Biology subjects

Zhai, J.

Publications and source records attributed to Zhai, J..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Comparative atlas of genome-wide chromatin-associated protein co-occupancy

Accurate transcriptional regulation and chromatin dynamics requires the coordination and activity of chromatin-associated proteins (CAPs) at distinct loci. While the combinatorial activity of a select set of CAPs has been previously examined, these studies are limited by the underrepresentation of proteins and cell types explored, making it difficult to identify the global associations as well as the conservation of these associations across different cell types. Here, we performed 270 CAP chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq) experiments in both K562 and HepG2 cancer cell lines and explored the relationship between cell identity and CAP co-association using three distinct approaches. We employed a machine learning algorithm to organize the genome-wide binding profiles into 56 and 70 interpretable co-association modules for HepG2 and K562 cell lines, respectively. We found CAP co-association modules are mostly cell type-specific, however those present in both cell lines are largely comprised of TFs from a single TF family and anchor to unique loci via lineage-specific factors. While enhancer-associated co-binding modules were largely composed of cell type-specific CAPs, we found regulatory activity at promoter-enhancer module contacts to be enriched for chromatin remodeling proteins. Additionally, we used colocalization information derived from co-association models in conjunction with neural network models of transcription factor (TF) activity to identify high-confidence candidate TF cooperative pairs. Finally, through comparing CAP enrichment in high occupancy target (HOT) regions in K562 and HepG2 cell lines, we found cell type-specific HOT sites, but not common HOT sites, are selectively enriched at high copy number loci. Overall, this study uncovers principles of sequence-level and large-scale CAP genomic organization and demonstrates how this contributes to cell type-specific regulatory mechanisms and cellular functions.

genomics↗

bioRxiv2024

The maize recombination landscape evolved during domestication.

Meiotic recombination is an important evolutionary process because it can increase the amount of genetic variation within populations through the breakage of unfavorable linkages and creation of novel allelic combinations. Despite the plethora of knowledge about population-level benefits of recombination and numerous theoretical studies examining how recombination rates can evolve over time, there is a lack of empirical evidence for any hypotheses that have been put forward. To alleviate this gap in knowledge, we characterized the evolution of the recombination landscape in Zea mays ssp. mays (maize) during its domestication from Zea mays ssp. parviglumis (teosinte), explored hypotheses that permitted the evolution of the maize recombination landscape and tied these alterations to changes in the genetic basis of recombination. Using experimental populations and the population genomics approach of ancestral recombination graph (ARG) inference, our data demonstrated that maize had a 12% increase in its genome-wide recombination rate during domestication. Although the maize and teosinte recombination landscapes are highly correlated, r = 0.85 at 1Mb resolution, maize has evolved to have higher recombining regions in interstitial chromosome regions, compared to teosinte which only harbors high recombining regions sub-telomerically. Our data show that the re-patterning of COs towards interstitial chromosome regions came from reduced CO interference levels within maize. Supporting the idea that CO interference is reduced within maize, we found evidence for selection acting on trans-acting recombination-modifiers that participate in the class I CO pathway or CO interference directly. Lastly, we showed that the re-patterning of COs was beneficial to maize evolution because regions that significantly increased in recombination were targeted to gene-rich regions harboring domestication related loci. Because we found regions with significant increases in recombination had a lower deleterious mutation load, compared to regions with decreases in recombination, we concluded that the domestication-related variation in these regions, in which selection acted upon during domestication, was shielded from the Hill-Robertson effect. In conclusion, the re-patterning of CO events during domestication allowed maize to adapt and evolve at a faster rate than previously understood.

evolutionary biology↗

bioRxiv2024

Deleting PTEN, but not SOCS3 or myelin inhibitors, robustly boosts BRAF-elicited intraspinal regeneration of peripheral sensory axons

