Biology subjects

Huang, C.

Publications and source records attributed to Huang, C..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

A Modular Toolkit For Theophylline-Dependent Synthetic Auxotrophs Via Riboswitch-Gated Essential Genes

Synthetic auxotrophs are a useful means for developing genetically encoded biocontainment systems. Current methods for developing synthetic auxotrophs are complicated or expensive, limiting access and adoption of biocontainment technologies. To address this gap, we developed a simple and modular platform for creating synthetic auxotrophs based on ligand-dependent translational gating of essential genes. By inserting a theophylline-responsive riboswitch upstream of essential genes in Escherichia coli, we created strains whose viability depends on the presence of theophylline. We systematically applied this approach to 29 essential genes, obtained ligand-dependent growth phenotypes for 19 targets, and found that 18 of these essential genes yielded stringent live-die synthetic auxotrophs. These strains exhibited robust theophylline dependence with escape frequencies ranging from 1 x 10-5 to 1 x 10-6 (most below limit of detection). Our modular design allows for the rapid (<1 week), low-cost, and reliable generation of synthetic auxotrophs. This work introduces ligand-dependent translational control as a new mechanism for engineering synthetic auxotrophy and provides an accessible platform that expands the biocontainment toolkit.

synthetic biology↗

bioRxiv2025

Gut Microbiota-derived Adenosine Determines the Efficacy of Electroconvulsive Therapy for Depression

Electroconvulsive therapy (ECT) is a final procedure for major depressive disorders (MDD). However, the effectiveness of ECT in treating MDD patients varies. Here we identified gut microbiota as a potential restraining factor of ECT efficacy. By using a 5-day electroconvulsive shock (ECS) in depression mouse model of chronic restraint stress (CRS), it was observed that the antidepressant effect of ECS was suppressed after antibiotics (ABX)-induced microbiota dysbiosis, which also resulted in elevated c-Fos expression of CRH neurons in paraventricular nucleus of hypothalamus (PVN) and increased serum corticosterone levels after ECS. Metabolomic analysis revealed the critical involvement of microbiota associated purine metabolism, and the supplement of gut microbiota-derived adenosine was able to recover the antidepressant effect of ECS in ABX-treated CRS mouse model. Based on the neural tracing from colon to brain and the immunofluorescence staining, it was surmised a gut-brain axis originated from Adora1-expressing cells in colon mediate this biological process. Furthermore, adenosine supplement alleviated the further deterioration of post-ECS memory loss and impairment of synaptic plasticity induced by ABX-treatment as well. Our findings suggest a potential role of microbial adenosine metabolism in ECT efficacy determination and side effect protection, highlights potential application of adenosine supplement in antidepressant therapies of those depression patients with microbiota dysbiosis.

systems biology↗

bioRxiv2025

Lrrc55 modulates beta-cell resilience and calcium transporter expression under metabolic and physiologic stress

During pregnancy, pancreatic {beta}-cell mass and function are increased in adaptation to insulin resistance; this requires the action of prolactin receptor signaling. Recently, we discovered the Lrrc55, an auxiliary subunit of the voltage- and calcium-activated potassium channel (BK channel), is a prosurvival factor in {beta}-cell, and its expression and highly and specifically up regulated in the pancreatic islets during pregnancy. We found that overexpression of Lrrc55 protects {beta}-cells from glucolipotoxicity (GLT)-induced apoptosis. The protective effect of Lrrc55 is associated with dampening of the ER stress response and preservation of the releasable pool of calcium in the ER. Thus, we hypothesized that Lrrc55 protects {beta}-cells from GLT-induced ER stress and apoptosis by regulating ER calcium handling. Here, we report that Lrrc55 restored the GLT-mediated decrease in expression levels the insulin regulators, Pdx-1 and MafA, as well as the ER calcium regulator SERCA. Lrrc55 also attenuated the GLT-induced increase in expression of the ER calcium channel RyR2. Lrrc55 also attenuated GLT-mediated increase in protein expression of pro-apoptotic molecules CHOP and IRE1, and increased activation of the anti-apoptotic molecule Akt. However, Lrrc55 does not alter the activity levels of SERCA or IP3R under physiologic conditions. Transgenic mice with global deletion of Lrrc55 (Lrrc55-/-) are more susceptible to streptozotocin-induced diabetes. Surprisingly, Lrrc55-/- mice are more glucose tolerant and secreted more insulin during pregnancy. Together, these results suggest a role for Lrrc55 in maintaining expression of the ER calcium regulators in the presence of GLT but it may negatively regulate insulin secretion.

