Biology subjects

Chu, N.

Publications and source records attributed to Chu, N..

10 recordsLinked to original sources

bioRxiv2026

Precocious maturation and Purkinje cell dysfunction in the mouse Chd8 haploinsufficient cerebellum

The cerebellum plays an emerging, but understudied, role in neurodevelopmental disorders (NDDs). Mutations in CHD8 cause a monogenic NDD (CHD8-NDD) characterized by autism and other manifestations, and prior work in Chd8 mutant mice reported cerebellar abnormalities, raising the possibility of cerebellar contribution to CHD8-NDD. To comprehensively characterize the impact of Chd8 haploinsufficiency on cerebellar development and function, we profiled the postnatal day 12 (P12) cerebellum of germline Chd8+/- mice using transcriptomic, morphological, and electrophysiological approaches. Gross cerebellar morphology was unaffected, but single-nucleus RNA sequencing revealed transcriptomic signatures of pathophysiology across cell types, including accelerated maturation of molecular layer interneurons and granule cells, and altered myelination state of oligodendrocytes. Purkinje cells (PCs) showed the strongest transcriptomic burden of any cell type and, consistent with this, exhibited altered morphology and electrophysiological properties. Bulk RNA sequencing confirmed that transcriptomic pathology persists into adulthood, indicating lasting impacts on both neuronal and glial gene expression. Together, these results capture cell-type-specific cerebellar perturbations associated with Chd8 haploinsufficiency and support the cerebellum as a relevant site of pathology in CHD8-NDD.

neuroscience↗

bioRxiv2025

A Human Neuronal Co-Culture System Reveals Early Tumor-Neuron Communication and Targetable Pathways in Glioblastoma

BackgroundGlioblastoma (GB, IDH wild type) is the most aggressive primary brain tumor in adults, with recurrence driven by residual tumor cells that re-establish interaction with surrounding neurons. While neuronal activity is recognized as a driver of GB progression, the earliest neuronal responses to tumor contact remain poorly understood. Existing models rarely capture these acute events or the heterogeneity of responses generated by tumors of different origins, limiting insight into the earliest neuron-tumor interactions. MethodsWe developed a dual-interface human iPSC-derived neuronal culture system to investigate acute neuronal responses to glioblastoma exposure. Neurons were challenged with either established GB cell lines or patient-derived glioblastoma cells (PDGCs). Using quantitative proteomics, high-resolution imaging, and immunological assays, we characterized compartment-specific neuronal changes and mapped activated signaling pathways. We also screened selective inhibitors for their effects on both tumor proliferation and neuronal integrity. FindingsWithin 24 hours of exposure, neurons displayed synaptic remodeling and activation of GB-related signaling cascades. Proteomic analysis of GB exposed neurons revealed enrichment of pathways associated with GB and abnormalities in neuronal circuits. Notably, the U-87MG cell line, but not PDGCs, induced pronounced synaptic disruption, neurite retraction, and MAPK pathway activation, with distinct molecular signatures across neuronal compartments. ERK1/2 and p38 MAPK signaling were differentially activated depending on the GB cells source, correlating with specific structural and functional synaptic alterations. Targeted inhibition of MAPK components significantly suppressed U-87MG proliferation and preserved neuronal architecture. InterpretationWe present a human neuronal culture model that detects and discriminates the earliest neuron-derived responses to glioblastoma from diverse tumor sources. By linking neuronal remodeling to tumor-specific signaling pathways, the platform uncovers both the heterogeneity of neuron-tumor interactions and early, targetable vulnerabilities. This system offers a translational tool to advance understanding of GB recurrence and to guide development of therapies with dual neuroprotective and anti-tumor efficacy. In BriefEarly interactions between glioblastoma and human neurons drive rapid, source-specific synaptic remodeling mediated by compartmental MAPK pathway activation. This neuronal co-culture model identifies distinct profiles of tumor-neuron communication, highlights synaptic vulnerability as a therapeutic axis, and demonstrates that MAPK pathway inhibition yields both neuroprotective and anti-tumor effects. SummaryGlioblastoma (GB) co-opts neuronal circuits to drive tumor progression, yet the earliest neuronal responses that may shape recurrence remain poorly defined. We developed a human iPSC-derived neuronal co-culture model that captures acute communication between neurons and glioblastoma from diverse sources, including serum-adapted cell lines and patient-derived cells. Within 24 hours, glioma-exposed neurons exhibited synaptic remodeling and activation of tumor-associated signaling pathways. High-resolution imaging and proteomics revealed compartment-specific synaptic alterations, with ERK1/2 and p38 MAPK signaling differentially engaged depending on the tumor source, corresponding to distinct structural and functional outcomes. Pharmacologic inhibition of MAPK components both suppressed tumor cells growth and preserved neuronal integrity. By modeling source-dependent and early neuron-tumor interactions, this platform not only identifies MAPK signaling as a critical mediator of synaptic vulnerability but also provides a clinically relevant tool for investigating the mechanisms of glioblastoma recurrence. It offers a framework for developing therapies that target the dual vulnerabilities of tumor progression and circuit remodeling. Highlights O_LIA dual-interface human iPSC-derived neuronal co-culture system models early neuron-glioblastoma (GB) interaction. C_LIO_LISerum-adapted U-87MG, but not serum-free patient-derived GB cells, induces pronounced synaptic disruption and neurite retraction. C_LIO_LIGlobal proteome of neurons reveals GB-associated signatures and neuronal circuit alterations in response to both U-87MG and patient-derived GB cells. C_LIO_LIERK1/2 and p38 MAPK signaling are differentially activated in neuronal compartments, depending on GB source. C_LIO_LIMAPK pathway inhibition suppresses U-87MG proliferation and preserves neuronal integrity, revealing actionable neuroprotective and anti-tumor targets. C_LI