Primary sensory axons fail to regenerate into the spinal cord after dorsal root (DR) injury, resulting in persistent sensory deficits. This regenerative failure occurs at the dorsal root entry zone (DREZ), the CNS-PNS interface where injured sensory axons encounter both extrinsic inhibitory cues and a limited intrinsic growth state. Although several approaches have promoted partial DR regeneration across the DREZ, sustained long-distance regeneration, particularly of large-diameter myelinated axons, remains a major challenge. We previously showed that induced expression of constitutively active B-RAF (kaBRAF) increases the regenerative competence of injured adult DRG neurons. Here, we tested whether robust intraspinal regeneration after cervical DR injury could be achieved by selective kaBRAF expression alone or in combination with removal of myelin-associated inhibitors or deletion of neuron-intrinsic growth suppressors, PTEN or SOCS3. kaBRAF promoted reproducible but limited regeneration across the DREZ and did not produce significant functional recovery by two months. Additional deletion of Nogo, MAG, and OMgp produced only a modest improvement in kaBRAF-mediated regeneration. Deletion of PTEN or SOCS3, either alone or together, failed to promote meaningful growth across the DREZ. In contrast, PTEN deletion dramatically enhanced kaBRAF-mediated regeneration, enabling many axons to penetrate the DREZ and grow deep into the spinal cord, whereas SOCS3 deletion provided little additional benefit. These findings identify combined activation of BRAF-MEK-ERK and PI3K-Akt-mTOR signaling as a powerful strategy for stimulating robust intraspinal regeneration of injured DR axons.

neuroscience↗

bioRxiv2024

DeepSME: De Novo Nanopore Basecalling of Motif-insensitive DNA Methylation and Alignment-free Digital Information Decryptions at Single-Molecule Level

Hidden messages in DNA molecules by employing chemical modifications has been suggested for private data storage and transmission at high information density. However, rapidly decoding these "molecular keys" with corresponding basecallers remains challenging. We present DeepSME, a nanopore sequencing and deep-learning based framework towards single-molecule encryption, demonstrated by using 5-hydroxymethylcytosine (5hmC) substitution for individual nucleotide recognition rather than sequential interactions. This non-natural, motif-insensitive methylation disrupts ion current, resulting in a readout failure of 67.2%-100%, concealing the privacy within the DNAs. We further develop an alignment-free DeepSME basecaller as a key to reconstitute the digital information. Our three-stage training pipeline, expands k-mer size from 46 to 49, achieving over 92% precision and recall from scratch. DeepSME deciphers fully 5hmC concealed text and image within 16x coverage depth with an F1-score of 86.4%, surpassing all the state-of-the-art basecallers. Demonstrated on edge computing devices, DeepSME holds supreme potential for DNA-based private communications and broader bioengineering and medical applications.

bioinformatics↗

bioRxiv2024

A transgene-free, human peri-gastrulation embryo model with trilaminar embryonic disc-, amnion- and yolk sac-like structures

The ultimate outcome of the gastrulation in mammalian development is a recognizable trilaminar disc structure containing organized cell lineages with spatially defined identities in an emerging coordinate system1-4. Despite its importance in human development, gastrulation remains difficult to study. Stem cell-based embryo models, including those that recapitulate different aspects of pre- and peri-gastrulation human development5-15, are emerging as promising tools for studying human embryogenesis16-18. However, it remains unclear whether existing human embryo models are capable of modeling the development of the trilaminar embryonic disc structure, a hallmark of human gastrulation. Here we report a transgene-free human embryo model derived solely from primed human pluripotent stem cells (hPSCs), which recapitulates various aspects of peri-gastrulation human development, including formation of trilaminar embryonic layers situated between dorsal amnion and ventral definitive yolk sac and primary hematopoiesis. We term this model the peri-gastrulation trilaminar embryonic disc (PTED) embryoid. The development of PTED embryoid does not follow natural developmental sequences of cell lineage diversification or spatial organization. Instead, it exploits both extrinsic control of tissue boundaries and intrinsic self-organizing properties and embryonic plasticity of the diverse peri-gastrulation-stage cell lineages, leading to the emergence of in vivo-like tissue organization and function at a global scale. Our lineage tracing study reveals that in PTED embryoids, embryonic and extraembryonic mesoderm cells, as well as embryonic and extraembryonic endoderm cells, share common progenitors emerging during peri-gastrulation development. Active hematopoiesis and blood cell generation are evident in the yolk sac-like structure of PTED embryoids. Together, PTED embryoids provide a promising and ethically less challenging model for studying self-organizing properties of peri-gastrulation human development.

