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Zhang, F.

Publications and source records attributed to Zhang, F..

At least 451 records · Page 25Linked to original sources

Conserved allosteric pathways for activation of TRPV3 revealed through engineering vanilloid-sensitivity

The Transient Receptor Potential Vanilloid 1 (TRPV) channel is activated by an array of stimuli, including heat and vanilloid compounds. The TRPV1 homologues TRPV2 and TRPV3 are also activated by heat, but sensitivity to vanilloids and many other agonists is not conserved among TRPV subfamily members. It was recently discovered that four mutations in TRPV2 are sufficient to render the channel sensitive to the TRPV1-specific vanilloid agonist resiniferatoxin (RTx). Here we show that mutation of six residues in TRPV3 corresponding to the vanilloid site in TRPV1 is sufficient to engineer RTx binding. However, robust activation of TRPV3 by RTx requires facilitation of channel opening by introducing individual mutations in the pore, temperatures > 30{degrees}C, or co-stimulation with another agonist. Our results demonstrate that the energetics of channel activation can determine the apparent sensitivity to a stimulus and suggest that allosteric pathways for activation are conserved in the TRPV family.

neuroscience↗

Bacterial strain displacement in inflammatory bowel diseases after fecal microbiota transplantation

Fecal microbiota transplantation (FMT), which is thought to have the potential to correct dysbiosis of gut microbiota, has recently been used to treat inflammatory bowel disease (IBD). To elucidate the extent and principles of microbiota engraftment in IBD patients after FMT treatment, we conducted an interventional prospective cohort study. The cohort included two categories of patients: (1) patients with moderate to severe Crohns disease (CD) (Harvey-Bradshaw Index [≥] 7, n = 11, and (2) patients with ulcerative colitis (UC) (Montreal classification, S2 and S3, n = 4). All patients were treated with a single FMT (via mid-gut, from healthy donors) and follow-up visits were performed at baseline, 3 days, one week, and one month after FMT (missing time points included). At each follow-up time point, fecal samples of the participants were collected along with their clinical metadata. For comparative analysis, 10 fecal samples from 10 healthy people were included to represent the diversity level of normal gut microbiota. Additionally, the metagenomic data of 25 fecal samples from 5 individuals with metabolic syndrome who underwent autologous FMT treatment were downloaded from a previous published paper to represent natural microbiota shifts during FMT. All fecal samples underwent shotgun metagenomic sequencing. We found that 3 days after FMT, 11 out of 15 recipients were in remission (3 out of 4 UC recipients; 8 out of 11 CD recipients). Generally, bacterial colonization was observed to be lower in CD recipients than in UC recipients at both species and strain levels. Furthermore, across species, different strains displayed disease-specific displacement advantages under two-disease status. Finally, most post-FMT species (> 80%) could be properly predicted (AUC > 85%) using a random forest classification model, with the gut microbiota composition and clinical parameters of pre-FMT recipients acting as the most contributive factors for prediction accuracy.

clinical trials↗

Intensive and Specific Feedback Self-control of MicroRNA Targeting Activity

The miRNA pathway consists of three segments - biogenesis, targeting and downstream regulatory effectors. How the cells control their activities remains incompletely understood. This study explored the intrinsically complex miRNA-mRNA targeting relationships, and suggested differential mechanistic control of the three segments. We first analyzed evolutionarily conserved sites for conserved miRNAs in the human transcriptome. Strikingly, AGO1, AGO2 and AGO3 are all among the top 14 mRNAs with highest numbers of unique conserved miRNA sites, and so is ANKRD52, the phosphatase regulatory subunit of the recently identified AGO phosphorylation cycle (AGOs, CSNK1A1, ANKRD52 and PPP6C). The mRNAs for TNRC6, which acts together with loaded AGO to channel miRNA-mediated regulation actions onto specific mRNAs, are also heavily miRNA-targeted. Moreover, mRNAs of the AGO phosphorylation cycle share much more than expected miRNA binding sites. In contrast, upstream miRNA biogenesis mRNAs do not display these characteristics, and neither do the downstream regulatory effector mRNAs. In a word, miRNAs heavily and directly feedback-regulate their targeting machinery mRNAs, but neither upstream biogenesis nor downstream regulatory effector mRNAs. The observation was then confirmed with experimentally determined miRNA-mRNA target relationships. In summary, our exploration of the miRNA-mRNA target relationship uncovers intensive, and specific, feedback auto-regulation of miRNA targeting activity directly by miRNAs themselves, i.e., segment-specific feedback auto-regulation of miRNA pathway. Our results also suggest that the complexity of miRNA-mRNA targeting relationship - a defining feature of miRNA biology - should be a rich source for further functional exploration.

