Biology subjects

Ma, J.

Publications and source records attributed to Ma, J..

At least 217 records · Page 12Linked to original sources

bioRxiv2023

Nucleolus and centromere TSA-Seq reveals variable localization of heterochromatin in different cell types

Genome differential positioning within interphase nuclei remains poorly explored. We extended and validated TSA-seq to map genomic regions near nucleoli and pericentric heterochromatin in four human cell lines. Our study confirmed that smaller chromosomes localize closer to nucleoli but further deconvolved this by revealing a preference for chromosome arms below 36-46 Mbp in length. We identified two lamina associated domain subsets through their differential nuclear lamina versus nucleolar positioning in different cell lines which showed distinctive patterns of DNA replication timing and gene expression across all cell lines. Unexpectedly, active, nuclear speckle-associated genomic regions were found near typically repressive nuclear compartments, which is attributable to the close proximity of nuclear speckles and nucleoli in some cell types, and association of centromeres with nuclear speckles in hESCs. Our study points to a more complex and variable nuclear genome organization than suggested by current models, as revealed by our TSA-seq methodology.

cell biology↗

bioRxiv2023

Human CD127 negative ILC2s show immunological memory

Group 2 Innate Lymphoid Cells (ILC2s) serve as key players in type 2 immunity and contribute significantly to maintaining homeostasis and responding to inflammation. Notably, ILC2s are closely implicated in the development of allergic disorders like asthma. While previous research has demonstrated immunological memory in mouse ILC2s, it has remained unclear whether human ILC2s can acquire this form of memory. In this study, we demonstrate the persistence of CD45RO, a marker previously linked to inflammatory ILC2s, in resting ILC2s that have undergone prior activation. These cells concurrently reduce the expression of the canonical ILC marker CD127. Through in vitro experiments involving the isolation and stimulation of CD127-CD45RO+ ILC2s, we observed an augmented ability to produce cytokines and undergo proliferation. CD127-CD45RO+ ILC2s are found in both healthy and inflamed tissues and display a gene signature of cell activation. Memory ILC2s may play a significant role in chronic type 2 diseases, such as allergic asthma and atopic dermatitis. HIGHLIGHTS- Inflamed and healthy tissues contain CD127-ILC2s with a gene signature of cell activation - CD127-CD45RO+ ILC2s from healthy tissues show immunological memory features - Mouse memory ILC2s downregulate CD127 - In vitro stimulation of naive ILC2s generates memory CD127-CD45RO+ ILC2s

immunology↗

bioRxiv2023

SART1 localizes to spindle poles forming a SART1 cap and promotes spindle pole assembly

The nuclear protein SART1 has been associated with pre-mRNA splicing but SART1 RNAi knockdown results also in defects in mitotic progression, centrosome biogenesis and chromosome cohesion. The mitotic roles of SART1 have not been characterized in detail and it remains unclear whether SART1 functions in mitosis directly or indirectly via pre-mRNA splicing. Here, we identify SART1 as a direct, mitosis-specific microtubule-associated protein. SART1 downregulation in human cells leads to spindle assembly defects with reduced microtubule dynamics, lack of end-on attachment, and checkpoint activation, while microtubule dynamics remain unaffected in interphase. SART1 uniquely localizes to the distal surface of mitotic centrosomes along the spindle axis, forming a previously not described structure we refer to as SART1 cap. Immunoprecipitation of SART1 consistently identifies centrosomal proteins as interaction partners. Immunostaining of these shows that SART1 downregulation does not affect centriole duplication and centrosome-accumulation of {gamma}-tubulin but reduces the accumulation of selective pericentriolar material (PCM) proteins like Ninein. Depletion of SART1 from frog egg extracts disrupts spindle pole assembly around sperm nuclei and DNA-coated beads. Spindles formed around DNA-coated beads do not contain centrosomes but still recruits PCM proteins for spindle pole assembly. We finally show that the N-terminus of SART1 is its microtubule-binding region and essential for spindle assembly. Our data unravel a unique localization of SART1 and a novel function to recruit selective PCM proteins for spindle pole assembly in centrosomal and acentrosomal spindle assembly.

