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Biology subjects

Gu, Z.

Publications and source records attributed to Gu, Z..

At least 19 recordsLinked to original sources
bioRxiv2026

Systematic mapping of enhancers, silencers, and topological elements with prime editing deletion screens

Noncoding regulatory elements in the human genome can control gene expression through distinct mechanisms, including acting as enhancers, silencers, or topological elements. However, we lack tools to identify all such classes systematically and quantify their effects on gene expression in an endogenous genomic context. Here we develop Swap-seq, a method that combines pooled twin prime editing with flow-sorting to delete hundreds of endogenous regulatory sequences and measure their quantitative effects on the expression of a nearby gene. We apply Swap-seq to dissect the regulatory elements that control PPIF expression in THP-1 monocytes. We quantify the effects of distal and intronic enhancers, characterize CTCF insulators, and discover a silencer that regulates distal genes through histone deacetylase (HDAC)-mediated repression of neighboring enhancers. Hundreds of other genomic elements share its chromatin signatures and transcription factor binding sites, suggesting that this silencer represents a broader class of repressive elements. We leverage Swap-seq data to benchmark sequence-to-function models and show that they often capture the local activity of regulatory elements but fail to link them to distal target genes. Swap-seq thus provides a generalizable tool to discover regulatory elements across mechanistic classes, characterize their effects on gene expression, and generate large-scale datasets for evaluating sequence-to-function models.

genomics↗
bioRxiv2026

Magel2 deficiency drives microglial synaptic engulfment and alters neuron-microglia interactions in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by hypothalamic dysfunction, developmental delay, hyperphagia, and cognitive impairment, yet the cellular mechanisms underlying circuit abnormalities remain unclear. Here, we show that loss of the imprinted gene Magel2 remodels microglial state and function in a mouse model of PWS. Three-dimensional morphometric analysis of hypothalamic microglia revealed reduced structural complexity and contracted territorial domains, emerging early in development and largely independent of obesity. Single-nucleus RNA sequencing of hypothalamic brain tissue identified extensive transcriptional reprogramming involving immune signaling, cellular communication, ribosome function, synaptic organization, and protein translation, with stronger effects in females. Magel2 deficiency also increased microglia-neuron contacts and synaptic engulfment, accompanied by reduced synaptic marker density, suggesting aberrant refinement of hypothalamic circuits. Analyses of human post-mortem hypothalamic tissue from individuals with PWS confirmed microglial structural alterations and increased complement engagement. Ligand-receptor inference further revealed reorganization of microglia-centered communication networks, including altered adhesion, trophic, and immune signaling consistent with enhanced phagocytic states. Together, these findings identify microglial remodeling and increased synaptic engagement as central features of Magel2 deficiency, implicate microglia in hypothalamic circuit dysfunction in PWS, and highlight excessive synaptic pruning as a novel dysfunctional mechanism of PWS.

neuroscience↗
bioRxiv2026

A quantum state of mitochondria in the living cell

The high energy-efficiency of life is hard to understand only with classical physics. Many efforts have been made to study its mechanism based on quantum mechanics; the progress is nevertheless slow due to lack of experimental evidence with living cells. Here, combining experiments on cells, tissues and mitochondria with a theoretical model, we demonstrate a quantum state of mitochondria, which can be employed to modulate ATP production in living cells. We found an anomalous 71.0-THz oscillation mode only in living cells and tissues, which is highly determined by intact structure of mitochondria, and cannot be assigned to any specific molecules. Based on experimental data, a quantum model of light-matter coupling was introduced to trace the origin of this mode. Our calculations suggest a quantum superposition state of functional mitochondrion that forms by the coupling of light and lipid CH2 bonds in functional cristae, and induces a splitting of the intrinsic CH2 vibration mode of 87 THz to two levels at 71 THz and 103 THz, respectively. The former can be observed only in living cells and tissues; whereas the latter falls in the range (90-110 THz) of biomolecular and water vibrations, thus indistinguishable. Additional experiments revealed this mitochondrial quantum state able to serve as an efficient channel to modulate ATP production. Our findings provide a quantum mechanics view for understanding living cells, and it will be interesting to further explore whether such quantum state could act as a channel for energy metabolism, and even information transmission in life.

