Biology subjects

Chung, K.

Publications and source records attributed to Chung, K..

At least 19 recordsLinked to original sources

bioRxiv2026

An integrated multi-omic atlas of the choroid plexus highlights conserved molecular programs of epithelial function

The choroid plexus (ChP) is a specialized epithelial tissue responsible for production of cerebrospinal fluid (CSF), maintenance of the blood-CSF barrier and regulation of CSF-borne signaling factors. However, despite the ChP's central role in CSF homeostasis, conserved molecular programs of ChP epithelial function across species and conditions remain incompletely defined. In this study, we integrated eight mouse and human single-cell/nucleus RNA-seq datasets to build a multi-species ChP atlas capturing major epithelial, stromal, vascular, and immune populations. Cross-dataset differential expression identified a conserved epithelial gene program encompassing ion transport, barrier function, ciliogenesis, and secretory signaling, while prioritizing understudied genes including CLIC6 and VAT1L. Co-expression network analysis resolved conserved epithelial meta-programs, and transcription factor regulatory inference identified OTX2, MSX1, and GLIS3 among conserved regulators of epithelial gene expression. We also generated a novel Visium HD spatial transcriptomic atlas of mouse fourth-ventricle ChP to orthogonally validate epithelial modules. Lastly, cross-tissue analyses revealed substantial transcriptional overlap between ChP and retinal pigment epithelium, including shared epithelial genes and OTX2-associated regulatory relationships. Together, these findings define conserved molecular programs of ChP epithelial specialization, nominate candidate regulators for functional investigation, and provide an integrated cross-species and spatial resource for studying ChP physiology.

neuroscience↗

bioRxiv2026

Combined HDAC and ATM inhibition with radiation in preclinical glioblastoma models

Background: Brain-penetrant histone deacetylase inhibitors (HDACi) are promising radiosensitizing agents for glioblastoma (GBM). HDAC inhibitors can impair DNA damage response (DDR) pathways and promote persistent DNA damage. Here, we evaluated whether combined inhibition of HDAC and the DNA repair kinase, ataxia-telangiectasia mutated (ATM), could synergize with radiation (IR) and improve therapeutic efficacy in GBM. Methods: In vitro dose-response assays were performed in patient-derived xenograft (PDX)-derived glioma stem cells (GSCs) with both inhibitors of HDAC (quisinostat, QST) and ATM (AZD1390) with or without IR treatment to assess synergy. Pharmacodynamic responses were evaluated by immunoblotting for histone acetylation, DDR signaling, and DNA damage markers. Transcriptomic analyses were performed to evaluate treatment-associated changes in DNA repair pathways. The combination of QST, AZD1390, and IR was further evaluated in an orthotopic GBM survival study. Results: Combined treatment with QST and AZD1390 produced synergistic radiosensitization in multiple GSC models in vitro. Furthermore, QST combined with IR suppressed transcription of homologous recombination (HR) pathway genes in GSCs, impairing double-strand break repair capacity through an epigenetic mechanism that does not directly inhibit ATM kinase activity. Pharmacodynamic analyses confirmed that QST increased histone acetylation while AZD1390 suppressed ATM signaling, together impairing complementary mechanisms to increase radiosensitivity of GSCs. In an orthotopic GBM model, QST combined with IR significantly prolonged survival compared with IR alone. However, the addition of AZD1390 did not provide a significant survival benefit beyond QST+IR, and AZD1390 combined with IR did not significantly improve survival relative to IR alone. Conclusions: Combined HDAC and ATM inhibition with QST and AZD1390 enhances radiosensitivity in patient-derived GBM cells, mechanistically underpinned by QST-mediated increase in DNA damage and dual disruption of DDR through complementary, non-overlapping mechanisms. However, this in vitro synergy did not confer additional survival benefit beyond QST+IR in an orthotopic GBM model under the dosing conditions tested, suggesting pharmacological limitations with the tumor microenvironment or suboptimal dosing schedules may have constrained in vivo efficacy.

cancer biology↗

bioRxiv2026

EvoStructCLIP: A Mutation-Centered Multimodal Embedding Model for CAGI7 Variant Effect Prediction