cell biology↗

Effect of Platelet-activating factor on barrier function of ARPE-19 cells

PURPOSETo examine the effects of platelet-activating factor (PAF) on tight junction permeability in cultured retinal pigment epithelial (RPE) cells.\n\nMETHODSA human RPE cell line (ARPE-19) cultured on microporous filter supports was used. PAF and WEB2086, which is a specific PAF-receptor (PAF-R) antagonist, were added to the culture medium. RPE monolayer permeability was measured using transepithelial electrical resistance (TER) and sodium fluorescein flux. The expression of the tight junction protein zonula occludens (ZO)-1 was assessed using immunohistochemistry. We also measured the vascular endothelial growth factor (VEGF) level in cultures treated with PAF, and RPE monolayer permeability was measured again in the presence of neutralizing antibodies to VEGF.\n\nRESULTSPAF significantly decreased the TER of the RPE monolayer and enhanced sodium fluorescein flux. ZO-1 expression was downregulated in PAF-supplemented medium. These effects were abolished with PAF-R blockage. PAF stimulation increased VEGF expression in RPE cells, and neutralization of VEGF with antibodies caused partial recovery of barrier properties.\n\nCONCLUSIONSThe tight junctions of ARPE-19 cells are altered by PAF, and these effects are partly mediated by the upregulation of VEGF expression in these cells. Our results contribute to growing evidence supporting the role of PAF in choroidal neovascularization, and our findings suggest that PAF is a novel therapeutic target for increased permeability of the RPE monolayer.

cell biology↗

Transcriptional regulation of voltage-gated sodium channels contributes to GM-CSF induced pain

Granolocyte-macrophage colony stimulating factor (GM-CSF) induces production of granulocyte and macrophage populations from the hematopoietic progenitor cells; it is one of the most common growth factors in the blood. GM-CSF is also involved in bone cancer pain development by regulating tumor-nerve interactions, remodeling of peripheral nerves and sensitization of damage-sensing (nociceptive) nerves. However, the precise mechanism for GM-CSF-dependent pain is unclear. In this study, we found that GM-CSF is highly expressed in human malignant osteosarcoma. Rats implanted with bone cancer cells develop mechanical and thermal hyperalgesia but antagonizing GM-CSF in these animals significantly reduced such hypersensitivity. Nociceptor-specific voltage gated Na+ channels Nav1.7, Nav1.8 and Nav1.9 were found to be selectively up-regulated in rat DRG neurons treated with GM-CSF, which resulted in enhanced excitability. GM-CSF activated the Jak2 and Stat3 signaling pathway which promoted the transcription of Nav1.7-1.9 in DRG neurons. Accordingly targeted knocking down either Nav1.7-1.9 or Jak2/Stat3 in DRG neurons alleviated the hyperalgesia in rats. Our findings describe a new bone cancer pain mechanism and provide a new insight into the physiological and pathological functions of GM-CSF.

neuroscience↗

Pooled optical screens in human cells

Large-scale genetic screens play a key role in the systematic discovery of genes underlying cellular phenotypes. Pooling of genetic perturbations greatly increases screening throughput, but has so far been limited to screens of enrichments defined by cell fitness and flow cytometry, or to comparatively low-throughput single cell gene expression profiles. Although microscopy is a rich source of spatial and temporal information about mammalian cells, high-content imaging screens have been restricted to much less efficient arrayed formats. Here, we introduce an optical method to link perturbations and their phenotypic outcomes at the singlecell level in a pooled setting. Barcoded perturbations are read out by targeted in situ sequencing following image-based phenotyping. We apply this technology to screen a focused set of 952 genes across >3 million cells for involvement in NF-{kappa}B activation by imaging the translocation of RelA (p65) to the nucleus, recovering 20 known pathway components and 3 novel candidate positive regulators of IL-1{beta} and TNF-stimulated immune responses.

