Biology subjects

Sun, D.

Publications and source records attributed to Sun, D..

159 records · Page 9Linked to original sources

bioRxiv2019

The glycine locating at random coil of picornaviruses VP3 enhances viral pathogenicity by targeting p53 to promote apoptosis and autophagy

Picornaviruses, comprising important and widespread pathogens of humans and animals, have evolved to control apoptosis and autophagy for their replication and spread. However, the underlying mechanism of the association between apoptosis/autophage and viral pathogenicity remains unclear. In the present study, VP3 of picornaviruses was demonstrated to induce apoptosis and autophagy. Foot-and-mouth disease virus (FMDV), which served as a research model here, can strongly induce both apoptosis and autophagy in the skin lesions. By directly interacting with p53, FMDV-VP3 facilitates its phosphorylation and translocation, resulting in Bcl-2 family-mediated apoptosis and LC3-dependent autophagy. The single residue Gly129 of FMDV-VP3 plays a crucial role in apoptosis and autophagy induction and the interaction with p53. Consistently, the comparison of rescued FMDV with mutated Gly129 and parental virus showed that the Gly129 is indispensable for viral replication and pathogenicity. More importantly, the Gly129 locates at a bend region of random coil structure, the mutation of Gly to Ala remarkably shrunk the volume of viral cavity. Coincidentally, the Gly is conserved in the similarly location of other picornaviruses, including poliovirus (PV), enterovirus 71 (EV71), coxsackievirus (CV) and seneca valley virus (SVA). This study demonstrates that picornaviruses induce apoptosis and autophagy to facilitate its pathogenicity and the Gly is functional site, providing novel insights into picornavirus biology.

microbiology↗

bioRxiv2019

Precise annotation of human, chimpanzee, rhesus macaque and mouse mitochondrial genomes using 5’ and 3’ end small RNAs

Using 5 and 3 end small RNAs, we annotated human, chimpanzee, rhesus macaque and mouse mitochondrial genomes at 1 base-pair (bp) resolution to cover both strands of the mammalian mitochondrial genome entirely without leaving any gaps or overlaps. The precise annotation of all coding and non-coding genes (e.g. ncMT1, MDL2 and MDL1AS) led to the discovery of novel functions and mechanisms of mitochondrion. In this study, we defined the conserved sequence block (CSB) region to span five CSBs (CSB1, CSB2, CSB3, LSP and HSP) and identified the motifs of five CSBs in the mitochondrial displacement loop (D-loop) regions of 52 mammals. The conserved arrangement of these five CSBs in 17 primates inspired us to investigate the function of the mtDNA D-loop, which has been puzzling scientists for more than 50 years. We found that 5 sRNAs of MDL1AS control the expression levels of mitochondrial genes as a whole by a negative feedback mechanism. Thus, the precise annotations of three CSBs (CSB2, LSP and HSP) in more species will help to understand the function of the mtDNA D-loop. The precision annotation of animal mitochondrial genomes also provides abundant information for studying the molecular phylogenetics and evolution of animals.

bioinformatics↗

bioRxiv2019

Direct Metatranscriptome RNA-seq and Multiplex RT-PCR Amplicon Sequencing on Nanopore MinION - Promising Strategies for Multiplex Identification of Viable Pathogens in Food