biophysics↗
bioRxiv2026

Ileal Gpbar1 gates depressive phenotypes via gut to brain "vagal-NTS-PVN"GABAergic axis

Depression represents a typical mental condition, yet whether intestinal metabolic signals drive central neural circuits remains unclear. Here we identify ileal enteric neuronal Gpbar1 as a previously unrecognized peripheral node that coordinates gut-to-brain communication to prevent depression-like behavior through a vagus-dependent, nucleus tractus solitaries (NTS)-paraventricular nucleus (PVN) signaling axis. The enteric plexus Gpbar1 is predominantly expressed on a subpopulation of GAD1-positive GABAergic neurons. Chronic restraint stress suppresses Gpbar1 expression, triggers glycolytic reprogramming and mitochondrial distress in both ileum and hypothalamus. Oral Gpbar1 agonism with INT-777 reverses hypothalamic HK2/TOM20 alterations and behavioral abnormalities by enhanced ileal mTOR/HIF-1 alpah signaling and glycolysis-related metabolite shifts, an effect specifically abolished by subdiaphragmatic vagotomy or chemogenetic silencing of PVN GABAergic neurons. Our findings establish ileal Gpbar1 as a gut-derived metabolic sensor that engages a defined vagal-brainstem-hypothalamic inhibitory circuit to regulate depressive phenotypes, shifting the roadmap from brain-centered to gut-initiated antidepressant mechanisms and unveiling a compelling peripheral therapeutic strategy that bypasses intractable central brain-directed intervention.

neuroscience↗
bioRxiv2026

A biologically supported global RNA architecture of cucumber mosaic virus satellite RNA

Satellite RNAs (satRNAs) are parasitic subviral agents whose biological activities are mediated largely by specific sequence determinants and structured RNA elements. Establishing biologically supported global RNA structures is therefore essential for understanding how RNA architecture underlies satRNA functions. Cucumber mosaic virus (CMV) satRNA is one of the best-characterized models for investigating satRNA structure-function relationships; however, a biologically supported global RNA architecture of CMV satRNA has yet to be established. Here, we applied AlphaFold3 modeling to predict the global structure of CMV satRNA T1 (sat-T1). Initial full-length structure modeling generated multiple long-distance interactions that lacked biological support. We therefore used fragment-based modeling, combined with chemical probing, evolutionary covariation, and compensatory mutagenesis, to derive a biologically supported global secondary structure. To determine whether structurally distant regions could interact in the context of the full-length RNA, we engineered a structure-guided T1-ZD mutant that preserved the supported secondary structure while reducing alternative base-pairing possibilities. Full-length AlphaFold3 modeling of T1-ZD largely recapitulated the proposed architecture, while one predicted model revealed a long-distance interaction that was subsequently supported by compensatory mutagenesis analysis. These findings suggest that the 3' terminus of sat-T1 may undergo conformational switching between alternative structural states. Together, our work establishes a biologically supported global RNA architecture for CMV sat-T1 and provides a structural framework for investigating the molecular basis of satRNA function.

microbiology↗
bioRxiv2026

Spoken Recall Reveals Lexical and Mnemonic Function Differences in Temporal Lobe Epilepsy Patients