AO_SCPLOWBSTRACTC_SCPLOWWe present EvoStructCLIP, a mutation-centered multimodal embedding model that integrates local 3D structural windows and evolutionary constraints to predict missense variant effects. EvoStructCLIP combines two encoders: a structure voxel encoder derived from AlphaFold residue neighborhoods and an MSA-based evolutionary encoder. It aligns the modalities through CLIP-style contrastive learning, with FuseMix regularization and an auxiliary pathogenicity loss trained on 153,787 ClinVar variants. Evaluations using lightweight regressors demonstrate that EvoStructCLIP embeddings capture highly transferable predictive signals across diverse phenotypes, including gene-specific functional readouts of BRCA1, KCNQ4, and PTEN/TPMT. This transferability is further supported in the CAGI7 blind competition setting, where models generalized to predicting different gene-specific readouts for BARD1, FGFR, and TSC2 without target-specific retraining and achieved competitive performance across heterogeneous biological tasks.

bioinformatics↗

bioRxiv2026

Efficient multi-lineage cardiovascular differentiation of human pluripotent stem cells in animal serum-free conditions

Human induced pluripotent stem cell (hiPSC) technologies offer human-relevant cardiac models for biomedical applications. However, workflows for differentiation of cardiac stromal cells and fabrication of engineered heart tissue (EHT) commonly rely on animal serum, contrary to growing policy demands to reduce use of these products. Applying marker analysis via COL1A, DDR2 and GATA4 for cardiac fibroblasts or CD31, CD34 and CD144 for endothelial cells, we tailored Panexin, a defined serum substitute, to support high efficiency differentiation of cardiac stromal lineages to 85% purity without additional purification steps. We evaluated fabrication of EHTs using hiPSC-cardiomyocytes only (monoculture) or further combined with cardiac fibroblasts and endothelial cells (triculture; 70%:15%:15%, respectively). Panexin poorly supported fabrication and contractility of EHTs, a finding unaltered by modulating spontaneous cardiac myofibroblast activation via TGF{beta} inhibition. In contrast, human serum enabled fabrication of mono- and tri-culture EHTs, wherein constructs made without TGF{beta} signalling inhibition delivered the strongest contractile forces (up to 0.25 mN) and exceeded comparator tissues engineered using animal serum. Our data show that iterative evaluation of serum substitutes, human serum, cell combinations and signalling pathway modulators can mitigate use of animal serum for functional EHT generation, aligning with the UK governments roadmap for alternative methods.

cell biology↗

bioRxiv2026

Establishing the molecular basis for MDA5 mutation-linked autoimmunity

Melanoma differentiation-associated protein 5 (MDA5), a member of the RIG-I-like receptor family, is a cytoplasmic sensor essential for innate antiviral immunity. MDA5 distinguishes viral RNA from host RNA in part through its ATP hydrolysis activity, which promotes filament turnover on shorter endogenous dsRNAs. Here, we show that the gain-of-function T331I disease-linked mutation within the ATP binding pocket disrupts this balance, resulting in constitutive interferon signaling. Through a combination of cryo-electron microscopy (cryoEM), biochemical assays, and cellular analyses, we reveal the extensive network of interactions that precisely position ATP for catalysis in the wild-type MDA5 ATP binding pocket, and also demonstrate that the T331I mutation impairs ATPase activity, thereby stabilizing MDA5-dsRNA complexes and leading to aberrant immune activation. These findings elucidate how MDA5 ATPase activity regulates antiviral specificity and prevents autoimmunity by controlling filament stability and downstream signaling, offering a mechanistic molecular explanation for disease pathogenesis.

biochemistry↗

bioRxiv2025

A Precisely Controlled Long-Acting Immunosuppression Platform Enables Prolonged Survival of Vascularized Composite Allografts

