Biology subjects

Bai, G.

Publications and source records attributed to Bai, G..

33 records · Page 2Linked to original sources

bioRxiv2023

SAGERank: Inductive Learning of Protein-Protein Interaction from Antibody-Antigen Recognition using Graph Sample and Aggregate Networks Framework

Numerous experiments and computationally solved antibody-antigen interfaces offer the possibility of training deep-learning models to help predict their biological correlations. Predicting antibody-antigen docking and structure-based design represent significant long-term and therapeutically important challenges in computational biology. We present SAGERank, a general, configurable deep learning framework for antibody design using Graph Sample and Aggregate Networks, which mainly includes ranking docking decoys, detecting binding, and identifying biological interfaces. The model proved its reliability in three different tasks. For both problems ranking docking decoys and identifying biological interfaces, SAGERank is competitive with or outperforms, state-of-the-art methods. Besides, the SAGERank model still showed a high degree of confidence in determining whether the antibody-antigen could bind. All of these demonstrate the versatility of SAGERank for structural biology research. Most importantly, our study demonstrated the real potential of inductive deep learning to overcome small dataset problem in molecular science. The SAGERank models trained for antibody-antigen docking can be used to examine generally protein-protein interaction docking and differentiate crystal packing from biological interface.

bioinformatics↗

bioRxiv2023

HaploCatcher: An R Package for Prediction of Haplotypes

Wheat (Triticum aestivum L.) is crucial to global food security, but is often threatened by diseases, pests, and environmental stresses. Wheat stem sawfly (Cephus cinctus Norton) poeses a major threat to food security in the United States, and solid-stem varieties, which carry the stem-solidness locus (Sst1), are the main source of genetic resistance against sawfly. Marker-assisted selection uses molecular markers to identify lines possessing beneficial haplotypes, like that of the Sst1 locus. In this study, an R package titled "HaploCatcher" was developed to predict specific haplotypes of interest in genome-wide genotyped lines. A training population of 1,056 lines genotyped for the Sst1 locus, known to confer stem solidness, and genome-wide markers was curated to make predictions of the Sst1 haplotypes for 292 lines from the Colorado State University wheat breeding program. Predicted Sst1 haplotypes were compared to marker derived haplotypes. Our results indicated that the training set was substantially predictive, with kappa scores of 0.83 for k-nearest neighbors and 0.88 for random forest models. Forward validation on newly developed breeding lines demonstrated that a random forest model, trained on the total available training data, had comparable accuracy between forward and cross-validation. Estimated group means of lines classified by haplotypes from PCR-derived markers and predictive modeling did not significantly differ. The HaploCatcher package is freely available and may be utilized by breeding programs, using their own training populations, to predict haplotypes for whole genome sequenced early generation material. CORE IDEASO_LIIdentification, introgression, and frequency increase of large effect loci are important for cultivar development. C_LIO_LIThe Sst1 locus has a significant effect on cutting score in fields exposed to sawfly infestation. C_LIO_LIHistorical genetic information can be utilized to predict haplotypes for lines which have genome-wide genetic data. C_LIO_LIAn R package, HaploCatcher, has been developed to facilitate this analysis in other programs. C_LI

