Biology subjects

Xu, X.

Publications and source records attributed to Xu, X..

At least 145 records · Page 8Linked to original sources

bioRxiv2025

Modulating inter-mitochondrial contacts to increase membrane potential for mitigating blue light damage

Mitochondrial membrane potential (MMP) is essential for mitochondrial functions, yet current methods for modulating MMP lack precise spatial and temporal control. Here, we present an optogenetic system that enables reversible formation of inter-mitochondrial contacts (mito-contacts) with high spatiotemporal precision. Blue light stimulation induces rapid formation of mito-contacts, which fully dissipate upon cessation of illumination. These light-induced mito-contacts can enhance MMP, leading to increased ATP production under stress conditions. Moreover, in human retinal cells and C. elegans, high MMP induced by mito-contacts alleviates the deleterious effects of prolonged blue light exposure, restoring energy metabolism and extending organismal lifespan. This optogenetic approach provides a powerful tool for modulating MMP and offers potential therapeutic applications for diseases linked to mitochondrial dysfunction.

biophysics↗

bioRxiv2025

AbTune: Layer-wise selective fine-tuning of protein language models for antibodies

AbstractO_ST_ABSMotivationC_ST_ABSAntibodies play central roles in immune defense and are widely used as therapeutic agents. However, the high structural and sequence diversity of antigen-binding loops, combined with limited experimental data and weak co-evolutionary signals, makes it difficult to develop generalizable predictive models. ResultsWe investigate test-time fine-tuning strategies to improve protein language model (pLM) performance in low-data settings, with a focus on antibody-related tasks. Systematic evaluations show that carefully constrained fine-tuning improves performance while preserving generalization. In particular, depth-selective fine-tuning consistently outperforms full-depth fine-tuning, with optimal performance achieved when tuning 50-75% of model layers for medium- to small-sized pLMs. We introduce AbTune, a test-time fine-tuning framework leveraging this depth-controlled adaptation strategy. Across antibody structure prediction, mutation effect prediction, and binding affinity prediction, AbTune outperforms standard pLM baselines and task-specific predictors on most benchmarks. We further analyze representation shifts, sequence-dependent adaptation behavior, and overfitting indicators, showing that fine-tuning depth, duration, and perplexity jointly determine performance. Availabilityhttps://github.com/haddocking/AbTune

bioinformatics↗

bioRxiv2025

The alternated brain states in resting state after immoral decisions

Studies have shown that the pattern of the brain in tasks can be effectively predicted from resting brain features. However, few studies explore how task could, in turn, influence resting state connectivity. This work attempts to understand this through the lens of immoral decisions. Using resting-state and task-state fMRI data collected before, during, and after an information-passing task involving dishonest choices with rewards, we employed the Hidden Markov Model (HMM) to capture the changes in the brain dynamics state. First, the HMM results identified 4 intrinsic brain states across both resting scans and task scans, including one reward network (state 1) and one control network (state 3). The reward network are associated with high dishonesty, while the control network are associated with low dishonesty. Importantly, task engagement in immoral behavior altered the post-task brain state. As participants engaged in persistent dishonesty, the network reconfigures itself to priorities the reward network and suppress the control network. Such suppression persists beyond the immediate task timeframe and leaves lingering signatures in the post-task resting scan. Contrary to the view of resting-state as a static baseline, our analysis showed the "non-resting" nature of post-task resting scans, where dishonesty could have an "after-effect" on neural dynamics. Together, these findings suggest that the post-moral decision brain operates not as a static system but as a set of dynamically shifting states, whose adaptive trajectories may underlie the lasting effect of decision behavior in the prior task.

