Biology subjects

Zheng, Z.

Publications and source records attributed to Zheng, Z..

At least 127 records · Page 7Linked to original sources

bioRxiv2023

Cryo-EM structure of the Spo11 core complex bound to DNA

The DNA double-strand breaks that initiate meiotic recombination are formed by topoisomerase relative Spo11, supported by conserved auxiliary factors. Because high-resolution structural data are lacking, many questions remain about the architecture of Spo11 and its partners and how they engage with DNA. We report cryo-EM structures at up to 3.3 [A] resolution of DNA-bound core complexes of Saccharomyces cerevisiae Spo11 with Rec102, Rec104, and Ski8. In these structures, monomeric core complexes make extensive contacts with the DNA backbone and with the recessed 3-OH and first 5 overhanging nucleotide, definitively establishing the molecular determinants of DNA end-binding specificity and providing insight into DNA cleavage preferences in vivo. The structures of individual subunits and their interfaces, supported by functional data in yeast, provide insight into the role of metal ions in DNA binding and uncover unexpected structural variation in homologs of the Top6BL component of the core complex.

biochemistry↗

bioRxiv2023

Protein Language Model Supervised Precise and Efficient Protein Backbone Design Method

Proteins perform essential roles in numerous biological processes, largely driven by the three-dimensional structure of several key motif residues. Recently, a variety of energy-based and machine learning backbone generation methods have been developed to solve the motif-scaffolding task. However, it is still challenging to generate diverse and accurate scaffold structures around motifs for models either fine-tuned pre-trained multiple sequence alignment-based (MSA-based) structure prediction models or trained from scratch. Here, we introduced Generative Protein Design by Language model (GPDL) for effectively replacing traditional MSA-based pretraining. Using our scalable design strategy, GPDL successfully solved 22 out of 24 benchmark problems and outperformed other methods by generating 33.5% more unique designable clusters than RFdiffusion. This demonstrates that our approach can generate accurate and physically plausible structures across diverse protein design scenarios. GPDL also showed strong robustness in orphan proteins that have low sequence similarity with the training set. Our approach underscores the promise of protein language models in protein design and has the potential to accelerate the discovery of novel functional proteins for a wide range of biological and therapeutic applications.

bioinformatics↗

bioRxiv2023

ClusterV-Web: A User-Friendly Tool for Profiling HIV Quasispecies and Generating Drug Resistance Reports from Nanopore Long-Read Data

SummaryThird-generation long-read sequencing is an increasingly utilized technique for profiling HIV quasispecies and detecting drug resistance mutations due to its ability to cover the entire viral genome in individual reads. Recently, the ClusterV tool has demonstrated accurate detection of HIV quasispecies from Nanopore long-read sequencing data. However, the need for scripting skills and a computational environment may act as a barrier for many potential users. To address this issue, we have introduced ClusterV-Web, a user-friendly web-based application that enables easy configuration and execution of ClusterV, both remotely and locally. Our tool provides interactive tables and data visualizations to aid in the interpretation of results. This development is expected to democratize access to long-read sequencing data analysis, enabling a wider range of researchers and clinicians to efficiently profile HIV quasispecies and detect drug resistance mutations. Availability and implementationClusterV-Web is freely available and open source, with detailed documentation accessible at http://www.bio8.cs.hku.hk/ClusterVW/. The standalone Docker image and source code are also available at https://github.com/HKU-BAL/ClusterV-Web. Contactrbluo@cs.hku.hk, Department of Computer Science, The University of Hong Kong, Hong Kong, China; jhsu@cs.hku.hk, Department of Computer Science, The University of Hong Kong, Hong Kong, China Supplementary informationNone

bioinformatics↗

bioRxiv2023

ZHX2 alleviates vascular remodeling and smooth muscle cell proliferation by transcriptional regulation of GADD45G

