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Cai, T.

Publications and source records attributed to Cai, T..

34 records · Page 2Linked to original sources

DeepREAL: A Deep Learning Powered Multi-scale Modeling Framework Towards Predicting Out-of-distribution Receptor Activity of Ligand Binding

Drug discovery has witnessed intensive exploration of the problem of drug-target physical interactions over two decades, however, a strong drug binding affinity to a single target often fails to translate into desired clinical outcomes. A critical knowledge gap needs to be filled for correlating drug-target interactions with phenotypic responses: predicting the receptor activities or function selectivity upon the ligand binding (i.e., agonist vs. antagonist) on a genome-scale and for novel chemicals. Two major obstacles compound the difficulty on this direction: known data of receptor activity is far too scarce to train a robust model in light of genome-scale applications, and real-world applications need to deploy a model on data from various shifted distributions. To address these challenges, we have developed an end-to-end deep learning framework, DeepREAL, for multi-scale modeling of genome-wide receptor activities of ligand binding. DeepREAL utilizes self-supervised learning on tens of millions of protein sequences and pre-trained binary interaction classification to solve the data distribution shift and data scarcity problems. Extensive benchmark studies that simulate real-world scenarios demonstrate that DeepREAL achieves state-of-the-art performance in out-of-distribution settings.

bioinformatics↗

Degrading intestinal DAF-2 nearly doubles Caenorhabditis elegans lifespan without affecting development or reproduction

Twenty-eight years following the breakthrough discovery that a single-gene mutation of daf-2 can double the lifespan of Caenorhabditis elegans, it remains unclear where this gene, which encodes an insulin/IGF-1 receptor, is expressed and where it acts to regulate aging. Here, by inserting DNA sequences of fluorescent tags into the genomic locus of daf-2 and that of its downstream transcription factor daf-16, we determined that both genes are expressed in most or all tissues from embryos through adulthood, in line with their diverse functions. Using tissue-specific auxin-induced protein degradation, we determined that both DAF-2 and DAF-16 act in the intestine to regulate organismal aging. Strikingly, loss of DAF-2 in the intestine nearly doubled C. elegans lifespan but did not produce the adverse developmental or reproductive phenotypes associated with genetic daf-2 mutants. These findings unify the mechanism of lifespan regulation by genes and that by dietary restriction, and begin to focus anti-aging research on nutrient supply. HighlightsO_LIdaf-2 and daf-16 are expressed in most or all cells of C. elegans using genome editing. C_LIO_LIDAF-2 and DAF-16 both regulate lifespan from the intestine as determined using auxin-induced protein degradation. C_LIO_LIReduced insulin signaling in the intestine nearly doubles C. elegans lifespan without adverse effects on development or reproduction. C_LIO_LILifespan regulation by genes and dietary restriction are unified by intestinal supply of nutrients and metabolism. C_LI

cell biology↗

Somatic genetics analysis of sleep in adult mice

Classical forward and reverse mouse genetics approaches require germline mutations and, thus, are unwieldy to study sleep functions of essential genes or redundant pathways. It is also time-consuming to conduct electroencephalogram/electromyogram-based mouse sleep screening owning to labor-intensive surgeries and genetic crosses. Here, we describe a highly accurate SleepV (video) system and adeno-associated virus (AAV)-based adult brain chimeric (ABC)- expression/knockout (KO) platform for somatic genetics analysis of sleep in adult mice. A pilot ABC-expression screen identifies CREB and CRTC1, of which constitutive or inducible expression significantly reduces quantity and quality of non-rapid eye movement sleep. Whereas ABC-KO of exon 13 of Sik3 by AAV-Cre injection in Sik3-E13flox/flox adult mice phenocopies Sleepy (Sik3Slp/+) mice, ABC-CRISPR of Slp/Sik3 reverses hypersomnia of Sleepy mice, indicating a direct role of SLP/SIK3 kinase in sleep regulation. Multiplex ABC-CRISPR of both orexin/hypocretin receptors causes narcolepsy-like episodes, enabling one-step analysis of redundant genes in adult mice. Finally, ABC-expression/KO screen identifies Ankrd63 and NR1 as two potentially new sleep regulators. Therefore, this somatic genetics approach should facilitate high-throughput analysis of sleep regulatory genes, especially for essential or redundant genes, in adult mice by skipping the mouse development and genetic crosses.

neuroscience↗

Arginine Methylation Regulates SARS-CoV-2 Nucleocapsid Protein Function and Viral Replication