neuroscience↗

bioRxiv2025

A Population-scale Single-cell Spatial Transcriptomic Atlas of the Human Cortex

The genetic and spatial determinants of cell type diversity in human cerebral cortices remain poorly defined. Here, we present a population-level single-cell spatial transcriptomic atlas of human cortices from 71 donors across the lifespan. We identified 906 layer-specific genes showing conserved and divergent laminar expression patterns between humans and other species. Spatial analysis revealed neuronal vulnerability and glial activation during aging, together with a decline in the proportion of superficial SST neurons and their interactions with other cells. Disease-associated genes exhibited high cell-type and layer-specific expression, implicating the pathogenic role of spatially specific gene expression. Spatial cis-eQTL analysis identified regulatory variants linked to genes related to diseases like Tourette syndrome. Cross-species comparison demonstrated glial expansion in the human cortex, accompanied by enhanced neuron-glia communication via the neuregulin signaling. Together, we provide a comprehensive single-cell atlas of the human cortex that is essential for understanding aging, evolution, and disease pathogenesis.

neuroscience↗

bioRxiv2025

scRetinaDB: A Comprehensive Database of Single-Cell and Spatial Omics from Cross-Species Retinas

The retina is essential for encoding visual signals, and its dysregulation can lead to retinal diseases. Recent advances in single-cell and spatial sequencing technologies have yielded extensive omics data from retinal tissues across species and biological conditions. However, existing retinal omics data are dispersed across various repositories without uniform processing, which limits integrative analysis. To address this we developed scRetinaDB (https://casapp.dnayun.com/scretina/), a comprehensive resource that aggregates single-cell RNA sequencing (scRNA-seq), single-cell assay for transposase-accessible chromatin using sequencing (scATAC-seq), and spatial RNA sequencing (spRNA-seq) data from retinas across species and diverse biological conditions. The database comprises over 2.79 million retinal cells collected from 453 scRNA-seq datasets spanning 34 studies, 17 species and 27 biological conditions. For each species, these scRNA-seq datasets were integrated to construct a retinal cell atlas. In addition, scRetinaDB also contains 107 scATAC-seq and 18 spRNA-seq datasets from human and mouse retinas. The scRetinaDB website provides four major modules separately for browsing species-specific omics data, searching cross-species omics profiles, performing analyses of cell type annotation and cell similarity analysis, and downloading preprocessed multi-omics datasets. Overall, scRetinaDB is a valuable resource for retinal single-cell and spatial omics, advancing cross-species studies particularly in vision research.

bioinformatics↗

bioRxiv2025

An antifungal with a novel mechanism of action discovered via resistance gene-guided genome mining

Invasive fungal infections claim over two million lives annually, a problem exacerbated by rising resistance to current antifungal treatments and an increasing population of immunocompromised individuals. Despite this, antifungal drug development has stagnated, with few novel agents and fewer novel targets explored in recent decades. Here, we validate acetolactate synthase (ALS), an enzyme critical for branched-chain amino acid biosynthesis and absent in humans, as a promising target for new therapeutics. Using resistance gene-guided genome mining, we discovered a biosynthetic gene cluster in Aspergillus terreus encoding HB-35018 (1), a novel spiro-cis-decalin tetramic acid that potently inhibits ALS. Biochemical and antifungal assays demonstrate that 1 surpasses existing ALS inhibitors in efficacy against Aspergillus fumigatus and other pathogenic fungi. Structural studies via cryo-electron microscopy reveal a unique covalent binding interaction between compound 1 and ALS, distinct from known inhibitors and finally, we demonstrate that ALS is essential for the virulence in a mouse model of invasive aspergillosis. These findings position ALS as a promising target for antifungal development and demonstrate the potential of resistance gene-guided genome mining for antifungal discovery.

bioengineering↗

bioRxiv2025

Distinct cell wall molecular architecture of dimorphic Talaromyces marneffei cells revealed by solid-state NMR spectroscopy

