Biology subjects

Chen, T.

Publications and source records attributed to Chen, T..

At least 181 records · Page 10Linked to original sources

bioRxiv2023

The ICF syndrome protein CDCA7 harbors a unique DNA-binding domain that recognizes a CpG dyad in the context of a non-B DNA

CDCA7, encoding a protein with a C-terminal cysteine-rich domain (CRD), is mutated in immunodeficiency, centromeric instability and facial anomalies (ICF) syndrome, a disease related to hypomethylation of juxtacentromeric satellite DNA. How CDCA7 directs DNA methylation to juxtacentromeric regions is unknown. Here, we show that the CDCA7 CRD adopts a unique zinc-binding structure that recognizes a CpG dyad in a non-B DNA formed by two sequence motifs. CDCA7, but not ICF mutants, preferentially binds the non-B DNA with strand-specific CpG hemi-methylation. The unmethylated sequence motif is highly enriched at centromeres of human chromosomes, whereas the methylated motif is distributed throughout the genome. At S phase, CDCA7, but not ICF mutants, is concentrated in constitutive heterochromatin foci, and the formation of such foci can be inhibited by exogenous hemi-methylated non-B DNA bound by the CRD. Binding of the non-B DNA formed in juxtacentromeric regions during DNA replication provides a mechanism by which CDCA7 controls the specificity of DNA methylation.

molecular biology↗

bioRxiv2023

Engineering self-propelled tumor-infiltrating CAR T cells using synthetic velocity receptors

Chimeric antigen receptor (CAR) T cells express antigen-specific synthetic receptors, which upon binding to cancer cells, elicit T cell anti-tumor responses. CAR T cell therapy has enjoyed success in the clinic for hematological cancer indications, giving rise to decade-long remissions in some cases. However, CAR T therapy for patients with solid tumors has not seen similar success. Solid tumors constitute 90% of adult human cancers, representing an enormous unmet clinical need. Current approaches do not solve the central problem of limited ability of therapeutic cells to migrate through the stromal matrix. We discover that T cells at low and high density display low- and high-migration phenotypes, respectively. The highly migratory phenotype is mediated by a paracrine pathway from a group of self-produced cytokines that include IL5, TNF, IFN{gamma}, and IL8. We exploit this finding to "lock-in" a highly migratory phenotype by developing and expressing receptors, which we call velocity receptors (VRs). VRs target these cytokines and signal through these cytokines cognate receptors to increase T cell motility and infiltrate lung, ovarian, and pancreatic tumors in large numbers and at doses for which control CAR T cells remain confined to the tumor periphery. In contrast to CAR therapy alone, VR-CAR T cells significantly attenuate tumor growth and extend overall survival. This work suggests that approaches to the design of immune cell receptors that focus on migration signaling will help current and future CAR cellular therapies to infiltrate deep into solid tumors.

immunology↗

bioRxiv2023

scELMo: Embeddings from Language Models are Good Learners for Single-cell Data Analysis

Various Foundation Models (FMs) have been built based on the pre-training and fine-tuning framework to analyze single-cell data with different degrees of success. In this manuscript, we propose a method named scELMo (Single-cell Embedding from Language Models), to analyze single-cell data that utilizes Large Language Models (LLMs) as a generator for both the description of metadata information and the embeddings for such descriptions. We combine the embeddings from LLMs with the raw data under the zero-shot learning framework to further extend its function by using the fine-tuning framework to handle different tasks. We demonstrate that scELMo is capable of cell clustering, batch effect correction, and cell-type annotation without training a new model. Moreover, the fine-tuning framework of scELMo can help with more challenging tasks including in-silico treatment analysis or modeling perturbation. scELMo has a lighter structure and lower requirements for resources. Our method also outperforms recent large-scale FMs (such as scGPT [1], Geneformer [2]) and other LLM-based single-cell data analysis pipelines (such as GenePT [3] and GPTCelltype [4]) based on our evaluations, suggesting a promising path for developing domain-specific FMs.