physiology↗

bioRxiv2025

Structural basis of HSV-1 DNA replication origin-binding protein UL9

The herpesvirus DNA replication machinery comprises a battery of viral enzymes that orchestrate viral genome synthesis. In herpes simplex virus type 1 (HSV-1), the machinery consists of seven essential components, including the origin-binding protein UL9, the single-stranded DNA (ssDNA)-binding protein ICP8, the heterodimeric DNA polymerase complex UL30-UL42, and the heterotrimeric helicase-primase complex UL5-UL8-UL52. UL9, a superfamily 2 (SF2) helicase, functions as a dimer that specifically recognizes replication origins and unwinds duplex DNA to initiate replication. Furthermore, UL9 recruits the replication machinery through interactions with viral components and engages cellular proteins that regulate its function. However, the molecular mechanisms underlying UL9s multifunctionality remain incompletely understood due to the lack of structural information. Here, we present cryo-electron microscopy structures of UL9 in both apo and DNA-bound states. Together with biochemical and enzymatic assays, we elucidate the molecular basis of UL9 dimerization, origin recognition and allosteric regulation by ICP8.

microbiology↗

bioRxiv2025

Simple, Fast and Highly Efficient One-or Two-step Proteomic Preparation Enables Deep Profiling of Microgram-level FF and FFPE Tissues

Large-scale tissue proteomics requires workflows that are efficient, rapid, and repeatable across diverse samples. Herein, we present Simple Workflow for Integrated and Fast Tissue-preparation (SWIFT), which enables complete processing of fresh- frozen (FF) and formalin-fixed, paraffin-embedded (FFPE) tissues in either one- or two-step formats, while maintaining deep proteome coverage with high repeatability from low to microgram-level tissues. For FF tissues, an incubation process integrating lysis, reduction, alkylation, and digestion generates peptide samples directly from tissues in [≤] 1.5 h. For FFPE tissues, concurrent deparaffinization, rehydration, and de- crosslinking is achieved within 0.5 h, followed by one-step peptide preparation. Furthermore, our workflows eliminate desalting and offline cleanup steps, thereby reducing variability and total processing time. Using our methods, we identified up to [~]10,000 protein groups and [~]150,000 peptides across multiple mouse organs on timsTOF Pro. Repeatability was high (pairwise Pearsons r > 0.96 across six experimental replicates), with dynamic ranges spanning 6-7 orders of magnitude. Organ-enriched protein analysis identified functionally distinct proteins unique to each tissue Paired FF and FFPE analyses revealed preservation-induced shifts, with FFPE tissues showing reduced detection of membrane-associated and respiratory proteins, including mitochondrial Complex I. Together, our fast and simplified workflows enable deep tissue proteomics for large-scale clinical and translational studies in a cost- effective and widely-accessible manner.

biochemistry↗

bioRxiv2025

JAAG: a JSON input file Assembler for AlphaFold 3 with Glycan integration

Standalone AlphaFold 3 (AF3) models proteins, post-translational modifications, and ligands (including glycans) from a single JSON input file. Plausible glycan stereochemistry is more consistently achieved when monosaccharides are specified as Chemical Component Dictionary (CCD) entries and connected using bondedAtomPairs (BAP) syntax. Although this approach preserves glycan stereochemistry, assembling JSON input files manually is challenging due to the diversity of monosaccharides, linkages, branching, and structural complexity. To simplify this process, we developed JAAG (JSON input file Assembler for AlphaFold 3 with Glycan integration (https://biofgreat.org/JAAG and https://github.com/chinchc/JAAG)), a web-based graphical interface that streamlines AF3 JSON file creation, reduces errors, and facilitates modeling of glycans and glycan-macromolecule interactions.