ObjectiveThis study explores the role of ZHX2 in vascular remodeling, specifically focusing on its effects on VSMC proliferation, migration, and neointima formation following vascular injury. Methods and Results: Data from both human atherosclerotic samples and a mouse carotid injury model indicated a decrease in ZHX2 levels. In vivo, ZHX2 overexpression reduced neointima formation in mice subjected to carotid artery ligation. In vitro, ZHX2 inhibited the proliferation and migration of primary VSMCs. Conversely, specific knockout of ZHX2 in SMCs in vivo or knockdown of ZHX2 in primary VSMCs had opposite effects. RNA- seq analysis revealed that ZHX2 overexpression significantly affected the expression of cell cycle-related genes. Using Chromatin Immunoprecipitation Sequencing (ChIP-seq) and luciferase reporter assays, we demonstrated that ZHX2 plays a crucial role in the transcriptional regulation of GADD45G, identifying GADD45G as the downstream target responsible for ZHX2-mediated effects. Conclusions: ZHX2 emerges as a key player in pathological vascular remodeling, suppressing VSMC proliferation and migration through its regulatory impact on GADD45G transcription and cell cycle-related gene expression.

molecular biology↗

bioRxiv2023

Oligodendroglial precursors orchestrate immune network instigating early demyelination in experimental autoimmune encephalomyelitis

The immunomodulatory cellular network that triggers early inflammation and demyelination, the key steps in multiple sclerosis (MS) pathogenesis remains poorly characterized. Here, we demonstrate that overactivation of Wnt pathway promotes pathological transformation of oligodendrocyte precursor cells (OPCs) to replicate pathological OPCs in human MS. In mouse experimental autoimmune encephalomyelitis (EAE), pathological OPCs attract CD4+ T-helper 1 (Th1) cells into the spinal cord and brain through CC-chemokine ligand 4 (CCL4), whilst OPCs cooperate with Th1 cells inducing transformation of cytotoxic macrophages that execute early demyelination. Simultaneously, Th1 cells and cytotoxic macrophages upregulate Wnt signaling and CCL4 expression in OPCs, thus exerting positive feedback onto the OPC-immune cascade and establishing a vicious cycle propagating EAE pathogenesis. Breaking this cascade by targeting CCL4 reduces immune cell infiltration, alleviates demyelination, and attenuates EAE severity. Our findings demonstrate a closely coordinated network of OPCs and immune cells therefore providing an alternative insight into MS pathophysiology.

neuroscience↗

bioRxiv2023

Structural Flexibility and Disassembly Kinetics of Single Ferritins using Optical Nanotweezers

Ferritin, a spherical protein shell assembled from 24 subunits, functions as an efficient iron storage and release system through its channels. Understanding how various chemicals affect the structural behaviour of ferritin is crucial for unravelling the origins of iron-related diseases in living organisms including humans. In particular, the influence of chemicals on ferritins dynamics and iron release is barely explored at the single-protein level. Here, by employing optical nanotweezers using double nanohole (DNH) structures, we examined the effect of ascorbic acid (reducing reagent) and pH on ferritins conformational dynamics. The dynamics of ferritin increased as the concentration of ascorbic acid approached saturation. At pH 2.0 ferritin exhibited significant structural fluctuations and eventually underwent a stepwise disassembly into fragments. This work, for the first time, tracked the disassembly pathway and kinetics of single ferritins in solution. We identified four critical fragments during its disassembly pathway, which are 22-mer, 12-mer, tetramer, and dimer subunits. Moreover, we presented the first single-molecule evidence of the cooperative disassembly of ferritin. Interrogating ferritins structural change in response to different chemicals holds importance for understanding their roles in iron metabolism, hence facilitating further development of medical treatments for the associated diseases.

biophysics↗

bioRxiv2023

CD36-Pyruvate Kinase M2 Signaling Promotes Macrophage Phagocytosis Through Mitochondrial Reactive Oxygen Species

Macrophage efferocytosis, the process by which phagocytes engulf and remove apoptotic cells (ACs), plays a critical role in maintaining tissue homeostasis. Efficient efferocytosis prevents secondary necrosis, mitigates chronic inflammation, and impedes atherosclerosis progression. However, the regulatory mechanisms of efferocytosis under atherogenic conditions remain poorly understood. We previously demonstrated that oxidized LDL (oxLDL), an atherogenic lipoprotein, induces mitochondrial reactive oxygen species (mtROS) in macrophages via CD36. In this study, we demonstrate that macrophage mtROS facilitate continual efferocytosis through a positive feedback mechanism. However, oxLDL disrupts continual efferocytosis by dysregulating the internalization of ACs. This disruption is mediated by an overproduction of mtROS. Mechanistically, oxLDL/CD36 signaling promotes the translocation of cytosolic PKM2 to mitochondria, facilitated by the chaperone GRP75. Mitochondrial PKM2 then binds to Complex III of the electron transport chain, inducing mtROS production. This study elucidates a novel regulatory mechanism of efferocytosis in atherosclerosis, providing potential therapeutic targets for intervention. SUMMARYMacrophages clear apoptotic cells through a process called efferocytosis, which involves mitochondrial ROS. However, the atherogenic oxidized LDL overstimulates mitochondrial ROS via the CD36-PKM2 pathway, disrupting continual efferocytosis. This finding elucidates a novel molecular mechanism that explains defects in efferocytosis, driving atherosclerosis progression.