developmental biology↗

bioRxiv2024

Composite Hedges Nanopores: A High INDEL-Correcting Codec System for Rapid and Portable DNA Data Readout

DNA, as the origin for the genetic information flow, has also been a compelling alternative to non-volatile information storage medium. Reading digital information from this highly dense but lightweighted medium nowadays relied on conventional next-generation sequencing (NGS), which involves wash and read cycles for synchronization and the indel (insertion and deletion) errors rarely occur. However, these time-consuming cycles hinder the future of real-time data retrieval. Nanopore sequencing holds the promise to overcome the efficiency problem, but high indel error rates lead to the requirement of large amount of high-quality data for accurate readout using emerging NGS-based codec systems. Here we introduce Composite Hedges Nanopores (CHN), a nanopore-based codec scheme tailored for real-time data retrieval, capable of handling indel rates up to 15.9% and substitution rates up to 7.8%. The overall information density can be doubled from 0.59 to 1.17 by utilizing a degenerated eight-letter alphabet, where one composite strand will be projected into eight normal strands. We demonstrate that sequencing times of 20 and 120 minutes were sufficient for processing representative text and image files (7 and 115 composite strands), respectively. The time-diminishing deviations are mainly originated from the extremely uneven abundance among the composite strands (cross-group variation) as well as the huge inequality among the normal strands (in-group variation). Moreover, to achieve complete data recovery, it is estimated that text and image data require 4x and 8x physical redundancy (coverage) of composite strands, respectively. Our CHN codec system excels on both molecular design and equalized dictionary usage, laying a solid foundation for nucleic acid-based data retrieval and encoding approaching to real-time, applicable in both cloud and edge computing systems.

bioinformatics↗

bioRxiv2024

Cross-species plant genomes modeling at single nucleotide resolution using a pre-trained DNA language model

Interpreting function and fitness effects in diverse plant genomes requires transferable models. Language models (LMs) pre-trained on large-scale biological sequences can learn evolutionary conservation and offer cross-species prediction better than supervised models through fine-tuning limited labeled data. We introduce PlantCaduceus, a plant DNA LM based on the Caduceus and Mamba architectures, pre-trained on a curated dataset of 16 Angiosperm genomes. Fine-tuning PlantCaduceus on limited labeled Arabidopsis data for four tasks, including predicting translation initiation/termination sites and splice donor and acceptor sites, demonstrated high transferability to 160 million year diverged maize, outperforming the best existing DNA LM by 1.45 to 7.23-fold. PlantCaduceus is competitive to state-of-the-art protein LMs in terms of deleterious mutation identification, and is threefold better than PhyloP. Additionally, PlantCaduceus successfully identifies well-known causal variants in both Arabidopsis and maize. Overall, PlantCaduceus is a versatile DNA LM that can accelerate plant genomics and crop breeding applications.

bioinformatics↗

bioRxiv2024

Computation-aided Design of Rod-Shaped Janus Base Nanopieces for Improved Tissue Penetration and Therapeutics Delivery

Despite the development of various drug delivery technologies, there remains a significant need for vehicles that can improve targeting and biodistribution in "hard-to-penetrate" tissues. Some solid tumors, for example, are particularly challenging to penetrate due to their dense extracellular matrix (ECM). In this study, we have formulated a new family of rod-shaped delivery vehicles named Janus base nanopieces (Rod JBNps), which are more slender than conventional spherical nanoparticles, such as lipid nanoparticles (LNPs). These JBNp nanorods are formed by bundles of DNA-inspired Janus base nanotubes (JBNts) with intercalated delivery cargoes. To develop this novel family of delivery vehicles, we employed a computation-aided design (CAD) methodology that includes molecular dynamics and response surface methodology. This approach precisely and efficiently guides experimental designs. Using an ovarian cancer model, we demonstrated that JBNps markedly improve penetration into the dense ECM of solid tumors, leading to better treatment outcomes compared to FDA-approved spherical LNP delivery. This study not only successfully developed a rod-shaped delivery vehicle for improved tissue penetration but also established a CAD methodology to effectively guide material design.

