Biology subjects

Li, S.

Publications and source records attributed to Li, S..

At least 793 records · Page 44Linked to original sources

bioRxiv2022

Effects of cardiac function alterations on the risk of postoperative thrombotic complications in patients receiving endovascular aortic repair

Chronic heart disease (CHD) is a common comorbidity of patients receiving endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAA). The ventricular systolic function determines the hemodynamic environments in aorta, and thus regulating the formation of postoperative thrombus. However, the explicit relationship between ventricular systolic function and EVAR complication of thrombotic events is unknown. Here, we proposed a three-dimensional numerical model coupled with the lumped-elements heart model, which is capable of simulating thrombus formation in diverse systolic functions. The computational results demonstrate that thrombus tended to form on the interior side of the aorta arch and iliac branches, which is consistent with the four patients post-operative imaging follow-up. In addition, we found that the thrombus formation has negative correlations with the maximum ventricular contractile force (r=-0.2814{+/-}0.1012) and positive correlations with the minimum ventricular contractile force (r=0.238{+/-}0.074), whereas the effect of heart rate (r=-0.0148{+/-}0.1211) on thrombus formation is not significant. In conclusion, changes in ventricular systolic function may alter the risk of thrombotic events after EVAR repair, which could provide insight into the selection of adjuvant therapy strategies for AAA patients with CHD.

bioengineering↗

bioRxiv2022

Kinetic model derivation for design, building and operation of solid waste treatment unit based on system dynamics and computer simulation

Solid waste disposal is significantly important to maintain normal operation of both natural and artificial ecosystems. In this study, a kinetic model of solid waste treatment unit (SWTU) was upfront developed based on microbial ecology, system dynamics, cybernetics and digital simulation, which accurately described the relationships and interactions between solid waste decomposition (SWD) processes and biotic/abiotic factors. Then a specific SWTU prototype was designed and built from this kinetic model. A 370-day experiment demonstrated that SWTU maintained normal operation with robust stability and desired dynamic behaviors, and effectively disposed the solid waste. Therefore, this kinetic model was highly valid due to its high structural and behavioral similarity with the prototype. This research could lay a strong theoretical foundation for further closed-loop control and optimization of SWTU, and provide scientific guidance to environmental management and sustainable development.

ecology↗

bioRxiv2022

Robust identification of extrachromosomal DNA and genetic variants using multiple genetic abnormality sequencing (MGA-Seq)

Genomic abnormalities, including structural variation (SV), copy number variation (CNV), single-nucleotide polymorphism (SNP), homogenously staining regions (HSR) and extrachromosomal DNA (ecDNA), are strongly associated with cancer, rare diseases and infertility. A robust technology to simultaneously detect these genomic abnormalities is highly desired for clinical diagnosis and basic research. In this study, we developed a simple and cost-effective method - multiple genetic abnormality sequencing (MGA-Seq) - to simultaneously detect SNPs, CNVs, SVs, ecDNA and HSRs in a single tube. This method has been successfully applied in both cancer cell lines and clinical tumour samples and revealed that focal amplification in tumour tissue is substantially heterogeneous. Notably, we delineated the architecture of focal amplification and the ecDNA network by MGA-Seq, which facilitated the exploration of the regulation of gene expression in ecDNA. This method could be extensively applied for diagnosis and may greatly facilitate the investigation of the genomic mechanism for genetic diseases.

genomics↗

bioRxiv2022

Coupling of perinuclear actin cap and nuclear mechanics regulates flow-induced YAP spatiotemporal nucleocytoplasmic transport

Mechanical forces, including flow shear stress, regulate fundamental cellular process by modulating the nucleocytoplasmic transport of transcription factors, such as Yes-associated Protein (YAP). However, the mechanical mechanism how flow induces the nucleocytoplasmic transport remains largely unclear. Here we found that unidirectional flow applied to endothelial cells induces biphasic YAP nucleocytoplasmic transport with initial nuclear import, followed by nuclear export as perinuclear actin cap forms and nuclear stiffening in a dose and timing-dependent manner. In contrast, pathological oscillatory flow induces slight actin cap formation and nuclear softening, sustaining YAP nuclear localization. To explain the disparately spatiotemporal distribution of YAP, we developed a three-dimensional mechanochemical model considering coupling processes of flow sensing, cytoskeleton organization, nucleus mechanotransduction, and YAP spatiotemporal transport. We discovered that actin cap formation and nuclear stiffness alteration under flow synergically regulate nuclear deformation, hence governing YAP transport. Furthermore, we expanded our single cell model to a collective vertex framework and found that actin cap irregularities in individual cells under flow shear stress potentially induce topological defects and spatially heterogeneous YAP distribution in cellular monolayers. Our work unveils the unified mechanism of flow-induced nucleocytoplasmic transport, offering a universal linkage between transcriptional regulation and mechanical stimulation.

