Biology subjects

Park, S.

Publications and source records attributed to Park, S..

At least 145 records · Page 8Linked to original sources

bioRxiv2024

Wakefulness induced by TAAR1 partial agonism is mediated through dopaminergic neurotransmission

Trace amine-associated receptor 1 (TAAR1) is known to negatively regulate dopamine (DA) release. The partial TAAR1 agonist RO5263397 promotes wakefulness and suppresses NREM and REM sleep in mice, rats, and non-human primates. We tested the hypothesis that the TAAR1-mediated effects on sleep/wake were due, at least in part, to DA release. Male C57BL6/J mice (n=8) were intraperitoneally administered the D1R antagonist SCH23390, the D2R antagonist eticlopride, a combination of D1R+D2R antagonists or saline at ZT5.5, followed 30 min later by RO5263397 or vehicle (10% DMSO in DI water) at ZT6 per os. EEG, EMG, subcutaneous temperature, and activity were recorded in each mouse across the 8 treatment conditions and sleep architecture was analyzed for 6 hours post-dosing. Consistent with our previous reports, RO5263397 increased wakefulness as well as the latency to NREM and REM sleep. D1, D2, and D1+D2 pretreatment reduced RO5263397-induced wakefulness during the first 1-2 hours after dosing, but only the D1+D2 combination attenuated the wake-promoting effect of RO5263397 from ZT6-8, mostly by increasing NREM sleep. Although D1+D2 antagonism blocked the wake-promoting effect of RO5263397, only the D1 antagonist significantly reduced the TAAR1-mediated increase in NREM latency. Neither the D1 nor the D2 antagonist affected TAAR1-mediated suppression of REM sleep. These results suggest that, whereas TAAR1 effects on wakefulness are mediated in part through the D2R, D1R activation plays a role in reversing the TAAR1-mediated increase in NREM sleep latency. By contrast, TAAR1-mediated suppression of REM sleep appears not to involve D1R or D2R mechanisms.

neuroscience↗

bioRxiv2024

Biophysical modeling of membrane curvature generation and curvature sensing by the glycocalyx

Generation of membrane curvature is fundamental to cellular function. Recent studies have established that the glycocalyx, a sugar-rich polymer layer at the cell surface, can generate membrane curvature. While there have been some theoretical efforts to understand the interplay between the glycocalyx and membrane bending, there remain open questions about how the properties of the glycocalyx affect membrane bending. For example, the relationship between membrane curvature and the density of glycosylated proteins on its surface remains unclear. In this work, we use polymer brush theory to develop a detailed biophysical model of the energetic interactions of the glycocalyx with the membrane. Using this model, we identify the conditions under which the glycocalyx can both generate and sense curvature. Our model predicts that the extent of membrane curvature generated depends on the grafting density of the glycocalyx and the length of the polymers constituting the glycocalyx. Furthermore, when coupled with the intrinsic membrane properties such as spontaneous curvature and a line tension along the membrane, the curvature generation properties of the glycocalyx are enhanced. These predictions were tested experimentally by examining the propensity of glycosylated transmembrane proteins to drive the assembly of highly-curved filopodial protrusions at the plasma membrane of adherent mammalian cells. Our model also predicts that the glycocalyx has curvature sensing capabilities, in agreement with the results of our experiments. Thus, our study develops a quantitative framework for mapping the properties of the glycocalyx to the curvature generation capability of the membrane. Significance StatementThe glycocalyx is a dense layer of glycosylated transmembrane proteins and lipids distributed on the extracellular surface of eukaryotic cells. It is known to mediate cell-cell interactions and protect cells from invasion by pathogens. However, recently it has been found to play a role in generating membrane curvature, which is essential to diverse cellular functions spanning from endocytosis to cell division. Experiments have revealed that different membrane shapes: spherical vesicles, pearls, and tubes are regulated by the glycocalyx. However, currently, we lack a quantitative physical explanation of how glycocalyx properties determine membrane geometries. Here we develop a polymer brush theory-based model, which suggests that the interplay between glycocalyx polymers and membrane bending captures the wide variety of membrane shapes from spherical buds to elongated pearl-like shapes found in previously published experiments. We predict that the physical properties of glycocalyx polymers, line tension, and membrane elastic parameters play significant roles in regulating membrane morphologies. We find that the glycocalyx prefers higher local membrane curvature indicating that the glycocalyx can sense local curvature.

