Biology subjects

Dai, C.

Publications and source records attributed to Dai, C..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Association between COVID-19 Disease Severity and T Cell Receptor Repertoire

During the COVID-19 pandemic, while most infected individuals experienced mild to moderate symptoms, a significant subset developed severe illness. A clinical test distinguishing between mild and severe cases could inform effective treatment strategies. Toward the latter stages of the pandemic, it became evident that vaccination or prior infection cannot entirely prevent reinfection. However, they are crucial in reducing the risk of severe disease by inducing T-cell memory. T cell receptors (TCRs), which can be obtained from human blood, serve as valuable biomarkers for monitoring T cell responses to SARS-CoV-2 infection. In this study, we investigated the associations between TCR metrics and COVID-19 severity and found significant associations. Furthermore, such associations could depend on the subset of TCRs used (e.g., TCRs from CD8+ T or CD4+ T cells) and when the TCRs were collected.

bioinformatics↗

bioRxiv2024

Interruption of glucagon signaling augments islet non-alpha cell proliferation in SLC7A2- and mTOR-dependent manners

ObjectiveDysregulated glucagon secretion and inadequate functional beta cell mass are hallmark features of diabetes. While glucagon receptor (GCGR) antagonism ameliorates hyperglycemia and elicits beta cell regeneration in pre-clinical models of diabetes, it also promotes alpha and delta cell hyperplasia. We sought to investigate the mechanism by which loss of glucagon action impacts pancreatic islet non-alpha cells, and the relevance of these observations in a human islet context. MethodsWe used zebrafish, rodents, and transplanted human islets comprising six different models of interrupted glucagon signaling to examine their impact on delta and beta cell proliferation and mass. We also used models with global deficiency of the cationic amino acid transporter, SLC7A2, and mTORC1 inhibition via rapamycin, to determine whether amino acid-dependent nutrient sensing was required for islet non-alpha cell growth. ResultsInhibition of glucagon signaling stimulated delta cell proliferation in mouse and transplanted human islets, and in mouse islets. This was rapamycin-sensitive and required SLC7A2. Likewise, gcgr deficiency augmented beta cell proliferation via SLC7A2- and mTORC1-dependent mechanisms in zebrafish and promoted cell cycle engagement in rodent beta cells but was insufficient to drive a significant increase in beta cell mass in mice. ConclusionOur findings demonstrate that interruption of glucagon signaling augments islet non-alpha cell proliferation in zebrafish, rodents, and transplanted human islets in a manner requiring SLC7A2 and mTORC1 activation. An increase in delta cell mass may be leveraged for future beta cell regeneration therapies relying upon delta cell reprogramming.

cell biology↗

bioRxiv2024

Proteogenomics analysis of human tissues using pangenomes

The genomics landscape is evolving with the emergence of pangenomes, challenging the conventional single-reference genome model. The new human pangenome reference provides an extra dimension by incorporating variations observed in different human populations. However, the increasing use of pangenomes in human reference databases poses challenges for proteomics, which currently relies on UniProt canonical/isoform-based reference proteomics. Including more variant information in human proteomes, such as small and long open reading frames and pseudogenes, prompts the development of complex proteogenomics pipelines for analysis and validation. This study explores the advantages of pangenomes, particularly the human reference pangenome, on proteomics, and large-scale proteogenomics studies. We reanalyze two large human tissue datasets using the quantms workflow to identify novel peptides and variant proteins from the pangenome samples. Using three search engines SAGE, COMET, and MSGF+ followed by Percolator we analyzed 91,833,481 MS/MS spectra from more than 30 normal human tissues. We developed a robust deep-learning framework to validate the novel peptides based on DeepLC, MS2PIP and pyspectrumAI. The results yielded 170142 novel peptide spectrum matches, 4991 novel peptide sequences, and 3921 single amino acid variants, corresponding to 2367 genes across five population groups, demonstrating the effectiveness of our proteogenomics approach using the recent pangenome references.

bioinformatics↗

bioRxiv2024

Driving proteomic imbalance to combat Neurofibromatosis type I (NF1)-associated malignancy