bioinformatics↗

bioRxiv2023

PROTEOME-SCALE RECOMBINANT STANDARDS AND A ROBUST HIGH-SPEED SEARCH ENGINE TO ADVANCE CROSS-LINKING MS-BASED INTERACTOMICS

AO_SCPLOWBSTRACTC_SCPLOWAdvancing data analysis tools for proteome-wide cross-linking mass spectrometry (XL-MS) requires ground-truth standards that mimic biological complexity. Here, we develop wellcontrolled XL-MS standards comprising hundreds of recombinant proteins that are systematically mixed for cross-linking. We use one standard dataset to guide the development of Scout, a search engine for XL-MS with MS-cleavable cross-linkers. Using other, independent datasets from our standards as well as published datasets, we benchmark the performance of Scout and existing XL-MS software. This demonstrates that Scout offers the best combination of speed, sensitivity, and false-discovery rate control. These results illustrate how our large recombinant standards can support the development of XL-MS analysis tools and evaluation of XL-MS results.

bioinformatics↗

bioRxiv2023

Multifrequency control of Faraday wave bioassembly for constructing multiscale hPSC-derived neuronal networks

Bioassembly is recently regarded as a critical alternative biofabrication technical route to bioprinting since it can directly manipulate millions of live cells to form multicellular structures with close intercellular proximity, improving contact-dependent cell communication and promoting the emergence of tissue-specific functions. However, acoustic bioassembly techniques are currently limited to generating cytoarchitecture with a single characteristic length which cannot faithfully mimic the multiscale cellular structures in native tissues. To overcome this challenge, herein we report a novel acoustic bioassembly technique that employs multifrequency control of Faraday waves to form multiscale cellular structures. By superimposing multiple sine wave signals with proper amplitude ratios, Faraday waves containing multiple wavelengths can be induced and enabled to generate multiscale structures in few seconds. Using this technique, we construct functional neuronal networks with multiscale connectivity that display spontaneous neuroelectrical activities. We anticipate this technique will find wide applications in tissue engineering and regenerative medicine.

bioengineering↗

bioRxiv2023

Filter-aided expansion proteomics

Integration of hydrogel-based tissue expansion and mass spectrometry-based proteomics enables high spatial resolution analysis of global protein expression in tissues. Here, we introduce a filter-aided tissue expansion proteomics (FAXP) method with optimized hydrogel preparation and treatment steps for spatial proteomics analysis of formalin-fixed paraffin-embedded (FFPE) specimens. Compared with our original ProteomEx method, FAXP, partially automated with robotics, exhibited 14.5-fold higher volumetric resolution, increased peptide yield leading to 250% more protein identifications, and 50% time consumption for sample preparation. We demonstrated its application in clinical colorectal tissue samples. We further integrated it with laser capture microdissection for proteomic analysis of subcellular organelles.

biochemistry↗

bioRxiv2023

Proteomic Features of Adolescents and Young Adults with Soft Tissue Tumours

Adolescents and young adult (AYA) patients with soft tissue tumours (STT) including sarcomas are an underserved group with disparities in treatment outcomes. To define the molecular features between AYA and older adult (OA) patients, we analysed the proteomic profiles of a large cohort of STT across 10 histological subtypes (AYA n=66, OA n=243). AYA tumours are enriched in proteins involved in mitochondrial metabolism while OA patients have elevated inflammatory and cell cycle signalling. By integrating the patient-level proteomic data with functional genomic profiles from sarcoma cell lines, we show that the mRNA splicing pathway is an intrinsic vulnerability in cell lines from OA patients and that components of the spliceosome complex are independent prognostic factors for metastasis free survival in AYA patients. Our study highlights the importance of performing age-specific molecular profiling studies to identify risk stratification tools and targeted agents tailored for the clinical management of AYA patients.

cancer biology↗

bioRxiv2023

Enhancing CAR-T Cell Metabolism to Overcome Hypoxic Conditions in the Brain Tumor Microenvironment

