Biology subjects

Zheng, L.

Publications and source records attributed to Zheng, L..

At least 145 records · Page 8Linked to original sources

bioRxiv2023

RNA landscapes of brain tissue and brain tissue-derived extracellular vesicles in simian immunodeficiency virus (SIV) infection and SIV-related central nervous system pathology

IntroductionAntiretroviral treatment regimens can effectively control HIV replication and some aspects of disease progression. However, molecular events in end-organ diseases such as central nervous system (CNS) disease are not yet fully understood, and routine eradication of latent reservoirs is not yet in reach. Brain tissue-derived extracellular vesicles (bdEVs) act locally in the source tissue and may indicate molecular mechanisms in HIV CNS pathology. Regulatory RNAs from EVs have emerged as important participants in HIV disease pathogenesis. Using brain tissue and bdEVs from the simian immunodeficiency virus (SIV) model of HIV disease, we profiled messenger RNAs (mRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), seeking to identify possible networks of RNA interaction in SIV infection and neuroinflammation. MethodsPostmortem occipital cortex tissue were collected from pigtailed macaques: uninfected controls and SIV-infected subjects (acute phase and chronic phase with or without CNS pathology). bdEVs were separated and characterized in accordance with international consensus standards. RNAs from bdEVs and source tissue were used for sequencing and qPCR to detect mRNA, miRNA, and circRNA levels ResultsMultiple dysregulated bdEV RNAs, including mRNAs, miRNAs, and circRNAs, were identified in acute infection and chronic infection with pathology. Most dysregulated mRNAs in bdEVs reflected dysregulation in their source tissues. These mRNAs are disproportionately involved in inflammation and immune responses, especially interferon pathways. For miRNAs, qPCR assays confirmed differential abundance of miR-19a-3p, let-7a-5p, and miR-29a-3p (acute SIV infection), and miR- 146a-5p and miR-449a-5p (chronic with pathology) in bdEVs. In addition, target prediction suggested that several circRNAs that were differentially abundant in source tissue might be responsible for specific differences in small RNA levels in bdEVs during SIV infection. ConclusionsRNA profiling of bdEVs and source tissues reveals potential regulatory networks in SIV infection and SIV-related CNS pathology.

neuroscience↗

bioRxiv2023

Frizzled-9 activates YAP to rescue simulated microgravity induced osteoblasts dysfunction.

Long-term space flight will lead to bone loss and osteoblasts dysfunction. The underlying mechanism is still far to reveal. Frizzled-9 (Fzd9) is a Wnt receptor which is essential to osteoblasts differentiation and bone formation. Here we investigate whether Fzd9 plays a role in simulated microgravity (SMG) induced osteoblasts dysfunction. After 1-3 days of SMG, the osteogenic markers were decreased which accompanied the decline of Fzd9 expression. Fzd9 also decreased in the femur of the rats after 3 weeks of hindlimb unloading. Overexpression of Fzd9 will counteract SMG-induced osteoblasts dysfunction. However, Fzd9 overexpression did not affect SMG induced pGSK3{beta} and {beta}-catenin expression or sublocalization. Overexpression of Fzd9 regulates the phosphorylation of Akt and ERK, as well as induces F-actin polymerization to form the actin cap, presses the nuclei, and increases the nuclear pore size, which promotes nuclear translocation of YAP. Our study provides mechanistic insights into the role of Fzd9 triggers actin polymerization and activates mechano-transducer YAP to rescue SMG-mediated osteoblasts dysfunction and indicates Fzd9 as a potential target to restore osteoblast function in bone diseases and space flight.

cell biology↗

bioRxiv2023

HCC-1 accelerates atherosclerosis by inducing endothelial cells and macrophages pyroptosis and serves as an early diagnostic biomarker