plant biology↗

bioRxiv2022

Conserved NIMA kinases regulate multiple steps of endocytic trafficking

Human NIMA-related kinases have primarily been studied for their roles in cell cycle progression (NEK1/2/6/7/9), checkpoint-DNA-damage control (NEK1/2/4/5/10/11), and ciliogenesis (NEK1/4/8). We previously showed that Caenorhabditis elegans NEKL-2 (NEK8/9 homolog) and NEKL-3 (NEK6/7 homolog) regulate apical clathrin-mediated endocytosis (CME) in the worm epidermis and are essential for molting. Here we show that NEKL-2 and NEKL-3 also have distinct roles in controlling endosome function and morphology. Specifically, loss of NEKL-2 led to enlarged early endosomes with long tubular extensions but showed minimal effects on other compartments. In contrast, NEKL-3 depletion caused pronounced defects in early, late, and recycling endosomes. Consistently, NEKL-2 was strongly localized to early endosomes, whereas NEKL-3 was localized to multiple endosomal compartments. Loss of NEKLs also led to variable defects in the recycling of two resident cargoes of the trans-Golgi network (TGN), MIG-14/Wntless and TGN-38/TGN38, which were missorted to lysosomes after NEKL depletion. In addition, defects were observed in the uptake of clathrin-dependent (SMA-6/Type I BMP receptor) and independent cargoes (DAF-4/Type II BMP receptor) from the basolateral surface of epidermal cells after NEKL-2 or NEKL-3 depletion. Complementary studies in human cell lines further showed that siRNA knockdown of the NEKL-3 orthologs NEK6 and NEK7 led to missorting of the mannose 6-phosphate receptor from endosomes. Moreover, in multiple human cell types, depletion of NEK6 or NEK7 disrupted both early and recycling endosomal compartments, including the presence of excess tubulation within recycling endosomes, a defect also observed after NEKL-3 depletion in worms. Thus, NIMA family kinases carry out multiple functions during endocytosis in both worms and humans, consistent with our previous observation that human NEKL-3 orthologs can rescue molting and trafficking defects in C. elegans nekl-3 mutants. Our findings suggest that trafficking defects could underlie some of the proposed roles for NEK kinases in human disease. Author SummaryIntracellular trafficking is an evolutionary conserved process whereby cargoes, which include proteins, lipids, and other macromolecules, are internalized by cells, packaged into vesicles, and distributed to their proper places within the cell. This study demonstrated that two conserved NIMA-related kinases, NEKL-2 and NEKL-3, are required for the transport of multiple cargoes in the epidermis of C. elegans. NEKL-2 and NEKL-3 function at organelles, called endosomes, to regulate their morphology and control the sorting of cargoes between different intracellular compartments. In the absence of NEKL activities, various cargoes, including components of the BMP and Wnt signaling pathways, were misregulated. Our studies are further supported by results showing that the human counterparts of NEKL-3, NEK6 and NEK7, were also required for maintaining endosome morphologies and for the proper sorting of cargo in human cells. Notably, NIMA-kinases are well studied for their roles in cell cycle regulation, and overexpression of these kinases is linked to cancer formation and poor prognosis. Our study suggests their role in cancer progression could be partly due to the abnormal intracellular trafficking of conserved signaling components with known roles in cancer formation.

cell biology↗

bioRxiv2022

T1K: efficient and accurate KIR and HLA genotyping with next-generation sequencing data

Killer immunoglobulin-like receptor (KIR) genes and human leukocyte antigen (HLA) genes are highly polymorphic in a population and play important roles in innate and adaptive immunity. We have developed a novel computational method T1K that can efficiently and accurately infer the KIR or HLA alleles from next-generation sequencing data. T1K is flexible and is compatible with various sequencing platforms including RNA-seq and genomic sequencing data. We applied T1K on CD8+ T cell single-cell RNA-seq data, and identified that KIR2DL4 allele expression levels were enriched in tumor-specific CD8+ T cells.

bioinformatics↗

bioRxiv2022

Intermediate Filaments Associate with Aggresome-like Structures and Influence Rate of Cellular Expulsion of Neuronal Disease Aggregates