Unlike genomic instability, the role of proteomic instability in cancer remains poorly defined. Heat shock factor 1 (HSF1), a master regulator of the proteotoxic stress response, preserves proteome integrity under stress and is increasingly recognized as an oncogenic enabler. In Neurofibromatosis type I (NF1)-deficient malignant peripheral nerve sheath tumor (MPNST) cells, HSF1 loss induces widespread protein polyubiquitination, aggregation, and tumor-suppressive amyloidogenesis, yet is dispensable in non-transformed Schwann cells. Mechanistically, HSF1 protects the mitochondrial chaperone HSP60 from toxic soluble amyloid oligomers. To adapt to compromised protein quality, HSF1-deficient MPNST cells activate JNK to repress mTORC1-dependent translation, reducing protein load. Stimulating mTORC1 in these HSF1-deficient cells drives catastrophic proteomic imbalance, triggering pronounced cell death, in part through unchecked amyloidogenesis, and suppressing tumor growth in vivo. Thus, HSF1 safeguards the cancer proteome, enabling the oncogenic capacity of mTORC1. This proof-of-principle study establishes the induction of proteomic catastrophe as a new paradigm for combating malignancy.

cancer biology↗

bioRxiv2024

NK Cell Exhaustion in Wilson's Disease Revealed by Single-cell RNA Sequencing Predicts the Prognosis of Cholecystitis

Metabolic abnormalities associated with liver disease have a significant impact on the risk and prognosis of cholecystitis. However, the underlying mechanism is complicated and remains to be elucidated. In particular, the effect of metabolic abnormalities on the progression of cholecystitis through the regulation of immune cell function is poorly understood. In this study, we investigated this issue using Wilsons disease (WD) as a model. Wilsons disease is a genetic disorder characterized by impaired mitochondrial function and abnormal copper metabolism. Our retrospective clinical study of over 600 patients with WD found that they have a significantly higher incidence of cholecystitis and a poorer prognosis. The immune cell landscape in the hepatic mesenchymal stromal microenvironment of WD patients was shown using single-cell RNA. A major change is the constitution and function of the innate immune system, including enhanced antigen presentation process, activation of the immune response, and activation of lymphocytes. The proportion of mononuclear phagocytes and natural killer (NK) cells is increased, and the primary characteristic and function of macrophage, Kupffer cell, neutrophil, and NK cell are altered. Exhaustion of NK cell is the fundamental factor, supported by an increase in the expression of the inhibitory receptors KLRC1 and TIGIT and a decrease in the expression of cytotoxic molecules. Clinical tissue and blood samples verified increased KLRC1+ and TIGIT+ NK cells and decreased IFN{gamma}+ NK cells in WD. Further bioinformatic analysis has confirmed a positive correlation between NK cell exhaustion and poor prognosis in cholecystitis and other inflammatory diseases. The study demonstrated abnormal function of liver mesenchymal immune cells triggered by specific metabolic dysfunction in WD, with a focus on the correlation between NK cell exhaustion and poor healing of cholecystitis. Our findings highlight the immune cell dysfunction due to metabolic changes in hepatocytes and provide new insights into the improvement of inflammatory diseases by assessing immune cell function.

immunology↗

bioRxiv2024

Identification of a distinct cluster of GDF15high macrophages exhibiting anti-inflammatory activities

