Biology subjects

Li, Y.

Publications and source records attributed to Li, Y..

At least 127 records · Page 7Linked to original sources

bioRxiv2026

RPDynaFlow: Generating RNA-Protein Conformational Ensembles by Atomic Conditional Flow Matching

Conformation ensembles of biomolecules provide the basis for understanding structural transformations and drug design. Deep-learning generative models have advanced protein and small molecule ensemble generation, while RNA-Protein complexes remain unaddressed due to the chemical heterogeneity, limited dataset size and the different flexibility scales of RNA and protein components. We present RPDynaFlow, a flow-matching model to generate conformation ensembles of RNA-protein complexes, trained on 600 ns trajectories of molecular dynamics(MD) simulation. The results show our model extends the sampling range of the phase space compared to MD simulation, which couldbe treated as a rapid and efficient complement to MD trajectoriesfor studying RNA-protein interactions.

biophysics↗

bioRxiv2026

Spatial multi-omics analysis reveals vimentin-high macrophages-endothelial cells niche shapes CAFs heterogeneity in colorectal cancer metastasis

The spatial architecture of the tumor microenvironment (TME) is pivotal in the progression of colorectal cancer (CRC) liver metastasis. By applying high-plex spatial multi-omic mapping and neighborhood analysis to a discovery cohort of colorectal cancer primary tumor (PT) and paired liver metastases (LM), we identified a specialized vimentin-high macrophages-endothelial cells niche that orchestrates cancer-associated fibroblast (CAF) phenotypes. Mechanistically, in primary tumors, vimentin-high macrophages secrete INHBA to activate the ACVR2/TGF-{beta} axis in endothelial cells, driving CAFs toward a myCAF phenotype. Conversely, in liver metastases, these macrophages secrete CXCL9 to trigger the PI3K-Akt/NF-[kcy]B/CXCL12 cascade in endothelial cells, directing CAFs toward an iCAF state. Clinically, high niche activity predicts poor survival. Divergent endothelial signaling in primary versus metastatic lesions exposes site-specific stromal vulnerabilities for therapeutic targeting, with architectural features discernible from routine histopathology. These findings reveal a site-specific regulatory mechanism of the macrophage-endothelial niche, offering a novel and clinically significant biomarker for CRC prognosis.

cancer biology↗

bioRxiv2026

Peripheral Monocyte-Derived Extracellular Vesicles Establish an Immune-Brain Communication Pathway in Alzheimer's Disease

Alzheimer's disease (AD) is increasingly recognized as a systemic disorder involving both central and peripheral immune dysfunction, yet the mechanisms by which peripheral immune cells influence neurodegeneration remain poorly understood. Here we identify a physiological extracellular vesicle (EV)-mediated route through which peripheral monocytes communicate with neurons and show that AD-associated monocyte remodeling converts this pathway into a mechanism that mediates neuronal injury. Reanalysis of single-cell transcriptomic data revealed pronounced inflammatory and EV-related transcriptional remodeling in circulating monocytes from patients with AD. Using a genetic CD63-based EV tracking mouse, we found that EVs released from peripheral Lyz2-expressing myeloid cells, including monocytes, accessed the healthy brain parenchyma and preferentially associated with neurons. EVs isolated from primary peripheral monocytes of 5xFAD mice were enriched in inflammatory cargo, including IL-1{beta}, and markedly suppressed distal axonal growth. Neutralization of EV-associated IL-1{beta} partially restored axonal growth, identifying IL-1{beta} as an important mediator of EV-induced neuronal injury. A{beta} stimulation reproduced key features of this pathogenic EV phenotype in RAW 264.7 macrophage-like cells and induced coordinated metabolic dysfunction and pro-inflammatory activation in primary peripheral monocytes. Moreover, repeated systemic administration of EVs from A{beta}-stimulated RAW 264.7 cells accelerated behavioral and cognitive decline and reduced hippocampal synaptic integrity in 5xFAD mice without increasing cerebral amyloid plaque burden. Together, these findings reveal a peripheral monocyte-EV-neuron communication axis that operates under homeostatic conditions and can be redirected toward pathogenic signaling in AD. Targeting this EV-mediated pathway may provide a therapeutic strategy complementary to current A{beta}-directed approaches.