cell biology↗

bioRxiv2023

OPUS-Rota5: A Highly Accurate Protein Side-chain Modeling Method with 3D-Unet and RotaFormer

Accurate protein side-chain modeling is crucial for protein folding and design. This is particularly true for molecular docking as ligands primarily interact with side chains. A protein structure with large errors in side chains has limited usage such as in drug design. Previous research on AlphaFold2 (AF2) predictions of GPCR targets indicates that the docking of natural ligands back on AF2-predicted structures has limited successful rate presumably due to large errors in side chains. Here, we introduce a two-stage side-chain modeling approach called OPUS-Rota5. It leverages a modified 3D-Unet to capture the local environmental features including ligand information of each residue, and then employs RotaFormer module to aggregate various types of feature. Evaluation on three test sets, including recently released targets from CAMEO and CASP15, reveals that side chains modeled by OPUS-Rota5 are significantly more accurate than those predicted by other methods. We also employ OPUS-Rota5 to refine the side chains of 25 GPCR targets predicted by AF2 and then performed docking of their natural ligands back with a significantly improved successful rate. Such results suggest that OPUS-Rota5 could be a valuable tool for molecular docking, particularly for targets with relatively accurate predicted backbones, but not side chains.

bioinformatics↗

bioRxiv2023

CellContrast: Reconstructing Spatial Relationships in Single-Cell RNA Sequencing Data via Deep Contrastive Learning

A vast amount of single-cell RNA-seq (SC) data has been accumulated via various studies and consortiums, but the lack of spatial information limits its analysis of complex biological activities. To bridge this gap, we introduce cellContrast, a computational method for reconstructing spatial relationships among SC cells from spatial transcriptomics (ST) reference. By adopting a contrastive learning framework and training with ST data, cellContrast projects gene expressions into a hidden space where proximate cells share similar representation values. We performed extensive benchmarking on diverse platforms, including SeqFISH, Stereo-Seq, 10X Visium, and MERSCOPE, on mouse embryo and human breast cells. The results reveal that cellContrast substantially outperforms other related methods, facilitating accurate spatial reconstruction of SC. We further demonstrate cellContrasts utility by applying it to cell-type co-localization and cell-cell communication analysis with real-world SC samples, proving the recovered cell locations empower novel discoveries and mitigate potential false positives.

bioinformatics↗

bioRxiv2023

PhyGCN: Pre-trained Hypergraph Convolutional Neural Networks with Self-supervised Learning

Hypergraphs are powerful tools for modeling complex interactions across various domains, including biomedicine. However, learning meaningful node representations from hypergraphs remains a challenge. Existing supervised methods often lack generalizability, thereby limiting their real-world applications. We propose a new method, Pre-trained Hypergraph Convolutional Neural Networks with Self-supervised Learning (PhyGCN), which leverages hypergraph structure for self-supervision to enhance node representations. PhyGCN introduces a unique training strategy that integrates variable hyperedge sizes with self-supervised learning, enabling improved generalization to unseen data. Applications on multi-way chromatin interactions and polypharmacy side-effects demonstrate the effectiveness of PhyGCN. As a generic framework for high-order interaction datasets with abundant unlabeled data, PhyGCN holds strong potential for enhancing hypergraph node representations across various domains.

bioinformatics↗

bioRxiv2023

Unravelling cancer subtype-specific driver genes in single-cell transcriptomics data with CSDGI