biophysics↗

bioRxiv2024

Inhibiting EZH2 complements steroid effects in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a devastating X-linked disorder caused by mutations in the dystrophin gene. Despite recent advances in understanding the disease etiology and applying emerging treatment methodologies, glucocorticoid derivatives remain the only general therapeutic option that can slow disease development. However, the precise molecular mechanism of glucocorticoid action remains unclear, and there is still need for additional remedies to complement the treatment. Here, using single-nucleus RNA-sequencing and spatial transcriptome analyses of human and mouse muscles, we investigated pathogenic features in DMD patients and palliative effects of glucocorticoids. Our approach further illuminated the importance of proliferating satellite cells, and revealed increased activity of a signal transduction pathway involving EZH2 in the patient cells. Subsequent administration of EZH2 inhibitors to Dmd mutant mice resulted in improved muscle phenotype through maintaining the immune-suppressing effect but overriding the muscle weakness and fibrogenic effects exerted by glucocorticoids. Our analysis reveals pathogenic mechanisms that can be readily targeted by extant therapeutic options for DMD. TeaserA survey of DMD tissues in human and mouse suggests EZH2 as a critical factor in DMD satellite cells; its inhibition resulted in better prognosis.

genetics↗

bioRxiv2024

HSP90 interacts with VP37 to facilitate the cell-to-cell movement of broad bean wilt virus 2

The systemic spread of viruses in plants requires successful viral cell-to-cell movement through plasmodesmata (PD). Viral movement proteins (MPs) interact with cellular proteins to modify and utilize host transport routes. Broad bean wilt virus 2 (BBWV2), a widespread plant RNA virus, moves from cell to cell as a virion through the PD gated by VP37, the MP of BBWV2. However, the host proteins that function in the cell-to-cell movement of BBWV2 remain unclear. In this study, we identified cellular heat shock protein 90 (HSP90) as an interacting partner of VP37. The interaction between HSP90 and VP37 was assessed using the yeast two-hybrid assay, co-immunoprecipitation, and bimolecular fluorescence complementation. Tobacco rattle virus-based virus-induced gene silencing analysis revealed that HSP90 silencing significantly inhibited the systemic spread of BBWV2 in N. benthamiana plants. Furthermore, in planta treatment with geldanamycin (GDA), an inhibitor of the chaperone function of HSP90, demonstrated the necessity of HSP90 in successful cell-to-cell movement and systemic infection of BBWV2. Interestingly, GDA treatment inhibited the HSP90-VP37 interaction at the PD, resulting in the inhibition of VP37-derived tubule formation through the PD. Our results suggest that the HSP90-VP37 interaction regulates VP37-derived tubule formation through the PD, thereby facilitating the cell-to-cell movement of BBWV2. IMPORTANCEThis study highlights the regulatory role of heat shock protein 90 (HSP90) in facilitating the cell-to-cell movement of broad bean wilt virus 2 (BBWV2). HSP90 interacted with VP37, the movement protein of BBWV2, specifically at plasmodesmata (PD). This study demonstrated that the HSP90-VP37 interaction is crucial for viral cell-to-cell movement and the formation of VP37-derived tubules, which are essential structures for virus transport through the PD. The ATP-dependent chaperone activity of HSP90 is integral to this interaction, as demonstrated by the inhibition of virus movement upon treatment with geldanamycin (GDA), which disrupts the function of HSP90. These findings elucidate the molecular mechanisms underlying the cell-to-cell movement of plant viruses, and highlight the role of HSP90 in viral infection. This study suggests that the chaperone activity of HSP90 may function in changing the conformational structure of VP37, thereby facilitating the assembly and function of virus-induced structures required for viral cell-to-cell movement.

