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Shi, X.

Publications and source records attributed to Shi, X..

At least 145 records · Page 8Linked to original sources

A data-fusion approach to identifying developmental dyslexia from multi-omics datasets

This exploratory study tested and validated the use of data fusion and machine learning techniques to probe high-throughput omics and clinical data with a goal of exploring the etiology of developmental dyslexia. Developmental dyslexia is the leading learning disability in school aged children affecting roughly 5-10% of the US population. The complex biological and neurological phenotype of this life altering disability complicates its diagnosis. Phenome, exome, and metabolome data was collected allowing us to fully explore this system from a behavioral, cellular, and molecular point of view. This study provides a proof of concept showing that data fusion and ensemble learning techniques can outperform traditional machine learning techniques when provided small and complex multi-omics and clinical datasets. Heterogenous stacking classifiers consisting of single-omic experts/models achieved an accuracy of 86%, F1 score of 0.89, and AUC value of 0.83. Ensemble methods also provided a ranked list of important features that suggests exome single nucleotide polymorphisms found in the thalamus and cerebellum could be potential biomarkers for developmental dyslexia and heavily influenced the classification of DD within our machine learning models.

bioinformatics↗

The pluripotency factor Tex10 finetunes Wnt signaling for PGC and male germline development

Testis-specific transcript 10 (Tex10) is a critical factor for pluripotent stem cell maintenance and preimplantation development. Here, we dissect its late developmental roles in primordial germ cell (PGC) specification and spermatogenesis using cellular and animal models. We discover that Tex10 binds the Wnt negative regulator genes, marked by H3K4me3, at the PGC-like cell (PGCLC) stage in restraining Wnt signaling. Depletion and overexpression of Tex10 hyperactivate and attenuate the Wnt signaling, resulting in compromised and enhanced PGCLC specification efficiency, respectively. Using the Tex10 conditional knockout mouse models combined with single-cell RNA sequencing, we further uncover critical roles of Tex10 in spermatogenesis with Tex10 loss causing reduced sperm number and motility associated with compromised round spermatid formation. Notably, defective spermatogenesis in Tex10 knockout mice correlates with aberrant Wnt signaling upregulation. Therefore, our study establishes Tex10 as a previously unappreciated player in PGC specification and male germline development by fine-tuning Wnt signaling.

developmental biology↗

DNA Polymerases in Precise and Predictable CRISPR/Cas9-mediated Chromosomal Rearrangements

Recent studies have shown that Cas9-mediated CRISPR gene editing outcomes at junctions of chromosomal rearrangements are precise and predictable; however, the underlying mechanisms are poorly understood due to lack of suitable assay system and analysis tool. Here we developed a customized computer program to take account of staggered Cas9 cleavage and to rapidly process large volumes of junctional sequencing reads from chromosomal rearrangements, including DNA-fragment inversions, duplications, and deletions. We also established a sensitive assay system using HPRT1 and DCK as reporters for cell growth during DNA-fragment editing by Cas9 with dual sgRNAs and found prominent large resections at junctions of chromosomal rearrangements. In addition, we found that knockdown of PolQ (encoding Pol{theta}) results in increased large resections but decreased small deletions. We also found that the mechanisms for generating small deletions of 1bp and >1bp during DNA-fragment editing are different with regards to their opposite dependencies on Pol{theta} and Pol{lambda}. Specifically, Pol{theta} suppresses 1bp deletions but promotes >1bp deletions, whereas Pol{lambda} promotes 1bp deletions but suppresses >1bp deletions. Finally, we found that Pol{lambda} is the main DNA polymerase responsible for fill-in of the 5 overhangs of staggered Cas9 cleavage ends. These findings contribute to our understanding of the molecular mechanisms of CRISPR/Cas9-mediated DNA-fragment editing and have important implications for controllable, precise, and predictable gene editing.

molecular biology↗

Probabilistic cell/domain-type assignment of spatial transcriptomics data with SpatialAnno

