Search bioRxiv⌕ Search

Biology subjects

Liu, Q.

Publications and source records attributed to Liu, Q..

At least 343 records · Page 19Linked to original sources

Unified cross-modality integration and analysis of T-cell receptors and T-cell transcriptomes

Single-cell RNA sequencing and T-cell receptor sequencing (scRNA-seq and TCR-seq, respectively) technologies have emerged as powerful tools for investigating T-cell heterogeneity. However, the integrated analysis of gene expression profiles and TCR sequences remains a computational challenge. Herein, we present UniTCR, a unified framework designed for the cross-modality integration and analysis of TCRs and T-cell transcriptomes for a series of challenging tasks in computational immunology. By utilizing a dual-modality contrastive learning module and a single-modality preservation module to effectively embed each modality into a common latent space, UniTCR demonstrates versatility across various tasks, including single-modality analysis, modality gap analysis, epitope-TCR binding prediction and TCR profile cross-modality generation. Extensive evaluations conducted on multiple scRNA-seq/TCR-seq paired datasets showed the superior performance of UniTCR. Collectively, UniTCR is presented as a unified and extendable framework to tackle diverse T-cell-related downstream applications for exploring T-cell heterogeneity and enhancing the understanding of the diversity and complexity of the immune system.

bioinformatics↗

Genetically encoded transcriptional plasticity underlies stress adaptation in Mycobacterium tuberculosis

Transcriptional regulation is a critical adaptive mechanism that allows bacteria to respond to changing environments, yet the concept of transcriptional plasticity (TP) remains largely unexplored. In this study, we investigate the genome-wide TP profiles of Mycobacterium tuberculosis (Mtb) genes by analyzing 894 RNA sequencing samples derived from 73 different environmental conditions. Our data reveal that Mtb genes exhibit significant TP variation that correlates with gene function and gene essentiality. We also found that critical genetic features, such as gene length, GC content, and operon size independently impose constraints on TP, beyond trans-regulation. By extending our analysis to include two other Mycobacterium species -- M. smegmatis and M. abscessus -- we demonstrate a striking conservation of the TP landscape. This study provides a comprehensive understanding of the TP exhibited by mycobacteria genes, shedding light on this significant, yet understudied, genetic feature encoded in bacterial genomes.

microbiology↗

Tip60-mediated Rheb acetylation links palmitic acid with mTORC1 activation and insulin resistance

Differences in dietary fatty acid saturation impact glucose homeostasis and insulin sensitivity in vertebrates. Excess dietary intake of saturated fatty acids (SFAs) induces glucose intolerance and metabolic disorders. In contrast, unsaturated fatty acids (UFAs) elicit beneficial effects on insulin sensitivity. However, it remains elusive how SFAs and UFAs signal differentially toward insulin signaling to influence glucose homeostasis. Here, using a croaker model, we report that dietary palmitic acid (PA), but not oleic acid or linoleic acid, leads to dysregulation of mTORC1 signaling which provokes systemic insulin resistance and glucose intolerance. Mechanistically, using croaker primary myocytes, mouse C2C12 myotubes and HEK293T cells, we show that PA-induced mTORC1 activation is dependent on mitochondrial fatty acid {beta} oxidation. Notably, PA profoundly elevates acetyl-CoA derived from mitochondrial fatty acid {beta} oxidation which intensifies Tip60-mediated Rheb acetylation. Subsequently, the induction of Rheb acetylation facilitates hyperactivation of mTORC1 which enhances serine phosphorylation of IRS1 and simultaneously inhibits transcription of IRS1 through impeding TFEB nuclear translocation, leading to impairment of insulin signaling. Furthermore, targeted abrogation of acetyl-CoA produced from fatty acid {beta} oxidation or Tip60-mediated Rheb acetylation by pharmacological inhibition and genetic knockdown rescues PA-induced insulin resistance. Collectively, this study reveals a conserved acetylation-dependent mechanistic insight for understanding the link between fatty acids and insulin resistance, which may provide a potential therapeutic avenue to intervene in the development of T2D.

cell biology↗

Plasma Glycomic Markers of Accelerated Biological Aging During Chronic HIV Infection

