Biology subjects

Lu, T.

Publications and source records attributed to Lu, T..

At least 37 records · Page 2Linked to original sources

bioRxiv2026

Dopamine Accumulation Dynamics Control Time Perception

Accurate timing is fundamental to perception and behavior, and the dopaminergic system plays a key role. According to the dopamine clock hypothesis, elevated dopamine accelerates the interval clock, while reduced levels slow it. However, optogenetic activation of substantia nigra pars compacta (SNc) dopaminergic neurons paradoxically disrupts this model, suggesting greater complexity. To resolve this paradox, we monitored ventral tegmental area (VTA) dopamine activity in mice performing a time perception task. We observed a ramping-to-threshold pattern, where slower ramping corresponded to longer durations. Optogenetic activation accelerated time estimation, whereas inhibition prolonged it. Systemic dopamine elevation had no effect, but reuptake inhibition accelerated timing. Strikingly, prolonged high dopamine levels slowed time estimation, correlating with slower accumulation due to increased reuptake. Our findings challenge the dopamine clock hypothesis, demonstrating that time perception depends not on absolute dopamine levels but on their temporal accumulation dynamics. This revised framework reconciles previous contradictions and highlights the role of dopamine accumulation rates in temporal cognition.

neuroscience↗

bioRxiv2026

Lysosomal Aspartylglucosaminidase Couples Glycoprotein Catabolism to Cell-Surface GlycoRNA Production

GlycoRNAs, small non-coding RNAs covalently linked to N-glycans, reveal an unexpected intersection between RNA biology and glycosylation, with potential roles in immunity and cell-cell communication. The origins and biogenesis of their glycans remain unclear. Using CRISPR-Cas9 screening, metabolic glycan labeling and lysosome-targeted proteomics, we reconfirm canonical N-glycosylation enzymes (STT3A/B) and identify components of the mannose-6-phosphate (M6P) lysosomal sorting pathway (GNPTAB, M6PR) as essential contributors. Strikingly, lysosomal aspartylglucosaminidase (AGA) acts as a rate-limiting regulator, linking glycoprotein catabolism to glycoRNA formation. Loss of AGA collapses both abundance and diversity of RNA-linked N-glycans, while pulse-chase tracing shows glycoprotein-derived glycans are repurposed for RNA glycosylation. These findings position lysosomes as active participants in RNA modification and redefine glycoRNA biogenesis as a metabolically integrated process.

cell biology↗

bioRxiv2026

Functional Evaluation of TRPC6 Missense Variants in Cancer Patients via Molecular Docking Analysis Compared with Patch Clamp Electrophysiology

Gain-of-function mutations in the transient receptor potential 6 (TRPC6) channel have recently been recognized as risk factors for both doxorubicin (DOX)-induced cardiomyopathy. Functional evaluation of TRPC6 missense variants is therefore important for cancer patients undergoing anthracycline treatment. However, traditional electrophysiological methods are labor-intensive and time-consuming. In this study, we compared the functional responses of TRPC6 missense variants to 1-oleoyl-2-acetyl-sn-glycerol (OAG), a TRPC6 agonist, using molecular docking and patch clamp recording techniques. For the wild-type (WT) TRPC6 structure (PDB ID: 6UZ8), OAG exhibited a binding energy of -4.49 kcal/mol and a dissociation constant (Kd) of 0.511 mM. Twenty TRPC6 missense variants were identified from cancer patients in the Mayo Clinic database. Of these, fifteen variants had resolvable structures, nine of which displayed increased Kd values and six decreased Kd values compared to WT in molecular docking analysis. Patch clamp recordings revealed that TRPC6 WT and mutant channels were inactive at baseline but were activated upon 50 M OAG stimulation, except two loss-of-function variants. Moreover, a 24-h treatment with 0.5 M DOX significantly enhanced OAG-induced channel activation. All three variants identified in patients with heart failure demonstrated gain-of-function properties in both electrophysiological measurements and in-silico predictions. Importantly, the results obtained from molecular docking and patch clamp recordings were strongly correlated, showing an 82% concordance, higher than the predictions from AlphaMissense. These findings indicate that our computational analysis provides a rapid and reliable method for predicting the functional impact of TRPC6 missense variants, which may aid clinical decision-making in cancer patients receiving chemotherapy.