In the analysis of both single-cell RNA sequencing (scRNA-seq) and spatially resolved transcriptomics (SRT) data, classifying cells/spots into cell/domain types is an essential analytic step for many secondary analyses. Most of the existing annotation methods have been developed for scRNA-seq datasets without any consideration of spatial information. Here, we present SpatialAnno, an efficient and accurate annotation method for spatial transcriptomics datasets, with the capability to effectively leverage a large number of non-marker genes as well as "qualitative" information about marker genes without using a reference dataset. Uniquely, SpatialAnno estimates low-dimensional embeddings for a large number of non-marker genes via a factor model while promoting spatial smoothness among neighboring spots via a Potts model. Using both simulated and four real spatial transcriptomics datasets from the 10x Visium, ST, Slide-seqV1/2, and seqFISH platforms, we showcase the methods improved spatial annotation accuracy, including its robustness to the inclusion of marker genes for irrelevant cell/domain types and to various degrees of marker gene misspecification. SpatialAnno is computationally scalable and applicable to SRT datasets from different platforms. Furthermore, the estimated embeddings for cellular biological effects facilitate many downstream analyses.

bioinformatics↗

RTCpredictor: Identification of Read-Through Chimeric RNAs from RNA Sequencing Data

Read-through chimeric RNAs are gaining attention in cancer and other research fields, yet current tools often fail in predicting them. We have thus developed the first read-through chimeric RNA specific prediction method, RTCpredictor, utilizing a fast ripgrep algorithm to search for all possible exon-exon combinations of parental gene pairs. Compared with other ten popular tools, RTCpredictor achieved top performance on both simulated and real datasets. We randomly selected up to 30 candidate read-through chimeras predicted from each software method and experimentally validated a total of 109 read-throughs and on this set, RTCpredictor outperformed all the other methods. In addition, RTCpredictor (https://github.com/sandybioteck/RTCpredictor) has less memory requirements and faster execution time.

genomics↗

TERT accelerates BRAF mutant-induced thyroid cancer dedifferentiation and progression by regulating ribosome biogenesis

TERT reactivation occurs frequently in human malignancies. While BRAF activating mutation widely existed in cancers at various stages, TERT reactivation mainly occurs in advanced tumors. However, in vivo evidence for TERT role in cancer progression and the underlying mechanism is currently lacking. In this study, we induced TERT and/or BRAF V600E expression in mouse thyroid epithelium. TERT overexpression alone had no evident effect on tumor initiation. BRAFVE expression itself induced mediocre papillary thyroid cancer (PTC). Notably, the co-expression of BRAFVE and TERT resulted in aggressive poorly differentiated thyroid carcinoma (PDTC). Spatial transcriptome revealed that tumors from co-mutant mice were highly heterogeneous and dedifferentiation process significantly correlated with ribosomal pathways. Mechanistically, TERT boosted ribosomal RNA expression and protein synthesis. CX-5461, a rRNA transcription inhibitor, effectively blocked proliferation and induced redifferentiation. Thus, TERT promotes thyroid cancer progression by inducing dedifferentiation, and ribosome biogenesis inhibition represents a potential treatment strategy for TERT-reactivated cancers. Highlights[tpltrtarr] TERT accelerated thyroid cancer dedifferentiation and metastasis in vivo [tpltrtarr]TERT regulated rRNA metabolism and MTORC1/ S6K/RPS6 activities [tpltrtarr]CX-5461 inhibited the progression of TERT-reactivated melanoma and thyroid cancer [tpltrtarr]Inhibition of rRNA induced redifferentiation of advanced thyroid cancer with TERT activation

cancer biology↗

A simple, flexible and high-efficiency western blot analysis for age-related human induced neurons

