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Dai, J.

Publications and source records attributed to Dai, J..

125 records · Page 7Linked to original sources

Delineating the Organization of Projection Neuron Subsets with Multi-fluorescent Rabies Virus Tracing Tool

The elegant functions of the brain are facilitated by sophisticated connections between neurons, the architecture of which is frequently characterized by one nucleus connecting to multiple targets via projection neurons. Delineating the sub-nucleus fine architecture of projection neurons in a certain nucleus could greatly facilitate its circuit, computational, and functional resolution. Here, we developed multi-fluorescent rabies virus to delineate the fine organization of corticothalamic projection neuron subsets in the primary visual cortex (V1). By simultaneously labeling multiple distinct subsets of corticothalamic projection neurons in V1 from their target nuclei in thalamus (dLGN, LP, LD), we observed that V1-dLGN corticothalamic neurons were densely concentrated in layer VI, except for several sparsely scattered neurons in layer V, while V1-LP and V1-LD corticothalamic neurons were localized to both layers V and VI. Meanwhile, we observed a fraction of V1 corticothalamic neurons targeting multiple thalamic nuclei, which was further confirmed by fMOST whole-brain imaging. We further conceptually proposed an upgraded sub-nucleus tracing system with higher throughput (21 subsets) for more complex architectural tracing. The multi-fluorescent RV tracing tool can be extensively applied to resolve architecture of projection neuron subsets, with a strong potential to delineate the computational and functional organization of these nuclei.

neuroscience↗

Single cell atlas of domestic pig brain illuminates the conservation and divergence of cell types at spatial and species levels

Domestic pig (Sus scrofa domesticus) has drawn much attention from researchers worldwide due to its implications in evolutionary biology, regenerative medicine and agriculture. The brain atlas of Homo sapiens (primate), Mus musculus (rodent), Danio rerio (fish) and Drosophila melanogaster (insect) have been constructed at single cell resolution, however, the cellular compositions of pig brain remain largely unexplored. In this study, we investigated the single-cell transcriptomic profiles of five distinct regions of domestic pig brain, from which we identified 21 clusters corresponding to six major cell types, characterized by unique spectrum of gene expression. By spatial comparison, we identified cell types enriched or depleted in certain brain regions. Inter-species comparison revealed cell-type similarities and divergences in hypothalamus between mouse and pig, providing invaluable resources for the evolutionary exploration of brain functions at single cell level. Besides, our study revealed cell types and molecular pathways closely associated with several diseases (obesity, anorexia, bulimia, epilepsy, intellectual disability, and autism spectrum disorder), bridging the gap between gene mutations and pathological phenotypes, which might be of great use to the development precise therapies against neural system disorders. Taken together, we reported, so far as we know, the first single cell brain atlas of Sus scrofa domesticus, followed by comprehensive comparisons across brain region and species, which could throw light upon future evo-devo, regenerative medicine, and agricultural studies.

bioinformatics↗

PRISM: Recovering cell type specific expression profilesfrom composite RNA-seq data

A major challenge in analyzing cancer patient transcriptomes is that the tumors are inherently heterogeneous and evolving. We analyzed 214 bulk RNA samples of a longitudinal, prospective ovarian cancer cohort and found that the sample composition changes systematically due to chemotherapy and between the anatomical sites, preventing direct comparison of treatment-naive and treated samples. To overcome this, we developed PRISM, a latent statistical framework to simultaneously extract the sample composition and cell type specific whole-transcriptome profiles adapted to each individual sample. Our results indicate that the PRISM-derived composition-free transcriptomic profiles and signatures derived from them predict the patient response better than the composite raw bulk data. We validated our findings in independent ovarian cancer and melanoma cohorts, and verified that PRISM accurately estimates the composition and cell type specific expression through whole-genome sequencing and RNA in situ hybridization experiments. PRISM is freely available with full source code and documentation.

bioinformatics↗

Accumulated degeneration of transcriptional regulation contributes to disease development and detrimental clinical outcomes of Alzheimer’s disease