Viable pathogenic bacteria are major biohazards that pose a significant threat to food safety. Despite the recent developments in detection platforms, multiplex identification of viable pathogens in food remains a major challenge. A novel strategy is developed through direct metatranscriptome RNA-seq and multiplex RT-PCR amplicon sequencing on Nanopore MinION to achieve real-time multiplex identification of viable pathogen in food. Specifically, this study reports an optimized universal Nanopore sample extraction and library preparation protocol applicable to both Gram-positive and Gram-negative pathogenic bacteria, demonstrated using a cocktail culture of E. coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes, which were selected based on their impact on economic loss or prevalence in recent outbreaks. Further evaluation and validation confirmed the accuracy of direct metatranscriptome RNA-seq and multiplex RT-PCR amplicon sequencing using Sanger sequencing and selective media. The study also included a comparison of different bioinformatic pipelines for metatranscriptomic and amplicon genomic analysis. MEGAN without rRNA mapping showed the highest accuracy of multiplex identification using the metatranscriptomic data. EPI2ME also demonstrated high accuracy using multiplex RT-PCR amplicon sequencing. In addition, a systemic comparison was drawn between Nanopore sequencing of the direct metatranscriptome RNA-seq and RT-PCR amplicons. Both methods are comparable in accuracy and time. Nanopore sequencing of RT-PCR amplicon has higher sensitivity, but Nanopore metatranscriptome sequencing excels in read length and dealing with complex microbiome and non-bacterial transcriptome backgrounds. To the best of our knowledge, this is the first report of metatranscriptome sequencing of cocktail microbial RNAs on the emerging Nanopore platform. Direct RNA-seq and RT-PCR amplicons sequencing of metatranscriptome enable the direct identification of nucleotide analogs in RNAs, which is highly informative for determining microbial identities while detecting ecologically relevant processes. The information pertained in this study could be important for future revelatory research, including predicting antibiotic resistance, elucidating host-pathogen interaction, prognosing disease progression, and investigating microbial ecology, etc.

microbiology↗

bioRxiv2019

A Systems Immunology Approach Identifies Cytokine-Induced STAT Signaling Pathways Critical to Rheumatoid Arthritis Disease Activity and Treatment Response

Rheumatoid arthritis (RA), a chronic autoimmune disease characterized by circulating autoantibodies, involves many cytokine-mediated signaling pathways in multiple immune cell subsets. Most studies of immune cells in RA have limitations, such as analysis of a small number of cell subsets or pathways, and limited longitudinal data on patient phenotypes. In this study, we used an innovative systems immunology approach to simultaneously quantify up to 882 signaling nodes (Jak/STAT signaling readouts modulated by cytokines and other stimuli) in 21 immune cell subsets. We studied 194 RA patients and 41 controls, including 146 well-characterized RA patients prior to, and 6 months after, initiation of methotrexate or biologic agents from the Treatment Efficacy and Toxicity in RA Database and Repository (TETRAD). There was strikingly attenuated signaling capacity in RA patients in IFN stimulation followed by measurement of phosphorylated STAT1 [IFN[->]p-STAT1] in six immune cell subsets. Multiple nodes showed negative association with disease activity, including IFN[->]STAT5 signaling in naive and memory B cells. In contrast, IL-6-induced STAT1 and STAT3 activation in central memory CD4-negative T cells showed a positive association with disease activity. Multiple nodes were associated with treatment response, including IFN[->]STAT1 in monocytes and IL-6[->]STAT3 in CD4+ naive T cells. Decision tree analysis identified a model combining these two nodes as a high-performing classifier of treatment response to TNF inhibitors. Our study provides novel information on RA disease mechanisms and serves as a framework for the discovery and validation of biomarkers of treatment response in RA.

immunology↗

bioRxiv2019

Branched-Chain Amino Acid Metabolic Reprogramming Orchestrates Drug Resistance to EGFR Tyrosine Kinase Inhibitors