bioengineering↗

bioRxiv2023

A Day in the Life of Arabidopsis: 24-Hour Time-lapse Single-nucleus Transcriptomics Reveal Cell-type specific Circadian Rhythms

Functional circadian clock is fundamental to the adaptation and survival of organisms. In land plants, the comprehensive profiling of circadian gene expression at the single-cell level is largely unknown partly due to the challenges in obtaining precisely-timed single cells from plant cells embedded within cell walls. To bridge this gap, we employed single-nucleus RNA sequencing (snRNA-seq) on twelve seedling samples collected at 2-hour intervals over a 24-hour day in Arabidopsis, yielding a total of over 130,000 nuclei. From this data, we found that three cell clusters in the shoot share a coherent rhythm, while more than 3,000 genes display cell-type specific rhythmic expression. Only 19 genes are oscillating in more than ten different cell types, and the majority of them are well-documented core oscillators, suggesting the snRNA-seq circadian data could be used to identify key circadian regulators in a broad range of plant systems. Our data provides the first comprehensive resource for plant circadian rhythms at the single-cell level (hosted at https://zhailab.bio.sustech.edu.cn/sc_circadian).

plant biology↗

bioRxiv2023

Fishing for a reelGene: evaluating gene models with evolution and machine learning

Assembled genomes and their associated annotations have transformed our study of gene function. However, each new assembly generates new gene models. Inconsistencies between annotations likely arise from biological and technical causes, including pseudogene misclassification, transposon activity, and intron retention from sequencing of unspliced transcripts. To evaluate gene model predictions, we developed reelGene, a pipeline of machine learning models focused on (1) transcription boundaries, (2) mRNA integrity, and (3) protein structure. The first two models leverage sequence characteristics and evolutionary conservation across related taxa to learn the grammar of conserved transcription boundaries and mRNA sequences, while the third uses conserved evolutionary grammar of protein sequences to predict whether a gene can produce a protein. Evaluating 1.8 million gene models in maize, reelGene found that 28% were incorrectly annotated or nonfunctional. By leveraging a large cohort of related species and through learning the conserved grammar of proteins, reelGene provides a tool for both evaluating gene model accuracy and genome biology.

genomics↗

bioRxiv2023

The longitudinal single-cell panorama of cynomolgus monkey ovary throughout lifespan revealed a conserved ovarian clock between primates

Ovarian function is critical for female fertility and impacts reproductive longevity. It is of great importance to accurately predict the aging process within the ovary for fertility assessment and disease diagnosis. However, cell metrics for evaluating the ovarian aging rate are still in urgent need, and molecular insights into ovarian development and dysfunction during the primate life course are also limited. Here, we reported large-scale ovarian cell atlas of consecutive development of cynomolgus monkeys across 22 years with 20 time points, covering the foetal, newborn, prepubertal, pubertal, adult, perimenopausal and menopausal stages. We characterized and validated distinct molecular signatures of each cluster of cells within primate ovaries, and uncovered a previously undocumented RHOXF1-positive oocyte type during primordial follicle assembly in primates. Furthermore, the constitution and developmental trajectories of primate germ cells, granulosa cells and stromal / theca cells were also elucidated, and their precursors were identified. More importantly, dynamics of cellular compositions were unravelled through the ovarian development, featured by granulosa, epithelial, stromal, and immune cells that showed strong temporal heterogeneity spanning lifetime, whilst referred to the key function during the corresponding stages. Based on the correlations of each cell type with age and stage-specific molecular dynamics, we further constructed a transcriptomic ovarian clock which could perceive an effective biological age prediction of the ovary and further applied to humans. The findings reveal granulosa, epithelial, and stromal cells as the highest performance predictors of ovarian biological age, while highlighting the crucial role of AGE-RAGE and Relaxin signaling pathways in regulating ovarian aging. Our work not only provide valuable resource for obtaining insights into the development, aging and dysfunction of key organs, but also establish a transcriptomic clock to predict biological ovarian aging thus to be potential clinical implementation in future.