microbiology↗

bioRxiv2024

Ophthalmic acid is a bloodborne metabolite that contributes to age-induced cardiomyocyte hypertrophy

Cardiac aging involves the development of left ventricular hypertrophy alongside a decline in functional capacity. Here, we use neutral blood exchange to demonstrate that the acute removal of age-accumulated blood factors significantly regresses cardiac hypertrophy in aged mice. The reversal of hypertrophy was not attributed to age-associated hemodynamic effects, implicating a role of blood-derived factors. In addition, the overarching paradigm of systemic aging maintains that the age-related overabundance of plasma proteins are largely responsible for causing pathological phenotypes in tissues. Our results suggest that blood metabolites, not proteins, drive cardiac hypertrophy instead. Upon analyzing serum metabolomics data sets, we identified ophthalmic acid as a circulating metabolite whose levels increase with advanced age. Treatment of adult mouse and neonatal rat cardiomyocytes in culture with ophthalmic acid increased their relative surface areas. This study uncovers a non-protein metabolite that may contribute to cardiomyocyte hypertrophy during aging. Identifying a method to counteract ophthalmic acids hypertrophic effects may reveal novel therapeutic opportunities for cardiac rejuvenation.

physiology↗

bioRxiv2024

Direct imaging of neural activity reveals neural circuits via spatiotemporal activation mapping

Two years ago, our group reported direct imaging of neuronal activity (DIANA), a functional magnetic resonance imaging (fMRI) technique that directly detects neuronal activity at high spatiotemporal resolution. In this study, we successfully reproduced the DIANA response in medetomidine-anesthetized mice using forelimb electrical stimulation at 11.7 T. More importantly, we showed that multiple neural circuits can be effectively revealed by DIANA fMRI through spatiotemporal activation mapping. The spatiotemporal activation mapping proposed here utilizes the temporal information of the DIANA response, that is, the time when the DIANA response reaches its peak, which is a unique feature that distinguishes it from the activation mapping method used in existing fMRI. Based on DIANA activation areas, we identified several neural circuits involved in forelimb sensory processing in the somatosensory network, which includes multiple brain regions: ventral posterolateral nucleus of the thalamus (VPL), posteromedial thalamic nucleus (POm), forelimb primary somatosensory cortex (S1FL), secondary somatosensory cortex (S2), primary motor cortex (M1), and secondary motor cortex (M2). Additionally, we also identified a pain-related neural circuit involving brain regions of the anterior cingulate cortex (ACC) and mediodorsal nucleus (MD). Interestingly, the spatiotemporal activation mapping also allowed us to identify subregions with different DIANA response times within the same functional region (e.g., VPL, POm, S1FL, and S2). Our study highlights the potential of DIANA fMRI to advance our understanding of sensory information processing throughout the brain and to provide insight into the spatiotemporal dynamics of brain networks at the level of neural circuits.

neuroscience↗

bioRxiv2024

Gustatory Thalamic Neurons Mediate Aversive Behaviors

The parvicellular part of the ventral posteromedial nucleus (VPMpc) of the thalamus, also known as the gustatory thalamus, receives input from the parabrachial nucleus and relays taste sensation to the gustatory (or insular) cortex. Prior research has focussed on the role of the VPMpc in relaying taste signals. Here we provide evidence showing that VPMpc also mediates aversive behaviors. By recording calcium transients in vivo from single neurons in mice, we show that neurons expressing cholecystokinin and the mu-opioid receptor in the VPMpc respond to various noxious stimuli and fear memory. Chemogenetic and optogenetic activation of these neurons enhances the response to aversive stimuli, whereas silencing them attenuates aversive behaviors. The VPMpc neurons directly innervate neurons in the insular cortex and rostral lateral amygdala. This study expands the role of the VPMpc to include mediating aversive and threating signals to the insular cortex and lateral amygdala.