Drug resistance is a significant hindrance to effective cancer treatment. Although resistance mechanisms of epidermal growth factor receptor (EGFR)-mutant cancer cells to lethal EGFR tyrosine kinase inhibitors (TKI) treatment have been investigated intensively, how cancer cells orchestrate adaptive response under sublethal drug challenge remains largely unknown. Here we find that 2-hour sublethal TKI treatment elicits a transient drug-tolerant state in EGFR-mutant lung cancer cells. Continuous sublethal treatment reinforces this tolerance and eventually establishes long-term TKI resistance. This adaptive process involves H3K9 demethylation-mediated epigenetic upregulation of branched-chain amino acid aminotransferase 1 (BCAT1) and subsequent metabolic reprogramming, which promotes TKI resistance through attenuating reactive oxygen species (ROS) accumulation. Combinational treatment with TKI and ROS-inducing reagents overcomes this drug resistance in preclinical mouse models. Clinical information analyses support the correlation of BCAT1 expression with EGFR TKI response. Collectively, our findings reveal the importance of epigenetically regulated BCAT1-engaged metabolism reprogramming in TKI resistance in lung cancer.\n\nHIGHLIGHTSSublethal EGFR TKI treatment induces transient drug-tolerant state and long-term resistance in EGFR-mutant lung cancer cells\n\nEpigenetically regulated BCAT1-mediated metabolic reprogramming orchestrates EGFR TKI-induced drug resistance\n\nCombinational treatment with TKI and ROS-inducing agents overcomes the drug resistance induced by EGFR TKI treatment

cancer biology↗

bioRxiv2019

Threat-Induced Anxiety During Goal Pursuit Disrupts Amygdala-Prefrontal Cortex Connectivity in Posttraumatic Stress Disorder

To investigate how unpredictable threat during goal pursuit impacts fronto-limbic activity and functional connectivity in posttraumatic stress disorder (PTSD), we compared military veterans with PTSD (n=25) versus trauma-exposed Control (n=25). Participants underwent functional magnetic resonance imaging (fMRI) while engaged in a computerized chase-and-capture game task that involved optimizing monetary rewards obtained from capturing virtual prey while simultaneously avoiding capture by virtual predators. The game was played under two alternating contexts - one involving exposure to unpredictable, task-irrelevant threat by randomly occurring electrical shocks, and a nonthreat control condition. Activation in and functional connectivity between the amygdala and ventromedial prefrontal cortex (vmPFC) was tested across threat and nonthreat task contexts with generalized psychophysiological interaction (gPPI) analyses. PTSD patients reported higher anxiety than controls across contexts. Better task performance represented by successfully avoiding capture by predators under threat than nonthreat contexts was associated with stronger left amygdala-vmPFC functional connectivity in controls and greater vmPFC activation in PTSD patients. PTSD symptom severity was negatively correlated with vmPFC activation in trauma-exposed controls and with right amygdala-vmPFC functional connectivity across all participants in the threat relative to nonthreat contexts. The findings showed that veterans with PTSD have disrupted amygdala-vmPFC functional connectivity and greater localized vmPFC processing under threat-modulation of goal-directed behavior, specifically related to successful task performance while avoiding loss of monetary rewards. In contrast, trauma survivors without PTSD rely on stronger threat-modulated left amygdala-vmPFC functional connectivity during goal-directed behavior, which may represent a resilience-related functional adaptation.

neuroscience↗

bioRxiv2019

Pharmacokinetics Modeling and Simulation of Voriconazole Dosing and Safety in Patients with Liver Cirrhosis

Voriconazole is used to treat invasive fungal disease and the optimal dose regimens are still unknown in cirrhotic Patients. The aim of this study was to determine the safety, to describe pharmacokinetics characteristics, and to optimize dosage regimens of voriconazole in cirrhotic patients. Data pertaining to voriconazole were collected retrospectively and analyzed using a population pharmacokinetics model. A total of 219 trough concentrations (Cmin) from 120 patients were analyzed. Voriconazole-related adverse events developed in 29 patients, with 69.0% of AEs developing within the first week after voriconazole treatment. The threshold Cmin for AEs was 5.12 mg/L. A one-compartment model with first-order absorption and elimination adequately described the data. The Child-Pugh class was the only covariate in final model. Voriconazole clearance in patients with Child-pugh A and B cirrhosis (CP-A/CP-B) and Child-pugh C cirrhosis (CP-C) were 1.79 L/h and 0.99 L/h, respectively, the volume of distribution was 159.6 L, and the oral bioavailability was 91.8%. The elimination half-life was significantly extended for up to 61.8 - 111.7 h in cirrhotic patients. Model-based simulations showed that the appropriate maintenance doses are 75 mg/12 h and 150 mg/24 h intravenously or orally for CP-A/CP-B patients, and 50 mg/12 h and 100 mg/24 h intravenously or orally for CP-C patients. The results support voriconazole maintenance doses in LC patients should be reduced to one-fourth for CP-C patients and to one-third for CP-A/CP-B patients compared to that for patients with normal liver function. Monitoring Cmin early could be a useful strategy to ensure the safety.