BACKGROUNDHCC-1 (Hemofiltrate CC chemokine-1), a CC-type chemokine, exerts function to change intracellular calcium concentration, induce leukocyte and manipulate enzyme release especially in monocytes. It has been reported that HCC-1 could predict the persistent acute kidney injury (AKI) or suppress hepatocellular carcinoma (HCC) by modulating cell cycle and promoting apoptosis, but the effect of HCC-1 on atherosclerosis is poorly understood. Here, we aimed to clarify the function and mechanism of HCC-1 in atherosclerosis and whether it could serve as a novel biomarker for the diagnosis of atherosclerosis. METHODSHCC-1 expression in serum, atherosclerotic plaques and normal arterial tissue from patients with atherosclerosis and control group was assessed by enzyme-linked immunosorbent assay, immunohistochemistry and con-focal microscope. The atherosclerotic model of HCC-1 overexpressing mice and control mice were generated by infection of AAV9-HCC-1 on an ApoE-/- background. Cell adhesion, polarization and pyroptosis were evaluated in vitro. The relationship between HCC-1 concentration in serum and atherosclerosis was analyzed in patients with atherosclerosis. RESULTSHCC-1 expression increased in patients with atherosclerosis both in serum and atherosclerotic plaque. HCC-1 overexpression mice had an enhancement in macrophage accumulation in plaque, higher levels of inflammatory factors, increased pyroptotic rate in ECs and Macrophages in plaque and decreased atherosclerotic plaque stability. In vitro, HCC-1 promoted monocytes to adhere to endothelial cells and M1 polarization, induced inflammation and pyroptosis both in ECs and Macrophages. CONCLUSIONSHCC-1 expression markedly increased in patients with atherosclerosis and HCC-1 overexpression accelerated atherosclerotic burden via an enhancement in monocytes recruitment, M1 polarization and pyroptosis both in ECs and Macrophages. Our findings suggested that HCC-1 may serve as an early biomarker for the diagnosis of atherosclerosis, with the capacity to reflect the degree of stenosis. GRAPHIC ABSTRACTA graphic abstract is available for this article.

cell biology↗

bioRxiv2023

An Antibody-Based Molecular Switch for Continuous Biosensing

We present a generalizable approach for designing biosensors that can continuously detect specific biomarkers in real time and without sample preparation. This is achieved by converting existing antibodies into target-responsive "antibody-switches" that enable continuous optical biosensing. To engineer these switches, antibodies are linked to a molecular competitor through a DNA scaffold, such that competitive target binding induces scaffold switching and fluorescent signaling of changing target concentrations. As a demonstration, we designed antibody-switches that achieve rapid, sample-preparation-free sensing of digoxigenin and cortisol in undiluted plasma. We showed that, by substituting the molecular competitor, we can further modulate the sensitivity of our cortisol switch to achieve detection at concentrations spanning 3.3 nM to 3.3 mM. Finally, we integrated this switch with a fiber-optic sensor to achieve hours-long continuous sensing of cortisol in buffer with <5-minute time resolution. We believe this modular sensor design can enable continuous biosensor development for many biomarkers.

bioengineering↗

bioRxiv2023

Retrieved Sequence Augmentation for Protein Representation Learning

The advancement of protein representation learning has been significantly influenced by the remarkable progress in language models. Accordingly, protein language models perform inference from individual sequences, thereby limiting their capacity to incorporate evolutionary knowledge present in sequence variations. Existing solutions, which rely on Multiple Sequence Alignments (MSA), suffer from substantial computational overhead and suboptimal generalization performance for de novo proteins. In light of these problems, we introduce a novel paradigm called Retrieved Sequence Augmentation (RSA) that enhances protein representation learning without necessitating additional alignment or preprocessing. RSA associates query protein sequences with a collection of structurally or functionally similar sequences in the database and integrates them for subsequent predictions. We demonstrate that protein language models benefit from retrieval enhancement in both structural and property prediction tasks, achieving a 5% improvement over MSA Transformer on average while being 373 times faster. Furthermore, our model exhibits superior transferability to new protein domains and outperforms MSA Transformer in de novo protein prediction. This study fills a much-encountered gap in protein prediction and brings us a step closer to demystifying the domain knowledge needed to understand protein sequences. Code is available at https://github.com/HKUNLP/RSA.

bioinformatics↗

bioRxiv2023

Three-dimensional genomic mapping of human pancreatic tissue reveals striking multifocality and genetic heterogeneity in precancerous lesions

