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Zhang, C.

Publications and source records attributed to Zhang, C..

At least 73 records · Page 4Linked to original sources

Beyond infinite sites: Generalized ABBA-BABA statistic for deeper phylogenies

The Pattersons D statistic detects gene flow from ABBA-BABA site patterns, but its biallelic site patterns fail under deeper divergences where multiple hits cause false positives. We propose two extensions, D+ and D*. Both incorporate multiallelic site patterns to reduce saturation bias under JC and F84 model. Simulations show that D+ and D* both remain correctly null under all conditions and detect gene flow effectively, with distinct advantages: D+ guarantees non-negativity of the denominator, while D* provides greater robustness when mutation rates vary across genomic regions. The source code and binary files are publicly available at https://github.com/chaoszhang/ASTER.

bioinformatics↗

Saturated mutagenesis screen of M-MLV reverse transcriptase identifies variants enhancing prime editing efficiency

Prime editing enables the precise modification of genomes, thereby holding great potential for the treatment of genetic diseases. Despite substantial advancements in prime editing technology and the initiation of the first clinical trial for treating chronic granulomatous disease, further enhancement of editing efficiency across edit types is still urgently needed. Here, we developed a compact prime editor, PE2{Delta}R, by deleting the RNase H domain of the MMLV reverse transcriptase (MMLV-RT). We then conducted a saturated mutagenesis screen targeting two DNA interacting regions within the PE2{Delta}R-RT Fingers domain. By integrating three highly effective mutations (I61R, V101R, S67W) into PEmax lacking RNase H domain (termed PEmax{Delta}RM3), we achieved up to a 90% increase in editing efficiency across editing types compared to PEmax. Structural modelling using AlphaFold 3 suggests that these mutations enhance primer-template stabilization and guide the RNA/DNA hybrid into a catalytically favourable trajectory, providing a mechanistic explanation for the enhanced activity. Taken together, our study demonstrates proof-of-concept for the application of unbiased mutagenesis screen to identify novel mutations that enhance prime editor performance. Furthermore, we discovered that RT variants (I61R, V101R, S67W) synergize with PEmax and epegRNA to improve prime editing efficiency across edit types, with the strongest improvement observed in introducing small deletions.

molecular biology↗

Folding scFv--Antigen Complexes at Scale

AO_SCPLOWBSTRACTC_SCPLOWAccurate modeling of antibody-antigen (Ab-Ag) complexes is central to biologic development, yet the reliability and failures of modern Ab-Ag folding pipelines remain poorly characterized. Single-chain variable fragments (scFvs) are thera-peutically important antibodies, but large-scale evaluations of structure prediction models on scFv-Ag complexes are largely lacking. We introduce a scalable bench-marking pipeline that generates large ensembles of scFv-Ag structure predictions by cofolding a curated subset of 3,800 Ab-Ag complexes from SAbDab using multiple state-of-the-art models under diverse inference-time settings. The resulting dataset, SCALE (scFv-Ag CompLex Ensembles), includes standardized scFv-Ag sequences and around 200,000 predicted complexes spanning different models, sampling strategies, and auxiliary inputs. Using SCALE, we evaluate model performance in recovering correct scFv-Ag interfaces and assess the ability of existing confidence metrics to select the best structure from prediction ensembles. We find that while confidence scores effectively distinguish easy from hard scFv-Ag complexes, they often fail to identify the highest-quality interface for a given target. Further analysis shows that near-correct interfaces typically appear in ensembles but at low frequency, and inference-time choices such as sampling, recycling, and using evolutionary or structural information are crucial for accurate scFv-Ag complex predictions. Dataset and analysis code are available at https://huggingface.co/datasets/ravishah1/SCALE

