Biology subjects

Yan, G.

Publications and source records attributed to Yan, G..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Decoding region-level visual functions from invasive EEG monkey data

Decoding vision is an ambitious task as it aims to transform scalar brain activity into dynamic images with refined shapes, colors and movements. In familiar environments, the brain may trigger activity that resembles specific pattern, thereby facilitating decoding. Can an artificial neural network (ANN) decipher such latent patterns? Here, we explore this question using invasive electroencephalography data from monkeys. By decoding multiregion brain activity, ANN effectively captures individual regions functional roles as a consequence of minimizing visual errors. For example, ANN recognizes that regions V4 and LIP are involved in visual color and shape processing while MT predominantly handles visual motion, aligning with regional visual functions evident in the brain. ANN likely reconstructs vision by seizing hidden spike patterns, representing stimuli distinctly in a two-dimensional plane. Furthermore, during the encoding process of transforming visual stimuli into neuronal activity, optimal performance is achieved in regions closely associated with vision processing.

neuroscience↗

bioRxiv2024

PRMT5 deficiency disturbs Nur77 methylation to inhibit endometrial stromal cell differentiation in recurrent implantation failure

Various posttranslational modifications (PTMs) have been implicated in endometrial stromal cell (EnSC) differentiation, but the potential role of PTM crosstalk has not been identified. Here, we report that protein arginine methyltransferase 5 (PRMT5) is indispensable for human endometrial decidualization, functioning as a key regulator of decidualization defect in recurrent implantation failure (RIF) patients. Uterine-selective deletion of Prmt5 led to defective embryo implantation in mice due to impaired EnSC decidualization. Mechanistically, we find that PRMT5 catalyzes symmetric dimethylation of orphan nuclear receptor Nur77 at arginine 346, which in turn promotes Nur77 nuclear localization and increases its transcriptional activity in EnSC. Moreover, we demonstrate that PRMT5-mediated Nur77 methylation antagonizes AKT-induced phosphorylation of Nur77 at serine 351 in the transition from proliferation to differentiation of EnSC and disruption of the balance between methylation and phosphorylation of Nur77 is essentially involved in the endometrium of RIF patients. Furthermore, by modulating the methylation-phosphorylation of Nur77 and its transcriptional activity, we rescued impaired decidualization in RIF, further highlighting the critical role of the PRMT5/AKT/Nur77 complex in uterine receptivity to embryo implantation.

cell biology↗

bioRxiv2023

Biosynthesis of the proteins containing neurotoxin β-N-methylamino-L-alanine in marine diatoms

Neurotoxin {beta}-N-methylamino-L-alanine (BMAA) has been deemed a pathogenic factor for human neurodegenerative diseases. It is an important issue to disclose the biosynthesis mechanism of BMAA in marine diatoms. In the present study, the iron (Fe) limitation (1/3 x Fe) was found to suppress the growth of diatoms but stimulate the production of BMAA-containing proteins, maximum 7.7 fold in Thalassiosira minima. Transcriptome analysis showed that energy metabolism, protein biosynthesis and carbon fixation functions were mainly affected by the Fe limitation in the diatom. Analysis of subcellular distribution of BMAA showed that BMAA-containing proteins were mainly detected in the endoplasmic reticulum and the Golgi apparatus. Combination results of the responses of the diatom to Fe deficiency and co-culture with cyanobacteria in our previous study, we speculate that cysteine embedded in peptide chains and methylamine produced by the diatom itself are possibly catalyzed by the cysteine synthase (cysK) to form the BMAA structure in situ. Spiked methylamine in culture media significantly stimulated the production of BMAA, and BMAA amounts were correlated with the expression of cysK gene in different diatoms. The reduced ubiquitination-mediated proteolysis and vesicle trafficking precision through the COPII system would aggravate the accumulation of BMAA-containing proteins in the diatom. Significance StatementWith the detection of neurotoxin BMAA in diverse marine diatoms, the pathogenic risk of BMAA has been further concerned to human neurodegenerative diseases such as Alzheimers disease. Interestingly, BMAA-containing proteins are the dominant forms of this neurotoxin in diatoms. It is a keystone issue to disclose the biosynthesis mechanism of BMAA in marine diatoms. We found Fe-limitation could stimulate the production of BMAA-containing proteins in diatoms and explored its biosynthesis using transcriptomics in this study. Results suggested that cysteine embedded in peptides and methylamine in cytoplasm were catalyzed by the cysteine synthase (cysK) to form BMAA. This study hints that the biosynthesis of BMAA would be improved by the worldwide prevalence of iron deficiency in the coastal waters.

