Biology subjects

Xie, K.

Publications and source records attributed to Xie, K..

At least 55 records · Page 3Linked to original sources

bioRxiv2023

TESOGENASE, An Engineered Nuclease Editor for Enhanced Targeted Genome Integration

Summary/AbstractNon-viral DNA donor template has been widely used for targeted genomic integration by homologous recombination (HR). This process has become more efficient with RNA guided endonuclease editor system such as CRISPR/Cas9. Circular single stranded DNA (cssDNA) has been harnessed previously as a genome engineering catalyst (GATALYST) for efficient and safe targeted gene knock-in. However, the engineering efficiency is bottlenecked by the nucleoplasm trafficking and genomic tethering of cssDNA donor, especially for extra-large transgene integration. Here we developed enGager, enhanced GATALYST associated genome editor system by fusion of nucleus localization signal (NLS) peptide tagged Cas9 with various single stranded DNA binding protein modules through a GFP reporter Knock-in screening. The enGager system assembles an integrative genome integration machinery by forming tripartite complex for engineered nuclease editors, sgRNA and ssDNA donors, thereby facilitate the nucleus trafficking of DNA donors and increase their active local concentration at the targeted genomic site. When applied for genome integration with cssDNA donor templates to diverse genomic loci in various cell types, these enGagers outperform unfused editors. The enhancement of integration efficiency ranges from 1.5- to more than 6-fold, with the effect being more prominent for > 4Kb transgene knock-in in primary cells. We further demonstrated that enGager mediated enhancement for genome integration is ssDNA, but less dsDNA dependent. Using one of the mini-enGagers, we demonstrated large chimeric antigen receptor (CAR) transgene integration in primary T cells with exceptional efficiency and anti-tumor function. These tripartite editors with ssDNA optimized genome engineering system (TESOGENASETM) add a set of novel endonuclease editors into the gene-editing toolbox for potential cell and gene therapeutic development based on ssDNA mediated non-viral genome engineering. HighlightO_LIA reporter Knock-in screening establishes enGager system to identify TESOGENASE editor to improving ssDNA mediated genome integration C_LIO_LIMini-TESOGENASEs developed by fusing Cas9 nuclease with novel ssDNA binding motifs C_LIO_LImRNA mini-TESOGENASEs enhance targeted genome integration via various non-viral delivery approaches C_LIO_LIEfficient functional CAR-T cell engineering by mini-TESOGENASE C_LI

bioengineering↗

bioRxiv2023

Cerebral perfusion alterations in temporal lobe epilepsy: Structural underpinnings and network disruptions

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSOO_SCPLOWBJECTIVEC_SCPLOWC_ST_ABSNeuroimaging has been the prevailing method to study brain networks in temporal lobe epilepsy (TLE), showing widespread alterations beyond the mesiotemporal lobe. Despite the critical role of the cerebrovascular system in maintaining whole-brain structure and function, changes in cerebral blood flow (CBF) remain incompletely understood in the disease. MO_SCPLOWETHODSC_SCPLOWWe studied 24 individuals with pharmaco-resistant TLE and 38 healthy adults using multimodal 3T magnetic resonance imaging. We compared regional CBF changes in patients relative to controls and related our perfusion findings to morphological and microstructural metrics. We further probed inter-regional vascular networks in TLE, using graph theoretical CBF covariance analysis. Finally, we assessed the effects of disease duration to study progressive changes. RO_SCPLOWESULTSC_SCPLOWCompared to controls, individuals with TLE showed widespread CBF reductions, predominantly in fronto-temporal regions, with 83% of patients showing more marked decreases ipsilateral than contralateral to the seizure focus. Parallel structural profiling and network-based models showed that cerebral hypoperfusion may be partly constrained by grey and white matter changes and topologically segregated from whole-brain perfusion networks. Negative effects of progressive disease duration further targeted regional CBF profiles in patients. Findings were confirmed in a subgroup of patients who remained seizure-free after surgery. IO_SCPLOWNTERPRETATIONC_SCPLOWOur multimodal findings provide insights into vascular contributions to TLE pathophysiology and highlight their clinical potential in seizure lateralization.

