Biology subjects

Hill, J.

Publications and source records attributed to Hill, J..

At least 19 recordsLinked to original sources

bioRxiv2026

The Fontan EV Score: A Circulating Extracellular Vesicle-Based Risk Stratification Tool for Fontan-Associated Liver Disease

BackgroundFontan-associated liver disease (FALD) is a universal complication of the Fontan palliation characterized by chronic congestion and progressive hepatic fibrosis. Current diagnostics rely on invasive biopsies or non-specific biochemical and imaging biomarkers that fail to capture early fibrogenesis, creating a critical need for non-invasive biomarkers to stratify disease severity. MethodsWe utilized a translational ovine Fontan model (n = 19) to investigate circulating serum extracellular vesicles (sEVs) as reporters of hepatic pathology. Longitudinal serum samples paired with liver elastography were collected, and sEVs were subjected to multi-omic profiling including small RNA sequencing and proteomics. Regularized regression was used to identify transcriptomic predictors, which were integrated with time post-surgery into an ordinal logistic regression framework to construct the Fontan EV Score (FES). Model performance was evaluated on a held-out test cohort and benchmarked against established serological fibrosis indices. To validate the biological relevance of the FES panel, TGF-{beta}-treated human liver organoids were generated and scored miRNA expression was assessed. ResultsThe sEV proteome exhibited robust separation by surgical physiology, while the small RNA cargo was primarily stratified by fibrotic status. Bioinformatic analysis confirmed a high hepatic origin for these transcripts and identified enrichment of inflammatory pathways including Toll-like receptor and Interleukin-17 cascades in fibrotic subjects. The FES, incorporating time post-surgery and eleven small RNA biomarkers, demonstrated high predictive accuracy in the independent testing cohort with an AUC of 0.876 for moderate and 0.963 for severe fibrosis, substantially outperforming APRI (AUC = 0.618) and FIB-4 (AUC = 0.731). In TGF-{beta}-treated human liver organoids, several scoring miRNAs, including miR-125a-5p and miR-193b-5p, were directionally responsive to profibrotic stimulation. ConclusionsCirculating sEVs carry a liver-associated molecular cargo that can be leveraged for the non-invasive prediction of FALD severity. The FES provides a biologically validated scoring system that substantially outperforms existing serological indices and offers a new avenue for early detection and risk stratification of FALD Novelty and SignificanceO_ST_ABSWhat is Known?C_ST_ABSO_LIFontan-associated liver disease (FALD) is a nearly universal consequence of the Fontan circulation, driven by chronic venous hypertension and reduced cardiac output. C_LIO_LICurrent surveillance tools, including transaminases, composite serological indices (APRI, FIB-4), and elastography, have limited sensitivity and specificity for detecting and staging hepatic fibrosis in the Fontan population. C_LIO_LICirculating small extracellular vesicles (sEVs) carry tissue-derived molecular cargo and have shown diagnostic potential in other liver diseases, but their utility in FALD has not been explored. C_LI What New Information Does This Article Contribute?O_LIMulti-omic profiling of circulating sEVs in a translational ovine Fontan model reveals that the small RNA cargo is stratified by fibrotic status and enriched for inflammatory pathways associated with hepatic stellate cell activation. C_LIO_LIThe Fontan EV Score (FES), integrating time post-surgery with eleven circulating small RNA biomarkers, predicts FALD severity with substantially greater accuracy than APRI and FIB-4. C_LIO_LITGF-{beta}-treated human liver organoids confirm that several FES-associated miRNAs are directly responsive to profibrotic stimulation, providing biological validation independent of Fontan hemodynamics. C_LI This study demonstrates that circulating sEVs function as non-invasive reporters of hepatic fibrogenesis in the Fontan circulation and introduces the first EV-based scoring system for FALD risk stratification. The FES achieved an AUC of 0.876 for moderate and 0.963 for severe fibrosis in an independent test cohort, outperforming established serological indices that were originally developed for viral hepatitis but which perform poorly in congestive hepatopathy. By combining molecular biomarker discovery with in vitro functional validation, this work establishes a foundation for developing targeted, non-invasive diagnostics to guide surveillance and clinical decision-making in the growing Fontan patient population.