Alzheimers disease (AD) is extremely complex for both causal mechanism and clinical manifestation, requiring efforts to uncover its diversity and the corresponding mechanisms. Here, we applied a modelling analysis to investigate the regulation divergence among a large-scale cohort of AD patients. We found that transcription regulation tended to get degenerated in AD patients, which contributed to disease development and the detrimental clinical outcomes, mainly by disrupting protein degradation, neuroinflammation, mitochondrial and synaptic functions. To measure the accumulated effects, we came up with a new concept, regulation loss burden, which better correlated with AD related clinical manifestations and the ageing process. The epigenetic studies to multiple active regulation marks also supported a tendency of regulation loss in AD patients. Our finding can lead to a unified model as AD causal mechanism, where AD and its diversity are contributed by accumulated degeneration of transcriptional regulation.\n\nThe significance of this study is that: (1) it is the first system biology investigation to transcription regulation divergence among AD patients; (2) we observed an accumulated degeneration of transcription regulation, which well correlates with detrimental clinical outcomes; (3) transcriptional degeneration also contributes to the ageing process, where its correlation with ages is up to 0.78.

neuroscience↗

The mitochondrial HSP90 paralog TRAP1 forms an OXPHOS-regulated tetramer and is involved in maintaining mitochondrial metabolic homeostasis

BackgroundThe molecular chaperone TRAP1, the mitochondrial isoform of cytosolic HSP90, remains poorly understood with respect to its pivotal role in the regulation of mitochondrial metabolism. Most studies have found it to be an inhibitor of mitochondrial oxidative phosphorylation (OXPHOS) and an inducer of the Warburg phenotype of cancer cells. However, others have reported the opposite and there is no consensus on the relevant TRAP1 interactors. This calls for a more comprehensive analysis of the TRAP1 interactome and of how TRAP1 and mitochondrial metabolism mutually affect each other.\n\nResultsWe show that the disruption of the gene for TRAP1 in a panel of cell lines dysregulates OXPHOS by a metabolic rewiring that induces the anaplerotic utilization of glutamine metabolism to replenish TCA cycle intermediates. Restoration of wild-type levels of OXPHOS requires full-length TRAP1. Whereas the TRAP1 ATPase activity is dispensable for this function, it modulates the interactions of TRAP1 with various mitochondrial proteins. Quantitatively by far the major interactors of TRAP1 are the mitochondrial chaperones mtHSP70 and HSP60. However, we find that the most stable stoichiometric TRAP1 complex is a TRAP1 tetramer, whose levels change in response to both a decline or an increase in OXPHOS.\n\nConclusionsOur work provides a roadmap for further investigations of how TRAP1 and its interactors such as the ATP synthase regulate cellular energy metabolism. Our results highlight that TRAP1 function in metabolism and cancer cannot be understood without a focus on TRAP1 tetramers as potentially the most relevant functional entity.

cell biology↗

The Urinary Microbiota in Relation to the Reproductive Tract Microbiota

Human urine is traditionally considered to be sterile, and whether the urine harbours distinct microbial communities has been a matter of debate. The potential link between female urine and reproductive tract microbial communities is currently not clear. Here we collected the urine samples from 147 Chinese women of reproductive age, and explored the nature of colonization by 16S rRNA gene amplicon sequencing, real-time qPCR and live bacteria culture. To demonstrate utility intra-individual Spearmans correlation was used to explore the relationship between urine and multi-sites of the reproductive tract. PERMANOVA was also performed to explore potential correlations between the lifestyle and various clinical factors and urinary bacterial communities. Our data demonstrated distinct bacterial communities in urine, indicative of a non-sterile environment. Types of diverse, Streptococcus-dominated, and Lactobacillus-dominated were the three most common types in the cohort. Detailed comparison of the urinary microbiota to the multi-sites of reproductive tract microbiota demonstrated the urinary microbiota was more similar to the microbiota in the cervix and uterine cavity instead of vagina in the same women. Our data demonstrates the potential connectivity of the microbiota in the female urogenital system and provided insight into the exploration of urethra and genital tract diseases.