People with HIV (PWH) experience an increased vulnerability to premature aging and inflammation-associated comorbidities, even when HIV replication is suppressed by antiretroviral therapy (ART). However, the factors that contribute to or are associated with this vulnerability remain uncertain. In the general population, alterations in the glycomes of circulating IgGs trigger inflammation and precede the onset of aging-associated diseases. Here, we investigate the IgG glycomes of cross-sectional and longitudinal samples from 1,216 women and men, both living with virally suppressed HIV and those without HIV. Our glycan-based machine learning models indicate that living with chronic HIV significantly accelerates the accumulation of pro-aging-associated glycomic alterations. Consistently, PWH exhibit heightened expression of senescence-associated glycan-degrading enzymes compared to their controls. These glycomic alterations correlate with elevated markers of inflammatory aging and the severity of comorbidities, potentially preceding the development of such comorbidities. Mechanistically, HIV-specific antibodies glycoengineered with these alterations exhibit reduced anti-HIV IgG-mediated innate immune functions. These findings hold significant potential for the development of glycomic-based biomarkers and tools to identify and prevent premature aging and comorbidities in people living with chronic viral infections.

microbiology↗

Fungal-bacteria interactions provide shelter for bacteria in Caesarean section scar diverticulum

Caesarean section scar diverticulum (CSD) is a significant cause of infertility among women who have previously had a Caesarean section, primarily due to persistent inflammatory exudation associated with this condition. Even though abnormal bacterial composition is identified as a critical factor leading to this chronic inflammation, clinical data suggests that a long-term cure is often unattainable with antibiotic treatment alone. In our study, we employed metagenomic analysis and mass spectrometry techniques to investigate the fungal composition in CSD and its interaction with bacteria. We discovered that local fungal abnormalities in CSD can disrupt the stability of the bacterial population and the entire microbial community by altering bacterial abundance via specific metabolites. For instance, Lachnellula suecica reduces the abundance of several Lactobacillus spp., such as Lactobacillus jensenii, by diminishing the production of metabolites like Goyaglycoside A and Janthitrem E. Concurrently, Clavispora lusitaniae and Ophiocordyceps australis can synergistically impact the abundance of Lactobacillus spp. by modulating metabolite abundance. Our findings underscore that abnormal fungal composition and activity are key drivers of local bacterial dysbiosis in CSD.

microbiology↗

Correlative single-cell X-ray tomography and X-ray fluorescence imaging

X-ray tomography (XRT) and X-ray fluorescence (XRF) imaging are two non-invasive imaging techniques to study cellular structures and chemical element distributions, respectively. However, correlative X-ray tomography and fluorescence imaging for the same cell have yet to be routinely realized due to challenges in sample preparation and X-ray radiation damage. Here we report an integrated experimental and computational workflow for achieving correlative multi-modality X-ray imaging of a single cell. The method consists of the preparation of radiation-resistant single-cell samples using live-cell imaging-assisted chemical fixation and freeze-drying procedures, targeting and labeling cells for correlative XRT and XRF measurement, and computational reconstruction of the correlative and multi-modality images. With XRT, cellular structures including the overall structure and intracellular organelles are visualized, while XRF imaging reveals the distribution of multiple chemical elements within the same cell. Our correlative method demonstrates the feasibility and broad applicability of using X-rays to understand cellular structures and the roles of chemical elements and related proteins in signaling and other biological processes.