neuroscience↗

bioRxiv2023

Atypical connectome topography and signal flow in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is one of the most common pharmaco-resistant epilepsies in adults. While hippocampal pathology is the hallmark of this condition, emerging evidence indicates that brain alterations extend beyond the mesiotemporal epicenter and affect macroscale brain function and cognition. We studied macroscale functional reorganization in TLE, explored structural substrates, and examined cognitive associations. We investigated a multisite cohort of 95 patients with pharmaco-resistant TLE and 95 healthy controls using state-of-the-art multimodal 3T magnetic resonance imaging (MRI). We quantified macroscale functional topographic organization using connectome dimensionality reduction techniques and estimated directional functional flow using generative models of effective connectivity. We observed atypical functional topographies in patients with TLE relative to controls, manifesting as reduced functional differentiation between sensory/motor networks and transmodal systems such as the default mode network, with peak alterations in bilateral temporal and ventromedial prefrontal cortices. TLE-related topographic changes were consistent in all three included sites and reflected reductions in hierarchical flow patterns between cortical systems. Integration of parallel multimodal MRI data indicated that these findings were independent of TLE-related cortical grey matter atrophy, but mediated by microstructural alterations in the superficial white matter immediately beneath the cortex. The magnitude of functional perturbations was robustly associated with behavioral markers of memory function. Overall, this work provides converging evidence for macroscale functional imbalances, contributing microstructural alterations, and their associations with cognitive dysfunction in TLE.

neuroscience↗

bioRxiv2023

Key common genes and pathways in ulcerative colitis and ankylosing spondylitis based on bioinformatics analysis

Associations between ulcerative colitis (UC) and ankylosing spondylitis (AS) have been observed in multiple studies, but the common etiology of UC and AS remain unknown. Thus, the current research was conducted to investigate the shared genes and relevant mechanisms in UC and AS. GSE87466 and GSE25101 datasets were used to identify DEGs involved in UC and AS, respectively. The clusterProfiler R package was utilized to detect the biological processes of DEGs in UC and AS. The performance of common DEGs in distinguishing UC or AS samples from control ones were evaluated by ROC curves. The miRWalk, Cistrome and TransmiR database were utilized to construct the network of TF-miRNA-diagnostic biomarker. GSEA method and CTD database were used to investigate the common KEGG pathways shared by UC and AS. In addition, CTD database was also used to detect the interaction score between diagnostic biomarkers and diseases associated with UC or AS. Moreover, prospective diagnostic biomarker-targeting drugs were identified using the DGIdb database. A total of 20 common DEGs were obtained by analyzing data in GSE97466 and GSE25101 datasets. ROC curves revealed that GMFG, GNG11, CLEC4D, CMTM2, VAMP5, S100A8, S100A12 and DGKQ may serve as diagnostic biomarkers for the individuals with AS and UC. A network of TF-miRNA-diagnostic biomarker, composed of 212 nodes and 721 edges, was constructed and visualized by Cytoscape software. Toll-like receptor signaling pathway, antigen processing and presentation, allograft rejection, viral myocarditis, pathways in cancer, graft versus host disease and natural killer cell mediated cytotoxicity were identified as common pathways in UC and AS. For the first time, our study identified 8 common key genes and 7 common pathways in UC and AS. These findings may help to clarify the relationship between UC and AS, and provide guidance in the diagnosis and treatment of UC and AS patients. Author SummaryAnkylosing spondylitis (AS) and Ulcerative colitis (UC) are two types of autoimmune diseases that often co-occur. The simultaneous onset of both diseases often results in severe clinical manifestations and limited therapeutic efficacy. So there is an urgent need to gain a deeper understanding of the causes of UC and AS in order to develop more effective treatment strategies. In this study, we explored the genes and pathways commonly involved in two diseases, constructed a transcriptional network, and further investigated potential drugs. The discoveries could potentially offer insights into the connection between UC and AS, and assist in identifying and managing patients with UC and AS.

bioinformatics↗

bioRxiv2022

Circular single-stranded DNA is a superior homology-directed repair donor template for efficient genome engineering

