Biology subjects

Lim, K.

Publications and source records attributed to Lim, K..

At least 19 recordsLinked to original sources

bioRxiv2026

Nuclear Pct1 couples phosphatidylcholine synthesis with membrane biogenesis

Phosphatidylcholine (PC) is the major eukaryotic phospholipid and its synthesis must be homeostatically controlled to prevent excess membrane and organelle growth. Here we investigate how PC synthesis by the Kennedy pathway is coordinated with membrane biogenesis. In budding yeast, the rate-limiting enzyme Pct1 is nuclear and reversibly associates with the inner nuclear membrane (INM) in response to lipid packing defects caused by low PC. We show that the enzymes acting after Pct1 to generate PC remain at the endoplasmic reticulum (ER) during pathway activation. Relocating the final PC synthesis step to different endomembrane sites does not alter the kinetics of Pct1 release from the INM, indicating that newly made PC equilibrates with the INM rapidly. In contrast, elevated phosphatidic acid locks Pct1 at the INM, prevents pathway inactivation and drives nuclear/ER membrane proliferation. These results support a model in which nuclear Pct1 senses lipid imbalance while ER-localized enzymes supply PC; disrupting this homeostasis leads to uncontrolled membrane biogenesis.

cell biology↗

bioRxiv2026

Do drugs with biliary toxicity cause cholangiocarcinoma?

AO_SCPLOWBSTRACTC_SCPLOWMany commonly used therapeutic drugs cause biliary toxicity, but it is unclear if they are directly responsible for the increasing incidence of cholangiocarcinoma (CCA). We tested experimentally and analyzed through a cohort approach whether drugs, such as the commonly used antibiotic Augmentin, which is a poster-child of biliary toxicity, are causally linked to CCA development. Using sophisticated analytical tools in cholangiocytes, including single extracellular vesicle (EV) analysis, we found no evidence that Augmentin increases the cholangiocyte malignancy marker YAP1 or phospho-YAP1. Furthermore, we analyzed the CCA incidence in our healthcare system and determined it to be 0.0932% (Augmentin group) and 0.0799% (amoxicillin control group). Although the Augmentin group showed a numerically higher CCA incidence, the association did not reach statistical significance (RR = 1.1669, 95% CI 0.6200-2.1961; Fishers exact test, P = 0.7493). Similarly, we found no evidence for cholangiocarcinoma development with other commonly used drugs, including chlorpromazine, floxuridine, 5-fluorouracil, flucloxacillin and terbinafine. We conclude that there is no direct causal relationship between clinical Augmentin doses and CCA development.

cancer biology↗

bioRxiv2025

Neuroanatomical Correlates of Negative Symptoms in Schizophrenia

BackgroundSchizophrenia is characterized by widespread structural brain abnormalities, but associations between structural abnormalities and negative symptom severity are not well understood. Negative symptoms have been conceptualized in a hierarchical structure of two second-order dimensions--motivation and pleasure (MAP) and expression (EXP)--and five first-order domains: anhedonia, avolition, and asociality (MAP), and blunted affect and alogia (EXP). A better understanding of the neural circuitry underlying negative symptom dimensions and domains is important given their reported association with poor functional outcome and lack of available treatments. Study DesignThe meta-analysis included 1,591 individuals with schizophrenia across 16 samples with structural imaging and Scale for Assessment of Negative Symptoms data. The study generated correlations of cortical thickness and subcortical volumes with the negative symptom dimensions and domains. Study resultsNegative symptoms showed mainly negative associations with cortical thickness and subcortical volumes. The effect sizes were small but there was a pattern of associations in predominantly frontal lobe cortical thickness and limbic subcortical volumes. The regional correlation patterns of cortical thickness and subcortical volumes with symptom domains support the conceptualized hierarchical structure of negative symptoms: correlations of MAP domains were stronger with the MAP than EXP dimension, and vice versa. Exploratory analyses with receptor densities further supported the hierarchy. ConclusionOur findings reveal small but consistent associations between negative symptom dimensions and predominantly prefrontal region cortical thickness, and limbic region volumes. These findings advance our understanding of the network of anatomical regions that may contribute to the severity of negative symptoms in schizophrenia.

neuroscience↗

bioRxiv2025

Endogenous gene editing of alveolar organoids reveals that expression of pathogenic variant SFTPC-I73T disrupts endosomal function, epithelial polarity and wound healing