bioinformatics↗

Pathogen context reshapes antimicrobial peptide generation

Antimicrobial peptides are a promising source of new anti-infective agents, but their discovery is limited by a practical bottleneck: selecting a small set of candidates to synthesize and test for a specific pathogen. Existing peptide generators can expand antimicrobial-like sequence space, but most leave pathogen specificity to predictors or filters after generation. Here, we use AMPHORA, a pathogen-conditioned sequence-structure generator, to build antimicrobial peptide libraries shaped by target context. AMPHORA couples a short-peptide representation model to latent-flow generation conditioned on target class, genome-derived features and strain-description text. In matched, partial and shuffled controls, pathogen context redirected generated peptide pools beyond broad activity labels, with the strongest effects when genome and text conditions were combined. Counterfactual generation from the same initial noise showed that strain descriptions primarily changed amino-acid choices, whereas genome-derived features contributed more strongly to predicted structural properties. Across species, AMPHORA produced target-dependent enrichment, and matched bacterial context shifted APEX-predicted potency-score distributions compared with class-only generation. The generated peptides remained diverse, novel and peptide-like by sequence and predicted-structure analyses. Collectively, our results establish pathogen context as an active design signal for antimicrobial peptide generation and provide a target-aware route to pre-synthesis library design.

bioinformatics↗

Lineage-Specific Neofunctionalization of Polyacetylene-Directing UGT76 Glycosyltransferases in Campanulaceae

Polyacetylene glycosides exhibit notable pharmacological activities, yet the glycosyltransferases acting on their polyacetylene scaffolds remain unknown. Here we report a telomere-to-telomere genome assembly of Codonopsis pilosula and, guided by spatial metabolomics, characterize three UDP-glycosyltransferases: CpUGT76BG1 and CpUGT76BG2 catalyze the direct glycosylation of lobetyol to lobetyolin, while CpUGT94BY2 performs subsequent sugar-sugar coupling to produce lobetyolinin, with each activity confirmed by in planta overexpression. Structural modeling reveals that CpUGT76BG1 and CpUGT76BG2 employ a deep hydrophobic tunnel to fully encase the linear polyacetylene chain, a binding architecture distinct from the shallow pockets used by canonical plant UGTs for planar aromatic substrates. Ancestral sequence reconstruction across eleven nodes partitions the UGT76 lineage into three functionally distinct evolutionary stages, tracing the trajectory from an ancestral shallow pocket to this specialized deep architecture. These findings establish the key glycosylation steps of polyacetylene glycoside biosynthesis, define a tunnel-based paradigm for non-planar substrate recognition, and reveal how tandem duplication-driven active site remodeling generates metabolic novelty.

evolutionary biology↗

Constrained body mass evolution and decoupled morphological rates in plesiosaurs

Body size, through its links to various physiological traits, has often been hypothesized to influence evolutionary rates. Negative body size-rate correlations have been reported in the morpho-logical or molecular evolution of several extant vertebrate groups, including mammals, birds, reptiles, and teleost fishes. In this study, we estimated body masses for 89 species of plesiosaurs, a clade of Mesozoic aquatic reptiles, and found that their body size evolution conforms to a three-regime Ornstein-Uhlenbeck process, indicative of constrained evolution. Rates of morphological evolution, inferred using the skyline fossilized birth-death process and the variable-rates model, show minimal support for a correlation with body size in this clade. Our results thus serve as a counterexample, suggesting that the negative body size-rate relationship is not a universal vertebrate pattern, but rather a trend restricted to certain lineages.

paleontology↗

A brain-tumour axis links chronic stress to gastric cancer progression through NPY signalling

Chronic stress promotes gastric tumour growth, but the central neural pathways remain largely enigmatic. Here, we identify a brain-tumour axis, implicating the central amygdala (CeA) activity in promoting gastric cancer growth through sympathetic neuropeptide Y (NPY) signalling occurring within the tumour. Using clinical datasets, patient samples, pathway tracing, electrophysiology and chemogenetic manipulation, we demonstrate that stress selectively increases NPY Y1 receptor (NPY1R) synthesis in the patients gastric cancer tissue; moreover, the NPY1R density correlates with advanced cancer stage and poor prognosis. In mice, daily constraint chronic stress enhances CeA excitability and promotes sympathetic neurotransmitter norepinephrine release within the tumour microenvironment. Norepinephrine, in turn, increases tumour endogenous NPY/NPY1R production and the activation of downstream MAPK/Erk1/2 signalling pathway, which drives cancer cell proliferation and invasion. Manipulating CeA neuronal activity alone can regulate tumour growth, whereas selectively blocking tumour NPY1R prevents stress-induced tumour progression in vivo and cancer cell migration in vitro. This study identifies a central-to-peripheral circuit linking chronic stress to gastric cancer growth, and highlights NPY1R as a potential therapeutic target.