Viral proteins are known to be methylated by host protein arginine methyltransferases (PRMTs) playing critical roles during viral infections. Herein, we show that PRMT1 methylates SARS-CoV-2 nucleocapsid (N) protein at residues R95 and R177 within RGG/RG sequences. Arginine methylation of N protein was confirmed by immunoblotting viral proteins extracted from SARS-CoV-2 virions isolated by cell culture. We demonstrate that arginine methylation of N protein is required for its RNA binding capacity, since treatment with a type I PRMT inhibitor (MS023) or substitution of R95K or R177K inhibited interaction with the 5-UTR of the SARS-CoV-2 genomic RNA. We defined the N interactome in HEK293 cells with or without MS023 treatment and identified PRMT1 and many of its RGG/RG substrates including the known interactor, G3BP1, and other components of stress granules (SG). Methylation of N protein at R95 regulates another function namely its property to suppress the formation of SGs. MS023 treatment or R95K substitution blocked N-mediated suppression of SGs. Also, the co-expression of methylarginine reader TDRD3 quenched N-mediated suppression of SGs in a dose-dependent manner. Finally, pre-treatment of VeroE6 cells with MS023 significantly reduced SARS-CoV-2 replication. With type I PRMT inhibitors being in clinical trials for cancer treatment, inhibiting arginine methylation to target the later stages of the viral life cycle such as viral genome packaging and assembly of virions may be an additional therapeutic application of these drugs.

molecular biology↗

Semi-supervised Calibration of Risk with Noisy Event Times (SCORNET) Using Electronic Health Record Data

Leveraging large-scale electronic health record (EHR) data to estimate survival curves for clinical events can enable more powerful risk estimation and comparative effectiveness research. However, use of EHR data is hindered by a lack of direct event times observations. Occurrence times of relevant diagnostic codes or target disease mentions in clinical notes are at best a good approximation of the true disease onset time. On the other hand, extracting precise information on the exact event time requires laborious manual chart review and is sometimes altogether infeasible due to a lack of detailed documentation. Current status labels - binary indicators of phenotype status during follow up - are significantly more efficient and feasible to compile, enabling more precise survival curve estimation given limited resources. Existing survival analysis methods using current status labels focus almost entirely on supervised estimation, and naive incorporation of unlabeled data into these methods may lead to biased results. In this paper we propose Semi-supervised Calibration of Risk with Noisy Event Times (SCORNET), which yields a consistent and efficient survival curve estimator by leveraging a small size of current status labels and a large size of imperfect surrogate features. In addition to providing theoretical justification of SCORNET, we demonstrate in both simulation and real-world EHR settings that SCORNET achieves efficiency akin to the parametric Weibull regression model, while also exhibiting non-parametric flexibility and relatively low empirical bias in a variety of generative settings.

bioinformatics↗

Potentiating CD8+ T cell antitumor activity by targeting the PCSK9/LDLR axis

Metabolic regulation has proven to play a critical role in T cell antitumor immunity. Cholesterol metabolism is a key component of this response but remains largely unexplored. Herein, we found that the LDL receptor (LDLR), which has been previously identified as a transporter for cholesterol and fatty acids, plays a pivotal role in regulating CD8+ T cell antitumor activity, with the genetic ablation of LDLR significantly attenuating CD8+ T cell activation and clonal expansion. Additionally, we found that LDLR interacts with the T-cell receptor (TCR) signalosome and regulates TCR signaling, facilitating CD8+ T cell activation and effector function. Furthermore, we found that the tumor microenvironment downregulates CD8+ T cell LDLR levels and TCR signaling via tumor cell-derived PCSK9, which binds and prevents the recycling of LDLR and TCR into the plasma membrane. Our findings indicate that genetic deletion or pharmacological inhibition of PCSK9 in tumor cells can enhance the antitumor activity of CD8+ T cells by alleviating the tumor microenvironments suppressive effect on CD8+ T cells and consequently inhibit tumor progression. While previously established as a hyperlipidemia target, this study highlights PCSK9 as a potential target for cancer immunotherapy as well.

immunology↗

A deep learning framework for elucidating whole-genome chemical interaction space

Molecular interaction is the foundation of biological process. Elucidation of genome-wide binding partners of a biomolecule will address many questions in biomedicine. However, ligands of a vast number of proteins remain elusive. Existing methods mostly fail when the protein of interest is dissimilar from those with known functions or structures. We develop a new deep learning framework DISAE that incorporates biological knowledge into self-supervised learning techniques for predicting ligands of novel unannotated proteins on a genome-scale. In the rigorous benchmark studies, DISAE outperforms state-of-the-art methods by a significant margin. The interpretability analysis of DISAE suggests that it learns biologically meaningful information. We further use DISAE to assign ligands to human orphan G-Protein Coupled Receptors (GPCRs) and to cluster the human GPCRome by integrating their phylogenetic and ligand relationships. The promising results of DISAE open an avenue for exploring the chemical landscape of entire sequenced genomes.