Talaromyces marneffei, causing systemic infections in immunocompromised patients ranging from HIV/AIDS individuals to cancer and transplant recipients, is an increasingly urgent global pathogen. However, the fungus remains underrecognized despite the systemic infection disease talaromycosis caused by this pathogen is associated with high mortality rates. Its pathogenicity depends on a temperature-triggered shift from saprophytic mold (25 {degrees}C) to pathogenic yeast (37 {degrees}C), and the two growth forms display distinct sensitivity to antifungal drugs, which processes involve extensive cell wall structure and components remodeling. To dissect these processes, we use solid-state nuclear magnetic resonance (ssNMR) and other techniques to show that T. marneffei yeast and hyphal cells have distinct cell wall thickness and hydrophobicity, and different assembly of mobile and rigid polymers within the T. marneffei cell wall. The yeast wall was 2.3 times thicker and more hydrated. ssNMR revealed a rigid core of {beta}-1,3-glucans, chitin and chitosan, with {beta}-1,3-glucan rising from 57% in mold to 72% in yeast. Both forms showed tight polysaccharide packing, but only mold exhibited lysine-containing protein interactions with chitin and chitosan. These insights not only map the structural basis of host temperature adaptation and also inform targeted antifungal design in future.

bioinformatics↗

bioRxiv2025

NPAS2 attenuates VSMC phenotypic switching in ascending thoracic aortic aneurysm via LPCAT3/PC-PUFA2S-mediated ferroptosis

Ascending thoracic aortic aneurysm (ATAA) is a life-threatening disorder with limited therapeutic options, critically linked to vascular smooth muscle cell (VSMC) phenotypic switching. Neuronal PAS Domain Protein 2 (NPAS2), a circadian rhythm-related transcription factor, regulates diverse physiological processes. However, the biological functions and underlying regulatory mechanisms of NPAS2 in VSMCs during ATAA pathogenesis remain to be elucidated. NPAS2 expression decreased in ATAA patients, PDGF-BB-treated HASMCs and BAPN-administrated mice. NPAS2 depletion facilitated VSMC phenotype switching. VSMC-specific NPAS2 knockout (NPAS2SMKO) mice exhibited aggravated ATAA. Mechanistically, NPAS2 depletion attenuates its transcriptional repression of LPCAT3, subsequently elevating the accumulation of phosphatidylcholines with two polyunsaturated fatty acyl chains (PC-PUFA2S), thereby promoting ferroptosis-induced VSMC phenotype switching and accelerating ATAA progression. Targeting NPAS2 represents a potential therapeutic strategy for ATAA treatment.

molecular biology↗

bioRxiv2025

Establishing a continuum of cell types in the visual cortex

The mammalian cerebral cortex is composed of neurons whose properties vary in a continuous fashion rather than falling into discrete cell types. In the mouse visual cortex, excitatory neurons in layer 2 and 3 (L2/3) form such a continuum along cortical depth, patterned by the graded expression of hundreds of genes. Here we sought to understand how this continuum develops and contributes to cortical wiring. Using single-nucleus multiomics (RNA- and ATAC-Seq) and spatial transcriptomics, we show that the L2/3 continuum is established in two phases. During the first postnatal week, a genetically hardwired program establishes a primitive continuum of cell identities spanning the depth of L2/3. The second program, promoted by visual experience, is later superimposed upon the preexisting continuum. This second phase is driven by activity-regulated transcription factors that drive the L2/3 depth-dependent expression of genes linked to synaptic function and plasticity. We show that neurons at different positions along the L2/3 continuum project preferentially to distinct higher visual areas and that visual deprivation disrupts targeting to some higher visual areas while sparing others. Thus, cortical continua emerge through a stepwise process in which genetic programs and sensory experience specify neuronal identity and sculpt intracortical wiring specificity.

neuroscience↗

bioRxiv2025

Successive cultivation under drought selects for specific microbiome members in the wheat rhizosphere

Growing knowledge on plant microbiomes demonstrates the contribution of the host plant during microbiome assembly, especially under stress conditions commonly threatening crops. To dissect the influence of a plant on its microbiome, repeated cycling of microbiomes can be utilized to enhance functional properties in the enriched microbial communities. We used such a successive cultivation approach for wheat (Triticum aestivum) microbiome under drought conditions and selected lineages for drought resilience and susceptibility, with and without enriching the starting community with a wheat isolate library. Significant differences in the rhizosphere microbiome between selection regimes were confirmed through 16S rRNA gene amplicon sequencing. Notably, replicate lineages of each selection regime showed convergence to similar microbiomes. Specific genera were abundant depending on the selection regimes; Stenotrophomonas under drought resilience, while Rahnella under drought conditions when the strain library was added initially. Applying Stenotrophomonas or Rahnella as single inoculum did not improve drought resilience in wheat. We hypothesize that complex microbiome dynamics take place during successive cultivation, which underscores the importance of considering complex plant-microbiome systems for studying plant stress resilience. Successive cultivation remains a valuable approach for observing rhizosphere microbiome changes under different conditions.