biochemistry↗

bioRxiv2023

Site Effects in Multisite Fetal Brain MRI: Morphological Insights into Early Brain Development

BackgroundMultisite MRI studies have become prevalent given their advantage in revealing reliable biological or clinical findings. Adult and adolescent multisite studies have demonstrated inevitable site-related non-biological effects that introduce bias. However, the site effect on fetal brain MRI remains unknown. PurposeTo identify crucial acquisition factors affecting fetal brain structural measurements and developmental patterns, while assessing the effectiveness of existing harmonization methods in mitigating site effects. Materials and MethodsBetween May 2017 and March 2022, T2-weighted fast spin-echo sequences in-utero MRI were performed in healthy fetuses from prospectively recruited pregnant volunteers on four different scanners at four sites. A generalized additive model (GAM) was used to quantitatively assess site effects, including field strength (FS), manufacture (M), in-plane resolution (R), and slice thickness (ST), on subcortical volume and cortical morphological measurements, including cortical thickness, curvature, and sulcal depth. Growth models were selected to elucidate developmental trajectories of these morphological measurements. Welchs test was performed to evaluate the influence of site effects on developmental trajectories. ComBat-GAM harmonization method was applied to mitigate site-related biases. ResultsThe final analytic sample consisted of 340 MRI scans from 218 fetuses (mean gestational age, 30.1 weeks {+/-} 4.4 [range, 21.7-40 weeks]). GAM results showed that low FS and low spatial resolution led to overestimations in selected brain regions of subcortical volumes and cortical morphological measurements, and cortical measurements were more susceptible to site effects than subcortical volumes. Only the peak cortical thickness in developmental trajectories was significantly influenced by the effects of FS and R. Notably, ComBat-GAM harmonization effectively removed site effects while preserving developmental patterns. ConclusionOur findings pinpointed the key acquisition factors in in-utero fetal brain MRI and underscored the necessity of data harmonization when pooling multisite data for fetal brain morphology investigations.

bioengineering↗

bioRxiv2023

Benchmarking computational methods to identify spatially variable genes and peaks

Spatially resolved transcriptomics offers unprecedented insight by enabling the profiling of gene expression within the intact spatial context of cells, effectively adding a new and essential dimension to data interpretation. To efficiently detect spatial structure of interest, an essential step in analyzing such data involves identifying spatially variable genes. Despite researchers having developed several computational methods to accomplish this task, the lack of a comprehensive benchmark evaluating their performance remains a considerable gap in the field. Here, we present a systematic evaluation of 14 methods using 60 simulated datasets generated by four different simulation strategies, 12 real-world transcriptomics, and three spatial ATAC-seq datasets. We find that spatialDE2 consistently outperforms the other benchmarked methods, and Morans I achieves competitive performance in different experimental settings. Moreover, our results reveal that more specialized algorithms are needed to identify spatially variable peaks.

bioinformatics↗

bioRxiv2023

Aalbo1200: global genetic differentiation and variability of the mosquito Aedes albopictus