genomics↗

Defining Inflammatory Cell States in Rheumatoid Arthritis Joint Synovial Tissues by Integrating Single-cell Transcriptomics and Mass Cytometry

To define the cell populations in rheumatoid arthritis (RA) driving joint inflammation, we applied single-cell RNA-seq (scRNA-seq), mass cytometry, bulk RNA-seq, and flow cytometry to sorted T cells, B cells, monocytes, and fibroblasts from 51 synovial tissue RA and osteoarthritis (OA) patient samples. Utilizing an integrated computational strategy based on canonical correlation analysis to 5,452 scRNA-seq profiles, we identified 18 unique cell populations. Combining mass cytometry and transcriptomics together revealed cell states expanded in RA synovia: THY1+HLAhigh sublining fibroblasts (OR=33.8), IL1B+ pro-inflammatory monocytes (OR=7.8), CD11c+T-bet+ autoimmune-associated B cells (OR=5.7), and PD-1+Tph/Tfh (OR=3.0). We also defined CD8+ T cell subsets characterized by GZMK+, GZMB+, and GNLY+ expression. Using bulk and single-cell data, we mapped inflammatory mediators to source cell populations, for example attributing IL6 production to THY1+HLAhigh fibroblasts and naive B cells, and IL1B to pro-inflammatory monocytes. These populations are potentially key mediators of RA pathogenesis.

immunology↗

Regulatory B cells contribute to the alleviation of colitis induced by Dextran Sulphate Sodium after H.pylori infection

BackgroundEpidemiological studies showed that there was an inverse relationship between Helicobacter pylori infection and the incidence of inflammatory bowel disease. Our previous research indicated that the regulatory immune responses induced by H.pylori infection were not limited to gastric mucosa, and the balance of intestinal mucosal immunity was influenced. In this study, we investigated the role of the regulatory B cells in the effects of the H.pylori infection on acute and chronic colitis induced by dextran sulphate sodium.\n\nMethodsMice were infected with H.pylori and then colitis was induced by 3% DSS, the CD19+IL-10+Breg cells and CD4+CD25+Foxp3+Treg cells in blood spleen mesenteric lymph nodes (MLN) Peyers Patches (PP) and gastrointestinal mucosa were measured and examined. The anti- and pro-inflammatory cytokines were also detected at mRNA level.\n\nResultsIn the acute and chronic colitis groups, DAI and colonic histological scores reduced significantly and colon length shorted less; the anti-inflammatory cytokines mRNA expression upregulated while the pro-inflammatory cytokines mRNA expression downregulated in colonic mucosa; and the percentages of CD19+IL-10+Breg cells in blood spleen MLN PP were higher in the H.pylori/DSS co-treated group compared with the DSS treated group.\n\nConclusionH.pylori infection can alleviate the acute and chronic colitis induced by DSS. CD19+IL-10+Breg cells may play a critical role in the alleviation of acute and chronic colitis following H.pylori infection.

immunology↗

Condition-adaptive fused graphical lasso (CFGL): an adaptive procedure for inferring condition-specific gene co-expression network

Co-expression network analysis provides useful information for studying gene regulation in biological processes. Examining condition-specific patterns of co-expression can provide insights into the underlying cellular processes activated in a particular condition. One challenge in this type of analysis is that the sample sizes in each condition are usually small, making the statistical inference of co-expression patterns highly underpowered. A joint network construction that borrows information from related structures across conditions has the potential to improve the power of the analysis.\n\nOne possible approach to constructing the co-expression network is to use the Gaussian graphical model. Though several methods are available for joint estimation of multiple graphical models, they do not fully account for the heterogeneity between samples and between co-expression patterns introduced by condition specificity. Here we develop the condition-adaptive fused graphical lasso (CFGL), a data-driven approach to incorporate condition specificity in the estimation of co-expression networks. We show that this method improves the accuracy with which networks are learned. The application of this method on a rat multi-tissue dataset and The Cancer Genome Atlas (TCGA) breast cancer dataset provides interesting biological insights. In both analyses, we identify numerous modules enriched for Gene Ontology functions and observe that the modules that are upregulated in a particular condition are often involved in condition-specific activities. Interestingly, we observe that the genes strongly associated with survival time in the TCGA dataset are less likely to be network hubs, suggesting that genes associated with cancer progression are likely to govern specific functions, rather than regulating a large number of biological processes. Additionally, we observed that the tumor-specific hub genes tend to have few shared edges with normal tissue, revealing tumor-specific regulatory mechanism.\n\nAuthor summaryGene co-expression networks provide insights into the mechanism of cellular activity and gene regulation. Condition-specific mechanisms may be identified by constructing and comparing co-expression networks of multiple conditions. We propose a novel statistical method to jointly construct co-expression networks for gene expression profiles from multiple conditions. By using a data-driven approach to capture condition-specific co-expression patterns, this method is effective in identifying both co-expression patterns that are specific to a condition and that are common across conditions. The application of this method on real datasets reveals interesting biological insights.