The efficacy of chimeric antigen receptor (CAR)-T therapy has been limited against brain tumors to date. CAR-T cells infiltrating syngeneic intracerebral SB28-EGFRvIII glioma revealed impaired mitochondrial ATP production and a markedly hypoxic status compared to ones migrating to subcutaneous tumors. Drug screenings to improve metabolic states of T cells under hypoxic conditions led us to evaluate the combination of AMPK activator Metformin and the mTOR inhibitor Rapamycin (Met+Rap). Met+Rap-pretreated mouse CAR-T cells showed activated PPAR-gamma coactivator 1 (PGC-1) through mTOR inhibition and AMPK activation, and a higher level of mitochondrial spare respiratory capacity than those pretreated with individual drugs or without pretreatment. Moreover, Met+Rap-pretreated CAR-T cells demonstrated persistent and effective anti-glioma cytotoxic activities in the hypoxic condition. Furthermore, a single intravenous infusion of Met+Rap-pretreated CAR-T cells significantly extended the survival of mice bearing intracerebral SB28-EGFRvIII gliomas. Mass cytometric analyses highlighted increased glioma-infiltrating CAR-T cells in the Met+Rap group with fewer Ly6c+ CD11b+ monocytic myeloid-derived suppressor cells in the tumors. Finally, human CAR-T cells pretreated with Met+Rap recapitulated the observations with murine CAR-T cells, demonstrating improved functions in vitro hypoxic conditions. These findings advocate for translational and clinical exploration of Met+Rap-pretreated CAR-T cells in human trials.

immunology↗

bioRxiv2023

Poisoning medical knowledge using large language models

Biomedical knowledge graphs constructed from scientific literature have been widely used to validate biological discoveries and generate new hypotheses. Recently, large language models (LLMs) have demonstrated a strong ability to generate human-like text data. While most of these text data have been useful, LLM might also be used to generate malicious content. Here, we investigate whether it is possible that a malicious actor can use LLM to generate a malicious paper that poisons scientific knowledge graphs and further affects downstream biological applications. As a proof-of-concept, we develop Scorpius, a conditional text generation model that generates a malicious paper abstract conditioned on a promoting drug and a target disease. The goal is to fool the knowledge graph constructed from a mixture of this malicious abstract and millions of real papers so that knowledge graph consumers will misidentify this promoting drug as relevant to the target disease. We evaluated Scorpius on a knowledge graph constructed from 3,818,528 papers and found that Scorpius can increase the relevance of 71.3% drug disease pairs from the top 1000 to the top 10 by only adding one malicious abstract. Moreover, the generation of Scorpius achieves better perplexity than ChatGPT, suggesting that such malicious abstracts cannot be efficiently detected by humans. Collectively, Scorpius demonstrates the possibility of poisoning scientific knowledge graphs and manipulating downstream applications using LLMs, indicating the importance of accountable and trustworthy scientific knowledge discovery in the era of LLM.

bioinformatics↗

bioRxiv2023

Targeting phosphoRab-RILPL Interactions as a Strategy to Downregulate Pathogenic LRRK2 in Parkinson's Disease

Familial Parkinsons disease (PD) is frequently linked to multiple disease-causing mutations within Leucine-Rich Repeat Protein Kinase 2 (LRRK2), leading to aberrant kinase activity. Multiple pathogenic effects of enhanced LRRK2 activity have been identified including loss of cilia and centrosomal cohesion defects. When phosphorylated by LRRK2, Rab8a and Rab10 bind to phospho-specific RILPL effector proteins. RILPL-mediated accumulation of pRabs proximal to the mother centriole is critical for initiating deficits in ciliogenesis and centrosome cohesion mediated by LRRK2. We hypothesized that Rab-derived phospho-mimics may serve to block phosphorylated Rab proteins from docking with RILPL in the context of hyperactive LRRK2 mutants. This would serve as an alternative strategy to downregulate pathogenic signaling mediated by LRRK2, rather than targeting LRRK2 kinase activity itself. To test this theory, we designed a series of constrained peptides mimicking phosphorylated Switch II derived from Rab8. These RILPL interacting peptides, termed RIP, were further shown to permeate cells. Further, several peptides were found to bind RILPL2 and restore ciliogenesis and centrosomal cohesion defects in cells expressing PD-associated mutant LRRK2. This research demonstrates the utility of constrained peptides as downstream inhibitors to target pathogenic LRRK2 activity and may provide an alternative approach to target specific pathways activated by LRRK2.