Background and Objectives: Word-finding difficulty is common in healthy aging and in neurologic disorders, including temporal lobe epilepsy (TLE) and early Alzheimer disease. Standard language measures have limited sensitivity for detecting subtle or longitudinal changes in spontaneous speech. We examined whether natural language processing and acoustic analysis of spoken biographical recall could identify lexical and temporal speech features associated with language and memory performance in TLE. Methods: We conducted a cross-sectional observational study of spoken recall during a Famous Faces biographical memory task. Adults with TLE and healthy controls (HCs) viewed 20 famous faces and spontaneously recalled biographical details. Speech was transcribed and diarized using automated tools. Lexical measures included word counts and lexical index (ratio of rare to common words). Acoustic measures included utterance and pause duration and pause frequency. Features were compared between groups and correlated with neuropsychological measures, including Montreal Cognitive Assessment (MoCA), Boston Naming Test (BNT), delayed recall, education, and biographical recall accuracy Results: Eighty-one adults participated (51 TLE, 30 HCs). Lexical measures did not differ between groups. In TLE, lexical index correlated with BNT performance (rs=0.62) and MoCA score (rs=0.35). Compared with HCs, participants with TLE produced shorter utterances (5.54 {+/-} 2.50 vs. 6.59 {+/-} 2.63; Cohen's d=0.41, 95% CI -0.05 to 0.86, p=0.041), shorter pauses (0.61 {+/-} 0.21 vs 0.67 {+/-} 0.22, Cohen's d=0.29, 95% CI -0.16 to 0.74, p=0.043), and more frequent pauses (10.81 {+/-} 3.30 vs 9.29 {+/-} 3.59, Cohen's d=-0.45, 95% CI -0.90 to 0.01, p=0.036). Higher education was associated with longer utterances, longer pauses, and lower pause frequency, without evidence of a diagnosis-by-education interaction. Faster utterance rate was associated with better biographical recall in both groups, while higher pause rate was associated with worse recall in TLE. Discussion: Speech-derived lexical and temporal features from naturalistic recall capture clinically relevant variation in language and memory-related performance. Although lexical output did not distinguish TLE from HCs, lexical richness tracked naming and global cognition in TLE, while temporal speech features related to recall performance. These findings support the potential of automated speech analysis as a digital behavioral biomarker for word-finding difficulty in neurologic populations.

neuroscience↗
bioRxiv2026

Loss of calbindin and rise in pT217-tau in aging monkey prefrontal cortical dendrites

INTRODUCTION: Tau pathology in Alzheimers disease preferentially afflicts excitatory neurons in the limbic and association cortices that utilize high levels of calcium signaling to perform cognitive operations. This includes the layer III pyramidal cells in the dorsolateral prefrontal cortex (dlPFC) that subserve higher cognition, which express the calcium-binding protein, calbindin, when young and healthy, but lose calbindin and develop tangles and degenerate in Alzheimers disease (AD). These data suggest that loss of calbindin may be associated with the emergence of tau pathology. However, the relationship between calbindin and early-stage, soluble tau pathology is challenging to study in human brains, as soluble pTau dephosphorylates within 15min postmortem. In contrast, the relationship between calbindin and soluble pT217-tau expression can be studied in aging macaques with naturally-occurring tau pathology, where perfusion fixation is possible to capture phosphorylation state in situ. METHODS: The current study used multiple-label-immunofluorescence to label MAP2-positive dlPFC layer III pyramidal cells for calbindin and pT217-tau in macaque brains across the adult age span (8-34.5yrs). The study employed a semi-automated CellProfiler workflow to identify labeled pyramidal cell dendrites the cellular compartment where tau pathology begins in AD. RESULTS: Calbindin expression decreased with age, while pT217Tau increased with age. Specifically, the ratio of calbindin/pT217-tau within a dendrite decreased with age, and was especially prominent in the aged macaques with long-term inflammatory disorders. DISCUSSION: These data suggest that the loss of calbindin in dendrites with advancing age, and especially with inflammation, contributes to the rise of tau pathology and the risk of AD.

neuroscience↗
bioRxiv2026

Accelerated lung evolution associated with end-Permian and end-Triassic mass extinctions