cell biology↗

Neo-epitope identification by weakly-supervised peptide-TCR binding prediction

The identification of T cell neo-epitopes is fundamental and computational challenging in tumor immunotherapy study. As the binding of pMHC - T cell receptor (TCR) is the essential condition for neo-epitopes to trigger the cytotoxic T cell reactivity, several computational studies have been proposed to predict neo-epitopes from the perspective of pMHC-TCR binding recognition. However, they often failed with the inaccurate binding prediction for a single pMHC -TCR pair due to the highly diverse TCR space. In this study, we proposed a novel weakly-supervised learning framework, i.e., TCRBagger, to facilitate the personalized neo-epitope identification with weakly-supervised peptide-TCR binding prediction by bagging a sample-specific TCR profile. TCRBagger integrates three carefully designed learning strategies, i.e. a self-supervised learning strategy, a denoising learning strategy and a Multi-Instance Learning (MIL) strategy in the modeling of peptide-TCR binding. Our comprehensive tests revealed that TCRBagger exhibited great advances over existing tools by modeling interactions between peptide and TCR profiles. We further applied TCRBagger in different clinical settings, including (1) facilitating the peptide-TCR binding prediction under MIL using single-cell TCR-seq data. (2) improving the patient-specific neoantigen prioritization compared to the existing neoantigen identification tools. Collectively, TCRBagger provides novel perspectives and contributions for identifying neo-epitopes as well as discovering potential pMHC-TCR interactions in personalized tumor immunotherapy.

bioinformatics↗

ADAR2 inhibits ER-targeted mRNA translation via regulating nucleolar assembly of signal recognition particle

Adenosine-to-inosine RNA editing is mediated by ADAR family proteins and plays critical roles in regulating gene expression. Unlike other ADAR family members, ADAR2 mostly resides in nucleolus. The exact roles of this peculiar cellular distribution of ADAR2 is still largely unknown. Here, our current study unexpectedly uncovered that nucleoli-localized ADAR2 is involved in negatively regulating ER-targeted mRNA translation, which is mediated by SRP. Importantly, this regulation is not archived through direct binding of mRNA by ADAR2 or dependent on A-to-I editing of 7SL RNA. Further analysis indicated that ADAR2 directly interacts with SRP protein components, especially SRP68, in a RNA-independent manner and probably represses the SRP assembly. Hence, we proved insights into the novel functions of ADAR2 and long-lasting enigma about the peculiar translocation of SRP proteins into nucleoli during SRP biogenesis.

biochemistry↗

Ribosome subunit attrition and activation of the p53-MDM4 axis dominate the response of MLL-rearranged cancer cells to WDR5 WIN site inhibition

The chromatin-associated protein WD Repeat Domain 5 (WDR5) is a promising target for cancer drug discovery, with most efforts blocking an arginine-binding cavity on the protein called the "WIN" site that tethers WDR5 to chromatin. WIN site inhibitors (WINi) are active against multiple cancer cell types in vitro, the most notable of which are those derived from MLL-rearranged (MLLr) leukemias. Peptidomimetic WINi were originally proposed to inhibit MLLr cells via dysregulation of genes connected to hematopoietic stem cell expansion. Our discovery and interrogation of small molecule WIN site inhibitors, however, revealed that they act in MLLr cell lines to suppress ribosome protein gene (RPG) transcription, induce nucleolar stress, and activate p53. Because there is no precedent for an anti-cancer strategy that specifically targets RPG expression, we took an integrated multi-omics approach to further interrogate the mechanism of action of WINi in MLLr cancer cells. We show that WINi induce depletion of the stock of ribosomes, accompanied by a broad yet modest translational choke and changes in alternative mRNA splicing that inactivate the p53 antagonist MDM4. We also show that WINi are synergistic with agents including venetoclax and BET-bromodomain inhibitors. Together, these studies reinforce the concept that WINi are a novel type of ribosome-directed anti-cancer therapy and provide a resource to support their clinical implementation in MLLr leukemias and other malignancies.

cancer biology↗

The 14-3-3/spastin pathway coordinates neurite regeneration and recovery of spinal cord injury by targeting microtubule dynamics