pharmacology and toxicology↗

bioRxiv2018

Mechanism and resistance for antimycobacterial activity of a fluoroquinophenoxazine compound

We have previously reported the inhibition of bacterial topoisomerase I activity by a fluoroquinophenoxazine compound (FP-11g) with a 6-bipiperidinyl lipophilic side chain that exhibited promising antituberculosis activity (MIC = 2.5 M against Mycobacterium tuberculosis, SI = 9.8). Here, we found that the compound is bactericidal towards Mycobacterium smegmatis, resulting in greater than 5 Log10 reduction in colony-forming units [cfu]/mL following a 10 h incubation at 1.25 M (4X MIC) concentration. Growth inhibition (MIC = 50 M) and reduction in cfu could also be observed against a clinical isolate of Mycobacterium abscessus. Stepwise isolation of resistant mutants of M. smegmatis was conducted to explore the mechanism of resistance. Mutations in the resistant isolates were identified by direct comparison of whole-genome sequencing data from mutant and wild-type isolates. These include mutations in genes likely to affect the entry and retention of the compound. FP-11g inhibits Mtb topoisomerase I and Mtb gyrase with IC50 of 0.24 and 31.5 M, respectively. Biophysical analysis showed that FP-11g binds DNA as an intercalator but the IC50 for inhibition of Mtb topoisomerase I activity is >10 fold lower than the compound concentrations required for producing negatively supercoiled DNA during ligation of nicked circular DNA. Thus, the DNA-binding property of FP-11g may contribute to its antimycobacterial mechanism, but that alone cannot account for the observed inhibition of Mtb topoisomerase I.

microbiology↗

bioRxiv2018

Spatial and Temporal Analysis of the Stomach and Small Intestinal Microbiota in Fasted Healthy Humans

Although the microbiota in the proximal gastrointestinal (GI) tract has been implicated in health and disease, much of these microbes remains understudied compared to the distal GI tract. This study characterized the microbiota across multiple proximal GI sites over time in healthy individuals.\n\nAs part of a study of the pharmacokinetics of oral mesalamine administration, healthy, fasted volunteers (N=8; 10 observation periods total) were orally intubated with a four-lumen catheter with multiple aspiration ports. Samples were taken from stomach, duodenal, and multiple jejunal sites, sampling hourly ([≤]7 hours) to measure mesalamine (administered at t=0), pH, and 16S rRNA gene-based composition.\n\nWe observed a predominance of Firmicutes across proximal GI sites, with significant variation compared to stool. The microbiota was more similar within individuals over time than between subjects, with the fecal microbiota being unique from that of the small intestine. The stomach and duodenal microbiota displayed highest intra-individual variability compared to jejunal sites, which were more stable across time. We observed significant correlations in the duodenal microbial composition with changes in pH; linear mixed models identified positive correlations with multiple Streptococcus operational taxonomic units (OTU) and negative correlations with multiple Prevotella and Pasteurellaceae OTUs. Few OTUs correlated with mesalamine concentration.\n\nThe stomach and duodenal microbiota exhibited greater compositional dynamics compared to the jejunum. Short-term fluctuations in the duodenal microbiota was correlated with pH. Given the unique characteristics and dynamics of the proximal GI tract microbiota, it is important to consider these local environments in health and disease states.