physiology↗

bioRxiv2025

Protective and pathogenic antibody responses from a primate Shigella outbreak inform vaccine design

There is currently no approved vaccine for Shigella spp., a leading cause of diarrhea that are increasingly resistant to antimicrobials. Shigella vaccine development is complicated in part by an incomplete understanding of the structural and molecular determinants of immunity. To address this, we isolated monoclonal antibodies (mAbs) against candidate Shigella vaccine antigens using samples from a Shigella flexneri outbreak in a non-human primate (NHP) research facility. We found that antibodies targeting the Shigella O-antigen (O-Ag) can undergo significant affinity maturation (>10%) to acquire broad cross-reactivity across S. flexneri serotypes. We also found that the virulence-associated type III secretion system (T3SS) proteins IpaD and IpaB elicit moderate T cell and robust antibody responses. T3SS antibodies either inhibit, or - surprisingly - enhance bacterial virulence in vitro and in vivo depending on their epitope specificity. These findings provide key insights into protective and deleterious immune responses against Shigella that directly inform vaccine immunogen design.

immunology↗

bioRxiv2025

Multimodal analysis defines GNG4 as a distinguishing feature of germinal center-positioned CD4 T follicular helper cells in humans

CD4 T follicular helper (Tfh) cells coordinate humoral immune responses within germinal centers (GC) of lymphoid tissue. Despite their critical roles in vaccination and autoimmunity, the gene expression programs that define functionally distinct human Tfh states-- and the molecular pathways engaged by Tfh positioned within the GC niche--remain incompletely understood. This gap has limited translational efforts to monitor or therapeutically target specific Tfh states for clinical benefit. Here, we delineate human CD4 T cell heterogeneity in tonsils and peripheral blood using trimodal single-cell sequencing and spectral flow cytometry to define epigenomic, transcriptional, and proteomic features of distinct Tfh states. Tfh with a GC-like phenotype exhibited markedly increased chromatin accessibility and both mRNA and protein expression of G protein subunit gamma 4 (GNG4). In tonsil, single-cell spatial transcriptomics defined GNG4 expression as a distinguishing feature of activated Tfh states within spatially demarcated GC compartments, with greater specificity than conventionally GC-associated features such as BCL6, TOX2, and S1PR2. In contrast, GNG4- Tfh primarily localized to nonGC regions and exhibited a resting, Th17-polarized phenotype. Together, these data highlight GNG4 as a central feature of activated, GC-positioned Tfh cell identity in humans. One Sentence SummaryGNG4 expression defines activated CD4 T follicular helper cells localized to the germinal center of human lymphoid tissue.

immunology↗

bioRxiv2025

AAV vectors with enhancer-controlled ITR promoters

Adeno-associated virus (AAV) is limited by its packaging capacity and the unwanted promoter activity of inverted terminal repeats (ITRs). Here we utilized mini-enhancers to regulate ITR promoters and drive AAV cargo expression in the absence of the canonical promoters, which not only solved the ITR issue but also released more payload for the cargo. As an example, this new design successfully enabled robust, tissue-specific SpCas9 gene editing via a single AAV, which otherwise requires a dual-AAV system due to the large size of SpCas9.

bioengineering↗

bioRxiv2025

Dynamic optimization of chemo-immunotherapy sequencing reveals phenotype-dependent regimens across tumor immune microenvironments