bioinformatics↗

Genome-wide Prediction of Small Molecule Binding to Remote Orphan Proteins Using Distilled Sequence Alignment Embedding

Endogenous or surrogate ligands of a vast number of proteins remain unknown. Identification of small molecules that bind to these orphan proteins will not only shed new light into their biological functions but also provide new opportunities for drug discovery. Deep learning plays an increasing role in the prediction of chemical-protein interactions, but it faces several challenges in protein deorphanization. Bioassay data are highly biased to certain proteins, making it difficult to train a generalizable machine learning model for the proteins that are dissimilar from the ones in the training data set. Pre-training offers a general solution to improving the model generalization, but needs incorporation of domain knowledge and customization of task-specific supervised learning. To address these challenges, we develop a novel protein pre-training method, DIstilled Sequence Alignment Embedding (DISAE), and a module-based fine-tuning strategy for the protein deorphanization. In the benchmark studies, DISAE significantly improves the generalizability and outperforms the state-of-the-art methods with a large margin. The interpretability analysis of pre-trained model suggests that it learns biologically meaningful information. We further use DISAE to assign ligands to 649 human orphan G-Protein Coupled Receptors (GPCRs) and to cluster the human GPCRome by integrating their phylogenetic and ligand relationships. The promising results of DISAE open an avenue for exploring the chemical landscape of entire sequenced genomes.

systems biology↗

Machine Learning-Based Protein Microarray Digital Assay Analysis

Serial measurement of a large panel of protein biomarkers near the bedside could provide a promising pathway to transform the critical care of acutely ill patients. However, attaining the combination of high sensitivity and multiplexity with a short assay turnaround poses a formidable technological challenge. Here, we developed a rapid, accurate, and highly multiplexed microfluidic digital immunoassay by incorporating machine learning-based autonomous image analysis. The assay achieved 14-plexed biomarker detection at concentrations < 10pg/mL with a sample volume < 10 L, including all processes from sampling to analyzed data delivery within 30 min, while only requiring a 5-min assay incubation. The assay procedure applied both a spatial-spectral microfluidic encoding scheme and an image data analysis algorithm based on machine learning with a convolutional neural network (CNN) for pre-equilibrated single-molecule protein digital counting. This unique approach remarkably reduced errors facing the high-capacity multiplexing of digital immunoassay at low protein concentrations. Longitudinal data obtained for a panel of 14 serum cytokines in human patients receiving chimeric antigen receptor-T (CAR-T) cell therapy manifested the powerful biomarker profiling capability and great potential of the assay for its translation to near-real-time bedside immune status monitoring.

bioengineering↗

sureLDA: A Multi-Disease Automated Phenotyping Method for the Electronic Health Record

ObjectiveA major bottleneck hindering utilization of electronic health record (EHR) data for translational research is the lack of precise phenotype labels. Chart review as well as rule-based and supervised phenotyping approaches require laborious expert input, hampering applicability to studies that require many phenotypes to be defined and labeled de novo. Though ICD codes are often used as surrogates for true labels in this setting, these sometimes suffer from poor specificity. We propose a fully automated topic modeling algorithm to simultaneously annotate multiple phenotypes. MethodssureLDA is a label-free multidimensional phenotyping method. It first uses the PheNorm algorithm to initialize probabilities based on two surrogate features for each target phenotype, and then leverages these probabilities to constrain the Latent Dirichlet Allocation (LDA) topic model to generate phenotype-specific topics. Finally, it combines phenotype-feature counts with surrogates via clustering ensemble to yield final phenotype probabilities. ResultssureLDA achieves reliably high accuracy and precision across a range of simulated and real-world phenotypes. Its performance is robust to phenotype prevalence and relative informativeness of surogate versus non-surrogate features. It also exhibits powerful feature selection properties. DiscussionsureLDA combines attractive properties of PheNorm and LDA to achieve high accuracy and precision robust to diverse phenotype characteristics. It offers particular improvement for phenotypes insufficiently captured by a few surrogate features. Moreover, sureLDAs feature selection ability enables it to handle high feature dimensions and produce interpretable computational phenotypes. ConclusionsureLDA is well suited toward large-scale EHR phenotyping for highly multi-phenotype applications such as PheWAS.

bioinformatics↗

The Nucleocapsid Protein of SARS-CoV-2 Abolished Pluripotency in Human Induced Pluripotent Stem Cells