The toolbox for genome editing in basic research and therapeutic applications is rapidly expanding. While efficient targeted gene ablation using nuclease editors has been demonstrated from bench to bedside, precise transgene integration remains a technical challenge. AAV6 has been a prevalent donor carrier for homology-directed repair (HDR) mediated genome engineering but has reported safety issues, manufacturing constraints, and restricted applications due to its 4.5 Kb packaging limit. Non-viral targeted genetic knock-ins rely primarily on double-stranded DNA (dsDNA) and linear single-stranded DNA (lssDNA) donors. Both dsDNA and lssDNA have been previously demonstrated to have low efficiency and cytotoxicity. Here, we developed a non-viral genome writing catalyst (GATALYST) system which allows production of ultrapure, minicircle single-stranded DNAs (cssDNAs) up to [~]20 Kb as donor templates for highly efficient precision transgene integration. cssDNA donors enable knock-in efficiency of up to 70% in induced pluripotent stem cells (iPSCs), superior efficiency in multiple clinically relevant primary cell types, and at multiple genomic loci implicated for clinical applications with various nuclease editor systems. When applied to immune cell engineering, cssDNA engineered CAR-T cells exhibit more potent and durable anti-tumor efficacy than those engineered from AAV6 viral vectors. The exceptional precision and efficiency, improved safety, payload flexibility, and scalable manufacturability of cssDNA unlocks the full potential of genome engineering with broad applications in therapeutic development, disease modeling and other research areas. HighlightsO_LIScalable production of minicircle ssDNA (cssDNA) with highly engineered phagemid system C_LIO_LIGenome writing catalyst (GATALYST) system with cssDNA donor template demonstrates superior efficiency and safety in various cell types and genomic loci C_LIO_LIGATALYST gene writing system enables ultra-large transgene integration C_LIO_LIcssDNA engineered CAR-T outperforms AAV engineered CAR-T with superior anti-tumor function C_LI

bioengineering↗

bioRxiv2022

Loss of H3.1K27me1 in Arabidopsis confers resistance to Geminivirus by sequestering DNA repair proteins onto rDNA and defense-related genes

The H3 methyltransferases ATXR5 and ATXR6 deposit H3.1K27me1 to heterochromatin to prevent genomic instability and transposon reactivation. Here, we report that atxr5 atxr6 mutants displayed robust resistance to Geminivirus. The viral resistance correlated with activation of DNA repair pathways, but not with transposon reactivation or heterochromatin amplification. We identified RAD51 and RPA1A as partners of virus-encoded Rep protein. The two DNA repair proteins showed increased binding to heterochromatic regions and defense-related genes in atxr5 atxr6 vs wild type plants. Consequently, the proteins had reduced interactions to viral DNA in the mutant, thus hampering viral replication. Additionally, RAD51 recruitment to the host genome arose via BRCA1, HOP2 and CYCB1, and this recruitment was essential for viral resistance in atxr5 atxr6. Thus, Geminiviruses adapt to healthy plants by hijacking its DNA repairing pathways for replication, but the host could retain DNA repairing proteins via sacrificing its genome stability to suppress viral infection.