The end-Permian and end-Triassic mass extinctions, driven by massive catastrophic volcanism and prolonged hypoxia, fundamentally reshaped life on Earth. However, the genomic impacts of these two biodiversity crises on living organisms remain largely unknown. Here, we performed a genome-wide screening to identify accelerated evolved regions in the ancestral lineage of mammals that survived both extinction events. Nearly all (20/21) of these accelerated regions were located in protein-coding sequences, and 81% (17/21) were found to be associated with lung function. We further extended our analysis to three additional vertebrate lineages that experienced either one or both of the mass extinctions. Similar genomic signatures, involving accelerated evolution of lung-related genes, were also observed in these non-mammalian lineages. Collectively, these findings suggest that adaptation of lung-related genes to prolonged hypoxia may have occurred during the two mass extinction events, potentially driving a second evolutionary stage of the lung following the vertebrate transition to land.

evolutionary biology↗
bioRxiv2026

Adrenomedullin Restores Mitochondrial Bioenergetics and Rescues Interneuron Phenotypes in Human Models of 22q11.2 Deletion Syndrome

22q11.2 deletion syndrome (22q11.2DS), also known as DiGeorge syndrome, is the strongest genetic risk factor for schizophrenia, yet the cellular mechanisms underlying this vulnerability remain incompletely understood. Using iPSC-derived human subpallial organoids (hSOs) and forebrain assembloids (hFAs), we identified key 22q11.2DS cellular and molecular phenotypes in migrating cortical interneurons and rescued them with Adrenomedullin (ADM), a 52-amino-acid peptide hormone that acts through the CLR/RAMP2 receptor complex. Specifically, we discover that 22q11.2DS interneurons exhibit impaired migration patterns, and that this is associated with excessive mitochondrial fragmentation, reduced oxidative phosphorylation, and dysregulated calcium signaling. Transcriptomic analysis reveals a glycolytic shift and widespread downregulation of oxidative phosphorylation genes. Next, we identify ADM as a potent rescue agent that restores mitochondrial morphology, membrane potential, respiration, calcium homeostasis, actin retrograde flow, and interneuron migration. Mechanistically, we find that ADM signals through two parallel pathways: PKA-mediated DRP1 Ser637 phosphorylation, which promotes mitochondrial fusion, and PLC-mediated calcium signaling, which normalizes actin dynamics. These phenotypes and their rescue are recapitulated in primary developing human cortical tissue carrying the 22q11.2 deletion. Overall, our study establishes a mitochondrial-cytoskeletal axis as a novel biological mechanism underlying the alterations observed in neuronal development in human preclinical models of 22q11.2DS and identifies possible therapeutic molecular targets for 22q11.2DS-associated neuropsychiatric pathology. HIGHLIGHTSO_LIInhibitory neurons in 22q11.2DS organoids and assembloids show mitochondrial fragmentation and impaired migration C_LIO_LIADM rescues mitochondrial morphology, respiration, and interneuron migration C_LIO_LIPKA and PLC pathways mediate separate arms of ADMs rescue mechanism C_LIO_LIPhenotypes and ADM rescue are validated in human cortical tissue C_LI

neuroscience↗
bioRxiv2026

The External Globus Pallidus is a Basal Ganglia Output Hub with Action-Specific Circuits

