Biology subjects

Ji, M.

Publications and source records attributed to Ji, M..

27 records · Page 2Linked to original sources

bioRxiv2020

The immunodominant and neutralization linear epitopes for SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) becomes a tremendous threat to global health. Although vaccines against the virus are under development, the antigen epitopes on the virus and their immunogenicity are poorly understood. Here, we simulated the three-dimensional structures of SARS-CoV-2 proteins with high performance computer, predicted the B cell epitopes on spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches, and then validated the epitope immunogenicity by immunizing mice. Almost all 33 predicted epitopes effectively induced antibody production, six of which were immunodominant epitopes in patients identified via the binding of epitopes with the sera from domestic and imported COVID-19 patients, and 23 were conserved within SARS-CoV-2, SARS-CoV and bat coronavirus RaTG13. We also found that the immunodominant epitopes of domestic SARS-CoV-2 were different from that of the imported, which may be caused by the mutations on S (G614D) and N proteins. Importantly, we validated that eight epitopes on S protein elicited neutralizing antibodies that blocked the cell entry of both D614 and G614 pseudo-virus of SARS-CoV-2, three and nine epitopes induced D614 or G614 neutralizing antibodies, respectively. Our present study shed light on the immunodominance, neutralization, and conserved epitopes on SARS-CoV-2 which are potently used for the diagnosis, virus classification and the vaccine design tackling inefficiency, virus mutation and different species of coronaviruses.

immunology↗

bioRxiv2020

Astrocytes express DMT1 and transferrin receptors, which transport iron thus activating Ca2+ signalling: possible role in neuroprotection against iron overload?

ABSTRACTIron is the fundamental element for numerous physiological functions. Reduced ferrous (Fe2+) and oxidized ferric (Fe3+) are the two ionized iron states in the living organisms. In the cell membrane, divalent metal ion transporter 1 (DMT1) is responsible for cellular uptake of Fe2+, whereas transferrin receptors (TFR) carry transferrin (TF)-bound Fe3+. In this study we performed, for the first time, detailed analysis of the action of Fe ions on cytoplasmic free calcium ion concentration ([Ca2+]i) in astrocytes. Using qPCR and immunocytochemistry we identified DMT1 and TFR in astrocytes in primary cultures, in acutely isolated astrocytes and in brain tissue preparations; in situ both DMT1 and TFR are concentrated in astroglial perivascular endfeet. Administration of Fe2+ or Fe3+ in low μM concentrations evoked Ca2+ signals in astrocytes in vitro and in vivo. Iron ions triggered increase in [Ca2+]i by acting through two distinct molecular cascades. Uptake of Fe2+ by DMT1 inhibited astroglial Na+-K+-ATPase (NKA), which led to an elevation in cytoplasmic Na+ concentration (as measured by SBFI probe), thus reversing Na+/Ca2+ exchanger (NCX) thereby generating Ca2+ influx. Uptake of Fe3+ by TF-TFR stimulated phospholipase C to produce inositol 1,4,5-trisphosphate (InsP3), thus trigering InsP3 receptor-mediated Ca2+ release from the endoplasmic reticulum. Iron-induced Ca2+ signals promote astroglial release of arachidonic acid and prostaglandin E2 cytokines by activating cytosolic phospholipase A2 (cPLA2) and NF-κB signalling cascade. In summary, these findings reveal new mechanisms of iron-induced astrocytic signalling operational in conditions of iron overload, in response to which astrocytes actively accumulate excessive iron and activate neuroprotective pathways.Competing Interest StatementThe authors have declared no competing interest.View Full Text

molecular biology↗

bioRxiv2020

Iatrogenic Iron Promotes Neurodegeneration and Activates Self-protection of Neural Cells against Exogenous Iron Attacks

Metal implants are used worldwide, with millions of metal nails, plates and fixtures grafted during orthopaedic surgeries. Iron is the most common element of these metal implants. As time passes metal elements can be corroded and iron can be released from the implants in the form of ferric (Fe3+) or ferrous (Fe2+). These iron ions can permeate the surrounding tissues and enter circulation; importantly both Fe3+ and Fe2+ freely pass blood brain barrier (BBB). Can iron from implants represent a risk factor for neurological diseases? This remains an unanswered question. In this study, we discovered that the probability of metal implants delivered through orthopaedic surgeries was higher in patients of Parkinsons diseases (PD) or ischemic stroke than in healthy subjects. This finding instigated subsequent study of iron effects on neuronal cells. In experiments in vivo, we found that iron selectively decreased presence of divalent metal transporter 1 (DMT1) in neurones through increasing the expression of Ndfip1, which degrades DMT1 and rarely exists in glial cells. At the same time iron accumulation increased expression of DMT1 in astrocytes and microglial cells and triggered reactive astrogliosis and microglial activation. Facing the attack of excess iron, glial cells act as neuroprotectors to uptake more extracellular iron by up-regulating DMT1, whereas neurones limit iron uptake through decreasing DMT1 operation. Cerebral accumulation of iron was associated with impaired cognition, locomotion and mood. Excess iron thus affects neural cells and could increase the risk of neurodegeneration.

