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Hou, W.

Publications and source records attributed to Hou, W..

At least 55 records · Page 3Linked to original sources

Quartet RNA reference materials and ratio-based reference datasets for reliable transcriptomic profiling

As an indispensable tool for transcriptome-wide analysis of differential gene expression, RNA sequencing (RNAseq) has demonstrated great potential in clinical applications. However, the lack of multi-group RNA reference materials of biological relevance and the corresponding reference datasets for assessing the reliability of RNAseq hampers its wide clinical applications wherein the underlying biological differences among study groups are often small. As part of the Quartet Project for quality control and data integration of multiomic profiling, we established four RNA reference materials derived from immortalized B-lymphoblastoid cell lines from four members of a monozygotic twin family. Additionally, we constructed ratio-based transcriptome-wide reference datasets using multi-batch RNAseq datasets, providing "ground truth" for benchmarking. Moreover, Quartet-sample-based quality metrics were developed for assessing reliability of RNAseq technology in terms of intra-batch proficiency and cross-batch reproducibility. The small intrinsic biological differences among the Quartet samples enable sensitive assessment of performance of transcriptomic measurements. The Quartet RNA reference materials combined with the reference datasets can be served as unique resources for assessing data quality and improving reliability of transcriptomic profiling.

genetics↗

Decomposing spatial heterogeneity of cell trajectories with Paella

Spatial transcriptomics provides a unique opportunity to study continuous biological processes in a spatial context. We developed Paella, a computational method to decompose a cell trajectory into multiple spatial sub-trajectories and identify genes with differential temporal patterns across spatial sub-trajectories. Applied to spatial transcriptomics datasets of cancer, Paella identified spatially varying genes associated with tumor progression, providing insights into the spatial heterogeneity of cancer development.

bioinformatics↗

Metabolic control of histone acetylation for precise and timely regulation of minor ZGA in early mammalian embryos

Metabolism feeds into the regulation of epigenetics via metabolic enzymes and metabolites. However, metabolic features, and their impact on epigenetic remodeling during mammalian pre-implantation development, remain poorly understood. In this study, we established the metabolic landscape of mouse pre-implantation embryos from zygote to blastocyst, and quantified some absolute carbohydrate metabolites. We integrated these data with transcriptomic and proteomic data, and discovered the metabolic characteristics of the development process, including the activation of methionine cycle from 8-cell embryo to blastocyst, high glutaminolysis metabolism at blastocyst stage, enhanced TCA cycle activity from the 8-cell embryo stage, and active glycolysis in the blastocyst. We further demonstrated that oxidized nicotinamide adenine dinucleotide (NAD+) synthesis is indispensable for mouse pre-implantation development. Mechanistically, in part, NAD+ is required for the exit of minor zygotic gene activation (ZGA) by cooperating with SIRT1 to remove zygotic H3K27ac. In human, NAD+ supplement can promote the removal of zygotic H3K27ac and benefit pre-implantation development. Our findings demonstrate that precise and timely regulation of minor ZGA is controlled by metabolic dynamics, and enhance our understanding of the metabolism of mammalian early embryos. HighlightsO_LIWe identified the metabolic features of mouse pre-implantation embryo development. C_LIO_LINAD+ synthesis is indispensable for mouse embryo pre-implantation development. C_LIO_LINAD+-mediated erasure of zygotic H3K27ac is required for the exit of minor ZGA. C_LIO_LINAD+ supplement promotes the removal of zygotic H3K27ac and benefits preimplantation development of human embryos. C_LI

developmental biology↗

Palo: Spatially-aware color palette optimization for single-cell and spatial data