Cytotoxic chemotherapy and immune checkpoint inhibitors (ICIs) have transformed the management of advanced cancers, yet durable responses remain restricted to subsets of patients and strongly depend on the tumor immune microenvironment (TIME). Distinct "hot" and "cold" TIMEs differ in pre-existing effector T-cell activity and treatment-induced immunogenicity, suggesting that combination regimens should be tailored to microenvironmental context under realistic clinical constraints. Here we develop a deterministic dynamic optimization framework that jointly designs chemotherapy and ICI dosing schedules on a mechanistic tumor-immune model. The model tracks sensitive and resistant tumor cells, effector CD8+ T cells and circulating drug concentrations with pharmacodynamic couplings encoding immunogenic cell death and checkpoint inhibition. We formulate a continuous-time optimal control problem that balances tumor burden against drug exposure while enforcing cumulative dose limits, end-of-interval concentration bounds and bounds on stepwise changes in infusion rates. Using gradient-based optimization with embedded forward sensitivities, we solve the resulting nonlinear programs for four representative TIME phenotypes (extremely cold, hot, cold and cold with high antigenic resistance). The optimizer recovers qualitatively distinct and biologically interpretable regimens, including chemotherapy-dominated schedules in extremely cold TIMEs, aggressive early ICI administration in hot TIMEs and minimal ICI pulses in cold TIMEs. Alternative weightings of treatment objectives reveal trade-offs between tumor eradication and effector preservation. These results show that constrained dynamic optimization can systematically derive phenotype-specific, mechanistically consistent combination strategies and provide a reusable computational module for integrating TIME-resolved models into in silico trial and quantitative systems pharmacology workflows. Author summaryImmune checkpoint inhibitors (ICI) have transformed cancer therapy, yet their benefit varies dramatically across tumor immune microenvironments (TIMEs). In the clinic, ICI is often combined with chemotherapy, and clinicians must decide not only whether to use ICI, but also how to schedule both agents over months of treatment. We develop a reusable dynamic optimization framework that takes any ordinary differential equation model of tumor-immune-therapy interactions as input, enforces clinically motivated dosing and toxicity constraints, and outputs optimal chemo-ICI regimens. Using a mechanistic model and four virtual patients representing hot, cold, and extremely cold TIMEs, we show that the framework automatically suppresses futile ICI dosing in immune deserts, while allocating aggressive combination therapy to highly ICI-responsive tumors.

bioinformatics↗

bioRxiv2025

PIWIL3-piRNA Pathway Is Essential for Rabbit Oogenesis and Embryogenesis via Broad Regulation of the Transcriptome and Proteome

Female infertility represents a significant challenge in reproductive medicine. Although it is known to be primarily due to oogenic and early embryonic failures, the molecular mechanisms underlying these failures remain elusive. The Piwi-piRNA pathway is crucial for gametogenesis in diverse organisms. Yet, its role in mammalian female fertility is unclear. This is partly because most studies are done in mice, which contain only PIWIL1, PIWIL2, and PIWIL4 that are essential for spermatogenesis but not for oogenesis. PIWIL3 emerges in higher mammals and is highly expressed in human oocytes. Interestingly, female PIWIL3-knockout golden hamsters exhibit only reduced fertility without detectable defects in oogenesis. This has left the function of PIWIL3 in higher mammals, including humans, unexplored. Here, we discovered that PIWIL3 in the rabbit (Oryctolagus cuniculus) shares high homology with human PIWIL3. It is the predominant PIWI protein in oocytes in both species. Using CRISPR-cas9-mediated knockout, we demonstrated that rabbit PIWIL3 is essential for female fertility. Its loss leads to severe defects in oogenesis. Moreover, embryos lacking maternal PIWIL3 arrest developmentally at the 8-cell stage. Mechanistically, rabbit PIWIL3 binds [~]18-nucleotide piRNAs, mirroring the behavior of human PIWIL3, and is critical for piRNA biogenesis. Moreover, it regulates transcriptomic and proteomic landscapes and silences a broad array of transposons during late oogenesis yet activates another set of transposons during early embryogenesis. These findings establish PIWIL3 as a pivotal dual regulator of gene expression and transposon activity, which is essential for oogenesis and early embryogenesis in non-rodent mammals, potentially including humans.

developmental biology↗

bioRxiv2025

Leveraging protein representations to explore uncharted fold spaces with generative models

