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Zhang, L.

Publications and source records attributed to Zhang, L..

At least 757 records · Page 42Linked to original sources

TRAFICA: Improving Transcription Factor Binding Affinity Prediction using Large Language Model on ATAC-seq Data

AO_SCPLOWBSTRACTC_SCPLOWIn silico transcription factor and DNA (TF-DNA) binding affinity prediction plays a vital role in examining TF binding preferences and understanding gene regulation. The existing tools employ TF-DNA binding profiles from in vitro high-throughput technologies to predict TF-DNA binding affinity. However, TFs tend to bind to sequences in open chromatin regions in vivo, such TF binding preference is seldomly considered by these existing tools. In this study, we developed TRAFICA, an open chromatin language model to predict TF-DNA binding affinity by integrating the characteristics of sequences from open chromatin regions in ATAC-seq experiments and in vitro TF-DNA binding profiles from high-throughput technologies. We applied self-supervised learning to pre-train TRAFICA on over 13 million nucleotide sequences from the peaks in ATAC-seq experiments to learn the TF binding preference in vivo. TRAFICA was further fine-tuned using the TF-DNA binding profiles from PBM and HT-SELEX technologies to learn the association between TFs and their target DNA sequences. We observed that TRAFICA significantly outperformed both machine learning-based and deep learning-based tools in predicting in vitro and in vivo TF-DNA binding affinity. These findings indicate that considering the characteristics of sequences from open chromatin regions could significantly improve TF-DNA binding affinity prediction, particularly when limited TF-DNA binding profiles from high-throughput technologies are available for specific TFs.

bioinformatics↗

Deep Reinforcement Learning Enables Better Bias Control in Benchmark for Virtual Screening

Virtual screening (VS) has been incorporated into the paradigm of modern drug discovery. This field is now undergoing a new wave of revolution driven by artificial intelligence and more specifically, machine learning (ML). In terms of those out-of-the- box datasets for model training or benchmarking, their data volume and applicability domain are limited. They are suffering from the biases constantly reported in the ML application. To address these issues, we present a novel benchmark named MUBDsyn. The utilization of synthetic decoys (i.e., presumed inactives) is the main feature of MUBDsyn, where deep reinforcement learning was leveraged for bias control during decoy generation. Then, we carried out extensive validations on this new benchmark. First, we confirmed that MUBDsyn was superior to the classical benchmarks in control of domain bias, artificial enrichment bias and analogue bias. Moreover, we found that the assessment of ML models based on MUBDsyn was less biased as revealed by the analysis of asymmetric validation embedding bias. In addition, MUBDsyn showed better setting of benchmarking challenge for deep learning models compared with NRLiSt- BDB. Overall, we have proven that MUBDsyn is the close-to-ideal benchmark for VS. The computational tool is publicly available for the easy extension of MUBDsyn.

bioinformatics↗

Polycomb protein binding and looping mediated by Polycomb Response Elements in the ON transcriptional state

Polycomb group proteins (PcG) mediate epigenetic silencing of important developmental genes and other targets. In Drosophila, canonical PcG-target genes contain Polycomb Response Elements (PREs) that recruit PcG protein complexes including PRC2 that tri- methylates H3K27 forming large H3K27me3 domains. In the OFF transcriptional state, PREs loop with each other and this looping strengthens silencing. Here we address the question of what PcG proteins bind to PREs when canonical PcG target genes are expressed, and whether PREs loop when these genes are ON. Our data show that the answer to this question is PRE-specific but general conclusions can be made. First, within a PcG-target gene, some regulatory DNA can remain covered with H3K27me3 and PcG proteins remain bound to PREs in these regions. Second, when PREs are within H3K27ac domains, PcG- binding decreases, however, this depends on the protein and PRE. The DNA binding protein GAF, and the PcG protein Ph remain at PREs even when other PcG proteins are greatly depleted. In the ON state, PREs can still loop with each other, but also form loops with presumptive enhancers. These data support the model that, in addition to their role in PcG silencing, PREs can act as "promoter-tethering elements" mediating interactions between promoter proximal PREs and distant enhancers.