bioinformatics↗

bioRxiv2026

Untargeted metabolomics reveals host responses and metabolites linked to host compatibility in Rafflesiaceae parasitism

Rafflesiaceae, including Rafflesia, Sapria, and Rhizanthes, are some of the rarest flowering plants in the world, known for producing the largest blooms on Earth. These holoparasites depend exclusively on Tetrastigma (Vitaceae) vines, yet the chemical basis for this host specificity is poorly understood, complicating conservation efforts. Untargeted negative-ion LC- MS metabolomics was used to profile Rafflesiaceae buds and seeds, infected Tetrastigma hosts associated with Rafflesia lagascae, R. speciosa, and Sapria himalayana, uninfected Tetrastigma hosts, and corresponding non-host species from the Philippines and Thailand. Python scripts used for data processing and visualization were developed with generative AI assistance and validated by the authors. Principal component analysis revealed distinct metabolomic profiles across samples, with significant shifts in host metabolites upon infection. Infected Tetrastigma tissues showed nominal enrichment in phenylpropanoid and gibberellin-related metabolites, suggestive of defense and hormonal pathway activation during Rafflesia infection, as well as citric acid, suggesting increased energy demand to support the parasite. Non-host Tetrastigma species showed nominal enrichment in metabolites putatively annotated as stilbenoids, resveratrol diglucosides, and condensed tannins such as procyanidin B2, compounds broadly associated with plant defense. Rafflesia seeds harbored fatty acids/oxylipins, while Rafflesia buds accumulated gallic acid derivatives, compounds also reported in galls. These findings support a chemically mediated model of host compatibility and parasitism, with implications for the ex-situ conservation of these endangered plants.

plant biology↗

bioRxiv2026

Leveraging Homologous Recombination Deficiency via the Repositioned Prodrug CB1954

AO_SCPLOWBSTRACTC_SCPLOWHomologous recombination deficiency (HRD) is an actionable vulnerability found in a substantial fraction of human cancers, yet current HRD-directed therapies are limited by toxicity, incomplete responses, and acquired resistance. Many DNA-damaging agents were developed before DNA repair biomarkers were available, suggesting that abandoned agents may harbor previously unrecognized genotype-selective activity. Here, through a focused screen of DNA-damaging agents in isogenic homologous recombination-proficient and -deficient models, we identify CB1954, a decades-old nitrobenzamide aziridine prodrug, as highly selective for BRCA2-deficient tumor cells. CB1954 forms DNA interstrand crosslinks independent of HR status, but selectively induces DNA-damage signaling, apoptosis, and loss of clonogenic survival in HR-deficient cells. Targeted DDR CRISPR screening and isogenic validation define a distinct repair dependency for the Fanconi anemia and homologous recombination pathways, with limited dependence on mismatch repair or nucleotide excision repair. Genetic and pharmacologic perturbation of NQO2, the bioactivating enzyme for CB1954, reveals a bifurcated mechanism in which NQO2-dependent activation selectively contributes to HRD cytotoxicity, while aziridine-dependent lesions likely account for residual activity in HR-proficient cells. CB1954 exhibits favorable preclinical pharmacokinetic properties and genotype-dependent antitumor activity in BRCA2-deficient xenografts. These findings reposition CB1954 as a historically overlooked HRD-selective agent and demonstrate that biomarker-guided profiling of DNA-damaging agents can uncover new opportunities for precision oncology.

cancer biology↗

bioRxiv2026

Brain morphological pattern is associated with the presence, severity, and transition of transdiagnostic psychiatric disorders in preadolescents