BackgroundIdiopathic pulmonary fibrosis is a fatal lung disease of progressive lung parenchymal scarring caused by the aberrant response of an alveolar epithelium repeatedly exposed to injury. Understanding epithelial dysfunction has been hampered by the lack of physiological alveolar type 2 (AT2) cell models and defined disease triggers. Monogenic forms of familial pulmonary fibrosis (FPF) caused by toxic gain-of-function variants provide an opportunity to investigate early pathogenic events. One such variant, surfactant protein C (SFTPC)-I73T, abnormally localises within AT2 cells and causes their dysfunction. MethodsWe used base editing of fetal lung-derived AT2 (fdAT2) organoids to create a heterozygous disease model of endogenous SFTPC-I73T expression. We also created an inducible overexpression system to interrogate temporal changes associated with SFTPC-I73T expression. We cultured fdAT2 both in 3D culture and at air-liquid interface to understand the importance of polarity cues and air exposure on disease phenotypes. ResultsIn our heterozygous endogenous expression system, we found that fdAT2 expressing SFTPC-I73T grew without a lumen and were unable to correctly polarise. SFTPC-I73T accumulated with time and caused gross enlargement of early endosomes, preventing correct apico-basal trafficking of multiple endosomally trafficked cargoes including polarity markers and cell adhesion proteins. This phenotype was exacerbated by air exposure and led to loss of epithelial monolayer integrity and abnormal wound healing after injury. ConclusionUsing endogenous gene editing for the first time in differentiated alveolar organoids, we have demonstrated that the pathogenic effects of SFTPC-I73T are mediated through endosomal dysfunction and abnormal epithelial organisation. This has important implications for AT2 function in vivo.

cell biology↗

bioRxiv2025

Mitochondrial DNA Mutations Determine Favourable Molecular Responses to Targeted Kinase Inhibitor Therapy and Impair Oxidative Phosphorylation

Somatic mutations in mitochondrial DNA (mtDNA) are not typically considered key oncogenic drivers of cancer, primarily because of a high synonymous to non-synonymous variant ratio. Here, we surveyed 248 matched diagnosis and remission samples from patients with chronic myeloid leukemia (CML) and found a 75% had mitochondrial mutations with a median number of 2 mutations per patient. mtDNA mutations were predominantly non-synonymous, enriched in the D-loop control region, and likely originated from replication and transcriptional errors. Functionally, mtDNA mutations were associated with reduced oxidative phosphorylation (OXPHOS), as measured by Seahorse analyser. This metabolic vulnerability could be phenocopied by treatment with the complex I inhibitor IACS-10759 in combination with the targeted tyrosine kinase inhibitor (TKI) imatinib, which significantly reduced the colony-forming potential of TKI resistant leukemic stem/progenitor cells (LSPCs). Strikingly, we show that mtDNA mutations were associated with increased sensitivity to imatinib therapy in the clinic. Patients with [≥]3 mutations and patients with mutations in the D-loop showed significantly higher cumulative incidence of major molecular response at 24 months (90% vs. 68%, p = 0.004, and 89% vs 68%, p = 0.004 respectively). Single-cell RNA sequencing further revealed enrichment in non-synonymous mtDNA variants in LSPCs from TKI-sensitive patients, while TKI-resistant cells exhibited upregulated gene signatures related to glycerolipid and phospholipid metabolism and mitochondrial biogenesis. Together, our findings demonstrate that mtDNA mutations are key determinants of sensitivity to targeted therapy, rather than oncogenic drivers of leukemogenesis. Mechanistically, non-synonymous mtDNA mutations appear to restrict mitochondrial metabolic plasticity, with widespread implications for precision oncology.

cancer biology↗

bioRxiv2025

Neural signaling contributes to heart formation and growth in the invertebrate chordate, Ciona robusta.