genetics↗

Resistance mechanisms of SARS-CoV-2 3CLpro to the non-covalent inhibitor WU-04

Drug resistance poses a significant challenge in the development of effective therapies against SARS-CoV-2. Here, we identified two double mutations, M49K/M165V and M49K/S301P, in the 3C-like protease (3CLpro) that confer resistance to a novel non-covalent inhibitor, WU-04. Crystallographic analysis indicates that the M49K mutation destabilizes the WU-04 binding pocket, impacting the binding of WU-04 more significantly than the binding of 3CLpro substrates. The M165V mutation directly interferes with WU-04 binding. The S301P mutation, which is far from the WU-04 binding pocket, indirectly affects WU-04 binding by restricting the rotation of 3CLpros C-terminal tail and impeding 3CLpro dimerization. We further explored 3CLpro mutations that confer resistance to two clinically used inhibitors: ensitrelvir and nirmatrelvir, and revealed a trade-off between the catalytic activity, thermostability, and drug resistance of 3CLpro. We found that mutations at the same residue (M49) can have distinct effects on the 3CLpro inhibitors, highlighting the importance of developing multiple antiviral agents with different skeletons for fighting SARS-CoV-2. These findings enhance our understanding of SARS-CoV-2 resistance mechanisms and inform the development of effective therapeutics.

microbiology↗

Attenuating amyloid-beta pathology in mice with in situ programmed astrocytes

Astrocytes are abundant cells in the central nervous system that provide trophic support for neurons and clear detrimental factors, such as A{beta} oligomers (A{beta}Os). However, in the brains of Alzheimers disease (AD) patients, astrocytes lose these physiological functions. Here, we genetically engineered astrocytes with an anti-A{beta}O chimeric antigen receptor (CAR), constructed by replacing the antigen-binding domain of MerTK with an A{beta}O-specific single-chain variable fragment, to direct their phagocytic activity against A{beta}Os. CAR-engineered astrocytes (CAR-As) showed significantly enhanced phagocytosis of A{beta}Os due to effective activation of Rac1, Cdc42 and RhoA and markedly decreased release of pro-inflammatory cytokines due to inhibition of the NF-{kappa}B and cytokine receptor signalling pathways. Consistently, in situ CAR-As markedly ameliorated the cognitive deficits of APP/PS1 transgenic mice possibly by clearing A{beta}Os and creating a non-inflammatory microenvironment for neuronal survival and the restoration of microglia to a healthy phenotype. Our present study is the first to introduce a CAR-A-based therapy, validate its feasibility and effectiveness, and highlight its potential application for the treatment of AD and other brain disorders.

neuroscience↗

Nucleolus and centromere TSA-Seq reveals variable localization of heterochromatin in different cell types

Genome differential positioning within interphase nuclei remains poorly explored. We extended and validated TSA-seq to map genomic regions near nucleoli and pericentric heterochromatin in four human cell lines. Our study confirmed that smaller chromosomes localize closer to nucleoli but further deconvolved this by revealing a preference for chromosome arms below 36-46 Mbp in length. We identified two lamina associated domain subsets through their differential nuclear lamina versus nucleolar positioning in different cell lines which showed distinctive patterns of DNA replication timing and gene expression across all cell lines. Unexpectedly, active, nuclear speckle-associated genomic regions were found near typically repressive nuclear compartments, which is attributable to the close proximity of nuclear speckles and nucleoli in some cell types, and association of centromeres with nuclear speckles in hESCs. Our study points to a more complex and variable nuclear genome organization than suggested by current models, as revealed by our TSA-seq methodology.

cell biology↗

The effect of problem-based learning on improving problem-solving, self-directed learning, and critical thinking ability for the pharmacy students

