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Xiong, L.

Publications and source records attributed to Xiong, L..

At least 37 records · Page 2Linked to original sources

Deep learning modeling of ribosome profiling reveals regulatory underpinnings of translatome and interprets disease variants

Gene expression involves transcription and translation. Despite large datasets and increasingly powerful methods devoted to calculating genetic variants effects on transcription, discrepancy between mRNA and protein levels hinders the systematic interpretation of the regulatory effects of disease-associated variants. Accurate models of the sequence determinants of translation are needed to close this gap and to interpret disease-associated variants that act on translation. Here, we present Translatomer, a multimodal transformer framework that predicts cell-type-specific translation from mRNA expression and gene sequence. We train Translatomer on 33 tissues and cell lines, and show that the inclusion of sequence substantially improves the prediction of ribosome profiling signal, indicating that Translatomer captures sequence-dependent translational regulatory information. Translatomer achieves accuracies of 0.72 to 0.80 for de novo prediction of cell-type-specific ribosome profiling. We develop an in silico mutagenesis tool to estimate mutational effects on translation and demonstrate that variants associated with translation regulation are evolutionarily constrained, both within the human population and across species. Notably, we identify cell-type-specific translational regulatory mechanisms independent of eQTLs for 3,041 non-coding and synonymous variants associated with complex diseases, including Alzheimers disease, schizophrenia, and congenital heart disease. Translatomer accurately models the genetic underpinnings of translation, bridging the gap between mRNA and protein levels, and providing valuable mechanistic insights toward mapping "missing regulation" in disease genetics.

genomics↗

TLR2 Regulates Hair Follicle Cycle and Regeneration via BMP Signaling.

The etiology of hair loss remains enigmatic, and current remedies remain inadequate. Transcriptome analysis of aging hair follicles uncovered changes in immune pathways, including Toll-like receptors (TLRs). Our findings demonstrate that the maintenance of hair follicle homeostasis and the regeneration capacity after damage depends on TLR2 in hair follicle stem cells (HFSCs). In healthy hair follicles, TLR2 is expressed in a cycle-dependent manner and governs HFSCs activation by countering inhibitory BMP signaling. Hair follicles in aging and obesity exhibit a decrease in both TLR2 and its endogenous ligand carboxyethylpyrrole (CEP), a metabolite of polyunsaturated fatty acids. Administration of CEP stimulates hair regeneration through a TLR2-dependent mechanism. These results establish a novel connection between TLR2-mediated innate immunity and HFSC activation, which is pivotal to hair follicle health and the prevention of hair loss and provide new avenues for therapeutic intervention. SummaryHair follicle stem cells TLR2 is required for hair homeostasis and regeneration. While TLR2 stimulation by endogenous ligand promotes hair growth, reduction in TLR2 and its ligand in aging and obesity may diminish hair growth.

immunology↗

Direct androgen receptor regulation of sexually dimorphic gene expression in the mammalian kidney

Mammalian organs exhibit distinct physiology, disease susceptibility and injury responses between the sexes. In the mouse kidney, sexually dimorphic gene activity maps predominantly to proximal tubule (PT) segments. Bulk RNA-seq data demonstrated sex differences were established from 4 and 8 weeks after birth under gonadal control. Hormone injection studies and genetic removal of androgen and estrogen receptors demonstrated androgen receptor (AR) mediated regulation of gene activity in PT cells as the regulatory mechanism. Interestingly, caloric restriction feminizes the male kidney. Single-nuclear multiomic analysis identified putative cis-regulatory regions and cooperating factors mediating PT responses to AR activity in the mouse kidney. In the human kidney, a limited set of genes showed conserved sex-linked regulation while analysis of the mouse liver underscored organ-specific differences in the regulation of sexually dimorphic gene expression. These findings raise interesting questions on the evolution, physiological significance, and disease and metabolic linkage, of sexually dimorphic gene activity.

developmental biology↗

Gene regulatory network inference with popInfer reveals dynamic regulation of hematopoietic stem cell quiescence upon diet restriction and aging