Macrophage-mediated inflammatory response may have crucial roles in the pathogenesis of a variety of human diseases. Growth differentiation factor 15 (GDF15) is a cytokine of the transforming growth factor-{beta} superfamily, with potential anti-inflammatory activities. Previous studies observed in human lungs some macrophages which expressed a high level of GDF15. In the present study, we employed multiple techniques, including immunofluorescence, flow cytometry, and single-cell RNA sequencing, in order to further clarify the identity of such GDF15high macrophages. We demonstrated that macrophages derived from human peripheral blood mononuclear cells and rat bone marrow mononuclear cells by in vitro differentiation with granulocyte-macrophage colony stimulating factor contained a minor population ([~]1%) of GDF15high cells. GDF15high macrophages did not exhibit a typical M1 or M2 phenotype, but had a unique molecular signature as revealed by single-cell RNA sequencing. Functionally, GDF15high macrophages were associated with reduced responsiveness to pro-inflammatory activation; furthermore, GDF15high macrophages could inhibit the pro-inflammatory functions of other macrophages via a paracrine mechanism. We further confirmed that GDF15 per se was a key mediator of the anti-inflammatory effects of GDF15high macrophage. Also, we provided direct evidence showing that GDF15high macrophages were also present in other macrophage-residing human tissues in addition to the lungs. Our results suggest that the GDF15high macrophage may represent a distinct cluster of macrophage cells with intrinsic anti-inflammatory functions. The (patho)physiological importance of these cells in vivo warrants further investigation.

immunology↗

bioRxiv2023

Pancreatic islet α cell function and proliferation requires the arginine transporter SLC7A2

Interrupting glucagon signaling decreases gluconeogenesis and the fractional extraction of amino acids by liver from blood resulting in lower glycemia. The resulting hyperaminoacidemia stimulates cell proliferation and glucagon secretion via a liver- cell axis. We hypothesized that cells detect and respond to circulating amino acids levels via a unique amino acid transporter repertoire. We found that Slc7a2ISLC7A2 is the most highly expressed cationic amino acid transporter in cells with its expression being three-fold greater in than {beta} cells in both mouse and human. Employing cell culture, zebrafish, and knockout mouse models, we found that the cationic amino acid arginine and SLC7A2 are required for cell proliferation in response to interrupted glucagon signaling. Ex vivo and in vivo assessment of islet function in Slc7a2-/- mice showed decreased arginine-stimulated glucagon and insulin secretion. We found that arginine activation of mTOR signaling and induction of the glutamine transporter SLC38A5 was dependent on SLC7A2, showing that boths role in cell proliferation is dependent on arginine transport and SLC7A2. Finally, we identified single nucleotide polymorphisms in SLC7A2 associated with HbA1c. Together, these data indicate a central role for SLC7A2 in amino acid-stimulated cell proliferation and islet hormone secretion.

physiology↗

bioRxiv2023

Immuno-Engineered Mitochondria for Efficient Therapy of Acute Organ Injuries via Modulation of Inflammation and Cell Repair

Acute organ injuries represent a major public health concern, and despite recent advances in organ support therapy, managing patients with organ failure stemming from such injuries remains a formidable challenge. The pathogenesis of acute organ injuries is driven by a cascade of inflammatory reactions and mitochondrial dysfunction-mediated cell damage, two interrelated events that fuel a vicious cycle of disease progression. In this study, we engineered neutrophil membrane-fused mitochondria (nMITO) that inherit the injury-targeting and broad-spectrum anti-inflammatory activities from neutrophil membrane proteins while retaining the cell-repairing activity of mitochondria. We demonstrated that nMITO can effectively block the inflammatory cascade and replenish mitochondrial function to simultaneously modulate these two key mechanisms in diverse acute organ injuries. Furthermore, by virtue of the {beta}-integrin inherited from neutrophils, nMITO exhibit selective homing to injured endothelial cells and can be efficiently delivered to damaged tissue cells via tunneling nanotubes, amplifying their regulatory effects on local inflammation and cell injury. In mouse models of acute myocardial injury, acute liver injury, and acute pancreatitis, nMITO effectively ameliorated immune dysfunction and repaired damaged tissues. Our findings suggest that nMITO represents a promising therapeutic strategy for managing acute organ injuries.

bioengineering↗

bioRxiv2023

Finite Element Modeling of Residual Hearing after Cochlear Implant Surgery in Chinchillas

Cochlear implant (CI) surgery is one of the most utilized treatments for severe hearing loss. However, the effects of a successful scala tympani insertion on the mechanics of hearing are not yet fully understood. This paper presents a finite element (FE) model of the chinchilla inner ear for studying the interrelationship between the mechanical function and the insertion angle of a CI electrode. This FE model includes a three-chambered cochlea and full vestibular system, accomplished using -MRI and -CT scanning technology. This models first application found minimal loss of residual hearing due to insertion angle after CI surgery and indicates that it is a reliable and helpful tool for future application in CI design, surgical planning, and stimuli setup.