Axon regeneration is abortive in the central nervous system following injury. Orchestrating microtubule dynamics has emerged as a promising approach to improve axonal regeneration. The microtubule severing enzyme spastin is essential for axonal development and regeneration through remodeling of microtubule arrangement. To date, however, little is known regarding the mechanisms underlying spastin action in neural regeneration after spinal cord injury. Here, we use glutathione transferase pulldown and immunoprecipitation assays to demonstrate that 14-3-3 interacts with spastin, both in vivo and in vitro, via spastin Ser233 phosphorylation. Moreover, we show that 14-3-3 protects spastin from degradation by inhibiting the ubiquitination pathway and upregulates the spastin-dependent severing ability. Furthermore, the 14-3-3 agonist Fusicoccin (FC-A) promotes neurite outgrowth and regeneration in vitro which needs spastin activation. Western blot and immunofluorescence results revealed that 14-3-3 protein is upregulated in the neuronal compartment after spinal cord injury in vivo. In addition, administration of FC-A not only promotes locomotor recovery, but also nerve regeneration following spinal cord injury in both contusion and lateral hemisection models; however, application of spastin inhibitor spastazoline successfully reverses these phenomena. Taken together, these results indicate that 14-3-3 is a molecular switch that regulates spastin protein levels, and the small molecule 14-3-3 agonist FC-A effectively mediates the recovery of spinal cord injury in mice which requires spastin participation. HighlightsO_LIThe formation of the 14-3-3 and spastin protein complex requires phosphorylation of spastin at the S233 site. C_LIO_LI14-3-3 is involved in the phosphorylation-ubiquitination crosstalk of spastin, thus impacting the protein stability. C_LIO_LI14-3-3 agonists Fusicoccin-A can facilitate the repair of spinal cord injury in mice. C_LIO_LIActivation of spastin function is a prerequisite for nerve regeneration and recovery of spinal cord injury in mice. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/550600v3_ufig1.gif" ALT="Figure 1"> View larger version (66K): org.highwire.dtl.DTLVardef@ebabb6org.highwire.dtl.DTLVardef@5651caorg.highwire.dtl.DTLVardef@113df6borg.highwire.dtl.DTLVardef@1b0ea5a_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

Deep learning-based cell profiling based on neuronal morphology

Treatment of neurons with {beta}-amyloid peptide (A{beta}1-42) has been widely used as a model to interrogate the cellular and molecular mechanisms underlying Alzheimers disease, and as an assay system to identify drugs that reverse or block disease phenotype. Prior studies have largely relied on high content imaging (HCI) to extract cellular features such as neurite length or branching, but these have not offered a robust/comprehensive means of relating readout to A{beta}1-42 concentrations. Here, we use a deep learning-based cell profiling technique to directly measure the impact of A{beta}1-42 on primary murine cortical neurons. The deep learning model achieved approximately 80% accuracy, compared to 54% for the cell phenotypic feature-based approach. The deep learning model could distinguish subtle neuronal morphological changes induced by a range of A{beta}1-42 concentration. When tested on a separate dataset, the accuracy remained comparable and dropped by only 2%. Our study demonstrates that deep learning-based cell profiling is superior to HCI-based feature extraction on neuronal morphology and it provides an alternative to a dose/response curve, where the modality of the response does not have to be pre-determined. Moreover, this approach could form the basis of a screening tool that can be applied to any cellular model where appropriate phenotypic markers based on genotypes and/or pathological insults are available.

bioinformatics↗

Sequencing 4.3 million mutations in wheat promoters to understand and modify gene expression

Wheat is an important contributor to global food security, and further improvements are required to feed a growing human population. New functional genetics and genomics tools can help us to understand the function of different genes and to engineer beneficial changes. In this study, we used a promoter capture assay to sequence 2-kb regions upstream of all high-confidence annotated genes from 1,513 mutagenized plants from the tetraploid wheat variety Kronos. We identified 4.3 million induced mutations with an accuracy of 99.8%, resulting in a mutation density of 41.9 mutations per kb. We also remapped Kronos exome capture reads to Chinese Spring RefSeq v1.1, identified 4.7 million mutations, and predicted their effects on annotated genes. Using these predictions, we identified 59% more non-synonymous substitutions and 49% more truncation mutations than in the original study. To show the biological value of the new promoter dataset, we selected two mutations within the promoter of the VRN-A1 vernalization gene. Both mutations, located within transcription factor binding sites, significantly altered VRN-A1 expression, and one reduced the number of spikelets per spike. These publicly available sequenced mutant datasets provide rapid and inexpensive access to induced variation in the promoters and coding regions of most wheat genes. These mutations can be used to understand and modulate gene expression and phenotypes for both basic and commercial applications, where limited governmental regulations can facilitate deployment. These mutant collections, together with gene editing, provide valuable tools to accelerate functional genetic studies in this economically important crop. Significance StatementWe sequenced 4.3 million induced mutations in the promoters and 4.7 million in the coding regions of most wheat genes. We also show how this public resource can be used to understand gene function, modulate gene expression, and generate changes in valuable wheat agronomic traits.