Cancer Biology↗

Scalable Plasmonic Metasurface-Enabled Physics-Guided Self-Supervised Cellular Imaging

High-quality cellular imaging, especially in live cells, remains constrained by the trade-off among signal-to-noise ratio, phototoxicity, and instrumentation complexity. Here, we report a scalable plasmonic metasurface that generates a spatially ordered array of fluorescence-enhancing near-field hotspots and enables self-supervised denoised, cellular imaging with improved feature readability on a conventional wide-field microscope. The registered hotspot lattice serves as a physics-derived functional prior that identifies where fluorescence amplification is physically grounded and steers neural-network training accordingly, reducing reliance on paired ground truth, large external pretrained models, or extensive supervised datasets. We demonstrate two labeling-density-dependent operating regimes: dense labeling for cytoskeleton structural imaging and sparse labeling for multiplexed sensing of plasma-membrane-associated dynamics across the hotspot array. Our work unites scalable nanophotonic hardware and self-supervised computational imaging into a practical platform for structural bioimaging and on-chip live-cell biosensing under simple wide-field imaging conditions.

biophysics↗

Active non-redundancy and viral orchestration sustain diel microbial successions in the coastal ocean

Ecosystem resilience in dynamic coastal oceans is conventionally ascribed to functional redundancy, where taxonomically distinct microbes buffer environmental fluctuations through interchangeable metabolic roles. In this study, we reveal a deterministic succession architecture sustained by active non redundancy and temporal metabolic coupling, uncovered via autonomous drone array metatranscriptomic sampling in Daya Bay, China. By resolving the transcriptional landscape into six chronometrically phased modules rather than simple time points, we demonstrate a near total renewal of the active gene pool, with greater than 90% of transcribed clusters showing phase exclusivity within approximatively a two-hour window. This radical functional reshaping exposes a tight, scale dependent taxonomic functional coupling where community composition is a strong, linear predictor of metabolic output, peaking at the genus level (p < 0.0001). Functional continuity is maintained not by redundant generalists, but by a precisely sequential relay of specialists, each optimized for transient microniches with minimal overlap between successive phases. Deep learning structural adjudication of the psbA gene pool further reveals viral orchestration of this temporal coupling, where incoming cyanophages introduce structurally distinct protein variants that sustain photosynthetic electron flow under peak irradiance. These findings redefine coastal microbiome stability as a fine-tuned rapid succession of temporal specialists rather than a redundant backdrop. We propose a fundamental revision of marine ecosystem models, shifting from passive buffering frameworks to deterministic, clock driven architectures, which may prove to be critical for forecasting microbiome responses to accelerating short term climate variability.

microbiology↗

RNAStabFormer: Region-Aware Multi-Task Hybrid Learning for RNA Stability Prediction from Pulse-Chase Transcriptomics

RNA stability is a major post-transcriptional regulator of gene expression, yet sequence-based prediction from pulsechase transcriptomics remains difficult because labels depend on time window, quantification region, and replicate quality. We present RNAStabFormer, a controlled RNA stability framework centered on a Region-aware Multi-task Hybrid Transformer (RAMHT). RAMHT encodes 5'UTR, CDS, and 3'UTR nucleotide context, adds a CDS codon stream, upgrades engineered sequence features into a tabular interaction branch, and uses gated multi-task regression to predict four ENCODE BrU-seq/BruChase-seq stability proxies, with exon total 6 h/0 h as the primary task. Across 26 outer splits including 23 chromosome holdouts, a heterogeneous three-member RAMHT ensemble achieves 0.773 mean Pearson correlation on the primary task, statistically matching an engineered-feature XGBoost baseline (0.773; mean paired delta +0.000004; bootstrap 95% CI [- 0.003845, +0.004077]; Wilcoxon p = 0.8613). The ensemble improves over the strongest single RAMHT member (0.768 to 0.773; 23/26 split wins), while a strict nested XGBoost+RAMHT blend reaches 0.775. Same-split checks also exceed frozen full-length mRNA-LM embeddings (0.760) and public LAMAR-DR transfer (0.180). Gate, ablation, and recoding analyses show that engineered sequence grammar remains dominant, while nucleotide and codon branches provide complementary CDS-local signal. RNAStabFormer narrows the gap between neural RNA sequence modeling and strong tabular baselines while retaining an extensible architecture for interpretation and biological integration.