Neurons contribute to the complex interplay of signals that mediate heart development and homeostasis. Although a limited set of studies suggest that neuronal peptides impact vertebrate heart growth, the specific contributions of these peptides to cardiomyocyte progenitor differentiation or proliferation have not been elucidated. Here we show that the neuropeptide tachykinin along with canonical Wnt signaling regulate cardiomyocyte progenitor proliferation in the chordate model Ciona robusta. In C. robusta, the heart continues to grow throughout adulthood and classic histological studies indicate that a line of undifferentiated cells may serve as a reserve progenitor lineage. We found that this line of cardiomyocyte progenitors consists of distinct distal and midline populations. Distal progenitors divide asymmetrically to produce distal and midline daughters. Midline progenitors divide asymmetrically to produce myocardial precursors. Through single cell RNA sequencing (scRNA-seq) of adult C. robusta hearts, we delineated the cardiomyocyte progenitor expression profile. Based on this data we investigated the role of Wnt signaling in cardiomyocyte progenitor proliferation and found that canonical Wnt signaling is required to suppress excessive progenitor proliferation. The scRNA-seq data also identified a number of presumptive cardiac neural-like cells. Strikingly, we found that a subset of these neuronal cells appears to innervate the distal cardiomyocyte progenitors. Based on the expression of the tachykinin receptor in these neuronal cells, we blocked tachykinin signaling using pharmacological inhibitors and found that this drove reduced proliferation in the distal progenitor pool. Through targeted CRISPR-Cas9 knockdown we then demonstrated that both extrinsic tachykinin and intrinsic, cardiac tachykinin receptors are required for formation of the myocardial heart tube. This work provides valuable insights into how organisms may deploy neural signals to regulate organ growth in response to environmental or homeostatic inputs.

developmental biology↗

bioRxiv2025

Machine Learning-Driven fMRI Analysis for Objective Craving Prediction

BackgroundCraving is a fundamental aspect of substance use disorder (SUD), traditionally assessed through subjective self-report measures. To develop more objective assessments, we created a brain-based marker to predict craving based on machine learning approaches using functional magnetic resonance imaging (fMRI) drug cue reactivity data from 69 participants with methamphetamine use disorders. MethodsTo predict craving intensity, our analysis demonstrated that utilizing principal component analysis (PCA) and linear regression outperformed other models in terms of Root Mean Squared Error (RMSE). Employing a 5-fold cross-validation strategy with a 20% holdout set, we established the reliability of the model. Additionally, the model successfully classified high and low craving levels and distinguished cue types (neutral vs. drug) based on fMRI data. ResultsThe model achieved an RMSE of 0.983 {+/-} 0.026 (standard deviation), with strong generalization evidenced by an out-of-sample RMSE of 0.985 and statistical significance (p < 0.026; effect size (Cliffs Delta) = 0.715; statistical power = 0.639). Key neurobiological signatures included the Parahippocampal Gyrus, Superior Temporal Gyrus, Medioventral Occipital Cortex, and Amygdala (positively associated with craving), as well as the Inferior Temporal Gyrus (negatively associated). Classification of high vs. low craving levels yielded an AUC-ROC of 0.684 {+/-} 0.084 (out-of-sample AUC-ROC = 0.714), with significant separation (p < 0.04; Cliffs Delta = 0.831). Additionally, classification of cue types (neutral vs. drug) achieved an AUC-ROC of 0.692 {+/-} 0.090 (out-of-sample AUC-ROC = 0.693), with p < 0.002, Cliffs Delta = 0.896, and statistical power = 0.800, highlighting the robustness of the model. ConclusionThese findings underscore the potential of neuroimaging and machine learning to provide objective, data-driven insights into the neural mechanisms underlying subjective experience of craving and to inform future clinical applications in SUD.

neuroscience↗

bioRxiv2025

Electrochemical Metabolic Profiling Reveals Mitochondrial Hyperactivation and Enhanced Neural Progenitor Proliferation in MLC1-Mutant Human Cortical Organoids

Mitochondrial function is critical for neural progenitor regulation, yet its dysregulation during early human brain development remains poorly defined. Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a neurodevelopmental disorder caused by MLC1 mutations, previously attributed to postnatal astrocyte dysfunction. Using patient-derived human cortical organoids, we show that MLC1 is expressed in early neuroepithelial cells. To assess mitochondrial state in live organoids, we developed the MAGO (Matrigel-coated gold nanostructure) platform for real-time, label-free detection of redox activity. MLC1 mutant organoids showed mitochondrial hyperactivation, increased ATP and ROS, reduced membrane potential, and altered fusion protein expression. These changes were accompanied by enhanced BrdU incorporation and expansion of PAX6/SOX2 progenitors. To assess the causal role of MLC1 mutation, we generated isogenic organoids using CRISPR prime editing, which recapitulated redox hyperactivation and increased proliferation. Our findings redefine MLC as a disorder of early mitochondrial and progenitor dysregulation and establish a tractable platform to study metabolic mechanisms in neurodevelopmental disease.

neuroscience↗

bioRxiv2025

Mechanistic basis for protection against fatty liver disease by CIDEB loss-of-function mutations