bioengineering↗

bioRxiv2022

DNAJB6 Isoform Specific Knockdown: Therapeutic Potential for LGMDD1

Dominant missense mutations in DNAJB6, an HSP40 co-chaperone, cause limb girdle muscular dystrophy (LGMD) D1. No treatments are currently available. Two isoforms exist, DNAJB6a and DNAJB6b, each with distinct localizations in muscle. Mutations reside in both isoforms, yet evidence suggests only DNAJB6b is responsible for disease pathogenesis. Mechanistic data supports either a toxic gain of function, a dominant negative mechanism, or a combination of both. Knockdown treatment strategies involving both isoforms carry risk as DNAJB6 knockout is embryonic lethal. We therefore developed an isoform specific knockdown approach using morpholinos. Selective reduction of each isoform was achieved in-vitro in primary mouse myotubes and human myoblasts, as well as in-vivo in mouse skeletal muscle. To assess isoform specific knockdown in LGMDD1, we created primary myotube cultures from a knock-in LGMDD1 mouse model. Using mass spectrometry, we identified an LGMDD1 protein signature related to protein homeostasis and myofibril structure. Selective reduction of DNAJB6b levels in LGMDD1 myotubes corrected much of the proteomic disease signature towards wild type levels. While additional in-vivo functional data is required, these findings suggest selective reduction of DNAJB6b may be a viable therapeutic target for LGMDD1.

neuroscience↗

bioRxiv2022

Functional gradients reveal altered functional segregation in patients with amnestic mild cognitive impairment and Alzheimer' s disease

BackgroundAlzheimers disease (AD) and amnestic mild cognitive impairment (aMCI) are associated with disrupted functional organization in brain networks, yet the finer changes in the topological organization in aMCI and AD remain to be investigated. Connectome gradients are a new tool representing brain functional topological organization in a low-dimensional space to smoothly capture the human macroscale hierarchy. MethodsHere, we examined altered topological organization in aMCI and AD by connectome gradient mapping. We further quantified functional segregation by gradient dispersion. Then, we systematically compared the alterations observed in aMCI and AD patients with those in normal controls (NCs) in a two-dimensional functional gradient space from both the whole-brain level and module level. ResultsCompared with NCs, the first gradient, which described the neocortical hierarchy from unimodal to transmodal regions, showed a distributed and significant suppression in AD patients, while abnormalities were only limited to local regions in aMCI patients. The second gradient showed a decreased pattern in the somatomotor module in both aMCI and AD patients. Furthermore, gradient dispersion showed significant decreases in AD patients at both the global level and module level, whereas this alteration was limited only to limbic areas in aMCI. Notably, we demonstrated that suppressed gradient dispersion in aMCI and AD patients was associated with cognitive scores. ConclusionsChanges in functional gradients could reflect different degrees of altered brain network segregation in aMCI and AD. These findings provide new evidence for altered brain hierarchy in aMCI and AD, which strengthens our understanding of the progressive mechanism of cognitive decline.

neuroscience↗

bioRxiv2022

CelltypeR: A framework to identify and characterize cell types in human midbrain organoids using flow cytometry