Cognitive function, psychological processes, mental states, and behaviors are key dimensions of human subjective experience that separately relate to mental disorders across diagnostic categories. However, whether these dimensions are linked to common or distinct brain morphological patterns that convey risk or resilience for psychiatric disorders remains unclear. The current study is a longitudinal investigation on 11,875 youths from the Adolescent Brain Cognitive Development (ABCD) Study aged 9-10 years at baseline. A machine learning approach based on canonical correlation analysis was used to identify latent dimensional associations of cortical morphology (4 metrics: surface area, cortical and subcortical volume, cortical thickness, and sulcal/gyral depth) with multidomain behavioral assessments including cognitive scores and psychological measures indexing motivation, impulse control, mental states, and behaviors across a normative continuum from healthy to pathological. Across morphological measures, we identified a robust latent brain structural variate that correlated positively with cognitive performance and negatively with psychological measures indexing greater psychology. Notably, higher scores on this brain variate reflected larger cortical surface area and cortical volume--especially in the temporal gyri--together with a posterior-anterior gradient in cortical thickness, showing relatively greater thickness in occipital, parietal, and temporal cortices and lower thickness in cingulate and frontal regions. This brain variate and the related cognitive-psychological-behavioral variate remained stable at the 2-year follow-up, demonstrating temporal consistency. Importantly, the brain variate showed a dose-dependent relationship with the cumulative number of psychiatric diagnoses assessed concurrently and at 2-year follow-up, with lower brain variate scores being associated with higher numbers of comorbid diagnoses. In addition, the brain scores were associated with longitudinal transitions between healthy and diagnosed states over the 2-year study period, in which lower scores at baseline were associated with persistent psychiatric diagnoses whereas higher scores at baseline were associated with persistent healthy states, suggesting that the brain scores capture a vulnerability- resilience continuum for psychopathology. By revealing shared brain structural substrates across conventional diagnostic boundaries, these findings advance the neurodevelopmental understanding of psychiatric disorders and highlight the potential utility of morphology-informed approaches for early screening and intervention in youth.

developmental biology↗

bioRxiv2025

From rest to focus: Pharmacological modulation of the relationship between resting state dynamics and task-based brain activation

Dynamic resting-state brain activity provides insight into intrinsic neural function and holds promise for predicting individual responses to cognitive demands and pharmacological interventions. This research could ultimately guide medication selection, yet links between network dynamics and medication effects on cognitive function require further validation. Here, we examined whether dynamic activity of an attentional network at rest relates to task-evoked brain activation on the Multi Source Interference Task (MSIT) following administration of methylphenidate (20mg) and haloperidol (2mg), which have opposing effects on attention and catecholaminergic function. Fifty-nine healthy adults completed resting-state and task-based fMRI on three separate days on which they received methylphenidate, haloperidol, or placebo in a double-blind placebo-controlled design. Coactivation pattern analysis determined time spent in the dorsal attention network (DAN) under placebo at rest. Linear mixed-effects modelling assessing the relationship between MSIT task activation under drug and time spent in DAN at rest under placebo and MSIT task activation under drug identified a significant interaction in the dorsolateral prefrontal cortex (dlPFC; p<0.001). Post-hoc analyses indicated that more time in the DAN at rest under placebo was associated with decreased MSIT dlPFC activation under methylphenidate and increased dlPFC activation under haloperidol. Findings demonstrate that resting dynamics of an attentional network are linked to task-related brain responses under different drug conditions within a region implicated in attentional control and sensitive to catecholaminergic variance. Resting-state dynamics may predict pharmacological modulation of goal-directed cognition, highlighting the potential clinical utility of resting-state dynamics in predicting medication response and supporting individualized treatment.

neuroscience↗

bioRxiv2025

Maturation of Dorsal Association Tracts during Preadolescence Links to Concurrent and Future Cognitive Performance and Transdiagnostic Psychopathology

Many psychiatric disorders begin during adolescence, coinciding with the rapid development of brain white matter (WM). However, it remains unclear whether deviations from normal WM maturation during this age period contribute to the development of psychopathology. In this study, we developed and validated normative models of brain age based on specific WM tracts using three large-scale developmental datasets (a total of [~]10,000 subjects). We found that tract-specific deviations in WM development of association and limbic/subcortical systems were linked to concurrent cognition and psychopathology. The spatial pattern of the association system aligned closely with distributions of high-order brain networks, and with mitochondrial content and respiratory capacity. The maturation of the association system contributed significantly to better cognitive performance assessed two or three years later. Importantly, delayed WM development especially in dorsal association tracts predicted psychiatric disorders across diagnoses and disorder onset over a 2-year follow-up. By identifying tract-specific WM development during preadolescence as a predictor of cognitive capacity and psychiatric disorder risks, this study provides a valuable framework for tracking individualized brain maturation and understanding the neurobiological underpinnings of cognitive performance and transdiagnostic psychopathology.