Pancreatic intraepithelial neoplasia (PanIN) is a precursor to pancreatic cancer and represents a critical opportunity for cancer interception. However, the number, size, shape, and connectivity of PanINs in human pancreatic tissue samples are largely unknown. In this study, we quantitatively assessed human PanINs using CODA, a novel machine-learning pipeline for 3D image analysis that generates quantifiable models of large pieces of human pancreas with single-cell resolution. Using a cohort of 38 large slabs of grossly normal human pancreas from surgical resection specimens, we identified striking multifocality of PanINs, with a mean burden of 13 spatially separate PanINs per cm3 of sampled tissue. Extrapolating this burden to the entire pancreas suggested a median of approximately 1000 PanINs in an entire pancreas. In order to better understand the clonal relationships within and between PanINs, we developed a pipeline for CODA-guided multi-region genomic analysis of PanINs, including targeted and whole exome sequencing. Multi-region assessment of 37 PanINs from eight additional human pancreatic tissue slabs revealed that almost all PanINs contained hotspot mutations in the oncogene KRAS, but no gene other than KRAS was altered in more than 20% of the analyzed PanINs. PanINs contained a mean of 13 somatic mutations per region when analyzed by whole exome sequencing. The majority of analyzed PanINs originated from independent clonal events, with distinct somatic mutation profiles between PanINs in the same tissue slab. A subset of the analyzed PanINs contained multiple KRAS mutations, suggesting a polyclonal origin even in PanINs that are contiguous by rigorous 3D assessment. This study leverages a novel 3D genomic mapping approach to describe, for the first time, the spatial and genetic multifocality of human PanINs, providing important insights into the initiation and progression of pancreatic neoplasia.

cancer biology↗

bioRxiv2023

Variational graph encoders: a surprisingly effective generalist algorithm for holistic computer-aided drug design

1.While there has been significant progress in molecular property prediction in computer-aided drug design, there is a critical need to have fast and accurate models. Many of the currently available methods are mostly specialists in predicting specific properties, leading to the use of many models side-by-side that lead to impossibly high computational overheads for the common researcher. Henceforth, the authors propose a single, generalist unified model exploiting graph convolutional variational encoders that can simultaneously predict multiple properties such as absorption, distribution, metabolism, excretion and toxicity (ADMET), target-specific docking score prediction and drug-drug interactions. Considerably, the use of this method allows for state-of-the-art virtual screening with an acceleration advantage of up to two orders of magnitude. The minimisation of a graph variational encoders latent space also allows for accelerated development of specific drugs for targets with Pareto optimality principles considered, and has the added advantage of explainability.

bioinformatics↗

bioRxiv2022

Gap-free nuclear and mitochondrial genomes of Ustilaginoidea virens strain JS60-2, a fungal pathogen causing rice false smut

Rice false smut (RFS), caused by Ustilaginoidea virens, has become a major disease in recent years, and mycotoxins produced by U. virens often threaten food safety. To study fungal pathogenesis and identify potential targets for developing new fungicides, gap-free nuclear and complete mitochondrial genomes of U. virens JS60-2 were sequenced and assembled. Using the second and third generation sequencing data, we assembled a 38.02-Mb genome that consists of seven contigs with the contig N50 being 6.32-Mb. In total, 8,486 protein-coding genes were annotated in the genome, including 21 secondary metabolism gene clusters. We also assembled the complete mitochondrial genome, which is 102,498 bp, with 28% GC content. The JS60-2 genomes assembled in this study will facilitate research on U. virens and contribute to RFS control.

genomics↗

bioRxiv2022

Structure of human phagocyte NADPH oxidase in the resting state

Phagocyte oxidase plays an essential role in the first line of host defense against pathogens. It oxidizes intracellular NADPH to reduce extracellular oxygen to produce superoxide anions for pathogen killing. The resting phagocyte oxidase is a heterodimeric complex formed by two transmembrane proteins NOX2 and p22. Despite the functional importance of this complex, its structure remains elusive. Here we reported the cryo-EM structure of the human NOX2-p22 complex in nanodisc in the resting state. The structure shows that p22 is formed by four transmembrane helices and interacts with NOX2 through its M1 and M4 helices. Hydrophobic residues on M3, M4, and M5 of NOX2 contribute to the complex formation. Structural analysis suggests that the cytosolic factors activate the NOX2-p22 complex by stabilizing the dehydrogenase domain (DH) in a productive docked conformation which is efficient for electron transfer between DH and the transmembrane domain.