Background & AimsSomatic and germline CIDEB mutations are associated with protection from chronic liver diseases. The mechanistic basis and whether CIDEB suppression would be an effective therapy against fatty liver disease remain unclear. Methods21 CIDEB somatic mutations were introduced into cells to assess functionality. In vivo screening was used to trace Cideb mutant clones in mice fed normal chow, western (WD), and choline-deficient, L-amino acid-defined, high-fat (CDA-HFD) diets. Constitutive and conditional Cideb knockout mice were generated to study Cideb in liver disease. Isotope tracing was used to evaluate fatty acid oxidation and de novo lipogenesis. Transcriptomics, lipidomics, and metabolic analyses were utilized to explore molecular mechanisms. Double knockout models (Cideb/Atgl and Cideb/Ppara) tested mechanisms underlying Cideb loss. ResultsMost CIDEB mutations showed that they impair function, and lineage-tracing showed that loss-of-function clones were positively selected with some, but not all fatty liver inducing diets. Cideb KO mice were protected from WD, CDA-HFD, and alcohol diets, but had the greatest impact on CDA-HFD induced liver disease. Hepatocyte-specific Cideb deletion could ameliorate disease after MASLD establishment, modeling the impact of therapeutic siRNAs. Cideb loss protected livers via increased {beta}-oxidation, specifically through ATGL and PPARa activation. ConclusionsCideb deletion is more protective in some types of fatty liver disease. {beta}-oxidation is an important component of the Cideb protective mechanism. CIDEB inhibition represents a promising approach, and somatic mutations in CIDEB might predict the patient populations that might benefit the most.

physiology↗

bioRxiv2024

Inhibiting heme-piracy by pathogenic Escherichia coli using de novo-designed proteins

Iron is an essential nutrient for most bacteria and is often growth-limiting during infection, due to the host sequestering free iron as part of the innate immune response. To obtain the iron required for growth, many bacterial pathogens encode transporters capable of extracting the iron-containing cofactor heme directly from host proteins. Pathogenic E. coli and Shigella spp. produce the outer membrane transporter ChuA, which binds host hemoglobin and extracts its heme cofactor, before importing heme into the cell. Heme extraction by ChuA is a dynamic process, with the transporter capable of rapidly extracting heme from hemoglobin in the absence of an external energy source, without forming a stable ChuA-hemoglobin complex. In this work, we utilise a combination of structural modelling, Cryo-EM, X-ray crystallography, mutagenesis, and phenotypic analysis to understand the mechanistic detail of this process. Based on this understanding we utilise artificial intelligence-based protein design to create binders capable of inhibiting E. coli growth by blocking hemoglobin binding to ChuA. By screening a limited number of these designs, we identify several binders that inhibit E. coli growth at low nanomolar concentrations, without experimental optimisation. We determine the structure of a subset of these binders, alone and in complex with ChuA, demonstrating that they closely match the computational design. This work demonstrates the utility of de novo-designed proteins for inhibiting bacterial nutrient uptake and uses a workflow that could be applied to integral membrane proteins in other organisms.

biochemistry↗

bioRxiv2024

Functional Ultrasound Imaging Reveals Activation Properties of Clinical Spinal Cord Stimulation

