Biology subjects

Suh, J.

Publications and source records attributed to Suh, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Stressor Identity Shapes Reactivity To Subsequent Stress

Extensive work has established that exposure to a single acute stressor can have profound impacts on future reactivity to new stressors, including enhanced acquisition of new fear. The impact of stressor type on development of stress sensitization, however, remains unclear. We investigated whether fundamentally different acute stressors (shock, social defeat, or restraint stress) differ in ability to sensitize acquisition of a new, contextually distinct fear memory in adult male mice two weeks following stress exposure. Stressor subtype differentially sensitized new fear learning; specifically, shock and social defeat - but not restraint stress - led to enhanced recall of a new shock-paired fear memory. We also compared how stressor subtypes differentially engage the brain-periphery interactions that regulate stress responsivity. Notably, restraint stress, which did not lead to fear sensitization to foot shock, drove similar or even greater corticosterone release than other stressors, suggesting that the neuroendocrine response to the original stressor is dissociable from development of a behavioural fear sensitization response. Using the immediate-early gene FOS as a marker of neural activity, all conditions - including the context-only control condition - activated a similar number of neurons in the basolateral amygdala. In contrast, only stressful conditions activated the paraventricular nucleus of the hypothalamus, and restraint stress selectively spared activation of the dorsal hippocampus. These data collectively suggest that future responses to stress depend critically on the identity of previously experienced stressors, rather than simply on prior exposure to stress, establishing a powerful comparative model for investigating the specific mechanisms underlying stress-enhanced fear learning.

neuroscience↗

bioRxiv2026

Progranulin deficiency perturbs lipid metabolism in white matter microglia

Progranulin (PGRN) deficiency is a common hallmark in frontotemporal dementia (FTD) patients with granulin (GRN) mutations (FTD-GRN). Previous studies by our group and others have observed that reduced PGRN perturbs lysosomal function and microglial activation, which is believed to accelerate neurodegeneration in FTD-GRN patients. Lysosomal function is intrinsically linked to lipid metabolism, and evidence suggests that GRN deficiency can alter lipid profiles in the brain. Unfortunately, studies to date have focused on whole brain or cortical extracts, limiting our ability to assess cell type-dependent changes in lipid metabolism under disease conditions. Here, we employed lipidomic analysis specifically within the pontine microglia of Grn knock-out (KO) mice, a cell population that was previously linked to disease phenotypes in this model. We observed a significant reduction in the endolysosomal lipid bis(monoacylglycero)phosphate (BMP) and the lipid metabolite phosphatidylethanolamine (PE); these microglial-specific lipid alterations mirror previous whole-brain findings, suggesting that similar changes may occur across multiple cell types in the brain. We also detected a significant increase in the myelin-composing factor galactosylceramide (GalCer), which may reflect an aberrant accumulation of myelin debris within microglia that arises due to defective lysosomal clearance. Notably, lipid perturbations were exacerbated with age within Grn KO microglia, suggesting that changes in lipid metabolism are both age- and genotype-dependent in this model. Together, our results support our hypothesis that PGRN acts as a master regulator of critical microglial processes - including lysosomal function, lipid metabolism, and the regulation of myelination - in an age-dependent manner.

neuroscience↗

bioRxiv2026

Fine mapping of PTSD GWAS reveals a role for amygdala Foxp2 in regulation of fear and threat responses