biochemistry↗

bioRxiv2022

DEED: A Dataset for Dream-related Emotion Research

Emotion is closely related to human cognition and behaviour. In recent years, scholars have conducted extensive research on emotion in waking state based on electroencephalography (EEG) and achieved certain results. However, Emotional activity continues after sleep, with a concentrated response of sleep emotions in dreams. Sleep emotions are concentrated in dreams, which can better reflect a series of real physical and psychological states of the human body. Currently, there is no publicly available dataset for the assessment of dream mood. Therefore, we present a physiological dataset Dream Emotion Evaluation Dataset (DEED) for the assessment of dream mood, which recorded EEG signals from 38 participants over 89 whole sleep nights and 533 dream segments(after exclusion of unqualified nights, those dream segments are extracted from 82 whole sleep nights). We studied the correlations between the subjective ratings and the EEG signals and brain network patterns for dream emotions. In addition, the relationship between the asymmetry of left and right brain bands and positive and negative dream emotions was studied. The machine learning algorithm was also used to classify different emotional EEG, which confirmed the validity of the dataset. In the meantime, we encourage other researchers to explore the underlying neural mechanisms involved in sleep.

neuroscience↗

bioRxiv2022

Longitudinal characterization of circulating extracellular vesicles and small RNA during simian immunodeficiency virus infection and antiretroviral therapy

ObjectivesLatent infection by human immunodeficiency virus (HIV) hinders viral eradication despite effective antiretroviral treatment (ART), Amongst proposed contributors to viral latency are cellular small RNAs that have also been proposed to shuttle between cells in extracellular vesicles (EVs). Thus, we profiled EV small RNAs during different infection phases to understand the potential relationship between these EV-associated small RNAs and viral infection. DesignA well characterized simian immunodeficiency virus (SIV)/macaque model of HIV was used to profile EV-enriched blood plasma fractions harvested during pre-infection, acute infection, latent infection/ART treatment, and rebound after ART interruption. MethodsMeasurement of EV concentration, size distribution, and morphology was complemented with qPCR array for small RNA expression, followed by individual qPCR validations. Iodixanol density gradients were used to separate EV subtypes and virions. ResultsPlasma EV particle counts correlated with viral load and peaked during acute infection. However, SIV gag RNA detection showed that virions did not fully explain this peak. EV microRNAs miR-181a, miR-342-3p, and miR-29a decreased with SIV infection and remained downregulated in latency. Interestingly, small nuclear RNA U6 had a tight association with viral load peak. ConclusionsThis study is the first to monitor how EV concentration and EV small RNA expression change dynamically in acute viral infection, latency, and rebound in a carefully controlled animal model. These changes may also reveal regulatory roles in retroviral infection and latency.

microbiology↗

bioRxiv2022

Allosteric Regulation of Aptamer Affinity through Mechano-Chemical Coupling

The capacity to precisely modulate aptamer affinity is important for a wide variety of applications. However, most such engineering strategies entail laborious trial-and-error testing or require prior knowledge of an aptamers structure and ligand-binding domain. We describe here a simple and generalizable strategy for allosteric modulation of aptamer affinity by employing a double-stranded molecular clamp that destabilizes aptamer secondary structure through mechanical tension. We demonstrate the effectiveness of the approach with a thrombin-binding aptamer and show that we can alter its affinity by as much as 65-fold. We also show that this modulation can be rendered reversible by introducing a restriction enzyme cleavage site into the molecular clamp domain and describe a design strategy for achieving even more finely-tuned affinity modulation. This strategy requires no prior knowledge of the aptamers structure and binding mechanism and should thus be generalizable across aptamers.

biochemistry↗

bioRxiv2022

Inflammatory Signaling and Fibroblast-Cancer Cell Interactions Transfer from a Harmonized Human Single-cell RNA Sequencing Atlas of Pancreatic Ductal Adenocarcinoma to Organoid Co-Culture