The external globus pallidus (GPe) is traditionally viewed as a homogeneous relay in the indirect basal ganglia pathway that broadly suppresses movement. Using whole-brain anterograde axon mapping, rabies tracing, single-neuron reconstruction, and single-nucleus RNA sequencing, we reveal that the GPe is a major basal ganglia output nucleus, composed of anatomically and molecularly distinct populations. Besides the neurons with canonical projections, and projections to striatum and cortex, the GPe contains specific neuronal populations that target the thalamus and brainstem directly, including the parafascicular thalamus (GPePf) and the pedunculopontine nucleus (GPePPN). These projection-defined subpopulations exhibit distinct behavioral functions. GPe-PPN neurons are selectively suppressed at locomotor onset, and bidirectional manipulation of this pathway is sufficient to promote or suppress locomotion. Notably, D2-MSN stimulation upstream of these neurons evokes locomotion, and co-activation of GPePPN pathway blocks this D2-MSN-evoked locomotion, demonstrating a disinhibitory circuit for action stemming from D2-MSNs. In contrast, GPePf neurons are not engaged during locomotion but are selectively recruited during skilled forelimb actions, and their activation disrupts forelimb movements without affecting locomotion. Together, these findings establish the GPe as a basal ganglia output hub composed of modules that mediate distinct behaviors. This organization revises canonical models of the indirect pathway by demonstrating that D2-MSNs can also facilitate, rather than only suppress, movement depending on the downstream GPe output channels they engage. In briefThe external globus pallidus (GPe), classically considered a relatively homogeneous relay within the indirect basal ganglia pathway, is revealed here as a major basal ganglia output hub. Distinct GPe subpopulations, defined by transcriptomic identity and projection target, form parallel channels to cortical, thalamic and brainstem structures with action-specific functions. These findings uncover a disinhibitory mechanism through which D2-MSNs can facilitate behavior, revising canonical models of basal ganglia function. HighlightsBrain-wide mapping reveals the GPe as a major basal ganglia output node GPe contains novel cell types defined by transcriptomic identity and projection specificity Projection-specific GPe circuits differentially control locomotion and skilled forelimb actions D2-MSNs can disinhibit downstream targets via specific GPe projections and promote action.

neuroscience↗
bioRxiv2026

Knockdown of the long isoform of the prolactin receptor selectively targets pathogenic immune cells and averts lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by chronic inflammation in multiple organ systems. While a clinical association between elevated levels of the hormone/cytokine, prolactin (PRL), and exacerbation of SLE has been recognized for some time, little is known about the mechanisms through which PRL affects the course of this disease. Here, we show that immune cells in SLE have aberrant splicing of the prolactin receptor (PRLR) such that the ratio of the long to short splice variants is increased. To determine whether the change in PRLR isoform expression was causal in this disease, we used a splice-modulating oligomer (SMO) that knocked down expression of the long splice variant (LFPRLR). Using patient samples ex vivo, SLE-prone mice in vivo, high-dimensional flow cytometry and single-cell RNA-sequencing, we demonstrate that the aberrant PRLR isoform expression in SLE both directly and indirectly drives production of autoreactive immune cell phenotypes. Thus, LFPRLR knockdown decreased the expression of type I interferon signaling/response genes known to be biomarkers and hub genes for SLE, reduced immunoglobulins with signatures considered autoreactive, and averted glomerular kidney damage in SLE-prone mice. Importantly, LFPRLR knockdown reduced pathogenic B cells and other immune subsets that drive B-cell activation, without negative impact on healthy donor counterparts. Current treatments for SLE adversely affect healthy cells and do not concurrently eradicate multiple pathogenic immune subsets. Since LFPRLR SMO does not share these disadvantages, knockdown of the LFPRLR represents a potential treatment strategy for SLE that merits further investigation. Graphical AbstractThe LFPRLR represents an attractive therapeutic target in SLE. (Left) In addition to increased pituitary/circulating PRL, individuals with SLE exhibit aberrant increases in the production of autocrine/paracrine PRL by immune cells, and in their expression of specifically the long isoform (LF) of the PRLR. (Middle) Expression of the LFPRLR specifically enhances autoreactive immunophenotypes and promotes lupus nephritis. (Right) A splice modulating oligomer (SMO), that prevents synthesis of only the LFPRLR but not the short PRLR isoforms, reduces pathogenic immunophenotypes without affecting the normal counterparts of immune cells.

immunology↗
bioRxiv2026

Leveraging Large Language Models to Extract Prognostic Pathology Features in Ewing Sarcoma