Vascularized composite allotransplantation (VCA) restores complex tissue defects but demands lifelong systemic immunosuppression. Oral tacrolimus (TAC) is limited by a narrow therapeutic window, pharmacokinetic variability, adherence challenges, and toxicity. Local delivery could mitigate these issues, yet clinical translation has been hindered by burst release, short duration, and the inability to co-deliver agents. We developed PRECISE (Programmable, REtrievable, Controlled ImmunoSuppression Encapsulator), an injectable, in-situ-forming PLGA depot that achieves long-acting, tightly controlled TAC release via structure-guided co-formulation with drug-binding agents (DBAs). GRAS small molecules (e.g., EGCG, maltotriose) identified by in silico docking and in vitro screening suppressed burst and modulated solvent efflux. Notably, rapamycin (RAPA) served dually as an mTOR inhibitor and a TAC-binding excipient, enabling synchronized dual-agent delivery. PRECISE eliminated burst in vitro and produced coordinated TAC+RAPA release with clinically compatible injectability. In rats, monthly intragraft dosing maintained systemic TAC/RAPA within the therapeutic window ([~]5-10 ng/mL) for >300 days, prolonged hindlimb allograft survival, expanded Tregs, and induced donor-specific hyporesponsiveness. Surgical retrieval of the depot triggered rapid TAC decline, demonstrating reversibility. In a stringent, fully MHC-mismatched porcine VCA model, PRECISE maintained on-target drug levels and extended graft survival beyond 90 days with minimal rejection and preserved vascular integrity. PRECISE is, to our knowledge, the first retrievable, injectable platform to deliver long-acting, dual-agent immunosuppression with controlled kinetics, rapid attainment of therapeutic steady state, and sustained graft protection. Its modular, structure-guided design enables clinical translation across VCA and solid-organ transplantation, delivering precise, durable, and safer immunosuppression.

bioengineering↗

bioRxiv2025

MCL1 may not mediate chemoresistance

The anti-apoptotic BCL2 family member MCL1 is overexpressed in many cancers and has been linked to chemoresistance. Unlike other BCL2 family members, MCL1 displays both well-defined mitochondrial anti-apoptotic activities and also emerging nuclear functions. Prior reports suggest that MCL1 enters the nucleus during chemotherapy and promotes chemoresistance by influencing cell cycle progression and DNA repair. These nuclear roles of MCL1, however, remain poorly characterized. Using a newly validated monoclonal antibody across several cell lines and treatments, we find no evidence that MCL1 enhances chemoresistance or preferentially accumulates in the nucleus after drug exposure. Proximity biotinylation identified novel nuclear MCL1 interactors but did not recover previously reported DNA repair or cell cycle partners. Thus, while MCL1 does reach the nucleus and interact with nuclear proteins, our data do not support a role for MCL1 in chemoresistance. Further work is needed to clarify the functional significance of nuclear MCL1. SIGNFIGANCEPrevious studies have implicated MCL1 in promoting chemoresistance via interactions with DNA repair machinery in the nucleus. Using a validated, monoclonal anti-MCL1 antibody, we were unable to replicate these data. We report that MCL1 neither confers chemoresistance, translocates to the nucleus during chemotherapy treatment, nor interacts with DNA repair proteins in live cancer cells.

cell biology↗

bioRxiv2024

The noncoding circular RNA circHomer1 regulates developmental experience-dependent plasticity in mouse visual cortex

Circular RNAs (circRNAs) are a class of closed-loop, single stranded RNAs whose expression is particularly enriched in the brain. Despite this enrichment and evidence that the expression of circRNAs are altered by synaptic development and in response to synaptic plasticity in vitro, the regulation by and function of the majority of circRNAs in experience-dependent plasticity in vivo remain unexplored. Here, we employed transcriptome-wide analysis comparing differential expression of both mRNAs and circRNAs in juvenile mouse primary visual cortex (V1) following monocular deprivation (MD), a model of experience-dependent developmental plasticity. Among the differentially expressed mRNAs and circRNAs following 3-day MD, the circular and the activity-dependent mRNA forms of the Homer1 gene, circHomer1 and Homer1a respectively, were of interest as their expression changed in opposite directions: circHomer1 expression increased while the expression of Homer1a decreased following 3-day MD. Knockdown of circHomer1 delayed the depression of closed-eye responses normally observed after 3-day MD. circHomer1-knockdown also led to a reduction in average dendritic spine size prior to MD but critically there was no further reduction after 3-day MD, consistent with impaired structural plasticity. circHomer1-knockdown also prevented the reduction of surface AMPA receptors after 3-day MD. Synapse-localized puncta of the AMPA receptor endocytic protein Arc increased in volume after MD but were smaller in circHomer1-knockdown neurons, suggesting that circHomer1 knockdown impairs experience-dependent AMPA receptor endocytosis. Thus, the expression of multiple circRNAs are regulated by experience-dependent developmental plasticity, and our findings highlight the essential role of circHomer1 in V1 synaptic development and experience-dependent plasticity. Significance StatementCircular RNAs (circRNAs) are a class of closed-loop RNAs formed through back-splicing of exon and/or intron junctions. Initially considered as byproducts of aberrant RNA splicing with limited function, recent studies have implicated circRNAs in various neurological disorders. Despite their abundant expression in the brain, the role of circRNAs in experience-dependent plasticity remains poorly understood. We conducted an in vivo transcriptome analysis of circRNAs whose expression was regulated by experience-dependent plasticity in the mouse visual cortex and highlight circHomer1, a circRNA derived from the Homer1 gene, as a circRNA critical for synaptic development and experience-dependent plasticity in vivo.