SummaryIn the exploratory data analysis of single-cell or spatial genomic data, single cells or spatial spots are often visualized using a two-dimensional plot where cell clusters or spot clusters are marked with different colors. With tens of clusters, current visualization methods often assigns visually similar colors to spatially neighboring clusters, making it hard to identify the distinction between clusters. To address this issue, we developed Palo that optimizes the color palette assignment for single-cell and spatial data in a spatially-aware manner. Palo identifies pairs of clusters that are spatially neighboring to each other and assigns visually distinct colors to those neighboring pairs. We demonstrate that Palo leads to improved visualization in real single-cell and spatial genomic datasets. AvailabilityPalo R package is freely available at https://github.com/Winnie09/Palo. Contactzhicheng.ji@duke.edu

bioinformatics↗

Lineage-mosaic and mutation-patched spike proteins for broad-spectrum COVID-19 vaccine

The widespread SARS-CoV-2 in humans results in the continuous emergence of new variants. Recently emerged Omicron variant with multiple spike mutations sharply increases the risk of breakthrough infection or reinfection, highlighting the urgent need for new vaccines with broad-spectrum antigenic coverage. Using inter-lineage chimera and mutation patch strategies, we engineered a recombinant monomeric spike variant (STFK1628x), which showed high immunogenicity and mutually complementary antigenicity to its prototypic form (STFK). In hamsters, a bivalent vaccine comprised of STFK and STFK1628x elicited high titers of broad-spectrum antibodies to neutralize all 14 circulating SARS-CoV-2 variants, including Omicron; and fully protected vaccinees from intranasal SARS-CoV-2 challenges of either the ancestral strain or immune-evasive Beta variant. Strikingly, the vaccination of hamsters with the bivalent vaccine completely blocked the within-cage virus transmission to unvaccinated sentinels, for either the ancestral SARS-CoV-2 or Beta variant. Thus, our study provides new insights and antigen candidates for developing next-generation COVID-19 vaccines.

microbiology↗

Comprehensive mapping of the alternative polyadenylation site usage and its dynamics at single cell resolution

Alternative polyadenylation (APA) plays an important role in post-transcriptional gene regulation such as transcript stability and translation efficiency. However, our knowledge about APA dynamics at single cell level is largely unexplored. Here we developed single cell polyadenylation sequencing (scPolyA-seq), a strand-specific approach for sequencing 3 end of transcripts, to investigate the landscape of APA at single cell level. By analyzing several cell lines, we found many genes using multiple polyA sites in bulk data are prone to use only one polyA site in each single cell. Interestingly, cell cycle was significantly enriched in genes showing high variation of polyA site usages. We further identified 414 genes showing polyA site usage switch after cell synchronization. Genes showing cell cycle associated polyA site usage switch were grouped into 6 clusters, with cell phase specific functional categories enriched in each cluster. Furthermore, scPolyA-seq could facilitate study of APA in various biological processes.

bioinformatics↗

A statistical framework for differential pseudotime analysis with multiple single-cell RNA-seq samples

Pseudotime analysis with single-cell RNA-sequencing (scRNA-seq) data has been widely used to study dynamic gene regulatory programs along continuous biological processes. While many computational methods have been developed to infer the pseudo-temporal trajectories of cells within a biological sample, methods that compare pseudo-temporal patterns with multiple samples (or replicates) across different experimental conditions are lacking. Lamian is a comprehensive and statistically-rigorous computational framework for differential multi-sample pseudotime analysis. It can be used to identify changes in a biological process associated with sample covariates, such as different biological conditions, and also to detect changes in gene expression, cell density, and topology of a pseudotemporal trajectory. Unlike existing methods that ignore sample variability, Lamian draws statistical inference after accounting for cross-sample variability and hence substantially reduces sample-specific false discoveries that are not generalizable to new samples. Using both simulations and real scRNA-seq data, including an analysis of differential immune response programs between COVID-19 patients with different disease severity levels, we demonstrate the advantages of Lamian in decoding cellular gene expression programs in continuous biological processes.

genomics↗

Mesenchymal stem cell subpopulations and their heterogeneity of response to inductions revealed by single-cell RNA-seq