neuroscience↗

bioRxiv2026

Visualizing zinc-starved slow-replicating Mycobacterium tuberculosis in neutrophil-rich lung lesions

The months-long treatment for tuberculosis is partially attributed to a minor Mycobacterium tuberculosis (Mtb) subpopulation exhibiting phenotypic drug resistance, although origins of these bacilli in hosts remain unknown. Previously, we observed that mycobacteria respond to growth-restrictive limitations of zinc by accumulating Mrf, and inducing Mpy recruitment to the decoding center of the ribosome, thereby hibernating the ribosome in an inactive state. Mrf accumulation - regulated at both transcriptional and post-translational levels by Zur and Clp, respectively, in a zinc-dependent manner - facilitates the formation of stable Mpy-70S ribosome complex in zinc-starved cells. Here, using a translational fusion of Mrf with a fluorescent-reporter protein we visualized zinc-starved mycobacteria with a physiology conducive for Mpy-dependent ribosome hibernation. About half of zinc-starved mycobacterial population expressed microscopically detectable levels of the reporter and exhibited Mpy-dependent slowdown of growth and isoniazid tolerance in vitro. In chronic, high-burden mouse lung infections, ~3% of Mtb bacilli expressed the reporter, and the frequency increased to ~35% upon isoniazid treatment. Transcriptomics of mouse lungs suggests an important role of S100A8/A9 and ZIP2 in neutrophils in zinc mobilization during Mtb infections. Moreover, depletion of neutrophils, or loss of S100A9 caused significant attenuation of zinc starvation response in Mtb. Altogether, the study offers a new approach for visualizing and manipulating slow-replicating Mtb in host tissues.

microbiology↗

bioRxiv2026

Spatial profiling of pooled mRNA-LNP delivery in vivo with NanoSTAMP

Existing pooled lipid nanoparticle (LNP) screens lack spatial information on formulation localization, cellular uptake, and associated multicellular tissue responses. Here we introduce NanoSTAMP, a spatially resolved, pooled in vivo screening platform for barcoded LNP libraries that uses fluorescence in situ hybridization (FISH)-based barcode readout and is compatible with spatial omics. NanoSTAMP links LNP formulation to cell-type specific uptake, cargo expression, and nearby multicellular neighborhoods within intact tissue, which enables spatially-informed design of RNA delivery, establishing tissue architecture as a dimension of LNP performance.

bioengineering↗

bioRxiv2026

A multimodal representation learning platform for accurate molecular ADMET prediction

Accurate ADMET prediction is essential for prioritizing compounds before costly experimental validation, yet ADMET tasks are highly heterogeneous. Properties such as solubility, permeability, protein binding, clearance, transporter activity and toxicity are governed by different molecular signals, ranging from local functional groups and physicochemical descriptors to bonded topology and three-dimensional geometry. Consequently, a single molecular representation or backbone is unlikely to be optimal across all ADMET tasks. We present Trimole-Hybrid, a task-wise multimodal framework that addresses ADMET heterogeneity by selecting or combining predictors built from complementary molecular representations. Trimole-Hybrid constructs a candidate pool of SMILES-, graph-, geometry-sensitive EPT/3D- and chemical descriptor-based predictors. For each task, Trimole-Hybrid selects the best-performing predictor to obtain the final prediction. On 22 Therapeutics Data Commons ADMET benchmarks, Trimole-Hybrid exceeded the public TDC top-1 methods on 10 tasks and ranked within the top 10 for 21 tasks. Ablation studies confirmed the contribution of both complementary multimodal molecular representations and task-specific ensemble strategies. In two small-molecule case studies, Trimole-Hybrid shows sensitivity to changes in essential functional motifs, suggesting its ability to capture ADMET-relevant molecular substructures.