BackgroundCurrent risk stratification for Ewing sarcoma relies heavily on clinical factors such as metastatic status, failing to capture histologic heterogeneity as a potential prognostic indicator. Although pathology reports contain rich biological data, this information remains locked in unstructured narrative text, limiting large-scale retrospective analyses. We aimed to validate the utility of Large Language Models (LLMs) for scalable data abstraction and to identify prognostic histologic features from a large multi-institutional cohort. MethodsWe conducted a retrospective cohort study using data from six Childrens Oncology Group (COG) clinical trials. We utilized an LLM-based pipeline (OpenAI o3) to extract structured variables--including immunohistochemical (IHC) markers and CD99 staining patterns--from digitized, Optical Character Recognition (OCR)-processed pathology reports. Extraction accuracy was validated against a human-annotated ground truth (n=200) and cross-validated against senior experts (n=48). We assessed the association between extracted features and Overall Survival (OS) using Kaplan-Meier analysis and multivariable Cox proportional hazards regression, adjusting for metastatic status. FindingsWe analyzed 931 diagnostic pathology reports from 185 institutions spanning over 21-years. The LLM achieved a weighted average accuracy of 94% across 17 IHC markers; in a cross-validation subset, the LLM outperformed human annotators (weighted average accuracy over 15 IHC markers: LLM o3: 98.1%, a pediatric resident 91.4%, and a pediatric oncologist 95.9%). Survival analysis identified Neuron-Specific Enolase (NSE) and S100 as significant prognostic biomarkers. After adjusting for metastatic status, NSE positivity was associated with significantly inferior survival (HR 2.15, 95% CI 1.15-4.02, p=0.016); this risk was most pronounced in patients with non-metastatic disease (HR 5.64, p=0.0055). Conversely, S100 positivity was associated with improved survival (HR 0.58, 95% CI 0.34-1.00, p=0.046). InterpretationLLM-assisted extraction of pathology variables is highly accurate and scalable, capable of unlocking "dark data" from historical clinical trials. We identified NSE as a potent risk factor and S100 as a protective marker in Ewing sarcoma, particularly in localized disease. These findings suggest that AI-derived histologic data can refine risk stratification and, if validated, warrant inclusion in future prospective trials. Research in ContextO_ST_ABSEvidence before this studyC_ST_ABSWe searched PubMed and Google Scholar for articles published up to December 2025, using terms such as "Ewing sarcoma", "prognosis", "risk stratification", "large language models", "natural language processing", and "pathology report extraction". Current risk stratification for Ewing sarcoma relies predominantly on clinical variables, specifically the presence of metastatic disease and tumor size. While histologic heterogeneity is well-documented, it is rarely incorporated into risk models because extracting structured data from narrative pathology reports is labor-intensive. Small, single-institution studies have suggested potential prognostic roles for markers like Neuron-Specific Enolase (NSE) or S100, but results have been inconsistent and limited by small sample sizes. Furthermore, while Large Language Models (LLMs) have demonstrated potential for extracting clinical data, their application to "rescue" data from legacy, multi-institutional clinical trial documents (scanned PDF images) for rare disease biomarker discovery has not been validated at scale. Added value of this studyTo our knowledge, this is the largest study to utilize AI to extract histologic data from Ewing sarcoma pathology reports, aggregating 931 patients from six distinct Childrens Oncology Group (COG) clinical trials spanning over 21 years. We validated an LLM-based pipeline that converted noisy, optically character-recognized text from diverse institutions into structured data with 98.1% accuracy, outperforming human annotators. This scalable approach revealed that NSE positivity is a significant independent risk factor for mortality (HR=2.15), particularly in patients with non-metastatic disease where it confers a more than 5-fold increased risk of death. Conversely, we identified S100 positivity as a protective factor associated with improved survival (HR=0.58). Implications of all the available evidenceThis study demonstrates that LLMs can reliably unlock "dark data" from historical clinical trials, rendering vast archives of unstructured medical documents accessible for retrospective analysis. The identification of NSE and S100 as robust prognostic biomarkers suggests that these widely available immunohistochemical stains provide valuable information beyond standard diagnostic information. These findings support the integration of automated data extraction tools in research workflows and suggest that NSE and S100 status should be considered in the design of future risk-stratified clinical trials for Ewing sarcoma.

bioinformatics↗
bioRxiv2026

Skiver: Alignment-free Estimation of Sequencing Error Rates and Spectra using (k, v)-mer Sketches