Post-traumatic Stress Disorder (PTSD) is a debilitating psychiatric condition caused by severe trauma exposure and characterized by ongoing dysregulation of fear processing, hyperarousal, and amygdala activation, but with limited effective treatments. Recent large-scale genome-wide association studies (GWAS) of PTSD have identified the transcription factor FOXP2 as a highly-significant, top putative risk gene. Both fine-mapping of the PTSD GWAS with amygdala-specific expression quantitative trait loci (eQTL) data, and transcriptome-wide association analyses, show that altered expression of FOXP2 is associated with increased PTSD risk. In vertebrates, FOXP2 mRNA is most densely expressed in the intercalated cells (ITCs) of the amygdala. ITC neurons receive excitatory input from external regulatory and sensory brain regions, as well as the basolateral amygdala, and send inhibitory projections to the central amygdala, which regulates downstream fear responses. While ITCs are critical for conditioned fear acquisition and extinction, the role of the FOXP2 gene in modulating fear-related behaviors remains unknown. Here, we used complementary bioinformatic, molecular, circuit, behavioral, and electrophysiological approaches to characterize the function of mouse (Foxp2) and human (FOXP2) orthologs in amygdala-mediated fear learning. To assess Foxp2 function in vivo, we first used shRNA-mediated knockdown (KD) of Foxp2 in ITC neurons of adult mice. Targeted Foxp2 KD robustly and significantly reduced freezing (threat/fear expression) during and after auditory fear conditioning. Whole-cell recordings from individual ITC neurons revealed that Foxp2 KD increased their intrinsic membrane excitability and action potential frequency, consistent with hypothesized enhanced inhibitory output to the central amygdala and thus reduced fear expression. This hyperexcitability was associated with reduced potassium channel conductance. Bulk RNA sequencing (RNA-seq) of mouse amygdala after ITC Foxp2 KD confirmed decreased potassium channel transcription and revealed broader Foxp2-dependent regulation of multiple genes implicated in fear learning, including Wnt, Crh (which encodes corticotropin-releasing hormone), and neurokinin signaling pathways. Consistent with these findings, bulk RNA-seq of medial amygdala postmortem tissue from humans with PTSD versus neurotypical controls showed decreased potassium channel transcription in samples with low FOXP2 expression. Downstream transcriptional changes following Foxp2 KD in the mouse amygdala also showed marked enrichment of genes identified in PTSD risk loci from the largest PTSD GWAS to date. Specifically, downregulated genes were enriched for mouse orthologs of Tier 1 PTSD GWAS risk genes. This enrichment appears to reflect subcortical Foxp2 signaling within the amygdala, driven predominantly by decreased expression of genes lacking promoter-anchored chromatin loops. This finding suggests that Foxp2 may directly bind regulatory elements of multiple top PTSD risk genes, acting as a key regulatory node for fear-related pathways in the amygdala. Collectively, our findings establish FOXP2 as a central transcriptional regulator of fear-related gene networks in the amygdala and potential regulatory hub for PTSD genetic risk.

neuroscience↗

bioRxiv2026

Acute Ethanol Exposure Induces Stage-Specific Bioenergetic, Mitochondrial and Neurodevelopmental Transcriptional Remodeling in Human Forebrain Progenitors

Prenatal alcohol exposure (PAE) is associated with long-term neurodevelopmental risk, yet how neuronal progenitor metabolism responds to alcohol across developmental stages remains unclear. Here, we integrated brain-isoform-focused analysis of public datasets with targeted transcriptional, translational, and functional mitochondrial assessments in human iPSC-derived cortical progenitor models representing distinct bioenergetic states. Re-analysis of prior PAE studies revealed broad metabolic gene downregulation in embryonic systems, whereas neurodevelopmental models showed limited and non-coherent transcriptional signatures. In vitro, acute ethanol exposure (AEE) induced stage-dependent transcriptional remodeling in iPSC-derived neuronal progenitor cells. Early progenitors exhibited selective upregulation of mitochondrial-associated transcripts alongside increased neuronal lineage markers. In contrast, late progenitors showed broader increases in glycolytic, lipid, and mitochondrial gene expression. Despite these transcriptional changes, mitochondrial ATP production and mitochondrial protein abundance remained unchanged in both models with altered dynamics being restricted to late progenitors. These findings indicate that ethanol exposure is associated with developmental stage-dependent neuronal remodeling of bioenergetic genes. Measurements of mitochondrial-neural frameworks after AEE showed no major alterations in either model. Overall, our results reveal a dissociation between transcriptional, translational, and functional bioenergetic outputs in models of early human neurodevelopment and highlight that transcriptional alterations of mitochondria and cellular bioenergetics under AEE should be interpreted in the context of developmental stage rather than in isolation as evidence of energetic dysfunction.