biochemistry↗

bioRxiv2023

Vegetation of Chamaecyparis montane cloud forest in Lalashan Forest Dynamics Plot

To understand the vegetation-environment relationships within the Chamaecyparis montane mixed cloud forest in Taiwan, we established a 1-ha Lalashan Forest Dynamics Plot (LFDP) in northern Taiwan (24{degrees}42D N, 121{degrees}26D E). We established the plot in July 2019 and finished the first census of all woody species in August 2020. We collected environmental factors related to the topography and soil properties, measured microclimate and soil moisture within the plot, and collected further microclimatic data with a nearby weather station. In total, we recorded 5220 individuals belonging to 65 species, 42 genera and 29 families, with a basal area of 69.1 m2 ha-1, dominated by Chamaecyparis obtusa var. formosana, Rhododendron formosanum and Quercus sessilifolia. Modified TWINSPAN classified vegetation into three types (ridge, east-facing slope and valley). Unconstrained ordination showed that the main gradients behind compositional changes are related to windwardness and convexity. The prevailing wind direction in the area is from the northeast, linked to the winter monsoon. Both east-facing slope type and valley type have relatively lower temperatures than ridge type, especially during summer. Convexity is related to soil moisture gradient (from dryer convex to wet concave sites). Fog frequency is seasonal, with the highest values during autumn and winter months. From soil properties, pH is negatively and phosphorus is positively related to topographical convexity. Litter decomposition is linked to both topographical, soil and biotic variables. Collected data will serve as a baseline for future resurveys and monitoring changes within this montane cloud forest.

ecology↗

bioRxiv2023

Warm temperature suppresses plant systemic acquired resistance by intercepting the N-hydroxypipecolic acid immune pathway

Climate warming influences disease development by targeting critical components of the plant immune system, including pattern-triggered immunity (PTI), effector-triggered immunity (ETI) and production of the central defence hormone salicylic acid (SA) at the primary pathogen infection site. However, it is not clear if and/or how temperature impacts systemic immunity. Here we show that pathogen-triggered systemic acquired resistance (SAR) in Arabidopsis thaliana is suppressed at elevated temperature. This was accompanied by global downregulation of SAR-induced genes at elevated temperature. Abolished SAR under warmer conditions was associated with reduced biosynthesis of the SAR metabolite N-hydroxypipecolic acid (NHP) in Arabidopsis and other plant species (such as tomato and rapeseed), as demonstrated by downregulation of NHP biosynthetic genes (ALD1 and FMO1) and reduced NHP and pipecolic acid (Pip) levels. Although multiple SAR signals have been shown previously, exogenous NHP or Pip was sufficient to restore disease protection at elevated temperature, indicating that heat-mediated SAR suppression is due to downregulation of the NHP pathway. Along with ALD1 and FMO1, local and systemic expression of the SA biosynthetic gene ICS1 were also suppressed at warm temperature. Finally, we define a transcriptional network controlling thermosensitive NHP pathway via the master transcription factors CBP60g and SARD1. Our findings demonstrate that warm temperatures impact not only local but also systemic immunity by impinging on NHP biosynthesis, providing a roadmap towards engineering climate-resilient plant immune systems.