The mosquito Aedes albopictus transmits human viruses including dengue and chikungunya and is an extremely successful invasive species expanding into new regions of the world. New tools are needed to complement existing tools to help monitor and control this species. Genomic resources are improving for this species including genome reference sequences, and whole genome sequencing data will help to catalog genetic diversity in this species and further enable genetic analysis. We collected populations of Ae. albopictus from throughout its distribution and generated whole genome sequencing data from population samples. These data will be used to address a number of basic and applied questions for this species. Here, we show genetic differentiation patterns among the tropical and temperate forms, as well as finer scale genetic clustering at the regional and population scale. These data and results will be a valuable resource for further study and tool development for this species.

evolutionary biology↗

bioRxiv2023

A seven-sex species recognizes self and non-self mating-type via a novel protein complex

Although most species have two sexes, multisexual (or multi-mating type) species are also widespread. However, it is unclear how mating-type recognition is achieved at the molecular level in multisexual species. The unicellular ciliate Tetrahymena thermophila has seven mating types, which are determined by the MTA and MTB proteins. In this study, we found that both proteins are essential for cells to send or receive complete mating-type information, and transmission of the mating-type signal requires both proteins to be expressed in the same cell. We found that MTA and MTB form a mating-type recognition complex that localizes to the plasma membrane, but not to the cilia. Stimulation experiments showed that the mating-type-specific regions of MTA and MTB mediate both self- and non-self-recognition, indicating that T. thermophila uses a dual approach to achieve mating-type recognition. Our results suggest that MTA and MTB form an elaborate multifunctional protein complex that can identify cells of both self and non-self mating types in order to inhibit or activate mating, respectively. Impact statementA giant multifunctional protein complex mediates mating-type recognition through a non-ligand-receptor mechanism in a multisexual species.

genetics↗

bioRxiv2023

Estrogen prevents age-dependent beige adipogenesis failure through NAMPT-controlled ER stress pathway

Thermogenic beige adipocytes are recognized as potential therapeutic targets for combating metabolic diseases. However, the metabolic advantages they offer are compromised with aging. Here, we show that treating mice with estrogen (E2), a hormone that decreases with age, to mice can counteract the aging- related decline in beige adipocyte formation when subjected to cold, while concurrently enhancing energy expenditure and improving glucose tolerance. Mechanistically, we find that nicotinamide phosphoribosyltranferase (NAMPT) plays a pivotal role in facilitating the formation of E2-induced beige adipocytes, which subsequently suppresses the onset of age-related ER stress. Furthermore, we found that targeting NAMPT signaling, either genetically or pharmacologically, can restore the formation of beige adipocytes by increasing the number of perivascular adipocyte progenitor cells. Conversely, the absence of NAMPT signaling prevents this process. In conclusion, our findings shed light on the mechanisms governing the age-dependent impairment of beige adipocyte formation and underscore the E2-NAMPT controlled ER stress as a key regulator of this process. HighlightsO_LIEstrogen restores beige adipocyte failure along with improved energy metabolism in old mice. C_LIO_LIEstrogen enhances the thermogenic gene program by mitigating age-induced ER stress. C_LIO_LIEstrogen enhances the beige adipogenesis derived from SMA+ APCs. C_LIO_LIInhibiting the NAMPT signaling pathway abolishes estrogen-promoted beige adipogenesis. C_LI

physiology↗

bioRxiv2023

Modeling of mitochondrial genetic polymorphisms reveals induction of heteroplasmy by pleiotropic disease locus MT:10398A>G