A major challenge in computational de novo protein design is the exploration of uncharted areas within the protein structural space. However, the large degrees of freedom of protein backbones complicate the sampling process during protein design. Machine learning-based models have made great strides in this problem, however due to their nature they tend to exploit rather than explore the data distribution used for training the neural networks. To address some of these challenges, we propose a new coarse grained protein structure representation generative method, DiffTopo, a diffusion model which increases the sampling efficiency and diversity. Combined with a backbone level protein generative model like RFdiffusion, novel protein folds can be generated rapidly, allowing for efficient exploration of the designable topology space. Interestingly, we have discovered that by mirroring the topological organization of native proteins using a pipeline named MirrorTopo, we can readily expand the known fold space. We generated and experimentally characterized 30 different novel topologies from DiffTopo and 6 different novel mirror topologies from MirrorTopo. The developed framework relying on low resolution sampling provides new means for fold exploration challenges, which could in principle enhance our knowledge of the first principles of protein structure and folding, as well as create new opportunities for functional design.

bioinformatics↗

bioRxiv2025

SLAE: Strictly Local All-atom Environment for Protein Representation

AO_SCPLOWBSTRACTC_SCPLOWBuilding physically grounded protein representations is central to computational biology, yet most existing approaches rely on sequence-pretrained language models or backbone-only graphs that overlook side-chain geometry and chemical detail. We present SLAE, a unified all-atom framework for learning protein representations from each residues local atomic neighborhood using only atom types and interatomic geometries. To encourage expressive feature extraction, we introduce a novel multi-task autoencoder objective that combines coordinate reconstruction, sequence recovery, and energy regression. SLAE reconstructs allatom structures with high fidelity from latent residue environments and achieves state-of-the-art performance across diverse downstream tasks via transfer learning. SLAEs latent space is chemically informative and environmentally sensitive, enabling quantitative assessment of structural qualities and smooth interpolation between conformations at all-atom resolution.

bioinformatics↗

bioRxiv2025

Ensemble-conditioned protein sequence design with Caliby

Structure-conditioned sequence design models aim to design a protein sequence that will fold into a given target structure. Deep-learning-based approaches for sequence design have proven highly successful for various protein design applications, but many non-idealized backbones still remain out of reach for current models under typical in silico success criteria. We hypothesize that training objectives prioritizing native sequence recovery unintentionally push models to reproduce non-structural signals (e.g. phylogenetic relatedness, neutral drift, or dataset sampling biases), rather than a broadly generalizable structure-sequence mapping. Inspired by recent work bridging sequence likelihood and fitness prediction in protein language models, we introduce Caliby, a Potts model-based sequence design method capable of conditioning on an ensemble of structures. Conditioning on a synthetic ensemble generated from an input backbone allows sampling of sequences consistent with the structural constraints of the ensemble while averaging out undesired biases towards the native sequence. Ensemble-conditioned sequence design with Caliby reduces native sequence recovery while substantially improving AlphaFold2 self-consistency, outperforming state-of-the-art models ProteinMPNN and ChromaDesign on both native and de novo backbones. Finally, we train a variant of Caliby on only soluble proteins and demonstrate in silico that Protpardelle-1c binder designs that were previously deemed undesignable by SolubleMPNN are actually designable under SolubleCaliby, highlighting limitations of existing filtering pipelines. These results suggest that Caliby can expand the de novo design space beyond highly idealized backbones.

bioengineering↗

bioRxiv2025

Challenges to case-only analysis for gene-environment interaction detection using polygenic risk scores: model assumptions and biases in large biobanks