neuroscience↗

bioRxiv2025

Sustainable Memristors from Shiitake Mycelium for High-Frequency Bioelectronics

Neuromorphic computing, inspired by the structure of the brain, offers advantages in parallel processing, memory storage, and energy efficiency. However, current semiconductor-based neuromorphic chips require rare-earth materials and costly fabrication processes, whereas neural organoids need complex bioreactor maintenance. This study explores shiitake (Lentinula edodes) fungi as a robust, sustainable alternative, exploiting its adaptive electrical signaling, which is akin to neuronal spiking. We demonstrate fungal computing via mycelial networks interfaced with electrodes, showing that fungal memristors can be grown, trained, and preserved through dehydration, retaining functionality at frequencies up to 6 kHz. Notably, shiitake has exhibited radiation resistance, suggesting its viability for aerospace applications. Our findings show that fungal computers can provide scalable, eco-friendly platforms for neuromorphic tasks, bridging bioelectronics and unconventional computing.

bioengineering↗

bioRxiv2025

Comparative regulomics provides novel insight into the evolution of wood formation across dicot and conifer trees

Understanding the regulatory program underlying wood formation is key to improving biomass production and carbon sequestration in trees. However, how wood formation evolved and how these programs have been rewired across lineages remains unclear. Here, we present the first high-spatial-resolution evo-devo resource spanning the wood transcriptomes of six tree species - three dicots and three conifers - capturing 250 million years of evolutionary divergence. Using orthology-aware co-expression network analysis, we identified genes with conserved and lineage-specific expression patterns. By integrating chromatin accessibility data and transcription factor motif analysis, we further inferred regulatory networks for xylem differentiation and secondary cell wall formation. We demonstrate how this dataset can be used to answer long standing questions in wood biology related to differences in acetylation of cell wall polymers and master regulators of xylem specification across dicot and conifer tree species. The data offer a foundational resource for the tree biology and evo-devo communities, and are publicly available at PlantGenIE.org.

genomics↗

bioRxiv2025

RAS pathway activation drives clonal selection and monocytic differentiation in FLT3 and BCL2 inhibitor resistance

Despite efficacy of FLT3 and BCL2 inhibition in acute myeloid leukemia (AML), relapse limits survival. Mutation status and AML monocytic differentiation are implicated in resistance. On-treatment tumor evolution may select for genetically distinct clones or shifts in differentiation not resolvable by bulk sequencing. We performed multiomic single cell (SC) DNA/protein and RNA/protein profiling of patients treated on a clinical trial of the BCL2 inhibitor venetoclax and the FLT3 inhibitor gilteritinib (Ven/Git) to characterize immunophenotypic, transcriptional, and genetic clonal evolution on therapy. We found that while Ven/Gilt effectively eliminated FLT3 mutant clones, it selected for RAS mutations, RAS pathway activation and RAS-associated monocytic differentiation. In an in vitro model of monocytic differentiation associated with heightened RAS pathway activation, we demonstrated that MEK inhibition re-sensitized to Ven/Gilt. These data indicate RAS signaling is central to FLT3 and BCL2 inhibitor resistance, is tightly coupled to monocytic differentiation and can be overcome by RAS pathway inhibition. COIC.C.S. has provided educational talks for Astellas Pharma, served on advisory boards for Genentech/Abbvie and received research funding from Abbvie. B.C., Y.S. and J.H. are employees of Abbvie. M.S. and H.H. are or were previously employees of Genentech. FundingThis work was supported in part by Abbvie. C.C.S. is a Leukemia & Lymphoma Society Scholar in Clinical Research and a Damon Runyon-Richard Lumsden Foundation Clinical Investigator supported (in part) by the Damon Runyon Cancer Research Foundation (CI-99-18). Statement of SignificanceMutational and non-mutational RAS signaling activation drives clonal selection, monocytic differentiation and treatment resistance to FLT3 and BCL2 inhibition in AML. MEK inhibition can resensitize resistant AML cells, suggesting therapeutic potential for combined FLT3, BCL2 and RAS pathway inhibition in AML.

