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Lee, C.-Y.

Publications and source records attributed to Lee, C.-Y..

51 records · Page 3Linked to original sources

Predicting activatory and inhibitory drug-target interactions based on mol2vec and genetically perturbed transcriptomes

A computational approach to identifying drug-target interactions (DTIs) is a credible strategy for accelerating drug development and understanding the mechanisms of action of small molecules. However, current methods are limited to providing simple DTIs without mode of action (MoA), or they show unsatisfactory performance for a limited range of compounds and targets. Here, we propose AI-DTI, a novel method that predicts activatory and inhibitory DTIs by combining the mol2vec and genetically perturbed transcriptomes. We trained the model on large-scale DTIs with MoA and found that our model outperformed a previous model that predicted activatory and inhibitory DTIs. To extend the applicability, we applied the inferential method for the target vector so that our method can learn and predict a wider range of targets. Our method achieved satisfactory performance in an independent dataset where the target was unseen in the training set and a high-throughput screening dataset where positive and negative samples were explicitly defined. Finally, our method successfully rediscovered approximately half of the DTIs for drugs used in the treatment of COVID-19. These results indicate that AI-DTI is a practically useful tool for guiding drug discovery processes and generating plausible hypotheses that can reveal unknown mechanisms of drug action.

bioinformatics↗

Cell-type-specific chromatin occupancy by the pioneer factor Zelda drives key developmental transitions in Drosophila

During Drosophila embryogenesis, the essential pioneer factor Zelda defines hundreds of cis-regulatory regions and in doing so reprograms the zygotic transcriptome. While Zelda is essential later in development, it is unclear how the ability of Zelda to define cis-regulatory regions is shaped by cell-type-specific chromatin architecture. Asymmetric division of neural stem cells (neuroblasts) in the fly brain provide an excellent paradigm for investigating the cell-type-specific functions of this pioneer factor. We show that Zelda synergistically functions with Notch to maintain neuroblasts in an undifferentiated state. Zelda misexpression reprograms progenitor cells to neuroblasts, but this capacity is limited by transcriptional repressors critical for progenitor commitment. Zelda genomic occupancy in neuroblasts is reorganized as compared to the embryo, and this reorganization is driven by differences in chromatin accessibility and cofactor availability. We propose that Zelda regulates essential transitions in the neuroblasts and embryo through a shared gene-regulatory network by defining cell-type-specific enhancers.

developmental biology↗

FILER: large-scale, harmonized FunctIonaL gEnomics Repository

MotivationQuerying massive collections of functional genomic and annotation data, linking and summarizing the query results across data sources and data types are important steps in high-throughput genomic and genetic analytical workflows. However, accomplishing these steps is difficult because of the heterogeneity and breadth of data sources, experimental assays, biological conditions (e.g., tissues, cell types), data types, and file formats. ResultsFunctIonaL gEnomics Repository (FILER) is a large-scale, harmonized functional genomics data catalog uniquely providing: 1) streamlined access to >50,000 harmonized, annotated functional genomic and annotation datasets across >20 integrated data sources, >1,100 biological conditions/tissues/cell types, and >20 experimental assays; 2) a scalable, indexing-based genomic querying interface; 3) ability for users to analyze and annotate their own experimental data against reference datasets. This rich resource spans >17 Billion genomic records for both GRCh37/hg19 and GRCh38/hg38 genome builds. FILER scales well with the experimental (query) data size and the number of reference datasets and data sources. When evaluated on large-scale analysis tasks, FILER demonstrated great efficiency as the observed running time for querying 1000x more genomic intervals (106 vs. 103) against all 7x109 hg19 FILER records increased sub-linearly by only a factor of 15x. Together, these features facilitate reproducible research and streamline querying, integrating, and utilizing large-scale functional genomics and annotation data. Availability and implementationFILER can be 1) freely accessed at https://lisanwanglab.org/FILER, 2) deployed on cloud or local servers (https://bitbucket.org/wanglab-upenn/FILER), and 3) integrated with other pipelines using provided scripts. Contactlswang@pennmedicine.upenn.edu

bioinformatics↗

Structure-based functional study of a peptide of an ecdysozoan superfamily: reveling a common molecular architecture and receptor-interacting residues