neuroscience↗

bioRxiv2024

Genetic basis of state-dependent courtship sounds in inbred mice

Courtship behaviors consist of two phases, namely the appetitive and consummatory states. Despite the long history of the concept, few studies have been done regarding the genetic contribution on those two different phases. Male mice are known to produce distinct ultrasonic vocalizations (USVs) as they progress through courtship states1-14, and these courtship sounds also show strain-specific differences15-18. Here, we delved into USV syllable patterns emitted during specific courtship actions using inbred mouse strains and their progeny: C57BL/6J (B6) mice, 129S4/SvJae (129) mice, and their second filial generation (F2) offspring of mixed genetic backgrounds. B6, 129, and F2 mice generated similar USV syllables during mounting behavior. In contrast, B6 and 129 mice showed different USV syllable patterns during body and anogenital sniffing behavior, and the USV syllable usage of F2 mice in this courtship state diverged according to the degree of genetic similarity with B6 or 129 mice. From these results, we propose that differential selection pressures19-20 favored diversity in appetitive behavior but conservation in consummatory behaviors.

animal behavior and cognition↗

bioRxiv2024

A scene with an invisible wall - navigational experience shapes visual scene representation

Human navigation heavily relies on visual information. Although many previous studies have investigated how navigational information is inferred from visual features of scenes, little is understood about the impact of navigational experience on visual scene representation. In this study, we examined how navigational experience influences both the behavioral and neural responses to a visual scene. During training, participants navigated in the virtual reality (VR) environments which we manipulated navigational experience while holding the visual properties of scenes constant. Half of the environments allowed free navigation (navigable), while the other half featured an invisible wall preventing the participants to continue forward even though the scene was visually navigable (non-navigable). During testing, participants viewed scene images from the VR environment while completing either a behavioral perceptual identification task (Experiment1) or an fMRI scan (Experiment2). Behaviorally, we found that participants judged a scene pair to be significantly more visually different if their prior navigational experience varied, even after accounting for visual similarities between the scene pairs. Neurally, multi-voxel pattern of the parahippocampal place area (PPA) distinguished visual scenes based on prior navigational experience alone. These results suggest that the human visual scene cortex represents information about navigability obtained through prior experience, beyond those computable from the visual properties of the scene. Taken together, these results suggest that scene representation is modulated by prior navigational experience to help us construct a functionally meaningful visual environment.

neuroscience↗

bioRxiv2024

A stabilized MERS-CoV spike ferritin nanoparticle vaccine elicits robust and protective neutralizing antibody responses

Middle East respiratory syndrome coronavirus (MERS-CoV) was first identified as a human pathogen in 2012 and causes ongoing sporadic infections and outbreak clusters. Despite case fatality rates (CFRs) of over 30% and the pandemic potential associated with betacoronaviruses, a safe and efficacious vaccine has not been developed for prevention of MERS in at-risk individuals. Here we report the design, in vitro characterization, and preclinical evaluation of MERS-CoV antigens. Our lead candidate comprises a stabilized spike ectodomain displayed on a self-assembling ferritin nanoparticle that can be produced from a high-expressing, stable cell pool. This vaccine elicits robust antibody titers in BALB/c mice as measured by MERS- CoV pseudovirus and live-virus neutralization assays. Immunization of non-human primates (NHPs) with a single dose of Alhydrogel-adjuvanted vaccine elicits >103 geometric mean titer (GMT) of pseudovirus neutralizing antibodies that can be boosted with a second dose. These antibody levels are durable, with GMTs that surpass the post-prime levels for more than 5 months post-boost. Importantly, sera from these NHPs exhibit broad cross-reactivity against lentiviruses pseudotyped with spike proteins from MERS-CoV clades A, B, and C as well as a more distant pangolin merbecovirus. In transgenic mice expressing human DPP4, immunization provided dose-dependent protection against MERS-CoV lethal challenge, and in an established alpaca challenge model, immunization fully protected against MERS-CoV infection. This protein-based MERS-CoV nanoparticle vaccine is a promising candidate for advancement to clinical development to protect at-risk individuals and for future use in a potential outbreak setting.

biochemistry↗

bioRxiv2024

The effect of circulating neutralizing antibodies on the replication of SARS-CoV-2 variants following post-vaccination infections.

