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Cao, C.

Publications and source records attributed to Cao, C..

At least 73 records · Page 4Linked to original sources

PRE-TRAINING WITH A RATIONAL APPROACH FOR ANTIBODY

Antibodies represent a specific class of proteins produced by the adaptive immune system in response to pathogens. Mining the information embedded in antibody amino acid sequences can benefit both antibody property prediction and novel therapeutic development. Protein-specific pre-training models have been used to extract latent representations from protein sequences, structural, functional, and homologous information. However, compared to other proteins, antibodies possess unique features that should be incorporated using specifically designed training methods, so there is still room for improvement in pre-training models for antibody sequences. On the one hand, existing protein pre-training models primarily utilize language models without fully considering the differences between protein sequences and language sequences. In this study, we present a Pre-trained model of Antibody sequences trained with a Rational Approach for antibodies (PARA), which employs a strategy conforming to antibody sequence patterns and an advanced natural language processing self-encoding model structure. We demonstrate PARAs performance on several tasks by comparing it to various published pre-training models of antibodies. The results show that PARA significantly outperforms existing models on these tasks, suggesting that PARA has an advantage in capturing antibody sequence information. We believe that the antibody latent representation provided by PARA can substantially facilitate studies in relevant areas. PARA is available at https://github.com/xtalpi-xic.

bioinformatics↗

RNA in situ conformation sequencing reveals novel long-range RNA structures with impact on splicing

Over past years, long-range RNA structure has emerged as a factor that is fundamental to alternative splicing regulation. Since an increasing number of human disorders are now being associated with splicing defects, it is essential to develop methods that assess long-range RNA structure experimentally. RNA in situ conformation sequencing (RIC-seq) is the method that recapitulates RNA structure within physiological RNA-protein complexes. In this work, we juxtapose RIC-seq experiments conducted in eight human cell lines with pairs of conserved complementary regions (PCCRs) that were predicted in silico. We show statistically that RIC-seq support strongly correlates with PCCR properties such as equilibrium free energy, presence of compensatory substitutions, and occurrence of A-to-I RNA editing sites and forked eCLIP peaks. Based on these findings, we prioritize PCCRs according to their RIC-seq support and show experimentally using antisense nucleotides and minigene mutagenesis that PCCRs in two disease-associated genes, PHF20L1 and CASK, impact alternative splicing. In sum, we demonstrate how RIC-seq experiments can be used to discover functional long-range RNA structures, and particularly those that regulate alternative splicing.

molecular biology↗

RNAcontacts, a pipeline for predicting contacts from RNA proximity ligation assays

BackgroundHigh-throughput RNA proximity ligation assays are molecular methods that simultaneously analyze spatial proximity of many RNAs in living cells. Their principle is based on cross-linking, fragmentation, and consequent religation of RNAs followed by high-throughput sequencing. The generated fragments have two distinct types of splits, one resulting from pre-mRNA splicing, and the other resulting from ligating spatially close RNA strands. FindingsHere, we present RNAcontacts, a universal pipeline for detecting RNA-RNA contacts in high-throughput RNA proximity ligation assays. It circumvents the inherent problem of mapping sequences with two distinct split types using a two-pass alignment, in which splice junctions are inferred from a control RNA-seq experiment on the first pass and then provided to the aligner on the second pass as bona fide introns. This approach allows for a more sensitive detection of RNA contacts and has higher specificity with respect to splice junctions that are present in the biological sample in comparison to previously developed methods. RNAcontacts extracts contacts, clusters their ligation points, computes the read support, and generates tracks for the visualization through the UCSC Genome Browser. It is implemented in a reproducible and scalable workflow management system Snakemake that allows fast and uniform processing of multiple datasets. ConclusionsRNAcontacts represents a generic pipeline for the detection of RNA contacts that can be used with any proximity ligation method as long as one of the interacting partners is RNA. RNAcontacts is available via github at https://github.com/smargasyuk/RNAcontacts/

bioinformatics↗

Spatial transcriptomics reveals distinct and conserved tumor core and edge architectures that predict survival and targeted therapy response