neuroscience↗

bioRxiv2019

Modularized Transcriptional Regulatory Networks of Fusarium graminearum

The filamentous fungus Fusarium graminearum causes devastating crop disease and produces harmful mycotoxins worldwide. Understanding the complex F. graminearum transcriptional regulatory networks (TRNs) is vital for effective disease management. Reconstructing F. graminearum dynamic TRNs, an NP-hard problem, remains unsolved using commonly adopted reductionist or co-expression based approaches. Multi-omic data such as fungal genomic, transcriptomic data and phenomic data are vital to but so far have been largely isolated and untapped for unraveling phenotype-specific TRNs. Here for the first time, we harnessed these resources to infer global TRNs for F. graminearum using a Bayesian network based algorithm, "module networks". The inferred TRNs contain 49 regulatory modules that show condition-specific gene regulation. Through a robust validation based on prior biological knowledge including functional annotations and TF binding site enrichment, our network prediction displayed high accuracy and concordance with existing knowledge, highlighted by its accurate capture of the well-known trichothecene gene cluster. In addition, we developed a new computational method to calculate the associations between modules and phenotypes, and discovered subnetworks responsible for fungal virulence, sexual reproduction and mycotoxin production. Finally, we found a clear compartmentalization of TRN modules in core and lineage-specific genomic regions in F. graminearum, reflecting the evolution of the TRNs in fungal speciation. This system-level reconstruction of filamentous fungal TRNs provides novel insights into the intricate networks of gene regulation that underlie key processes in F. graminearum pathobiology and offers promise for the development of improved disease control strategies.

microbiology↗

bioRxiv2019

Genome-wide profiling of druggable active tumor defense mechanisms to enhance cancer immunotherapy

All current highly effective anti-tumor immunotherapeutics depend on the activity of T cells, but tumor cells can escape immune recognition by several mechanisms including loss of function in antigen presentation and inflammatory response genes, expression of immunomodulatory proteins and an immunosuppressive tumor microenvironment. In contrast, the comprehensive identification of strategies that sensitize tumor cells to immunotherapy in vivo has remained challenging. Here, we combine a two-cell type (2CT) whole-genome CRISPR-Cas9 screen with dynamic transcriptional analysis (DTA) of tumor upon T cell encounter to identify a set of genes that tumor cells express as an active defense against T cell-mediated killing. We then employed small molecule and biologic screens designed to antagonize gene products employed by tumor cells to actively defend against T cell-mediated tumor destruction and found that the inhibition of BIRC2, ITGAV or DNPEP enhanced tumor cell destruction by T cells. Mechanistically, we found that BIRC2 promoted immunotherapy resistance through inhibiting non-canonical NF-{kappa}B signaling and limiting inflammatory chemokine production. These findings show the path forward to improving T cell-mediated tumor destruction in the clinic.

immunology↗

bioRxiv2019

HIV-1 Nef interacts with LMP7 to attenuate immunoproteasome formation and MHC-I antigen presentation

AbstractProteasome is major protein degradation machinery and plays essential roles in diverse biological functions. Upon cytokine inductions, proteasome subunits {beta}1, {beta}2, and {beta}5 are replaced by {beta}1i/LMP2, {beta}2i/MECL-1, and {beta}5i/LMP7, leading to the formation of immunoproteasome. Immunoproteasome-degraded products are loaded onto the major histocompatibility complex class I (MHC-I) to regulate immune responses and induce cytotoxic-T-lymphocytes (CTLs). Human immunodeficiency virus type 1 (HIV-1) is the causal agent of acquired immunodeficiency syndrome (AIDS). HIV-1-specific CTLs represent critical immune responses to limit viral replication. HIV-1 negative regulatory factor (Nef) counteracts host immunity, especially the MHC-I/CTL. This study reveals a distinct mechanism by which Nef facilitates immune evasion through attenuating the functions of immunoproteasome and MHC-I. Nef interacts with LMP7 on the endoplasmic reticulum (ER) to down-regulate the incorporation of LMP7 into immunoproteasome, and thereby attenuating immunoproteasome formation. Moreover, Nef represses immunoproteasome protein degradation function, MHC-I trafficking, and antigen presentation activity.\n\nImportanceUbiquitin-proteasome system (UPS) is essential for degradation of damaged proteins, which takes place in proteasome. Upon cytokine inductions, proteasome catalytic activities are replaced by distinct isoforms resulting in formation of immunoproteasome. Immunoproteasome generates peptides for MHC-I antigen presentation and plays important roles in immune responses. HIV-1 is the agent of AIDS, and HIV-1-specific CTLs represent immune responses to limit viral replication. This study reveals a distinct mechanism by which HIV-1 promotes immune evasion. Viral protein Nef interacts with immunoproteasome component LMP7 to attenuate immunoproteasome formation and protein degradation function, and repress MHC-I antigen presentation activity. Therefore, HIV-1 targets LMP7 to inhibit immunoproteasome activation and LMP7 may be used as a target for the development of anti-HIV-1/AIDS therapy.