neuroscience↗

bioRxiv2024

Utility of Cellular Measurements of Non-Specific Endocytosis to Assess the Target-Independent Clearance of Monoclonal Antibodies

Past studies have demonstrated higher clearance for monoclonal antibodies possessing increased rates of non-specific endocytosis. However, this metric is oftentimes evaluated indirectly using biophysical techniques or cell surface binding studies that may not provide insight into the specific rates of cellular turnover. Furthermore, few examples evaluating non-specific endocytosis have been reported for a therapeutic antibody that reached clinical assessment. In the current report, we evaluated a therapeutic human immunoglobulin G2 monoclonal antibody targeted against the interleukin-4 receptor alpha chain (IL-4R) that exhibited elevated target independent clearance in previous Phase 1 and 2 studies. We confirmed high non-specific clearance of the anti-IL-4R antibody as compared to a reference antibody during pharmacokinetic assessments in wild type mice where target-mediated disposition was absent. We then developed a cell-based method capable of measuring cellular protein endocytosis and demonstrated the anti-IL-4R antibody exhibited marked non-specific uptake relative to the reference compound. Antibody homology modeling identified the anti-IL-4R antibody possessed positive charge patches whose removal via targeted mutations substantially reduced its non-specific endocytosis. We then expanded the scope of the study by evaluating a panel of consisting of both preclinical and clinical monoclonal antibodies and demonstrate those with the highest rates of non-specific uptake in vitro exhibit elevated target independent clearance, low subcutaneous bioavailability, or both. Our results support the observation that high non-specific endocytosis is a negative attribute in monoclonal antibody development and demonstrate the utility of a generic cell-based screen as a quantitative tool to measure non-specific endocytosis of protein therapeutics at the single-cell level. Highlights- Developed a novel, reproducible cellular assay to directly quantify non-specific endocytosis of therapeutic proteins. - A previous clinical candidate monoclonal antibody with rapid target-independent clearance in mice and humans possessed extensive non-specific endocytosis that was due to exposed positive charge features. - Demonstration of distinct rates of endocytosis into mammalian cells for disparate monoclonal antibodies, even those with common specificity for targets or isoelectric points. - Cell-based assay to quantify the potential impact of non-specific endocytosis on target-independent clearance and/or subcutaneous bioavailability of monoclonal antibodies.