bioinformatics↗

bioRxiv2025

Iron Metabolism and Antioxidant Defense: The Role of LI-rTMS in Cerebral Ischemia-Reperfusion

BACKGROUNDTreating cerebral ischemia/reperfusion injury (CIRI) is challenging, with iron metabolism imbalances and oxidative stress worsening the condition. While low-intensity repetitive transcranial magnetic stimulation (LI-rTMS) shows potential in brain protection, its effects on iron processing and antioxidant use are unclear. This study explored LI-rTMSs role in regulating iron homeostasis and antioxidant defense for potential therapeutic use in CIRI. METHODSA rat model of CIRI was established using a filament insertion technique, followed by neurological and infarct volume assessments. In PC12 cells, oxidative damage was induced with H2O2 or ferric ammonium citrate (FAC), then treated with LI-rTMS or deferoxamine (DFP). Parameters measured included oxidative stress markers, iron metabolism markers, and mitochondrial integrity. Gene knockdown and overexpression experiments explored mechanisms involving LI-rTMS and ACSL4. RESULTSLI-rTMS improved neurological deficits by boosting GPX4 activity and inhibiting the ACSL4-LPCAT3-LOX axis, reducing lipid peroxidation. It restored iron balance by lowering TFR and DMT1, decreasing ferritin and hepcidin, and increasing FPN for better iron efflux. LI-rTMS also prevented the Fenton reaction, reduced ROS production, and maintained mitochondrial structure and transmembrane potential. CONCLUSIONSLI-rTMS offers neuroprotection by regulating iron homeostasis through dual pathways: boosting export (via FPN) and reducing uptake/storage (via TFR/DMT1/FE). It also provides ACSL4-dependent antioxidant benefits, suggesting its potential to prevent ferroptosis in CIRI.

biophysics↗

bioRxiv2025

MORC2 Mediates Transcriptional Regulation Through Liquid-Liquid Phase Separation and DNA Binding

MORC2 is a chromatin-associated ATPase essential for transcriptional silencing and genome stability, yet the biophysical principles governing its regulatory activity remain elusive. Here, we demonstrate that full-length MORC2 undergoes biomolecular condensation to form dynamic nuclear assemblies, a process fundamentally required for its repressor function. Endogenous MORC2 forms discrete, dynamic condensates in neurons from EGFP-MORC2 knock-in mice, supporting the physiological relevance of these assemblies in vivo. Mechanistically, a 3.1 [A] crystal structure of coiled-coil 3 (CC3) identifies a dimeric scaffold that serves as a structural hub, while multivalent sticker interactions between an intrinsically disordered region (IDR) and a newly defined IDR-binding domain (IBD) drive condensation. We show that DNA acts as a molecular scaffold that triggers MORC2 condensation, which in turn allosterically stimulates its ATPase activity. Critically, by employing a "killswitch" strategy to decouple assembly from internal fluidity, we reveal that only dynamic MORC2 condensates--not static aggregates or condensation-deficient mutants--can restore transcriptional repression in MORC2-knockout cells. Furthermore, pathogenic variants linked to CMT2Z and SMA differentially perturb these material properties and enzymatic turnover, providing a mechanistic link between condensate dysregulation and human neuropathies. Together, our findings establish a DNA-templated condensation mechanism for MORC2 and provide a molecular framework for understanding how the material state of chromatin-associated machinery dictates gene regulation and disease pathogenesis

cell biology↗

bioRxiv2025

3D-Printed Scaffolds Encapsulating Red Blood Cell Extracellular Vesicles for MicroRNA Delivery