neuroscience↗

bioRxiv2026

Biological nitrification inhibition compromises the soil methane sink

Biological nitrification inhibition (BNI) is a plant-mediated process that suppresses nitrification and is widely considered beneficial for reducing nitrous oxide emissions. Here, we show that BNI compounds also inhibit methane oxidation by methanotrophic bacteria, revealing a previously unrecognized trade-off in greenhouse gas regulation. Across soil bioreactor systems and pure cultures of both Type I and Type II methanotrophs, BNI compounds consistently suppressed methane oxidation activity. Kinetic analyses indicated an uncompetitive-like inhibition pattern, characterized by concurrent decreases in Vmax and Km, while reversibility assays showed that inhibition was not associated with loss of cellular viability. Experiments under copper-replete and copper-depleted conditions further showed that inhibition is predominantly associated with particulate methane monooxygenase (pMMO). Transcriptomic analyses demonstrated compound-specific responses, including suppression of methane oxidation pathways and differential regulation of stress-associated genes. These findings suggest that BNI-mediated inhibition of methane oxidation may offset reductions in nitrous oxide emissions, with implications for predicting net greenhouse gas fluxes in agricultural and wetland ecosystems. Incorporating BNI effects into biogeochemical models will be critical for accurately evaluating their role in the global methane budget.

microbiology↗

bioRxiv2025

A human forebrain organoid model phenocopies dysregulated RNA and protein homeostasis in ALS/FTD-associated TDP-43 proteinopathies

TAR DNA-binding protein 43 (TDP-43) proteinopathy is a defining pathological feature of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), yet the downstream molecular events linking TDP-43 dysfunction to neurodegeneration remain incompletely understood. Here, we model TDP-43 proteinopathy by introducing the ALS/FTD-associated TARDBP K181E mutation into human induced pluripotent stem cells and differentiating them into three-dimensional forebrain organoids. Organoids carrying the K181E mutation exhibit spontaneous TDP-43 hyperphosphorylation, cytoplasmic p-TDP43 accumulation, RNA dysregulation, pro-inflammatory signaling, and activation of apoptotic pathways without TDP-43 overexpression or external stress. Single-cell transcriptomics and enhanced crosslinking immunoprecipitation reveal that the K181E mutation alters TDP-43 RNA-binding specificity, causing widespread RNA mis-splicing including cryptic exon inclusion. Among affected targets, we identify cryptic exon inclusion in the transcription factor PRDM2. PRDM2 cryptic exon-derived peptide immunoreactivity was detected in ALS spinal motor neurons and associated with p-TDP-43 pathology. These findings identify PRDM2 mis-splicing as a candidate downstream event linking TDP-43 dysfunction relevant to ALS and FTD. One sentence summaryHuman brain organoids reveal how mutant TDP-43 disrupts RNA processing and causes neuronal stress.

neuroscience↗

bioRxiv2025

Effects of the Neutral CB1 Receptor Antagonist AM6527 on Spontaneous, Consummatory, and Motivated Behavior in Mice