cancer biology↗

bioRxiv2025

Intrinsic higher potency of basal urothelial cells to intermediate and umbrella cells as the cell of origin for bladder cancer

Transcriptome profiling of bladder cancer has revealed distinct basal-like and luminal-like molecular subtypes, which may be correlated with pathological subtypes of different patient outcomes. However, whether these molecular subtypes originate from the corresponding cell types in the normal urothelium and whether different cells of origin influence bladder cancer progression remain unclear. Here, we conducted cell-type-specific lineage tracing in CRISPR/Cas9-induced mouse bladder cancer models of Pten and Trp53 targeting. We show that although basal, intermediate, and superficial umbrella cells can all serve as the cell of origin for bladder cancer, transformed umbrella cells were gradually displaced by tumor cells from inner layers, particularly transformed basal cells, which had highest stemness. Histological and single cell RNA-sequencing data comparing basal- and intermediate-cell-induced bladder tumors revealed that basal-induced tumors displayed higher heterogeneity, and contained unique cell clusters including Krt14+Ki67+ highly proliferative basal cells, squamous cell carcinoma, and transitioning cells towards the Gata3+ luminal subtype. Trajectory analysis confirmed the cell lineage differentiation hierarchy uncovered in lineage tracing. Moreover, human bladder cancer molecular subtype signatures were highly enriched in mouse tumor cell clusters of the corresponding cell of origin, and a gene signature derived from the unique basal-induced clusters is predictive of worse patient outcome. Overall, our results support that the basal and luminal molecular subtypes of bladder cancer have the corresponding cells of origin as their basis, and that urothelial basal cells are intrinsically more competitive than intermediate and umbrella cells in generating aggressive bladder cancer subtypes.

cancer biology↗

bioRxiv2025

Persistent cortical excitatory neuron dysregulation in adult Chd8 haploinsufficient mice.

CHD8 mutations cause autism spectrum disorder, cognitive deficits, and macrocephaly. Chd8+/- mouse models exhibit macrocephaly and transcriptional pathology, with inconsistent findings regarding neurogenesis, neuron function, and behavior. Via stereology and single nucleus transcriptomics (snRNA-seq), we found increased Chd8+/- cortical volume was not explained by increase in neuron number. Differential expression (DE) was present across cortical cell types, with excitatory neurons exhibiting high DE burden and shared and subclass-specific DE signatures. Bulk RNA-seq DE of constitutive Chd8+/- and conditional Camk2a-Cre Chd8+/-mice identified shared transcriptional pathology. DE in synaptosomal versus nuclear mRNA identified overlapping DEGs, but also significant differences and exaggerated synaptosomal changes. Building on DE findings implicating glutamatergic neurons, we found Chd8+/-mice exhibited altered excitatory neuron spine density and dynamics, decreased GCaMP activity correlation, and sleep perturbation. Thus, Chd8 haploinsufficiency causes lasting excitatory neuron dysfunction, perturbs RNA regulation beyond transcription, and impacts neuronal properties, cortical microcircuits, and behavior.