Mesenchymal stem/stromal cells (MSCs) are promising cell source for regenerative medicine and treatment of autoimmune disorders. Comparing MSCs from different tissues at single cell level is fundamental for optimizing clinical applications. Here we analyzed single cell RNA-seq data of MSCs from 4 tissues, namely umbilical cord, bone marrow, synovial tissue and adipose tissue. We identified 3 major cell subpopulations, namely osteo-MSCs, chondro-MSCs, adipo/myo-MSCs, across all MSC samples. MSCs from umbilical cord exhibited the highest immunosuppression, potentially indicating it is the best immune modulator for autoimmune diseases. The differentiation potentials of MSC subpopulations, which are strongly associated with their subtypes and tissue sources, showed pronounced subpopulation differences. We found MSC subpopulations expanded and differentiated when their subtypes consist with induction directions, while the other subpopulations shrank. We identified the genes and transcription factors underlying each induction at single cell level and subpopulation level, providing better targets for improving induction efficiency.

genetics↗

Cardiac Nmnat/NAD+/SIR2 pathways activation mediates endurance exercise resistance to heart defects induced by a high-fat diet in aging Drosophila

Endurance exercise is an important way to resist and treat a high-fat-diet(HFD)-induced heart defects, but the underlying molecular mechanisms are poorly understood. Here, we used Drosophila to identify whether cardiac Nmnat/NAD+/SIR2 pathways activation could mediate endurance exercise resistance to heart defects. The results showed that endurance exercise activated the cardiac Nmnat/NAD+/SIR2/FOXO pathway and Nmnat/NAD+/SIR2/PGC-1 pathway, including up-regulating cardiac Nmnat, SIR2, FOXO, PGC-1 expression, SOD activity, and NAD+ level, and it prevented HFD-induced or cardiac Nmnat knock-down-induced cardiac lipid accumulation, MDA content and fibrillation increase, and fractional shortening decrease. Cardiac Nmnat overexpression activated heart Nmnat/NAD+/SIR2 pathways and resisted HFD-induced cardiac malfunction, but it could not protect against HFD-induced lifespan reduction and locomotor impairment. Exercise improved lifespan and mobility in cardiac Nmnat knockdown flies. Therefore, current results confirmed that cardiac Nmnat/NAD+/SIR2 pathways were important antagonists of HFD-induced heart defects. The cardiac Nmnat/NAD+/SIR2 pathways activation was the important underlying molecular mechanism of endurance exercise and cardiac Nmnat overexpression against heart defects in Drosophila.

genetics↗

Recombinant chimpanzee adenovirus AdC7 expressing dimeric tandem-repeat RBD of SARS-CoV-2 spike protein protects mice against COVID-19

A safe and effective vaccine is urgently needed to control the unprecedented COVID-19 pandemic. Four adenovirus vectored vaccines expressing spike (S) protein have advanced into phase 3 trials, with three approved for use. Here, we generated several recombinant chimpanzee adenovirus (AdC7) vaccines expressing S, receptor-binding domain (RBD) or dimeric tandem-repeat RBD (RBD-tr2). We found vaccination via either intramuscular or intranasal route was highly immunogenic in mice to elicit both humoral and cellular (Th1-based) immune responses. AdC7-RBD-tr2 showed higher antibody responses compared with both AdC7-S and AdC7-RBD. Intranasal administration of AdC7-RBD-tr2 additionally induced mucosal immunity with neutralizing activity in bronchoalveolar lavage fluid. Either single-dose or two-dose mucosal administration of AdC7-RBD-tr2 protected mice against SARS-CoV-2 challenge, with undetectable subgenomic RNA in lung and relieved lung injury. These results support AdC7-RBD-tr2 as a promising COVID-19 vaccine candidate.

immunology↗

Large-scale single-cell analysis reveals critical immune characteristics of COVID-19 patients