We performed the first integrative single-cell and spatial transcriptomic analysis on HPV-negative oral squamous cell carcinoma (OSCC) to comprehensively characterize tumor core (TC) and leading edge (LE) transcriptional architectures. We show that the TC and LE are characterized by unique transcriptional profiles, cellular compositions, and ligand-receptor interactions. We demonstrate that LE regions are conserved across multiple cancers while TC states are more tissue specific. Additionally, we found our LE gene signature is associated with worse clinical outcomes while the TC gene signature is associated with improved prognosis across multiple cancer types. Finally, using an in silico modeling approach, we describe spatially-regulated patterns of cell development in OSCC that are predictably associated with drug response. Our work provides pan-cancer insights into TC and LE biologies, a platform for data exploration (http://www.pboselab.ca/spatial_OSCC/) and is foundational for developing novel targeted therapies.

cancer biology↗

Cereblon controls the timing of muscle differentiation in Ciona embryos

Thalidomide has a dark history as a teratogen, but in recent years it has been shown to function as a chemotherapeutic agent. Thalidomide binds cereblon, a component of E3 ubiquitin ligase complex and modifies its degradation targets. Despite these insights, remarkably little is known about the normal function of cereblon in development. Here, we employ the simple proto-vertebrate model, Ciona intestinalis, to address this question. We observed a "hotspot" of Crbn expression in the developing tail muscles and identify its enhancer containing both Myod activator sites and a Snail repressive element. Overexpression of Crbn in tail muscles decreases expression of contractility genes. We suggest that this reduction is due to premature degradation of Tbx6. Drug inhibition studies using lenalidomide, a derivative of thalidomide, lead to a striking increase of Crbn expression. This autofeedback regulation could be induced by neomorphic degradation of Snail, contributing to the efficacy of lenalidomide in treating metastatic melanoma. In summary, our analysis of Crbn suggests that its normal function in Ciona is to time expression of contractility genes during muscle differentiation thereby ensuring coordination of tail morphogenesis and hatching of swimming tadpoles.

developmental biology↗

CRIC-seq reveals positional rule of PTBP1-mediated long-range RNA looping in splicing regulation

RNA-binding proteins bind at different positions of pre-mRNA molecules to promote or reduce the usage of a particular exon. Seeking to understand the working principle of these positional effects, we develop a CRIC-seq method to enrich single RBP-mediated in situ RNA-RNA spatial interacting fragments for deep sequencing. We determine hnRNPA1- and PTBP1-mediated RNA-RNA interactions and regulatory mechanisms in HeLa cells. Unexpectedly, 3D RNA map analysis shows that PTBP1-mediated loops in introns preferably promote cassette exon splicing by accelerating asymmetric intron removal, whereas the loops spanning across cassette exon primarily repress splicing. This "positional rule" can faithfully predict PTBP1-regulated splicing outcomes. We further demonstrate that cancer-related splicing quantitative trait loci can disrupt RNA loops by reducing PTBP1 binding on pre-mRNAs to cause aberrant splicing in tumors. Our study presents a powerful method for exploring the functions of RBP-mediated RNA-RNA interactions in gene regulation and disease.

molecular biology↗

Computational Design of Two New Vitamin K Epoxide Reductase Inhibitors

Vitamin K epoxide reductase (VKOR) inhibitors are commonly used to treat atrial fibrillation and ischemic stroke. However, due to the side effects and poor absorbance of existing drugs, there is urgent need for developing better VKOR inhibitor drugs. In this work, computational bioisosteric replacement and chemical intuition were used to design two novel VKOR inhibitors. The new candidates are predicted to have improved ADMET and binding properties compared to existing drugs.

biochemistry↗

Single cell Transcriptome and T cell Repertoire Mapping of the Mechanistic Signatures and T cell Trajectories Contributing to Vascular and Dermal Manifestations of Behcet Disease