ObjectiveThis study aimed to comprehensively evaluate the effect of PBL on problem-solving, self-directed learning, and critical thinking ability of pharmaceutical students through a randomized controlled trial (RCT) and meta-analysis of RCTs. MethodsIn 2021, 57 third-year pharmacy students from China Pharmaceutical University were randomly divided into a PBL group and a lecture-based learning (LBL) group. Mean scores were compared between the two groups for problem-solving, self-directed learning, communication skills, critical thinking, and final exam grades. Students feedback on the implementation of PBL was also collected. A meta-analysis was subsequently performed on eight studies involving 1,819 students. ResultsThe PBL group had significantly higher mean scores for problem-solving (8.43{+/-}1.56) and self-directed learning (7.39{+/-}1.19) than the LBL group (7.02{+/-}1.72 and 6.41{+/-}1.28, respectively). The PBL group also showed better communication skills (8.86{+/-}1.47) than the LBL group (7.68{+/-}1.89). The mean level of critical thinking was significantly higher in the PBL group than the LBL group (p=0.02). The PBL group also had better final exam grades (79.86{+/-}1.38) compared to the LBL group (68.1{+/-}1.76). Student feedback on PBL implementation was positive. The subsequent meta-analysis confirmed these findings. ConclusionThis study found that PBL is an effective teaching method for pharmacy students.

scientific communication and education↗

Kairos infers in situ horizontal gene transfer in longitudinally sampled microbiomes through microdiversity-aware sequence analysis

Horizontal gene transfer (HGT) occurring within microbiomes is linked to complex environmental and ecological dynamics that are challenging to replicate in controlled settings. Consequently, most extant studies of microbiome HGT are either simplistic experimental settings with tenuous relevance to real microbiomes or correlative studies that assume that HGT potential is a function of the relative abundance of mobile genetic elements (MGEs), the vehicles of HGT. Here we introduce Kairos as a bioinformatic tool deployed in nextflow for detecting HGT events "in situ," i.e., within a microbiome, through analysis of time-series metagenomic sequencing data. The in-situ framework proposed here leverages available metagenomic data from a longitudinally sampled microbiome to assess whether the chronological occurrence of potential donors, recipients, and putatively transferred regions could plausibly have arisen due to HGT over a range of defined time periods. The centerpiece of the Kairos workflow is a novel competitive read alignment method that enables discernment of even very similar genomic sequences, such as those produced by MGE-associated recombination. A key advantage of Kairos is its reliance on assemblies rather than metagenome assembled genomes (MAGs), which avoids systematic exclusion of accessory genes associated with the binning process. In an example test-case of real world data, use of assemblies directly produced a 264-fold increase in the number of antibiotic resistance genes included in the analysis of HGT compared to analysis of MAGs with MetaCHIP. Further, in silico evaluation of contig taxonomy was performed to assess the accuracy of classification for both chromosomally- and MGE-derived sequences, indicating a high degree of accuracy even for conjugative plasmids up to the level of class or order. Thus, Kairos enables the analysis of very recent HGT events, making it suitable for studying rapid prokaryotic adaptation in environmental systems without disturbing the ornate ecological dynamics associated with microbiomes. Current versions of the Kairos workflow are available here: https://github.com/clb21565/kairos.

bioinformatics↗

Endothelial Cell Serum and Glucocorticoid Regulated Kinase 1 (SGK1) Mediates Vascular Stiffening

BackgroundExcess dietary salt increases vascular stiffness in humans, especially in salt- sensitive populations. While we recently suggested that the endothelial sodium channel (EnNaC) contributes to salt-sensitivity related endothelial cell (EC) and arterial stiffening, mechanistic understanding is incomplete. This study thus aimed to explore the role of EC-serum and glucocorticoid regulated kinase 1 (SGK1), as a regulator of sodium channels, in EC and arterial stiffening. Methods and ResultsA mouse model of salt sensitivity-associated vascular stiffening was produced by subcutaneous implantation of slow-release deoxycorticosterone acetate (DOCA) pellets, with salt (1% NaCl, 0.2% KCl) administered via drinking water. Preliminary data showed that global SGK1 deletion caused significantly decreased blood pressure, EnNaC activity and aortic endothelium stiffness as compared to control mice following DOCA-salt treatment. To probe EC signaling pathways, selective deletion of EC-SGK1 was performed by cross-breeding cadherin 5-Cre mice with sgk1flox/flox mice. DOCA-salt treated control mice had significantly increased blood pressure, EC and aortic stiffness in vivo and ex vivo, which were attenuated by EC-SGK1 deficiency. To demonstrate relevance to humans, human aortic ECs were cultured in the absence or presence of aldosterone and high salt with or without the SGK1 inhibitor, EMD638683 (10uM or 25uM). Treatment with aldosterone and high salt increased intrinsic stiffness of ECs, which was prevented by SGK1 inhibition. Further, the SGK1 inhibitor prevented aldosterone and high salt induced actin polymerization, a key mechanism in cellular stiffening. ConclusionEC-SGK1 mediates salt-sensitivity related EC and aortic stiffening by mechanisms appearing to involve regulation actin polymerization. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/563167v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@74497forg.highwire.dtl.DTLVardef@855709org.highwire.dtl.DTLVardef@151c72org.highwire.dtl.DTLVardef@1feae92_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