Inference of gene regulatory networks (GRNs) can reveal cell state transitions from single-cell genomics data. However, obstacles to temporal inference from snapshot data are difficult to overcome. Single-nuclei multiomics data offer means to bridge this gap and derive temporal information from snapshot data using joint measurements of gene expression and chromatin accessibility in the same single cells. We developed popInfer to infer networks that characterize lineage-specific dynamic cell state transitions from joint gene expression and chromatin accessibility data. Benchmarking against alternative methods for GRN inference, we showed that popInfer achieves higher accuracy in the GRNs inferred. popInfer was applied to study single-cell multiomics data characterizing hematopoietic stem cells (HSCs) and the transition from HSC to a multipotent progenitor cell state during murine hematopoiesis across age and dietary conditions. From networks predicted by popInfer, we discovered gene interactions controlling entry to/exit from HSC quiescence that are perturbed in response to diet or aging.

systems biology↗

Real-Time Quantification of Cell Mechanics and Functions by Double Resonator Piezoelectric Cytometry -Theory and Study of Cellular Adhesion of HUVECs

Cell mechanics is closely associated with cellular structure and function. However, the inability to measure both cellular force and viscoelasticity of statistically significant number of cells noninvasively remains a challenge for quantitative characterizations of various cellular functions and practical applications. Here a double resonator piezoelectric cytometry (DRPC), using AT and BT cut quartz crystals of the same frequency and surface morphology is developed to simultaneously quantify the cells-generated forces ({Delta}S) and viscoelastic moduli (G', G'') of a population of isolated single cells or cells with different degrees of cell-cell interactions in a non-invasive and real time manner. DRPC captures the dynamic mechanical parameters {Delta}S and G', G'' during the adhesions of human umbilical vein endothelial cells (HUVECs) under different ligand densities of adhesion molecules fibronectin or Arg-Gly-Asp (RGD) modified on the gold surfaces of 9 MHz AT and BT cut quartz crystals, and different seeding densities of HUVECs. It is found that both the ligand density and cell seeding density affect the magnitudes of {Delta}S and G', G'' and their correlations are revealed for the first time by DRPC. The validity of DRPC is further verified by mechanical changes of the cells in response to treatments with cytoskeleton regulators.

biophysics↗

Correlation analysis between drug resistance and virulence genes of carbapenem-resistant Acinetobacter baumannii In Western Guilin

BackgoundIn order to detect the resistance of Acinetobacter baumannii to {beta}-lactam antibiotics in western Guilin, analyze the reasons for its resistance, and provide laboratory basis for clinical treatment; method for the {beta}-lactamase gene of Acinetobacter baumannii, and to explore the relationship between the presence of the {beta}-lactamase gene of Acinetobacter baumannii and multidrug resistance. MethodsFrom November 2020 to June 2022, 78 non-repeated Acinetobacter baumannii strains from the Second Affiliated Hospital of Guilin Medical University were collected, and their resistance to carbapenem antibiotics was analyzed. PCR was used to detect resistance-related genes (blaOXA-23, blaOXA-51, blaOXA-58, blaOXA-24, blaIMP and blaSIM) and virulence genes (cusE, abaI and bfmS). To analyze the relationship between drug resistance and virulence genes of Acinetobacter baumannii. ResultsMost of the 165 non-enterobacteriaceae bacteria we collected from the hospital were Acinetobacter baumannii and Pseudomonas aeruginosa, and most of the specimen types were from sputum and secretions, and most of them were from respiratory and critical care diseases area and intensive care unit, among them, there are 78 strains of Acinetobacter baumannii studied this time. After screening, 78 Acinetobacter baumannii strains were resistant to Cefazolin, Ampicillin, Amoxicillin/Clavulanate, Aztreonam, Chloramphenicol, Tetracycline, Cefotaxime, Ampicillin/Sulbactam, Piperacillin, Gentamicin, Ciprofloxacin, Levofloxacin, Moxifloxacin, Cefepime, Ceftazidime, Piperacillin/Tazobactam, Compound Sulfonamide, Meropenem, Imipenem, Amikacin, Polymyxin, resistance rates were 98.72%, 98.72%, 96.16%, 96.15%, 96.15%, 66.67%, 60.26%, 58.98%, 58.97%, 57.69%, 57.69%, 57.69%, 57.69%, 57.69%, 56.41%, 55.13%, 53.85%, 52.56%, 52.56%, 50%, 0%. Among them, 17 strains with drug resistance gene blaOXA-51 were detected,accounting for 21.79%; drug gene blaOXA-23, blaOXA-24, blaIMP, blaOXA-58, blaSIM gene were not detected; 17 strains with virulence gene bfmS was detected, accounting for 21.79%; abaI, csuE virulence gene was not detected. ConclusionAcinetobacter baumannii in the hospital is highly resistant to carbapenems, mainly carrying blaOXA-51 resistance genes. Drug resistance is closely related to the virulence gene bfmS.