A neuropeptide (Sco-CHH-L), belonging to the crustacean hyperglycemic hormone (CHH) superfamily and preferentially expressed in the pericardial organs (POs) of the mud crab Scylla olivacea, was functionally and structurally studied. Its expression levels were significantly higher than the alternative splice form (Sco-CHH) in the POs and increased significantly after animals were subjected to a hypo-osmotic stress. Sco-CHH-L, but not Sco-CHH, significantly stimulated in vitro the Na+, K+-ATPase activity in the posterior (6th) gills. Furthermore, solution structure of Sco-CHH-L was resolved using nuclear magnetic resonance spectroscopy revealing that it has an N-terminal tail, three -helices (2, Gly9-Asn28; 3, His34-Gly38; 5, Glu62-Arg72), and a {pi}-helix ({pi}4, Cys43-Tyr53) and is structurally constrained by a pattern of disulfide bonds (Cys7-Cys43, Cys23-Cys39, Cys26-Cys52), which is characteristic of the CHH superfamily-peptides. Sco-CHH-L is topologically most similar to the molt-inhibiting hormone from the Kuruma prawn Marsupenaeus japonicus with a backbone root-mean-square-deviation of 3.12 [A]. Ten residues of Sco-CHH-L were chosen for alanine-substituted and the resulting mutants were functionally tested using the gill Na+, K+-ATPase activity assay, showing that the functionally important residues (I2, F3, E45, D69, I71, G73) are located at either end of the sequence, which are sterically close to each other and presumably constitutes the receptor binding sites. Sco-CHH-L was compared with other members of the superfamily revealing a molecular architecture, which is suggested to be common for the crustacean members of the superfamily, with the properties of the residues constituting the presumed receptor binding sites being the major factors dictating the ligand-receptor binding specificity.

biochemistry↗

Cullin3 promotes stem cell progeny differentiation by facilitating aPKC-directed asymmetric Numb localization

Asymmetric segregation of Numb is a conserved mechanism for regulating Notch-mediated binary cell fate decisions; however, the mechanisms controlling Numb segregation remain unclear. Previous studies have proposed an "exclusion" model, suggesting that atypical protein kinase C (aPKC) negatively regulates Numb cortical localization. Here, we report that aPKC kinase activity positively promotes basal cortical Numb localization during asymmetric division of Drosophila neural stem cells (neuroblasts) and that Cullin 3 (Cul3) is required for aPKC-directed basal Numb localization. In numb- or cul3-mutant brains, decreased levels of Numb segregated into neuroblast progeny failed to downregulate Notch, leading to supernumerary neuroblast formation. Increased aPKC kinase activity suppressed supernumerary neuroblast formation by concentrating residual Numb protein at the basal cortex and in neuroblast progeny, whereas decreased aPKC function enhanced the supernumerary neuroblast phenotype by reducing basal Numb levels. We propose that aPKC and Cul3 promote basal Numb localization, which is required to downregulate Notch signaling and promote differentiation in neuroblast progeny.

developmental biology↗

A multi-informatic description of neural differentiation in the Drosophila type-II neuroblast lineages

To adopt terminal neural fates, neural progenitors respond to a combination of molecular factors, the interplay between which remains difficult to untangle. In this work, we interrogated the type-II neuroblast lineages in the developing Drosophila brain using targeted single-cell mRNA sequencing. We used pseudotime analysis to group cells by their differentiation state and subsequently used marker gene analysis to identify genes that may play a role in neural fate specification. To aid the candidate gene selection process, we created MiCV, a scRNA-seq data visualization web tool that integrates results from the multifaceted analysis, displays the co-expression pattern of multiple genes, and provides an automated gene function curating feature. In situ profiling of these mRNAs further recovered the spatial information lacking in the single-cell data. Combining prior knowledge, in silico analysis, and in situ evidence, we characterize the molecular landscape of the developing Drosophila type-II neuroblast lineages and provide a roadmap for navigating the more complex brains.

neuroscience↗

BonVision - an open-source software to create and control visual environments

Real-time rendering of closed-loop visual environments is necessary for next-generation understanding of brain function and behaviour, but is prohibitively difficult for non-experts to implement and is limited to few laboratories worldwide. We developed BonVision as an easy-to-use open-source software for the display of virtual or augmented reality, as well as standard visual stimuli. As the architecture is based on the open-source Bonsai graphical programming language, BonVision benefits from native integration with experimental hardware. BonVision therefore enables easy implementation of closed-loop experiments, including real-time interaction with deep neural networks and communication with behavioural and physiological measurement and manipulation devices.

neuroscience↗

Continual inactivation of stem cell functional identity genes stabilizes progenitor commitment

Expansion of the pool of stem cells that indirectly generate differentiated cells through intermediate progenitors drives vertebrate brain evolution. Due to a lack of lineage information, mechanistic investigation of the competency of stem cells to generate intermediate progenitors remains impossible. Fly larval brain neuroblasts provide excellent in vivo models for investigating the regulation of stem cell functionality during neurogenesis. Type II neuroblasts undergo indirect neurogenesis by dividing asymmetrically to generate a neuroblast and a progeny that commits to an intermediate progenitor (INP) identity. We identified Tailless (Tll) as the master regulator that maintains type II neuroblast functional identity, including the competency to generate INPs. Successive inactivation during INP commitment inhibits tll activation by Notch, preventing INPs from reacquiring neuroblast functionality. We propose that the continual inactivation of neural stem cell functional identity genes by histone deacetylation allows intermediate progenitors to stably commit to generating diverse differentiated cells during indirect neurogenesis.