Mitochondrial (MT) dysfunction has been associated with several neurodegenerative diseases including Alzheimers disease (AD). While MT-copy number differences have been implicated in AD, the effect of MT heteroplasmy on AD has not been well characterized. Here, we analyzed over 1,800 whole genome sequencing data from four AD cohorts in seven different tissue types to determine the extent of MT heteroplasmy present. While MT-heteroplasmy was present throughout the entire MT genome for blood samples, we detected MT-heteroplasmy only within the MT control region for brain samples. We observed that an MT variant 10398A>G (rs2853826) was significantly associated with overall MT-heteroplasmy in brain tissue while also being linked with the largest number of distinct disease phenotypes of all annotated MT variants in MitoMap. Using gene-expression data from our brain samples, our modeling discovered several gene networks involved in mitochondrial respiratory chain and Complex I function associated with 10398A>G. The variant was also found to be an expression quantitative trait loci (eQTL) for the gene MT-ND3. We further characterized the effect of 10398A>G by phenotyping a population of lymphoblastoid cell-lines (LCLs) with and without the variant allele. Examination of RNA sequence data from these LCLs reveal that 10398A>G was an eQTL for MT-ND4. We also observed in LCLs that 10398A>G was significantly associated with overall MT-heteroplasmy within the MT control region, confirming the initial findings observed in post-mortem brain tissue. These results provide novel evidence linking MT SNPs with MT heteroplasmy and open novel avenues for the investigation of pathomechanisms that are driven by this pleiotropic disease associated loci.

genomics↗

bioRxiv2023

Targeting CD301+ macrophage inhibits endometrial fibrosis and improves pregnancy outcome

Macrophages are a key and heterogeneous cell population involved in endometrial repair and regeneration during the menstrual cycle, but their role in the development of intrauterine adhesion (IUA) and sequential endometrial fibrosis remains unclear. Here, we reported that CD301+ macrophages were significantly increased and showed their most active interaction with profibrotic cells in the endometria of IUA patients compared with the normal endometria by single-cell RNA sequencing, bulk RNA sequencing and experimental verification. Increasing CD301+ macrophages promoted the differentiation of endometrial stromal cells into myofibroblasts and resulted in extracellular matrix accumulation, which destroyed the physiological architecture of endometrial tissue, drove endometrial fibrosis and ultimately led to female infertility or adverse pregnancy outcomes. Mechanistically, CD301+ macrophages secreted GAS6 to activate the AXL/NF-{kappa}B pathway, up-regulating the profibrotic protein synthesis. Targeted deletion of CD301+ macrophages or inhibition of AXL by Bemcentinib blunted the pathology and improved the outcomes of pregnancy in mice, supporting the therapeutic potential of targeting CD301+ macrophages for treating endometrial fibrosis.

immunology↗

bioRxiv2022

Cdkn2a regulates beige fat maintenance through BECN1-mediated autophagy

A potential therapeutic target to curb the obesity and diabetes epidemic is thermogenic beige adipocytes. However, beige adipocytes quickly transition into white adipocytes upon removing stimuli. Here, we define the critical role of Cdkn2a as a molecular pedal for the beige-to-white transition. Beige adipocytes lacking Cdkn2a exhibit prolonged lifespan, and mice are more resistant to diet-induced obesity, along with enhanced energy expenditure and improved glucose tolerance. Mechanistic studies demonstrate that Cdkn2a promotes the expression and activity of BECN1 by directly binding to its mRNA and its negative regulator BCL2L1, activating autophagy and accelerating the beige-to-white transition. Notably, reactivating autophagy by pharmacological or genetic methods abolishes beige adipocyte maintenance induced by Cdkn2a-ablation. Furthermore, hyperactive BECN1 alone significantly accelerates the beige-to-white transition. Collectively, these findings show that Cdkn2a-mediated autophagy serves as a brake system for beige adipocyte maintenance and is a highly promising target for anti-obesity and anti-diabetes therapy. HighlightsO_LICdkn2a ablation promotes beige fat maintenance and ameliorates diet-induced obesity C_LIO_LILoss of Cdkn2a retains beige adipocytes by inhibiting BECN1-mediated autophagy C_LIO_LICdkn2a modulates BECN1 by binding to its mRNA and its inhibitor BCL2L1, respectively C_LIO_LIHyperactive BECN1 is sufficient to accelerate the beige-to-white transition C_LI

cell biology↗

bioRxiv2022

Mapping potential malaria vector larval habitats for larval source management: Introduction to multi-model ensembling approaches