Behcets disease (BD) is a form of vasculitis characterized by complex multi-organ manifestations that may frequently recur and induce major tissue damage. Although genetic association studies have identified a number of risk factors, the etiology of BD and its tissue manifestations remains unknown, and the landscape of immune responses in BD is opaque, particularly in terms of inflammatory recurrence. In this study, we mapped the transcriptomes of the immune cell compartment in BD at single-cell resolution, sampling both circulation and affected skin in order to chart the immune interplay driving pathogenesis. Through comprehensive expression and communication analysis of the twenty major cell types identified, we observe striking mechanistic differences in immune response between BD skin lesions and peripheral circulation involving TNF signaling and T cell migration. Through integrated TCR sequencing, we further discover a pattern of clonal sharing between circulating and skin CD8+T cell populations along a trajectory defined by the acquisition of tissue-residential properties. In addition, we also identify a population of expanded CD4+ Tregs with the propensity to produce IL-32. Instead of suppressing effector T cell proliferation and function, IL-32 triggers increased expression of CD97, and may thus encourage prolonged local T cell activity in the skin. Collectively, our data serve to advance understandings of contributions of varying immune cell types to BD pathogenesis in the vasculature and skin, as well as the lifecycle patterns of T cells clones in this context. These data may also assist in further investigations of the mechanisms contributing to Treg dysfunction in systemic autoimmunity, while generating a conceptual model of T cell function contributing to BD recurrence.

immunology↗

Dynamic control of metabolic zonation and liver repair by endothelial cell Wnt2 and Wnt9b revealed by single cell spatial transcriptomics using Molecular Cartography

The conclusive identity of Wnt proteins regulating liver zonation (LZ) and regeneration (LR) remains unclear despite an undisputed role of {beta}-catenin. Using single-cell analysis of liver cells from various species, a conserved Wnt2 and Wnt9b expression in endothelial cells (ECs) in zone 3 shown to be the major Wnt cell source, was identified. Conditional EC-elimination of Wnt2 and Wnt9b led to perturbation of LZ with not only loss of {beta}-catenin targets in zone 3, but also re-appearance of zone 1 genes in zone 3, unraveling dynamicity as revealed by single-cell spatial transcriptomics using Molecular Cartography. Defective LR observed in the knockouts phenocopied other models of defective hepatic Wnt signaling. Administration of a tetravalent antibody to activate Wnt signaling rescued LZ and LR in the knockouts. Molecular Cartography on the livers of the agonist-treated animal revealed changes in LZ. Administration of the agonist also promoted LR in acetaminophen overdose acute liver failure (ALF) fulfilling an unmet clinical need. Overall, we report an unequivocal role of EC-Wnt2 and Wnt9b in LZ and LR and show the role of Wnt activators as regenerative therapy for ALF.

pathology↗

cLD: Rare-variant disequilibrium between genomic regions identifies novel genomic interactions

Linkage disequilibrium (LD) is a fundamental concept in genetics; critical for studying genetic associations and molecular evolution. However, LD measurements are only reliable for common genetic variants, leaving low-frequency variants unanalyzed. In this work, we introduce cumulative LD (cLD), a stable statistic that captures the rare-variant LD between genetic regions, which reflects more biological interactions between variants, in addition to lack of recombination. We derived the theoretical variance of cLD using delta methods to demonstrate its higher stability than LD for rare variants. This property is also verified by bootstrapped simulations using real data. In application, we find cLD reveals an increased genetic association between genes in 3D chromatin interactions, a phenomenon recently reported negatively by calculating standard LD between common variants. Additionally, we show that cLD is higher between gene pairs reported in interaction databases, identifies unreported protein-protein interactions, and reveals interacting genes distinguishing case/control samples in association studies.

bioinformatics↗

The first sheep graph pan-genome reveals the spectrum of structural variations and their effects on different tail phenotypes

Structural variations (SVs) are a major contributor to genetic diversity and phenotypic variations, but their prevalence and functions in domestic animals are largely unexplored. Here, we assembled 26 haplotype-resolved genome assemblies from 13 genetically diverse sheep using PacBio HiFi sequencing. We constructed a graph-based ovine pan-genome and discovered 142,422 biallelic insertions and deletions, 7,028 divergent alleles and 13,419 multiallelic variations. We then used a graph-based approach to genotype the biallelic SVs in 684 individuals from 45 domestic breeds and two wild species. Integration with RNA-seq data allows to identify candidate expression-associated SVs. We demonstrate a direct link of SVs and phenotypes by localizing the putative causative insertion in HOXB13 gene responsible for the long-tail trait and identifying multiple large SVs associated with the fat-tail. Beyond generating a benchmark resource for ovine structural variants, our study highlights that animal genetic research will greatly benefit from using a pan-genome graph rather than a single reference genome.

genomics↗

Traditional martial arts and shooting training have different effects on auditory fine structure processing ability---Evidence from behavioral tests and fMRI