bioinformatics↗

The atypical IκB factor IκBδ enhances CD8 T cell accumulation and effector functions in solid tumors

Two prominent mechanisms by which tumors fend off immune control are by constraining the ability of T cells and CAR T cells to survive and expand in the tumor, and by restraining their ability to sustain full cytotoxic capacity. We identified I{kappa}B{delta}, encoded by Nfkbid, a poorly characterized I{kappa}B family member, as a molecular lever that overcomes both of these constraints on anti-tumor CD8+ tumor-infiltrating lymphocytes (TILs). Nfkbid is an NFAT target gene that is expressed in CD8+ effector T cells and, at modest levels, in CD8+ TILs. We found that Nfkbid depletion impaired TIL accumulation, exacerbating the growth of solid tumors. On the other hand, ectopic I{kappa}B{delta} overexpression enhanced TIL expansion, reduced the expression of exhaustion-associated transcription factors and inhibitory receptors, and elevated cytotoxic molecule production, leading to enhanced tumor control. I{kappa}B{delta} has a shorter protein isoform that is identical in a core region spanning the ankyrin-repeat domain known to interact with NF{kappa}B proteins, but that lacks the [~]150-residue N-terminal region. We showed that the shared core region is sufficient to drive T cell accumulation, whereas the N-terminal peptide region is required for robust effector function and to counter exhaustion, underscoring that tumor-infiltrating CD8+ T cell accumulation and effector differentiation are separable programs. Our current study provides evidence that I{kappa}B{delta}, an atypical member of the NF{kappa}B family, is a lever to overcome two cardinal deficits that limit CD8+ TIL anti-tumor efficacy: impaired accumulation in the tumor and diminished effector function.

immunology↗

Integrative multi-omic analysis identifies tumor-intrinsic p38 as a driver of immune exclusion in human epithelial cancers

Patients with tumors not responding to immune-checkpoint inhibition (ICI) often harbor a non-T cell-inflamed tumor microenvironment, characterized by the absence of IFN-{gamma}-associated CD8+ T cells and dendritic cell activation. While the role of p38 mitogen-activated protein kinases (MAPKs) in regulating dendritic and myeloid cells is established, the tumor-intrinsic immunomodulatory function of p38 remains underexplored. Here, we identify tumor cell-intrinsic p38 signaling as a target candidate associated with immune exclusion and reduced immunotherapy response. In human papillomavirus-negative head and neck squamous carcinoma (HNSCC), molecular analysis of 395 tumor tissues revealed a p38-centered network enriched in non-T cell-inflamed tumors. Multi-cancer single-cell RNA sequencing analysis of over 200,000 cells further identifies p38 activation as a potential immune-exclusion program across multiple epithelial tumor types, including HNSCC and lung squamous cell carcinoma (LUSC), supported by tissue validation in [~]250 human biospecimens using multispectral imaging and digital spatial profiling. Functional studies demonstrate that p38 knockdown or pharmacologic inhibition in HNSCC and LUSC cell lines increases T cell migration, with CXCL16 identified as a chemokine mediator in vitro; neutralization of CXCL16 attenuated this effect. Together, these findings identify tumor-intrinsic p38 activation as a driver of immune exclusion in epithelial cancers and support its potential as a therapeutic target to overcome immunotherapy resistance.

Cancer Biology↗

Coordinated regulation of Barrier-to-Autointegration Factor (BAF) phosphorylation by protein phosphatases PP2A and PP4