microbiology↗

bioRxiv2025

Embryonic Atrial Injury Programs an Anti-Fibrotic Atrial Fibrillation Substrate

Atrial myopathy is associated with atrial fibrillation in adults, yet the role of embryonic atrial injury in predisposing individuals to atrial fibrillation remains unclear. Using an inducible, cardiomyocyte-specific diphtheria toxin A-mediated injury mouse model, we found that injured embryonic atria exhibited upregulation of apoptosis and TNF signaling pathways, alongside downregulation of calcium handling and atrial fibrillation-associated genes. Single-cell RNA sequencing revealed two distinct cardiomyocyte populations with differential injury responses. Importantly, although myofibroblasts increased in the fibroblast population, these cells displayed an extracellular matrix gene expression profile distinct from the pro-fibrotic phenotype typically observed in fibrillating adult atria and showed no evidence of fibrosis. Concurrently, monocytes/macrophages were activated and showed upregulated expression of the anti-fibrotic factor GPNMB. These findings suggest that adaptive tissue remodeling is counterintuitively prevented from progressing to fibrosis, potentially through GPNMB-mediated mechanisms. This study elucidates molecular pathways linking developmental atrial injury to myopathy and proposes novel strategies to attenuate atrial fibrillation progression.

pathology↗

bioRxiv2025

Resolving cDC2 heterogeneity across human cancer atlases

Dendritic cells (DCs) are vital in driving effective anti-tumour immune responses. Multiple DC subpopulations have been identified in human tumours, however their alignment, phenotype and function across tumour types have not been comprehensively addressed. Here, we curated single-cell RNA sequencing datasets to generate an extensive integrated atlas of myeloid antigen presenting cells (APCs) across different human cancer types. We confirm that cDC1, cDC2 and mregDC represent the major DC populations present in human tumours, and that these populations are highly conserved regardless of cancer type. A distinct DC3 population was not identified within the atlas, suggesting these cells are less distinguishable in tumour tissue. The cDC2 compartment resolved into two subpopulations, a minor population that aligned tumour associated CD207+CD1A+ cDC2 with splenic cDC2A, and a predominate subset aligning with cDC2B. This integrated atlas serves as a powerful resource enabling deeper investigation into the functions of tumour-associated DC diversity, phenotype and function, across a range of human cancer types.

immunology↗

bioRxiv2025

The role of intrinsically disordered domains in regulating G protein coupled receptor signaling

The 2A adrenergic receptor (2AAR) is a clinically important target for various diseases including hypertension, diabetes and chronic pain. Here, using single-molecule fluorescence resonance energy transfer imaging, we show how agonist-specific activation dynamics in both structured transmembrane domain (TMD) and intrinsically disorders regions (IDRs) of 2AAR lead to diverse signaling profiles. Through seven pairs of strategically designed fluorophore labels, we systematically investigate the real-time conformational changes of 2AAR. Our study reveals unique TM6 dynamics in 2AAR, featured by a high energy barrier for agonist-induced outward movements essential for activation. In contrast, we identify agonist-specific conformational dynamics of a partially disordered extracellular loop (ECL2), highlighting its role as a dynamic regulatory module that controls receptor function. Moreover, we characterize the conformational landscapes of the long third intracellular loop (ICL3), revealing its compact structural features and membrane-proximal localization in the basal state, where it acts as a negative allosteric regulator in transducer coupling. Furthermore, we identify multiful functional sub-states of ICL3 that are dynamically modulated by both kinase phosphorylation and drug efficacy. These findings offer previously underappreciated structural and dynamic insights into 2AAR function governed by both TMD and IDRs, and may open up new avenues for the development of better therapeutics.