immunology↗

bioRxiv2023

Cellular protein painting for structural and binding sites analysis via lysine reactivity profiling with o-phthalaldehyde

The three-dimensional structure and the molecular interaction of proteins determine their roles in many cellular processes. Chemical protein painting with protein mass spectrometry can identify changes in structural conformations and molecular interactions of proteins including their binding sites. Nevertheless, most current protein painting techniques identified protein targets and binding sites of drugs in vitro using cell lysate or purified protein. Here, we screened 11 membrane-permeable lysine-reactive chemical probes for intracellular covalent labeling of endogenous proteins, which reveals ortho-phthalaldehyde (OPA) as the most reactive probe in intracellular environment. An MS workflow was developed and coupled with a new data analysis strategy termed RAPID (Reactive Amino acid Profiling by Inverse Detection) to enhance detection sensitivity. RAPID-OPA successfully identified structural change induced by allosteric drug TEPP-46 on its target protein PKM2, and was applied to profile conformation change of the proteome occurring in cells during thermal denaturation. Application of RAPID-OPA on cells treated with geldanamycin, selumetinib, and staurosporine successfully revealed their binding sites on target proteins. Thus, RAPID-OPA for cellular protein painting permits the identification of ligand-binding sites and detection of protein structural changes occurring in cells. Significance StatementProtein painting can be used to identify changes in the three-dimensional structure and molecular interaction of proteins that govern many cellular processes but are mostly applied to cell lysate or purified protein. We identified lysine reactive probes for the intracellular labeling of endogenous proteins, and developed an MS procedure with new data analysis strategy termed RAPID-OPA to characterize the intracellular conformation change of the proteome during thermal denaturation, and identified structural change mediated by allosteric regulator TEPP-46 on target protein PKM2. Furthermore, the approach could identify ligand binding sites exemplified by labeling of target proteins in cells treated with geldanamycin, selumetinib and staurosporine. Overall, RAPID-OPA for cellular protein painting enables the detection of protein structural changes happening in cells as well as the identification of ligand-binding sites.

cell biology↗

bioRxiv2023

ClairS: a deep-learning method for long-read somatic small variant calling

Identifying somatic variants in tumor samples is a crucial task, which is often performed using statistical methods and heuristic filters applied to short-read data. However, with the increasing demand for long-read somatic variant calling, existing methods have fallen short. To address this gap, we present ClairS, the first deep-learning-based, long-read somatic small variant caller. ClairS was trained on massive synthetic somatic variants with diverse coverages and variant allele frequencies (VAF), enabling it to accurately detect a wide range of somatic variants from paired tumor and normal samples. We evaluated ClairS using the latest Nanopore Q20+ HCC1395-HCC1395BL dataset. With 50-fold/25-fold tumor/normal, ClairS achieved a 93.01%/86.86% precision/recall rate for Single Nucleotide Variation (SNVs), and 66.54%/66.89% for somatic insertions and deletions (Indels). Applying ClairS to short-read datasets from multiple sources showed comparable or better performance than Strelka2 and Mutect2. Our findings suggest that improved read phasing enabled by long-read sequencing is key to accurate long-read SNV calling, especially for variants with low VAF. Through experiments across various coverage, purity, and contamination settings, we demonstrated that ClairS is a reliable somatic variant caller. ClairS is open-source at https://github.com/HKU-BAL/ClairS.

bioinformatics↗

bioRxiv2023

A Computational Model of Hippocampus: A Unified Theory About Engram and Sharp-Ware Ripples