Phosphorylation is crucial for the regulation of Barrier-to-Autointegration Factor (BAF), a conserved nuclear envelope (NE)-associated protein that, among its diverse functions, binds chromatin and mediates its anchoring to the NE. In interphase, cycles of BAF phosphorylation, which inhibits chromatin binding, and dephosphorylation, which restores it, are essential for the dynamic anchoring of chromatin to the NE. During mitosis, BAF becomes highly phosphorylated and dissociates from chromatin, except for a small centromeric pool (cenBAF). Upon mitotic exit, BAF is dephosphorylated and re-associates with chromosomes. Two Ser/Thr protein phosphatases, PP2A and PP4, are known to dephosphorylate BAF, but their specific roles in regulating BAF phosphorylation are not yet fully understood. Here, we show that PP2A is the main phosphatase driving BAF dephosphorylation in interphase, whereas PP4 plays a minor role. During mitosis, both PP2A and PP4 localize to centromeres; however, only PP4 directly interacts with cenBAF, suggesting that it maintains this fraction in an unphosphorylated state. Notably, PP4s centromeric localization depends on PP2A. At mitotic exit, PP2A dephosphorylates the large pool of mitotically phosphorylated BAF, while PP4 controls the timing of its re-association with chromatin. Together, these findings reveal a coordinated interplay between PP2A and PP4 in controlling BAF dephosphorylation and function.

Molecular Biology↗

Whole-proteome structure/function prediction in Uropathogenic E. coli reveals previously missed host-microbe and microbe-phage interaction pathways

The rapid advancement of high-throughput sequencing technologies has vastly increased the number of known protein sequences, but the experimental characterization of their structures and functions lags behind. This gap in knowledge impedes our understanding of biological mechanisms of these proteins, hinders the interpretation of high-throughput experiments, and exposes a significant challenge in modern biology: deducing the structural and functional information of proteins based on their sequences. Most computational approaches rely on homology with well-annotated proteins, yet many proteins lack identifiable homologues, reducing the power of this approach. Here, we integrated cutting-edge protein structure and function prediction methods to develop a complete sequence-structure-function pipeline that predicts structures and functions based on primary sequences. We applied this pipeline to predict the structure and function of all proteins in Escherichia coli UTI89, a model strain of uropathogenic E. coli. Based on the predicted functions, we performed enrichment analysis on the whole genome and revealed the possible roles and related biological mechanisms of poorly annotated proteins in this organism. Moreover, the performance of our pipeline was further validated through detailed case studies of the UTI89_C0931 and ybtS genes. Finally, we compiled the UTI89 structure and function database (https://seq2fun.dcmb.med.umich.edu/UTI89), offering it as a community resource to aid researchers in elucidating the roles of unannotated proteins in uropathogenic E. coli. This database aims to bridge critical knowledge gaps in microbial pathogenicity and resistance, enhancing our capacity to tackle emerging health threats.

microbiology↗

ANCHOR: haplotype-aware allelic and isoform inference from single-cell long-read RNA sequencing with de novo variant calling

Long-read RNA sequencing enables haplotype- and isoform-resolved allelic analysis of transcriptomes, yet extending this capability to single cells and distinct cell types remains computationally challenging due to sparse coverage, sequencing errors, incomplete variant information, and reference-biased transcript assignment. Here we present ANCHOR, a haplotype-aware framework for single-cell long-read RNA sequencing that performs de novo expressed-variant discovery, molecule-level haplotype assignment and isoform-resolved allelic quantification. ANCHOR combines a signed-graph variant caller, pair hidden Markov modelling and beta-binomial UMI aggregation to infer parental allele counts for genes and splice-resolved isoforms, without requiring a pre-existing phased genotype or deep learning. In human single-cell long-read RNA benchmarks, ANCHOR improved variant-calling performance over tested long-read RNA callers at single-cell and low-to-moderate coverage, and its beta-binomial model reduced depth-driven false positives in allele-specific expression testing. Applied to newly generated single-cell long-read RNA-seq data from reciprocal mouse crosses during gastrulation, ANCHOR resolved cell-type- and isoform-specific parent-of-origin imprinting and identified an antagonistic maternally biased Sgce isoform. ANCHOR provides a general framework for allele-and isoform-resolved analysis of diploid single-cell long-read transcriptomes.

bioinformatics↗

Conformational changes underlying electromechanical transduction in prestin resemble a transport transition in pendrin