microbiology↗

Multi-scale observations of mangrove blue carbon fluxes; the NASA Carbon Monitoring System BlueFlux field campaign

The BlueFlux field campaign is supported by NASAs Carbon Monitoring System (CMS) and will develop prototype blue carbon products to inform coastal carbon management. Blue carbon is included in carbon-dioxide removal actions proposed to reduce atmospheric CO2 concentrations to mitigate climate change. Due to their high productivity and carbon storage, combined with historic losses and a wide-range of beneficial ecosystem services, the restoration and conservation of mangrove ecosystems features prominently in blue-carbon planning. The goal of BlueFlux is to carry out multi-scale measurements of CO2 and CH4 fluxes using chambers, flux towers, and aircraft and scale these to gridded products using space-based observations of forest structure and surface reflectance. The measurements cover gradients in disturbance, mainly from the history of hurricanes in the region that drive the dieback of mangroves and the formation of ghost forests. The fluxes of CH4 emissions will be contrasted with CO2 uptake to provide a more complete budget of radiative forcing and to understand the net climate benefits of blue carbon. BlueFlux demonstrates that quantifying the removals of CO2 and emissions of CH4 using a multi-scale approach can provide increased confidence in regional greenhouse-gas accounting, contribute to process-understanding, and help inform restoration and conservation efforts in the context of climate mitigation.

ecology↗

Type 17 Follicular Helper T (Tfh17) Cells are Superior for Memory Maintenance

A defining feature of successful vaccination is the ability to induce long-lived antigen- specific memory cells. Follicular helper T (Tfh) cells specialize in providing help to B cells in mounting protective humoral immunity in infection and after vaccination. Memory Tfh cells that retain the CXCR5 expression can confer protection through enhancing humoral response upon antigen re-exposure but how they are maintained is poorly understood. CXCR5+ memory Tfh cells in human blood are divided into Tfh1, Tfh2 and Tfh17 cells by the expression of chemokine receptors CXCR3 and CCR6 associated with Th1 and Th17 respectively. Here, we developed a new method to induce Tfh1, Tfh2 and Tfh17-like (iTfh1, iTfh2 and iTfh17) cells in vitro. Although all three iTfh subsets efficiently support antibody responses in recipient mice with immediate immunization, iTfh17 cells are superior to iTfh1 and iTfh2 cells in supporting antibody response to a later immunization after extended resting in vivo to mimic memory maintenance. Notably, the counterpart human Tfh17 cells are selectively enriched in CCR7+ central memory Tfh (TfhCM) with survival and proliferative advantages. Furthermore, the analysis of multiple human cohorts that received different vaccines for HBV, influenza virus, tetanus toxin or measles revealed that vaccine-specific Tfh17 cells outcompete Tfh1 or Tfh2 cells for the persistence in memory phase. Therefore, the complementary mouse and human results showing the advantage of Tfh17 cells in maintenance and memory function supports the notion that Tfh17-induced immunization might be preferable in vaccine development to confer long-term protection.