RationaleThe cannabinoid type-1 receptor (CB1R) signaling pathway plays a central role in regulating motivational and feeding behaviors. Neutral CB1R antagonists represent a promising therapeutic class with potentially fewer adverse effects than inverse agonists, yet their behavioral effects remain incompletely characterized. ObjectivesWe investigated the behavioral profile of AM6527, orally bioavailable neutral CB1R antagonist, across naturalistic and operant paradigms in male mice. To evaluate dopaminergic involvement in AM6527s effects, we employed several pharmacological interventions. ResultsUsing machine learning-based Motion-Sequencing (MoSeq), which parses spontaneous behavior into sub-second syllables, we found that AM6527 did not affect overall speed in an open field, however, it increased the self-directed behaviors and reduced specific locomotor syllables at the highest dose tested. In a naturalistic reward consumption paradigm, AM6527 produced a dose-dependent reduction in milk intake. Operant conditioning paradigms revealed robust suppression of motivated responding on fixed ratio-3 and progressive ratio (PR) schedules for palatable milk reward, with the greatest impact on high-baseline performers under PR conditions. To understand the dopaminergic involvement, we co-administered dopaminergic drugs (targeting D1R, D2R, or dopamine transporter) which resulted in partial rescue of operant responding, indicating dopaminergic and non-dopaminergic contributions to AM6527s observed behavioral effects. ConclusionOur findings suggest that neutral CB1R antagonism suppresses consummatory and motivated behaviors via dopamine-dependent and -independent mechanisms. By leveraging sub-second behavioral analysis with MoSeq, we further reveal distinct changes in spontaneous behavior, underscoring the relevance of CB-based treatments for maladaptive appetitive and motivational states in both psychiatric and metabolic disorder.

neuroscience↗

bioRxiv2025

GPR34 regulates microglia state and loss-of-function rescues TREM2 metabolic dysfunction

Microglia are implicated in modifying neurodegenerative disease risk in the central nervous system (CNS). GPR34 is a microglia-enriched G-protein coupled receptor that detects cytotoxic lipids upregulated in Alzheimers Disease (AD). Since dysregulated lipid metabolism occurs in disease, we hypothesized GPR34 could act with other lipid sensors, such as TREM2, to regulate microglial function. Here, we report that GPR34 knockout (KO) rescues dysregulated cholesterol metabolism in TREM2 KO iPSC-derived microglia (iMG) and alone promotes fatty acid catabolism without the proton leak observed in TREM2 KO. Loss of GPR34 downregulated ERK signaling, while its agonism promoted interaction with and activation of ERK. In healthy and amyloid mouse models, Gpr34 KO accelerated the conversion of homeostatic microglia to disease-associated microglia (DAM) states. Additionally, in Gpr34 KO amyloid mouse brain, the frequency of large plaques was increased compared to WT, indicating that Gpr34 KO microglia may promote amyloid aggregation. Overall, our data suggest GPR34 as a therapeutic target for modulating microglial function to slow AD progression.

neuroscience↗

bioRxiv2024

Vinculin Y822 phosphorylation regulates cardiomyocyte adhesion dynamics and adherens junction maturation in the heart

In the heart, cell-matrix and cell-cell adhesions reorganize in response to increased cardiac demand and growth to promote cardiomyocyte maturation. Vinculin, a mechanosensitive adaptor protein, links filamentous actin to cell-matrix and cell-cell adhesions and is thus positioned to regulate adhesion reorganization. However, how the two adhesion systems are coordinated in the heart, and the role of vinculin in this process is poorly understood. Here, we define the role of vinculin phosphorylation at tyrosine residue 822 (pY822) in cardiomyocyte adhesion and heart function. We found that pY822 correlated with dynamic junction remodeling in the developing heart but was lost as junctions matured postnatally. We then mutated Y822 to phenylalanine (Y822F) in the mouse to determine pY822 function in vivo. Homozygous mutant Vcl Y822F mice were viable and exhibited normal cardiac function at ten weeks of age; however, cardiac dysfunction was observed at 28 weeks. Vinculin and adherens junction proteins were reduced at cardiomyocyte junctions in Y822F hearts. In contrast, 5/{beta}1 integrin and fibronectin increased along the lateral border of Y822F cardiomyocytes. Our results demonstrate that vinculin Y822 phosphorylation regulates the balance between cadherin and integrin adhesion organization, highlighting the importance of post-translational modification in modulating vinculin function in heart physiology.