Cancer is known as a heterogeneous disease. Cancer driver genes (CDGs) need to be inferred for understanding tumor heterogeneity in cancer. However, the existing computational methods have identified many common CDGs. A key challenge exploring cancer progression is to infer cancer subtype-specific driver genes (CSDGs), which provides guidane for the diagnosis, treatment and prognosis of cancer. The significant advancements in single-cell RNA-sequencing (scRNA-seq) technologies have opened up new possibilities for studying human cancers at the individual cell level. In this study, we develop a novel unsupervised method, CSDGI (Cancer Subtype-specific Driver Gene Inference), which applies Encoder-Decoder-Framework consisting of low-rank residual neural networks to inferring driver genes corresponding to potential cancer subtypes at single-cell level. To infer CSDGs, we apply CSDGI to the tumor single-cell transcriptomics data. To filter the redundant genes before driver gene inference, we perform the differential expression genes (DEGs). The experimental results demonstrate CSDGI is effective to infer driver genes that are cancer subtype-specific. Functional and disease enrichment analysis shows these inferred CSDGs indicate the key biological processes and disease pathways. CSDGI is the first method to explore cancer driver genes at the cancer subtype level. We believe that it can be a useful method to understand the mechanisms of cell transformation driving tumours. Author summaryCancer is recognized as a complex disease with diverse characteristics. In order to comprehend the diversity within tumors, it is essential to infer cancer subtype-specific driver genes (CSDGs), which offer valuable insights for investigating cancer progression and treatment. The remarkable progress made in single-cell RNA-sequencing (scRNA-seq) technologies has ushered in new prospects for studying human cancers at the cellular level. Cancer Subtype-specific Driver Gene Inference (CSDGI) is a novel unsupervised method proposed. In our study, we use Encoder-Decoder-Framework to infer driver genes specific to cancer subtypes in the CSDGI. We apply CSDGI to three tumor single-cell transcriptomics data. The experimental results have shown the effectiveness of CSDGI. Furthermore, functional and disease enrichment analyses illustrate that these inferred CSDGs shed light on crucial biological processes and disease pathways. Our collection of driver genes will serve as a valuable resource in unraveling the mechanisms driving cell transformation in tumors.

bioinformatics↗

bioRxiv2023

Longer mandible or nose? Co-evolution of feeding organs in early elephantiforms

The long-trunked elephantids underwent a significant evolutionary stage characterized by an exceptionally elongated mandible. The initial elongation and subsequent regression of the long mandible, along with its co-evolution with the trunk, present an intriguing issue that remains incompletely understood. Through comparative functional and eco-morphological investigations, as well as feeding preference analysis, we reconstructed the feeding behavior of major groups of longirostrine elephantiforms. In the Platybelodon clade, the rapid evolutionary changes observed in the narial region, strongly correlated with mandible and tusk characteristics, suggest a crucial evolutionary transition where feeding function shifted from the mandible to the trunk, allowing proboscideans to expand their niches to more open regions. This functional shift further resulted in elephantids relying solely on their trunks for feeding. Our research provides insights into how unique environmental pressures shape the extreme evolution of organs, particularly in large mammals that developed various peculiar adaptations during the late Cenozoic global cooling trends.

paleontology↗

bioRxiv2023

Enhancing CRISPR prime editing by reducing misfolded pegRNA interactions

CRISPR prime editing (PE) requires a Cas9 nickase-reverse transcriptase fusion protein (known as PE2) and a prime editing guide RNA (pegRNA), an extended version of a standard guide RNA (gRNA) that both specifies the intended target genomic sequence and encodes the desired genetic edit. Here we show that sequence complementarity between the 5 and the 3 regions of a pegRNA can negatively impact its ability to complex with Cas9, thereby potentially reducing PE efficiency. We demonstrate this limitation can be overcome by a simple pegRNA refolding procedure, which improved ribonucleoprotein-mediated PE efficiencies in zebrafish embryos by up to nearly 25-fold. Further gains in PE efficiencies of as much as 6-fold could also be achieved by introducing point mutations designed to disrupt internal interactions within the pegRNA. Our work defines simple strategies that can be implemented to improve the efficiency of PE.