biochemistry↗

bioRxiv2024

Performance of GPT-4 on the American College of Radiology In-Service Examination

ObjectivesNo study has evaluated the ability of ChatGPT-4 to answer image-rich diagnostic radiology board exam questions or assessed for model drift in GPT-4s image interpretation abilities. In our study we evaluate GPT-4s performance on the American College of Radiology (ACR) 2022 Diagnostic Radiology In-Training Examination (DXIT). MethodsQuestions were sequentially input into GPT-4 with a standardized prompt. Each answer was recorded and overall accuracy was calculated, as was logic-adjusted accuracy, and accuracy on image-based questions. This experiment was repeated several months later to assess for model drift. ResultsGPT-4 achieved 58.5% overall accuracy, lower than the PGY-3 average (61.9%) but higher than the PGY-2 average (52.8%). Adjusted accuracy was 52.8%. GPT-4 showed significantly higher (p = 0.012) confidence for correct answers (87.1%) compared to incorrect (84.0%). Performance on image-based questions was notably poorer (p < 0.001) at 45.4% compared to text-only questions (80.0%), with adjusted accuracy for image questions of 36.4%. When the questions were repeated, GPT-4 chose a different answer 25.5% of the time and there was a small but insignificant decrease in accuracy. DiscussionGPT-4 performed between PGY-2 and PGY-3 levels on the 2022 DXIT, but significantly poorer on image-based questions, and with large variability in answer choices across time points. This study underscores the potential and risks of using minimally-prompted general AI models in interpreting radiologic images as a diagnostic tool. Implementers of general AI radiology systems should exercise caution given the possibility of spurious yet confident responses.

bioinformatics↗

bioRxiv2023

Sequence-independent, site-specific incorporation of chemical modifications to generate light-activated plasmids

Plasmids are ubiquitous in biology, where they are used to study gene-function relationships and intricate molecular networks, and hold potential as therapeutic devices. Developing methods to control their function will advance their application in research and may also expedite their translation to clinical settings. Light is an attractive stimulus to conditionally regulate plasmid expression as it is non-invasive, and its properties such as wavelength, intensity, and duration can be adjusted to minimise cellular toxicity and increase penetration. Herein, we have developed a method to site-specifically introduce photocages into plasmids, by resynthesizing one strand in a manner similar to Kunkel mutagenesis. Unlike alternative approaches to chemically-modify plasmids, this method is sequence independent at the site of modification and uses commercially available phosphoramidites. To generate our light-activated (LA) plasmids, photocleavable biotinylated nucleobases were introduced at specific sites across the T7 and CMV promoters on plasmids and bound to streptavidin to sterically block access. These LA-plasmids were then successfully used to control expression in both cell-free systems (T7 promoter) and mammalian cells (CMV promoter). These light-activated plasmids might be used to remotely-control cellular activity and reduce off-target toxicity for future medical use. Our simple approach to plasmid modification might also be used to introduce novel chemical moieties for advanced function. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=50 SRC="FIGDIR/small/542478v1_ufig1.gif" ALT="Figure 1"> View larger version (12K): org.highwire.dtl.DTLVardef@256978org.highwire.dtl.DTLVardef@2f7ecdorg.highwire.dtl.DTLVardef@2dd957org.highwire.dtl.DTLVardef@1802bf_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2023

Whole transcriptome profiling of placental pathobiology in SARS-CoV-2 pregnancies identifies a preeclampsia-like gene signature

ObjectivesSevere Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus infection in pregnancy is associated with higher incidence of placental dysfunction, referred to by a few studies as a "preeclampsia-like syndrome". However, the mechanisms underpinning SARS-CoV-2-induced placental malfunction are still unclear. Here, we investigated whether the transcriptional architecture of the placenta is altered in response to SARS-CoV-2 infection. MethodsWe utilized whole-transcriptome, digital spatial profiling, to examine gene expression patterns in placental tissues from participants who contracted SARS-CoV-2 in the third trimester of their pregnancy (n=7) and those collected prior to the start of the coronavirus disease 2019 (COVID-19) pandemic (n=9). ResultsThrough comprehensive spatial transcriptomic analyses of the trophoblast and villous core stromal cell subpopulations in the placenta, we identified signatures associated with hypoxia and placental dysfunction during SARS-CoV-2 infection in pregnancy. Notably, genes associated with vasodilation (NOS3), oxidative stress (GDF15, CRH), and preeclampsia (FLT1, EGFR, KISS1, PAPPA2), were enriched with SARS-CoV-2. Pathways related to increased nutrient uptake, vascular tension, hypertension, and inflammation, were also enriched in SARS-CoV-2 samples compared to uninfected controls. ConclusionsOur findings demonstrate the utility of spatially resolved transcriptomic analysis in defining the underlying pathogenic mechanisms of SARS-CoV-2 in pregnancy, particularly its role in placental dysfunction. Furthermore, this study highlights the significance of digital spatial profiling in mapping the intricate crosstalk between trophoblasts and villous core stromal cells, thus shedding light on pathways associated with placental dysfunction in pregnancies with SARS-CoV-2 infection. Graphical abstractIn this study, using spatial digital profiling transcriptomic approaches, we demonstrate that SARS-CoV-2 infection in pregnancy disrupts optimal placental function by altering the genomic architecture of trophoblasts and villous core stromal cells.