bioinformatics↗

bioRxiv2026

A pharmacokinetics-informed ODE extrapolates long-term fenofibrate transcriptomic responses

Long-term in vivo transcriptomic time courses are costly, limiting assessment of chronic molecular responses from short studies. We developed a pharmacokinetics-informed transcriptomic ordinary differential equation model (PKT-ODE) that links an oral pharmacokinetic profile and Hill drug-effect function to first-order turnover of co-expression modules. The model was fitted to rat liver responses to fenofibrate at three doses in Open TG-GATEs through day 8. At the held-out day-29 endpoint, PKT-ODE achieved Pearson r = 0.960 and mean squared error (MSE) = 0.148. In this dataset, these values achieved lower prediction error and higher correlation than four statistical baselines and validation-selected linear and multilayer-perceptron transition models. Literature-curated peroxisome proliferator-activated receptor target genes occurred only in modules with positive fitted drug effects. These results provide a proof of concept for pharmacokinetics-informed transcriptomic extrapolation; cross-compound, cross-organ and alternative-regimen performance remain to be tested.

systems biology↗

bioRxiv2026

Bridging Morphology and Genomics: A rapid image-based assessment of genomic admixture in the endangered gayal (Bos frontalis)

Abstract The gayal (Bos frontalis) is an endangered semi-domesticated bovine species renowned for its high-quality beef. However, its semi-feral lifestyle, ongoing habitat fragmentation, and extensive genetic introgression from sympatric local cattle have led to dramatic population decline and severe erosion of purebred genetic integrity, posing substantial challenges to its conservation and utilization. To address the urgent demand for rapid, non-invasive, and field-compatible germplasm identification, we developed an integrated artificial intelligence (AI) framework that predicts genomic admixture composition from external morphological images. We constructed a comprehensive dataset comprising 6,245 morphological images and matched genomic sequences from 52 gayals maintained at the Yunnan Provincial Gayal Conservation Farms. Following a preliminary evaluation of nine deep learning models, five were incorporated into a anatomical segment-based multi-modal pipeline, among which Inception_V3 delivered the optimal overall performance. To enhance simultaneous extraction of local fine-grained features and global structural information, we further designed an innovative HybridInceptionViT model by integrating the multi-scale Inception module with the Vision Transformer (ViT) framework. This hybrid model significantly outperformed the baseline Inception_V3, boosting the accuracy of phenotype-derived prediction against genomic admixture estimate from 69.69% to 87.87% (absolute error <15%). This study establishes a practical, low-cost "phenotype-to-genotype" tool for rapid on-site gayal germplasm screening, offering a scalable strategy for the conservation and breeding management of endangered livestock, and holds broad application prospects for agricultural and livestock production systems.

zoology↗

bioRxiv2026

K2P Channels Regulate Presynaptic Organisation through a Membrane Potential-Independent Mechanism

Neuronal ion channels have well-established effects on synaptic plasticity, in many cases by influencing pathways that depend on membrane excitability. Here we find that a C. elegans two-pore domain potassium (K2P) channel, TWK-40, regulates presynaptic organisation through a membrane potential-independent mechanism. Instead, this mechanism depends on TWK-40's effects on intracellular potassium levels. Loss-of-function mutations in TWK-40 lead to excessive presynaptic protein accumulation, while gain-of-function mutations lead to depleted presynaptic components and cause synaptic transmission deficits. These abnormalities are phenocopied by transporter mutations that mimic TWK-40's effects on intracellular potassium concentration, but not by sodium channel mutations that mimic its effects on membrane excitability. This indicates that cytoplasmic potassium promotes presynaptic assembly. This process depends on the PYK-1 pyruvate kinase, a potassium-sensitive enzyme, and three transcription factors. These findings establish a new pathway linking neuronal potassium homeostasis to the control of presynaptic organisation and synaptic function.