Gene-environment interaction is important for studying complex diseases. Case-only analysis has been proposed to improve power for GxE detection. However, case-only analysis relies on key assumptions, including correct specification of the disease risk model and marginal independence between genetic and environmental variables. In this study, we systematically investigate the challenges of case-only analysis using polygenic risk scores (PRS) as genetic variables in large biobanks. Through simulations, we demonstrate that the false positive control of PRS-based case-only analysis depends on the log-linear disease risk model and weak main effects, and that it is prone to false positives under other commonly used disease risk models. We then conduct case-only analyses for breast cancer, prostate cancer, class 3 obesity, and short stature in the UK Biobank, using PRS derived from non-overlapping chromosome sets (e.g., even-numbered and odd-numbered chromosomes) that are unlikely to interact with each other. The resulting case-only regression estimates consistently show negative shifts compared to population-based estimates, suggesting false positives driven by collider bias due to model misspecification. Furthermore, correlations between chromosome set-specific PRS, likely driven by assortative mating or population stratification, suggest additional sources of confounding. Our results underscore the challenges of applying PRS-based case-only analysis in large biobank settings and highlight the need for caution when interpreting case-only results.

genetics↗

bioRxiv2025

Conditional Protein Structure Generation with Protpardelle-1c

We present Protpardelle-1c, a collection of protein structure generative models with robust motif scaffolding and support for multi-chain complex generation under hotspot-conditioning. Enabling sidechain-conditioning to a backbone-only model increased Protpardelle-1cs MotifBench score from 4.97 to 28.16, outperforming RFdiffusions 21.27. The crop-conditional all-atom model achieved 208 unique solutions on the La-Proteina all-atom motif scaffolding benchmark, on par with La-Proteina while having ~10 times fewer parameters. At 22M parameters, Protpardelle-1c enables rapid sampling, taking 40 minutes to sample all 3000 MotifBench backbones on an NVIDIA A100-80GB, compared to 31 hours for RFdiffusion.

bioengineering↗

bioRxiv2025

A High-throughput Multi-Species Platform Using Biolayer Interferometry Immunosorbent Assay (BLI-ISA) as an Alternative to Indirect ELISA for Vaccine Development

In vaccine development, the ELISA (Enzyme-Linked Immunosorbent Assay) is commonly used to compare the antibody titers of samples from several treatment groups. This often requires extensive sample preparation, manual labor, and long incubation and processing times. Biolayer Interferometry (BLI) has emerged as an alternative to the ELISA for the detection and quantification of antigen-specific antibodies in biological samples. However, the implementation of BLI as a replacement for the ELISA in vaccine development requires that experimental parameters are established for accurate and reproducible results. Here we give a general protocol for a biolayer interferometry immunosorbent assay (BLI-ISA) for the comparison of antigen-specific antibody levels in treatment group sera that uses secondary antibody binding responses as replacement for ELISA endpoint titers. We also validate that this BLI-ISA yields the same results as the ELISA endpoint titer while requiring far less time and effort.

immunology↗

bioRxiv2025

NTM-DB: A Comprehensive Non-Tuberculosis Mycobacteria Genomic Database

Non-tuberculous mycobacteria (NTM) are a major group of environmental bacteria, with approximately one-third of them causing serious human infections, particularly respiratory diseases. The global rise in the prevalence and severity of NTM infections has posed a major public health challenge. While high-throughput sequencing has generated vast genomic data on NTM, there remains a lack of comprehensive resources for cross-species genomic analysis. To address these limitations, we have developed a specialized database called NTM-DB (https://ngdc.cncb.ac.cn/ntmdb) tailored for NTM researchers and clinicians. NTM-DB offers the most comprehensive collection of NTM genomic and bioinformatic resources, including 16,469 genome assemblies (13,134 newly assembled genomes), 189 type/standard strain genomes representing 177 species and 12 subspecies, 705 MLST types, 33,240 resistance genes, and 74,315 virulence genes. A user-friendly interactive website has been constructed to enable efficient browsing, MLST profiling, searching, online analysis, and downloading of the aforementioned data. Notably, with online analysis tools, users can perform customized genotyping, cross-species phylogeny, pan-genome, and virulence and drug resistance gene annotation analyses using our data and/or their uploaded data. Overall, with its comprehensive data, intuitive interface, and powerful analysis tools, NTM-DB serves as an important resource and reference for NTM researchers and clinicians, improving diagnosis and treatment for various NTM-related diseases, and supporting both scientific discovery and clinical practice.