In vivo affinity maturation of murine B cells reprogrammed to express human antibodies

CRISPR-edited murine B cells engineered to express human antibody variable chains proliferate, class switch, and secrete these antibodies in vaccinated mice. However, current strategies disrupt the heavy-chain locus, resulting in inefficient somatic hypermutation without functional affinity maturation. Here we show that recombined murine heavy- and kappa-variable genes can be directly and simultaneously overwritten, using Cas12a-mediated cuts at their 3-most J segments and 5 homology arms complementary to distal V segments. Cells edited in this way to express the HIV-1 broadly neutralizing antibodies 10-1074 or VRC26.25-y robustly hypermutated and generated potent neutralizing plasma in vaccinated recipient mice. 10-1074 variants isolated from these mice bound and neutralized HIV-1 envelope glycoprotein more efficiently than wild-type 10-1074 while maintaining or improving its already low polyreactivity and long in vivo half-life. We further validated this approach by generating substantially broader and more potent variants of the anti-SARS-CoV-2 antibodies ZCB11 and S309. Thus, B cells edited at their native loci affinity mature, facilitating development of broad, potent, and bioavailable antibodies and expanding the potential applications of engineered B cells.

bioengineering↗

High-throughput and in-depth analysis of plasma proteome by UV-assisted protein digestion, 5-plex labeling and MS-based high abundance protein removal method

Human plasma contains various proteins, some of which reflect individuals physiological health state or predict diseases. Therefore, plasma analysis can provide a wealth of information on novel biomarkers for clinical diagnosis and prognosis. The use of mass spectrometry (MS) for high-throughput and in-depth quantitative proteomic analysis of plasma allows for highly specific and quantitative readout, but is challenging because of the high dynamic range of protein abundances. Here, we introduce a robust, high-throughput, and in-depth workflow for plasma proteome analysis based on UV-assisted rapid protein digestion, 5-plex dimethyl labeling, and MS-based high abundance protein removal. UV-assisted protein digestion could quantify the same protein numbers as traditional enzymatic hydrolysis and achieve a low miss-cleavage rate in only 20 minutes. And the MS-based high abundance protein removed 5-plex DIA method, which does not require extra protein depletion procedures, enables quantitative analysis of more than 600 proteins using an equivalent MS analysis time of 30 minutes per sample. The average relative error was 6.9%. We believe the method is beneficial for analyzing large numbers of trace-level clinical samples and broaden a vision for the discovery of low abundance protein markers.

biochemistry↗

Deep learning-based aberration compensation improves contrast and resolution in fluorescence microscopy

Optical aberrations hinder fluorescence microscopy of thick samples, reducing image signal, contrast, and resolution. Here we introduce a deep learning-based strategy for aberration compensation, improving image quality without slowing image acquisition, applying additional dose, or introducing more optics into the imaging path. Our method (i) introduces synthetic aberrations to images acquired on the shallow side of image stacks, making them resemble those acquired deeper into the volume and (ii) trains neural networks to reverse the effect of these aberrations. We use simulations and experiments to show that applying the trained de-aberration networks outperforms alternative methods, providing restoration on par with adaptive optics techniques; and subsequently apply the networks to diverse datasets captured with confocal, light-sheet, multi-photon, and super-resolution microscopy. In all cases, the improved quality of the restored data facilitates qualitative image inspection and improves downstream image quantitation, including orientational analysis of blood vessels in mouse tissue and improved membrane and nuclear segmentation in C. elegans embryos.