The impact of pre-existing neutralizing antibodies (NAbs) titers on SARS-CoV-2 viral shedding dynamics in post-vaccination infection (PVI) are not well understood. We characterized viral shedding longitudinally in nasal specimens in relation to baseline (pre/peri-infection) serum neutralizing antibody titers in 125 participants infected with distinct SARS-CoV-2 variants. Among 68 participants who had received vaccinations, we quantified the effect of baseline serum NAb titers on maximum viral RNA titers and on the duration of infectivity. Baseline NAb titers were higher and efficiently targeted a broader range of variants in participants who received one or two monovalent ancestral booster vaccinations compared to those with a full primary vaccine series. In participants with Delta variant infections, baseline NAb titers targeting Delta were negatively correlated with maximum viral RNA copies. Per log10 increase in baseline NAb IC50, maximum viral load was reduced -2.43 (95% confidence interval [CI] -3.76, -1.11) log10 N copies and days of infectious viral shedding were reduced -2.79 [95% CI: -4.99, -0.60] days. By contrast, in those with Omicron infections (BA.1, BA.2, BA.4 or BA.5 lineages) baseline NAb responses against Omicron lineages did not predict viral outcomes. Our results provide robust estimates of the effect of baseline NAbs on the magnitude and duration of nasal viral replication after PVI (albeit with an unclear effect on transmission) and show how immune escape variants efficiently evade these modulating effects.

immunology↗

bioRxiv2024

Experimental evolution of Escherichia coli on solid silver, copper, stainless steel, and glass surfaces

To study bacterial adaptation to antimicrobial metal surfaces in application-relevant conditions, Escherichia coli was exposed to copper and silver surfaces for thirty exposure cycles in low-organic dry or high-organic humid conditions. The evolved populations demonstrated increased metal surface tolerance without concurrent increase in MBC and MIC values of respective metal ions or selected antibiotics. Mutation analysis did not detect increased mutation accumulation nor mutations in cop, cus, cue, sil, pco or general efflux genes known to actively maintain copper/silver homeostasis. Instead, during cyclic exposure mutations in genes related to cellular barrier functions and sulfur metabolism were enriched potentially suggesting that reducing bioavailability and passively restricting uptake of the toxic metals rather than active efflux is selected for on copper and silver surfaces. The changes detected in the evolved populations did not indicate an increased risk of antibiotic cross-resistance as a result of copper or silver surface exposure. However, rapid emergence of mutations in silS activated the cryptic sil efflux locus during silver ion challenge in liquid MBC assay with the evolved populations. The silS mutants showed no benefit on copper and silver surfaces but demonstrated decreased sensitivity to ampicillin and ciprofloxacin as well as copper and silver ions in liquid tests indicating that efflux might be specific to granting heavy metal tolerance in liquid but not surface exposure format. Our findings highlight the critical importance of appropriate exposure conditions not only in efficacy assessment but also risk assessment of antimicrobial surface applications. ImportanceThis study examines the evolutionary adaptations of Escherichia coli after semi-dry exposure to copper and silver surfaces, leading to an increase in surface tolerance but no increase in mutation accumulation or substantially enhanced metal ion tolerance in standard tests. Notably, enriched mutations indicate a shift toward more energy-passive mechanisms of metal tolerance. Additionally, while enhanced silver efflux was rapidly selected for in a single round of silver exposure in liquid tests and substantially increased copper and silver ion tolerance in conventional test formats, the causal mutations did not improve viability on silver and copper surfaces, underscoring the different fitness scenarios of tolerance mechanisms dependent on exposure conditions. These findings emphasize the need for appropriate exposure conditions in evaluating of both efficacy and the potential risks of using antimicrobial surfaces, as the results from conventional liquid-based tests may not apply in solid contexts.