microbiology↗

bioRxiv2018

Variability in Sensory Sensitivity Predicts Motion Sickness in Virtual Reality

Severity of motion sickness varies across individuals. While some experience immediate symptoms, others seem relatively immune. We explored a potential explanation for such individual variability based on cue conflict theory. According to cue conflict theory, sensory signals that lead to mutually incompatible perceptual interpretations will produce physical discomfort. A direct consequence of such theory is that individuals with greater sensitivity to visual (or vestibular) sensory cues should show greater susceptibility, because they would be more likely to detect a conflict. Using virtual reality (VR), we first assessed individual sensitivity to a number of visual cues and subsequently induced moderate levels of motion sickness using stereoscopic movies presented in the VR headset. We found that an observers sensitivity to motion parallax cues predicted severity of motion sickness symptoms. We also evaluated evidence for another reported source of variability in motion sickness severity in VR, namely sex, but found little support. We speculate that previously-reported sex differences might have been due to poor personalization of VR displays, which default to male settings and introduce cue conflicts for the majority of females. Our results identify a sensory sensitivity-based predictor of motion sickness, which can be used to personalize VR experiences and mitigate discomfort.

neuroscience↗

bioRxiv2018

Effective soil extraction method for cultivating previously uncultured soil bacteria

Here, a new medium named as intensive soil extract medium (ISEM) based on new soil extract (NSE) using 80% ethanol was used to efficiently isolate previously uncultured bacteria and new taxonomic candidates, which accounted for 49% and 55% of the total isolates examined (n=258), respectively. The new isolates were affiliating with seven phyla such as Proteobacteria, Acidobacteria, Firmicutes, Actinobacteria, Verrucomicrobia, Planctomycetes, and Bacteroidetes. The result of chemical analysis showed that NSE included more diverse components of low-molecular-weight organic substances than two conventional soil extracts using distilled water. Cultivation of previously uncultured bacteria is expected to extend knowledge through the discovery of new phenotypic, physiological and functional properties, and even roles of unknown genes.\n\nIMPORTANCEEither metagenomics or single-cell sequencing can detect unknown genes from uncultured microbial strains in environments and may find their significant potential metabolites and roles. However, such gene/genome-based techniques still have a critical problem making impossible for further applications through cultivation. To solve this problem, various approaches for cultivation of uncultured bacteria have been developed, but they still have lack of skill to grow them on solid media for isolation and subculture.

microbiology↗

bioRxiv2018

Standardized Informatics Computing Platform for Advancing Biomedical Discovery Through Data Sharing

ObjectiveThe goal is to develop a standardized informatics computing system that can support end-to-end research data lifecycle management for biomedical research applications.\n\nMaterials and MethodsDesign and implementation of biomedical research informatics computing system (BRICS) is demonstrated. The system architecture is modular in design with several integrated tools: global unique identifier, validation, upload, download and query tools that support user friendly informatics system capability.\n\nResultsBRICS instances were deployed to support research for improvements in diagnosis of traumatic brain injury, biomarker discovery for Parkinsons Disease, the National Ophthalmic Disease Genotyping and Phenotyping network, the informatics core for the Center for Neuroscience and Regenerative Medicine, the Common Data Repository for Nursing Science, Global Rare Diseases Patient Registry, and National Institute of Neurological Disorders and Stroke Clinical Informatics system for trials and research.\n\nDiscussionData deidentification is conducted by using global unique identifier methodology. No personally identifiable information exists on the BRICS supported repositories. The Data Dictionary provides defined Common Data Elements and Unique Data Elements, specific to each of the BRICS instance that enables Query Tool to search through research data. All instances are supported by the Medical Imaging Processing, statistical analysis R, and Visualization software program.\n\nConclusionThe BRICS core modules can be easily adapted for various biomedical research needs thereby reducing cost in developing new instances for additional biomedical research needs. It provides user friendly tools for researchers to query and aggregate genetic, phenotypic, clinical and medical imaging data. Data sets are findable, accessible and reusable for researchers to foster new research on various diseases.

bioinformatics↗