cancer biology↗

bioRxiv2025

Hypoxia-related immune subsets induced by Salmonella Typhi infection link early bacterial gut invasion to human infection outcomes

Salmonella Typhi (S. Typhi), the causative agent of typhoid disease, remains a major public health concern. Owing to the human-restricted nature of S. Typhi, current studies of typhoid pathogenesis in animal models are limited to a murine non-typhoidal pathogen. Furthermore, human studies are limited to analyses of peripheral immune responses which are blind to tissue-specific immunity and do not allow perturbations. What is now needed is an integrative approach that will provide mechanistic insights into S. Typhi pathogenesis and immune correlates of infection outcome. Here, we performed an integrated single-cell analysis of immune responses from the human S. Typhi challenge model and mouse model of typhoid disease, to associate biological mechanism with human infection outcome. Most prominent, we revealed immune subsets with a hypoxia-related signature in circulating immune cells from individuals that develop disease in the human challenge model. This signature was also evident in the mouse model in activated macrophages infiltrating into the Peyers patches, but not during infection with a mutant strain impaired for gut invasion. We further identified hypoxia-related signature as a general immune correlate of disease outcome in other infection- and inflammatory-related diseases. Collectively, using integrated analysis of mouse and human infection models, we revealed a hypoxia-related signature that link immune responses during bacterial invasion to increased risk of developing typhoid disease in humans, suggesting a possible causative role during the development of typhoid disease.

immunology↗

bioRxiv2024

Metabolic and Cellular Differences Between Sedentary and Active Individuals at Rest and During Exercise

BackgroundPhysical inactivity is a major contributor to cardiometabolic disease and mortality. Although mitochondrial dysfunction characterizes overt pathology, whether a distinct mitochondrial phenotype is present in apparently healthy sedentary adults remains unclear. MethodsNine sedentary (SED) and ten physically active (AC) healthy males (42 {+/-} 14 yr) were studied. Skeletal muscle bioenergetics were assessed using high-resolution respirometry, fluxomics, metabolomics and protein expression analyses. Whole-body physiology was evaluated using cardiopulmonary exercise testing (CPET) including fat oxidation and blood lactate measurements. ResultsAt rest, SED exhibited marked reductions in mitochondrial capacity, including Complex I (-36%), Complex II (-28%), electron transport system capacity (-34%), and ATP-synthase-coupled respiration (-30%, all p < 0.01). The most pronounced alteration was a 49% reduction in mitochondrial pyruvate carrier (MPC1) expression, which closely correlated with reduced pyruvate oxidation (-37%, p = 0.006) and lower TCA intermediates. SED also showed reduced MCT1 abundance, impaired fatty acid oxidation capacity (-32% to -35%), decreased CPT1 activity (-51%), altered cardiolipin composition and elevated ROS/O flux ratios. During exercise, SED demonstrated lower VO max (-38%), reduced fat oxidation (-35%) and higher blood lactate accumulation (>60%, p < 0.001). Mitochondrial function was strongly associated with exercise performance (r = 0.57-0.78, p < 0.01). ConclusionsHealthy sedentary adults are characterized by reduced mitochondrial function characterized by decreased substrate entry and oxidation, reduced oxidative capacity and diminished metabolic flexibility. CPET-derived fat oxidation and blood lactate responses closely reflect skeletal muscle mitochondrial function, providing non-invasive physiological markers of metabolic health. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/608601v2_fig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1a3a629org.highwire.dtl.DTLVardef@f1ea48org.highwire.dtl.DTLVardef@4c4a96org.highwire.dtl.DTLVardef@b4f879_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Schematic of skeletal muscle mitochondrion: SED side shows reduced MPC, CPT1, L4CL, and TCA flux with elevated ROS; AC side shows robust OXPHOS, fat oxidation, and lactate clearance. Arrows link to CPET as a non-invasive diagnostic tool for mitochondrial health. C_FIG

biochemistry↗

bioRxiv2024

In Silico Treatment: a computational framework for animal model selection and drug assessment