BackgroundQuality control of sequencing datasets is an important first step in numerous bioinformatics pipelines such as mapping, variant calling, and assembly. Existing methods typically rely on alignment results or quality scores. However, the reference genome is not always available for mapping, and uncalibrated quality scores may yield biased estimates of error rates. ResultsWe present skiver, a reference-free and alignment-free algorithm that estimates sequencing error rates and calibrates Phred quality scores using (k, v)-mer sketches. By identifying the consensus from the sketched (k, v)-mers, skiver estimates survival and hazard rates that capture positional information of sequencing errors. Across simulated and real datasets from various sequencing platforms, skiver accurately recovers sequencing error rates and the proportion of different error types. We further demonstrate its ability to calibrate Phred scores. It also reliably handles complex datasets containing multiple strains, alleles, and repetitive regions through an iterative outlier filtering strategy. Skiver is computationally efficient and supports tools that need accurate sequencing error rate estimates or quality scores as prior knowledge. Availability and ImplementationAn implementation of skiver is available at https://github.com/GZHoffie/skiver, and dataset and scripts for reproducibility are available at https://github.com/GZHoffie/skiver-test.

bioinformatics↗
bioRxiv2025

DNA replication errors drive genome-wide small inverted triplication dynamics

Structural variants (SVs) have a profound impact on phenotype and diversity and are associated with human diseases. To explore the origination of SVs, we have analyzed 1,340 cancer genomes with annotation of 4,608 novel small inverted triplication (SIT) events and found that FEN1 is strongly associated with SIT incidence. Then, we performed long-read sequencing and developed PacBioR to annotate SITs in yeast FEN1 mutant cells. We found that SIT structures mimic classic inverted triplications but with a smaller DUP/IN/DUP structure of 184/160/184 bp on average, with a spacer sequence of 30 bp and breakpoint junction of 6 bp. We further showed that breakpoints of SITs preferentially occurred at nucleosome midpoints, aligned with Okazaki fragment termini, and those harbored in plasmids were precisely eliminated via DNA polymerase slippage over SIT-derived hairpin structures. This study provides mechanistic insight into SIT origination and offers practical tools for future studies on genome rearrangements.

genetics↗
bioRxiv2025

Structural mechanisms of pump assembly and drug transport in the AcrAB-TolC efflux system

Tripartite multidrug efflux pumps that span the cell envelope are essential for antibiotic resistance in Gram-negative bacteria. Here, we report cryo-EM structures of two endogenous efflux complexes from Escherichia coli: a TolC-YbjP subcomplex at 3.56 [A] resolution and the complete TolC-YbjP-AcrABZ pump at 3.39 [A]. Structural analysis reveals that YbjP, a previously uncharacterized lipoprotein, binds TolC in a 3:3 stoichiometry, bridging the TolC protomers at their equatorial domain. Clear density of the mature YbjPs N-terminal Cys19 indicates that YbjP is anchored to the outer membrane by an N-terminal lipid moiety. Notably, YbjP remains bound as TolC undergoes AcrA-induced opening, suggesting that this accessory protein accommodates the conformational change. The AcrB trimer simultaneously presents three distinct conformational states (L, T, O), capturing a complete transport cycle. These high-resolution structures provide insights into the architecture and mechanism of clinically relevant efflux machinery, identifying YbjP as a previously unrecognized structural component that contributes to TolC positioning and may assist in its membrane localization.

biophysics↗
bioRxiv2025

An ultra-long acting insulin enables glucose-synchronised release

Delayed and weak glucose-responsive kinetics, coupled with short plasma exposure and complicated formulation, remain major obstacles to the clinical translation of glucose-responsive insulin formulations. Here we report a rapidly absorbable, ultra-long acting, and glucose-responsive insulin analogue via engineering recombinant human insulin with two phenylboronic acids. The insulin analogue has a long circulating half-life (t1/2{beta} [~]150 h) due to its unique, unprecedented, glucose-responsive binding to blood circulation-associated proteins. This interaction drives the formation of a unique systemic reservoir that allows synchronised dynamic response in insulin levels to glucose fluctuations. In type 1 diabetic mice and minipigs, a single subcutaneous dose can maintain normoglycaemia for over one week (47.5-fold compared to insulin glargine). After the last injection of four consecutive weekly administrations in mice, the glucose-lowering effect can last 800 hours. Administering this glucose-responsive insulin analogue with a fully automated insulin delivery system can leverage dual closed loops and achieve a glucose time in range of over 85% and a coefficient of variation of approximately 30%, better than the recommended targets for human therapy. Importantly, no toxicity was identified in the study.