Explore the influence of traditional martial arts and shooting training on the ability of auditory temporal fine structure (TFS) processing. Twenty-five college students participated in the experiment, including 8 traditional martial arts practitioners, 8 high-level shooting athletes, and 9 control groups without any regular exercise habits. The BIC (break in interaural correlation) delay threshold and TFS1 test were used to evaluate the temporary storage capacity and sensitivity of TFS, respectively, and a fMRI test was performed after the test. The results found that the traditional martial arts group had stronger TFS sensitivity, while the shooting group had stronger TFS retention ability, and the performance of the behavioral test of the shooting group is related to the fALFF value of the brain area of interest. Traditional martial arts and shooting training have improved the ability of auditory information processing from different angles, diversified exercise habits will lead to the development of diversity in brain structure and function.

neuroscience↗

Identification of diverse viruses associated with grasshoppers unveils phylogenetic congruence between hosts and viruses

Locusts and grasshoppers are one of the most dangerous agricultural pests. Environmentally benign microbial pesticides are increasingly desirable for controlling locust outbreaks in fragile ecosystems. Here we use metagenomic sequencing to profile the rich viral communities in 34 grasshopper species and report 322 viruses, including 202 novel species. Most of the identified viruses are related to other insect viruses and some are targeted by antiviral RNAi pathway, indicating they infect grasshoppers. Some plant/fungi/vertebrate associated viruses are also abundant in our samples. Our analysis of relationships between host and virus phylogenies suggests that the composition of viromes is closely allied with host evolution, and there is significant phylogenetic relatedness between grasshoppers and viruses from Lispiviridae, Partitiviridae, Orthomyxoviridae, Virgaviridae and Flaviviridae. Overall, this study is a thorough exploration of viruses in grasshoppers and provide an essential evolutionary and ecological context for host-virus interaction in Acridoidea. Author SummaryLocusts are the most destructive migratory pest in the world and continue to cause massive damages that endanger food security and threaten millions of people in 21st century. While chemical pesticides are still heavily relied on, biological pesticides developed from natural pathogens offer a reliable, less harmful alternative for controlling locust outbreaks in fragile ecosystems. Unfortunately, little is known about natural pathogens infecting this pest. In this study, we profile the viral communities in 34 grasshopper species include some major swarming species. While we identified as many as 202 novel viral species associated with grasshoppers, some of them are of potential to be developed as biocontrol agents. Our analysis of relatedness of phylogenies of grasshoppers and associated viruses helps to shed light on the eco-evolutionary interactions between insects and viruses. This work provides a valuable dataset of both academic and applied interest.

microbiology↗

HIF1α-AS1 is a DNA:DNA:RNA triplex-forming lncRNA interacting with the HUSH complex

DNA:DNA:RNA triplexes that are formed through Hoogsteen base-pairing have been observed in vitro, but the extent to which these interactions occur in cells and how they impact cellular functions remains elusive. Using a combination of bioinformatic techniques, RNA/DNA pulldown and biophysical studies, we set out to identify functionally important DNA:DNA:RNA triplex-forming long non-coding RNAs (lncRNA) in human endothelial cells. The lncRNA HIF1-AS1 was retrieved as a top hit. Endogenous HIF1-AS1 reduced the expression of numerous genes, including EPH Receptor A2 and Adrenomedullin through DNA:DNA:RNA triplex formation by acting as an adapter for the repressive human silencing hub complex (HUSH). Moreover, the oxygen-sensitive HIF1-AS1 was down-regulated in pulmonary hypertension and loss-of-function approaches not only resulted in gene de-repression but also enhanced angiogenic capacity. As exemplified here with HIF1-AS1, DNA:DNA:RNA triplex formation is a functionally important mechanism of trans-acting gene expression control.

molecular biology↗

Inhibition of Kallikrein-related peptidases 7 restrains pancreatic tumor growth through induction of ferroptosis

Pancreatic cancer is one of the most aggressive and lethal malignancies with extremely poor prognosis, and KLK7 was considered as a potential therapeutic target. In this study, we analyzed the expression of KLK7 in TCGA and GTEx databases and found that KLK7 had a negative correlation to long-term survival rate (>1.5 years) of pancreatic cancer patients. Compound 42 is a coumarinic derivative, a suicide substrate inhibitor of KLK7, which has been proved to inhibit the proliferation of PANC-1 cells in vitro effectively in our previous study. In this study, we further investigated the inhibition ability of Compound 42 in tumor formation and development in CDX and PDX tumor models of pancreatic cancer subsequently. Besides, we studied the inhibitory mechanism of Compound 42 and the result showed that Compound 42 arrested the pancreatic cancer cell cycle in G0/G1 phase and induced ferroptosis through down-regulation of GPX4 protein level and accumulation of iron ion. Thus, these experiments demonstrate that Compound 42, suppressing pancreatic cancer in vivo, is expected to become a novel drug for pancreatic cancer treatment.