cell biology↗

bioRxiv2024

Cis-regulatory elements driving motor neuron-restricted viral payload expression within the mammalian spinal cord

Spinal motor neuron (MN) dysfunction is the cause of a number of clinically significant movement disorders. Despite the recent approval of gene therapeutics targeting these MN-related disorders, there are no viral delivery mechanisms that achieve MN-restricted transgene expression. In this study, chromatin accessibility profiling of genetically defined mouse MNs was used to identify candidate cis-regulatory elements (CREs) capable of driving MN-selective gene expression. Subsequent testing of these candidates identified two CREs that confer MN-selective gene expression in the spinal cord as well as reduced off-target expression in dorsal root ganglia. Within one of these candidate elements, we identified a compact core transcription factor (TF)-binding region that drives MN-selective gene expression. Finally, we demonstrate that selective spinal cord expression of this mouse CRE is preserved in non-human primates. These findings suggest that the generation of cell-type-selective viral reagents, in which cell-type-selective CREs drive restricted gene expression, will be valuable research tools in mice and other mammalian species, with potentially significant therapeutic value in humans. SIGNIFICANCE STATEMENTMotor neurons transduce the motor outputs of nervous system activity to muscle and are the vulnerable neurons in a number of clinically significant degenerative conditions, including spinal muscular atrophy and amyotrophic lateral sclerosis. A recent strategy for treating motor neuron degenerative diseases has been to use viruses to introduce genes into motor neurons to inhibit the degenerative process. However, we still lack viral reagents that promote gene expression in motor neurons without potentially toxic off-target expression in other cell types. Our study identifies cis-regulatory elements capable of conferring motor neuron-selective transgene expression in a viral context. These findings have important implications for future gene therapeutics for motor neuron-related disorders.

neuroscience↗

bioRxiv2024

Enhanced Suppression of Stenotrophomonas maltophilia by a Three-Phage Cocktail: Genomic Insights and Kinetic Profiling

In our era of rising antibiotic resistance, Stenotrophomonas maltophilia (STM) is an understudied, gram-negative, aerobic bacterium widespread in the environment and increasingly causing opportunistic infections. Treating STM infections remains difficult, leading to an increase in disease severity and higher hospitalization rates in people with Cystic Fibrosis (pwCF), cancer, and other immunocompromised health conditions. The lack of effective antibiotics has led to renewed interest in phage therapy; however, there is a need for well-characterized phages. In response to an oncology patient with a respiratory infection, we collected 18 phages from Southern California wastewater influent that exhibit different plaque morphology against STM host strain B28B, cultivated from a blood sample. Here, we characterize the genomes and life cycle kinetics of our STM phage collection. We hypothesize that genetically distinct phages give rise to unique lytic life cycles that can enhance bacterial killing when combined into a phage cocktail compared to the individual phages alone. We identified three genetically distinct clusters of phages, and a representative from each group was screened for potential therapeutic use and investigated for infection kinetics. The results demonstrated that the three-phage cocktail significantly suppressed bacterial growth compared to individual phages when observed for 48 hours. We also assessed the lytic impacts of our three-phage cocktail against a collection of 46 STM strains to determine if a multi-phage cocktail can expand the host range of individual phages. Our phages remained strain-specific and infect >50% of tested strains. The multi-phage cocktail maintains bacterial growth suppression and prevents the emergence of phage-resistant strains throughout our 40-hour assay. These findings suggest specialized phage cocktails may be an effective avenue of treatment for recalcitrant STM infections resistant to current antibiotics. IMPORTANCEPhage therapy could provide a vital strategy in the fight against antimicrobial resistance (AMR) bacterial infections; however, significant knowledge gaps remain. This study investigates phage cocktail development for the opportunistic pathogen Stenotrophomonas maltophilia (STM). Our findings contribute novel phages, their lytic characteristics, and limitations when exposed to an array of clinically relevant STM strains. Eighteen bacteriophages were isolated from wastewater influent from Escondido, California, and subjected to genomic analysis. We investigated genetically distinct phages to establish their infection kinetics and developed them into a phage cocktail. Our findings suggest that a genetically distinct STM phage cocktail provides an effective strategy for bacterial suppression of host strain B28B and five other clinically relevant STM strains. Phage therapy against STM remains poorly understood, as only 39 phages have been previously isolated. Future research into the underlying mechanism of how phage cocktails overwhelm the host bacteria will provide essential information that could aid in optimizing phage applications and impact alternative treatment options.