bioinformatics↗

Novel susceptibility loci and genetic regulation mechanisms for type 2 diabetes

We conducted a meta-analysis of genome-wide association studies (GWAS) with [~]16 million genotyped/imputed genetic variants in 62,892 type 2 diabetes (T2D) cases and 596,424 controls of European ancestry. We identified 139 common and 4 rare (minor allele frequency < 0.01) variants associated with T2D, 42 of which (39 common and 3 rare variants) were independent of the known variants. Integration of the gene expression data from blood (n = 14,115 and 2,765) and other T2D-relevant tissues (n = up to 385) with the GWAS results identified 33 putative functional genes for T2D, three of which were targeted by approved drugs. A further integration of DNA methylation (n = 1,980) and epigenomic annotations data highlighted three putative T2D genes (CAMK1D, TP53INP1 and ATP5G1) with plausible regulatory mechanisms whereby a genetic variant exerts an effect on T2D through epigenetic regulation of gene expression. We further found evidence that the T2D-associated loci have been under purifying selection.

genetics↗

Immuno-genomic PanCancer Landscape Reveals Diverse Immune Escape Mechanisms and Immuno-Editing Histories

Immune reactions in the tumor micro-environment are one of the cancer hallmarks and emerging immune therapies have been proven effective in many types of cancer. To investigate cancer genome-immune interactions and the role of immuno-editing or immune escape mechanisms in cancer development, we analyzed 2,834 whole genomes and RNA-seq datasets across 31 distinct tumor types from the PanCancer Analysis of Whole Genomes (PCAWG) project with respect to key immuno-genomic aspects. We show that selective copy number changes in immune-related genes could contribute to immune escape. Furthermore, we developed an index of the immuno-editing history of each tumor sample based on the information of mutations in exonic regions and pseudogenes. Our immuno-genomic analyses of pan-cancer analyses have the potential to identify a subset of tumors with immunogenicity and diverse background or intrinsic pathways associated with their immune status and immuno-editing history.

genomics↗

Identifying gene targets for brain-related traits using transcriptomic and methylomic data from blood

Understanding the difference in genetic regulation of gene expression between brain and blood is important for discovering genes associated with brain-related traits and disorders. Here, we estimate the correlation of genetic effects at the top associated cis-expression (cis-eQTLs or cis-mQTLs) between brain and blood for genes expressed (or CpG sites methylated) in both tissues, while accounting for errors in their estimated effects (rb). Using publicly available data (n = 72 to l,366), we find that the genetic effects of cis-eQTLs (PeQTL < 5x10-8) or mQTLs (PmQTL < 1x10-10) are highly correlated between independent brain and blood samples ([Formula] with SE = 0.015 for cis-eQTL and [Formula] with SE = 0.006 for cis-mQTLs). Using meta-analyzed brain eQTL/mQTL data (n = 526 to 1,194), we identify 61 genes and 167 DNA methylation (DNAm) sites associated with 4 brain-related traits and disorders. Most of these associations are a subset of the discoveries (97 genes and 295 DNAm sites) using data from blood with larger sample sizes (n = l,980 to 14,115). We further find that cis-eQTLs with tissue-specific effects are approximately uniformly distributed across all the functional annotation categories, and that mean difference in gene expression level between brain and blood is almost independent of the difference in the corresponding cis-eQTL effect. Our results demonstrate the gain of power in gene discovery for brain-related phenotypes using blood cis-eQTL or cis-mQTL data with large sample sizes.

genetics↗

Within-host recombination in structural proteins of the Foot-and-Mouth Disease Virus