Mosquito larval source management (LSM) is a viable supplement to the currently implemented first-line malaria control tools for use under certain conditions for malaria control and elimination. Implementation of larval source management requires a carefully designed strategy and effective planning. Identification and mapping of larval sources is a prerequisite. Ensemble modeling is increasingly used for prediction modeling, but it lacks standard procedures. We proposed a detailed framework to predict potential malaria vector larval habitats using ensemble modeling, which includes selection of models, ensembling method and predictors; evaluation of variable importance; prediction of potential larval habitats; and assessment of prediction uncertainty. The models were built and validated based on multi-site, multi-year field observations and climatic/environmental variables. Model performance was tested using independent multi-site, multi-year field observations. Overall, we found that the ensembled model predicted larval habitats with about 20% more accuracy than the average of the individual models ensembled. Key larval habitat predictors were elevation, geomorphon class, and precipitation 2 months prior. Mapped distributions of potential malaria vector larval habitats showed different prediction errors in different ecological settings. This is the first study to provide a detailed framework for the process of multi-model ensemble modeling. Mapping of potential habitats will be helpful in LSM planning. Authors summaryMosquito larval source management (LSM) is a viable supplement to the currently implemented first-line malaria control tools. Implementation of LSM requires a carefully designed strategy and effective planning. Identification and mapping of larval sources is a prerequisite. Ensemble modeling is increasingly used for prediction modeling, but it lacks standard procedures. We proposed a detailed framework for such a process, including selection of models, ensembling methods and predictors; evaluation of variable importance; and assessment of prediction uncertainty. We used predictions of potential malaria vector larval habitats as an example to demonstrate how the procedure works, specifically, we used multi-site multi-year field observations to build and validate the model, and model performance was further tested using independent multi-site multi-year field observations - this training-validation-testing is often missing from previous studies. The proposed ensemble modeling procedure provides a framework for similar biological studies.

ecology↗

bioRxiv2022

A unified framework of realistic in silico data generation and statistical model inference for single-cell and spatial omics

In the single-cell and spatial omics field, computational challenges include method benchmarking, data interpretation, and in silico data generation. To address these challenges, we propose an all-in-one statistical simulator, scDesign3, to generate realistic single-cell and spatial omics data, including various cell states, experimental designs, and feature modalities, by learning interpretable parameters from real datasets. Furthermore, using a unified probabilistic model for single-cell and spatial omics data, scDesign3 can infer biologically meaningful parameters, assess the goodness-of-fit of inferred cell clusters, trajectories, and spatial locations, and generate in silico negative and positive controls for benchmarking computational tools.

bioinformatics↗

bioRxiv2022

Vimentin intermediate filaments provide structural stability to the mammalian Golgi apparatus

The Golgi apparatus comprises a connected ribbon of stacked cisternal membranes localized to the perinuclear region of most vertebrate cells. The position and morphology of this organelle depends upon interactions with microtubules and the actin cytoskeleton. In contrast, we know relatively little about the relationship of the Golgi apparatus with intermediate filaments. In this study we show that the Golgi is in close physical proximity to vimentin intermediate filaments (IFs) in cultured mouse and human cells. We also show that the trans-Golgi network coiled-coil protein GORAB can physically associate with IFs. Although loss of vimentin and/or GORAB does not have major effects upon Golgi morphology at steady-state, the Golgi undergoes more rapid disassembly upon chemical disruption with the drug brefeldin A, and slower reassembly upon drug washout, in vimentin knockout cells. Moreover, loss of vimentin causes reduced Golgi ribbon integrity when cells are cultured on high stiffness hydrogels, which is exacerbated by loss of GORAB. These results indicate that vimentin IFs contribute to the structural stability of the Golgi apparatus, and suggest a role for GORAB in this process.