microbiology↗

bioRxiv2024

A Metagenomic Approach Does Not Elucidate Uremic Toxin Levels in Hemodialysis Patients.

Blood levels of uremic molecules generated through gut microbial metabolism are associated with disease risk, reduced quality of life, and mortality in patients with renal insufficiency. Modulation of the microbiome may offer therapeutic potential. ObjectiveThis study aimed to elucidate the relationships between fecal microbiome and serum levels of targeted uremic molecules in adults undergoing hemodialysis and, secondarily, the role of relative macronutrient substrate availability. MethodsFecal microbiota was profiled by whole metagenome sequencing, serum p-cresyl sulfate (CS), indoxyl sulfate (IS), phenylacetylglutamine (PAG), and trimethylamine N-oxide (TMAO) were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and dietary intake was assessed by three multipass-method 24-hr recalls. ResultsDifferences in gut microbiome associated with serum uremic toxin levels were not detected. Instead, the relative substrate availability for the microbiota, using dietary protein-to-fiber ratio, was significantly associated with uremia. Serum levels of IS (multivariate linear model, p=0.042) and TMAO (p=0.032) were positively associated with dietary protein-to-fiber ratio, but not CS (p=0.096) and PAG (p=0.44). ConclusionThe lack of association of fecal microbiome with serum uremic toxins suggests that hemodialysis patients possess sufficient microbial enzymatic capacity for the synthesis of these molecules and that, instead, microbially available substrate, protein vs. fiber, may be the primary driver of production.

microbiology↗

bioRxiv2024

Amygdala circuit mechanisms underlying alcohol seeking

Alcohol seeking during abstinence is mediated in part by strong associations between the pharmacological effects of alcohol and the environment within which alcohol is administered. The amygdala, particularly the basolateral amygdala (BLA), is a key neural substrate of environmental cue and reward associations since it is involved in associative learning and memory recall. However, we still lack a clear understanding of how the activity of molecularly distinct BLA neurons is affected by alcohol and encodes information that drives environmental cue-dependent, alcohol-related behaviors. We previously demonstrated that a subset of BLA neurons which express the CaMKII and Thy1 markers project preferentially to the nucleus accumbens (NAcc), rather than the central amygdala; and these neurons mediate fear inhibition rather than fear acquisition or expression, suggesting a specific role in positive valence processing. We now demonstrate that Pavlovian conditioning with alcohol administration increases the activity of these Thy1-expressing (Thy1+) excitatory neurons in mouse BLA, which is necessary for the conditioned appetitive response. In vivo calcium imaging indicates that the temporal activity profile of these neurons is also correlated with alcohol seeking behavior in response to environmental cues. Optogenetic inhibition of BLA Thy1+ neuronal activity disrupts both the formation and recall of alcohol conditioned place preference. Furthermore, selective axonal inhibition of BLA-Thy1+ neurons reveals that the activity of their NAcc and prefrontal cortex (PFC) projections are differentially necessary for alcohol cue association vs. recall, respectively. Together, these findings provide insights into a molecularly distinct subset of BLA neurons that regulates environmental cue-reward associations and drives alcohol seeking behaviors in a projection-specific manner. DisclosuresKJR has received consulting income from Acer, Bionomics, and Jazz Pharma; serves on Scientific Advisory Boards for Sage, Boehringer Ingelheim, Senseye, the Brain and Behavior Research Foundation, and the Brain Research Foundation, and he has received sponsored research support from Alto Neuroscience. None of this work is directly related to the work presented here.