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is raging across the world, leading to a global mortality rate of 3.4% (estimated by World Health Organization in March 2020). As a potential vaccine and therapeutic target, the nucleocapsid protein of SARS-CoV-2 (nCoVN) functions in packaging the viral genome and viral self-assembly. To investigate the biological effects of nCoVN to human stem cells, genetically engineered human induced pluripotent stem cells (iPSC) expressing nCoVN (iPSC-nCoVN) were generated by lentiviral expression systems, in which the expression of nCoVN could be induced by the doxycycline. The proliferation rate of iPSC-nCoVN was decreased. Unexpectedly, the morphology of iPSC started to change after nCoVN expression for 7 days. The pluripotency marker TRA-1-81 were not detectable in iPSC-nCoVN after a four-day induction. Meanwhile, iPSC-nCoVN lost the ability for differentiation into cardiomyocytes with a routine differentiation protocol. The RNA-seq data of iPSC-nCoVN (induction for 30 days) and immunofluorescence assays illustrated that iPSC-nCoVN were turning to fibroblast-like cells. Our data suggested that nCoVN disrupted the pluripotent properties of iPSC and turned them into other types of cells, which provided a new insight to the pathogenic mechanism of SARS-CoV-2.

cell biology↗

Modulation of the canonical Wnt activity by androgen signaling in prostate epithelial basal stem cells

Both the canonical Wnt signaling and androgen signaling are important factors regulating prostate organogenesis. How these two pathways crosstalk to regulate prostate stem cell functions remain unclear. Here, we show that while canonical Wnt activity is required for prostate basal stem cell multipotency in vivo, ectopic Wnt activity does not promote basal-to-luminal cell differentiation. We provide evidence that androgen signaling may keep Wnt activity in check. In prostate organoid culture from basal cells, dihydrotestosterone (DHT) antagonizes R-spondin-stimulated organoid growth in a concentration-dependent manner. Molecular analyses of organoids under different treatment conditions showed that androgen signaling down-regulated the expressions of a Wnt reporter as well as many Wnt target genes. Pathway analysis and gene set enrichment analysis of organoid RNA-seq data also revealed the canonical Wnt signaling as a key pathway distinguishing organoids treated with or without DHT. Notably, DHT treatment enhanced AR and {beta}-catenin binding in the nuclei of prostate organoids, providing possible mechanistic clues. Our results reveal a critical role of AR signaling in modulating canonical Wnt activity in prostate basal cells to regulate their multipotency.

developmental biology↗

Determination of secretory granule maturation times in pancreatic islet beta-cells by serial block face scanning electron microscopy

It is shown how serial block-face electron microscopy (SBEM) of insulin-secreting beta cells in wild-type mouse pancreatic islets of Langerhans can be used to determine maturation times of secretory granules. Although SBEM captures the beta cell structure at a snapshot in time, the observed ultrastructure can be considered representative of a dynamic equilibrium state of the cells since the pancreatic islets are maintained in culture in approximate homeostasis. It is found that 7.2{+/-}1.2% ({+/-}st. dev.) of the beta cell volume is composed of secretory granule dense-cores exhibiting angular shapes surrounded by wide (typically {gtrsim}100 nm) electron-lucent halos. These organelles are identified as mature granules that store insulin for regulated release through the plasma membrane, with a release time of 96{+/-}12 hours, as previously obtained from pulsed 35S-radiolabeling of cysteine and methionine. Analysis of beta cell 3D volumes reveals a subpopulation of secretory organelles without electron-lucent halos, identified as immature secretory granules. Another subpopulation of secretory granules is found with thin (typically [lsim]30 nm) electron-lucent halos, which are attributed to immature granules that are transforming from proinsulin to insulin by action of prohormone convertases. From the volume ratio of proinsulin in the immature granules to insulin in the mature granules, we estimate that the newly formed immature granules remain in morphologically-defined immature states for an average time of 135{+/-}14 minutes, and the immature transforming granules for an average time of 130{+/-}17 minutes.

biophysics↗

High-throughput Multimodal Automated Phenotyping (MAP) with Application to PheWAS

