic terminals, is not explored. Here, we demonstrate that functional CaV2.2 channels in skin are required for thermal hyperalgesia following intraplantar capsaicin exposure. We provide evidence that CaV2.2 channels at nociceptor free endings release inflammatory signals, ATP and IL-1{beta}. We assess the role of CaV2.2 splice isoforms to capsaicin-induced hyperalgesia measured by thermal and mechanical stimuli. Our data reveal a critical role for peripheral CaV2.2 channels in skin in neurogenic thermal hyperalgesia but not in mechanical hypersensitivity. Inhibition, or the complete lack, of peripheral CaV2.2 channels blunts the hyperalgesia response in vivo.

neuroscience↗

bioRxiv2020

Miniaturized Devices for Bioluminescence Imaging in Freely Behaving Animals

Fluorescence miniature microscopy in vivo has recently proven a major advance, enabling cellular imaging in freely behaving animals. However, fluorescence imaging suffers from autofluorescence, phototoxicity, photobleaching and non-homogeneous illumination artifacts. These factors limit the quality and time course of data collection. Bioluminescence provides an alternative kind of activity-dependent light indicator. Bioluminescent calcium indicators do not require light input, instead generating photons through chemiluminescence. As such, limitations inherent to the requirement for light presentation are eliminated. Further, bioluminescent indicators also do not require excitation light optics: the removal of this component should make lighter and lower cost microscope with fewer assembly parts. While there has been significant recent progress in making brighter and faster bioluminescence indicators, parallel advances in imaging hardware have not yet been realized. A hardware challenge is that despite potentially higher signal-to-noise of bioluminescence, the signal strength is lower than that of fluorescence. An open question we address in this report is whether fluorescent miniature microscopes can be rendered sensitive enough to detect bioluminescence. We demonstrate this possibility in vitro and in vivo by implementing optimizations of the UCLA fluorescent miniscope. These optimizations yielded a miniscope (BLmini) which is 22% lighter in weight, has 45% fewer components, is up to 58% less expensive, offers up to 15 times stronger signal (as dichroic filtering is not required) and is sensitive enough to capture spatiotemporal dynamics of bioluminescence in the brain with a signal-to-noise ratio of 34 dB.

bioengineering↗

bioRxiv2019

Cell-specific exon methylation and CTCF binding in neurons regulates calcium ion channel splicing and function

Cell-specific alternative splicing modulates myriad cell functions and this process is disrupted in disease. The mechanisms governing alternative splicing are known for relatively few genes and typically focus on RNA splicing factors. In sensory neurons, cell-specific alternative splicing of the presynaptic voltage-gated calcium channel Cacna1b gene modulates opioid sensitivity. How this splicing is regulated has remained unknown. We find that cell-specific exon DNA hypomethylation permits binding of CTCF, the master regulator of chromatin structure in mammals, which, in turn, controls splicing in noxious heat-sensing nociceptors. Hypomethylation of an alternative exon specifically in nociceptors allows for CTCF binding, and expression of CaV2.2 channels with increased opioid sensitivity. Following nerve injury, exon methylation is increased, and splicing is disrupted. Our studies define the molecular mechanisms of cell-specific alternative splicing of a functionally validated exon in normal and disease states - and reveal a potential target for the treatment of chronic pain. HighlightsO_LIThe molecular basis of cell-specific splicing of a synaptic calcium channel gene. C_LIO_LISplicing controlled by cell-specific exon hypomethylation and CTCF binding. C_LIO_LIPeripheral nerve injury disrupts exon hypomethylation and splicing. C_LIO_LITargeted demethylation of exon by dCAS9-TET modifies alternative splicing. C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=158 SRC="FIGDIR/small/876185v2_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@11b592eorg.highwire.dtl.DTLVardef@7c0eddorg.highwire.dtl.DTLVardef@b403bborg.highwire.dtl.DTLVardef@611882_HPS_FORMAT_FIGEXP M_FIG Cell-specific epigenetic modifications in a synaptic calcium ion channel gene controls cell-specific splicing in normal and neuropathic pain. In naive animals, in most neurons, Cacna1b e37a locus is hipermethylated (5-mC) and CTCF does not bind this locus. During splicing, e37a is skipped and Cacna1b mRNAs include e37b. In contrast, in Trpv1-lineage neurons, Cacna1b e37a locus is hypomethylated and is permissive for CTCF binding. CTCF promotes e37a inclusion and both Cacna1b e37a and e37b mRNAs are expressed. E37a confers strong sensitivity to the Cav2.2 channel to inhibition by -opioid receptors (OR). Morphine is more effective at inhibiting e37a-containing Cav2.2 channels. After peripheral nerve injury that results in pathological pain, methylation level of Cacna1b e37a locus is increased, CTCF binding is impaired, and Cacna1b e37a mRNA levels are decreased. This disrupted splicing pattern is associated with reduced efficacy of morphine in vivo. C_FIG

neuroscience↗

bioRxiv2018

Circuit dysfunction in SOD1-ALS model first detected in sensory feedback prior to motor neuron degeneration is alleviated by BMP signaling

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease whose origin and underlying cellular defects are still not fully understood. While motor neuron degeneration is the signature feature of ALS, it is not yet clear if motor neurons, or other cells of the motor circuit, are the site of disease initiation. To better understand the contribution of multiple cell types in ALS, we made use of a Drosophila Sod1G85R knock-in model, in which all cells harbor the disease allele. End-stage dSod1G85R animals exhibit severe motor deficits with clear degeneration of motor neurons. Interestingly, earlier in dSod1G85R larvae motor function is also compromised, but their motor neurons exhibit only subtle morphological and electrophysiological changes, that are unlikely to cause the observed decrease in locomotion. We analyzed the intact motor circuit and identified a defect in sensory feedback that likely accounts for the altered motor activity of dSod1G85R. Furthermore, we found that the cell-autonomous activation of BMP signaling in proprioceptor sensory neurons that relay the contractile status of muscles back to the central nerve cord, is able to completely rescue early stage motor defects and partially rescue late stage motor function to extend lifespan. Identifying a defect in sensory feedback as a potential initiating event in ALS motor dysfunction, coupled with the ability of modified proprioceptors to alleviate such motor deficits, underscores the critical role that non-motor neurons play in disease progression and highlights their potential as a site to identify early-stage ALS biomarkers and for therapeutic intervention.\n\nSignificance StatementAt diagnosis, many cellular processes are already disrupted in the ALS patient. Identifying the initiating cellular events is critical for achieving an earlier diagnosis in order to slow or prevent disease progression. Our findings indicate that neurons relaying sensory information underlie early stage motor deficits in a Drosophila knock-in model of ALS that best replicates gene dosage in familial ALS (fALS). Importantly, studies on intact motor circuits revealed defects in sensory feedback before evidence of motor neuron degeneration. These findings strengthen our understanding of how neural circuit dysfunctions lead to neurodegeneration and coupled with our demonstration that activation of BMP signaling in proprioceptors alleviates both early and late motor dysfunction, underscores the importance of considering non-motor neurons as therapeutic targets.

neuroscience↗