Under conditions of proteostasis disequilibrium, neurons can enhance intracellular and extracellular protective mechanisms to guard against neurotoxicity. In mammals, an intracellular response to severe proteostasis imbalance that results from proteosome inhibition is the formation of juxtanuclear intermediate filament-surrounded, aggregate-filled aggresomes, which sequester threatening aggregates for later disposal via lysosomal degradation. Highly proteo-stressed neurons can also engage the assistance of neighboring cells in aggregate removal by loading threatening materials into large exopher vesicles that are transferred to neighboring cells for remote degradation of contents, a process that has been suggested to be analogous to the process that enables aggregate spreading in the human brain in neurodegenerative disease. In C. elegans these large extruded vesicles are called exophers. Here we document that players involved in aggresome biology are required for the elimination of potentially deleterious materials in neuronal exophers. We show that in proteostressed C. elegans touch receptor neurons, intermediate filament proteins IFD-1 and IFD-2 can assemble into juxtanuclear structures with multiple molecular and cellular characteristics of mammalian aggresomes. IFD-concentrating structures depend upon orthologs of mammalian adapter proteins, dynein motors, and microtubule integrity for aggregate collection into juxtanuclear compartments where they associate with ubiquitinated and neurotoxic polyglutamine expansion proteins. Strikingly, disruption of aggresome-decoration genes encoding IFDs or disruption of the BAG/14-3-3/Hsc70 adapter that promote aggregate loading of aggresome-like organelles, lowers exopher production via a cell autonomous mechanism. Although aggresome-like structures are not mandatory exopher cargo, IFD compartments can be extruded from neurons in exophers, revealing a previously unreported strategy to eliminate neuronal aggresome-like organelles via transfer to neighboring cells. Human IF neurofilament light chain hNFL can partially substitute for C. elegans IFD-2 proteins in promoting exopher production, indicating conservation of the capacity of intermediate filaments to influence neuronal aggregate extrusions across phyla. In sum, we identify a requirement for specific intermediate filaments, counterparts of human biomarkers of neuronal injury and disease and major components of Parkinsons disease Lewy bodies, in C. elegans neuronal aggresome-like organelle formation and large vesicle exopher extrusion from stressed neurons.

cell biology↗

bioRxiv2022

Large vesicle extrusion from C. elegans neurons requires phagocytic interaction via the ARF-6 and CED-1/DRAPER pathways

C. elegans neurons under stress can produce giant vesicles, several microns in diameter, called exophers. Current models suggest that exophers are neuroprotective, providing a mechanism for stressed neurons to eject toxic protein aggregates and organelles. However, little is known of the fate of the exopher once it leaves the neuron. We found that exophers produced by mechanosensory neurons in C. elegans are engulfed by surrounding hypodermal skin cells and are then broken up into numerous smaller vesicles that acquire hypodermal phagosome maturation markers, with vesicular contents gradually degraded by hypodermal lysosomes. Consistent with the hypodermis acting as an exopher phagocyte, we found that exopher removal requires hypodermal actin and Arp2/3, and the hypodermal plasma membrane adjacent to newly formed exophers accumulates dynamic F-actin during budding. Efficient fission of engulfed exopher-phagosomes to produce smaller vesicles and degrade their contents requires phagosome maturation factors SAND-1/Mon1, GTPase RAB-35, the CNT-1 ARF-GAP, and microtubule motor associated GTPase ARL-8, suggesting a close coupling of phagosome fission and phagosome maturation. Lysosome activity was required to degrade exopher contents in the hypodermis but not for exopher-phagosome resolution into smaller vesicles. Importantly, we found that GTPase ARF-6 and effector SEC-10/Exocyst activity in the hypodermis, along with the CED-1 phagocytic receptor, is required for efficient production of exophers by the neuron. Our results indicate that the neuron requires specific interaction with the phagocyte for an efficient exopher response, a mechanistic feature potentially conserved with mammalian exophergenesis, and similar to neuronal pruning by phagocytic glia that influences neurodegenerative disease.

neuroscience↗

bioRxiv2022

Noninvasive cancer detection by extracting and integrating multi-modal data from whole-methylome sequencing of plasma cell-free DNA

AbstractPlasma cell-free DNA (cfDNA) methylation and fragmentation signatures have been shown to be valid biomarkers for blood-based cancer detection. However, conventional methylation sequencing assays are inapplicable for fragmentomic profiling due to bisulfite-induced DNA damage. Here using enzymatic conversion-based low-pass whole-methylome sequencing (WMS), we developed a novel approach to comprehensively interrogate the genome-wide plasma methylation, fragmentation, and copy number profiles for sensitive and noninvasive multi-cancer detection. With plasma WMS data from a clinical cohort comprising 497 healthy controls and 780 patients with both early- and advanced-stage cancers of the breast, colorectum, esophagus, stomach, liver, lung, or pancreas, genomic features including methylation, fragmentation size, copy number alteration, and fragment end motif were extracted individually and subsequently integrated to develop an ensemble cancer classifier, called THEMIS, using machine learning algorithms. THEMIS outperformed individual biomarkers for differentiating cancer patients of all seven types from healthy individuals and achieved a combined area under the curve value of 0.971 in the independent test cohort, translating to a sensitivity of 86% and early-stage (I and II) sensitivity of 77% at 99% specificity. In addition, we built a cancer signal origin classifier with true-positive cancer samples at 100% specificity based on methylation and fragmentation profiling of tissue-specific accessible regulatory elements, which localized cancer-like signal to a limited number of clinically informative sites with 66% accuracy. Overall, this proof-of-concept work demonstrates the feasibility of extracting and integrating multi-modal biomarkers from a single WMS run for noninvasive detection and localization of common cancers across stages.