molecular biology↗

bioRxiv2026

Single-cell and spatial transcriptomics resolve airway obliteration in bronchiolitis obliterans syndrome

Background: Chronic lung allograft dysfunction (CLAD) is the leading cause of death beyond the first year after lung transplantation, and its most frequent phenotype is bronchiolitis obliterans syndrome (BOS), a fibrotic small-airway disease. Mechanistic work has focused on the immune compartment, yet intensified immunosuppression does not alter established disease. Aim: To resolve which structural cell states populate the BOS graft and how they are spatially organized during airway obliteration. Methods: We profiled explanted lungs from 33 BOS patients undergoing re-transplantation and 33 controls, combining single-nucleus RNA sequencing (14 BOS, 13 controls) with targeted spatial transcriptomics of 108 regions (27 BOS, 24 controls) and multiplex immunofluorescence validation. Single-nucleus data were integrated with a published restrictive allograft syndrome (RAS) atlas. Results: Across 175,128 nuclei and 1.67 million spatially resolved cells, BOS lungs harbored a profibrotic circuit of Aberrant Basaloid cells and CTHRC1+ fibrotic fibroblasts previously described in fibrotic lung diseases, including RAS. Spatial mapping identified a CXCL14+TNC+ injury-associated basal cell state arising early in the obliterative cascade, identifying basal cells as their major reservoir. CTHRC1+ fibroblasts expanded subepithelially replacing resident peribronchial fibroblasts, alongside a peribronchial vascular shift toward systemic venous endothelium. The circuit extended beyond the airway wall to the alveolar interface, defining two convergent remodeling fronts. Conclusion: BOS engages structural-cell circuits largely shared with RAS and fibrotic lung diseases, but along an airway-centered rather than parenchyma-centered axis. CLAD thus emerges as a spatial rather than cellular spectrum, defined by anatomical distribution more than cell identity. Shared structural programs may therefore be targetable across CLAD phenotypes.

cell biology↗

bioRxiv2026

Melittin intervention induces lncRNA response, mitochondrial dysfunction, and cell proliferation in murine cervical cancer cells

Melittin exhibits antitumor activity in cervical cancer models, yet the long non-coding RNA (lncRNA) response and associated regulatory networks remain poorly understood. Here, strand-specific RNA-seq data from melittin-treated and untreated U14 murine cervical cancer cells were analyzed to characterize melittin-responsive lncRNAs and explore their potential functional associations. A total of 28,162 lncRNAs were identified, including 27,307 known and 855 novel transcripts. Differential expression analysis revealed 404 differentially expressed lncRNAs (DElncRNAs), comprising 191 upregulated and 213 downregulated lncRNAs, w most of which were predicted to localize to the cytoplasm or nucleus. Cis-target analysis identified 52 neighboring mRNAs as putative targets of 46 DElncRNAs. Functional enrichment highlighted mitochondrial electron transfer and redox-related processes, including the mitochondrial electron transfer flavoprotein complex, electron-transferring-flavoprotein dehydrogenase activity, ubiquinone binding, and quinone binding. In parallel, melittin induced mitochondrial membrane depolarization and increased intracellular reactive oxygen species accumulation in U14 cells. Co-expression analysis further identified 138 lncRNAs co-expressed with 161 mRNAs, which were enriched in chromatin remodeling, DNA replication, and DNA repair. EdU incorporation decreased with increasing melittin concentrations, indicating suppression of DNA synthesis and proliferative activity. RT-qPCR analysis confirmed the expression trends of selected DElncRNAs. Collectively, these findings demonstrate extensive remodeling of the lncRNA landscape in melittin-treated U14 cells and suggest that melittin-responsive lncRNA-mRNA networks are associated with mitochondrial redox disruption and impaired DNA synthesis. This study provides a transcriptomic framework for identifying candidate lncRNA-mRNA regulatory axes underlying the antitumor response to melittin.

cancer biology↗

bioRxiv2026

Patterns and environmental drivers of amphibian alpha and beta diversity in the Huangshan Mountains, southern Anhui, China