genomics↗

bioRxiv2023

Biogenic phosphonate utilization by globally distributed diatom Thalassiosira

Phosphonate is a class of enigmatic organic phosphorus compounds that contribute [~]25% of total dissolved organic phosphorus (DOP). Recent studies reveal the important role of phosphonate mediated by prokaryotes in the marine P redox cycle, however, its bioavailability and metabolic process by eukaryotic phytoplankton are under debate. 2-Aminoethylphosphonic acid and (2-AEP) and 2-amino-3-phosphonopropionic acid (2-AP3) are two biogenic phosphonates that ubiquitously exist in marine environment. Here, we report that Thalassiosira pseudonana, a dominant diatom species in the ocean, are able to recover growth from phosphorus starvation with individual supplement of 2-AEP and 2-AP3. Moreover, the cellular stoichiometric C:P and N:P ratios of cells grown under 2-AEP are in-between the P-depleted and DIP-replete groups. This study provided evidence that biogenic phosphonates can be adopted as alternative phosphorus sources to support diatom growth and might have a profound effect on the elemental stoichiometry in the oligotrophic ocean. Scientific significance statementPhosphorus (P) is a major limiting macronutrient for primary productivity in the ocean, whilst the biologically mediated cycling of different P forms is less understood compared to carbon and nitrogen. Accounting for 25% of the marine dissolved organic phosphorus pool, phosphonate bioavailability by eukaryotic phytoplankton still remains discrepancies. In line with our hypothesis, here we report that a cosmopolitan diatom Thalassiosira pseudonana can utilize biogenic phosphonates 2-aminoethylphosphonic acid and 2-amino-3-phosphonopropionic acid to support cell growth, with deviated cellular C:N:P in comparison to that of P-replete cells. Furthermore, cells grown under lower temperature exhibit physiological adaptation (K-selection strategy) with the benefit of 2-AEP supplied in the medium. We provide the evidence that utilization of biogenic phosphonate is ubiquitous in diatom and it might have profound effect on elemental stoichiometry ratios in the environment. Filling in this missing puzzle piece provides us with a fresh perspective to elucidate the role of phosphonates in marine phosphorus cycle and biological pump.

ecology↗

bioRxiv2023

Concurrent profiling of multiscale 3D genome organization and gene expression in single mammalian cells

The organization of mammalian genomes within the nucleus features a complex, multiscale three-dimensional (3D) architecture. The functional significance of these 3D genome features, however, remains largely elusive due to limited single-cell technologies that can concurrently profile genome organization and transcriptional activities. Here, we report GAGE-seq, a highly scalable, robust single-cell co-assay that simultaneously measures 3D genome structure and transcriptome within the same cell. Employing GAGE-seq on mouse brain cortex and human bone marrow CD34+ cells, we comprehensively characterized the intricate relationships between 3D genome and gene expression. We found that these multiscale 3D genome features collectively inform cell type-specific gene expressions, hence contributing to defining cell identity at the single-cell level. Integration of GAGE-seq data with spatial transcriptomic data revealed in situ variations of the 3D genome in mouse cortex. Moreover, our observations of lineage commitment in normal human hematopoiesis unveiled notable discordant changes between 3D genome organization and gene expression, underscoring a complex, temporal interplay at the single-cell level that is more nuanced than previously appreciated. Together, GAGE-seq provides a powerful, cost-effective approach for interrogating genome structure and gene expression relationships at the single-cell level across diverse biological contexts.

genomics↗

bioRxiv2023

Replication Protein A1 is essential for DNA damage repair during mammalian oogenesis