High-throughput western blot (WB) analysis of small and precious samples, such as various age-related subtype-specific human induced neurons (hiNs), confers the ability to obtain more consistent, comparable, and informative data from materials with extremely limited availability. In this study, p-toluenesulphonic acid (PTSA), an odorless tissue fixative, was used to inactivate HRP for developing a high-throughput WB method. PTSA-treated blots showed fast and efficient inactivation of HRP without detectable protein loss and epitope damage. With a brief PTSA-treatment before every next probing, 10 proteins of dopaminergic hiNs could be sequentially, sensitively, and specifically detected in a blot. These WB data proved the age-associated and neuron-specific features of hiNs and further revealed a sharp reduction of two Parkinsons disease-associated proteins, UCHL1 and GAP43, in the normal aging dopaminergic neurons. Together, this study developed a unique and high-efficiency WB analysis and pinpointed its special value for capturing robust useful data from limited, precious samples. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/526150v2_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@18fcd9dorg.highwire.dtl.DTLVardef@42426org.highwire.dtl.DTLVardef@1e13accorg.highwire.dtl.DTLVardef@1db2f39_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTS{checkmark} P-toluenesulphonic acid (PTSA) quickly and fully deactivated HRP on immunoblots. {checkmark}PTSA was an odorless, non-volatile, low cost, and user-friendly HRP inactivator. {checkmark}PTSA allowed high-efficiency WB analysis to save small precious samples and time. {checkmark}10 proteins were detected in a single blot of age-relevant human induced neurons. {checkmark}UCHL1 and GAP43 sharp decline occurred in aging human induced dopaminergic neurons.

biochemistry↗

Large polyacrylamide hydrogels for large-batch cell culture and mechanobiological studies

The rigidity of a cells substrate or extracellular matrix plays a vital role in regulating cell and tissue functions. Polyacrylamide (PAAm) hydrogels are one of the most widely used cell culture substrates that provide a physiologically relevant range of stiffness. However, it is still arduous and time-consuming to prepare PAAm substrates in large batches for high-yield or multi-scale cell cultures. Here we present a simple method to prepare PAAm hydrogels with less time cost and easily accessible materials. The hydrogel is mechanically uniform and supports cell culture in a large batch. We further show that the stiffness of the hydrogel covers a large range of Youngs modulus and is sensed by cells, regulating various cell features including changes in cell morphology, proliferation, and contractility. This method improves reproducibility of mechanobiology studies and can be easily applied for mechanobiology research requiring large numbers of cells or experimental groups.

bioengineering↗

Engineering synthetic CopT/A-based genetic circuits for miRNA imaging and functional gene regulation

Synthetic genetic circuits that can operate at the transcriptional and translation levels have been widely applied in the control of cellular behaviors and functions. However, the regulation of genetic circuits is often accompanied by the introduction of exogenous substances or the endogenous generation of inhibitory products, which would bring uncontrollable hazards for biological safety and reduce the efficiency of the system. Here, we described a miRNA-responsive CopT-CopA (miCop) genetic circuit system to realize real-time monitoring the intracellular expression of miRNA-124a during neurogenesis or miRNA-122 under the stimulation of extracellular drugs in living cells and animals. Furthermore, to prove the modularity of the system, we engineered this mipCop to tune the expression of DTA (diphtheria toxin A) gene, and showed the powerful capacity of killing cancer cells by inducing apoptosis and cell cycle arrest based on miRNA response. This study provides an effective means to couple miRNA sensing with miRNA-responsive gene modulation, which may open up new diagnostic or therapeutic applications.

synthetic biology↗

Secure Deep Learning on Genomics Data via a Homomorphic Encrypted Residue Activation Network

Growing applications of deep learning on sensitive genomics and biomedical data introduce challenging privacy and secure problems. Homomorphic encryption (HE) is one of appropriate cryptographic techniques to provide secure machine learning evaluation by directly computing over encrypted data, so that allows the data owner and model owner to outsource processing of sensitive data to an untrusted server without leaking any information about the data. However, most current HE schemes only support limited arithmetic operations, which significantly hinder their applications to support secure deep learning algorithm. Considering the potential performance loss introduced for approximating activation function, in this paper, we develop a novel HE friendly deep network, named Residue Activation Network (ResActNet) to implement precise privacy-preserving machine learning algorithm with a non-approximating activation on HE scheme. We considered a residue activation strategy with a scaled power activation function in the deep network. In particular, a scaled power activation (SPA) function is set within the HE scheme, and so that can be directly deployed on HE computation. Moreover, we proposed a residue activation strategy to constrain the latent space in the training process for alleviating the optimization difficulty. We comprehensively evaluate ResActNet using diverse genomics datasets and widely-used image datasets. Our results demonstrate that ResActNet outperforms other alternative solutions to secure machine learning with HE and achieves low approximation errors in classification and regression tasks.