bioengineering↗

bioRxiv2023

BnIR: a multi-omics collaborative resource and tool platform for Brassica napus biological study

In the post-GWAS era, multi-omics techniques have shown great power and potential for candidate gene mining and functional genomics research. However, due to the lack of effective data integration and multi-omics analysis platforms, such techniques have not still been applied widely in rapeseed, an important oil crop worldwide. Here, we constructed a rapeseed multi-omics database (BnIR; http://yanglab.hzau.edu.cn/BnIR), which provides datasets of six omics including genomics, transcriptomics, variomics, epigenetics, phenomics and metabolomics, as well as numerous "variation-gene expression-phenotype" associations by using multiple statistical methods. In addition, a series of multi-omics search and analysis tools are integrated to facilitate the browsing and application of these datasets. BnIR is the most comprehensive multi-omics database for rapeseed so far, and two case studies demonstrated its power to mine candidate genes associated with specific traits and analyze their potential regulatory mechanisms. Short SummaryIn this study, we developed BnIR (http://yanglab.hzau.edu.cn/BnIR), a multi-omics database for rapeseed that integrates six omics datasets and "variation-gene expression-phenotype" associations. The database is equipped with a range of multi-omics tools for streamlined browsing and analysis. Through multiple case studies, we demonstrated BnIRs potential to identify candidate genes associated with specific traits and investigate their regulatory mechanisms.

bioinformatics↗

bioRxiv2022

Disrupted RNA editing in beta cells mimics early stage type 1 diabetes

A major hypothesis for the etiology of type 1 diabetes (T1D) postulates initiation by viral infection, leading to double-stranded RNA (dsRNA)-mediated interferon response; however, a causal virus has not been identified. Here we use a mouse model, corroborated with human data, to demonstrate that endogenous dsRNA in beta-cells can lead to a diabetogenic immune response, thus identifying a virus-independent mechanism for T1D initiation. We found that disruption of the RNA editing enzyme ADAR in beta-cells triggers a massive interferon response, islet inflammation and beta-cell failure, with features bearing striking similarity to early-stage human T1D. Glycolysis via calcium enhances the interferon response, suggesting an actionable vicious cycle of inflammation and increased beta-cell workload. One sentence summaryAdar inactivation in beta-cells triggers a glucose-dependent interferon response causing insulitis and diabetes

cell biology↗

bioRxiv2022

MSdb: an integrated expression atlas of human musculoskeletal system

We introduce MSdb (https://www.msdb.org.cn), a database for visualization and integrated analysis of next-generation sequencing data from human musculoskeletal system, along with manually curated patient phenotype data. Systematic categorizing, standardized processing and freely accessible knowledge enables the reuse of public data. MSdb provides various types of analysis, including sample-level browsing of metadata information, gene/miRNA expression, and single-cell RNA-seq dataset. In addition, MSdb also allows integrated analysis for cross-samples and cross-omics analysis, including customized differentially-expressed gene/microRNA analysis, microRNA-gene network, scRNA-seq cross-sample/disease integration, and gene regulatory network analysis.

bioinformatics↗

bioRxiv2022

Shear and hydrostatic stress regulate fetal heart valve remodeling through YAP-mediated mechanotransduction