The hippocampus is key to memory encoding, consolidation, and retrieval. Previous work shows that neurons in the hippocampus fire in sequence to encode spatial information. The same group of cells will replay in memory consolidation, coupled with ripples, spindle, and slow waves. As for episodic memory, engram cells have been proposed to explain the encoding and transformation of episodic memory. Another universe theory about memory is the cognitive map theory. Here I use cognitive map theory as the bridge to overcome the gap between spatial and episodic memory. I believe spatial memory is a highly compressed case of episodic memory. In addition, I propose the hypothesis that engram can trigger sharp-wave ripples. I use a spike neural network-based computational model to verify this hypothesis. In conclusion, I believe engram cells and sharp-wave ripples are two different phenomena under a unified memory system.

neuroscience↗

bioRxiv2023

Disease-associated gut microbiome and metabolome changes in chronic low back pain patients with bone marrow lesions

Chronic low back pain (LBP) is the leading cause of global disability. Vertebral bone marrow lesions (BMLs), one etiological factor for chronic LBP, are MRI signal changes in the vertebral bone marrow that extend from the disc endplate. The adipogenesis of bone marrow mesenchymal stem cells (BM-MSCs) could explain fatty replacement (FR) in normal bone marrow. FR is the most common type of BMLs. Here we show how the gut microbiome and serum metabolome change and how they interact in LBP patients with or without FR. The serum metabolome of chronic LBP patients with FR is characterized by decreased levels of branched-chain amino acids (BCAAs), which correlate with a gut microbiome that has important capability to regulate BCAA degradation pathway. Ruminococcus gnavus, Roseburia hominis and Lachnospiraceae bacterium 8 1 57FAA are identified as the main species driving the association between biosynthesis of BCAAs and BM-MSCs metabolism in LBP with FR individuals. In vitro work demonstrates that BCAAs can induce the adipogenesis of BM-MSCs by activating the SIRT4 pathway. Our findings provide a deep insight into understanding the role of the disturbed gut ecosystem in FR and LBP.

cell biology↗

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

Dendrimeric DNA Coordinate Barcoding Design for Spatial RNA Sequencing

Spatially resolved transcriptomic technologies show promise in revealing complex pathophysiological processes, but developing sensitive, high-resolution, and cost-effective methodology is challenging. Here, we report a dendrimeric DNA coordinate barcoding design for spatial RNA sequencing (Decoder-seq). This technology combined dendrimeric nano-substrates with microfluidic coordinate barcoding to generate high-density spatial DNA arrays with deterministically combinatorial barcodes in a resolution-flexible and cost-effective manner ([~]$0.5/mm2). Decoder-seq achieved high RNA capture efficiency, [~]68.9% that of in situ sequencing, and enhanced the detection of lowly expressed genes by [~]five-fold compared to 10x Visium. Decoder-seq visualized a spatial single-cell atlas of mouse hippocampus at near-cellular resolution (15 m) and revealed dendrite-enriched mRNAs. Application to renal cancers dissected the heterogeneous tumor microenvironment of two subtypes, and identified spatial gradient expressed genes with the potential in predicting tumor prognosis and progression. Decoder-seq is compatible with sensitivity, resolution, and cost, making spatial transcriptomic analysis accessible to wider biomedical applications and researchers.

genomics↗

bioRxiv2023

Boosting variant-calling performance with multi-platform sequencing data using Clair3-MP

BackgroundWith the continuous advances in third-generation sequencing technology and the increasing affordability of next-generation sequencing technology, sequencing data from different sequencing technology platforms is becoming more common. While numerous benchmarking studies have been conducted to compare variant-calling performance across different platforms and approaches, little attention has been paid to the potential of leveraging the strengths of different platforms to optimize overall performance, especially integrating Oxford Nanopore and Illumina sequencing data. ResultsWe investigated the impact of multi-platform data on the performance of variant calling through carefully designed experiments with a deep learning-based variant caller named Clair3-MP (Multi-Platform). Through our research, we not only demonstrated the capability of ONT-Illumina data for improved variant calling, but also identified the optimal scenarios for utilizing ONT-Illumina data. In addition, we revealed that the improvement in variant calling using ONT-Illumina data comes from an improvement in difficult genomic regions, such as the large low-complexity regions and segmental and collapse duplication regions. Moreover, Clair3-MP can incorporate reference genome stratification information to achieve a small but measurable improvement in variant calling. Clair3-MP is accessible as an open-source project at: https://github.com/HKU-BAL/Clair3-MP. ConclusionsThese insights have important implications for researchers and practitioners alike, providing valuable guidance for improving the reliability and efficiency of genomic analysis in diverse applications.