microbiology↗

Identification of Host Biomarkers of EBV Latency IIb and Latency III

Deciphering the molecular pathogenesis of virally induced cancers is challenging due, in part, to the heterogeneity of both viral and host gene expression. Epstein-Barr Virus (EBV) is a ubiquitous herpesvirus prevalent in B-cell lymphomas of the immune suppressed. EBV infection of primary human B cells leads to their immortalization into lymphoblastoid cell lines (LCLs) serving as a model of these lymphomas. In previous studies, our lab has described a temporal model for immortalization with an initial phase characterized by expression of the Epstein-Barr Nuclear Antigens (EBNAs), high c-Myc activity, and hyper-proliferation in the absence of the Latent Membrane Proteins (LMPs), called latency IIb. This is followed by the long-term outgrowth of LCLs expressing the EBNAs along with the LMPs, particularly the NF{kappa}B-activating LMP1, defining latency III. LCLs, however, express a broad distribution of LMP1 such that a subset of these cells expresses LMP1 at levels seen in latency IIb, making it difficult to distinguish these two latency states. In this study, we performed mRNA-Seq on early EBV-infected latency IIb cells and latency III LCLs sorted by NF{kappa}B activity. We found that latency IIb transcriptomes clustered independently from latency III independent of NF{kappa}B. We identified and validated mRNAs defining these latency states. Indeed, we were able to distinguish latency IIb cells from LCLs expressing low levels of LMP1 using multiplex RNA-FISH targeting EBV EBNA2, LMP1, and human CCR7. This study defines latency IIb as a bona fide latency state independent from latency III and identifies biomarkers for understanding EBV-associated tumor heterogeneity.\n\nIMPORTANCEEBV is a ubiquitous pathogen with >95% of adults harboring a life-long latent infection in memory B cells. In immunocompromised individuals, latent EBV infection can result in lymphoma. The established expression profile of these lymphomas is latency III, which includes expression of all latency genes. However, single cell analysis of EBV latent gene expression in these lymphomas suggests heterogeneity where most cells express the transcription factor, EBNA2, and only a fraction express the membrane protein LMP1. Our work describes an early phase after infection where the EBNAs are expressed without LMP1, called latency IIb. However, LMP1 levels within latency III vary widely making these states hard to discriminate. This may have important implications for therapeutic responses. It is crucial to distinguish these states to understand the molecular pathogenesis of these lymphomas. Ultimately, better tools to understand the heterogeneity of these cancers will support more efficacious therapies in the future.

cancer biology↗

Meiosis related cancer-testis genes correlate with tumor aneuploidy and immune infiltration in 21 cancer types

The meiosis stage of spermatogenesis and the aneuploidy generation in tumorigenesis are highly linked. Cancer-testis genes (CT genes) were specifically expressed in testis and cancers and may serve as the molecular basis of the shared features between spermatogenesis and tumorigenesis. In the present study, we integrated multi-omics data from bulk samples and cell lines, and single cell RNA-Seq data from testis and two tumors to systematically investigate the association between CT genes and aneuploidy. After ranking genes according to their association with aneuploidy level, we found that CT genes, especially CT genes specifically expressed in meiosis, showed a consistently positive correlation with aneuploidy and homologous recombination deficiency (HRD) level. Similar results were also found in the CT non-coding genes. Then, we constructed a regulatory network based on the single cell RNA-seq data and revealed that the gain of accelerator transcriptional factors (TFs) E2F7 and E2F8 and the loss of the stabilizer TFs RFX2 and NFYA aberrantly activated CT genes in the cancers and were associated with the increase of HRD level. Finally, we found that the association between CT genes and cytotoxic infiltrating lymphocytes can be influenced by the HRD level. In sum, our results revealed the evidence of pseudomeiotic functions of CT genes in the aneuploidy generation process in the cancer cells. The results may help illuminate the origin of aneuploidy in cancers and guide future immunotherapy targeting CT antigens.

genomics↗

Evaluating brain cell marker genes based on differential gene expression and co-expression

Reliable identification of brain cell types is necessary for studying brain cell biology. Many brain cell marker genes have been proposed, but their reliability has not been fully validated. We evaluated 540 commonly-used marker genes of astrocyte, microglia, neuron, and oligodendrocyte with six transcriptome and proteome datasets from purified human and mouse brain cells (n=125). By setting new criteria of cell-specific fold change, we identified 22 gold standard marker genes (GSM) with stable cell-specific expression. Our results call into question the specificity of many proposed marker genes. We used two single-cell transcriptome datasets from human and mouse brains to explore the co-expression of marker genes (n=3337). The mouse co-expression modules were perfectly preserved in human transcriptome, but the reverse was not. Also, we proposed new criteria for identifying marker genes based on both differential expression and co-expression data. We identified 16 novel candidate marker genes (NCM) for mouse and 18 for human independently, which have the potential for use in cell sorting or other tagging techniques. We validated the specificity of GSM and NCM by in-silico deconvolution analysis. Our systematic evaluation provides a list of credible marker genes to facilitate correct cell identification, cell labeling, and cell function studies.