Dysfunctional immune response in the COVID-19 patients is a recurrent theme impacting symptoms and mortality, yet the detailed understanding of pertinent immune cells is not complete. We applied single-cell RNA sequencing to 284 samples from 205 COVID-19 patients and controls to create a comprehensive immune landscape. Lymphopenia and active T and B cell responses were found to coexist and associated with age, sex and their interactions with COVID-19. Diverse epithelial and immune cell types were observed to be virus-positive and showed dramatic transcriptomic changes. Elevation of ANXA1 and S100A9 in virus-positive squamous epithelial cells may enable the initiation of neutrophil and macrophage responses via the ANXA1-FPR1 and S100A8/9-TLR4 axes. Systemic upregulation of S100A8/A9, mainly by megakaryocytes and monocytes in the peripheral blood, may contribute to the cytokine storms frequently observed in severe patients. Our data provide a rich resource for understanding the pathogenesis and designing effective therapeutic strategies for COVID-19. HIGHLIGHTSO_LILarge-scale scRNA-seq analysis depicts the immune landscape of COVID-19 C_LIO_LILymphopenia and active T and B cell responses coexist and are shaped by age and sex C_LIO_LISARS-CoV-2 infects diverse epithelial and immune cells, inducing distinct responses C_LIO_LICytokine storms with systemic S100A8/A9 are associated with COVID-19 severity C_LI

genomics↗

Imaging transmembrane dynamics of biomolecules at live cell plasma membranes using quenchers in extracellular environment

It is a big challenge to measure position changes of biomolecules in the direction normal to the plasma membranes of living cells. We developed a one donor-multiple quenchers F[o]rster resonance energy transfer method by using non-fluorescent quenchers in the extracellular environment. It senses subnanometer position changes of a fluorophore-labeled biomolecule in the plasma membrane. The method was validated by monitoring flip-flops of individual lipid molecules incorporated in plasma membranes. We studies membrane perforation by a host defense peptide from the extracellular side and found that the pore-forming peptide is dynamic, switching among different insertion depths. The method is especially useful in studying interactions of membrane proteins with the inner surfaces of plasma membranes. Our method will find wide applications in systematic analysis of fundamental cellular processes at plasma membranes.

biophysics↗

Rapid host response to an infection with Coronavirus. Study of transcriptional responses with Porcine Epidemic Diarrhea Virus

The transcriptional response in Vero cells (ATCC(R) CCL-81) infected with the coronavirus Porcine Epidemic Diarrhea Virus (PEDV) was measured by RNAseq analysis 4 and 6 hours after infection. Differential expressed genes (DEGs) in PEDV infected cells were compared to DEGs responding in Vero cells infected with Mammalian Orthoreovirus (MRV). Functional analysis of MRV and PEDV DEGs showed that MRV increased the expression level of several cytokines and chemokines (e.g. IL6, CXCL10, IL1A, CXCL8 [alias IL8]) and antiviral genes (e.g. IFI44, IFIT1, MX1, OASL), whereas for PEDV no enhanced expression was observed for these "hallmark" antiviral and immune effector genes. Pathway and Gene Ontology "enrichment analysis" revealed that PEDV infection did not stimulate expression of genes able to activate an acquired immune response, whereas MRV did so within 6h. Instead, PEDV down-regulated the expression of a set of zinc finger proteins with putative antiviral activity and enhanced the expression of the transmembrane serine protease gene TMPRSS13 (alias MSPL) to support its own infection by virus-cell membrane fusion (Shi et al, 2017, Viruses, 9(5):114). PEDV also down-regulated expression of Ectodysplasin A, a cytokine of the TNF-family able to activate the canonical NFKB-pathway responsible for transcription of inflammatory genes like IL1B, TNF, CXCL8 and PTGS2. The only 2 cytokine genes found up-regulated by PEDV were Cardiotrophin-1, an IL6-type cytokine with pleiotropic functions on different tissues and types of cells, and Endothelin 2, a neuroactive peptide with vasoconstrictive properties. Furthermore, by comprehensive datamining in biological and chemical databases and consulting related literature we identified sets of PEDV-response genes with potential to influence i) the metabolism of biogenic amines (e.g. histamine), ii) the formation of cilia and "synaptic clefts" between cells, iii) epithelial mucus production, iv) platelets activation, and v) physiological processes in the body regulated by androgenic hormones (like blood pressure, salt/water balance and energy homeostasis). The information in this study describing a "very early" response of epithelial cells to an infection with a coronavirus may provide pharmacologists, immunological and medical specialists additional insights in the underlying mechanisms of coronavirus associated severe clinical symptoms including those induced by SARS-CoV-2. This may help them to fine-tune therapeutic treatments and apply specific approved drugs to treat COVID-19 patients.