genetics↗

bioRxiv2022

Atypical intrinsic neural timescales in temporal lobe epilepsy

ObjectiveTemporal lobe epilepsy (TLE) is the most common drug-resistant epilepsy in adults. Here, we aimed to profile local neural function in TLE in vivo, building on prior evidence that has identified widespread structural alterations. Using multimodal MRI, we mapped intrinsic neural timescales (INT) at rest, examined associations to TLE-related structural compromise, and evaluated the clinical utility of INT. MethodsWe studied 46 TLE patients and 44 healthy controls from two independent sites, and mapped INT changes in patients relative to controls across hippocampal, subcortical, and neocortical regions. We examined region-specific associations to structural alterations and explored effects of age and epilepsy duration. A supervised machine learning paradigm assessed utility of INT for classifying patients-vs-controls and seizure focus lateralization. ResultsRelative to controls, TLE showed marked INT reductions across multiple regions bilaterally, indexing faster changing resting activity, with strongest effects in ipsilateral medial and lateral temporal regions, and sensorimotor cortices. Findings were consistent in each site and robust, albeit with reduced effect sizes, when correcting for structural alterations. TLE-related INT reductions increased with advancing disease duration, yet findings differed from aging effects seen in controls. Classifiers based on INT distinguished patients-vs-controls (balanced accuracy, 5-fold: 76{+/-}2.65%; cross-site, 72-83%) and lateralized the focus in TLE (balanced accuracy, 5-fold: 96{+/-}2.10%; cross-site, 95-97%) with high accuracies and generalization. ConclusionsOur findings robustly demonstrate atypical macroscale function in TLE in a topography that extends beyond mesiotemporal epicenters. INT measurements can assist in TLE diagnosis, seizure focus lateralization, and monitoring of disease progression, which suggests clinical utility.

neuroscience↗

bioRxiv2022

Deep Phenotyping and Lifetime Trajectories Reveal Limited Effects of Longevity Regulators on the Aging Process in C57BL/6J Mice

Current concepts regarding the biology of aging are based on studies aimed at identifying factors regulating natural lifespan. However, lifespan as a sole proxy measure for aging can be of limited value because it may be restricted by specific sets of pathologies, rather than by general physiological decline. Here, we employed large-scale phenotyping to analyze hundreds of phenotypes and thousands of molecular markers across tissues and organ systems in a single study of aging male C57BL/6J mice. For each phenotype, we established lifetime profiles to determine when age-dependent phenotypic change is first detectable relative to the young adult baseline. We examined central genetic and environmental lifespan regulators (putative anti-aging interventions, PAAIs; the following PAAIs were examined: mTOR loss-of-function, loss-of-function in growth hormone signaling, dietary restriction) for a possible countering of the signs and symptoms of aging. Importantly, in our study design, we included young treated groups of animals, subjected to PAAIs prior to the onset of detectable age-dependent phenotypic change. In parallel to our studies in mice, we assessed genetic variants for their effects on age-sensitive phenotypes in humans. We observed that, surprisingly, many PAAI effects influenced phenotypes long before the onset of detectable age-dependent changes, rather than altering the rate at which these phenotypes developed with age. Accordingly, this subset of PAAI effects does not reflect a targeting of age-dependent phenotypic change. Overall, our findings suggest that comprehensive phenotyping, including the controls built in our study, is critical for the investigation of PAAIs as it facilitates the proper interpretation of the mechanistic mode by which PAAIs influence biological aging. HighlightsO_LIPhenotyping at scale defines lifetime trajectories of age-dependent changes in C57BL/6J mice C_LIO_LICentral genetic and environmental lifespan regulators (putative anti-aging interventions; PAAIs) influence age-sensitive phenotypes (ASPs) often long before the appearance of age-dependent changes in these ASPs C_LIO_LICorresponding genetic variants in humans also have age-independent effects C_LIO_LIMany PAAI effects shift the baseline of ASPs rather than slowing their rate of change C_LI

physiology↗

bioRxiv2022

Cost-effectively dissecting the genetic architecture of complex wool traits in rabbits by low-coverage sequencing

Wool traits of rabbits are important in fiber production and model organism research on hair growth, while the genetic architecture remains obscure. In this study, we focused on wool characteristics in Angora rabbits, a well-known fiber breed. Balancing genotyping cost and variant detection, we proposed low-coverage whole genome sequencing (LCS) followed by genotype imputation for genotyping. Different genotype imputation strategies, sequencing coverages and sample sizes were compared, and we found by BaseVar + STITCH, genotyping reached high accuracy (>0.97) at a depth of 1.0X and a sample size > 300. Multivariate GWAS followed by conditional GWAS and confidence interval estimation of QTLs were used to reveal the genetic architecture of wool traits. Six QTLs were detected with phenotypic variation contribution ranging from 0.42% to 7.50%. Gene-level mapping implicated FGF10 associated with fiber growth and diameter, which supported previous function research on fibroblast growth factor family in other species and provided genetic information for wool rabbit breeding. We suggest LCS as a cost-effective alternative for assessing common variants. GWAS combined with LCS can excavate QTLs and fine-map genes associated with quantitative traits. This study provides a powerful analysis mentality for investigating complex traits, which lays the foundation for genomic breeding.