Understanding the spatial patterns of biodiversity and their environmental determinants is fundamental to ecology and conservation, particularly in mountainous transitional zones where species assemblages can shift rapidly. Amphibians, as highly sensitive organisms, are excellent indicators of environmental change, yet quantitative assessments of their diversity in the Huangshan Mountains-a biodiversity hotspot at the junction of the Palaearctic and Oriental realms in southern Anhui, China-remain limited. We conducted systematic line-transect surveys across 200 grids (5 km x 5 km) during the spring and autumn of 2023 and 2024, recording a total of 10,342 individuals belonging to 23 species, 20 genera, 9 families, and 2 orders. Three species (Fejervarya multistriata, Microhyla fissipes, and Bufo gargarizans) were identified as dominant, and two nationally protected species (Hoplobatrachus chinensis and Andrias davidianus) were detected. Inter-annual alpha diversity did not differ significantly, but pronounced seasonal variation was observed, with spring supporting higher Shannon-Wiener and Pielou evenness than autumn in both years. Using generalized additive models and model averaging, we found that annual precipitation and the normalized difference vegetation index (NDVI) were consistently the strongest positive predictors of Shannon-Wiener diversity, Simpson dominance, and species richness, while species richness also declined significantly with increasing human footprint. Total beta diversity (Soerensen dissimilarity) was very high (0.981) and overwhelmingly driven by species turnover (97.86%) rather than nestedness. Partial Mantel tests and distance-based redundancy analysis further revealed that environmental distances-particularly annual precipitation-significantly shaped overall beta diversity and its turnover component after accounting for geographic distance. These results highlight the predominant role of climatic and vegetation gradients in structuring amphibian assemblages in this subtropical mountainous region, providing baseline data to inform local conservation strategies.

ecology↗

bioRxiv2026

Context-dependent variant interpretation from Mendelian disease to genetic predisposition: a proof-of-concept using LPL

As genomic sequencing evolves beyond rare disease diagnostics toward population screening and precision medicine, clinical variant interpretation is increasingly challenged by variants whose clinical consequences depend on biological context. Current frameworks, including the ACMG/AMP guidelines, generally assign a single classification to each variant regardless of inheritance state or genetic context, potentially failing to communicate context-dependent clinical consequences. Here, we address this issue using loss-of-function variants in LPL as a uniquely informative model system in which residual physiological LPL activity can be directly quantified in vivo. By systematically integrating published biallelic LPL genotypes, physiological measurements, functional studies, and clinical phenotypes, we identified a biologically meaningful transition at approximately 10% residual physiological LPL activity. Activity below this level was predominantly associated with classical childhood-onset familial chylomicronemia syndrome (FCS), whereas higher activity was associated with phenotypic attenuation and modifier-dependent clinical expression. Furthermore, heterozygous loss-of-function variants exhibited an estimated penetrance of 5-7% for severe hypertriglyceridemia. We therefore propose a context-dependent framework in which biallelic complete- or near-complete loss-of-function genotypes are interpreted as causative for FCS, whereas heterozygous variants are interpreted as predisposing to severe hypertriglyceridemia while retaining recognition of FCS carrier status. Together, our findings demonstrate that clinical variant interpretation should integrate available biological context--including, where relevant, allelic configuration, residual biological function, and penetrance--rather than rely on the intrinsic molecular consequence of the variant alone. More broadly, this framework provides a conceptual model for interpreting variants across the continuum from Mendelian disease to genetic predisposition in the era of precision medicine.