genomics↗

Analysis of small EV proteomes reveals unique functional protein networks regulated by VAP-A

Extracellular vesicles (EVs) influence cell phenotypes and functions via protein, nucleic acid and lipid cargoes. EVs are heterogeneous, due to diverse biogenesis mechanisms that remain poorly understood. Our previous study revealed that the endoplasmic rectiulum (ER) membrane contact site (MCS) linker protein VAP-A drives biogenesis of a subset of RNA-enriched EVs. Here, we examine the protein content of VAP-A-regulated EVs. Using label-free proteomics, we identified down- and up-regulated proteins in sEVs purified from VAP-A knockdown (KD) colon cancer cells. Gene set enrichment analysis (GSEA) of the data revealed protein classes that are differentially sorted to SEVs dependent on VAP-A. STRING protein-protein interaction network analysis of the RNA-binding protein (RBP) gene set identified several RNA functional machineries that are downregulated in VAP-A KD EVs, including ribosome, spliceosome, mRNA surveillance, and RNA transport proteins. We also observed downregulation of other functionally interacting protein networks, including cadherin-binding, unfolded protein binding, and ATP-dependent proteins. Significance of the studyLittle is known about biogenesis mechanisms that underlie EV heterogeneity. This study explores the protein repertoire of a specific subset of EVs that we recently identified to be generated at ER MCS and that are highly enriched in RNAs. We find that proteins from several classes of RNA machineries, including spliceosomes, are downregulated in EVs purified from cells knocked down for the ER MCS linker protein VAP-A. These data suggest that dynamic regulation of these protein machineries at ER MCS are involved in the sorting of RNA-RBP complexes into EVs.

cell biology↗

iPSC-Astrocyte morphology reflects patient clinical markers

Human iPSCs provide powerful cellular models of Alzheimers disease (AD) and offer many advantages over non-human models, including the potential to reflect variation in individual-specific pathophysiology and clinical symptoms Previous studies have demonstrated that iPSC-neurons from individuals with Alzheimers disease (AD) reflect clinical markers, including {beta}-amyloid (A{beta}) levels and synaptic vulnerability. However, despite neuronal loss being a key hallmark of AD pathology, many risk genes are predominantly expressed in glia, highlighting them as potential therapeutic targets. In this work iPSC-derived astrocytes were generated from a cohort of individuals with high versus low levels of the inflammatory marker YKL-40, in their cerebrospinal fluid (CSF). iPSC-derived astrocytes were treated with exogenous A{beta} oligomers and high content imaging demonstrated a correlation between astrocytes that underwent the greatest morphology change from patients with low levels of CSF-YKL-40 and more protective APOE genotypes. This finding was subsequently verified using similarity learning as an unbiased approach. This study shows that iPSC-derived astrocytes from AD patients reflect key aspects of the pathophysiological phenotype of those same patients, thereby offering a novel means of modelling AD, stratifying AD patients and conducting therapeutic screens. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/548687v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1df3486org.highwire.dtl.DTLVardef@f184d8org.highwire.dtl.DTLVardef@48a33dorg.highwire.dtl.DTLVardef@d53a90_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

EpiGePT: a Pretrained Transformer model for epigenomics

The inherent similarities between natural language and biological sequences have given rise to great interest in adapting the transformer-based large language models (LLMs) underlying recent breakthroughs in natural language processing (references), for applications in genomics. However, current LLMs for genomics suffer from several limitations such as the inability to include chromatin interactions in the training data, and the inability to make prediction in new cellular contexts not represented in the training data. To mitigate these problems, we propose EpiGePT, a transformer-based pretrained language model for predicting context-specific epigenomic signals and chromatin contacts. By taking the context-specific activities of transcription factors (TFs) and 3D genome interactions into consideration, EpiGePT offers wider applicability and deeper biological insights than models trained on DNA sequence only. In a series of experiments, EpiGePT demonstrates superior performance in a diverse set of epigenomic signals prediction tasks when compared to existing methods. In particular, our model enables cross-cell-type prediction of long-range interactions and offers insight on the functional impact of genetic variants under different cellular contexts. These new capabilities will enhance the usefulness of LLM in the study of gene regulatory mechanisms. We provide free online prediction service of EpiGePT through http://health.tsinghua.edu.cn/epigept/.