neuroscience↗

Geographic Patterns of Bacterioplankton among Lakes of the Middle and Lower Reaches of the Yangtze River Basin, China

In aquatic ecosystems, microbial biogeography research is critical for unveiling the mechanisms of microbial community succession. However, little is known about the microbial biogeography among interconnected lakes. To address this deficit, we used high-throughput sequencing to explore geographic patterns and the relative importance of ecological processes that shape these patterns in abundant and rare bacterial subcommunities from 25 lakes across the middle and lower reaches of Yangtze River basin (MLYB, located in southeast China), where most of the lakes are interconnected by river networks. We found that there were significant differences in both abundant and rare bacterial subcommunities between the two lake groups that were far from each other, while were no difference among the nearby lakes in each group. Both abundant and rare bacteria followed a strong distance-decay relationship, especially for rare bacteria. These findings suggest that although the interconnectivity between lakes breaks the geographical isolation of bacteria, the dispersal capability of bacterial taxa was still limited by geographic distance. We also found that although deterministic processes and stochastic processes together drive the bacterial subcommunities assembly, the stochastic processes (based on adjusted R2 in redundancy analysis) exhibited a greater influence on bacterial subcommunities. Our results implied that bacterial dispersal among interconnected lakes was more stochastically. ImportanceUnraveling the relative importance of ecological processes regulating microbial community structure is a central goal in microbial ecology. In aquatic ecosystems, microbial communities often occur in spatially structured habitats, where connectivity directly affects dispersal and metacommunity processes. Recent theoretical work suggests that directional dispersal among connected habitats leads to higher variability in local diversity and among-community composition. However, the study of microbial biogeography among natural interconnected habitats is still lacking. The findings of this study revealed interesting phenomena of microbial biogeography among natural interconnected habitats, suggested that the high interconnectivity reduced the spatial heterogeneity of bacteria, and caused the dispersal of bacteria to be more stochastically. This study has provided a deeper understanding of the biogeographic patterns of rare and abundant bacterial taxa and their determined processes among interconnected aquatic habitats.

microbiology↗

Quantum energy levels of glutamate modulate neural biophotonic signals

Glutamate is the most abundant excitatory neurotransmitter in the brain, and it plays an essential and important role in neural functions. Hypofunction of the glutamatergic pathway and the changes in the glutamate-glutamine cycle function are important neuropathological mechanisms of severe mental disorders including schizophrenia and depression. Current studies have shown that glutamate can induce neural biophotonic activity and transmission, which may involve the mechanism of photon quantum brain; however, it is unclear whether such a mechanism follows the principle of quantum mechanics. Here we show that the action of glutamate on its receptors leads to a decrease in its quantum energy levels, and glutamate then partially or completely loses its function to further induce the biophotonic activity in mouse brain slices. The reduced quantum energy levels of glutamate can be restored by direct-current electrical discharges and the use of energy transfer of chloroplast photosynthesis; hence, the quantum energy recovered glutamate can again induce significant biophotonic activity. Furthermore, the changes in quantum energy levels of glutamate are related to the exchange and transfer of electron energy on its active hydrogen atom. These findings suggest that the glutamate-induced neural biophotonic signals may be involved in the transfer of the quantum energy levels of glutamate, which implies a quantum mechanism of neurotransmitter action. The process of glutamate recycling that is related to the synergism of neurons and glial cells and certain key enzymes may be necessary for the recovery of quantum energy levels of glutamate after completion of the neural signal transmission. These findings may also provide a new idea to develop \"quantum drugs\".

neuroscience↗

Integrative analysis of Zika virus genome RNA structure reveals critical determinants of viral infectivity

Since its outbreak in 2007, Zika virus (ZIKV) has become a global health threat that causes severe neurological conditions. Here we perform a comparative in vivo structural analysis of the RNA genomes of two ZIKV strains to decipher the regulation of their infection at the RNA level. Our analysis identified both known and novel functional RNA structural elements. We discovered a functional long-range intramolecular interaction specific for the Asian epidemic strains, which contributes to their infectivity. Our findings illuminate the structural basis of ZIKV regulation and provide a rich resource for the discovery of RNA structural elements that are important for ZIKV infection.