plant biology↗

bioRxiv2023

Structural and molecular basis of choline uptake into the brain by FLVCR2

Choline is an essential nutrient that the human body needs in vast quantities for cell membrane synthesis, epigenetic modification, and neurotransmission. The brain has a particularly high demand for choline, but how it enters the brain has eluded the field for over fifty years. The MFS transporter FLVCR1 was recently determined to be a choline transporter, and while this protein is not highly expressed at the blood-brain barrier (BBB), its relative FLVCR2 is. Previous studies have shown that mutations in human Flvcr2 cause cerebral vascular abnormalities, hydrocephalus, and embryonic lethality, but the physiological role of FLVCR2 is unknown. Here, we demonstrate both in vivo and in vitro that FLVCR2 is a BBB choline transporter and is responsible for the majority of choline uptake into the brain. We also determine the structures of choline-bound FLVCR2 in the inward- and outward-facing states using cryo-electron microscopy to 2.49 and 2.77 [A] resolution, respectively. These results reveal how the brain obtains choline and provide molecular-level insights into how FLVCR2 binds choline in an aromatic cage and mediates its uptake. Our work could provide a novel framework for the targeted delivery of neurotherapeutics into the brain.

biochemistry↗

bioRxiv2023

Ensembled best subset selection using summary statistics for polygenic risk prediction

Polygenic risk scores (PRS) enhance population risk stratification and advance personalized medicine, yet existing methods face a tradeoff between predictive power and computational efficiency. We introduce ALL-Sum, a fast and scalable PRS method that combines an efficient summary statistic-based L0L2 penalized regression algorithm with an ensembling step that aggregates estimates from different tuning parameters for improved prediction performance. In extensive large-scale simulations across a wide range of polygenicity and genome-wide association studies (GWAS) sample sizes, ALL-Sum consistently outperforms popular alternative methods in terms of prediction accuracy, runtime, and memory usage. We analyze 27 published GWAS summary statistics for 11 complex traits from 9 reputable data sources, including the Global Lipids Genetics Consortium, Breast Cancer Association Consortium, and FinnGen, evaluated using individual-level UKBB data. ALL-Sum achieves the highest accuracy for most traits, particularly for GWAS with large sample sizes. We provide ALL-Sum as a user-friendly command-line software with pre-computed reference data for streamlined user-end analysis.

genetics↗

bioRxiv2023

The Discovery and Characterization of 1,4-Dihydroxy-2-naphthoic Acid Prenyltransferase Involved in the Biosynthesis of Anthraquinones in Rubia cordifolia

Anthraquinones constitute the largest group of natural quinones, which are used as safe natural dyes and have many pharmaceutical applications. In plants, anthraquinones are biosynthesized through two main routes: the polyketide pathway and the shikimate pathway. The shikimate pathway primarily forms alizarin-type anthraquinones, and the prenylation of 1,4-dihydroxy-2-naphthoic acid is the first pathway-specific step. However, the prenyltransferase responsible for this key step remains uncharacterized. In this study, the cell suspension culture of Rubia cordifolia, a plant rich in alizarin-type anthraquinones, was used in target prenyltransferase mining. The microsomal protein prepared from the cell suspension culture prenylated 1,4-dihydroxy-2-naphthoic acid to form 2-carboxyl-3-prenyl-1,4-naphthoquinone and 3-prenyl-1,4-naphthoquinone. Then a candidate gene belonging to UbiA superfamily, RcDT1, was discovered to account for the prenylation activity. Substrate specificity studies revealed that the recombinant RcDT1 recognized naphthoic acids primarily, followed by 4-hydroxyl benzoic acids. The prenylation activities of R. cordifolia microsomes and the recombinant RcDT1 were both strongly inhibited by 1,2- and 1,4-dihydroxynaphthalene. The plastid localization and root-specific expression further confirmed the participation of RcDT1 in anthraquinone biosynthesis. The phylogenetic analyses of RcDT1 and its rubiaceous homologs indicated that DHNA-prenylation activity evolved convergently in Rubiaceae via recruitment from the ubiquinone biosynthetic pathway. The discovery and evolutionary studies of RcDT1 provide useful guidance for identifying additional and evolutionarily varied prenyltransferases which enable entry into quinones derived from shikimate pathway. Moreover, these findings will have profound implications for understanding the biosynthetic process of the anthraquinone/naphthoquinone ring derived from shikimate pathway.