genetics↗

bioRxiv2021

Chitin and cuticle proteins form the cuticular layer in the spinning duct of silk-spinning arthropods

Chitin is found in the exoskeleton and peritrophic matrix of arthropods, but recent studies have also identified chitin in the spinning duct of silk-spinning arthropods. Here, we report the presence and function of chitin and cuticle proteins ASSCP1 and ASSCP2 in the spinning duct of silkworms. We show that chitin and these proteins are co-located in the cuticular layer of the spinning duct. Ultrastructural analysis indicates that the cuticular layer has a multilayer structure by layered stacking of the chitin laminae. After knocking down ASSCP1 and ASSCP2, the fine structure of this layer was disrupted, which had negative impacts on the mechanical properties of silk. This work clarifies the function of chitin in the spinning duct of silk-spinning arthropods. Chitin and cuticle proteins are the main components of the hard and rigid cuticular layer, providing the shearing stress during silk fibrillogenesis and regulating the final mechanical properties of silk.

molecular biology↗

bioRxiv2021

Precise, 3-D optogenetic control of the diameter of single arterioles

Modulation of brain arteriole diameter is critical for maintaining cerebral blood pressure and controlling regional hyperemia during neural activity. However, studies of hemodynamic function in health and disease have lacked a method to control arteriole diameter independently with high spatiotemporal resolution. Here, we describe an all-optical approach to manipulate and monitor brain arteriole contractility in 3-dimensions using combined in vivo two-photon optogenetics and imaging. The expression of the red-shifted excitatory opsin, ReaChR, in vascular smooth muscle cells enabled rapid and repeated vasoconstriction controlled by brief light pulses. Two-photon activation of ReaChR using a spatial light modulator produced highly localized constrictions when targeted to individual arterioles within the neocortex. We demonstrate the utility of this method for examining arteriole contractile dynamics and creating transient focal blood flow reductions. Additionally, we show that optogenetic constriction can be used to reshape vasodilatory responses to sensory stimulation, providing a valuable tool to dissociate blood flow changes from neural activity.

neuroscience↗

bioRxiv2020

Functional dissection of neural circuitry using a genetic reporter for fMRI

The complex connectivity of the mammalian brain underlies its function, but understanding how interconnected brain regions interact in neural processing remains a formidable challenge. Here we address this problem by introducing a genetic probe that permits selective functional imaging of neural circuit elements defined by their synaptic interrelationships throughout the brain. The probe is an engineered enzyme that transduces cytosolic calcium dynamics of probe-expressing cells into localized hemodynamic responses that can be selectively visualized by functional magnetic resonance imaging. Using a viral vector that undergoes retrograde transport, we apply the probe to characterize a brain-wide network of monosynaptic inputs to the striatum activated in a deep brain stimulation paradigm in rats. The results reveal engagement of surprisingly diverse projection sources and inform an integrated model of striatal function relevant to reward behavior and therapeutic neurostimulation approaches. Our work thus establishes a potent strategy for mechanistic analysis of distributed neural systems.

neuroscience↗

bioRxiv2020

ssc-micorRNA-132 suppresses the Clostridium perfringens beta2 toxin induced inflammation and apoptosis of IPEC-J2 cells via targeting DACH1