developmental biology↗

bioRxiv2022

Distinct pathways of adaptive evolution in Cryptococcus neoformans reveal a point mutation in adenylate cyclase with drastic tradeoffs for pathogenicity

Pathogenic fungi populate a wide range of environments and infect a diversity of host species. Despite this substantial biological flexibility, the impact of interactions between fungi and their hosts on the evolution of pathogenicity remains unclear. We studied how repeated interactions between the fungus Cryptococcus neoformans and relevant environmental and mammalian host cells--amoeba and mouse macrophages--shape the evolution of this model fungal pathogen. First, using a collection of clinical and environmental isolates of C. neoformans, we characterized a range of survival phenotypes for these strains when exposed to host cells of different species. We then performed serial passages of an environmentally isolated C. neoformans strain through either amoeba or macrophages for ~75 generations to observe how these interactions select for improved replication within hosts. In an adapted population, we identified a single point mutation in the adenylate cyclase gene, CAC1, that swept to fixation and confers a strong competitive advantage for growth inside of macrophages. Strikingly, this growth advantage in macrophages is inversely correlated with disease severity during mouse infections, suggesting that adaptations to specific host niches can markedly reduce the pathogenicity of these fungi. These results raise intriguing questions about the influence of cAMP signaling on pathogenicity and highlight the role of seemingly small adaptive changes in promoting fundamental shifts in the intracellular behavior and virulence of these important human pathogens.

microbiology↗

bioRxiv2022

Combinatorial interactions of Hox genes establish appendage diversity of the amphipod crustacean Parhyale hawaiensis

Hox genes establish regional identity along the anterior-posterior axis in diverse animals. Changes in Hox expression can induce striking homeotic transformations, where one region of the body is transformed into another. Previous work in Drosophila has demonstrated that Hox cross-regulatory interactions are crucial for maintaining proper Hox expression. One major mechanism is the phenomenon of "posterior prevalence", wherein anterior Hox genes are repressed by more posterior Hox genes. Loss of posterior Hox expression under this model would predict posterior-to-anterior transformations, as is frequently observed in Drosophila. While posterior prevalence is thought to occur in many animals, studies of such Hox cross-regulation have focused on a limited number of organisms. In this paper, we examine the cross-regulatory interactions of three Hox genes, Ultrabithorax (Ubx), abdominal-A (abd-A), and Abdominal-B (Abd-B) in patterning thoracic and abdominal appendages in the amphipod crustacean Parhyale hawaiensis. Studies of Hox function in Parhyale have previously revealed two striking phenotypes which differed markedly from what a "posterior prevalence" model would predict, including non-contiguous and anterior-to-posterior transformations. We probe the logic of Parhyale Hox cross-regulation by using CRISPR/Cas9 to systematically examine all combinations of Ubx, abd-A, and Abd-B loss of function in Parhyale. By analyzing homeotic phenotypes and examining the expression of additional Hox genes, we reveal Hox cross-regulatory interactions in Parhyale. From these data, we also demonstrate that some Parhyale Hox genes function combinatorially to specify posterior limb identity, rather than abiding by a posterior prevalence mechanism. These results provide evidence that combinatorial Hox interactions may be responsible for the tremendous body plan diversity of crustaceans. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=192 SRC="FIGDIR/small/485717v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@16bfc85org.highwire.dtl.DTLVardef@8f859eorg.highwire.dtl.DTLVardef@8d7892org.highwire.dtl.DTLVardef@1e6c9f0_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2022

Integrated platform for multi-scale molecular imaging andphenotyping of the human brain