bioengineering↗

ABTrans: A Transformer-based model for predicting interaction between anti-Abeta antibodies and peptides

Understanding the recognition of antibodies and A{beta} peptide is crucial for the development of more effective therapeutic agents. Here we studied the interaction between anti-A{beta} antibodies and different peptides by building a deep learning model, using the dodecapeptide sequences elucidated from phage display and known anti-A{beta} antibody sequences collected from public sources. Our multi-classification model, ABTrans was trained to determine the four levels of binding ability between anti-A{beta} antibody and dodecapeptide: not binding, weak binding, medium binding, and strong binding. The accuracy of our model reached 0.8278. Using the ABTrans, we examined the cross-reaction of anti-A{beta} antibodies with other human amyloidogenic proteins, and we found that Aducanumab and Donanemab have the least cross-reactions with other human amyloidogenic proteins. We also systematically screened all human proteins interaction with eleven selected anti-A{beta} antibodies to identify possible peptide fragments that could be an off-target candidate. Key PointsO_LIABTrans is a Transformer-based model that was developed for the first time to predict the interaction between anti-A{beta} antibodies and peptides. C_LIO_LIABTrans was trained using a dataset with 1.5 million peptides and 110 anti-A{beta} antibodies. C_LIO_LIABTrans achieved an accuracy of 0.8278 and is capable of determining the four levels of binding ability between antibody and A{beta}: not binding, weak binding, medium binding, and strong binding. C_LIO_LIABTrans has potential applications in predicting off-target and cross-reactivity effects of antibodies and in designing new anti-A{beta} antibodies. C_LI

bioinformatics↗

Collaborative Augmented Reconstruction for Scaled Production of 3D Neuron Morphology in Mouse and Human Brains

Digital reconstruction of the intricate 3D morphology of individual neurons from microscopic images is widely recognized as a crucial challenge in both individual research laboratories and large-scale scientific projects focusing on cell types and brain anatomy. This task often fails both conventional manual reconstruction and state-of-the-art automatic reconstruction algorithms, even many of which are based on artificial intelligence (AI). It is also critical but challenging to organize multiple neuroanatomists to produce and cross-validate biologically relevant and agreeable reconstructions in scaled data production. Here we propose an approach based on collaborative human intelligence augmented by AI. Specifically, we have developed a Collaborative Augmented Reconstruction (CAR) platform for neuron reconstruction at scale. This platform allows for immersive interaction and efficient collaborative-editing of neuron anatomy using a variety of client devices, such as desktop workstations, virtual reality headsets, and mobile phones, enabling users to contribute anytime and anywhere and take advantage of several AI-based automation tools. We have tested CARs applicability for challenging mouse and human neurons towards a scaled and faithful data production. Our data indicate that the CAR platform is suitable for generating tens of thousands of neuronal reconstructions used in our companion studies.

neuroscience↗

Cell-autonomous targeting of arabinogalactan by host immune factors inhibits mycobacterial growth

Deeper understanding of the crosstalk between host cells and Mycobacterium tuberculosis (Mtb) provides crucial guidelines for the rational design of novel intervention strategies against tuberculosis (TB). Mycobacteria possess a unique complex cell wall with arabinogalactan (AG) as critical component. AG has been identified as a virulence factor of Mtb which is recognized by host galectin-9. Here we demonstrate that galectin-9 directly inhibited mycobacterial growth through AG-binding property of carbohydrate-recognition domain 2. Furthermore, IgG antibodies with AG specificity were detected in serum of TB patients. Based on the interaction between galectin-9 and AG, we developed monoclonal antibody (mAb) screening assay and identified AG-specific mAbs which profoundly inhibit Mtb growth. Mechanistically, proteomic profiling and morphological characterizations revealed that AG-specific mAbs regulate AG biosynthesis, thereby inducing cell wall swelling. Thus, direct AG-binding by galectin-9 or antibodies contributes to protection against TB. Our findings pave the way for the rational design of novel immunotherapeutic strategies for TB control.