molecular biology↗

Dissecting PCNA function with a systematically designed mutation library in yeast

Proliferating cell nuclear antigen (PCNA), encoded by POL30 in Saccharomyces cerevisiae, is a key component of DNA metabolism. Here a library consisting of 308 PCNA mutants was designed and synthesized to probe the contribution of each residue to its biological function. Five regions were identified with elevated sensitivity to DNA damaging reagents using high-throughput phenotype screening. Using a series of genetic and biochemical analyses, we demonstrated that one particular mutant, K168A, which displayed severe DNA damage sensitivity, abolished the DNA damage tolerance (DDT) pathway by disrupting interactions between PCNA and Rad5p. Subsequent domain analysis showed that the PCNA/Rad5p interaction is prerequisite for the function of Rad5p in DDT. Our study not only provides a resource in the form of a library of versatile mutants to study PCNA functions, but also reveals a key regulatory function of Rad5p, which highlights the importance of the PCNA-Rad5p interaction.\n\nAuthor summaryPCNA is regarded as the maestro of DNA replication fork because of the astonishing ability to interact with lots of partner proteins that participate in various DNA metabolism processes. However, it has remained elusive as to how does PCNA orchestrate these functions in harmony. Here, we constructed a systematic mutation library of PCNA, which covers every amino acid to map the functional sites of it. This carefully designed synthetic mutant pool could be generally useful and serve as a flexible resource, such as dissecting the functional mechanism of PCNA by genetic relationship analysis with key proteins through Synthetic genetic array. We further dissected the intrinsic mechanism for damage sensitivity of PCNAK168A, the most severe DNA damage sensitive mutant in our alanine scanning mutation library, this helps us to get better understanding of how PCNA participates in DNA damage tolerance (DDT) pathways. Our findings indicate that K168 site is vital for the interaction between DDT related partner proteins and PCNA, and also highlight the importance of the PCNA-Rad5p interaction.

genetics↗

Analysis of the role of Nidogen/entactin in basement membrane assembly and morphogenesis in Drosophila

Basement membranes (BMs) are thin sheet-like specialized extracellular matrices found at the basal surface of epithelia and endothelial tissues. They have been conserved across evolution and are required for proper tissue growth, organization, differentiation and maintenance. The major constituents of BMs are two independent networks of Laminin and Type IV Collagen interlinked by the proteoglycan Perlecan and the glycoprotein Nidogen/entactin (Ndg). The ability of Ndg to bind in vitro Collagen IV and Laminin, both with key functions during embryogenesis, anticipated an essential role for Ndg on morphogenesis linking the Laminin and Collagen IV networks. This was supported by results from in vitro and cultured embryonic tissues experiments. However, the fact that elimination of Ndg in C. elegans and mice did not affect survival, strongly questioned this proposed linking role. Here, we have isolated mutations in the only Ndg gene present in Drosophila. We find that while, similar to C.elegans and mice, Ndg is not essential for overall organogenesis or viability, it is required for appropriate fertility. We also find, alike in mice, tissue-specific requirements of Ndg for proper assembly and maintenance of certain BMs, namely those of the adipose tissue and flight muscles. In addition, we have performed a thorough functional analysis of the different Ndg domains in vivo. Our results support an essential requirement of the G3 domain for Ndg function and unravel a new key role for the Rod domain in regulating Ndg incorporation into BMs. Furthermore, uncoupling of the Laminin and Collagen IV networks is clearly observed in the larval adipose tissue in the absence of Ndg, indeed supporting a linking role. In light of our findings, we propose that BM assembly and/or maintenance is tissue-specific, which could explain the diverse requirements of a ubiquitous conserved BM component like Nidogen.\n\nAuthor SummaryBasement membranes (BMs) are thin layers of specialized extracellular matrices present in every tissue of the human body. Its main constituents are two networks of Laminin and Type IV Collagen linked by Nidogen (Ndg) and proteoglycans. They form an organized scaffold that regulates organ morphogenesis and function. Mutations affecting BM components are associated with organ dysfunction and several congenital diseases. Thus, a better comprehension of BM assembly and maintenance will not only help to learn more about organogenesis but also to a better understanding and, hopefully, treatment of these diseases. Here, we have used Drosophila to analyse the role of Ndg in BM formation in vivo. Elimination of Ndg in worms and mice does not affect survival, strongly questioning its proposed linking role, derived from in vitro experiments. Here, we show that in the fly Ndg is dispensable for BM assembly and preservation in many tissues, but absolutely required in others. Furthermore, our functional study of the different Ndg domains challenges the significance of some interactions between BM components derived from in vitro experiments, while confirming others, and reveals a new key requirement for the Rod domain in Ndg function and incorporation into BMs.