cancer biology↗

bioRxiv2022

Wild-type allele of TaHRC suppresses calcium-mediated plant immune response by hijacking TaCAXIP4 to trigger FHB susceptibility in wheat

Fusarium head blight (FHB) is one of the most destructive diseases of wheat worldwide. Epidemics of FHB cause a serious reduction in grain yield and quality of wheat and result in significant economic losses to wheat producers. Recently, we have cloned a histidine-rich calcium-binding protein gene (TaHRC) as the causal gene for Fhb1 and demonstrated that the wild-type allele of TaHRC conditions FHB susceptibility and a large deletion including the start codon resulted in FHB resistance. However, the molecular mechanisms on how TaHRC regulating FHB susceptibility remains unknown. In this study, we conducted yeast two-hybrid screening (Y2H) against the wheat cDNA expression libraries using TaHRC as bait and identified a cation exchanger (CAX)-interacting protein 4 (TaCAXIP4) as the candidate protein that interacts with TaHRC to affect calcium transport activity. The strong interaction was further confirmed by Bimolecular fluorescence complementation (BiFC) assays. Using gene editing, we edited three different sites (one before and one within and one after the NLS domain) of TaHRC in a susceptible wheat cultivar Bobwhite using the CRISPR/Cas9 gene editing technology and demonstrated the N-terminus carrying NLS domain of TaHRC plays a critical role for the interaction and conditions TaHRC function on FHB susceptibility. We determined that the interaction between TaCAXIP4 and TaHRC occurs in the nuclei of cells by subcellular colocalization assay. Intriguingly, we found TaHRC can sequester TaCAXIP4 to suppress the Ca2+ transporting activity of TaCAX1 (a H+/Ca2+ antiporter) through yeast calcium suppression assay and suggested wild-type TaHRC may hijack TaCAXIP4 to suppresses calcium-mediated plant immune response during Fusarium infection in wheat. Furthermore, we performed the reactive oxygen species (ROS) assays and further showed that TaHRC might suppress the chitin-triggered plant immune responses during Fusarium infection by sequestering TaCAXIP4 to trigger FHB susceptibility, which facilitates the pathogen spread within a wheat spike. This work provides first line of evidence to support wild type Fhb1 is a susceptible gene and how Fhb1 wild type allele regulate FHB susceptibility.

plant biology↗

bioRxiv2022

Multiplexed promoter and gene editing in wheat using the virus-based guide RNA delivery system

The low efficiency of genetic transformation and gene editing across diverse cultivars hinders the broad application of CRISPR technology for crop improvement. The development of virus-based methods of CRISPR-Cas system delivery into the plant cells holds great promise to overcome these limitations. Here, we applied the barley stripe mosaic virus (BSMV) for delivering guide RNAs (sgRNA) into the Cas9-expressing wheat lines to create targeted deletions in the promoter of a transcription factor and to perform multiplexed editing of agronomic genes. We demonstrate that pooled BSMV-sgRNAs could be used to generate heritable targeted deletions and multiple mutations in the genome. We transferred the high-expressing allele of Cas9 into adapted spring and winter cultivars and successfully performed the BSMV-sgRNA-based editing of two agronomic genes. The strategies presented in our study could be applied to any cultivar for creating new cis-regulatory diversity or targeting multiple genes in biological pathways or QTL regions, opening possibilities for the effective engineering of crop genomes and accelerating gene discovery and trait improvement efforts.

genetics↗

bioRxiv2022

Development and optimization of a Barley stripe mosaic virus (BSMV)-mediated gene editing system to improve Fusarium head blight (FHB) resistance in wheat