immunology↗

Daptomycin forms a stable complex with phosphatidylglycerol for selective uptake to bacterial membrane

Daptomycin is a potent lipopeptide antibiotic used in the treatment of live-threatening Gram-positive infections, but the molecular mechanism of its interaction with bacterial membrane remains unclear. Here we show that this interaction is divided into two stages, of which the first is a fast and reversible binding of the drug to phospholipid membrane in milliseconds and the second is a slow and irreversible insertion into membrane in minutes, only in the presence of the bacteria-specific lipid phosphatidylglycerol, to a saturating point where the ratio of the drug to phosphatidylglycerol is 1:2. Fluorescence-based titration showed that the antibiotic simultaneously binds two molecules of phosphatidylglycerol with a nanomolar binding affinity in the presence of calcium ion. The resulting stable complex is easily formed in a test tube and readily isolated from the membrane of drug-treated bacterial cells, strongly supporting a unique drug uptake mechanism in which daptomycin forms a stable multi-component complex with calcium and phosphatidylglycerol. Revelation of this novel uptake mechanism provides fresh insights into the mode of action of daptomycin and paves the way to new strategies to attenuate resistance to the drug.

biochemistry↗

Circadian photoreceptor CRYPTOCHROME promotes wakefulness under short winter-like days via a GABAergic circuitry

A cardinal symptom of seasonal affective disorder (SAD, also known as winter depression) is hypersomnolence, while the cause of this "winter sleepiness" is not known. Here we found that lack of the circadian photoreceptor cryptochrome (cry) leads to increased sleep under short winter-like days in fruit flies, reminiscent of the hypersomnolence in SAD. CRY functions in neurons that synthesize the major inhibitory neurotransmitter GABA, including the small ventral lateral neurons which are known to be circadian pacemakers, and down-regulates the GABAergic tone. This in turn leads to increased neural activity of the wake-promoting large ventral lateral neurons, a subset of circadian neurons that are inhibited by GABA-A receptor. CRY protein is known to be degraded by light, thus rendering CRY to be functional within this GABAergic circuitry to enhance wakefulness only under short day length. Taken together, we demonstrate a mechanism that specifically regulates wakefulness under short winter-like days, which may provide insights regarding the winter sleepiness in SAD.

neuroscience↗

An updated model of shoot apical meristem regulation by ERECTA family and CLAVATA3 signaling pathways

The shoot apical meristem (SAM) gives rise to above-ground organs. The size of the SAM is relatively constant due to the balance of stem cell replenishment versus cell recruitment into developing organs. In angiosperms, the transcription factor WUSCHEL (WUS) promotes stem cell identity in the central zone of the SAM. WUS forms a negative feedback loop with a signaling pathway activated by CLAVATA3 (CLV3). In the periphery of the SAM, the ERECTA family (ERf) receptors promote cell differentiation and constrain the expression of WUS and CLV3. Here, we show that four ligands of ERfs redundantly inhibit CLV3 and WUS expression. Transcriptome analysis confirmed that WUS and CLV3 are the main targets of ERf signaling and uncovered several new ones. Analysis of promoter reporters indicated that in the vegetative meristem, the WUS expression domain mostly overlapped with the CLV3 domain and did not shift along the apical-basal axis in clv3. A 3D mathematical model reproduced the experimentally observed CLV3 and WUS expression patterns with fewer assumptions than earlier models. Based on these findings, we propose that CLV3 regulates cellular levels of WUS expression through autocrine signaling, while ERfs regulate WUS spatial expression, preventing its encroachment into the peripheral zone. One Sentence SummaryThrough autocrine signaling, CLV3 regulates the level of WUS expression in the vegetative SAM but not its location, while ERfs regulate the WUS spatial pattern, preventing its expansion into the peripheral zone.

plant biology↗