neuroscience↗

bioRxiv2023

Rescue of FTLD-associated TDP-43 pathology and neurodegeneration by peripheral AAV-mediated expression of brain-penetrant progranulin

Progranulin (PGRN) haploinsufficiency is a major risk factor for frontotemporal lobar degeneration with TDP-43 pathology (FTLD-GRN). Multiple therapeutic strategies are in clinical development to restore PGRN levels in the CNS, including gene therapy. However, a limitation of current gene therapy approaches aimed to alleviate FTLD-associated pathologies may be their inefficient brain exposure and biodistribution. We therefore developed an adeno-associated virus (AAV) targeting the liver (L) to achieve sustained peripheral expression of a transferrin receptor (TfR) binding, brain-penetrant (b) PGRN variant (AAV(L):bPGRN) in two mouse models of FTLD-GRN, namely Grn knockout and GrnxTmem106b double knockout mice. This therapeutic strategy avoids potential safety and biodistribution issues of CNS-administered AAVs while maintaining sustained levels of PGRN in the brain following a single dose. AAV(L):bPGRN treatment reduced several FTLD-GRN associated disease pathologies including severe motor function deficits, aberrant TDP-43 solubility and phosphorylation, dysfunctional protein degradation, lipid metabolism, gliosis and neurodegeneration in the brain. Translatability of our findings was confirmed in a novel human in vitro model using co-cultured human induced pluripotent stem cell (hiPSC)-derived microglia lacking PGRN and TMEM106B and wild-type hiPSC-derived neurons. As in mice, aberrant TDP-43, lysosomal dysfunction and neuronal loss were ameliorated after treatment with exogenous TfR-binding protein transport vehicle fused to PGRN (PTV:PGRN). Together, our studies suggest that peripherally administered brain-penetrant PGRN replacement strategies can ameliorate FTLD-GRN relevant phenotypes including TDP-43 pathology, neurodegeneration and behavioral deficits. Our data provide preclinical proof of concept for the use of this AAV platform for treatment of FTLD-GRN and potentially other CNS disorders. One sentence summaryPeripheral AAV-mediated delivery of brain-penetrant PGRN rescues TDP-43 pathology, neurodegeneration and motor phenotypes in FTLD-GRN models.

neuroscience↗

bioRxiv2023

PACAP-mediated gating of anxiety-controlling circuits

Combining the use of ex vivo and in vivo optogenetics, viral tracing, electrophysiology and behavioral testing, we show that the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) gates anxiety-controlling circuits by differentially affecting synaptic efficacy at projections from the basolateral amygdala (BLA) to two different subdivisions of the dorsal subdivision of the bed nucleus of the stria terminalis (BNST), modifying the signal flow in BLA-ovBNST-adBNST circuits in such a way that adBNST is inhibited. Inhibition of adBNST is translated into the reduced firing probability of adBNST neurons during afferent activation, explaining the anxiety-triggering actions of PACAP in BNST, as inhibition of adBNST is anxiogenic. Our results reveal how innate, fear-related behavioral mechanisms may be controlled by neuropeptides, PACAP specifically, at the level of underlying neural circuits by inducing long-lasting plastic changes in functional interactions between their different structural components.