Fusarium head blight (FHB) is a devastating disease in wheat that causes million dollars of wheat yield losses annually in the U.S.A. Recently we demonstrated that wheat carry FHB susceptible genes and knocking out the susceptible gene increased FHB resistance, which suggests that manipulating susceptible genes using gene editing may open a new avenue to create new sources of FHB resistance. However, wheat genome editing uses gene transformation to deliver CRISPR/Cas9 and gRNA into plants, and most wheat genotypes are not suitable for transformation due to low rates of callus induction and regeneration, therefore it cannot be used in practical wheat breeding. In this study, we developed a new Barley stripe mosaic virus (BSMV)-mediated gRNA delivery system that does not need the gene transformation and tissue culture and it can be used in any genotypes for gene function validation and editing. We used this system edited the susceptible allele of Fhb1, a major FHB resistance gene. We demonstrated that the edited trait is heritable in different genetic backgrounds and knocking out Fhb1 susceptible allele improved FHB resistance in wheat. We also modified system to improve editing efficiency by using floral dip agroinfiltration and adding RNA mobility sequences to the gRNA in the viral vectors. We believe this work will facilitate wheat FHB resistance research and gene editing in cereal crops and will benefit cereal crop researchers and breeders worldwide.

plant biology↗

bioRxiv2021

Development of the Wheat Practical Haplotype Graph Database as a Resource for Genotyping Data Storage and Genotype Imputation

To improve the efficiency of high-density genotype data storage and imputation in bread wheat (Triticum aestivum L.), we applied the Practical Haplotype Graph (PHG) tool. The wheat PHG database was built using whole-exome capture sequencing data from a diverse set of 65 wheat accessions. Population haplotypes were inferred for the reference genome intervals defined by the boundaries of the high-quality gene models. Missing genotypes in the inference panels, composed of wheat cultivars or recombinant inbred lines genotyped by exome capture, genotyping-by-sequencing (GBS), or whole-genome skim-seq sequencing approaches, were imputed using the wheat PHG database. Though imputation accuracy varied depending on the method of sequencing and coverage depth, we found 93% imputation accuracy with 0.01x sequence coverage, which was only slightly lower than the accuracy obtained using the 0.5x sequence coverage (96.9%). Compared to Beagle, on average, PHG imputation was ~4% (p-value = 0.00027) more accurate, and showed 27% higher accuracy at imputing a rare haplotype introgressed from a wild relative into wheat. The reduced accuracy of imputation with GBS data (90.4%) is likely associated with the small overlap between GBS markers and the exome capture dataset, which was used for constructing PHG. The highest imputation accuracy was obtained with exome capture for the wheat D genome, which also showed the highest levels of linkage disequlibrium and proportion of identity-by-descent regions among accessions in our reference panel. We demonstrate that genetic mapping based on genotypes imputed using PHG identifies SNPs with a broader range of effect sizes that together explain a higher proportion of genetic variance for heading date and meiotic crossover rate compared to previous studies.

genomics↗

bioRxiv2021

The Nicotiana tabacum Mediator subunit MED25 regulates nicotine biosynthesis through interacting with the basic helix-loop-helix (bHLH) transcription factor NtMYC2s

Nicotine is one of the most important secondary metabolites in tobacco, and its biosynthesis can be induced by topping and jasmonic acid treatment. NtMYC2s play pivotal roles in the regulation of nicotine. The mediator server as a bridge betwen the transcription factors and RNA polymerase in order to facilitates transcription and functions in plants. However, the role of mediator in the regulation of nicotine biosynthesis remains unknown. In this study, we firstly identify the NtMED25 through homologous analysis. NtMED25 interacts with NtMYC2s through the MD region. Interestingly, the nicotine content is decreased in the the knock-down transgenic lines of NtMED25, and the expression levels of two nicotine biosynthesis genes, NtQPT2 and NtPMT2, are also reduced when compared with that in the wild-type plants. Furthermore, NtMED25 enhances the binding of NtMYC2a/ NtMYC2b to the promoter of NtPMT2 and NtQPT2, and then facilitates the nicotine biosynthesis. Therefore, our study revealed the function of mediator in the regulation of nicotine, and provide the insight role on the transcriptional regulation of plant secondary metabolites.