genetics↗

bioRxiv2026

Chemically programmed multistage morphogenesis in coacervate microdroplets

Chemical reaction-driven morphogenesis enables adaptive membraneless organelles to translate biochemical inputs into coordinated structural and functional responses autonomously, but achieving non-equilibrium morphogenesis in synthetic coacervates remains challenging. Here we report an oxidation programmed multistage morphogenesis in coacervate microdroplets composed of polyethyleneimine (PEI) and sodium thioctate (ST). Coacervate microdroplets form through electrostatic complexation between PEI and ST, together with hydrophobic association among the dithiolane motifs of ST. Hydrogen peroxide converts these dithiolane motifs into more polar species, progressively weakening hydrophobic clustering, increasing hydration within the coacervate phase, and driving the microdroplets away from their initial equilibrium state. This reaction-induced compositional imbalance drives initially homogeneous microdroplets to evolve into multivacuolated intermediates, hollow structures, and finally contracted microdroplets. Experimental and simulation results support a reaction-induced secondary phase separation in which ST oxidation promotes secondary phase separation, osmotic water uptake, vacuole growth, coalescence, and shell remodeling. By recruiting glucose oxidase (GOx) into the coacervate phase to generate H2O2 in situ, we further establish an enzyme-driven route in which glucose autonomously actuates a similar sequence of multistage morphogenesis. Coupling the GOx/glucose pathway with the horseradish peroxidase/Amplex Red cascade reaction further linked glucose-triggered morphogenesis to fluorescent signal generation, enabling coacervate microdroplets to integrate biochemical sensing, structural remodeling, and optical readout. Overall, this work establishes a reaction-induced secondary phase separation for programming life-like multistage morphogenesis in membraneless microcompartments.

biochemistry↗

bioRxiv2026

Spatial cholesterol homeostasis gatekeeps T-cell development and activation by orchestrating signaling and fitness

Cholesterol is essential for T-cell immunity, and its spatial distribution is tightly regulated. Although cholesterol is synthesized in the endoplasmic reticulum (ER), it is predominantly transported to the plasma membrane (PM); however, the machinery mediating this anterograde transport in T cells remains unknown. Here, through a functional genetic screen, we identify oxysterol-binding protein (OSBP) as the principal mediator of ER-to-PM cholesterol transport in T cells. OSBP deficiency depletes accessible PM cholesterol while causing cholesterol accumulation in the ER, resulting in impaired T-cell receptor (TCR) signaling and disruption of ER homeostasis. Using stage-specific conditional knockout mice, we demonstrate that OSBP is required at multiple developmental checkpoints in the thymus, including {beta}-selection, positive selection, and post-selection maturation. Loss of OSBP during early thymocyte development causes a near-complete block in T-cell development, resulting in a profound absence of mature peripheral T cells. In mature T cells, activation markedly increases dependence on OSBP-mediated cholesterol transport, with its inhibition causing ER perturbation and extensive cell death. Finally, we show that disease-associated oxysterols disrupt OSBP-mediated cholesterol transport, leading to T-cell dysfunction and providing a mechanistic explanation for impaired T-cell immunity in pathological settings. Together, our findings identify OSBP as a central regulator of intracellular cholesterol transport that couples membrane cholesterol homeostasis to TCR signaling and ER integrity. These results establish the spatial distribution of cholesterol, rather than its abundance alone, as a fundamental metabolic determinant of thymocyte development and peripheral T-cell function.

immunology↗

bioRxiv2026

An AI System for Autonomous Algorithm Evolution in Drug Development

Artificial intelligence (AI) is increasingly permeating the drug development pipeline. Numerous algorithms for accelerating this multi-stage and multi-task process have been constructed, which depends heavily on expert design and labor-intensive task-specific optimization. Given that AI-driven acceleration of drug development is recognized as a cumulative, often synergistic, effect across multiple stages, the autonomous evolution of existing algorithms across the entire pipeline is demanded to achieve a holistic advancement. Here, we present DrugEvolve, a multi-role large language model system for systematic and autonomous algorithm evolution in drug development. DrugEvolve realizes a closed-loop evolution process by incorporating Researcher, Engineer, and Analyst domains, and enables an iterative design, implementation, evaluation, and refinement of algorithm by leveraging scientific knowledge and accumulated evolutionary experience. Across eleven representative tasks spanning target identification, drug discovery, preclinical study, and clinical trial, DrugEvolve autonomously evolved the corresponding task-specific algorithms and achieved substantial performance enhancement on 120 benchmark test sets. Moreover, it showed robust generalizabilities across heterogeneous data modalities (ranging from biological sequence and graph to molecular topology and textual language), and realized gains in both predictive and generative tasks. Collectively, this AI system can serve not only as an algorithmic infrastructure for drug development, but also as a transferable paradigm for broader scientific domains.