The translation of findings from animal models to human disease is a fundamental part in the field of drug development. However, only a small proportion of promising preclinical results in animals translate to human pathophysiology. This underscores the necessity for novel data analysis strategies to accurately evaluate the most suitable animal model for a specific purpose, ensuring cross-species translatability. To address this need, we present In Silico Treatment (IST), a computational method to assess translation of disease-related molecular expression patterns between animal models and humans. By simulating changes observed in animals onto humans, IST provides a holistic picture of how well animal models recapitulate key aspects of human disease, or how treatments transform pathogenic expression patterns to healthy ones. Furthermore, IST highlights particular genes that influence molecular features of pathogenesis or drug mode of action. We demonstrate the potential of IST with three applications using bulk transcriptomics data. First, we assessed two mouse models for idiopathic pulmonary fibrosis (IPF): one involving injury with intra-tubular Bleomycin exposure, and the other Adeno-associated-virus-induced, TGF{beta}1-mediated tissue transformation (AAV6.2-TGF{beta}1). Both models exhibited gene expression patterns resembling extracellular matrix derangement in human IPF, whereas differences in VEGF-driven vascularization were observed. Second, we confirmed known features of non-alcoholic steatohepatitis (NASH) mouse models, including choline-deficient, l-amino acid-defined diet (CDAA), carbon tetrachloride hepatotoxicity injury (CCl4) and bile duct ligation surgery (BDL). Overall, the three mouse models recapitulated expression changes related to fibrosis in human NASH, whereas model-specific differences were found in lipid metabolism, inflammation, and apoptosis. Third, we reproduced the strong anti-fibrotic signature and induction of the PPAR signaling observed in the Elafibranor experimental treatment for NASH in the CDAA model. We validated the contribution of known disease-related genes to the findings made with IST in the IPF and NASH applications. The complete data integration IST framework, including an interactive app to integrate and compare datasets, is made available as an open-source R package. Author summaryPreclinical testing plays a pivotal role in the drug development process, serving as a crucial evaluation phase before a new drug can be tested on humans in clinical trials. The drug must undergo a rigorous evaluation in in vivo and in vitro preclinical studies to assess its safety and efficacy. However, positive outcomes in preclinical animal models do not always translate to positive results in humans, mainly due to biological differences. Therefore, selecting an animal model that closely mirrors human disease traits and detecting and accounting for model limitations is of paramount importance. Over the last decade, the availability of gene expression data in both animals and humans has substantially increased. Gene expression states and perturbations are routinely employed as a proxy to predict and understand changes in disease states. Here, we developed In Silico Treatment, a computational method designed to overlay the gene expression changes observed in animals onto humans, quantifying the change in human disease status. We applied this method to mouse models for idiopathic pulmonary fibrosis and non-alcoholic steatohepatitis, two severe fibrotic diseases. We successfully identified known features of the disease models and provide a granular gene-level rationale behind our predictions. Consequently, our method shows promise as an effective approach to improve animal model selection and thus clinical translation.

bioinformatics↗

bioRxiv2024

Sex differences in oxycodone-taking behaviors are linked to disruptions in reward-guided, decision-making functions

Problematic opioid use that emerges in a subset of individuals may be due to pre-existing disruptions in the biobehavioral mechanisms that regulate drug use. The identity of these mechanisms is not known, but emerging evidence suggests that suboptimal decision-making that is observable prior to drug use may contribute to the pathology of addiction and, notably, serve as a powerful phenotype for interrogating biologically based differences in opiate-taking behaviors. The current study investigated the relationship between decision-making phenotypes and opioid-taking behaviors in male and female Long Evans rats. Adaptive decision-making processes were assessed using a probabilistic reversal-learning task and oxycodone- (or vehicle, as a control) taking behaviors assessed for 32 days using a saccharin fading procedure that promoted dynamic intake of oxycodone. Tests of motivation, extinction, and reinstatement were also performed. Computational analyses of decision-making and opioid-taking behaviors revealed that attenuated reward-guided decision-making was associated with greater self-administration of oxycodone and addiction-relevant behaviors. Moreover, pre-existing impairments in reward-guided decision-making observed in female rats was associated with greater oxycodone use and addiction-relevant behaviors when compared to males. These results provide new insights into the biobehavioral mechanisms that regulate opiate-taking behaviors and offer a novel phenotypic approach for interrogating sex differences in addiction susceptibility and opioid use disorders.