bioinformatics↗

FedDP: Secure Federated Learning for Disease Prediction with Imbalanced Genetic Data

It is challenging to share and aggregate biomedical data distributed among multiple institutions or computing resources due to various concerns including data privacy, security, and confidentiality. The federated Learning (FL) schema can effectively enable multiple institutions jointly perform machine learning by training a robust model with local data to satisfy the requirement of user privacy protection as well as data security. However, conventional FL methods are exposed to the risk of gradient leakage and cannot be directly applied to genetic data since they cannot address the unique challenges of data imbalance typically seen in genomics. To provide secure and efficient disease prediction based on genetic data distributed across multiple parties, we propose an FL framework enhanced with differential privacy (FedDP) on trained model parameters. In FedDP, local models can be trained among multiple local-hold genetic data with efficient secure and privacy-preserving techniques. The key idea of FedDP is to deploy differential privacy on compressed intermediate gradients that are computed and transmitted by optimizers from local parties. In addition, the unique weighted minmax loss in FedDP is able to address the difficulties of prediction for highly imbalanced genetic datasets. Our experiments on multiple genetic datasets demonstrate that FedDP provides a powerful tool to implement and evaluate various strategies in support of privacy preservation and model performance guarantee to overcome data imbalance.

bioinformatics↗

In situ structures of secretins from bacterial type II secretion system reveal their membrane interactions and translocation process

The GspD secretin is the outer membrane channel of the bacterial type II secretion system (T2SS) which secrets diverse effector proteins or toxins that cause severe diseases such as diarrhea and cholera. GspD needs to translocate from the inner to the outer membrane to exert its function, and this process is an essential step for T2SS to assemble. Here, we investigate two types of secretins discovered so far in Escherichia coli, GspD and GspD{beta}, respectively. By electron cryotomography subtomogram averaging, we determine in situ structures of all the key intermediate states of GspD and GspD{beta} in the translocation process, with resolution ranging from 9 [A] to 19 [A]. In our results, GspD and GspD{beta} present entirely different membrane interaction patterns and ways of going across the peptidoglycan layer. We propose two distinct models for the membrane translocation of GspD and GspD{beta}, providing a comprehensive perspective on the inner to outer membrane biogenesis of T2SS secretins.

microbiology↗

Soft multimodal opto-electric biointerfaces for co-localized optical and electrical recording of cell function

Optical fluorescence and electrical monitoring of cell activity are two powerful approaches to study organ functions. Simultaneous recording of optical and electrical data types will provide complementary information from and take advantage of each approach. However, devices that can concurrently record optical signals from the same cell population underneath the microelectrodes have not been widely explored and remain a grand technical challenge. This work presents an innovative flexible opto-electric device that monolithically integrates transparent gold nanogrid microelectrodes directly above microscale light-emitting diodes, photodetectors, and optical filters to achieve co-localized crosstalk-free optical fluorescence and electrical recording. The optimized gold nanogrid microelectrodes show excellent optical transparency (>81%) and low normalized 1 kHz electrochemical impedance (6.3 {Omega} cm2). The optical recording subsystem offers high wavelength selectivity (>1,300) and linearity (R2 >0.99) for exciting and capturing green fluorescence from various fluorescent reporters in measurement ranges relevant to in vivo applications with minimal thermal effects. The opto-electric device exhibits remarkable durability under soaking for 40 days and repetitive mechanical bending for 5,000 cycles. The work may provide a versatile approach for constructing mechanically compliant biointerfaces containing crosstalk-free optical and electrical modalities with widespread application potentials in basic and clinical research.

bioengineering↗

novoRNABreak: local assembly for novel splice junction and fusion transcript detection from RNA-seq data