developmental biology↗

SparkINFERNO: A scalable high-throughput pipeline for inferring molecular mechanisms of non-coding genetic variants

SummaryWe report SparkINFERNO (Spark-based INFERence of the molecular mechanisms of NOn-coding genetic variants), a scalable bioinformatics pipeline characterizing noncoding GWAS association findings. SparkINFERNO prioritizes causal variants underlying GWAS association signals and reports relevant regulatory elements, tissue contexts, and plausible target genes they affect. To achieve this, the SparkINFERNO algorithm integrates GWAS summary statistics with large-scale collection of functional genomics datasets spanning enhancer activity, transcription factor binding, expression quantitative trait loci, and other functional datasets across more than 400 tissues and cell types. Scalability is achieved by an underlying API implemented using Apache Spark and Giggle-based genomic indexing. We evaluated SparkINFERNO on large GWAS studies and show that SparkINFERNO is more than 60-times efficient and scales with data size and amount of computational resources. AvailabilitySparkINFERNO runs on clusters or a single server with Apache Spark environment, and is available at https://bitbucket.org/wanglab-upenn/SparkINFERNO or https://hub.docker.com/r/wanglab/spark-inferno. Contactlswang@pennmedicine.upenn.edu

bioinformatics↗

jYCaMP: An optimized calcium indicator for two-photon imaging at fiber laser wavelengths

State-of-the-art GFP-based calcium indicators do not undergo efficient two-photon excitation at wavelengths above 1000 nm, for which inexpensive and powerful industrial femtosecond lasers are available. Here we report jYCaMP1, a yellow variant of jGCaMP7 that outperforms its parent in mice and flies at excitation wavelengths above 1000 nm and enables improved two-color calcium imaging with RFP-based indicators.

neuroscience↗

The Hrq1 helicase stimulates Pso2 translesion nuclease activity to promote DNA inter-strand crosslink repair

DNA inter-strand crosslink (ICL) repair requires a complicated network of DNA damage response pathways. Removal of these lesions is vital as they are physical barriers to essential DNA processes that require the separation of duplex DNA, such as replication and transcription. The Fanconi anemia (FA) pathway is the principle mechanism for ICL repair in metazoans and is coupled to replication. In Saccharomyces cerevisiae, a degenerate FA pathway is present, but ICLs are predominantly repaired by a pathway involving the Pso2 nuclease that is hypothesized to digest through the lesion to provide access for translesion polymerases. However, Pso2 lacks translesion nuclease activity in vitro, and mechanistic details of this pathway are lacking, especially relative to FA. We recently identified the Hrq1 helicase, a homolog of the disease-linked RECQL4, as a novel component of Pso2- mediated ICL repair. Here, we show that Hrq1 stimulates the Pso2 nuclease in a mechanism that requires Hrq1 catalytic activity. Importantly, Hrq1 also stimulates Pso2 translesion nuclease activity through a site- specific ICL in vitro. Stimulation of Pso2 nuclease activity is specific to eukaryotic RecQ4 subfamily helicases, and Hrq1 likely interacts with Pso2 through their N-terminal domains. These results advance our understanding of FA-independent ICL repair and establish a role for the RecQ4 helicases in the repair of these dangerous lesions.

biochemistry↗

Regulation of amino acid and nucleotide metabolism by crustacean hyperglycemic hormone in the muscle and hepatopancreas of the crayfish Procambarus clarkii