neuroscience↗

bioRxiv2023

Remyelination protects neurons from DLK-mediated neurodegeneration

Chronic demyelination and oligodendrocyte loss deprive neurons of crucial support. It is the degeneration of neurons and their connections that drives progressive disability in demyelinating disease. However, whether chronic demyelination triggers neurodegeneration and how it may do so remain unclear. We characterize two genetic mouse models of inducible demyelination, one distinguished by effective remyelination and the other by remyelination failure and chronic demyelination. While both demyelinating lines feature axonal damage, mice with blocked remyelination have elevated neuronal apoptosis and altered microglial inflammation, whereas mice with efficient remyelination do not feature neuronal apoptosis and have improved functional recovery. Remyelination incapable mice show increased activation of kinases downstream of dual leucine zipper kinase (DLK) and phosphorylation of c-Jun in neuronal nuclei. Pharmacological inhibition or genetic disruption of DLK block c-Jun phosphorylation and the apoptosis of demyelinated neurons. Together, we demonstrate that remyelination is associated with neuroprotection and identify DLK inhibition as protective strategy for chronically demyelinated neurons. HighlightsO_LICharacterization of a transgenic mouse model of demyelination without subsequent remyelination C_LIO_LIRemyelination protects neurons from axon loss and neuronal apoptosis C_LIO_LIMAPK and c-Jun phosphorylation are increased in mice featuring remyelination failure C_LIO_LIDLK is necessary for the apoptosis of chronically demyelinated neurons C_LI

neuroscience↗

bioRxiv2023

Structural Optimization of siRNA Conjugates for Albumin Binding Achieves Effective MCL1-Targeted Cancer Therapy

The high potential for therapeutic application of siRNAs to silence traditionally undruggable oncogenic drivers remains largely untapped due to the challenges of tumor cell delivery. Here, siRNAs were optimized for in situ binding to albumin through C18 lipid modifications to improve pharmacokinetics and tumor delivery. Systematic variation of siRNA conjugates revealed a lead structure with divalent C18 lipids each linked through three repeats of hexaethylene glycol connected by phosphorothioate bonds. Importantly, we discovered that locating the branch site of the divalent lipid structure proximally (adjacent to the RNA) rather than at a more distal site (after the linker segment) promotes association with albumin, while minimizing self-assembly and lipoprotein association. Comparison to higher albumin affinity (diacid) lipid variants and siRNA directly conjugated to albumin underscored the importance of conjugate hydrophobicity and reversibility of albumin binding for siRNA delivery and bioactivity in tumors. The lead conjugate increased tumor siRNA accumulation 12-fold in orthotopic mouse models of triple negative breast cancer over the parent siRNA. When applied for silencing of the anti-apoptotic oncogene MCL-1, this structure achieved approximately 80% MCL1 silencing in orthotopic breast tumors. Furthermore, application of the lead conjugate structure to target MCL1 yielded better survival outcomes in three independent, orthotopic, triple negative breast cancer models than an MCL1 small molecule inhibitor. These studies provide new structure-function insights on optimally leveraging siRNA-lipid conjugate structures that associate in situ with plasma albumin for molecular-targeted cancer therapy.

bioengineering↗

bioRxiv2022

A whole blood intracellular cytokine assay optimised for field site studies demonstrates polyfunctionality of CD4+ T cells in acute scrub typhus