bioinformatics↗

bioRxiv2023

Rotten to the core - a neurofunctional signature of subjective core disgust generalizes to socio-moral contexts

While disgust originates in the hard-wired mammalian distaste response, the conscious experience of disgust in humans strongly depends on subjective appraisal and may even extend to sociomoral contexts. In a series of studies, we combined functional magnetic resonance imaging (fMRI) with machine-learning based predictive modeling to establish a comprehensive neurobiological model of subjective disgust. The developed neurofunctional signature accurately predicted momentary self-reported subjective disgust across discovery (n=78) and pre-registered validation (n=30) cohorts and generalized across core disgust (n=34 and n=26), gustatory distaste (n=30), and sociomoral (unfair offers; n=43) contexts. Disgust experience was encoded in distributed cortical and subcortical systems, and exhibited distinct and shared neural representations with subjective fear or negative affect in interoceptive-emotional awareness and conscious appraisal systems while the signatures most accurately predicted the respective target experience. We provide an accurate fMRI-signature for disgust with a high potential to resolve ongoing evolutionary debates.

neuroscience↗

bioRxiv2023

Evolution of High-Molecular-Mass Hyaluronic Acid is Associated with Subterranean Lifestyle

Hyaluronic acid (HA) is a major component of extracellular matrix (ECM) which plays an important role in development, cellular response to injury and inflammation, cell migration, and cancer. The naked mole-rat (NMR, Heterocephalus glaber) contains abundant high-molecular-mass HA (HMM-HA) in its tissues, which contributes to this species cancer resistance and possibly longevity. Here we report that abundant HMM-HA is found in a wide range of subterranean mammalian species, but not in phylogenetically related aboveground species. These species accumulate abundant HMM-HA by regulating the expression of genes involved in HA degradation and synthesis and contain unique mutations in these genes. The abundant high molecular weight HA may benefit the adaptation to subterranean environment by increasing skin elasticity and protecting from oxidative stress due to hypoxic subterranean environment. HMM-HA may also be coopted to confer cancer resistance and longevity to subterranean mammals. Our work suggests that HMM-HA has evolved with subterranean lifestyle.

evolutionary biology↗

bioRxiv2023

Brain structure-function relationships across the human lifespan based on network eigenmodes

While brain function is considered to be tightly supported by the underlying structure, the connectome-based link estimated by current models is relatively moderate, leaving the structure-function relationship an ongoing challenge in neuroscience. Here, by proposing a novel mapping method based on network eigendecomposition, we present a concise and strong correspondence between structure and function. We show that the explanation of functional connectivity can be significantly improved by incorporating interactions between different structural eigenmodes, highlighting the potential importance of collective, higher-order coupling patterns between structure and function. We also demonstrate the pronounced advantage of the present mapping in capturing individual-specific information, and apply it to assess individual differences of structure-function coupling across the lifespan. We find that structure-function liberality weakens with age, which is driven by the decreases in functional components that are less constrained by anatomy, while the magnitude of structure-aligned components is preserved. Our results contribute to a more refined understanding of structure-function coupling and how it evolves with age.

neuroscience↗

bioRxiv2023

Title: Leveraging Base Pair Mammalian Constraint to Understand Genetic Variation and Human Disease

Although thousands of genomic regions have been associated with heritable human diseases, attempts to elucidate biological mechanisms are impeded by a general inability to discern which genomic positions are functionally important. Evolutionary constraint is a powerful predictor of function that is agnostic to cell type or disease mechanism. Here, single base phyloP scores from the whole genome alignment of 240 placental mammals identified 3.5% of the human genome as significantly constrained, and likely functional. We compared these scores to large-scale genome annotation, genome-wide association studies (GWAS), copy number variation, clinical genetics findings, and cancer data sets. Evolutionarily constrained positions are enriched for variants explaining common disease heritability (more than any other functional annotation). Our results improve variant annotation but also highlight that the regulatory landscape of the human genome still needs to be further explored and linked to disease.

genomics↗