immunology↗

ATP6AP2-to-MMP14, a key pathway for osteoblast to osteocyte transition

Osteocytes, derived from osteoblast (OB)-lineage, occupy lacunae within bone matrix and exhibit unique morphology with dendrite-like projections to form an inter-connected network. Such a network is essential for osteocytes to monitor and orchestrate bone homeostasis. Thus, it is of considerable interest to investigate how osteocytes are formed and how they built the network. Here we provide evidence for ATP6AP2, an accessory subunit of V-ATPase, in OB-lineage cells to be critical for OB-to-osteocyte transition, and osteocyte distribution, maturation, and morphogenesis. Mice (ATP6AP2Ocn-Cre) that selectively deplete ATP6AP2 in OB-lineage cells results in altered osteocyte distribution and morphology, impaired osteocyte maturation and dendrite-like processes, increased osteocyte cell death and cortical woven bone formation. Further mechanistic studies identify MMP14 (matrix metalloproteinase-14) as a critical downstream of ATP6AP2 for osteocyte differentiation. ATP6AP2 interacts with MMP14 and promotes MMP14 surface distribution largely in immature- or osteoid-osteocytes, where this pathway regulates bone matrix remodeling and osteocyte differentiation. Expression of MMP14 into ATP6AP2 knock out OB-lineage cells in the mouse cortical bone could diminish the deficits in osteocyte maturation, dendrite-like process formation, and survival. These results thus demonstrate an un-recognized function of ATP6AP2 in promoting OB-to-osteocyte transition and uncover a pathway from ATP6AP2-to-MMP14 in osteocyte differentiation.

developmental biology↗

Additive and Dominant Loci Jointly Pyramiding the Grain Quality of Hybrid Rice

Hybrid rice has an advantage in its heterosis, resulting in high yield and resistance to biotic and abiotic stress. However, genetic improvement of grain quality is more challenging in hybrid rice than in inbred rice due to additional complexity, such as the dominant effect. It is critical to identify a path to efficiently develop inbreds and identify their superior crosses for hybrid production. Here, we developed a pipeline for joint analysis of phenotypes, effects, and generations (JPEG) and analysed 113 inbred varieties as male parents, five tester varieties as female parents, and their 565 (113x5) hybrid testcrosses for 12 grain quality traits, including grain length and width, chalkiness, and amylose content. A total of 1,619,588 single nucleotide polymorphisms were obtained for the parent varieties and inferred for the hybrids using whole-genome sequencing with an average sequencing depth of 11x. Genome-wide association studies with JPEG identified 128 loci associated with at least one of the 12 traits. There were 44 and 97 loci with additive and dominant effects, respectively, including 13 overlaps. Among the 128 associated loci, 42 loci are located in or near (<200 kb) 17 known genes. Pyramiding genetic loci with additive and/or dominant effects in genomic selection dramatically improves the accuracy of predicting hybrid performances. More than 45% of genetic variation was explained by the identified markers for all traits except one (30%). These results demonstrate that pyramiding genetically identified additive and dominant loci can afford substantial power for predicting hybrid performances, presenting opportunities to identify superior crosses from existing phenotypes and genotypes of inbreds and hybrids.

plant biology↗

Structure and dynamics of human disease-complication network

A complication is an unanticipated disease arisen following, induced by a disease, a treatment or a procedure. We compile the Human Disease-Complication Network from the medical data and investigate the characteristics of the network. It is observed that the modules of the network are dominated by the classes of diseases. The relations between modules are unveiled in detail. Three nontrivial motifs are identified from the network. We further simulate the dynamics of motifs with the Boolean dynamic model. Each motif represents a specific dynamic behavior, which is potentially functional in the disease system, such as generating temporal progressions and governing the responses to fluctuating external stimuli. Author summaryAdvances in molecular biology lead to a new discipline of network medicine, investigating human diseases in a networked structure perspective. Recently, clinical records have been introduced to the research of complex networks of diseases. An important available medical dataset that has been overlooked so far is the complications of diseases, which are vital for human beings. We compile the Human Disease-Complication Network, representing the causality between the upstream diseases and their downstream complications. This work not only helps us to comprehend why certain groups of diseases appear collectively, but also provides a new paradigm to investigate the dynamics of disease progression. For clinical applications, the investigation of complications may yield new approaches to disease prevention, diagnosis and treatment.