developmental biology↗

Understanding the limit of open search in the identification of peptides with post-translational modifications -- A simulation-based study

MotivationAnalyzing tandem mass spectrometry data to recognize peptides in a sample is the fundamental task in computational proteomics. Traditional peptide identification algorithms perform well when identifying unmodified peptides. However, when peptides have post-translational modifications (PTMs), these methods cannot provide satisfactory results. Recently, Chick et al., 2015 and Yu et al., 2016 proposed the spectrum-based and tag-based open search methods, respectively, to identify peptides with PTMs. While the performance of these two methods is promising, the identification results vary greatly with respect to the quality of tandem mass spectra and the number of PTMs in peptides. This motivates us to systematically study the relationship between the performance of open search methods and quality parameters of tandem mass spectrum data, as well as the number of PTMs in peptides.\n\nResultsThrough large-scale simulations, we obtain the performance trend when simulated tandem mass spectra are of different quality. We propose an analytical model to describe the relationship between the probability of obtaining correct identifications and the spectrum quality as well as the number of PTMs. Based on the analytical model, we can quantitatively describe the necessary condition to effectively apply open search methods.\n\nAvailabilitySource codes of the simulation are available at http://bioinformatics.ust.hk/PST.html.\n\nContactboningli@ust.hk or eeyu@ust.hk\n\nSupplementary informationSupplementary data are available at Bioinformatics online.

bioinformatics↗

Xolik: finding cross-linked peptides with maximum paired scores in linear time

MotivationCross-linking technique coupled with mass spectrometry (MS) is widely used in the analysis of protein structures and protein-protein interactions. In order to identify cross-linked peptides from MS data, we need to consider all pairwise combinations of peptides, which is computationally prohibitive when the sequence database is large. To alleviate this problem, some heuristic screening strategies are used to reduce the number of peptide pairs during the identification. However, heuristic screening criteria may ignore true findings.\n\nResultsWe directly tackle the combination challenge without using any screening strategies. With the additive scoring function and the data structure of double-ended queue, the proposed algorithm reduces the quadratic time complexity of exhaustive searching down to the linear time complexity. We implement the algorithm in a tool named Xolik, and the running time of Xolik is validated using databases with different number of proteins. Experiments using synthetic and empirical datasets show that Xolik outperforms existing tools in terms of running time and statistical power.\n\nAvailabilitySource code and binaries of Xolik are freely available at http://bioinformatics.ust.hk/Xolik.html.\n\nContacteeyu@ust.hk\n\nSupplementary informationSupplementary data are available at Bioinformatics online.

bioinformatics↗

Intracellular BH3 profiling reveals shifts in anti-apoptotic dependency in B-cell maturation and activation

Apoptosis is critical to B-cell maturation, but studies of apoptotic regulation in primary human B cells is lacking. Previously, we found that infecting human B cells with Epstein-Barr virus induces two different survival strategies (Price et al., 2017). Here, we sought to better understand the mechanisms of apoptotic regulation in normal and activated B cells. Using intracellular BH3 profiling (iBH3), we defined the Bcl2-dependency of B-cell subsets from human peripheral blood and tonsillar lymphoid tissue as well as mitogen-activated B cells. We found that naive and memory B cells were BCL-2 dependent, while germinal center B cells were MCL-1 dependent and plasma cells were BCL-XL dependent. Proliferating B cells activated by CpG or CD40L/IL-4 became more dependent upon MCL-1 and BCL-XL. As B-cell lymphomas often rely on survival mechanisms derived from normal and activated B cells, these findings offer new insight into potential therapeutic strategies for lymphomas.

immunology↗