plant biology↗

bioRxiv2021

CHIPS: A Snakemake pipeline for quality control and reproducible processing of chromatin profiling data

MotivationThe chromatin profile measured by ATAC-seq, ChIP-seq, or DNase-seq experiments can identify genomic regions critical in regulating gene expression and provide insights on biological processes such as diseases and development. However, quality control and processing chromatin profiling data involve many steps, and different bioinformatics tools are used at each step. It can be challenging to manage the analysis. ResultsWe developed a Snakemake pipeline called CHIPS (CHromatin enrichment Processor) to streamline the processing of ChIP-seq, ATAC-seq, and DNase-seq data. The pipeline supports single- and paired-end data and is flexible to start with FASTQ or BAM files. It includes basic steps such as read trimming, mapping, and peak calling. In addition, it calculates quality control metrics such as contamination profiles, PCR bottleneck coefficient, the fraction of reads in peaks, percentage of peaks overlapping with the union of public DNaseI hypersensitivity sites, and conservation profile of the peaks. For downstream analysis, it carries out peak annotations, motif finding, and regulatory potential calculation for all genes. The pipeline ensures that the processing is robust and reproducible. AvailabilityCHIPS is available at https://github.com/liulab-dfci/CHIPS

bioinformatics↗

bioRxiv2020

Expanding the range of editable targets in the wheat genome using the variants of the Cas12a and Cas9 nucleases

The development of CRISPR-based editors having different protospacer adjacent motif (PAM) recognition specificities, or guide RNA length/structure requirements broadens the range of possible genome editing applications. Here, we evaluated the natural and engineered variants of Cas12a (FnCas12a from Francisella novicida and LbCas12a from Lachnospiraceae bacterium) and Cas9 for wheat genome editing efficiency and ability to induce heritable mutations in endogenous genes controlling important agronomic traits in wheat. Unlike FnCas12a, LbCas12a was able to induce mutations in the wheat genome in the current study, even though with a lower rate than that reported for SpCas9. The eight-fold improvement in the gene editing efficiency was achieved for LbCas12a by using the guide RNAs flanked by ribozymes and driven by the RNA polymerase II promoter from switchgrass. The efficiency of multiplexed genome editing (MGE) using LbCas12a was mostly similar to that obtained using the simplex RNA guides. A LbCas12a-MGE construct was successfully applied for generating heritable mutations in a gene controlling grain size and weight in wheat. We show that the range of editable loci in the wheat genome could be expanded by using the engineered variants of Cas12a (LbCas12a-RVR) and Cas9 (Cas9-NG and xCas9) that recognize the TATV and NG PAMs, respectively, with the Cas9-NG showing higher editing efficiency on the targets with atypical PAMs compared to xCas9. In conclusion, our study reports the set of validated natural and engineered variants of Cas12a and Cas9 editors for targeting loci in the wheat genome not amenable to Cas9-based modification.

genetics↗

bioRxiv2020

Association of gut microbiota with cerebral cortex and cerebrovascular abnormality in human mild traumatic brain injury

Key roles of the gut-brain axis in brain injury development have been suggested in various mouse models; however, little is known about its functional significance in human mild traumatic brain injury (TBI). Here, we decipher this axis by profiling the gut microbiota in 98 acute mild TBI patients and 62 matched controls, and subgroup of them also measured circulating mediators and applied neuroimaging. Mild TBI patients had increased -diversity and different overall microbial compositions compared with controls. 25-microbial genus classifiers distinguish patients from controls with an area under the receiver operating characteristic curve (AUC) of 0.889, while adding serum mediators and neuroimaging features further improved performance even in a small sample size (AUC = 0.969). Numerous correlations existed between gut bacteria, aberrant cortical thickness and cerebrovascular injury. Co-occurrence network analysis revealed two unique gut-brain axes in patients: 1) altered intestinal Lachnospiraceae_NK4A136_group and Eubacterium_ruminantium_group-increased serum GDNF-subcallosal hypertrophy and cerebrovascular injury; 2) decreased intestinal Eubacterium_xylanophilum_group-upregulated IL-6-thinned anterior insula. Our findings provide a new integrated mechanistic understanding and diagnostic model of mild TBI.

microbiology↗