bioinformatics↗

Genomic hallmarks of cellular dormancy in cancer and therapeutic implications

Therapy resistance in cancer is often driven by a subpopulation of cells that are temporarily arrested in a non-proliferative G0 state, which is difficult to capture and whose mutational drivers remain largely unknown. We developed methodology to robustly identify this state from transcriptomic signals and characterised its prevalence and genomic constraints in solid primary tumours. We show that G0 arrest preferentially emerges in the context of more stable, less mutated genomes which maintain TP53 integrity and lack the hallmarks of DNA damage repair deficiency, while presenting increased APOBEC mutagenesis. We employ machine learning to uncover novel genomic dependencies of this process and validate the role of the centrosomal gene CEP89 as a modulator of proliferation/G0 arrest capacity. Lastly, we demonstrate that G0 arrest underlies unfavourable responses to various therapies exploiting cell cycle, kinase signalling and epigenetic mechanisms in single cell data, and propose a G0 arrest transcriptional signature that is linked with therapeutic resistance and can be used to further study and clinically track this state.

cancer biology↗

A CRISPR-Cas assisted shotgun mutagenesis method for evolutionary genome engineering

Genome mutagenesis drives the evolution of organisms. Here, we developed a CRISPR-Cas assisted random mutation (CARM) technology for whole genome mutagenesis. The method leverages an entirely random gRNA library and SpCas9-NG to randomly damage genomes in a controllable shotgun-like manner that then triggers diverse and abundant mutations via low-fidelity repair. As a proof-of-principle, CARM was applied to evolve the capacity of Saccharomyces cerevisiae BY4741 to produce {beta}-carotene. After seven rounds of iterative evolution over two months, a {beta}-carotene hyper-producing strain, C7-143, was isolated with a 10.5-fold increase in {beta}-carotene production and 857 diverse genomic mutants that comprised indels, duplications, inversions, and chromosomal rearrangements. Transcriptomic analysis revealed that the expression of 2,541 genes of strain C7-143 were significantly altered, suggesting that the metabolic landscape of the strain was deeply reconstructed. In addition, CARM was applied to evolve the industrially relevant Saccharomyces cerevisiae CEN.PK2-1C, the S-adenosyl-L-methionine production of which was increased to 2.28 times after just one round. Thus, CARM is a user-friendly and practical strategy for genetic remodeling and reverse engineering to investigate complicated organismal metabolism.

evolutionary biology↗

A high resolution single molecule sequencing-based Arabidopsis transcriptome using novel methods of Iso-seq analysis

BackgroundAccurate and comprehensive annotation of transcript sequences is essential for transcript quantification and differential gene and transcript expression analysis. Single molecule long read sequencing technologies provide improved integrity of transcript structures including alternative splicing, and transcription start and polyadenylation sites. However, accuracy is significantly affected by sequencing errors, mRNA degradation or incomplete cDNA synthesis. ResultsWe present a new and comprehensive Arabidopsis thaliana Reference Transcript Dataset 3 (AtRTD3). AtRTD3 contains over 160k transcripts - twice that of the best current Arabidopsis transcriptome and including over 1,500 novel genes. 79% of transcripts are from Iso-seq with accurately defined splice junctions and transcription start and end sites. We developed novel methods to determine splice junctions and transcription start and end sites accurately. Mis- match profiles around splice junctions provided a powerful feature to distinguish correct splice junctions and remove false splice junctions. Stratified approaches identified high confidence transcription start/end sites and removed fragmentary transcripts due to degradation. AtRTD3 is a major improvement over existing transcriptomes as demonstrated by analysis of an Arabidopsis cold response RNA-seq time-series. AtRTD3 provided higher resolution of transcript expression profiling and identified cold- and light-induced differential transcription start and polyadenylation site usage. ConclusionsAtRTD3 is the most comprehensive Arabidopsis transcriptome currently available. It improves the precision of differential gene and transcript expression, differential alternative splicing, and transcription start/end site usage from RNA-seq data. The novel methods for identifying accurate splice junctions and transcription start/end sites are widely applicable and will improve single molecule sequencing analysis from any species.