microbiology↗

bioRxiv2025

TESS: A Forward Simulation Framework for Studying the Role of Transposable Elements in Genome Expansion and Contraction

Genome expansion and contraction are reportedly driven by transposable element (TE) activity, but the underlying dynamics remain enigmatic due to a lack of historical records tracing these changes. Here, we present PrinTE for versatile, forward-time simulation of whole-genome sequences with highly customizable transposon dynamics. Through simulations, we confirm that the distribution of TE sequence divergence reflects their historical insertion and deletion dynamics, which can be used to infer TE dynamic parameters through PrinTE simulations. We analyzed the pangenome of Pucciniomycotina, a subdivision of fungi containing myrtle rust (Austropuccinia psidii), which drastically expanded its genome size to 1018 Mb. Our analyses reveal that the best strategy for controlling genome size is to avoid the invasion of LTR retrotransposons (LTR-RTs). While illegitimate recombination (IR) is considered the most effective counteraction of LTR-RT invasions leaving only solo LTR remnants, we observed a strong positive correlation between solo:intact LTR ratio (strength of LTR-RT removal) and genome size (r = 0.65), and a near-linear correlation between solo LTR count and genome size (r = 0.98). This result suggests that IR alone may not effectively prevent genome obesity. Through simulation of Pucciniomycotina genomes, we proposed that A. psidii might experience a prolonged period of genome expansion followed by a short, potent, and likely ongoing period of contraction. PrinTE is freely available at https://github.com/cwb14/PrinTE.git.

bioinformatics↗

bioRxiv2025

MedSAGE: Bridging Generative AI and Medicinal Chemistry for Structure-Based Design of Small Molecule Drugs

While generative AI is transforming the de novo design of proteins, its effectiveness for structure-based design of small molecules remains limited. Current methods, including diffusion models, often produce small molecules with difficult-to-synthesize structures, poor medicinal chemistry properties, and limited target selectivity. To address these limitations, we introduce MedSAGE, a novel generative AI framework that adapts diffusion models specifically for de novo small-molecule design. Rather than using atoms or strings, we develop a novel representation for generating molecules using fragments relevant for medicinal chemistry. Chemical and geometric information characterizing these fragments is embedded in a smooth and interpretable latent space. We also develop an algorithm to optimize the connectivity between generated fragments while preserving chemical validity and synthesizability. In a benchmark of multiple methods across 25 therapeutically relevant protein targets, MedSAGE achieved state-of-the-art performance, producing synthesizable, drug-like molecules with predicted affinity and selectivity closely matching known drugs and drug candidates. Compared to large-scale virtual screening, MedSAGE produced molecules with high predicted affinity over 100 times more efficiently. Our results demonstrate that MedSAGE is already practically useful and paves the way for next-generation tools in structure-guided drug design.

biophysics↗

bioRxiv2025

Molecular insights into early malignant transition of hepatocellular carcinoma

The molecular continuum of premalignant-to-malignant transition remains elusive in carcinogenesis, primarily due to the difficulty in sampling transitional lesions. Here, we present comprehensive genomic and immunological profiling of 21 very early hepatocellular carcinomas (veHCCs) arising within 17 cancer-prone DNs. Surprisingly, 82% of cancer-prone DNs harbored TERT alterations, suggesting a predisposing rather than causative role in malignancy transition. A substantial increase in CNA burden, rather than SNV, was noted, indicating a role of chromosome instability in malignancy transition. Additionally, veHCC-originating DNs showed immune inactivity, not falling into the prevailing paradigm that HCCs develop in a context of chronic inflammation. 43% of veHCCs showed an inflamed phenotype with relatively mild CNA burden but already exhibited immune evasion features. Two major evolutionary scenarios were thus proposed: 1) CNA-dominant progression and 2) early immune evasion of those with mild CNA burden. Collectively, our findings illustrate previously unexplored molecular paradigms in HCC initiation, highlighting the therapeutic potential of immunotherapy for early intervention.

cancer biology↗