Small non-coding RNAs (sncRNA) hold promising therapeutic potential. However, their clinical application is hindered by the poor cytocompatibility and limited transfection efficiency of conventional delivery vectors. In contrast, red blood cell-derived extracellular vesicles (RBCEVs) offer a safer, more efficient, and cost-effective alternative. Given the limited studies on the application of RBCEVs in the central nervous system (CNS) which is characterized by the presence of sensitive cell types with inherently low transfection efficiency, we hypothesized that RBCEVs could serve as a safe and effective sncRNA delivery vector for CNS applications, and that their incorporation into 3D-printed scaffolds could enable sustained and localized delivery of therapeutic sncRNAs. To test this, the uptake and gene silencing performance of RBCEVs were examined in primary CNS cell types, including astrocytes, neurons, oligodendrocyte precursor cells (OPCs), and microglia. While over 70% of OPCs and microglia internalized RBCEVs, uptake in neurons and astrocytes remained below 40%, indicating cell-type-specific uptake efficiency. Additionally, RBCEVs-mediated delivery of siRNA resulted in the highest gene knockdown efficiency in OPCs (74.2%), while triggering less than 30% gene knockdown in other cell types. Next, RBCEVs-encapsulated scaffolds were fabricated using digital light processing (DLP) 3D printing, enabling the sustained release of miR-219/miR-338-loaded RBCEVs for at least 21 days in vitro, which resulted in effective gene silencing that promoted OPC differentiation and myelination. Using spinal cord injury (SCI) as a proof-of-concept, scaffold-mediated delivery of RBCEVs-miR-219/miR-338 significantly promoted OPC differentiation and maturation in vivo as evidenced by increased CC1 mature oligodendrocytes and reduced PDGFR undifferentiated OPCs (p < 0.001). Taken together, these results demonstrate the therapeutic potential of combining RBCEVs with DLP-printed scaffolds for localized and sustained sncRNA delivery in CNS disease treatment.

bioengineering↗

bioRxiv2025

Multi-omic dereplication of antibiotic production by diffusion chamber isolated bacteria from Australian soils

Soil bacteria are a major source of clinically useful antibiotics, yet the majority of soil-dwelling microorganisms remain uncultivable by standard laboratory methods. To access this untapped microbial diversity, we employed microbial diffusion chambers to isolate bacteria from ten Australian soil samples. A total of 1,218 bacterial isolates were recovered, representing a diverse collection spanning 61 genera from 32 families, covering the major known phyla of soil bacteria. Antibiotic activity screening revealed that 16% of isolates inhibited the growth of at least one of E. coli or S. aureus, with 120 isolates displaying activity against multidrug-resistant pathogens including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). Mass spectrometry-based dereplication using GNPS identified known antibiotics in 33% of bioactive strains, including actinomycin D, nonactins, and valinomycin. Genomic analysis confirmed the presence of corresponding biosynthetic gene clusters (BGCs), while targeted analysis of selected strains uncovered production of additional antibiotics such as nigericin and streptothricin that were not initially detected by mass spectrometry. Our results demonstrate that diffusion chambers enhance bacterial recovery from soil and show the benefits of a combined pipeline including bioactivity screening, mass spectrometry, and genomics for effective antibiotic dereplication and discovery. Impact StatementThis study delivers a significant advance in natural product discovery by demonstrating that microbial diffusion chambers can dramatically improve the recovery of diverse soil bacteria with antibiotic-producing potential from Australian soil samples. By integrating in situ cultivation with high-throughput screening, mass spectrometry-based dereplication and genome mining, this study yielded more than 1,200 bacterial isolates--including many with activity against multidrug-resistant pathogens--and confirms the production of both known and previously undetected antibiotics. The discovery of streptothricin production via genomics, despite its absence from mass spectrometry data, underscores the power of a multi-layered dereplication strategy. This work not only validates the utility of diffusion chambers for unlocking the "rare biosphere" of uncultivable microbes but also highlights critical methodological refinements to diversify antibiotic-producing strains beyond Streptomyces. The findings will inform and accelerate future efforts to discover urgently needed antibiotics from environmental microbiomes. Data SummaryThe whole-genome sequences were deposited in the National Center for Biotechnology Information National Library of Medicine under BioProject accession number PRJNA1272227.