biophysics↗

bioRxiv2025

Claustrum-cortical reciprocal connections orchestrate allostatic responses following stress

Anxiety is an evolutionarily conserved response that supports threat detection and survival, yet dysregulated stress responses can drive its progression into pathological states. Here, we identify the claustrum (CLA) as a central hub that links acute stress responses to chronic affective dysfunction through cell-type-specific circuit dynamics. Acute social defeat stress robustly activated the CLA and induced anxiety-like behaviors in mice. Multimodal profiling revealed transcriptional and functional plasticity within CLA neurons, with Egr2-expressing excitatory and Gad2-expressing inhibitory populations exhibiting distinct adaptations to acute versus chronic stress. We further delineate a reciprocal CLA-anterior cingulate cortex (ACC) circuit that bidirectionally regulates stress responses in which glutamatergic CLAEgr2 [->] ACC projections promoted anxiety-like behaviors, whereas top-down ACC [->] CLAGad2inhibitory inputs constrained claustral output. Chronic stress induced hyperactivity in CLAGad2 inhibitory neurons and reshaped excitatory neuron dynamics, leading to increased intrinsic excitability, local circuit imbalance, and ultimately, depression-like phenotypes. These findings define a dynamic claustrum-centered circuit that governs the transition from adaptive anxiety to maladaptive affective states through balanced Egr2-Gad2 activity, and show that chronic-stress driven disruption of this excitatory-inhibitory equilibrium impairs stress coping and drives pathological behavioral outcomes. Graphic summaryAcute stress engages a claustrum (CLA)-centered network with activation of Egr2 excitatory neurons, promoting anxiety-like behaviors. Chronic stress drives CLAG142 neurons into a hyperactive state, enhancing local inhibition and suppressing excitatory output to induce depressive-like behaviors. A reciprocal CLAE7182[->]ACC feedforward and ACC[->]CLAG142 feedback circuit forms a state-dependent regulatory hub governing stress adaptation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=180 SRC="FIGDIR/small/673892v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@75d664org.highwire.dtl.DTLVardef@4e5c31org.highwire.dtl.DTLVardef@86b5f2org.highwire.dtl.DTLVardef@135045_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

The role of FRUITFULL controlling cell cycle during early flower development revealed by time series snRNA-seq experiments.

BACKGROUNDStarting from pools of undifferentiated cells, plants generate new organs post-embryonically in response to external and endogenous signals. This requires a dynamic coordination of cell division with cellular growth and differentiation regulatory programs. However, little is known how this coordination is achieved at the molecular level during flower development. RESULTSWe used time-series single-nucleus RNA sequencing (snRNA-seq) experiments of synchronized Arabidopsis thaliana flower developmental stages to characterize the transcriptome dynamics and the connections between cell cycle and developmental regulatory programs during early flower development. The results show a bifurcation between transcriptional trajectories corresponding to cell cycle progression and floral development. We identify the regulation of the cell cycle inhibitor KIP-RELATED PROTEIN 2 (KRP2) by FRUITFULL (FUL) as a key regulatory point on this bifurcation point, and validate the importance of this regulation in vivo. CONCLUSIONSOur work illustrates how time-series snRNA-seq experiments can be used to identify bifurcation points between regulatory programs and to identify candidate regulators on these bifurcations. In particular, we identify the regulation of KRP2 by FUL as an important regulatory point to balance cell division and developmental differentiation in plants.