Clinically serious congenital heart valve defects arise from improper growth and remodeling of endocardial cushions into leaflets. Genetic mutations have been extensively studied but explain less than 20% of cases. Mechanical forces generated by beating hearts drive valve development, but how these forces collectively determine valve growth and remodeling remains incompletely understood. Here we decouple the influence of those forces on valve size and shape, and study the role of YAP pathway in determining the size and shape. The low oscillatory shear stress promotes YAP nuclear translocation in valvular endothelial cells (VEC), while the high unidirectional shear stress restricts YAP in cytoplasm. The hydrostatic compressive stress activated YAP in valvular interstitial cells (VIC), whereas the tensile stress deactivated YAP. YAP activation by small molecules promoted VIC proliferation and increased valve size. YAP inhibition suppressed the VIC proliferation and reduced valve size, but enhanced cell-cell adhesions between VEC thus maintaining an elongated shape. Finally, left atrial ligation was performed in chick embryonic hearts to manipulate the shear and hydrostatic stress in-vivo. The restricted flow in the left ventricle induced a globular and hypoplastic left atrioventricular (AV) valves with an inhibited YAP expression. By contrast, the right AV valves with sustained YAP expression grew and elongated normally. This study establishes a simple yet elegant mechanobiological system by which transduction of local stresses regulates valve growth and remodeling. This system guides leaflets to grow into proper sizes and shapes with the ventricular development, without the need of a genetically prescribed timing mechanism. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/517814v1_ufig1.gif" ALT="Figure 1"> View larger version (73K): org.highwire.dtl.DTLVardef@167b319org.highwire.dtl.DTLVardef@11f2f07org.highwire.dtl.DTLVardef@4894f1org.highwire.dtl.DTLVardef@12a66ab_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2022

Heat Shock Factor 1 (HSF1) specifically potentiates c-MYC-mediated transcription independently of the canonical heat-shock response

Despite its pivotal roles in biology, how the transcriptional activity of c-MYC is attuned quantitatively remain poorly defined. Here, we show that heat shock factor 1 (HSF1), the master transcriptional regulator of the heat-shock, or proteotoxic stress, response, acts as a key modifier of the c-MYC-mediated transcription. HSF1 deficiency diminishes c-MYC DNA binding and dampens its transcriptional activity genome-widely. Mechanistically, c-MYC, MAX, and HSF1 assemble into a transcription factor complex on genomic DNAs and, surprisingly, the DNA binding of HSF1 is dispensable. Instead, HSF1 physically recruits the histone acetyltransferase GCN5, thereby promoting histone acetylation and augmenting c-MYC transcriptional activity. Thus, our studies reveal that HSF1 specifically potentiates the c-MYC-mediated transcription, distinct from its role in the canonical heat-shock response. Importantly, this mechanism of action engenders two distinct c-MYC activation states, primary and advanced, which may be important to accommodate diverse physiological and pathological conditions.

cancer biology↗

bioRxiv2022

Metagenomics revealing molecular profiling of microbial community structure and metabolic capacity in Bamucuo, Tibet

We performed a survey of the microorganisms in Bamucuo, Tibet, resulting in 160,212 (soil) and 135,994 (water) contigs by shotgun metagenomic methods. We discovered 74 new bacterial species and reconstructed their draft genomes, which were obtained from the 75 reconstructed almost complete metagenomic assembly genomes (MAG) in the soil and water samples. Proteobacteria and Actinobacteria were found to be the most dominant bacterial phyla, while Euryarchaeota was the most dominant archaeal phylum. To our surprise, Pandoravirus salinus was found in the soil microbial community. We concluded that the microorganisms in Bamucuo fix carbon mainly through the 3-hydroxypropionic bi-cycle pathway. IMPORTANCEThe Qinghai-Tibet Plateau (QTP) is the highest plateau in the world, and the microorganisms there play vital ecological roles in the global biogeochemical cycle; however, detailed information on the microbial communities in QTP is still lacking, especially in high altitude areas above 4500 meters. This study, for the first time, characterized the microbial community composition and metabolic capacity in QTP high-altitude areas (with an altitude of 4,555 meters), confirmed that QTP is a huge and valuable resource bank in which more new non-resistant antibiotics and many other bioactive substances could be developed. In addition, the discovery of Pandoravirus salinus in the soil provides important information for further exploring this unique microorganism, and many draft genomes and the genome annotation information obtained in this study have laid the foundation for further in-depth study of the microbial ecology in Qinghai-Tibet Plateau.

microbiology↗

bioRxiv2022

Highly efficient multiplex genome editing in dicot plants using improved CRISPR/Cas systems