microbiology↗

bioRxiv2025

Engineering B cells to Express Fully Customizable Antibodies with Enhanced Fc Functions

Genome editing within the constant region of the immunoglobulin Heavy chain locus (IGH) can reprogram B cells to express Heavy chain only antibodies (HCAbs) containing custom antigen-recognition domains. HCAb-engineered cells express both surface B cell receptor (BCR) and secreted antibody isoforms and respond to antigen. By selecting alternate editing sites within IGH, we extended this approach to also allow customization of the constant (Fc) domain of the Heavy chain, producing HCAbs with enhanced effector functions or containing mutations to extend antibody half-life. We also introduced mutations to force obligate HCAb homodimers and prevent unwanted pairing with endogenous antibody chains. Finally, we showed that additional domains could be accommodated at the HCAb C-terminus and preferentially expressed in the secreted isoform. Together these data demonstrate the flexibility of the HCAb editing platform to express fully customized molecules that take advantage of the properties of B cells.

immunology↗

bioRxiv2025

High-throughput Single-cell Proteomics Enabled by an Integrated Hyperplexing and Automatic Labelling Approach without Fractionation

Single-cell proteomics (scProteomics) enables comprehensive analysis of protein composition, expression and functions at the single-cell level. While label-free techniques have generated promising results, achieving high-throughput scProteomics remains a substantial challenge. In this study, we present an approach that increases scProteomics throughput by approximately 30-fold through the true integration of isobaric tags (IBT) with tandem mass tags (TMT), a method we term Integral-Hyperplex. Due to remarkable differences in signal response between TMT16 and IBT16 reporter ions, we implemented two normalization strategies to ensure accurate and integrated quantification: (1) the inclusion of a normalization channel in both IBT and TMT groups to serve as internal standards; and (2) the generation of protein-specific conversion factors between IBT16 and TMT16 signals. We validated the quantification accuracy of the Integral-Hyperplex method by labeling HeLa digests at varying ratios. Furthermore, we demonstrated fully automated labeling on the active-matrix digital microfluidics chip, consuming only 12 nL of labeling reagent per single cell and with a reaction volume as low as 20 nL. Our approach was validated through proof-of-principle quantification experiments across three types of single cells. Approximately 2,000 protein groups were quantified per cell, and the three cell types can be well clustered, confirming the reliability of the Integral-Hyperplex approach. Approximately 300 samples can be analyzed per day due to insufficient resolution of timsTOF SCP. Throughput can be further enhanced using TMT32, additional labeling reagents, and more advanced mass spectrometers such as Orbitrap Astral and timsTOF Ultra 2, and our approach is theoretically capable of analyzing up to [~]2,000 single cells per day.

biochemistry↗

bioRxiv2025

Secondary structure transitions and dual PIP2 binding define cardiac KCNQ1-KCNE1 channel gating

The KCNQ1+KCNE1 potassium channel complex forms the slow delayed rectifier current (IKs) critical for cardiac repolarization. Loss-of-function variants in KCNQ1 and KCNE1 cause long QT syndrome types 1 and 5 (LQT1/LQT5), accounting for over one-third of clinical LQTS cases. Despite prior structural work on KCNQ1 and KCNQ1+KCNE3, the structural basis of KCNQ1+KCNE1 remains unresolved. Using cryo-EM and electrophysiology, we determined high-resolution (2.5-3.4 [A]) structures of human KCNQ1+KCNE1 in both closed and open states. KCNE1 occupies a pivotal position at the interface of three KCNQ1 subunits, inducing seven "helix-to-loop" transitions in KCNQ1 transmembrane segments. These structural rearrangements: 1) stabilize the closed pore and the conformation of the intermediate voltage-sensing domain, thereby determining channel gating, ion permeation, and single channel conductance; 2) enable a dual-PIP2 modulation mechanism, where one PIP2 occupies the canonical site, while the second PIP2 bridges the S4-S5 linker, KCNE1, and the adjacent S6, stabilizing channel opening; 3) create a fenestration capable of binding compounds specific for KCNQ1+KCNE1 (e.g., AC-1). Together, these findings reveal a previously unrecognized large-scale secondary structural transition during ion channel gating that fine-tunes IKs function and provides a foundation for targeted LQTS therapy development.