genomics↗

bioRxiv2024

Distribution of contezolid in different tissues of mice and human patients infected with Mycobacterium abscessus

BackgroundLinezolid (LZD), while effective against Mycobacterium abscessus (MAB), can cause myelosuppression and peripheral neuropathy. Contezolid (CZD) shares a similar antimicrobial profile with improved safety, but biodistribution data remain limited. This study evaluated CZDs biodistribution in MAB-infected mice and humans and its therapeutic potential across infection sites. MethodsMICs of CZD and LZD against 32 clinical MAB isolates and three reference strains were determined. In MAB-infected mice, drug concentrations were quantified in plasma and pulmonary and cerebral tissues at 2, 4, and 8 hours post-administration. In MAB-infected patients, CZD concentrations in bone, plasma, and cerebrospinal fluid were measured at multiple time points and MAB counts in sputum cultures were assessed daily over 14 days. ResultsRespective MIC50 and MIC90 values were 8 and 32 {micro}g/mL (LZD) and 16 and 32 {micro}g/mL (CZD). Pharmacokinetic CZD and LZD level comparisons revealed peak CZD plasma levels within 2 hours, higher systemic CZD levels, comparable pulmonary tissue concentrations, and slightly lower CZD cerebral tissue penetration. In patients, CZD levels in ankle joint effusion samples reached 2.0885 {micro}g/mL at 6 hours, peaking in the posterior malleolus. Plasma CZD concentrations peaked at 8.2349 {micro}g/mL at 3 hours and dropped to 6.1065 {micro}g/mL by 6 hours, while CSF levels were 0.9295 and 0.792 {micro}g/mL at 3 and 6 hours, respectively. Sputum bacterial burden decreased rapidly within 24 hours of CZD treatment, with near-complete clearance by day 4. ConclusionCZD and LZD exhibit comparable tissue distribution but different site-specific penetration, supporting their potential for treating diverse MAB infections.

microbiology↗

bioRxiv2023

Transcription Factor NRF2 is Activated by Erythrophagocytosis of Oxidized Red Blood Cell Products and Suppresses the IL-12-IFNg-IL-10 Axis in a Murine Model of Hyperinflammatory Disease

Hyperinflammatory diseases including macrophage activation syndrome (MAS) and hemophagocytic lymphohistocytosis (HLH) are characterized by multi-lineage cytopenias, hypercytokinemia, and tissue hemophagocytosis. However, the mechanisms by which erythrophagocytosis mediates iron metabolism and regulates the hyperactive immune response remain unclear. The transcription factor NRF2 is an important sensor for inflammatory and redox distress. The targets of NRF2 are antioxidant response elements responsible for transcription of genes related to restoration of redox homeostasis within the cell. Here we demonstrate that mice with CpG-induced MAS have evidence of systemic oxidative and nitrosative distress - including increased serum nitric oxide and elevated systemic lipid peroxidation. In this model, NRF2 knockout mice develop significantly worse organomegaly, hypercytokinemia, and reticulocytosis. NRF2 knockout mice have unexpected exacerbation in the cytokines that are central to hyperinflammatory physiology - namely IL-12, IFN gamma (IFNg), and IL-10. In vitro we demonstrate that oxidized red blood cell products and heme itself suppress IL-12 protein production and transcription from bone marrow derived dendritic cells in a NRF2-dependent manner. Together our studies demonstrate that erythrophagocytosis of oxidized red blood cell products suppresses the Il-12-IFNg-IL-10 axis which drives hyperinflammation in murine hyperinflammation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/571271v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1a2330corg.highwire.dtl.DTLVardef@1c59944org.highwire.dtl.DTLVardef@1d151b5org.highwire.dtl.DTLVardef@14b4301_HPS_FORMAT_FIGEXP M_FIG C_FIG Created with BioRender

immunology↗

bioRxiv2022

PH Domain-Mediated Autoinhibition and Oncogenic Activation of Akt

Previously, we reported that the conformation of autoinhibited Akt, a Ser/Thr protein kinase that plays a central role in metabolism and cancer, may be shifted by small molecule allosteric inhibitors limiting the mechanistic insights from existing X-ray structures that have relied on such compounds (Chu, Viennet, et al, 2020). Here we discover unexpectedly that a single mutation, R86A, in Akts PH domain exhibits intensified autoinhibitory features with enhanced PH domain-kinase domain affinity. Structural and biochemical analysis uncovers the importance of a key interaction network involving Arg86, Glu17, and Tyr18 that controls Akt conformation and activity. Our studies also shed light on the molecular basis for E17K Akt activation as an oncogenic driver.