Although recombination is known to occur in FMDV, it is considered only a minor determinant of virus sequence diversity. This is because recombination appears to be highly suppressed at phylogenetic scales; inter-serotypic recombination events are rare; and in those a mosaic structure is present whereby recombination only occurs almost exclusively in non-structural proteins. Here we show that co-inoculation of closely related strains in buffaloes results over time in extensive within-host recombination in the genomic region coding for structural proteins. This enables us to directly estimate recombination rates for the first time. Quite surprisingly, the effective recombination rate in VP1 during the acute infection phase turns out to be about 0.1 per base per year, i.e. comparable to the mutation/substitution rate. Thanks to the features of our experimental setup, we are also able to build a high-resolution map of effective within-host recombination in the capsid-coding region. We find that the linkage disequilibrium pattern inside VP1 points to a mosaic structure with two main genetic blocks. Positive epistatic interactions between co-evolved variants appear to be present both within and between blocks. These interactions are due to intra-host selection both at the RNA and protein level. Overall our findings show that during FMDV co-infections by closely related strains, capsid-coding genes recombine within the host at a much higher rate than expected, despite the presence of strong constraints dictated by the capsid structure. Although those intra-host results are not immediately transportable to a phylogenetic setting, they force us to reconsider the relevance of recombination and epistasis, suggesting that they must play a major and so far underappreciated role in the molecular evolution of the virus at all time scales.\n\nAuthor summaryRecombination in the capsid-coding region of the Foot-and-Mouth Disease virus genome is highly suppressed at phylogenetic scales. However, the role of recombination in the intra-host dynamics of the virus is not known. In our experiment, a co-infection of African buffaloes with closely related FMDV strains results in a population structure of the intra-host viral swarm, allowing us to detect recombination events. For structural protein-coding sequences, the swarm dynamics is driven by extensive within-host recombination. During the acute infection phase, we infer intra-host recombination rates of 0.1 per base per year, comparable to the typical mutation rate of the virus. The recombination map reveals two linkage blocks within the VP1 protein-coding sequence. Epistatic interactions between co-evolved mutations in VP1 are caused by intra-host selection at the RNA and protein level and are present both within and between blocks. Our findings support a major role for recombination and epistasis in the intra-host evolution of FMDV.

microbiology↗

Genome-wide study identifies 611 loci associated with risk tolerance and risky behaviors

Humans vary substantially in their willingness to take risks. In a combined sample of over one million individuals, we conducted genome-wide association studies (GWAS) of general risk tolerance, adventurousness, and risky behaviors in the driving, drinking, smoking, and sexual domains. We identified 611 approximately independent genetic loci associated with at least one of our phenotypes, including 124 with general risk tolerance. We report evidence of substantial shared genetic influences across general risk tolerance and risky behaviors: 72 of the 124 general risk tolerance loci contain a lead SNP for at least one of our other GWAS, and general risk tolerance is moderately to strongly genetically correlated ([Formula] to 0.50) with a range of risky behaviors. Bioinformatics analyses imply that genes near general-risk-tolerance-associated SNPs are highly expressed in brain tissues and point to a role for glutamatergic and GABAergic neurotransmission. We find no evidence of enrichment for genes previously hypothesized to relate to risk tolerance.

genetics↗

Reversing Glial Scar Back To Neural Tissue Through NeuroD1-Mediated Astrocyte-To-Neuron Conversion

Nerve injury often causes neuronal loss and glial proliferation, disrupting the delicate balance between neurons and glial cells in the brain. Recently, we have developed an innovative technology to convert internal reactive glial cells into functional neurons inside the mouse brain. Here, we further demonstrate that such glia-to-neuron conversion can rebalance neuron-glia ratio and reverse glial scar back to neural tissue. Specifically, using a severe stab injury model in the mouse cortex, we demonstrated that ectopic expression of NeuroD1 in reactive astrocytes significantly reduced glial reactivity and transformed toxic A1 astrocytes into less harmful astrocytes before neuronal conversion. Importantly, astrocytes were not depleted after neuronal conversion but rather repopulated due to its intrinsic proliferation capability. Remarkably, converting reactive astrocytes into neurons also significantly reduced microglia-mediated neuroinflammation. Moreover, accompanying regeneration of new neurons together with repopulation of new astrocytes, blood-brain-barrier was restored and synaptic density was rescued in the injury sites. Together, these results demonstrate that glial scar can be reversed back to neural tissue through rebalancing neuron:glia ratio after glia-to-neuron conversion.