biophysics↗

bioRxiv2025

Regulation of essential hepatocyte functions and identity by super-enhancers in health and disease

Physiologically, hepatocytes perform an estimated 500 essential liver functions to ensure systemic homeostasis. The mechanisms how hepatocytes maintain these numerous crucial functions in response to physiological and pathophysiological challenges are largely unknown. In this study, we found that vital liver function genes (e.g., HNF4A, ALB, coagulation factors, and SLC2A2) in hepatocytes possess super-enhancers. Interfering with the super-enhancers by dCas9-sgRNA remarkably decreases the expression of these genes. Quiescent liver progenitor cells (LPCs) do not have active super-enhancers in vital liver function genes. In acute liver failure (ALF) caused by massive hepatic necrosis, activated LPCs perform liver function and differentiate into hepatocytes to rescue patients lives. We show that activated LPCs gradually form super-enhancers in liver function genes (e.g., HNF4A, ALB, and coagulation factors) during proliferation and differentiation. These super-enhancers are regulated by FOXA2 through the recruitment of HNF4 a, p300 and Mediators in most liver function genes, such as ALB and coagulation factors. However, super-enhancers in some genes (e.g., SLC2A2) are FOXA2-indenpendent. Hepatic FOXA2 expression is closely associated with the clinical outcome of ALF. In a cohort of ALF patients, robust FOXA2 is observed only in the surviving patients. Collectively, super-enhancers represent a critical epigenetic regulatory mechanism that enables rapidly enhanced transcription of liver function genes in response to pathophysiological challenges. In urgent clinical syndrome such as ALF, LPCs rescue liver function by rapid formation of super-enhancers in vital genes.

molecular biology↗

bioRxiv2025

Towards Unmanned Proteomics Data Generation: A Fully Automated Sample-to-Data System for Proteomic Experiments

The {pi}-HuB project requires proteomic measurements of millions of low-input samples that are challenging with current technology. Here, we introduce a pilot {pi}-HuB data factory that features a fully automated sample-to-data system to enable high-throughput digitization of human samples. Our platform, as a proof-of-concept towards unmanned proteomics, was demonstrated to show longitudinal robustness and applied for spatial proteomics and the profiling of plasma and cell lines, thereby serving as the workhorse to drive {pi}-HuB.

biochemistry↗

bioRxiv2025

Neurocomputational Mechanisms Linking Future Interaction Prospects to Reactive and Proactive Costly Punishment

Costly punishment within social bonds manifests as both reactive penalties for transgressions and proactive sanctions against fair behaviors, yet a unified neurocomputational framework remains elusive. Combining neuroimaging and computational modeling, this study examined how future interaction prospects--a key element of social bonds--modulate reactive and proactive punishment. Participants acted as second- or third-party punishers, responding to allocation offers from individuals with or without future interactions. Results showed that participants imposed harsher punishment on both fair and unfair offers from individuals they did not expect to interact with, aligning with lower self-reported social closeness. Heightened provocation sensitivity, reflected in dorsal anterior cingulate cortex activity, drove the increased reactive punishment toward wrongdoers without future interactions, whereas punishment of future-interacting transgressors was associated with enhanced dorsolateral and dorsomedial prefrontal cortex (dlPFC, dmPFC) activity. A stronger preference for relative advantage and reduced harm sensitivity, linked to dlPFC and temporoparietal junction activity, mediated greater proactive punishment towards non-future-interacting individuals. Moreover, proactive punishment and underlying neurocognitive processes followed a collective retaliation pattern, increasing after unfair (vs. fair) behavior from another non-future-interacting individual. These findings establish a unified neurocomputational framework for understanding how future interaction prospects regulate costly punishment, integrating reactive and proactive motives within social bonds.