Clostridium perfringens (C. perfringens) beta2 (CPB2) is the main virulence factor secreted from C. perfringens type C, which caused diarrhea characterized by high mortality in pig, especially newborn piglets. Our previous research found that ssc-miR-132 displayed decreased expression in piglets diarrhea after infected with C. perfringens type C compared with normal piglets. We speculated that ssc-miR-132 may play an important role in the diarrhea. However, the function of ssc-miR-132 in the diarrhea is limited. Thus, we overexpressed and knocked down ssc-miR-132 in intestinal porcine epithelial (IPEC-J2) cells, and then treated the cells with recombinant CPB2 (rCPB2) toxin (20 g/mL). Our results showed that ssc-miR-132 was significantly decreased after treated with rCPB2 toxin. In addition, overexpression of ssc-miR-132 reduced the expression of lactate dehydrogenase (LDH) and tumor necrosis factor (TNF-), interleukin-6 (IL-6) and interleukin-8 (IL-8) caused by rCPB2 toxin. The CCK8, Edu and TUNEL staining showed that overexpression of ssc-miR-132 weakened the inhibition of rCPB2 toxin on cell proliferation and reduced the promotion of cell apoptosis; while inhibition of ssc-miR-132 had opposite results. The dual luciferase experiment showed that dachshund family transcription factor 1 (DACH1) was the target gene of ssc-miR-132. Silencing DACH1 was consistent with the results of overexpression of ssc-miR-132, and reversed the apoptosis and inflammation caused by rCPB2 toxin. Overexpression of DACH1 weakened the role of ssc-miR-132 in rCPB2 toxin -induced inflammation and apoptosis. In summary, ssc-miR-132 inhibited rCPB2 toxin-induced apoptosis and inflammation in IPEC-J2 cells by targeting DACH1.

cell biology↗

bioRxiv2020

Dietary S. maltophilia promotes fat storage by enhancing lipogenesis and ER-LD contacts in C. elegans

Dietary and symbiotic bacteria can exert powerful influence on metazoan lipid metabolism. Here, we demonstrate that feeding Caenorhabditis elegans (C. elegans) with the opportunistic pathogenic bacteria Stenotrophomonas maltophilia (S. maltophilia) retards growth and promotes excessive fat storage. Gene expression analysis reveals that dietary S. maltophilia induces a lipogenic transcriptional response that includes the SREBP ortholog SBP-1, and fatty acid desaturases FAT-6 and FAT-7. Live imaging and ultrastructural analysis suggest that excess fat is stored in greatly expanded lipid droplets (LDs), as a result of enhanced endoplasmic reticulum-LD interaction. We also report that loss of function mutations in cyp-35B1 or dpy-9 in C. elegans confers resistance to S. maltophilia. Our work delineates a new model for understanding microbial regulation of metazoan physiology.

cell biology↗

bioRxiv2020

Identification of a Micropeptide on Lipid Droplet That Mediates Lipid Storage and Insulin Sensitivity

Over the past decade, great progress in sequencing technologies and computational biology has revealed that the majority of the mammalian genome considered to be noncoding is rich in functional elements able to produce proteins. Many RNA molecules, mis-annotated as noncoding, actually harbor small open reading frames that are predicted to code for proteins. Some of those proteins have been verified to play critical roles in multiple biological processes. The lipid droplet (LD) is a unique cellular organelle, conserved from bacteria to humans, and is closely associated with cellular lipid metabolism and metabolic disorders. No noncoding RNA-coded proteins have been identified on LDs. Here, for the first time, we searched the organelle for their presence. After the enrichment of small proteins of LDs isolated from myoblasts, we used mass spectrometry coupled with our lab made protein database to identify LD-associated noncoding RNA-encoded proteins (LDANPs). A total of 15 new proteins were identified. One of them was studied further and termed LDANP1. LDANP1 was localized on LDs by imaging, cell fractionation, and immunogold labeling. Like LD resident proteins, LDANP1 was degraded by the proteasome. Using the CRISPR/Cas9-mediated genome editing technique, the endogenous expression of LDANP1 was validated. The stable expression of LDANP1 suppressed the accumulation of triacylglycerol in oleic acid treated myoblasts and inhibited the rescue of palmitate-inhibited insulin sensitivity by oleic acid. In summary, we report for the first time that translatable, nominally noncoding RNA-derived proteins, which are new and cannot be identified using current research methods, were associated with LDs and that among these, LDANP1 modulated lipid metabolism and insulin sensitivity. The discovery of noncoding RNA-encoded proteins on LDs paves a new way for the research of LDs and lipid metabolism.

cell biology↗

bioRxiv2020

Metabolomic markers of colorectal tumor with different clinicopathological features