neuroscience↗

Early candidate urine biomarkers for detecting Alzheimer’s disease before beta amyloid plaque deposition in an APP (swe)/PSEN1dE9 transgenic mouse model

Alzheimers disease (AD) is an incurable age-associated neurodegenerative disorder that is characterized by irreversible progressive cognitive deficits and extensive brain damage. The identification of candidate biomarkers before beta amyloid plaque deposition occurs is therefore of great importance for the early intervention of AD. Urine, which is not regulated by homeostatic mechanisms, theoretically accumulates changes associated with AD earlier than cerebrospinal fluid and blood. In this study, an APP (swe)/PSEN1dE9 transgenic mouse model was used to identify candidate biomarkers for early AD. Urine samples were collected from 4-, 6-, and 8-month-old transgenic mouse models, and the urinary proteomes were profiled using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The levels of 33 proteins differed significantly between wild-type and 4-month-old mice, which had not started to deposit beta amyloid plaque. Among these proteins, 16 have been associated with the mechanisms of AD, while 9 have been suggested as AD biomarkers. Our results indicated that urine proteins enable detecting AD before beta amyloid plaque deposition, which may present an opportunity for intervention.

molecular biology↗

Phytophthora methylomes modulated by expanded 6mA methyltransferases are associated with adaptive genome regions

Filamentous plant pathogen genomes often display a bipartite architecture with gene sparse, repeat-rich compartments serving as a cradle for adaptive evolution. However, the extent to which this \"two-speed\" genome architecture is associated with genome-wide epigenetic modifications is unknown. Here, we show that the oomycete plant pathogens Phytophthora infestans and Phytophthora sojae possess functional adenine N6- methylation (6mA) methyltransferases that modulate patterns of 6mA marks across the genome. In contrast, 5-methylcytosine (5mC) could not be detected in the two Phytophthora species. Methylated DNA IP Sequencing (MeDIP-seq) of each species revealed that 6mA is depleted around the transcriptional starting sites (TSS) and is associated with low expressed genes, particularly transposable elements. Remarkably, genes occupying the gene-sparse regions have higher levels of 6mA compared to the remainder of both genomes, possibly implicating the methylome in adaptive evolution of Phytophthora. Among three putative adenine methyltransferases, DAMT1 and DAMT3 displayed robust enzymatic activities. Surprisingly, single knockouts of each of the 6mA methyltransferases in P. sojae significantly reduced in vivo 6mA levels, indicating that the three enzymes are not fully redundant. MeDIP-seq of the damt3 mutant revealed uneven patterns of 6mA methylation across genes, suggesting that PsDAMT3 may have a preference for gene body methylation after the TSS. Our findings provide evidence that 6mA modification is an epigenetic mark of Phytophthora genomes and that complex patterns of 6mA methylation by the expanded 6mA methyltransferases may be associated with adaptive evolution in these important plant pathogens.

molecular biology↗

Effects of regional differences on the urinary proteomes of healthy Chinese individuals

Urine is a promising biomarker source for clinical proteomics studies. Although regional physiological differences are common in multi-center clinical studies, the presence of significant differences in the urinary proteomes of individuals from different regions remains unknown. In this study, morning urine samples were collected from healthy urban residents in three regions of China and urinary proteins were preserved using a membrane-based method (Urimem). The urine proteomes of 27 normal samples were analyzed using LC-MS/MS and compared among the three regions. We identified 1,898 proteins from Urimem samples using label-free proteome quantification, of which 62 urine proteins were differentially expressed among the three regions. Hierarchical clustering analysis showed that inter-regional differences caused less significant changes in the urine proteome than inter-sex differences. Of the 62 differentially expressed proteins, 10 have been reported to be disease biomarkers in previous clinical studies. Urimem facilitates urinary protein storage for large-scale urine sample collection, and thus accelerates biobank development and urine biomarker studies employing proteomics approaches. Regional differences are a confounding factor influencing the urine proteome and should be considered in future multi-center biomarker studies.

physiology↗