neuroscience↗

bioRxiv2025

An embryonic artery-forming niche reactivates in pulmonary arterial hypertension

Developmental programs that orchestrate cell fate and tissue architecture during organogenesis can cause disease when reactivated in adults. Here we identify a population of endothelial cells (ECs) defined by the pioneer factor early B cell factor 1 (EBF1) that controls both pulmonary artery (PA) morphogenesis and pulmonary arterial hypertension (PAH). During embryonic development, the PA emerges from an endothelial niche harbored within the vascular plexus, where Aplnr+ endothelial progenitors give rise to both arterial ECs and EBF1+ ECs. Rather than directly incorporating into the PA intima, EBF1+ ECs control the branching and maturation of the PA tree through paracrine vasculotrophic signals that direct plexus expansion, arterialization, and mural cell recruitment. Although essential for development, most EBF1+ ECs disappear upon completion of PA morphogenesis. In adult PAH, vascular injury reactivates this developmental program: normally quiescent general capillary ECs re-enter the cell cycle and differentiate into arterial ECs and EBF1+ ECs, reconstituting this artery-forming niche in a maladaptive reprise. Unlike their transient embryonic counterparts, EBF1+ ECs persist within neointimal lesions and express vasculotrophic signals associated with pathological PA remodeling. Capillary-restricted Ebf1 induction combined with endothelial injury recapitulates this program, driving neo-arterialization, neointimal formation, and severe PAH. Conversely, endothelial-targeted AAV-mediated Ebf1 knockdown achieves complete protection in a preclinical model of disease, demonstrating that endothelial EBF1 is necessary for PAH pathogenesis. These findings demonstrate that reactivation and persistence of a transient embryonic artery-forming niche in adulthood can promote pathological vascular remodeling and PAH.

developmental biology↗

bioRxiv2025

Saddle Curvature Association of nsP1 Facilitates the Replication Complex Assembly of Chikungunya Virus in Cells

The replication of positive-sense RNA viruses, including the pathogenic SARS-CoV-1 and -2, DENV, and ZIKV, often takes place in curved cellular membrane compartments of tens to hundreds of nanometers in diameter within host cells. The non-structural proteins (nsPs) of viruses are found to critically control the formation and maintenance of such unique nanoscale membrane structures. However, the molecular mechanism underlying the association and assembly of nsPs around curved membranes has remained elusive, due to the technical difficulties of imaging the nanoscale interaction in live cells. In this study, we leveraged vertically aligned nanostructures to define membrane curvatures in live cells and investigated the assembly of viral nsPs on these curved membranes. Using Chikungunya virus as a model system, we found that its nsP1 was preferentially bound to and stabilized around positively curved membrane sites and the preference became more apparent as the radius of curvature decreased to 150 nm or smaller. This preferential accumulation was mainly attributed to the hydrophobic residues on recently identified membrane association loops (MA loops) of each nsP1 monomer. Molecular dynamics simulations further confirmed the improved binding kinetics and stability of nsP1 on positively curved membranes, especially when a 12-mer ring was formed by the nsP1 dodecamer. More interestingly, a saddle curvature association was enabled by the 3D coordination of nsP1 monomers along the dodecamer ring, where the MA loops of individual nsP1 monomers sensed a wide range of the positively curved membrane in the x-z plane while the rigid nsP1 dodecamer ring stabilized the negative curvature in the x-y plane. Its strong coupling to the saddle curvature fulfilled the need to constrain the neck of the membrane spherule for viral replication. Strikingly, productive CHIKV replication exhibited strong enrichment on patterned nanostructure array, proving the effectiveness of membrane curvature-guided assembly of the functional replication complex. Our findings revealed that the cell membrane facilitated the local enrichment of viral nsPs in a curvature- dependent manner. It opens up membrane curvature modulation as a new dimension to dissect the formation and regulation of membrane compartments for viral replication.

biophysics↗