molecular biology↗

Epigenetic MRI: Noninvasive Imaging of DNA Methylation in the Brain

Both neuronal and genetic mechanisms regulate brain function. While there are excellent methods to study neuronal activity in vivo, there are no nondestructive methods to measure global gene expression in living brains. Here we present a method, epigenetic magnetic resonance imaging (eMRI), that overcomes this limitation via direct imaging of DNA methylation, a major gene expression regulator. eMRI exploits the methionine metabolic pathways for DNA methylation to label genomic DNA through 13C-enriched diets. A novel 13C magnetic resonance spectroscopic imaging method then maps the spatial distribution of labeled DNA. We validated eMRI using pigs, whose brains have stronger similarity to humans in volume and anatomy than rodents, and confirmed efficient 13C labeling of brain DNA. We also discovered strong regional differences in global DNA methylation. Just as MRI measurements of regional neuronal activity have had a transformational effect on neuroscience, we expect that the eMRI signal as a surrogate for regional gene expression will enable many new investigations into the roles of gene expression in human brain function, behavior, and disease.

bioengineering↗

PHARP: A pig haplotype reference panel for genotype imputation

Pigs not only function as a major meat source worldwide but also are commonly used as an animal model for studying human complex traits. A large haplotype reference panel has been used to facilitate efficient phasing and imputation of relatively sparse genome-wide microarray chips and low-coverage sequencing data. Using the imputed genotypes in the downstream analysis, such as GWASs, TWASs, eQTL mapping and genomic prediction (GS), is beneficial for obtaining novel findings. However, currently, there is still a lack of publicly available and high-quality pig reference panels with large sample sizes and high diversity, which greatly limits the application of genotype imputation in pigs. In response, we built the pig Haplotype Reference Panel (PHARP) database. PHARP provides a reference panel of 2,012 pig haplotypes at 34 million SNPs constructed using whole-genome sequence data from more than 49 studies of 71 pig breeds. It also provides Web-based analytical tools that allow researchers to carry out phasing and imputation consistently and efficiently. PHARP is freely accessible at http://alphaindex.zju.edu.cn/PHARP/index.php. We demonstrate its applicability for pig commercial 50K SNP arrays, by accurately imputing 2.6 billion genotypes at a concordance rate value of 0.971 in 81 Large White pigs (~ 17x sequencing coverage). We also applied our reference panel to impute the low-density SNP chip into the high-density data for three GWASs and found novel significantly associated SNPs that might be casual variants.

genomics↗

Glioblastoma remodeling of neural circuits in the human brain decreases survival

Gliomas synaptically integrate into neural circuits. Prior work has demonstrated bidirectional interactions between neurons and glioma cells, with neuronal activity driving glioma growth and gliomas increasing neuronal excitability. In this study we wanted to know how glioma induced neuronal changes influence neural circuits underlying cognition and whether these interactions influence patient survival. We use intracranial brain recordings during lexical retrieval language tasks in awake humans in addition to site specific tumor tissue biopsies and cell biology experiments. We find that gliomas remodel functional neural circuitry such that task-relevant neural responses activate tumor-infiltrated cortex, beyond cortical excitation normally recruited in the healthy brain. Site-directed biopsies from functionally connected regions within the tumor are enriched for a glioblastoma subpopulation that exhibits a distinct synaptogenic and neuronotrophic phenotype. Tumor cells from functionally connected regions secrete the synaptogenic factor thrombospondin-1, which contributes to the differential neuron-glioma interactions observed in functionally connected tumor regions compared to tumor regions with less functional connectivity. The degree of functional connectivity between glioblastoma and the normal brain negatively impacts both patient survival and language task performance. These data demonstrate that high-grade gliomas functionally remodel neural circuits in the human brain, which both promotes tumor proliferation and impairs cognition.

cancer biology↗