microbiology↗

bioRxiv2018

Resting-State Brain Fluctuation and Functional Connectivity Dissociate Moral Injury from Posttraumatic Stress Disorder

Moral injury is closely associated with posttraumatic stress disorder (PTSD) and is characterized by disturbances in social and moral cognition. Little is known about the neural underpinnings of moral injury, and whether the neural correlates are different between moral injury and PTSD.\n\nA sample of 26 US military veterans (2 females; 28~55 years old) were investigated to determine how moral injury experiences and PTSD symptoms are differentially related to spontaneous fluctuations indexed by low frequency fluctuation (ALFF) as well as functional connectivity during resting-state functional magnetic resonance imaging (fMRI) scanning.\n\nALFF in the left inferior parietal lobule (L IPL) was positively associated with moral injury sub-scores of transgressions, negatively associated with sub-scores of betrayals, and not related with PTSD symptoms. Moreover, functional connectivity between the L IPL and bilateral precuneus was positively related with PTSD symptoms and negatively related with moral injury total scores.\n\nOur results provide the first evidence that moral injury and PTSD have dissociable neural underpinnings, and behaviorally distinct sub-components of moral injury are different in neural responses. The findings increase our knowledge of the neural distinctions between moral injury and PTSD and may contribute to developing nosology and interventions for military veterans afflicted with moral injury.

neuroscience↗

bioRxiv2018

Tau accumulation activates STAT1 triggering memory deficits via suppressing NMDA receptor expression

Intracellular tau accumulation forming neurofibrillary tangles is hallmark pathology of Alzheimer's disease (AD), but how tau accumulation induces synapse impairment is elusive. By overexpressing human full-length wildtype tau (termed hTau) to mimic tau abnormality as seen in the brain of sporadic AD patients, we found that hTau accumulation activated JAK2 to phosphorylate STAT1 (Signal Transducer and Activator of Transcription 1) at Tyr701 leading to STAT1 dimerization, nuclear translocation and its activation. STAT1 activation suppressed expression of N-methyl-D-aspartate receptors (NMDARs) through direct binding to the specific GAS element of GluN1, GluN2A and GluN2B promoters, while knockdown STAT1 by AAV-Cre in STAT1flox/flox mice or expressing dominant negative Y701F-STAT1 efficiently rescued hTau-induced suppression of NMDARs expression with amelioration of synaptic functions and memory performance. These findings indicate that hTau accumulation impairs synaptic plasticity through JAK2/STAT1-induced suppression of NMDARs expression, revealing a novel mechanism for hTau-associated synapse and memory deficits.

neuroscience↗

bioRxiv2018

Smaller Hippocampal CA-1 Subfield Volume in Posttraumatic Stress Disorder

BackgroundSmaller hippocampal volume in patients with PTSD represents the most consistently reported structural alteration in the brain. Subfields of the hippocampus play distinct roles in encoding and processing of memories, which are disrupted in PTSD. We examined PTSD-associated alterations in 12 hippocampal subfields in relation to global hippocampal shape, and clinical features.\n\nMethodsCase-control cross-sectional study of US military veterans (n=282) from the Iraq and Afghanistan era were grouped into PTSD (n=142) and trauma-exposed controls (n=140). Participants underwent clinical evaluation for PTSD and associated clinical parameters followed by MRI at 3-Tesla. Segmentation with Free Surfer v6.0 produced hippocampal subfield volumes for the left and right CA1, CA3, CA4, DG, fimbria, fissure, hippocampus-amygdala transition area, molecular layer, parasubiculum, presubiculum, subiculum, and tail, as well as hippocampal meshes. Covariates included age, gender, trauma exposure, alcohol use, depressive symptoms, antidepressant medication use, total hippocampal volume, and MRI scanner model.\n\nResultsSignificantly lower subfield volumes were associated with PTSD in left CA1 (p=.01; d=.21; uncorrected), CA3 (p=.04; d=.08; uncorrected), and right CA3 (p=.02; d=.07; uncorrected) only if ipsilateral whole hippocampal volume was included as a covariate. A trend level association of L-CA1 with PTSD [F4, 221=3.32, p = 0.07] is present and the other subfield findings are non-significant if ipsilateral whole hippocampal volume is not included as a covariate. PTSD associated differences in global hippocampal shape were non-significant.\n\nConclusionsThe present finding of smaller hippocampal CA1 in PTSD is consistent with model systems in rodents that exhibit increased anxiety-like behavior from repeated exposure to acute stress. Behavioral correlations with hippocampal subfield volume differences in PTSD will elucidate their relevance to PTSD, particularly behaviors of associative fear learning, extinction training, and formation of false memories.