Motivated by the growing number of single cell RNA sequencing datasets (scRNAseq) revealing the cellular heterogeneity in complex tissues, particularly in brain and induced pluripotent stem cell (iPSC)-derived brain models, we developed a high-throughput, standardized approach for reproducibly characterizing cell types in complex neuronal tissues based on protein expression levels. Our approach combines a flow cytometry (FC) antibody panel targeting brain cells with a computational pipeline called CelltypeR, with functions for aligning and transforming datasets, optimizing unsupervised clustering, annotating and quantifying cell types, and statistical comparisons. We applied this workflow to human iPSC-derived midbrain organoids and identified the expected brain cell types, including neurons, astrocytes, radial glia, and oligodendrocytes. Defining gates based on the expression levels of our protein markers, we performed Fluorescence-Activated Cell Sorting of astrocytes, radial glia, and neurons, cell types were then confirmed by scRNAseq. Among the sorted neurons, we identified three subgroups of dopamine (DA) neurons; one reminiscent of substantia nigra DA neurons, the cell type most vulnerable in Parkinsons disease. Finally, we use our workflow to track cell types across a time course of organoid differentiation. Overall, our adaptable analysis framework provides a generalizable method for reproducibly identifying cell types across FC datasets.

neuroscience↗

bioRxiv2022

Breast cancer mutations HER2 V777L and PIK3CA H1047R activate the p21/CDK4/6/Cyclin D1 axis driving tumorigenesis and drug resistance.

In metastatic breast cancer, HER2 activating mutations frequently co-occur with mutations in the PIK3CA, TP53, or E-cadherin genes. Of these co-occurring mutations, HER2 and PIK3CA mutations are the most prevalent gene pair, with approximately 40% of HER2 mutated breast cancers also having activating mutations in PIK3CA. To study the effects of co-occurring HER2 and PIK3CA mutations, we bred genetically engineered mice with the HER2V777L; PIK3CAH1047Rtransgenes (HP mice) and studied the resulting breast cancers both in vivo as well as ex vivo using cancer organoids. HP breast cancers show accelerated tumor formation in vivo and increased invasion and migration in in vitro assays. HP breast cancers have resistance to the pan-HER tyrosine kinase inhibitor, neratinib, but are effectively treated by neratinib plus trastuzumab deruxtecan. Proteomic and RNA-Seq analysis of HP breast cancers showed increased gene expression of Cyclin D1 and p21WAF1/Cip1 and changes in cell cycle markers. Combining neratinib with CDK4/6 inhibitors was another effective strategy for HP breast cancers with neratinib plus palbociclib showing a statistically significant reduction in mouse HP tumors as compared to either drug alone. We validated both the neratinib plus trastuzumab deruxtecan and neratinib plus palbociclib combinations using a human breast cancer patient-derived xenograft that has very similar HER2 and PIK3CA mutations. Both of these drug combinations are being tested in phase 1 clinical trials and this study provides valuable preclinical evidence for them.

cancer biology↗

bioRxiv2022

High-resolution small RNAs landscape provides insights into alkane adaptation in the marine alkane-degrader Alcanivorax dieselolei B-5

Alkanes are widespread in the ocean, and Alcanivorax is one of the most ubiquitous alkane-degrading bacteria in the marine ecosystem. Small RNAs (sRNAs) are usually at the heart of regulatory pathways, but sRNA-mediated alkane metabolic adaptability still remains largely unknown due to the difficulties of identification. Here, differential RNA sequencing (dRNA-seq) modified with a size selection ([~]50-nt to 500-nt) strategy was used to generate high-resolution sRNAs profiling in the model species Alcanivorax dieselolei B-5 under alkane (n-hexadecane) and non-alkane (acetate) conditions. As a result, we identified 549 sRNA candidates at single-nucleotide resolution of 5-ends, with 63.4% of transcription start sites (TSSs) and 36.6% of processing sites (PSSs). These sRNAs originated from almost any locations in the genome, regardless of intragenic (65.8%), antisense (20.6%) and intergenic (6.2%) regions, and RNase E may function in the maturation of sRNAs. Most sRNAs locally distribute across the 15 reference genomes of Alcanivorax, and only 7.5% of sRNAs are broadly conserved in this genus. Expression responses to alkane of several core conserved sRNAs, including 6S RNA, M1 RNA and tmRNA, indicate that they may participate in alkane metabolisms and result in more actively global transcription, RNA processing and stresses mitigation. Two novel CsrA-related sRNAs are identified, which may be involved in the translational activation of alkane metabolism-related genes by sequestering the global repressor CsrA. The relationships of sRNAs with characterized genes of the alkane sensing (ompS), chemotaxis (mcp, cheR, cheW2), transporting (ompT1, ompT2, ompT3) and hydroxylation (alkB1, alkB2, almA) were created based on the genome-wide targets prediction. Overall, the sRNAs landscape lays the ground for uncovering cryptic regulations in the critical marine bacterium, among which both core and species-specific sRNAs are implicated in the alkane adaptive metabolisms.