microbiology↗

bioRxiv2024

Dual-mode action of scalable, high-quality engineered stem cell-derived SIRP alpha extracellular vesicles for treating acute liver failure

Acute liver failure (ALF) is a critical inflammatory condition characterized by rapid hepatocyte death, impaired liver regeneration due to the delayed removal of necroptotic cells, and high mortality rates. This study introduces a novel dual-mode action therapeutic approach using extracellular vesicles expressing Signal Regulatory Protein Alpha (SIRP-EVs) derived from genetically engineered mesenchymal stem cells (MSCs). These SIRP-EVs are designed to concurrently resolve necroptosis and promote liver regeneration. Our studies identified CD47 and SIRP as promising therapeutic targets for ALF. We developed a scalable 3D bioreactor-based process that produces high-purity SIRP-EVs, which preserve MSC properties and achieve significant production levels. SIRP-EVs target both macrophages and necroptotic hepatocytes in ALF models, enhancing macrophage phagocytic activity against necroptotic cells via CD47 blockade and promoting liver regeneration by reprogramming macrophages with MSC-derived cargo. Comprehensive in vitro and in vivo studies demonstrate that SIRP-EVs decrease CD47+ necroptotic cells and promote liver regeneration in ALF models, leading to reduced liver damage markers and enhanced survival rates. These findings highlight the potential of SIRP-EVs as a dual-mode action therapeutic for ALF, offering promising prospects for their application in other inflammatory diseases. Moreover, these results pave the way for advancing engineered EV-based therapies toward clinical implementation.

bioengineering↗

bioRxiv2024

A novel splicing graph allows a direct comparison between exon-based and splice junction-based approaches to alternative splicing detection

There are primarily two computational approaches to alternative splicing detection: splice junction-based and exon-based approaches. Despite their shared goal of addressing the same biological problem, these approaches have not been reconciled before. We devised a novel graph structure and algorithm aimed at mapping between the exonic parts and splicing events detected by the two different methods. Through simulations, we demonstrated disparities in sensitivity and specificity between splice junction-based and exon-based methods. When applied to empirical data, there were large discrepancies in the results, suggesting that the methods are complementary. With the discrepancies localized to individual events and exonic parts, we were able to gain insights into the strengths and weaknesses inherent in each approach. Finally, we integrated the results to generate a comprehensive list of both common and unique alternative splicing events detected by both methodologies. Availabilityhttps://github.com/HanLabUNLV/GrASE Contactmira.han@unlv.edu Supplementary informationSupplementary data are available online.

bioinformatics↗

bioRxiv2024

Dimerization activates the Inversin complex in C. elegans

Genetic, colocalization, and biochemical studies suggest that the ankyrin repeat-containing proteins Inversin (INVS) and ANKS6 function with the NEK8 kinase to control tissue patterning and maintain organ physiology. It is unknown whether these three proteins assemble into a static "Inversin complex" or one that adopts multiple bioactive forms. Through characterization of hyperactive alleles in C. elegans, we discovered that the Inversin complex is activated by dimerization. Genome engineering of an RFP tag onto the nematode homologs of INVS (MLT-4) and NEK8 (NEKL-2) induced a gain-of-function, cyst-like phenotype that was suppressed by monomerization of the fluorescent tag. Stimulated dimerization of MLT-4 or NEKL-2 using optogenetics was sufficient to recapitulate the phenotype of a constitutively active Inversin complex. Further, dimerization of NEKL-2 bypassed a lethal MLT-4 mutant, demonstrating that the dimeric form is required for function. We propose that dynamic switching between at least two functionally distinct states--an active dimer and an inactive monomer--gates the output of the Inversin complex.