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy characterized by a heterogeneous tumor microenvironment (TME) that is enriched with cancer associated fibroblasts (CAFs)1. Cell-cell interactions involving these CAFs promote an immunosuppressive phenotype with altered inflammatory gene expression. While single-cell transcriptomics provides a tool to dissect the complex intercellular pathways that regulate cancer-associated inflammation in human tumors, complementary experimental systems for mechanistic validation remain limited. This study integrated single-cell data from human tumors and novel organoid co-cultures to study the PDAC TME. We derived a comprehensive atlas of PDAC gene expression from six published human single-cell RNA sequencing (scRNA-seq) datasets2-7 to characterize intercellular signaling pathways between epithelial tumor cells and CAFs that regulate the inflammatory TME. Analysis of the epithelial cell compartment identified global gene expression pathways that modulate inflammatory signaling and are correlated with CAF composition. We then generated patient-derived organoid-CAF co-cultures to serve as a biological model of the cellular interactions learned from human tissue in the atlas. Transfer learning analysis to additional scRNA-seq data of this co-culture system and mechanistic experiments confirmed the epithelial response to fibroblast signaling. This bidirectional approach of complementary computational and in vitro applications provides a framework for future studies identifying important mechanisms of intercellular interactions in PDAC.

cancer biology↗

bioRxiv2022

Structural and mechanistic insights into the DNA glycosylase AAG-mediated base excision in nucleosome

DNA glycosylase engaging with damaged base marks the initiation of base excision repair. Nucleosome-based packaging of eukaryotic genome obstructs DNA accessibility, and how DNA glycosylases locate the substrate site on nucleosomes is currently unclear. Here, we report cryo-electron microscopy structures of nucleosomes bearing a deoxyinosine (DI) in various geometric positions and structures of them in complex with DNA glycosylase AAG. The apo nucleosome structures show that the presence of a deoxyinosine alone perturbs nucleosomal DNA globally, leading to a general weakening of the interface between DNA and the histone core and a greater flexibility to the exit/entry of the nucleosomal DNA. AAG makes use of this nucleosomal plasticity and imposes further local deformation of the DNA through the formation of the stable enzyme-substrate complex. Mechanistically, local distortion augment, translation/rotational register shift and partial opening of the nucleosome are employed by AAG to cope with substrate sites in fully exposed, occluded and complete buried positions, respectively. Our findings reveal the molecular basis for the DI-induced modification on the structural dynamics of the nucleosome and elucidate how DNA glycosylase AAG accesses damaged sites on the nucleosome with different solution accessibility.

molecular biology↗

bioRxiv2022

Transcriptome analysis of human preimplantation embryo reveals expressed waves associated with blastulation failure based on embryonic grade and age

In the in vitro fertilization and embryo transfer (IVF-ET) treatments, blastocyst culture is the method of choice for the generation of the embryos. Blastocysts can present different growth, quality, availability, and morphological characteristics that can be used to evaluate them. Although extreme blastocyst formation failures have been associated with the alteration of a single gene, the molecular factors responsible for arrested embryos remain unknown. RNA-sequencing (RNA-seq) is a promising tool for facilitating transcriptomic studies in early human embryos, thus allowing the investigation of gene expression discrepancies associated with different morphological criteria. Herein, we performed transcriptome analyses of the different stages of arrested human embryos. We identified candidate genes and related cell signaling pathways potentially associated with either arrested or developed embryos. Specifically, the three genes (MOV10L1, DDX4, and FKBP6) related to both DNA methylation and piRNA metabolic pathway might be involved in embryo development. Additionally, the transcriptome of arrested early blastocysts was significantly different from developed late blastocysts. Although the gene expression profiles identified were not significantly different between low- and high-quality late blastocysts, a significant difference in the profiles of day 5 and day 6 available late blastocysts was observed, which may be related to the clinical pregnancy rate associated with IVF-ET. Furthermore, we show that some chimeric RNAs may be functional in blastocyst development. Our findings uncovered new molecular markers that can be used for embryonic development detection, which might act as a tool for blastocyst selection for subsequent transfer.

genomics↗

bioRxiv2022

Uncovering the spatial landscape of molecular interactions within the tumor microenvironment through latent spaces