CRISPR/Cas9-mediated gene editing provides a powerful tool for dissecting gene function and improving important traits in crops. However, there are still persisting challenges to obtain high homozygous/bi-allelic (ho/bi) mutations in dicot plants. Here, we develop an improved CRISPR/Cas9 system harboring a calreticulin-like gene promoter, which can boost targeted mutations in dicots. Additionally, the pDC45_dsg construct, combining a 35Spro-tRNA_sgRNA-EU unit and PCE8pro-controlled Cas9, can achieve more than 80.0% ho/bi mutations at target sites in allotetraploid tobacco. We construct pDC45_Fast system that can simultaneously fulfill gene editing and shorten the life span of T0 generation tobacco and tomato. This study provides new tools for improving targeted gene mutagenesis in dicots, and makes manipulations of genes in Solanum more feasible.

plant biology↗

bioRxiv2021

RFX6-mediated dysregulation defines human β cell dysfunction in early type 2 diabetes

A hallmark of type 2 diabetes (T2D), a major cause of world-wide morbidity and mortality, is dysfunction of insulin-producing pancreatic islet {beta} cells1-3. T2D genome-wide association studies (GWAS) have identified hundreds of signals, mostly in the non-coding genome and overlapping {beta} cell regulatory elements, but translating these into biological mechanisms has been challenging4-6. To identify early disease-driving events, we performed single cell spatial proteomics, sorted cell transcriptomics, and assessed islet physiology on pancreatic tissue from short-duration T2D and control donors. Here, through integrative analyses of these diverse modalities, we show that multiple gene regulatory modules are associated with early-stage T2D {beta} cell-intrinsic defects. One notable example is the transcription factor RFX6, which we show is a highly connected {beta} cell hub gene that is reduced in T2D and governs a gene regulatory network associated with insulin secretion defects and T2D GWAS variants. We validated the critical role of RFX6 in {beta} cells through direct perturbation in primary human islets followed by physiological and single nucleus multiome profiling, which showed reduced dynamic insulin secretion and large-scale changes in the {beta} cell transcriptome and chromatin accessibility landscape. Understanding the molecular mechanisms of complex, systemic diseases necessitates integration of signals from multiple molecules, cells, organs, and individuals and thus we anticipate this approach will be a useful template to identify and validate key regulatory networks and master hub genes for other diseases or traits with GWAS data.

cell biology↗

bioRxiv2021

A proteomics sample metadata representation for multiomics integration, and big data analysis.

The amount of public proteomics data is increasing at an extraordinary rate. Hundreds of datasets are submitted each month to ProteomeXchange repositories, representing many types of proteomics studies, focusing on different aspects such as quantitative experiments, post-translational modifications, protein-protein interactions, or subcellular localization, among many others. For every proteomics dataset, two levels of data are captured: the dataset description, and the data files (encoded in different file formats). Whereas the dataset description and data file formats are supported by all ProteomeXchange partner repositories, there is no standardized format to properly describe the sample metadata and their relationship with the dataset files in a way that fully allows their understanding or re-analysis. It is left to the users choice whether to provide or not an ad hoc document containing this information. Therefore, in many cases, understanding the study design and data requires going back to the associated publication. This can be tedious and may be restricted in the case of non-open access publications. In many cases, this problem limits the generalization and reuse of public proteomics data. Here we present a standard representation for sample metadata tailored to proteomics datasets produced by the HUPO Proteomics Standards Initiative and supported by ProteomeXchange resources. We repurposed the existing data format MAGE-TAB used routinely in the transcriptomics field to represent and annotate proteomics datasets. MAGETAB-Proteomics defines a set of annotation rules that the datasets submitted to ProteomeXchange should follow, ranging from sample properties to data analysis protocols. We also introduce a crowdsourcing project that enabled the manual curation of over 200 public datasets using MAGE-TAB-Proteomics. In addition, we describe an ecosystem of tools and libraries that were developed to validate and submit sample metadata-related information to ProteomeXchange. We expect that these tools will improve the reproducibility of published results and facilitate the reanalysis and integration of public proteomics datasets.

bioinformatics↗