microbiology↗

bioRxiv2022

Exosome-mediated viral nucleic acid presentation in a crustacean reveals innate immunity evolution from a novel perspective

As an enduring hot topic in the field of innate immunity, apoptosis is widely considered as an effective approach to eliminate pathogenic microbes, and possesses crucial role during host-pathogen interactions. Recently, researchers have found that virus-containing host cells could transmit apoptotic signals to surrounding uninfected cells during infection, but the mechanism remains unclear. Here, we found that exosomes secreted by WSSV-infected mud crab hemocytes contain viral nucleic acid wsv277, which could be transported to the recipient cells and further expressed viral protein with phosphokinase activity. Besides, by using transcriptome, proteome, ChIP-seq and coIP techniques, the results revealed that wsv277 could activate the transcription and translation of apoptotic genes via interacting with CBF and EF-1, so as to suppress the spread of virus infection by inducing apoptosis of the surrounding cells. Therefore, for the first time, our study proved that the components of DNA virus could be encapsulated into exosomes, and elucidated the mechanism of apoptotic signal transduction between cells from the perspective of exosome. Moreover, comparing those of invertebrates, we hypothesized that the innate immune system of vertebrate was weakened or degenerated, allowing exosomes to be employed by virus as the vehicle for immune escape. Significance statementOur study revealed that the components of DNA virus could be packaged and transmitted through the exosomes of lower invertebrates, which strongly demonstrated the diversity of exosome-mediated viral immunity and its universality in animals. Furthermore, we elucidated the mechanism of apoptotic signal transduction between cells from the perspective of exosome, and revealed a novel strategy for the host to cope with viral infection. Since exosome is an important innate immune regulation approach, we hypothesize that the innate immune system of vertebrates is weakened or degenerated, allowing exosomes to be employed by virus as the vehicle for immune escape.

immunology↗

bioRxiv2022

Complexes Formed by Mixing Tumor-derived Extracellular Vesicles with Polymeric Surfactants for Personalized Therapeutic Vaccine

The personalized therapeutic vaccine is an ideal weapon to eliminate tumors. However, the core steps of manufacturing personalized cancer vaccines are identifying tumor-specific antigens (TSAs, also called neoantigens) and HLA epitope prediction, which is time-consuming and labor-intense. Tumor-derived extracellular vesicles (TEVs) are alternative sources of neoantigens. However, the immunosuppressive nature of TEVs limits their application in such immunotherapy. In this study, we present a new strategy to maintain neoantigens in TEVs and diminish the immunosuppression by deconstructing the structure of TEVs with polymeric surfactant polyethylene glycol-phosphatidylethanolamine (PEG-PE). Together with adjuvant MPLA, the newly formed micelle-like complexes compose a therapeutic vaccine (MLC-V). Results show that MLC-V is capable of eliciting neoantigen-specific T-cell responses, restoring TEV-induced immunosuppression, and preventing lung metastasis of murine melanoma. MLC-V also exhibits outstanding anti-tumor efficacy in multiple tumor models. MLC-V can be used as a personalized therapeutic vaccine in a mimetic pre-clinical MC38 model and the anti-tumor effect of MLC-V was synergistically enhanced by PD-1 mAb. Taken together, the present study demonstrates a time-saving, low-cost, and simplified strategy to produce personalized therapeutic vaccines based on MLC-V platform technology.

immunology↗

bioRxiv2022

CRISPR/FnCas12a-mediated efficient multiplex and iterative genome editing in bacterial plant pathogens without donor DNA templates