cell biology↗

bioRxiv2024

Efficient DNA base editing via an optimized DYW-like deaminase

CRISPR-based cytosine base editors enable precise genome editing without inducing double-stranded DNA breaks, yet traditionally depend on a limited selection of deaminases from the APOBEC/AID or TadA families. Here, we introduce SsCBE, a novel CRISPR-based cytosine base editor utilizing SsdAtox, a DYW-like deaminase derived from the toxin of Pseudomonas syringae. Strategic engineering of SsdAtox has led to remarkable improvements in the base editing efficiency (by up to 8.4-fold) and specificity for SsCBE, while concurrently reducing cytotoxicity. Exhibiting exceptional versatility, SsCBE was delivered and efficiently applied using diverse delivery methods, including the engineered virus-like particles (eVLPs). Its application has enabled targeted cytosine base editing in mouse zygotes and pioneering edits in mitochondrial DNA. The advent of SsCBE marks a significant advancement in the CRISPR toolkit, providing a versatile tool for advanced research and therapeutic strategies.

molecular biology↗

bioRxiv2024

FAM19A5 Deficiency Mitigates the Aβ Plaque Burden and Improves Cognition in Mouse Models of Alzheimer's Disease

FAM19A5, a novel secretory protein highly expressed in the brain, is potentially associated with the progression of Alzheimers disease (AD). However, its role in the AD brain remains unclear. Here, we investigated the potential function of FAM19A5 in the context of AD. We generated APP/PS1 mice with partial FAM19A5 deficiency, termed APP/PS1/FAM19A5+/LacZ mice. Compared to control APP/PS1 mice, APP/PS1/FAM19A5+/LacZ mice exhibited significantly lower A{beta} plaque density, suggesting that FAM19A5 reduction mitigates A{beta} plaque formation. Notably, partial FAM19A5 depletion also prolonged the lifespan of the APP/PS1 mice. To further explore the therapeutic potential of targeting FAM19A5, we developed an anti-FAM19A5 antibody. Administration of this antibody to APP/PS1 mice significantly improved their performance in the novel object recognition test, demonstrating enhanced cognitive function. This effect was reproduced in 5XFAD mice, a model of early-onset AD characterized by rapid A{beta} accumulation. Additionally, anti-FAM19A5 antibody treatment in 5XFAD mice led to increased spontaneous alternation behavior in the Y-maze test, indicating improved spatial working memory. These findings suggest that anti-FAM19A5 antibodies may be a promising therapeutic strategy for AD by reducing A{beta} plaques and improving cognitive function.

neuroscience↗

bioRxiv2024

Dopey-dependent regulation of extracellular vesicles maintains neuronal morphology

Mature neurons maintain their distinctive morphology for extended periods in adult life. Compared to developmental neurite outgrowth, axon guidance, and target selection, relatively little is known of mechanisms that maintain mature neuron morphology. Loss of function in C. elegans DIP-2, a member of the conserved lipid metabolic regulator Dip2 family, results in progressive overgrowth of neurites in adults. We find that dip-2 mutants display specific genetic interactions with sax-2, the C. elegans ortholog of Drosophila Furry and mammalian FRY. Combined loss of DIP-2 and SAX-2 results in severe disruption of neuronal morphology maintenance accompanied by increased release of neuronal extracellular vesicles (EVs). By screening for suppressors of dip-2 sax-2 double mutant defects we identified gain-of-function (gf) mutations in the conserved Dopey family protein PAD-1 and its associated phospholipid flippase TAT-5/ATP9A. In dip-2 sax-2 double mutants carrying either pad-1(gf) or tat-5(gf) mutation, EV release is reduced and neuronal morphology across multiple neuron types is restored to largely normal. PAD-1(gf) acts cell autonomously in neurons. The domain containing pad-1(gf) is essential for PAD-1 function, and PAD-1(gf) protein displays increased association with the plasma membrane and inhibits EV release. Our findings uncover a novel functional network of DIP-2, SAX-2, PAD-1, and TAT-5 that maintains morphology of neurons and other types of cells, shedding light on the mechanistic basis of neurological disorders involving human orthologs of these genes.

neuroscience↗