microbiology↗

Virus-free and live-cell visualizing SARS-CoV-2 cell entry for studies of neutralizing antibodies and compound inhibitors

The ongoing COVID-19 pandemic, caused by SARS-CoV-2 infection, has resulted in hundreds of thousands of deaths. Cellular entry of SARS-CoV-2, which is mediated by the viral spike protein and host ACE2 receptor, is an essential target for the development of vaccines, therapeutic antibodies, and drugs. Using a mammalian cell expression system, we generated a recombinant fluorescent protein (Gamillus)-fused SARS-CoV-2 spike trimer (STG) to probe the viral entry process. In ACE2-expressing cells, we found that the STG probe has excellent performance in the live-cell visualization of receptor binding, cellular uptake, and intracellular trafficking of SARS-CoV-2 under virus-free conditions. The new system allows quantitative analyses of the inhibition potentials and detailed influence of COVID-19-convalescent human plasmas, neutralizing antibodies and compounds, providing a versatile tool for high-throughput screening and phenotypic characterization of SARS-CoV-2 entry inhibitors. This approach may also be adapted to develop a viral entry visualization system for other viruses.

microbiology↗

A sweet-tasting sugar drives aversive responses in caterpillars

Exploring botanical biopesticide is one of the eco-friendly approaches for pest control in current crop protection. L-arabinose, a plant-specific and less absorptive pentose, is known for its selective inhibitory effect on the sucrose digestion in mammals. In this study, we investigated the effects of L-arabinose on the feeding preference, the peripheral gustatory perception, the larval development, as well as the activity of intestinal sucrase of an insect pest species, the cotton bollworm Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), in an attempt to explore the antifeedant activities of this pentose. The results showed that L-arabinose deterred the feeding preferences of H. armigera caterpillars for its two host plants and two phagostimulants, the tobacco, the pepper, the sucrose and the fructose. Gustatory receptor neurons (GRNs) sensitive to L-arabinose were not found in the peripheral maxillary sensilla of H. armigera caterpillars, but the sensitivities of GRNs sensitive to sucrose, fructose and tobacco saps were suppressed by the additions of L-arabinose. Exposure of H. armigera caterpillars to dietary L-arabinose resulted in a prolonged larval developmental duration, a suppressed activity of intestinal sucrase and a reduced glucose level in midgut. In vitro, L-arabinose inhibited activities of the intestinal sucrase of H. armigera caterpillars in an uncompetitive manner. Taken together, these findings demonstrate that L-arabinose is a behavioral, gustatory and physiological inhibitor to caterpillars of the extremely generalist pest species H. armigera, suggesting the great potential of L-arabinose to be an effective antifeedant.

animal behavior and cognition↗

A simple method for isolating high-quality RNA from kenaf containing high polysaccharide and polyphenol contents