ObjectivesSpinal cord stimulation (SCS) therapy has long been established as an effective treatment for chronic neuropathic pain. However, methodological limitations have prohibited the detailed investigation of the activation patterns produced in the spinal cord during therapy. Functional ultrasound (fUS) is an emerging technology that monitors local hemodynamic changes in the brain that are tightly coupled to neural functional activity [1-3]. Previous studies have demonstrated that the high sensitivity and spatiotemporal resolution of fUS can be used to monitor activation in the spinal cord [4, 5]. In this study, fUS was used to investigate neuromodulation patterns produced by clinical SCS paradigms in an ovine model that enabled testing with implanted clinical hardware. Materials and MethodsActivation of local dorsal horn regions during SCS therapy was evaluated using fUS to detect hemodynamic changes in flowing spinal blood volume ({Delta}SBV). Briefly, male ovine subjects were anesthetized and laminectomies were performed at T12-L1 to expose the spinal cord. The spine was mechanically fixed to reduce breathing-induced motion. Standard SCS leads were percutaneously implanted midline overlying the dura of the exposed cord to enable stimulation and recording. A second lead was implanted in the epidural space anterior to the laminectomy for recording evoked compound action potentials (eCAPs). Motor thresholds were determined from electromyographic (EMG) signals recorded from subdermal needle electrodes. Hemodynamic activation patterns produced by SCS therapy were mapped across two vertebral segments in the superficial dorsal horn (SDH) at amplitudes between 100%-200% eCAP threshold (eCAPT). The magnitude and volume of significant {Delta}SBV during SCS was quantified and compared across conditions. ResultseCAP and motor thresholds varied widely between different representative SCS programs in current clinical use. Compared with motor threshold, we found eCAPT to be a more stable and reliable ratiometric reference to establish neural drive from stimulation, consistent with previous literature [6]. SCS stimulation resulted in significant activation of the SDH in differing patterns across two vertebral segments. The magnitude and volume of {Delta}SBV increased at higher amplitudes and was typically maximal in the SDH regions underlying the active electrodes. Activation persisted for several seconds following SCS therapy cessation, suggesting the engagement of neurophysiological processes with correspondingly long time constants. In addition, therapy mode significantly influenced total area and depth of {Delta}SBV. Multiphase therapy produced a larger area of {Delta}SBV that extended deeper into the spinal cord relative to single phase therapies. ConclusionsThis work demonstrates that fUS can effectively measure SCS neural response patterns in the pain processing laminae of a large animal model implanted with a clinical SCS system. Hemodynamic responses in the spinal cord varied significantly across SCS therapy modes, with Multiphase stimulation providing a greater area of coverage and depth of response versus other common stimulation types.

neuroscience↗

bioRxiv2024

Evaluating Physiological Indicators in Detecting Deception using the Comparison Question Test (CQT)

Despite significant advancements in deception detection, traditional methods often fall short in real-world applications. This study addresses these limitations by evaluating the effectiveness of various physiological measures -- pupil response, electrodermal activity (EDA), heart rate (HR), and facial temperature changes -- in predicting deception using the Comparison Question Test (CQT). It also fills a critical research gap by validating these methods within an Asian context. Employing a between-subjects design, data was collected from a diverse sample of 118 participants from Singapore, including Chinese, Indian, and Malay individuals. The research aims to identify which physiological indicators, in combination, offer the most robust predictions of deceptive behavior. Key innovations include the adaptation of the CQT with a modified directed lie paradigm and an expanded sample size to assess the relative importance of each physiological measure. The studys findings reveal that pupil response is the most significant predictor of deception, with EDA enhancing the models explanatory power. HR, while relevant, adds limited value when combined with pupil response and EDA, and facial temperature changes were statistically non-significant. The study highlights the need for further research into the interactions among physiological measures and their application in varied contexts. This research contributes valuable insights into improving deception detection methodologies and sets the stage for future investigations that could incorporate additional physiological indicators and explore real-world applications.

bioengineering↗

bioRxiv2024

Neutrophils exposed to a cholesterol metabolite secrete extracellular vesicles that promote epithelial-mesenchymal transition and stemness in breast cancer cells.

Small extracellular vesicles (sEVs) are emerging as critical mediators of intercellular communication in the tumor microenvironment (TME). Here, we investigate the mechanisms by which sEVs derived from neutrophils treated with the cholesterol metabolite, 27-hydroxycholesterol (27HC), influence breast cancer progression. sEVs released from 27HC treated neutrophils enhance epithelial-mesenchymal transition (EMT) and stem-like properties in breast cancer cells, resulting in loss of adherence, increased migratory capacity and resistance to cytotoxic chemotherapy. Decreased microRNAs (miRs) within the sEVs resulted in activation of the WNT/{beta}-catenin signaling pathway in recipient cells and suggest that this may be a predominant pathway for stem-like phenotype and EMT. Our findings underscore a novel mechanism by which 27HC-modulated neutrophils contribute to breast cancer pathophysiology through EV-mediated intercellular communication, suggesting potential therapeutic targets in cancer treatment.

cancer biology↗

bioRxiv2024

Loss of MEF2C function by enhancer mutation leads to neuronal mitochondria dysfunction and motor deficits in mice