neuroscience↗

bioRxiv2022

Internal needs drive the cephalic phase response in Drosophila melanogaster

Hungry animals consistently show a desire to obtain food. Even a brief sensory detection of food can trigger bursts of physiological and behavioral changes. However, the underlying mechanisms by which the sensation of food triggers the acute behavioral response remain elusive. We have previously shown in Drosophila that hunger drives a preference for low temperature. Because Drosophila is a small ectotherm, a preference for low temperature implies a low body temperature and a low metabolic rate. Here, we show that taste sensing triggers a switch from a low to a high temperature preference in hungry flies. We show that taste stimulation by artificial sweeteners or optogenetics triggers an acute warm preference, but is not sufficient to reach the fed state. Instead, nutrient intake is required to reach the fed state. The data suggest that starvation recovery is controlled by two components: taste-evoked and nutrient-induced warm preferences, and that taste and nutrient quality play distinct roles in starvation recovery. Animals are motivated to eat based on time of day or hunger. We found that clock genes and hunger signals profoundly control the taste-evoked warm preferences. Thus, our data suggest that the taste-evoked response is one of the critical layers of regulatory mechanisms representing internal energy homeostasis and metabolism.

neuroscience↗

bioRxiv2021

Genome-wide transcriptional profiling uncovers a similar oligodendrocyte-related transcriptional response to acute and chronic alcohol drinking in the amygdala

Alcohol intake progressively increases after prolonged consumption of alcohol, but relatively few new therapeutics targeting development of alcohol use disorder (AUD) have been validated. Here, we conducted a genome-wide RNA-sequencing (RNA-seq) analysis in mice exposed to different modes (acute vs chronic) of ethanol drinking. We focused on transcriptional profiles in the amygdala including the central and basolateral subnuclei, a brain area previously implicated in alcohol drinking and seeking, demonstrating distinct gene expression patterns and canonical pathways induced by both acute and chronic intake. Surprisingly, both drinking modes triggered similar transcriptional changes, including up-regulation of ribosome-related/translational pathways and myelination pathways, and down-regulation of chromatin binding and histone modification. Notably, multiple genes that were significantly regulated in mouse amygdala with alcohol drinking, including Atp2b1, Slc4a7, Nfkb1, Nts, and Hdac2, among others had previously been associated with human AUD via GWAS or other genomic studies. In addition, analyses of hub genes and upstream regulatory pathways predicted that voluntary ethanol consumption affects epigenetic changes via histone deacetylation pathways, oligodendrocyte and myelin function, and oligodendrocyte-related transcriptional factor, Sox17. Overall, our results suggest that the transcriptional landscape in the central and basolateral subnuclei of the amygdala is sensitive to voluntary alcohol drinking. They provide a unique resource of gene expression data for future translational studies examining transcriptional mechanisms underlying the development of AUD due to alcohol consumption.

neuroscience↗

bioRxiv2021

Loss of TREM2 reduces hyperactivation of progranulin deficient microglia but not lysosomal pathology

GRN haploinsufficiency causes frontotemporal lobar degeneration and results in microglial hyperactivation, lysosomal dysfunction and TDP-43 deposition. To understand the contribution of microglial hyperactivation to pathology we evaluated genetic and pharmacological approaches suppressing TREM2 dependent transition of microglia from a homeostatic to a disease associated state. Trem2 deficiency in Grn KO mice led to a reduction of microglia activation. To explore antibody-mediated pharmacological modulation of TREM2-dependent microglial states, we identified antagonistic TREM2 antibodies. Treatment of macrophages from GRN-FTLD patients with these antibodies allowed a complete rescue of elevated levels of TREM2 together with increased shedding and reduction of TREM2 signaling. Furthermore, antibody-treated PGRN deficient hiMGL showed dampened microglial hyperactivation, reduced TREM2 signaling and phagocytic activity, however, lack of rescue of lysosomal dysfunction. Similarly, lysosomal dysfunction, lipid dysregulation and glucose hypometabolism of Grn KO mice were not rescued by TREM2 ablation. Furthermore, NfL, a biomarker for neurodegeneration, was elevated in the Grn/Trem2 KO. These findings suggest that microglia hyperactivation is not necessarily contributing to neurotoxicity, and instead demonstrates that TREM2 exhibits neuroprotective potential in this model.

neuroscience↗