The isolation of high-quality RNA from kenaf is crucial for genetic and molecular biology studies. However, high levels of polysaccharide and polyphenol compounds in kenaf tissues could irreversibly bind to and coprecipitate with RNA, which complicates RNA extraction. In the present study, we proposed a simplified, time-saving and low-cost extraction method for isolating high quantities of high-quality RNA from several different kenaf tissues. RNA quality was measured for yield and purity, and the proposed protocol yielded high quantities of RNA (10.1-12.9 μg/g·FW). Spectrophotometric analysis showed that A260/280 ratios of RNA samples were in the range of 2.11 to 2.13, and A260/230 ratios were in the range of 2.04-2.24, indicating that the RNA samples were free of polyphenols, polysaccharides, and protein contaminants after isolation. The method of RNA extraction presented here was superior to the conventional CTAB method in terms of RNA isolation efficiency and was more sample-adaptable and cost-effective than commercial kits. Furthermore, to confirm downstream amenability, the high-quality RNA obtained from this method was successfully used for RT-PCR, real-time RT-PCR and Northern blot analysis. We provide an efficient and low-cost method for extracting high quantities of high-quality RNA from plants that are rich in polyphenols and polysaccharides, and this method was also validated for the isolation of high-quality RNA from other plants.View Full Text

genetics↗

A pathway of NADPH diaphorase positivity between central canal and pial surface at anterior fissure in spinal cord: Supra fissure area with hypothesis configuring from dog, rat, monkey and pigeon

The spinal cord is a cylinder structure in the vertebra and thought a simplified with the gray matter and white matter. Rexed lamination for the gray matter and regional sub-division for whiter matter are completely termed to date. Anterior commissure locates between the central canal and the anterior median fissure. However, some experimental data may still confront with new confined anatomical interpretation. By using NADPH diaphorase [N-d] enzyme histology, we found a vertical oriented neuronal pathway between the central canal and the anterior median fissure in the sacral spinal cord of young adult and aged dog. We used a term "supra fissure area" [SFA] to illustrate the region which consisted of the gray commissure and anterior white commissure. The N-d pathway was notably observable in aged animals. The vertical neurites revealed the cerebrospinal fluid [CSF] contacting neurites between the anterior median fissure and the central canal. We further examined the monkey, rat and pigeon in the region for better understanding of the structure and potential function. The neurodegeneration of N-d dystrophy was detected in the [SFA] in the thoracic spinal cord of the aged monkey. N-d positive fibers were detected in anterior fissure of the rat spinal cord. N-d fibrous structures were also detected in the pigeon spinal cord. These results suggested a new pathway of CSF contacting neurons and the neuronal communications about the central canal.

neuroscience↗

Robust neutralization assay based on SARS-CoV-2 S-bearing vesicular stomatitis virus (VSV) pseudovirus and ACE2-overexpressed BHK21 cells

The global pandemic of Coronavirus disease 2019 (COVID-19) is a disaster for human society. A convenient and reliable in vitro neutralization assay is very important for the development of neutralizing antibodies, vaccines and other inhibitors. In this study, G protein-deficient vesicular stomatitis virus (VSVdG) bearing full-length and truncated spike (S) protein of SARS-CoV-2 were evaluated. The virus packaging efficiency of VSV-SARS-CoV-2-Sdel18 (S with C-terminal 18 amino acid truncation) is much higher than VSV-SARS-CoV-2-S. A neutralization assay for antibody screening and serum neutralizing titer quantification was established based on VSV-SARS-CoV-2-Sdel18 pseudovirus and human angiotensin-converting enzyme 2 (ACE2) overexpressed BHK21 cell (BHK21-hACE2). The experimental results can be obtained by automatically counting EGFP positive cell number at 12 hours after infection, making the assay convenient and high-throughput. The serum neutralizing titer of COVID-19 convalescent patients measured by VSV-SARS-CoV-2-Sdel18 pseudovirus assay has a good correlation with live SARS-CoV-2 assay. Seven neutralizing monoclonal antibodies targeting receptor binding domain (RBD) of SARS-CoV-2-S were obtained. This efficient and reliable pseudovirus assay model could facilitate the development of new drugs and vaccines.

microbiology↗