BackgroundAssessment of cellular immune responses by combining intracellular cytokine staining and immunophenotyping using flow cytometry enables the simultaneous measurement of T cell phenotype and effector function in response to pathogens and vaccines. The use of whole blood samples rather than peripheral blood mononuclear cells avoids both the need for immediate processing and loss of functional antigen presenting cells due to processing and cryopreservation. Using whole blood provides the possibility to stimulate peripheral T cells in situ, and is more suitable for studies where sample volume is limited, such as those involving children, the elderly and critically ill patients. The aim of this study was to provide a robust tool for the assessment of antigen-specific T cell responses in a field site setting with limited resources. Methodology/Principle FindingsWe optimised a flow cytometry-based whole blood intracellular cytokine assay (WBA) with respect to duration of antigen stimulation and intracellular protein retention time. We demonstrate the ability of the WBA to capture polyfunctional T cell responses in the context of acute scrub typhus infection, by measuring IFN-{gamma}, TNF and IL-2 in CD4+ and CD8+ T cells in response to the causative agent O. tsutsugamushi (OT). Using an optimised OT antigen preparation, we demonstrate the presence of polyfunctional antigen-specific memory CD4+ T cells in the blood of scrub typhus patients. Conclusions/SignificanceIn conclusion, this flow cytometry-based WBA is well-suited for use at field study sites, and enables the assessment of polyfunctional T cell responses to infectious agents and vaccines through delineation of antigen-specific cytokine secretion at the single cell level. Author summaryScrub typhus is an acute febrile illness caused by the bite of infected chigger mites transmitting O. tsutsugamushi, a gramnegative obligate intracellular bacteria in the family Rickettsiaceae. The disease progression and clinical manifestations are closely associated with host immune responses. T cell responses are in strong relation with immune protection against scrub typhus. As there is limited knowledge on specific T cell roles against scrub typhus, we optimized a flow-cytometer based protocol to assess O. tsutsugumushi-specific T cell responses in whole blood samples, which is suitable for studies in limited resource settings. This method requires low blood volumes, but enables multiparametric immunophenotyping assessments. The optimized WBA protocol could be a useful tool for comprehensive immunopathological studies in scrub typhus, and other infectious diseases as well as vaccine studies in areas with limited availability of specialized equipment, while reliably capturing the complexity of the immune response.

immunology↗

bioRxiv2022

Single cell transcriptional landscape of long non-coding RNAs orchestrating mouse heart development

Long non-coding RNAs (lncRNAs) comprise the most representative transcriptional units of the mammalian genome, and theyre associated with organ development that can be associated with the emergence of diseases, such as cardiovascular diseases. Thus, we used bioinformatic approaches, machine learning algorithms and statistical techniques to define lncRNAs involved in mammalian cardiac development. We used a single-cell transcriptome dataset generated from 4 embryonic and 4 postnatal stages. Our study identified 8 distinct cell types, novel marker transcripts (coding/lncRNAs) and also, differential expression and functional enrichment analysis reveal cardiomyocyte subpopulations associated with cardiac function; meanwhile modular co-expression analysis reveals cell-specific functional insights for lncRNAs during myocardial development, including a potential association with key genes related to disease and the "fetal gene program". Our results evidence the role of particular lncRNAs in heart development, and highlights the usage of co-expression modular approaches in the cell-type functional definition.

bioinformatics↗

bioRxiv2022

Low mutation load in a supergene underpinning alternative male mating strategies in ruff

Ruffs are shorebirds with an elaborate lekking behavior involving three male morphs with different mating strategies: Independents, Satellites, and Faeders1,2. The latter two are heterozygous for different versions of a supergene maintained by an inversion that were estimated to have occurred about 4 million years ago3. Faeders carry an intact inversion while the Satellite allele is recombinant, both of which are expected to accumulate high mutational load because they are recessive lethals. Here we have constructed a highly contiguous genome assembly of the inversion region for both the Independent and Satellite haplotypes. The recombination event(s) between an inverted and non-inverted chromosome creating the Satellite allele must have occurred recently (within the last 100,000 years) based on the minute sequence divergence between the Satellite and Independent alleles in the recombinant regions. Contrary to expectations4,5, we find no expansion of repeats and only a very modest mutation load on the Satellite allele in the nonrecombinant region despite high sequence divergence (1.46%). The essential centromere protein CENPN gene is disrupted by the inversion, and surprisingly is as well conserved on the inversion haplotypes as on the noninversion haplotype. The results suggest that the inversion may be much younger than previously thought. The lack of mutation load despite recessive lethality can be explained by the introgression of the inversion from a now extinct lineage.

evolutionary biology↗