plant biology↗

bioRxiv2025

Post-inhibitory rebound firing drives hypothalamic activation for male mating

Many behaviorally relevant limbic circuits are dominated by inhibitory connections, raising the question of how neuronal activation arises in such contexts. In male mating, both activation of mPOA and its inhibitory inputs are essential--a paradox previously ascribed to disinhibition. Here, we show that the mPOA largely lacks local inhibitory circuits, arguing against disinhibition. Instead, in vivo recordings reveal that mount-active mPOA neurons are suppressed prior to behavioral onset, and this inhibition negatively correlates with subsequent activation, consistent with post- inhibitory rebound firing (PIR). A biologically plausible conductance-based model demonstrates that synaptic inhibition interacts with T-type Ca{superscript 2} currents -- the ionic basis of PIR -- to promote mPOA neuron firing. Experimentally, bidirectional manipulations of mPOA T-type Ca{superscript 2} channels confirm this mechanism: knockdown reduces PIR and impairs male mating, while overexpression enhances mating. Together, these results identify PIR as a critical mechanism by which inhibition promotes activation in limbic circuits to drive male mating.

neuroscience↗

bioRxiv2025

A simple liquid 3D cell culture paradigm models oxidative mitochondrial metabolism of epithelial breast cancer cells with relevance for lung metastases.

Three-dimensional (3D) cell culture systems have emerged as powerful tools for modeling tumor biology in ex vivo settings. However, the diverse array of available 3D culture methods presents challenges in selecting the most appropriate model for specific research questions. This study provides a comparative analysis of breast cancer cells (SUM149, IBC-3, and MDA-MB-468) in the mammosphere culture (SphC) model or an "emboli" culture (EmC) model, which enrich for cancer stem cells and epithelial features, respectively. The EmC model, designed originally for inflammatory breast cancer, is characterized by media viscosity and mechanical rocking of the culture vessel. Notably, cells in EmC showed a distinct and durable reduction in cell proliferation ex vivo while demonstrating increased capacity to establish experimental lung metastases in vivo. Ultrastructural quantitative analysis of electron microscopy images suggested that cells in EmC acquire nuclear and mitochondrial features that resemble those of tumor tissue. Proteomics, single-cell transcriptomics, and metabolic flux analyses showed that cells in EmC and SphC favor mitochondrial oxidative metabolism (OXPHOS) and glycolysis, respectively. EmC rendered cells hypersensitive to OXPHOS inhibition, but more resistant to oxidative stress. Several genes associated with lung metastasis, including ID1, were specifically enriched in EmC. Given the emerging role of OXPHOS in cancer cell survival during dissemination and as established metastases, we propose that the EmC paradigm is a suitable ex vivo model to study signaling pathways relevant for tumor tissue and to assess drug sensitivities and resistance mechanisms of metastatic breast cancer cells ex vivo. SIGNIFICANCEThis study provides an in-depth characterization of a resource-efficient yet powerful 3D culture paradigm to improve the physiological relevance of ex vivo approaches. Applicable to epithelial cancers, this model offers a platform to accelerate the discovery of physiologically relevant signaling pathways and specific cancer cell vulnerabilities.

cancer biology↗

bioRxiv2025

An integrated multi-tissue atlas of epigenomic landscapes and regulatory elements in the bovine genome

Deciphering the regulatory syntax of the genome is essential to understand the genetic and molecular architecture of complex traits, as most trait-associated variants lie in non-coding regions. Yet, functional annotation of the bovine genome remains limited, hindering our ability to unravel the mechanisms underpinning complex traits of economic and ecological importance in cattle. Here, we present a comprehensive epigenetic atlas comprising 1,138 genome-wide epigenetic profiles, including chromatin accessibility, six histone modifications, CCCTC-binding factor (CTCF) transcription factor binding, DNA methylation, chromatin conformation, and transcriptomes across 53 adult tissues, five fetal tissues, and seven primary cell types. This atlas-level data enables us to annotate around 45% of the genome as putative regulatory elements exhibiting tissue- or cell-specific regulatory activity. Leveraging sequence-to-function deep learning models, we discovered 301 sequence motifs and predicted the functional impact of genetic variants through in silico mutagenesis, thereby facilitating the decoding of the regulatory syntax of the cattle genome and fine-mapping of GWAS loci for 22 complex traits. Cross-species analysis further revealed evolutionarily conserved features of regulatory architecture and provided evolutionary insights into complex traits and diseases in humans. Together, this atlas offers a foundational resource for advancing cattle functional genomics, sustainable breeding, and studies of regulatory evolution.

genomics↗