Persistence of unrepaired DNA damage in oocytes is detrimental and may cause genetic aberrations, miscarriage, and infertility. RPA, an ssDNA-binding complex, is essential for various DNA-related processes. Here we report that RPA plays a novel role in DNA damage repair during postnatal oocyte development after meiotic recombination. To investigate the role of RPA during oogenesis, we inactivated RPA1 (replication protein A1), the largest subunit of the heterotrimeric RPA complex, specifically in oocytes using two germline-specific Cre drivers (Ddx4-Cre and Zp3-Cre). We find that depletion of RPA1 leads to the disassembly of the RPA complex, as evidenced by the absence of RPA2 and RPA3 in RPA1-deficient oocytes. Strikingly, severe DNA damage occurs in RPA1-deficient GV-stage oocytes. Loss of RPA in oocytes triggered the canonical DNA damage response mechanisms and pathways, such as activation of ATM, ATR, DNA-PK, and p53. In addition, the RPA deficiency causes chromosome misalignment at metaphase I and metaphase II stages of oocytes, which is consistent with altered transcript levels of genes involved in cytoskeleton organization in RPA1-deficient oocytes. Absence of the RPA complex in oocytes severely impairs folliculogenesis and leads to a significant reduction in oocyte number and female infertility. Our results demonstrate that RPA plays an unexpected role in DNA damage repair during mammalian folliculogenesis.

developmental biology↗

bioRxiv2023

ASD mutation of Katnal2 impairs ependymal ciliary motion and causes hydrocephalus

Katanin catalytic subunit A1 like 2 (KATNAL2) is a high-risk gene associated with autism spectrum disorders (ASD), however its impact on brain development and disease remains unclear. The present study revealed an unexpected role of KATNAL2 in regulating ependymal ciliary motion and cerebrospinal fluid flow during brain development, an important contributing factor for ASD. We discovered a distinct expression pattern of KATNAL2 in multiciliated ependymal cells of both human and mouse brains. Notably, an ASD-associated mutation of Katnal2 disrupted its molecular function and resulted in ASD-related behavioral deficits in mice. Additionally, this mutation affected the polarized organization and beating of ependymal cilia, leading to delayed cerebrospinal fluid flow and sustained ventricular enlargement from the early postnatal stage. Conditional ablation of Katnal2 specifically in the ependymal cells of neonatal mice is sufficient to cause ventricular dilation, whereas no such effect was observed in adult mice. Our findings highlight the importance of ependymal motile cilia and hydrocephalus in ASD, offering insights into its pathogenesis and potential intervention.

neuroscience↗

bioRxiv2023

Structure and engineering of miniature Acidibacillus sulfuroxidans Cas12f1

The miniature CRISPR-Cas12f nucleases allow for efficient delivery via cargo-size-limited adeno-associated virus delivery vehicles, thereby showing promising potential for in vivo therapeutic applications. Acidibacillus sulfuroxidans Cas12f1 (AsCas12f1, 422 amino acids) is the most compact Cas12f nuclease identified to date, showing a moderate level of genome-editing activity in human cells compared to Cas9 and Cas12a. Understanding the mechanisms of why such a compact nuclease is active for genome editing would facilitate its rational engineering. Here, we report the cryo-EM structure of the AsCas12f1-sgRNA-dsDNA ternary complex, and reveal that AsCas12f1 functions as an asymmetric dimer for single-guide RNA (sgRNA) binding and DNA targeting. The detailed mechanisms for dimer formation, PAM recognition, and sgRNA accommodation are elucidated. Leading by the structural knowledge, we extensively engineer the AsCas12f1 nuclease and its corresponding sgRNA, resulting in an evolved AsCas12f1-sgRNA combination with drastically enhanced genome editing activity in human cells. These results provide further understanding of compact CRISPR systems and expand the mini CRISPR toolbox for therapeutic applications.

molecular biology↗

bioRxiv2023

Rapid Prototyping of Thermoplastic Microfluidic 3D Cell Culture Devices by Creating Regional Hydrophilicity Discrepancy