developmental biology↗

bioRxiv2023

Comparative single-nucleus RNA-seq analysis captures shared and distinct responses to beneficial and pathogenic microbes in roots

Distinguishing and differentially responding to beneficial and pathogenic microbes are fundamental for plants to maintain microbiome homeostasis and promoting plant fitness. Using a recently developed protoplast-free single-nucleus RNA-seq approach, we generated single-cellular atlas of root responses to beneficial and pathogenic microbes. Notably, we identified triterpene biosynthesis as a novel cell type specific response to root pathogens and genetically confirmed the role of triterpene biosynthesis in regulating beneficial/pathogenic microbe ratios in a two-strain mixed community. Our results provide novel insights and vital resources for further elucidating novel regulators of beneficial and pathogenic microbe colonization and microbiome homeostasis.

plant biology↗

bioRxiv2022

Effects of canagliflozin and irbesartan on renal fibrosis in Dahl salt-sensitive rats

Hypertension is one of the major contributors to cardiovascular and chronic kidney disease (CKD). Sodium-glucose cotransporter 2 (SGLT2) inhibitors and angiotensin receptor blockers (ARBs) have become the preferred treatment for patients with CKD. However, the renoprotective effects of the combined therapy of the two drugs on hypertensive renal fibrosis are still largely understood. The aim of this study was to compare the antifibrotic effects of canagliflozin, with or without irbesartan, in the kidneys of Dahl salt-sensitive (Dahl SS) rats on a high salt (HS) diet. After the preconditioning stage, Dahl SS rats (n = 47) were divided into 5 experimental groups as follows: low salt control (n=7), HS control (n=10), high salt with canagliflozin (n=10), high salt with irbesartan (n=10), and high salt with canagliflozin plus irbesartan (n=10). Mean food and water intake, body weight (BW), and systolic blood pressure (SBP) were measured during the whole experimental period. After 12 weeks, the rats were euthanized, and the kidneys were excised for histomorphometric evaluation and immunohistochemical evaluation. An HS diet increased SBP, renal fibrosis, expression of fibrotic protein factors, and TGF-{beta}/Smad2/3 pathway compared to the LS group. We found that irbesartan reduced SBP and slowed the loss of renal function. Canagliflozin significantly reduced BW and renal fibrosis and downregulated the TGF-{beta}/Smad2/3 pathway. The combined therapy showed better renoprotection in all outcome parameters. In conclusion, these results indicate that canagliflozin and irbesartan exert different benefits on nephroprotection in salt-sensitive hypertensive rats.

molecular biology↗

bioRxiv2022

Synapsing with oligodendrocyte precursor cells stop sensory axons regenerating into the spinal cord

Primary sensory axons stop regenerating as they re-enter the spinal cord, resulting in incurable sensory loss. What arrests them has remained unclear. We previously showed that axons stop by forming synaptic contacts with unknown non-neuronal cells. Here, we identified these cells in adult mice as oligodendrocyte precursor cells (OPCs). We also found that only a few axons stop regenerating by forming dystrophic endings, exclusively at the CNS:PNS borderline where OPCs are absent. Most axons stop in contacts with a dense network of OPC processes. Live imaging, immuno-EM and OPC-DRG co-culture additionally suggest that axons are rapidly immobilized by forming synapses with OPCs. Genetic OPC ablation enables many axons to continue regenerating deep into the spinal cord. We propose that sensory axons stop regenerating by encountering OPCs that induce presynaptic differentiation. Our findings identify OPCs as a major regenerative barrier that prevents intraspinal restoration of sensory circuits following spinal root injury.

neuroscience↗

bioRxiv2022

FOXP2 confers oncogenic effects in prostate cancer through activating MET signalling