Recent advances in spatial transcriptomics (ST) enable gene expression measurements from a tissue sample while retaining its spatial context. This technology enables unprecedented in situ resolution of the regulatory pathways that underlie the heterogeneity in the tumor and its microenvironment (TME). The direct characterization of cellular co-localization with spatial technologies facilities quantification of the molecular changes resulting from direct cell-cell interaction, as occurs in tumor-immune interactions. We present SpaceMarkers, a novel bioinformatics algorithm to infer molecular changes from cell-cell interaction from latent space analysis of ST data. We apply this approach to infer molecular changes from tumor-immune interactions in Visium spatial transcriptomics data of metastasis, invasive and precursor lesions, and immunotherapy treatment. Further transfer learning in matched scRNA-seq data enabled further quantification of the specific cell types in which SpaceMarkers are enriched. Altogether, SpaceMarkers can identify the location and context-specific molecular interactions within the TME from ST data.

bioinformatics↗

bioRxiv2022

A small DNA virus initiates replication with no more than three genome copies per cell

Cellular organisms purge lethal mutations as they occur (in haploids), or as soon as they become homozygous (in sexually reproducing diploids), thus making the mutation-carrying genomes the sole victims of lethality. How lethal mutations in viruses are purged remains an unresolved question because numerous viral genomes could potentially replicate in the same cell, sharing their encoded proteins, hence shielding lethal mutations from selection. Previous investigations by us and others suggest that viruses with plus strand (+) RNA genomes may compel such selection by bottlenecking the replicating genome copies in each cell to low single digits. However, it is unclear if similar bottlenecks also occur in cells invaded by DNA viruses. Here we investigated whether tomato yellow leaf curl virus (TYLCV), a small virus with a single-stranded DNA genome, underwent population bottlenecking in cells of its host plants. We engineered the TYLCV genome to produce two replicons that express green fluorescent protein and mCherry, respectively, in a replication-dependent manner. We found that less than 65% of cells penetrated by both replicons replicated both, whereas at least 35% of cells replicated either of them alone, illustrating an intracellular population bottleneck size of no more than three. Furthermore, sequential inoculations unveiled strong mutual exclusions of these two replicons in most cells. Collectively our data demonstrated for the first time that DNA viruses like TYLCV are subject to stringent intracellular population bottlenecks, suggesting that such population bottlenecks may be a virus-encoded, evolutionarily conserved trait that assures timely elimination of lethal mutations. Significance statementAn important unresolved issue in virus life cycles is how natural selection acts on individual virus copies in the same cells. Unlike cellular organisms in which genome copies with lethal or advantageous mutations usually share their hosts with no more than one homologous genome copy, viruses could potentially reproduce with numerous sister genomes per cell, permitting sharing of protein products, thereby greatly diminishing phenotypic impacts of otherwise eventful mutations. Previous investigations suggest that (+) RNA viruses solve this problem by bottlenecking the number of replicating genome copies to low single digits. The current study reveals strikingly similar intracellular population bottlenecks for a DNA virus. Further mechanistic interrogations could avail the virus-encoded bottleneck-enforcing apparatus as targets for antiviral therapy and prevention.

microbiology↗

bioRxiv2022

Lipid nanoparticle topology regulates endosomal escape and delivery of RNA to the cytoplasm

RNA therapeutics have the potential to resolve a myriad of diseases caused by gene deficiency. Lipid nanoparticles (LNPs) are one of the most successful RNA delivery systems. However, expanding their application hinges on the discovery of next generation LNPs with high potency, cyto-specific targeting, and low side effects. Overcoming the difficulty of releasing cargo from endocytosed LNPs remains a significant hurdle. The endosomal escape of viral and non-viral nanoparticles relies on the topological transformation of membrane fusion pore formation followed by RNA translocation into the cytosol. In this study we show that LNP-RNA nanostructure modulates the energetic cost of LNP fusion with a target membrane. The inclusion of a new class of structurally-active lipids leads to superior LNP endosomal fusion, fast evasion of endosomal entrapment, and efficacious RNA delivery. Specifically, bicontinuous cubic RNA-LNPs, cuboplexes, have significantly higher endosomal escape rates and deliver more RNA compared to regular lamellar LNPs.

bioengineering↗