We present novoRNABreak, a unified framework for cancer specific novel splice junction and fusion transcript detection in RNA-seq data obtained from human cancer samples. novoRNABreak is based on a local assembly model, which offers a tradeoff between the alignment-based and de novo whole transcriptome assembly (WTA) approaches, namely, being more sensitive in assembling novel junctions that cannot be directly aligned, and more efficient due to the strategy that focuses on junctions rather than full-length transcripts. The performance of novoRNABreak is demonstrated by a comprehensive set of experiments using synthetic data generated based on genome reference, as well as real RNA-seq data from breast cancer and prostate cancer samples. The results show that novoRNABreak can detect novel splice junctions and fusion transcripts efficiently with high sensitivity and reasonable specificity.

bioinformatics↗

Characterization of a novel botybirnavirus with a unique dsRNA infecting Didymella theifolia from tea plants

Didymella theifolia specifically infects some local varieties of Camellia sinensis in China, representing a unique fungal species, and characterization of the mycoviruses related to this fungal species is attractive. Three double-stranded RNAs (dsRNAs; dsRNAs 1, 2 and 3 with sizes of 6338, 5910 and 727 bp, respectively) were identified in an avirulent strain CJP4-1 of D. theifolia exhibiting normal growth and morphologies. Characterization of the dsRNAs 1 and 2 revealed that they are genomic components of a novel botybirnavirus, tentatively named Didymella theifolia botybirnavirus 1 (DtBRV1), and encapsidated in isometric virions with a size of [~]39.8 nm in diameter. It is worth noting that dsRNA3 shares no detectable identity with those sequences deposited in NCBI database, while a high identity (36.58% and 40.93%) with the left regions of dsRNAs 1 and 2, but is not encapsidated in DtBRV1 particles, suggesting it is a unique dsRNA unit that is not a DtBRV1 component or a satellite and its taxonomic classification remains unclear. SDS-polyacrylamide gel electrophoresis in combination with peptide mass fingerprint analysis revealed that DtBRV1 capsid protein consisting of polypeptides encoded by the left regions of both genomic components. DtBRV1 is efficiently vertically transmitted through conidia while difficult in horizontal transmission from strain CJP4-1 to other strains. DtBRV1 has no effects on fungal growth and virulence as accessed with the transfectants of virulent strain JYC1-6 of D. theifolia infected by DtBRV1. DtBRV1 with specific molecular traits contributes useful information for a better understanding of the mycoviral community. ImportanceTea plants represent an ancient and unique plant species community cultured in China, while the mycoviruses related to the phytopathogenetic fungi infecting tea remain limited. Here, we characterized a novel botybirnavirus (tentatively named Didymella theifolia botybirnavirus1 (DtBRV1), and a specific dsRNA infecting Didymella theifolia responsible for a noticeable disease of tea plants. DtBRV1 contains two dsRNAs (1 and 2) encapsidated in isometric virions in size of [~]39.8 nm, while dsRNA3 is not encapsidated in the viral particles although it has a high identity with the mycoviral genomic components. Additionally, DtBRV1 coat proteins are composed of fused proteins encoded by both dsRNA-coding open reading frames most likely after cleave and fuse processing progress, which is striking unlike most mycoviruses. With some specific molecular traits, DtBRV1 and the related specific dsRNA unit expand our understanding of virus diversity, taxonomy, and evolution.

microbiology↗

Assembly of 43 diverse human Y chromosomes reveals extensive complexity and variation