BackgroundColorectal cancer (CRC) is the result of complex interactions between the tumors molecular profile and metabolites produced by its microenvironment. Despite recent studies identifying CRC molecular subtypes, a metabolic classification system is still lacking. We aimed to explore the distinct phenotypes and subtypes of CRC at the metabolic level. MethodsWe conducted an untargeted metabolomics analysis of 51 paired tumor tissues and adjacent mucosa using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. Multivariate analysis including principal component analysis, orthogonal partial least squares discriminant analysis and heat maps, univariate analysis, and pathway analysis were used to identify potential metabolic phenotypes of CRC. Unsupervised consensus clustering were used to identify robust metabolic subtypes, and evaluated their clinical relevance. ResultsA total of 173 metabolites (including nucleotides, carbohydrates, free fatty acids, and choline) were identified between CRC tumor tissue and adjacent mucosa. We found that lipid metabolism was closely related to the occurrence and progression of CRC and CRC tissues could be divided into three subtypes, and statistically significant correlations between different subtypes and clinical prognosis were observed. ConclusionsCRC tumor tissue exhibits distinct metabolic phenotypes. Metabolic differences between subtypes may provide a basis and direction for further clinical individualized treatment planning.

cancer biology↗

bioRxiv2020

redPATH: Reconstructing the Pseudo Development Time of Cell Lineages in Single-Cell RNA-Seq Data and Applications in Cancer

Recent advancement of single-cell RNA-seq technology facilitates the study of cell lineages in developmental processes as well as cancer. In this manuscript, we developed a computational method, called redPATH, to reconstruct the pseudo developmental time of cell lineages using a consensus asymmetric Hamiltonian path algorithm. Besides, we implemented a novel approach to visualize the trajectory development of cells and visualization methods to provide biological insights. We validated the performance of redPATH by segmenting different stages of cell development on multiple neural stem cell and cancerous datasets, as well as other single-cell transcriptome data. In particular, we identified a subpopulation of malignant glioma cells, which are stem cell-like. These cells express known proliferative markers such as GFAP (also identified ATP1A2, IGFBPL1, ALDOC) and remain silenced in quiescent markers such as ID3. Furthermore, MCL1 is identified as a significant gene that regulates cell apoptosis, and CSF1R confirms previous studies for re-programming macrophages to control tumor growth. In conclusion, redPATH is a comprehensive tool for analyzing single-cell RNA-Seq datasets along a pseudo developmental time. The software is available via http://github.com/tinglab/redPATH.

bioinformatics↗

bioRxiv2020

Inferring Multiple Metagenomic Association Networks based on Variation of Environmental Factors

Identifying significant biological relationships or patterns is central to many metagenomic studies. Methods that estimate association networks have been proposed for this purpose, but they assume that associations are static, neglecting the fact that relationships in a microbial ecosystem may vary with changes in environmental factors, which can result in inaccurate estimations. We propose a computational model, k-Lognormal-Dirichlet-Multinomial model (kLDM), which estimates multiple association networks that correspond to specific environmental conditions according to values of environmental factors (EFs), and simultaneously infers microbe-microbe and environmental factor-microbe associations for each network. We showed the effectiveness of kLDM on synthetic data, a colorectal cancer dataset, as well as the TARA Oceans and American Gut project datasets. The results showed that the widely used Spearmans rank correlation coefficient (SCC) performed much worse than other methods, indicating the importance of separating samples by environmental conditions. We compared cancer fecal samples with cancer-free samples, and our estimation showed fewer associations among microbes but stronger associations between specific bacteria such as five colorectal cancer (CRC)-associated OTUs, indicating gut microbe translocation in cancer patients. Some environmental-factor-dependent associations were found within marine eukaryotic community, and gut microbial heterogeneity of irritable bowel disease (IBD) patients was detected. Results demonstrated that kLDM could successfully unravel the underlying biological associations. In summary, our study presents a computational framework that can elucidate the complex associations within microbial ecosystems. The kLDM program, R, and python scripts, together with all experimental datasets are all accessible at Github (https://github.com/tinglab/kLDM.git).

bioinformatics↗