plant biology↗

bioRxiv2023

Functional connectome through the human life span

The lifespan growth of the functional connectome remains unknown. Here, we assemble task-free functional and structural magnetic resonance imaging data from 33,250 individuals aged 32 postmenstrual weeks to 80 years from 132 global sites. We report critical inflection points in the nonlinear growth curves of the global mean and variance of the connectome, peaking in the late fourth and late third decades of life, respectively. After constructing a fine-grained, lifespan-wide suite of system-level brain atlases, we show distinct maturation timelines for functional segregation within different systems. Lifespan growth of regional connectivity is organized along a primary-to-association cortical axis. These connectome-based normative models reveal substantial individual heterogeneities in functional brain networks in patients with autism spectrum disorder, major depressive disorder, and Alzheimers disease. These findings elucidate the lifespan evolution of the functional connectome and can serve as a normative reference for quantifying individual variation in development, aging, and neuropsychiatric disorders.

neuroscience↗

bioRxiv2023

Glioma-neuronal circuit remodeling induces regional immunosuppression

Neuronal activity-driven mechanisms impact glioblastoma cell proliferation and invasion1-7, and glioblastoma remodels neuronal circuits8,9. Distinct intratumoral regions maintain functional connectivity via a subpopulation of malignant cells that mediate tumor-intrinsic neuronal connectivity and synaptogenesis through their transcriptional programs8. However, the effects of tumor-intrinsic neuronal activity on other cells, such as immune cells, remain unknown. Here we show that regions within glioblastomas with elevated connectivity are characterized by regional immunosuppression. This was accompanied by different cell compositions and inflammatory status of tumor-associated macrophages (TAMs) in the tumor microenvironment. In preclinical intracerebral syngeneic glioblastoma models, CRISPR/Cas9 gene knockout of Thrombospondin-1 (TSP-1/Thbs1), a synaptogenic factor critical for glioma-induced neuronal circuit remodeling, in glioblastoma cells suppressed synaptogenesis and glutamatergic neuronal hyperexcitability, while simultaneously restoring antigen-presentation and pro-inflammatory responses. Moreover, TSP-1 knockout prolonged survival of immunocompetent mice harboring intracerebral syngeneic glioblastoma, but not of immunocompromised mice, and promoted infiltrations of pro-inflammatory TAMs and CD8+ T-cells in the tumor microenvironment. Notably, pharmacological inhibition of glutamatergic excitatory signals redirected tumor-associated macrophages toward a less immunosuppressive phenotype, resulting in prolonged survival. Altogether, our results demonstrate previously unrecognized immunosuppression mechanisms resulting from glioma-neuronal circuit remodeling and suggest future strategies targeting glioma-neuron-immune crosstalk may open up new avenues for immunotherapy.

cancer biology↗

bioRxiv2023

Actin-Driven Nanotopography Enhances Integrin Molecular Clutch in Developing Tissue

Morphogenesis requires building stable macromolecular structures from highly dynamic proteins. Muscles are anchored by long-lasting integrin adhesions to resist contractile force. However, the mechanisms governing integrin diffusion, immobilization, and activation within developing tissues remain elusive. Here, we show that actin polymerisation-driven membrane protrusions form nanotopographies that enable strong adhesion at Drosophila muscle attachment sites (MAS). Super-resolution microscopy revealed that integrins assemble adhesive belts around Arp2/3-dependent actin protrusions, forming invadosome-like structures with membrane nanotopographies. Single protein tracking showed that, during MAS development, integrins became immobile and confined within diffusion traps formed by the membrane nanotopographies. Actin filaments also displayed restricted motion and confinement, indicating strong mechanical connection with integrins. Using isolated muscles cells, we show that substrate nanotopography, rather than rigidity, drives adhesion maturation by regulating actin protrusion, integrin diffusion and immobilization. These results thus demonstrate that actin-polymerisation driven membrane protrusions are essential for the formation of strong integrin adhesions sites in the developing embryo, and highlight the important contribution of geometry to morphogenesis.

cell biology↗