The prevalence of highly repetitive sequences within the human Y chromosome has led to its incomplete assembly and systematic omission from genomic analyses. Here, we present long-read de novo assemblies of 43 diverse Y chromosomes spanning 180,000 years of human evolution, including two from deep-rooted African Y lineages, and report remarkable complexity and diversity in chromosome size and structure, in contrast with its low level of base substitution variation. The size of the Y chromosome assemblies varies extensively from 45.2 to 84.9 Mbp and include, on average, 81 kbp of novel sequence per Y chromosome. Half of the male-specific euchromatic region is subject to large inversions with a >2-fold higher recurrence rate compared to inversions in the rest of the human genome. Ampliconic sequences associated with these inversions further show differing mutation rates that are sequence context-dependent and some ampliconic genes show evidence for concerted evolution with the acquisition and purging of lineage-specific pseudogenes. The largest heterochromatic region in the human genome, the Yq12, is composed of alternating arrays of DYZ1 and DYZ2 repeat units that show extensive variation in the number, size and distribution of these arrays, but retain a 1:1 copy number ratio of the monomer repeats, consistent with the notion that functional or evolutionary forces are acting on this chromosomal region. Finally, our data suggests that the boundary between the recombining pseudoautosomal region 1 and the non-recombining portions of the X and Y chromosomes lies 500 kbp distal to the currently established boundary. The availability of sequence-resolved Y chromosomes from multiple individuals provides a unique opportunity for identifying new associations of specific traits with Y-chromosomal variants and garnering novel insights into the evolution and function of complex regions of the human genome.

genomics↗

Extracellular vimentin is sufficient to promote cell attachment, spreading, and motility by a mechanism involving N-acetyl glucosamine-containing structures

Vimentin intermediate filaments form part of the cytoskeleton of mesenchymal cells, but under pathological conditions often associated with inflammation, vimentin filaments depolymerize as the result of phosphorylation or citrullination, and vimentin oligomers are secreted or released into the extracellular environment. In the extracellular space, vimentin can bind surfaces of other cells and the extracellular matrix, and the interaction between extracellular vimentin and other cell types can trigger changes in cellular functions, such as activation of fibroblasts to a fibrotic phenotype. The mechanism by which extracellular vimentin binds external cell membranes and whether vimentin alone can act as an adhesive anchor for cells is largely uncharacterized. Here, we show that various cell types (normal and vimentin null fibroblasts, mesenchymal stem cells, A549 lung carcinoma cells) attach to and spread on polyacrylamide hydrogel substrates covalently linked to vimentin. Using traction force microscopy and spheroid expansion assays, we characterize how different cell types respond to extracellular vimentin. Cell attachment to and spreading on vimentin-coated surfaces is inhibited by hyaluronic acid (HA) degrading enzymes, HA synthase inhibitors, soluble heparin, or N-acetyl glucosamine, treatments that have little or no effect on the same cell types binding to collagen-coated hydrogels. These studies highlight the effectiveness of substrate-bound vimentin as a ligand for cells and suggest that carbohydrate structures, including the glycocalyx and glycosylated cell surface proteins that contain N-acetyl glucosamine, form a novel class of adhesion receptors for extracellular vimentin.

biophysics↗

Transparent and stretchable metal nanowire composite recording microelectrode arrays

Transparent microelectrodes have received much attention from the biomedical community due to their unique advantages in concurrent crosstalk-free electrical and optical interrogation of cell/tissue activity. Despite recent progress in constructing transparent microelectrodes, a major challenge is to simultaneously achieve desirable mechanical stretchability, optical transparency, electrochemical performance, and chemical stability for high-fidelity, conformal, and stable interfacing with soft tissue/organ systems. To address this challenge, we have designed microelectrode arrays (MEAs) with gold coated silver nanowires (Au-Ag NWs) by combining technical advances in materials, fabrication, and mechanics. The Au coating improves both the chemical stability and electrochemical impedance of the Au-Ag NWs microelectrodes with only slight changes in optical properties. The MEAs exhibit a high optical transparency >80% at 550 nm, a low normalized 1 kHz electrochemical impedance of 1.2-7.5 {Omega} cm2, stable chemical and electromechanical performance after exposure to oxygen plasma for 5 minutes and cyclic stretching for 600 cycles at 20% strain, superior to other transparent microelectrode alternatives. The MEAs easily conform to curvilinear heart surfaces for co-localized electrophysiological and optical mapping of cardiac function. This work demonstrates that stretchable transparent metal nanowire MEAs are promising candidates for diverse biomedical science and engineering applications, particularly under mechanically dynamic conditions.

bioengineering↗