Genetic changes and epigenetic modifications are associated with neuronal dysfunction in the pathogenesis of neurodegenerative disorders. However, the mechanism behind genetic mutations in the non-coding region of genes that affect epigenetic modifications remains unclear. Here, we identified an ALS-associated SNP located in the intronic region of MEF2C (rs304152), residing in a putative enhancer element, using convolutional neural network. The enhancer mutation of MEF2C reduces own gene expression and consequently impairs mitochondrial function in motor neurons. MEF2C localizes and binds to the mitochondria DNA, and directly modulates mitochondria-encoded gene expression. CRISPR/Cas-9-induced mutation of the MEF2C enhancer decreases expression of mitochondria-encoded genes. Moreover, MEF2C mutant cells show reduction of mitochondrial membrane potential, ATP level but elevation of oxidative stress. MEF2C deficiency in the upper and lower motor neurons of mice impairs mitochondria-encoded genes, and leads to mitochondrial metabolic disruption and progressive motor behavioral deficits. Together, MEF2C dysregulation by the enhancer mutation leads to mitochondrial dysfunction and oxidative stress, which are prevalent features in motor neuronal damage and ALS pathogenesis. This genetic and epigenetic crosstalk mechanism provides insights for advancing our understanding of motor neuron disease and developing effective treatments.

neuroscience↗

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

mTOR dysregulation induces IL6 and paracrine AT2 cell senescence impeding lung repair in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease which causes lung cysts and respiratory failure. TSC2 deficient LAM cells with dysregulated mTOR signalling form nodules with fibroblasts causing lung injury. We examined if mTOR dysregulation could induce senescence and impair responses to lung injury. Senescence markers p21 and p16 were increased in LAM lungs and co-localised with alveolar type 2 cells. The SenMayo senescence gene panel was upregulated in LAM alveolar type 2 cells with senescence supressed by mTOR inhibition in patients. LAM cell / fibroblast spheroid cultures induced senescence markers in alveolar type 2 cell organoids, altered their growth and delayed epithelial scratch wound repair. Upstream regulator analysis predicted alveolar type 2 cell IL6 receptor activation. IL6 was produced by LAM cells, induced p16 and p21 in alveolar type 2 cells, inhibited epithelial wound resolution and was overexpressed in LAM patient serum where it was related to lung function. Wound repair in the presence of TSC2 null LAM cell / fibroblast spheroids was enhanced by the IL6 receptor antagonist Tocilizumab. Our findings show TSC2 loss induces senescence and IL6 production which are associated with impaired lung repair. Targeting IL6 signalling in parallel with mTOR inhibition, may reduce lung damage in LAM.

cell biology↗

bioRxiv2023

A dual-pathway architecture enables chronic stress to promote habit formation

Chronic stress can change how we learn and, thus, how we make decisions. Here we investigated the neuronal circuit mechanisms that enable this. Using a multifaceted systems neuroscience approach in male and female mice, we reveal a dual pathway, amygdala-striatal neuronal circuit architecture by which a recent history of chronic stress disrupts the action-outcome learning underlying adaptive agency and promotes the formation of inflexible habits. We found that the basolateral amygdala projection to the dorsomedial striatum is activated by rewarding events to support the action-outcome learning needed for flexible, goal-directed decision making. Chronic stress attenuates this to disrupt action-outcome learning and, therefore, agency. Conversely, the central amygdala projection to the dorsomedial striatum mediates habit formation. Following stress this pathway is progressively recruited to learning to promote the premature formation of inflexible habits. Thus, stress exerts opposing effects on two amygdala-striatal pathways to disrupt agency and promote habit. These data provide neuronal circuit insights into how chronic stress shapes learning and decision making, and help understand how stress can lead to the disrupted decision making and pathological habits that characterize substance use disorders and mental health conditions.

neuroscience↗

bioRxiv2023

A novel human fetal lung-derived alveolar organoid model reveals mechanisms of surfactant protein C maturation relevant to interstitial lung disease

Alveolar type 2 (AT2) cells maintain lung health by acting as stem cells and producing pulmonary surfactant1-3. AT2 dysfunction underlies many lung diseases including interstitial lung disease (ILD), in which some inherited forms result from mislocalisation of surfactant protein C (SFTPC) variants4,5. Disease modelling and dissection of mechanisms remains challenging due to complexities in deriving and maintaining AT2 cells ex vivo. Here, we describe the development of expandable adult AT2-like organoids derived from human fetal lung which are phenotypically stable, can differentiate into AT1-like cells and are genetically manipulable. We use these organoids to test key effectors of SFTPC maturation identified in a forward genetic screen including the E3 ligase ITCH, demonstrating that their depletion phenocopies the pathological SFTPC redistribution seen for the SFTPC-I73T variant. In summary, we demonstrate the development of a novel alveolar organoid model and use it to identify effectors of SFTPC maturation necessary for AT2 health.

cell biology↗