Understanding cellular architectures and their connectivity is essential for interrogating system function and dysfunction. However, we lack technologies for mapping the multi-scale details of individual cells in the human organ-scale system. To address this challenge, we developed a platform that simultaneously extracts spatial, molecular, morphological, and connectivity information of individual cells from the same human brain, by integrating novel chemical, mechanical, and computational tools. The platform includes three key tools: (i) a vibrating microtome for ultra-precision slicing of large-scale tissues without losing cellular connectivity (MEGAtome), (ii) a polymer hydrogel-based tissue processing technology for multiplexed multiscale imaging of human organ-scale tissues (mELAST), and (iii) a computational pipeline for reconstructing 3D connectivity across multiple brain slabs (UNSLICE). We demonstrated the transformative potential of our platform by analyzing human Alzheimers disease pathology at multiple scales and demonstrating scalable neural connectivity mapping in the human brain. One-Sentence SummaryWe developed an integrated, scalable platform for highly multiplexed, multi-scale phenotyping and connectivity mapping in the same human brain tissue, which incorporated novel tissue processing, labeling, imaging, and computational technologies.

bioengineering↗

bioRxiv2021

Live imaging of SARS-CoV-2 infection in mice reveals neutralizing antibodies require Fc function for optimal efficacy

Neutralizing antibodies (NAbs) are effective in treating COVID-19 but the mechanism of immune protection is not fully understood. Here, we applied live bioluminescence imaging (BLI) to monitor the real-time effects of NAb treatment in prophylaxis and therapy of K18-hACE2 mice intranasally infected with SARS-CoV-2-nanoluciferase. We could visualize virus spread sequentially from the nasal cavity to the lungs and thereafter systemically to various organs including the brain, which culminated in death. Highly potent NAbs from a COVID-19 convalescent subject prevented, and also effectively resolved, established infection when administered within three days. In addition to direct Fab-mediated neutralization, Fc effector interactions of NAbs with monocytes, neutrophils and natural killer cells were required to effectively dampen inflammatory responses and limit immunopathology. Our study highlights that both Fab and Fc effector functions of NAbs are essential for optimal in vivo efficacy against SARS-CoV-2.

immunology↗

bioRxiv2020

Functional dissection of neural circuitry using a genetic reporter for fMRI

The complex connectivity of the mammalian brain underlies its function, but understanding how interconnected brain regions interact in neural processing remains a formidable challenge. Here we address this problem by introducing a genetic probe that permits selective functional imaging of neural circuit elements defined by their synaptic interrelationships throughout the brain. The probe is an engineered enzyme that transduces cytosolic calcium dynamics of probe-expressing cells into localized hemodynamic responses that can be selectively visualized by functional magnetic resonance imaging. Using a viral vector that undergoes retrograde transport, we apply the probe to characterize a brain-wide network of monosynaptic inputs to the striatum activated in a deep brain stimulation paradigm in rats. The results reveal engagement of surprisingly diverse projection sources and inform an integrated model of striatal function relevant to reward behavior and therapeutic neurostimulation approaches. Our work thus establishes a potent strategy for mechanistic analysis of distributed neural systems.

neuroscience↗

bioRxiv2020

Divergent pallidal pathways underlying distinct Parkinsonian behavioral deficits

The basal ganglia are a group of subcortical nuclei that regulates motor and cognitive functions1,2. Recent identification of neuronal heterogeneity in the basal ganglia suggests that functionally distinct neural circuits defined by their efferent projections exist even within the same nuclei3-5. This distinction may account for a multitude of symptoms associated with basal ganglia disorders such as Parkinsons disease (PD)6,7. However, our incomplete understanding of the basal ganglia functional organization has hindered further investigation of individual circuits that may underlie different behavioral symptoms in disease states. Here we functionally define two distinct classes of parvalbumin-expressing neurons in the mouse external globus pallidus (GPe-PV) embedded within discrete neural pathways and establish their contributions to different Parkinsonian behavioral deficits. We find that GPe-PV neurons projecting to the substantia nigra pars reticulata (SNr) or parafascicular thalamus (PF) undergo different electrophysiological adaptations in response to dopamine depletion. Furthermore, counteracting these adaptations in each population can selectively alleviate movement deficits or behavioral inflexibility in a Parkinsonian mouse model. Our findings provide a novel framework to understand the circuit basis of separate behavioral symptoms in Parkinsonian state which could provide better strategies for the treatment of PD.

neuroscience↗