bioengineering↗
bioRxiv2025

Integrative Multi-omics Deciphers the Assembly Rules of the Human Skin Microbiome and Highlights Lipid-Mediated Niche Partitioning

Understanding the ecological assembly mechanisms of microbial communities is critical for deciphering host-microbiota interactions, however, such processes remain poorly characterized in cutaneous ecosystems. By profiling a non-industrialized rural cohort, this study deciphers the assembly rules governing the human skin microbiome and reveals an evolutionarily conserved core microbiota structured by niche selection. Microbial -diversity peaks when C. acnes and M. osloensis reach equilibrium, supporting the Intermediate Disturbance Hypothesis. Host lipids, rather than aqueous compounds, emerged as the primary drivers of microbial niche partitioning. We further demonstrate that C. acnes and Malassezia restricta function as core metabolic engineers, expressing diverse lipases that hydrolyze triglycerides (TGs) into free fatty acids (FFAs), thereby maintaining skin surface lipid homeostasis ([~]85% TG + FFA). Notably, virtually all skin surface FFAs are microbially derived and function as "public goods", enabling cross-feeding that supports auxotrophic members and fosters mutualistic interactions. Importantly, in vitro coculture experiments confirm that C. acnes establish a survival niche for M. restricta. Our findings support a paradigm shift from a taxonomic to a functional understanding of the skin ecosystem, underscoring microbial lipid metabolism as a central orchestrator of ecological stability and a promising target for therapeutic intervention. O_FIG O_LINKSMALLFIG WIDTH=182 HEIGHT=200 SRC="FIGDIR/small/674196v1_ufig1.gif" ALT="Figure 1"> View larger version (62K): org.highwire.dtl.DTLVardef@1274fa5org.highwire.dtl.DTLVardef@1ddfa07org.highwire.dtl.DTLVardef@49f917org.highwire.dtl.DTLVardef@807a14_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGRAPHIC ABSTRACTC_FLOATNO C_FIG

microbiology↗
bioRxiv2025

Efficient trace reconstruction in DNA storage systems using Bidirectional Beam Search

MotivationAs DNA data storage systems gain popularity, the need for an efficient trace reconstruction algorithm becomes increasingly important. These algorithms aim to reconstruct the original encoded sequence from its noisy sequenced copies (or "traces"), enabling a faster and more reliable decoding process. Previous works have often been adaptations of methods for multiple sequence alignment or read error correction, typically operating under strict assumptions such as fixed error rates. However, such methods demonstrate limited generalizability to real datasets with higher error rates and suffer from slow processing times when dealing with a large number of traces. ResultsWe propose a new probabilistic formulation of the trace reconstruction problem. Instead of optimizing alignment among traces, we model the traces as observations of a k-th order Markov chain and try to predict the sequence that is generated by the Markov chain with the highest probability. Such a formulation inspires a novel solution, i.e. Bidirectional Beam Search (BBS), whose reconstruction phase operates in linear time with respect to the length of the encoded sequences. Experiments on multiple public Nanopore datasets demonstrate that BBS achieves top-tier accuracy compared with the state-of-the-art methods while being [~]20x faster, showing its potential to enhance the efficiency of DNA data storage systems. Availability and ImplementationThe implementation of BBS is available at https://github.com/GZHoffie/bbs, and the dataset and scripts for reproducibility are available at https://github.com/GZHoffie/bbs-test.

bioinformatics↗