To comprehensively characterize the metabolic roles of crustacean hyperglycemic hormone (CHH), metabolites in two CHH target tissues of the crayfish Procambarus clarkii, whose levels were significantly different between CHH-silenced and saline-treated control animals, were analyzed using bioinformatics tools provided by an on-line analysis suite (MetaboAnalyst). Analysis with Metabolic Pathway Analysis (MetPA) indicated that in the muscle Glyoxylate and dicarboxylate metabolism, Nicotinate and nicotinamide metabolism, Alanine, aspartate and glutamate metabolism, Pyruvate metabolism, and Nitrogen metabolism were significantly affected by silencing of CHH gene expression at 24 hours post injection (hpi), while only Nicotinate and nicotinamide metabolism remained significantly affected at 48 hpi. In the hepatopancreas, silencing of CHH gene expression significantly impacted, at 24 hpi, Pyruvate metabolism and Glycolysis or gluconeogenesis, and at 48 hpi, Glycine, serine and threonine metabolism. Moreover, analysis using Metabolite Set Enrichment Analysis (MSEA) showed that many metabolite sets were significantly affected in the muscle at 24hpi, including Ammonia recycling, Nicotinate and nicotinamide metabolism, Pyruvate metabolism, Purine metabolism, Warburg effect, Citric acid cycle, and metabolism of several amino acids, and at 48 hpi only Nicotinate and nicotinamide metabolism, Glycine and serine metabolism, and Ammonia recycling remained significantly affected. In the hepatopancreas, MSEA analysis showed that Fatty acid biosynthesis was significantly impacted at 24 hpi. Finally, in the muscle, levels of several amino acids decreased significantly, while those of 5 other amino acids or related compounds significantly increased in response to CHH gene silencing. Levels of metabolites related to nucleotide metabolism significantly decreased across the board at both time points. In the hepatopancreas, the effects were comparatively minor with only levels of thymine and urea being significantly decreased at 24 hpi. The combined results showed that the metabolic effects of silencing CHH gene expression were far more diverse than suggested by previous studies that emphasized on carbohydrate and energy metabolism. Based on the results, metabolic roles of CHH on the muscle and hepatopancreas were summarized and discussed.

zoology↗

P granules protect RNA interference genes from silencing by piRNAs

P granules are perinuclear condensates in C. elegans germ cells proposed to serve as hubs for self/non-self RNA discrimination by Argonautes. We report that a mutant (meg-3 meg-4) that does not assemble P granules in primordial germ cells loses competence for RNA-interference over several generations and accumulates silencing small RNAs against hundreds of endogenous genes, including the RNA-interference genes rde-11 and sid-1. In wild-type, rde-11 and sid-1 transcripts are heavily targeted by piRNAs, accumulate in P granules, but maintain expression. In the primordial germ cells of meg-3 meg-4 mutants, rde-11 and sid-1 transcripts disperse in the cytoplasm with the small RNA biogenesis machinery, become hyper-targeted by secondary sRNAs, and are eventually silenced. Silencing requires the PIWI-class Argonaute PRG-1 and the nuclear Argonaute HRDE-1 that maintains trans-generational silencing of piRNA targets. These observations support a \"safe harbor\" model for P granules in protecting germline transcripts from piRNA-initiated silencing.

molecular biology↗

RNASeqR: an R package for automated two-group RNA-Seq analysis workflow

RNA-Seq analysis has revolutionized researchers understanding of the transcriptome in biological research. Assessing the differences in transcriptomic profiles between tissue samples or patient groups enables researchers to explore the underlying biological impact of transcription. RNA-Seq analysis requires multiple processing steps and huge computational capabilities. There are many well-developed R packages for individual steps; however, there are few R/Bioconductor packages that integrate existing software tools into a comprehensive RNA-Seq analysis and provide fundamental end-to-end results in pure R environment so that researchers can quickly and easily get fundamental information in big sequencing data. To address this need, we have developed the open source R/Bioconductor package, RNASeqR. It allows users to run an automated RNA-Seq analysis with only six steps, producing essential tabular and graphical results for further biological interpretation. The features of RNASeqR include: six-step analysis, comprehensive visualization, background execution version, and the integration of both R and command-line software. RNASeqR provides fast, light-weight, and easy-to-run RNA-Seq analysis pipeline in pure R environment. It allows users to efficiently utilize popular software tools, including both R/Bioconductor and command-line tools, without predefining the resources or environments. RNASeqR is freely available for Linux and macOS operating systems from Bioconductor (https://bioconductor.org/packages/release/bioc/html/RNASeqR.html).

bioinformatics↗

Heterochromatin and the Synaptonemal Complex Maintain Homologous Centromere Interactions in Mouse Spermatocytes

In meiosis, crossovers between homologous chromosomes link them together. This enables them to attach to microtubules of the meiotic spindle as a unit, such that the homologs will be pulled away from one another at anaphase I. Homologous pairs can sometimes fail to become linked by crossovers. In some organisms, these non-exchange partners are still able segregate properly. In several organisms, associations between the centromeres of non-exchange partners occur in meiotic prophase. These associations have been proposed to promote segregation in meiosis I. But how centromere pairing could promote subsequent proper segregation is unclear. Here we report that meiotic centromere pairing if chromosomes in mouse spermatocytes allows the formation of an association between chromosome pairs. We find that peri-centromeric heterochromatin connections tether the centromeres of chromosome pairs after dissolution of centromere paring. Our results suggest that, in mouse spermatocytes, heterochromatin maintains the association of chromosome centromeres in the absence crossing-over.

cell biology↗