pharmacology and toxicology↗

bioRxiv2026

Listening with your heart: The heartbeat shapes auditory object formation by suppressing the early neural response to sound

Interoceptive sensations, arising from the body's visceral organs such as the heart, are known to impact exteroceptive sensory perception. The classical explanation for heart-to-brain influence, the Baroreceptor Hypothesis, posits that baroreceptors firing during the systolic blood pressure peaks that follow each heartbeat suppress the magnitude of neural responses to exteroceptive sensations. More recent work, however, has demonstrated qualitative (rather than merely magnitude) differences in perception as a function of the cardiac cycle; since it is not obvious how the Baroreceptor Hypothesis could explain these findings, even in principle, they have often been characterized as incompatible. We propose baroreceptor-related suppression of early sensorineural responses need not manifest simply as suppression of corresponding conscious percepts. In a validated computational model of auditory cortex that segregates an ambiguous tone sequence into either one or two auditory objects or "streams," we found suppression of the neural response to one tone type increases the likelihood that tone is parsed into a distinct stream. We subsequently verified this prediction empirically: when presenting such ambiguous sequences to human participants in a manner such that one tone type only occurs during cardiac systole, the initial neural response to that tone -- indexed by the electroencephalographic (EEG) frequency-following response (FFR) -- is indeed suppressed, while participants report hearing the sequence as two separate sounds streams more frequently. Thus, suppression of early sensorineural responses can be sufficient to explain qualitative, not just magnitude, differences in perception when considered in the context of larger neural circuits.

neuroscience↗

bioRxiv2026

Ionizable Lipids Promote Curvature Remodeling and Altered Fluctuation Dynamics in Endosomal Membranes

Inefficient endosomal escape is a crucial barrier to intracellular delivery of nucleic acid therapeutics using lipid nanoparticles (LNPs). The use of ionizable lipids (ILs) has significantly improved cargo delivery efficiency, yet the physical basis of their interaction with endosomal membranes and their role in endosomal escape remain unclear. It has been suggested that, as ILs become cationic during endosomal acidification, electrostatic affinity promotes fusion of the LNPs with the endosome. In this paper, we propose an additional mechanism in which ILs are redistributed from LNPs to host membranes, modulating the elastic properties and curvature of the membrane, lowering the energetic threshold for endosome disruption. To test this, we quantified the spontaneous curvature of clinically relevant ILs and ATP-binding lipids and measured the membrane mechanics of giant unilamellar vesicles (GUVs) with an endosome-relevant composition at endosome-relevant pH. Small-angle X-ray scattering (SAXS) measurements reveal that the incorporation of ILs and ATP lipids into endosome-mimetic membranes shifts the spontaneous curvature towards more negative values. Micropipette aspiration experiments indicated a decrease in the apparent area compressibility modulus of membranes doped with ILs and ATP lipids. In addition, membranes showed enhanced fluctuation amplitudes and altered relaxation behavior, consistent with membrane perturbations associated with lipid insertion and pH- or ATP-driven destabilization. Under conditions promoting the partitioning of ILs or ATP-binding lipids, we further observed reduced bending rigidity and increased heterogeneity in membrane tension. Together, these results support a model in which ILs (as well as newly developed ATP-binding lipids) partition into endosomal membranes, softening the membrane and generating local curvature frustration that facilitates endosomal disruption during the natural acidification process. By quantitatively linking lipid composition with changes in membrane elasticity and fluctuation dynamics, this work provides a biophysical framework for understanding how lipid redistribution may contribute to endosomal escape and improve delivery efficiency.

biophysics↗