CRISPR-based genome editing technology is revolutionizing prokaryotic research, but it has been rarely studied in bacterial plant pathogens. Here, we have developed a targeted genome editing method with no requirement of donor templates for convenient and efficient gene knockout in Xanthomonas oryzae pv. oryzae (Xoo), one of the most important bacterial pathogens on rice, by employing the heterogenous CRISPR/Cas12a from Francisella novicida and NHEJ proteins from Mycobacterium tuberculosis. FnCas12a nuclease generated both small and large DNA deletions at the target sites as well as it enabled multiplex genome editing, gene cluster deletion and plasmid cure in the Xoo PXO99A strain. Accordingly, a non-TAL effector-free polymutant strain PXO99AD25E, which lacks all 25 Xop genes involved in Xoo pathogenesis, has been engineered through iterative genome editing. Whole-genome sequencing analysis indicated that FnCas12a did not have a noticeable off-target effect. In addition, we revealed that these strategies are also suitable for targeted genome editing in another bacterial plant pathogen Pseudomonas syringae pv. tomato (Pst). We believe that our bacterial genome editing method will greatly expand the CRISPR study on microorganisms and advance our understanding of the physiology and pathogenesis of Xoo.

microbiology↗

bioRxiv2022

A pan-cancer PDX histology image repository with genomic and pathological annotations for deep learning analysis

Patient-derived xenografts (PDXs) model human intra-tumoral heterogeneity in the context of the intact tissue of immunocompromised mice. Histological imaging via hematoxylin and eosin (H&E) staining is performed on PDX samples for routine assessment and, in principle, captures the complex interplay between tumor and stromal cells. Deep learning (DL)-based analysis of large human H&E image repositories has extracted inter-cellular and morphological signals correlated with disease phenotype and therapeutic response. Here, we present an extensive, pan-cancer repository of nearly 1,000 PDX and paired human progenitor H&E images. These images, curated from the PDXNet consortium, are associated with genomic and transcriptomic data, clinical metadata, pathological assessment of cell composition, and, in several cases, detailed pathological annotation of tumor, stroma, and necrotic regions. We demonstrate that DL can be applied to these images to classify tumor regions and to predict xenograft-transplant lymphoproliferative disorder, the unintended outgrowth of human lymphocytes at the transplantation site. This repository enables PDX-specific, investigations of cancer biology through histopathological analysis and contributes important model system data that expand on existing human histology repositories. We expect the PDXNet Image Repository to be valuable for controlled digital pathology analysis, both for the evaluation of technical issues such as stain normalization and for development of novel computational methods based on spatial behaviors within cancer tissues.

bioinformatics↗

bioRxiv2022

An exploratory study of a simple approach for evaluating drug solubility in milk related vehicles

Milk related materials are frequently used as a vehicle for drug product administration. Therefore, drug solubility information in milk related vehicles is desirable for prediction of how they may influence in vivo drug release and bioavailability. However, there are very limited data published on this topic. This study explored a practical method to address the key challenges associated with solubility assessment in milk, including the sample equilibration time and cleanup procedures. Amitriptyline, acetaminophen, dexamethasone, nifedipine, piroxicam, and prednisolone were selected as model drugs to represent a wide range of physicochemical properties. Their solubilities were determined at room temperature in pH 6.8 phosphate buffer, skim milk, whole milk, reconstituted whole milk powder, and unprocessed raw milk. The overall results confirmed that milk greatly improves the solubility of poorly water-soluble drugs. However, the extent of improvement and mechanism of solubilization appeared unique for each drug, highlighting the importance of evaluating milk solubility experimentally. The method used in this exploratory study can be applied in future investigations of a broader range of drugs and milk-related vehicles.

biochemistry↗

bioRxiv2022

TEINet: a deep learning framework for prediction of TCR-epitope binding specificity

The adaptive immune response to foreign antigens is initiated by T-cell receptor (TCR) recognition on the antigens. Recent experimental advances have enabled the generation of a large amount of TCR data and their cognate antigenic targets, allowing machine learning models to predict the binding specificity of TCRs. In this work, we present TEINet, a deep learning framework that utilizes transfer learning to address this prediction problem. TEINet employs two separately trained encoders to transform TCR and epitope sequences into numerical vectors, which are subsequently fed into a fully connected neural network to predict their binding specificities. A major challenge for binding specificity prediction is the lack of a unified approach to sample negative data. Here, we first assess the current negative sampling approaches comprehensively and suggest that the Unified Epitope is the most suitable one. Subsequently, we compare TEINet with three baseline methods and observe that TEINet achieves an AUROC of 0.760, which outperforms baseline methods by 6.4-26%. Furthermore, we investigate the impacts of the pretraining step and notice that excessive pretraining can adversely affect model performance. Our results and analysis show that TEINet can make an accurate prediction using only the TCR sequence (CDR3{beta}) and the epitope sequence, providing novel insights to understand the interactions between TCRs and epitopes. TEINet is available at https://github.com/jiangdada1221/TEINet.