Identification oncogenes is fundamental to revealing the molecular basis of cancer. Here, we found that FOXP2 is overexpressed in human prostate cancer cells and prostate tumors, but its expression is absent in normal prostate epithelial cells and low in benign prostatic hyperplasia. To date, little is known regarding the link of FOXP2 to prostate cancer. We observed that high FOXP2 expression and frequent amplification are significantly associated with high Gleason score. Ectopic expression of FOXP2 induces malignant transformation of mouse NIH3T3 fibroblasts and human prostate epithelial cell RWPE-1. Conversely, FOXP2 knockdown suppresses the proliferation of prostate cancer cells. Transgenic overexpression of FOXP2 in the mouse prostate causes prostatic intraepithelial neoplasia. Overexpression of FOXP2 aberrantly activates oncogenic MET signalling and inhibitors targeting MET signalling effectively reverts the FOXP2-induced oncogenic phenotype. Additionally, the novel recurrent FOXP2-CPED1 fusion identified in prostate tumors results in high expression of truncated FOXP2, which exhibit a similar capacity for malignant transformation. Together, our data demonstrate for the first time that FOXP2 is an oncogene involved in tumorigenicity of prostate.

cancer biology↗

bioRxiv2022

Integrated single-nucleus and spatial transcriptomics captures transitional states in soybean nodule symbiosis establishment

Legumes form symbiosis with rhizobium leading to the development of nitrogen-fixing nodules. By integrating single-nucleus and spatial transcriptomics, we established a cell atlas of soybean nodules and roots. In central infected zone of nodule, we found that uninfected cells specialize into functionally distinct sub-groups during nodule development and revealed a transitional subtype of infected cells with enriched nodulation-related genes. Overall, our results provide a single-cell perspective for understanding rhizobium-legume symbiosis.

plant biology↗

bioRxiv2022

Plant Intron Splicing Efficiency Database (PISE): exploring splicing of ~1,650,000 introns in Arabidopsis, maize, rice and soybean from ~57,000 public RNA-seq libraries

Intron retention is the most common form of alternative splicing events in plants and plays a crucial role in plants responding to environmental signals. Despite a large number of RNA-seq libraries from different treatments and genetic mutants stored at public domains, a resource for querying the intron splicing ratio of individual introns is still missing. Here, we established the first-ever large-scale splicing efficiency database to date in any organism. Our database includes more than 57,000 plant public RNA-seq libraries, including 25,283 from Arabidopsis, 17,789 from maize, 10,710 from rice, and 3,974 from soybean, and in total covers more than 1.6 million introns in these four species. In addition, we have manually curated and annotated all the mutant-and treatment-related libraries as well as their matched controls included in our library collection, and added graphics to display intron splicing efficiency across different tissues, developmental stages, and stress-related conditions. The result is a large collection of 3,313 treatment conditions and 3,594 genetic mutants for discovering the differentially regulated splicing efficiency. Our online database can be accessed at https://plantintron.com/.

plant biology↗

bioRxiv2022

MCIBox: A Toolkit for Single-molecule Multi-way Chromatin Interaction Visualization and Micro-Domains Identification

The emerging ligation-free three-dimensional (3D) genome mapping technologies can identify multiplex chromatin interactions with single-molecule precision. These technologies offer new insight into high-dimensional chromatin organization and gene regulation, but also introduce new challenges in data visualization and analysis. To overcome these challenges, we developed MCIBox, a toolkit for Multi-way Chromatin Interaction (MCI) analysis, including a visualization tool and a platform for identifying micro-domains with clustered single-molecule chromatin complexes. MCIBox is based on various clustering algorithms integrated with dimensionality reduction methods that can display multiplex chromatin interactions at single-molecule level, allowing users to explore chromatin extrusion patterns and super-enhancers regulation modes in transcription, and to identify single-molecule chromatin complexes that are clustered into micro-domains. Furthermore, MCIBox incorporates a two-dimensional kernel density estimation algorithm to identify micro-domains boundaries automatically. These micro-domains were stratified with distinctive signatures of transcription activity and contained different cell cycle associated genes. MCIBox could potentially distinguish the specificity of single-molecule chromatin interaction patterns in various phases of a cell cycle or cell types.

genomics↗