biochemistry↗

bioRxiv2021

A cerebellar-prepontine circuit for tonic immobility triggered by inescapable threat

Sudden changes in the sensory environment are frequently perceived as threats and may provoke defensive behavioral states. One such state is tonic immobility, a conserved defensive strategy characterized by a powerful suppression of movement and motor reflexes. Tonic immobility has been associated with multiple brainstem regions and cell types, but the underlying circuit is not known. Here, we demonstrate that a strong vibratory stimulus evokes tonic immobility in larval zebrafish defined by suppression of exploratory locomotion and sensorimotor responses. Using a circuit-breaking screen and targeted neuron ablations, we show that cerebellar granule cells and a cluster of glutamatergic ventral prepontine neurons (vPPNs) that express key stress-associated neuropeptides are critical components of the circuit that suppresses movement. The complete sensorimotor circuit transmits information from primary sensory neurons through the cerebellum to vPPNs to regulate reticulospinal premotor neurons. These results show that cerebellar regulation of a neuropeptide-rich prepontine structure governs a conserved and ancestral defensive behavior that is triggered by inescapable threat.

neuroscience↗

bioRxiv2020

Elucidation of remdesivir cytotoxicity pathways through genome-wide CRISPR-Cas9 screening and transcriptomics

The adenosine analogue remdesivir has emerged as a frontline antiviral treatment for SARS-CoV-2, with preliminary evidence that it reduces the duration and severity of illness1. Prior clinical studies have identified adverse events1,2, and remdesivir has been shown to inhibit mitochondrial RNA polymerase in biochemical experiments7, yet little is known about the specific genetic pathways involved in cellular remdesivir metabolism and cytotoxicity. Through genome-wide CRISPR-Cas9 screening and RNA sequencing, we show that remdesivir treatment leads to a repression of mitochondrial respiratory activity, and we identify five genes whose loss significantly reduces remdesivir cytotoxicity. In particular, we show that loss of the mitochondrial nucleoside transporter SLC29A3 mitigates remdesivir toxicity without a commensurate decrease in SARS-CoV-2 antiviral potency and that the mitochondrial adenylate kinase AK2 is a remdesivir kinase required for remdesivir efficacy and toxicity. This work elucidates the cellular mechanisms of remdesivir metabolism and provides a candidate gene target to reduce remdesivir cytotoxicity.

genetics↗

bioRxiv2019

Moxifloxacin efficacy against Mycobacterium abscessus in vivo using zebrafish model

Moxifloxacin (MFX) showed good activity in vitro against Mycobacterium abscessus (M. abscessus) and was suggested as one of the antibiotic regimens for adults with M. abscessus disease. However, some other studies showed that MFX showed less or none activity against M. abscessus. In our study we aim to evaluate MFX activity against M. abscessus using zebrafish (ZF) model in vivo. MIC of each drugs were determined by broth microdilution method. M. abscessus labeled by CM-DiI, were micro-injected into ZF. Survival curves were determined by recording dead ZF every day. After 4 days of incubation ZF were lysed. Colony-forming unit (CFU) were enumerated and results are expressed as mean log10 CFU per ZF. Bacteria dissemination and fluorescence intensity in ZF were observed and analyzed. Inhibition rate was also calculated. In our study MFX showed good activity in vitro. But in vivo MFX showed limited restriction to M. abscessus. The association between increased survival and high dose of MFX is not significant. Same results were observed in bacterial fluorescence intensity and inhibition rates, with no significant difference when compared with no drug group (P > 0.05). However, significant difference was observed in azithromycin (AZM) group. MFX showed limited efficacy on Mycobacterium abscessus in vivo using ZF model. MFXs activity in vivo need to be confirmed.

microbiology↗