ObjectiveElectronic health records (EHR) linked with biorepositories are a powerful platform for translational studies. A major bottleneck exists in the ability to phenotype patients accurately and efficiently. The objective of this study was to develop an automated high-throughput phenotyping method integrating International Classification of Diseases (ICD) codes and narrative data extracted using natural language processing (NLP).\n\nMethodWe developed a mapping method for automatically identifying relevant ICD and NLP concepts for a specific phenotype leveraging the UMLS. Aggregated ICD and NLP counts along with healthcare utilization were jointly analyzed by fitting an ensemble of latent mixture models. The MAP algorithm yields a predicted probability of phenotype for each patient and a threshold for classifying subjects with phenotype yes/no. The algorithm was validated using labeled data for 16 phenotypes from a biorepository and further tested in an independent cohort PheWAS for two SNPs with known associations.\n\nResultsThe MAP algorithm achieved higher or similar AUC and F-scores compared to the ICD code across all 16 phenotypes. The features assembled via the automated approach had comparable accuracy to those assembled via manual curation (AUCMAP 0.943, AUCmanual 0.941). The PheWAS results suggest that the MAP approach detected previously validated associations with higher power when compared to the standard PheWAS method based on ICD codes.\n\nConclusionThe MAP approach increased the accuracy of phenotype definition while maintaining scalability, facilitating use in studies requiring large scale phenotyping, such as PheWAS.

bioinformatics↗

Circadian gene Clock regulates mitochondrial morphology and functions by posttranscriptional way

Many daily activities are under the control of circadian clock, including nutrition metabolism and energy generation. Mitochondria, as the core factories of oxidizing substrates and producing ATP, undergo changes in quantity and morphology to adapt to the demand for energy. It has been demonstrated that mitochondrial gene expression, dynamics and functions are all affected by circadian clock. Here, we demonstrated that circadian gene Clock affects the number, architecture and function of mitochondria via posttranscriptional regulation of Drp1. Clock{Delta}19 leads to fragmented mitochondria accompanied with the loss of membrane potential, excessive ROS accumulation and decreased mitochondrial respiration and ATP generation. Clock{Delta}19 mice exhibit disordered lipid metabolism and evident nonalcoholic fatty liver disease (NAFLD), which are rescued by treatment with the mitochondrial fission inhibitor Mdivi-1. These results suggest a strong relationship between Clock, mitochondrial dynamics and metabolic diseases and provide a new perspective on disordered circadian clock and related diseases.

cell biology↗

Genetic validation of bipolar disorder identified by automated phenotyping using electronic health records

Bipolar disorder (BD) is a heritable mood disorder characterized by episodes of mania and depression. Although genomewide association studies (GWAS) have successfully identified genetic loci contributing to BD risk, sample size has become a rate-limiting obstacle to genetic discovery. Electronic health records (EHRs) represent a vast but relatively untapped resource for high-throughput phenotyping. As part of the International Cohort Collection for Bipolar Disorder (ICCBD), we previously validated automated EHR-based phenotyping algorithms for BD against in-person diagnostic interviews (Castro et al. 2015). Here, we establish the genetic validity of these phenotypes by determining their genetic correlation with traditionally-ascertained samples. Case and control algorithms were derived from structured and narrative text in the Partners Healthcare system comprising more than 4.6 million patients over 20 years. Genomewide genotype data for 3,330 BD cases and 3,952 controls of European ancestry were used to estimate SNP-based heritability (h2g) and genetic correlation(rg) between EHR-based phenotype definitions and traditionally-ascertained BD cases in GWAS by the ICCBD and Psychiatric Genomics Consortium (PGC) using LD score regression. We evaluated BD cases identified using 4 EHR-based algorithms: an NLP-based algorithm (95-NLP) and 3 rule-based algorithms using codified EHR with decreasing levels of stringency - \"coded-strict\", \"coded-broad\", and \"coded-broad based on a single clinical encounter\" (coded-broad-SV). The analytic sample comprised 862 95-NLP, 1,968 coded-strict, 2,581 coded-broad, 408 coded-broad-SV BD cases, and 3,952 controls. The estimated h2g were 0.24 (p=0.015), 0.09 (p=0.064), 0.13 (p=0.003), 0.00 (p=0.591) for 95-NLP, coded-strict, coded-broad and coded-broad-SV BD, respectively. The h2g for all EHR-based cases combined except coded-broad-SV (excluded due to 0 h2g) was 0.12 (p=0.004). These h2g were lower or similar to the h2g observed by the ICCBD+PGCBD (0.23, p=3.17E-80, total N=33,181). However, the rg between ICCBD+PGCBD and the EHR-based cases were high for 95-NLP (0.66, p=3.69x10-5), coded-strict (1.00, p=2.40x10-4), and coded-broad (0.74, p=8.11x10-7). The rg between EHR-based BDs ranged from 0.90 to 0.98. These results provide the first genetic validation of automated EHR-based phenotyping for BD and suggest that this approach identifies cases that are highly genetically correlated with those ascertained through conventional methods. High throughput phenotyping using the large data resources available in EHRs represents a viable method for accelerating psychiatric genetic research.

genetics↗