genomics↗

Deep spatial proteomic exploration of severe COVID-19-related pulmonary injury in post-mortem specimens

The lung, as a primary target of SARS-CoV-2, exhibits heterogeneous microenvironment accompanied by various histopathological changes following virus infection. However, comprehensive insight into the protein basis of COVID-19-related pulmonary injury with spatial resolution is currently deficient. Here, we generated a region-resolved quantitative proteomic atlas of seven major pathological structures within the lungs of COVID-19 victims by integrating histological examination, laser microdissection, and ultrasensitive proteomic technologies. Over 10,000 proteins were quantified across 71 dissected FFPE post-mortem specimens. By comparison with control samples, we identified a spectrum of COVID-19-induced protein and pathway dysregulations in alveolar epithelium, bronchial epithelium, and pulmonary blood vessels, providing evidence for the proliferation of transitional-state pneumocytes. Additionally, we profiled the region-specific proteomes of hallmark COVID-19 pulmonary injuries, including bronchiole mucus plug, pulmonary fibrosis, airspace inflammation, and hyperplastic alveolar type 2 cells. Bioinformatic analysis revealed the enrichment of cell-type and functional markers in these regions (e.g. enriched TGFBI in fibrotic region). Furthermore, we identified the up-regulation of proteins associated with viral entry, host restriction, and inflammatory response in COVID-19 lungs, such as FURIN and HGF. Collectively, this study provides spatial proteomic insights for understanding COVID-19-caused pulmonary injury, and may serve as a valuable reference for improving therapeutic intervention for severe pneumonia.

systems biology↗

Rapid identification of key genes for the rod-shaped morphology in bacteria using multi-species genomes

Accurate identification of key genes is pivotal in biological research. Here, we introduce machine learning to the field of functional gene identification, enabling precise prediction of bacterial shape based on genomic information. Our machine learning model successfully predicts bacterial shape, and we determine the influence of various protein domains on shape using the model. This approach facilitates the identification of candidate genes involved in regulating bacterial shape. Through targeted knockout experiments on eight potential key regulatory genes (pal, yicC, mreB, tolQ, ftsX, amiC, yddB, and rpoZ) in Escherichia coli, we observe significant alterations in rod-shaped morphology upon individual knockout of pal and mreB genes. E. coli transitions from rod-shaped to spherical or cell wall-deficient protoplasmic states. Experimental validations validate the robustness of our newly developed method. This study establishes an innovative avenue for exploring functional genes, harnessing large-scale genomic information to promptly uncover key genes governing shared traits across species.

genetics↗

Population structure can reduce clonal interference when sexual reproduction and dispersal are synchronized

In populations with limited recombination, clonal interference among beneficial mutations limits the maximum rate of adaptation. Spatial structure slows the spread of beneficial alleles; in purely asexual populations, this increases the amount of clonal interference. Beyond this extreme case, however, it is unclear how spatial structure and recombination interact to determine the amount of clonal interference. This interaction is particularly interesting because dispersal and recombination are often at least partially synchronized in natural populations, both at the individual and population levels, as when plants switch from vegetative growth to sexual reproduction or stress responses increase both motility and recombination in microbes. We simulate island models of populations evolving on a smooth fitness landscape and find that synchronized dispersal and sexual reproduction allow them to adapt faster than well-mixed populations of equal size. This is because the spatial structure preserves genetic diversity, while the synchronization increases the chance that recombination events occur between diverged individuals from different demes, i.e., the pairings where negative linkage disequilibrium can most effectively be reduced.

evolutionary biology↗