Prestin (SLC26A5), a membrane protein in cochlear outer hair cells, drives electromechanical transduction essential for mammalian hearing. Unlike other SLC26 anion transporters, prestin functions as a voltage-dependent molecular motor, transitioning between contracted and expanded conformations. How this transition relates to the transporter cycle of SLC26 family members remains unclear. Here, multi-microsecond molecular dynamics (MD) simulations starting from a contracted conformation reveal a rapid, spontaneous transition to an expanded state that resembles the inward-facing conformation of the anion exchanger pendrin (SLC26A4 from mouse). An accompanying transmembrane area expansion is localized to the inner membrane leaflet. In line with this observation, reduced unitary sensor charge movement accompanies neutralization of charged residues localized near the inner leaflet. Simulations uncover a previously uncharacterized contracted conformation that resembles outward-facing pendrin; the MD also predicts an extracellular anion-binding site in prestin. A 3.27-[A] resolution cryo-electron microscopy structure of prestin in the presence of thiocyanate anions confirms this site, which appears to be common in the SLC26 family, notably also in pendrin. Based on the simulations, the extracellular site in pendrin is involved in facilitating anion access to the canonical intracellular site in a conformation-dependent manner while in prestin, the intracellular site is not accessible from the extracellular side. Furthermore, like prestin, pendrin exhibits a non-linear capacitance, an indication of voltage-dependent conformational switching. Together, these findings suggest that prestin and pendrin share core structural and functional properties, notably parallels between expansion-contraction states and anion binding sites, though transition speeds and conformation-dependent ion-accessibility may differ.

biophysics↗

A horizontally transferred fungal deubiquitinase facilitates insecticides resistance in whitefly

Horizontal gene transfer (HGT) has enabled insects to acquire novel genetic material that can fuel adaptation to environmental change. However, the role of HGT in the evolution of insecticide resistance remains poorly characterised. Here, we identify BtUCH19, a fungal gene that has integrated into the genome of the global pest Bemisia tabaci and functions as a deubiquitinating enzyme (DUB). We show that compared to endogenous DUB, BtUCH19 specifically removes K63-linked ubiquitin chains from a cytochrome P450, CYP4C64, thereby stabilizing this key detoxification enzyme in vivo. Sustained CYP4C64 abundance enhances metabolic detoxification of two commonly used insecticides thiamethoxam (TMX) and clothianidin (CLO) to their low-toxicity products TMX-Urea and CLO-Urea. Consequently, BtUCH19 drives insecticide resistance through a novel "HGT-PTM-Metab" axis. Our work reveals the instrumental role of a HGT in orchestrating ubiquitin-proteasome system (UPS)-mediated protein level regulation of a key detoxification pathway. These findings offer new insights into the intricate mechanisms underlying co-evolutionary biology, and provide a new molecular target for Integrated Pest Management (IPM).

zoology↗

Whole-genome phylogenomics and synteny resolve a single origin of body-plan asymmetry in flatfishes

Flatfishes display the most dramatic asymmetric body plan in vertebrates, yet whether this rare innovation evolved once (flatfish monophyly, FM) or multiple times (flatfish polyphyly, FP) has remained contentious. A recent genome-wide study supported FP by placing Psettodes, the earliest-diverging flatfish lineage, among symmetric relatives within Carangaria, the clade that also includes billfishes, jacks, mahi-mahi, and barracudas. Subsequent work traced this to base-composition artifacts and inadequate substitution modeling. Here we revisit the question using whole-genome phylogenomic and synteny data from 17 carangarian species spanning flatfishes and carangarian relatives. We contribute three new chromosome-level assemblies, including the first for Psettodes. Nucleotide-based coalescent analyses (e.g., ROADIES, CASTER) yield strong support for FM, with Psettodes sister to all other flatfishes. Microsynteny analyses built from conserved gene-order blocks corroborate this result: topology tests, cluster-profile counts, and rearrangement-based trees favor FM over two competing FP topologies. Macrosynteny, based on chromosome-scale rearrangements, yields a more mixed signal, with support for FM depending on the metric and taxon-sampling scheme. We interpret this scale-dependent pattern in the context of the explosive post-Cretaceous radiation of Carangaria. The short intervals between speciation events that characterize rapid radiations appear to have left sufficient signal in fine-grained microsyntenic rearrangements, while chromosome-scale rearrangements were too rare to consistently resolve these closely spaced splits. When integrated with evidence from conserved developmental mechanisms active during metamorphosis, the stage at which flatfish asymmetry first emerges, and from the exceptionally complete fossil record, our multi-scale genomic evidence supports a single evolutionary origin of flatfish asymmetry.

evolutionary biology↗