neuroscience↗

bioRxiv2018

PacBio library preparation using blunt-end adapter ligation produces significant artefactual fusion DNA sequences

Pacific Biosciences (PacBio) RS II sequencer, utilizing Single-Molecule, Real-Time (SMRT) technology, has revolutionized next-generation sequencing by providing an accurate long-read platform. PacBio single-molecule long reads have been used to delineate complex spliceoforms, detect mutations in highly homologous sequences, identify mRNA chimeras and chromosomal translocations, accurately haplotype phasing over multiple kilobase distances and aid in assembly of genomes with complex structural variation. The PacBio protocol for preparation of sequencing templates employs blunt-end hairpin adapter ligation, which enables a short turnaround time for sequence production. However, we have found a significant portion of sequencing yield contains chimeric reads resulting from blunt-end ligation of multiple template molecules to each other prior to adapter ligation. These artefactual fusion DNA sequences pose a major challenge to analysis and can lead to false-positive detection of fusion events. We assessed the frequency of artefactual fusion when using blunt-end adapter ligation and compared it to an alternative method using A/T overhang adapter ligation. The A/T overhang adapter ligation method showed a vast improvement in limiting artefactual fusion events and is now our recommended procedure for adapter ligation during PacBio library preparation.

genetics↗

bioRxiv2017

Optimization of Alginante- poly-L-lysine Microencapsules Strength by Box-Behnken Model for CHO Culture in Stirred Tank Bioreactor

Summary statementBox-Behnken model is an efficient method to optimized process conditions of microencapsules strength for long-term cell culture, promotes CHO cells viability and protein production in a stirred tank bioreactor.\n\nABSTRACTCell microencapsulation technology has been proved to be a valuable technology in the fields of large-scale cell culture. It is important to accurately construct the microcapsule membranes with desired properties including a certain thickness suitable for cell growth, and maximum strength for the stability of microencapsules. As single factor experiments are time-consuming to obtain the desired membrane preparation conditions, Box-Behnken model was used to investigate the interactions among reaction conditions, predict the optimized reaction conditions for given purpose, that was membrane with maximum strength and desired thickness for microencapsulated cell culture. Significant values of R2 in this study indicated the model theoretical values are very close to the measured values. Based on the desired membrane thickness, the process of maximum strength was optimized, and the prediction agreement of measured value and model theoretical value was 91.11%. The optimized microencapsules with maximum strength and 15 m membrane thickness promote CHO cells viability and protein production in stirred tank bioreactor. The result shows that Box-Behnken model is an efficient method to optimized process conditions of microencapsules strength for long-term cell culture.

bioengineering↗

bioRxiv2017

Scalable and efficient single-cell DNA methylation sequencing by combinatorial indexing.

Here we present a novel method: single-cell combinatorial indexing for methylation analysis (sci-MET), which is the first highly scalable assay for whole genome methylation profiling of single cells. We use sci-MET to produce 2,697 total single-cell bisulfite sequencing libraries and achieve read alignment rates of 69 {+/-} 7%, comparable to those of bulk cell methods. As a proof of concept, we applied sci-MET to successfully deconvolve the cellular identity of a mixture of three human cell lines.

genomics↗