bioinformatics↗

bioRxiv2022

High performance genetically-encoded green fluorescent biosensors for intracellular L-lactate

L-Lactate is a monocarboxylate produced during the process of cellular glycolysis and has long been generally considered a waste product. However, studies in recent decades have provided new perspectives on the physiological roles of L-lactate as a major energy substrate and a signaling molecule. To enable further investigations of the physiological roles of L-lactate, we have developed a series of high-performance ({Delta}F/F = 15 to 30 in vitro), intensiometric, genetically-encoded green fluorescent protein (GFP)-based intracellular L-lactate biosensors with a range of affinities. We evaluated the performance of these biosensors by in vitro and live-cell characterization and demonstrated the utility with imaging applications in several cell lines.

bioengineering↗

bioRxiv2022

Development of an affinity-enhanced clinical candidate TCR targeting NY-ESO-1 with optimal potency and high specificity

The clinical success of T-cell receptor (TCR)-based immunotherapy depends on the efficacy and specificity of TCRs. Naturally occurring TCRs have limited anti-tumor potency due to their low affinity for tumor antigens. Affinity enhancement is a promising strategy to generate highly potent TCRs. However, it is concerned that affinity-enhanced TCRs are prone to lose specificity. We isolated low affinity TCRs specific for NY-ESO-1157-165/HLA-A*02:01 from peripheral blood mononuclear cells of healthy donors. An affinity-enhanced TCR candidate with optimal affinity and specificity was generated using phage display and an extensive set of in vitro and in vivo assays. Alanine scanning mutagenesis showed that the TCR candidate retained specificity by making extensive contacts to the side chains of NY-ESO-1157-165 peptide. Adoptive transfer of T cells engineered with this candidate (termed TAEST16001) significantly inhibited tumor growth in subcutaneous, metastatic, and patient-derived xenograft (PDX) mouse tumor models. This study demonstrates that sophisticated engineering and screening techniques can be utilized to generate a clinical candidate TCR with potent anti-tumor activity without losing specificity. TAEST16001 was approved by the Center for Drug Evaluation (CDE) as the first TCR-based immunotherapy clinical trial in China (ClinicalTrials.gov Identifier: NCT03159585).

immunology↗

bioRxiv2022

MR1-restricted T cell clonotypes are associated with 'resistance' to M.tuberculosis infection

T cells are required for a protective immune response against the human adapted pathogen Mycobacterium tuberculosis (M.tb). We recently described a cohort of Ugandan household contacts of tuberculosis cases that appear to resist M.tb infection (RSTRs) and showed that these individuals harbor IFN-{gamma} independent T cell responses to M.tb-specific peptide antigens. However, T cells also recognize non-protein antigens via antigen presenting systems that are independent of genetic background, leading to their designation as donor-unrestricted T (DURT) cells. We used combinatorial tetramer staining and multi-parameter flow cytometry to comprehensively characterize the association between DURTs and resistance to M.tb infection. We did not observe a difference in peripheral blood frequencies of invariant natural killer T (iNKT) cells, germline encoded mycolyl-reactive (GEM) T cells, or {gamma}{delta} T cells between RSTRs and matched controls with latent M.tb infection (LTBIs). However, we did observe a 1.65-fold increase in frequency of circulating MR1-restricted T (MR1T) cells among RSTRs in comparison with LTBI (p=0.03). Multi-modal single cell RNA-sequencing of 18,251 MR1T cells sorted from a subset of donors revealed 5150 clonotypes that expressed a common transcriptional program, the majority of which were private. Deep sequencing of the TCR- repertoire revealed several DURT clonotypes that were expanded among RSTRs, including at least two MR1T clonotypes. Taken together, our data reveal unexpected donor-specific diversity in the TCR repertoire of human MR1T cells as well as associations between MR1 clonotypes and resistance to M.tb infection.

immunology↗