plant biology↗

Oct4 primarily controls enhancer activity rather than accessibility

The transcription factor Oct4 is essential for maintaining stem cell pluripotency and for efficient cell reprogramming, but its functional roles are far from being understood. Here, we investigate the functions of Oct4 by rapidly depleting Oct4 from mouse embryonic stem cells and conducting a time-resolved multiomics analysis. Oct4 depletion leads to an immediate loss of its binding to putative enhancers that are accessible in chromatin. Loss of Oct4 is accompanied by a concomitant decrease in mRNA synthesis from putative target genes that are part of the transcriptional network that maintains pluripotency. Oct4 binding to enhancers does not correlate with chromatin accessibility, whereas Sox2 can apparently retain accessibility after Oct4 depletion even in the absence of eRNA synthesis. These results are consistent with the model that Sox2 primarily acts as a pioneer factor that renders enhancers accessible, whereas Oct4 acts primarily as a transcriptional activator that stimulates transcription of pluripotency enhancers and their target genes.

genomics↗

Construction of continuously expandable single-cell atlases through integration of heterogeneous datasets in a generalized cell-embedding space

Computational tools for integrative analyses of diverse single-cell experiments are facing formidable new challenges including dramatic increases in data scale, sample heterogeneity, and the need to informatively cross-reference new data with foundational datasets. Here, we present SCALEX, a deep-learning method that integrates single-cell data by projecting cells into a batch-invariant, common cell-embedding space in a truly online manner (i.e., without retraining the model). SCALEX substantially outperforms online iNMF and other state-of-the-art non-online integration methods on benchmark single-cell datasets of diverse modalities, (e.g., scRNA-seq, scATAC-seq), especially for datasets with partial overlaps, accurately aligning similar cell populations while retaining true biological differences. We showcase SCALEXs advantages by constructing continuously expandable single-cell atlases for human, mouse, and COVID-19 patients, each assembled from diverse data sources and growing with every new data. The online data integration capacity and superior performance makes SCALEX particularly appropriate for large-scale single-cell applications to build-upon previously hard-won scientific insights.

bioinformatics↗

Oncogenic alterations in the p53 pathway abolish oscillatory competence

The tumor suppressor p53 displays concentration oscillations in response to DNA damage, a behavior that has been suggested to be essential to its anti-cancer function. Many genetic alterations in the p53 pathway have been shown to be oncogenic, whether by experiment or by clinical associations with various cancers. These oncogenic alterations include somatic mutations, copy number variations and inherited polymorphisms. Using a differential equation model of p53-Mdm2 dynamics, we employ Hopf bifurcation analysis to show that all of the oncogenic perturbations have a common effect, to abolish the oscillatory competence of p53, thereby impairing its tumor suppressor function. In this analysis, these diverse genetic alterations, widely observed in human cancers, have a unified mechanistic explanation. SignificanceIn human cancers, the p53 tumor suppressor pathway is frequently altered by diverse genetic changes. An integrated understanding of these oncogenic alterations is currently lacking. We show that all oncogenic alterations in the p53 pathway abolish the oscillatory competence of p53, a property that is essential for cell cycle arrest upon stress, for effective DNA damage response and for maintaining genome integrity. This unified dynamical explanation of distinct cancer driver events that converge on a key cancer hallmark pathway has practical implications for anti-cancer therapies.

systems biology↗

RIPK3 promoter hypermethylation in hepatocytes protects from bile acid induced inflammation and necroptosis

Background & AimsNecroptosis facilitates cell death in a controlled manner and is employed by many cell types following injury. It plays a major role in various liver diseases, albeit the cell type-specific regulation of necroptosis in the liver and especially hepatocytes has not yet been conceptualized. Approaches & ResultsHere, we demonstrate that DNA methylation suppresses RIPK3 expression in human hepatocytes and HepG2 cells. In diseases leading to cholestasis the RIPK3 expression is induced in mice and humans in a cell-type specific manner. Over-expression of RIPK3 in HepG2 cells leads immediately to RIPK3 activation by phosphorylation that is further modulated by different bile acids. ConclusionBile acids mediated RIPK3 activation facilitates the secretion and expression of IL-8 via the JNK-pathway, suggesting hepatocytes suppress RIPK3 expression to protect themselves from bile acid induced necroptosis and inflammation but in chronical liver diseases associated with cholestasis induction of RIPK3 expression may be an early event signaling danger and repair through release of IL-8. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=92 SRC="FIGDIR/small/426790v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1134cborg.highwire.dtl.DTLVardef@1a12063org.highwire.dtl.DTLVardef@15575a8org.highwire.dtl.DTLVardef@19f7596_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