Microfluidic three-dimensional cell culture devices that enable the recapitulation of key aspects of organ structures and functions in vivo represent a promising preclinical platform to improve translational success during drug discovery. Essential to these engineered devices is the spatial patterning of cells from different tissue types within a confined microenvironment. Traditional fabrication strategies lack the scalability, cost-effectiveness, and rapid prototyping capabilities required for industrial applications, especially for processes involving thermoplastic materials. Here, we introduce an approach to pattern fluid guides inside microchannels by establishing differential hydrophilicity using pressure-sensitive adhesives as masks and a subsequent selective coating with a biocompatible polymer. We identified optimal coating conditions using polyvinylpyrrolidone, which resulted in rapid and consistent hydrogel flow in both the open-chip prototype and the fully bonded device containing additional features for medium perfusion. We tested the suitability of our device for dynamic 3D cell culture by growing human hepatocytes in the device under controlled fluid flow for a 14-day period. Additionally, we demonstrated the potential of using our device for pharmaceutical high-throughput screening applications, such as predicting drug-induced liver injury. Our approach offers a facile strategy of rapid prototyping thermoplastic microfluidic organ chips with varying geometries, microstructures, and substrate materials.

bioengineering↗

bioRxiv2023

Tonic Meningeal Interleukin-10 Upregulates Delta Opioid Receptor to Prevent Relapse to Pain

Chronic pain often alternates between transient remission and relapse of severe pain. While most research on chronic pain has focused on mechanisms maintaining pain, there is a critical unmet need to understand what prevents pain from re-emerging in those who recover from acute pain. We found that interleukin (IL)-10, a pain resolving cytokine, is persistently produced by resident macrophages in the spinal meninges during remission from pain. IL-10 upregulated expression and analgesic activity of {delta}-opioid receptor ({delta}OR) in the dorsal root ganglion. Genetic or pharmacological inhibition of IL-10 signaling or {delta}OR triggered relapse to pain in both sexes. These data challenge the widespread assumption that remission of pain is simply a return to the naive state before pain was induced. Instead, our findings strongly suggest a novel concept that: remission is a state of lasting pain vulnerability that results from a long-lasting neuroimmune interactions in the nociceptive system.

neuroscience↗

bioRxiv2023

Large Scale Foundation Model on Single-cell Transcriptomics

Large-scale pretrained models have become foundation models leading to breakthroughs in natural language processing and related fields. Developing foundation models in life science for deciphering the "languages" of cells and facilitating biomedical research is promising yet challenging. We developed a large-scale pretrained model scFoundation with 100M parameters for this purpose. scFoundation was trained on over 50 million human single-cell transcriptomics data, which contain high-throughput observations on the complex molecular features in all known types of cells. scFoundation is currently the largest model in terms of the size of trainable parameters, dimensionality of genes and the number of cells used in the pre-training. Experiments showed that scFoundation can serve as a foundation model for single-cell transcriptomics and achieve state-of-the-art performances in a diverse array of downstream tasks, such as gene expression enhancement, tissue drug response prediction, single-cell drug response classification, and single-cell perturbation prediction.

bioinformatics↗

bioRxiv2023

scGHOST: Identifying single-cell 3D genome subcompartments

New single-cell Hi-C (scHi-C) technologies enable probing of the genome-wide cell-to-cell variability in 3D genome organization from individual cells. Several computational methods have been developed to reveal single-cell 3D genome features based on scHi-C data, including A/B compartments, topologically-associating domains, and chromatin loops. However, no scHi-C analysis method currently exists for annotating single-cell subcompartments, which are crucial for providing a more refined view of large-scale chromosome spatial localization in single cells. Here, we present SCGHOST, a single-cell subcompartment annotation method based on graph embedding with constrained random walk sampling. Applications of SCGHOST to scHi-C data and single-cell 3D genome imaging data demonstrate the reliable identification of single-cell subcompartments and offer new insights into cell-to-cell variability of nuclear subcompartments. Using scHi-C data from the human prefrontal cortex, SCGHOST identifies cell type-specific subcompartments that are strongly connected to cell type-specific gene expression, suggesting the functional implications of single-cell subcompartments. Overall, SCGHOST is an effective new method for single-cell 3D genome subcompartment annotation based on scHi-C data for a broad range of biological contexts.

bioinformatics↗