cell biology↗

bioRxiv2022

scReadSim: a single-cell multi-omics read simulator

Benchmarking single-cell RNA-seq (scRNA-seq) and single-cell ATAC-seq (scATAC-seq) computational tools demands simulators to generate realistic sequencing reads. However, none of the few read simulators aim to mimic real data. To fill this gap, we introduce scReadSim, a single-cell RNA-seq and ATAC-seq read simulator that allows user-specified ground truths and generates synthetic sequencing reads (in FASTQ and BAM formats) by mimicking real data. At both read-sequence and read-count levels, scReadSim mimics real scRNA-seq and scATAC-seq data. Moreover, scReadSim provides ground truths, including unique molecular identifier counts for scRNA-seq and open chromatin regions for scATAC-seq. In particular, scReadSim allows users to design cell-type-specific ground-truth open chromatin regions for scATAC-seq data generation. In benchmark applications of scReadSim, we show that cell-ranger is a preferred scRNA-seq UMI deduplication tool, and HMMRATAC and MACS3 achieve top performance in scATAC-seq peak calling.

bioinformatics↗

bioRxiv2022

Sequential functional differentiation of luminal epithelial cells regulated by maternal and embryonic signaling in the mouse endometrium

Embryo implantation requires temporospatial maternal-embryo dialog to regulate the interactions between an activated blastocyst and a receptive endometrium; however, the details of the related cell-specific coordination is largely unknown because of the cellular complexity and dynamic developmental processes of both the embryo and endometrium during peri-implantation. By comparing single-cell RNA (scRNA) data obtained from entire uteri of pregnant and pseudo-pregnant mice with embryos that were in the oviduct (dpc2.5 days post-coitum [dpc]) or had entered the uterus (after 3.5 dpc), we found a maternal estrogen and progesterone signaling-dependent functional differentiation process in which progesterone induced estrogen-responsive luminal epithelial cells to differentiate into two new types of epithelial cells: adhesion epithelial cells (AECs) and supporting epithelial cells (SECs) on 2.5 dpc. In addition to maternal signaling data, the uterine scRNA and corresponding embryo bulk sequencing data were obtained, and analyses revealed that embryonic Pdgfa and Efna3/4 signaling activated AECs and SECs, enhancing the attachment of embryos to the endometrium after implantation. Specifically, embryonic signaling induced additional transformation of AECs by preventing adjacent AECs, but not AECs away from the embryo in the implantation chamber, from undergoing apoptosis. Furthermore, we demonstrated that epithelial cell differentiation and related regulatory signaling were largely conserved in humans and mice. In the human endometrium, developmental defects of SOX9-positive epithelial cells similar to luminal epithelial cells were related to thin endometrium. Our work provides comprehensive and systematic information on endometrial luminal epithelial cell development directed by maternal and embryonic signaling, which is important for endometrial receptivity and embryo implantation.

cell biology↗

bioRxiv2022

Temporal and spatial dynamics mapping reveals follicle development regulated by different stromal cell populations

Follicle development is a complex dynamic process. The follicles are encapsulated in the stroma, and once the follicle develops, the follicle moves from the cortex to the medulla and finally to the cortex to ovulate in the process of continuous growth. Many of these processes cannot be explained with the follicle alone. Through single-cell and spatial transcriptome sequencing at key time points of follicular development in mice after birth, we found that ovarian stromal cells are not only one of the main cell groups that make up the ovary but that their cell population and spatial location are also closely related to follicular development. Through analysis of cell communication, it was found that ovarian stromal cells were the main transmitters of intercellular communication, and many of the signals they sent were received by granulosa cells and oocytes to participate in follicle development. Ovarian stromal cells are not a homogeneous cell population. We combined single cell types with their spatial location information to divide ovarian stromal cells into four types, namely, structural stromal cells, perifollicular stromal cells, stromal progenitor cells, and steroidogenic stromal cells, each of which plays a different function in follicle development. Indepth studies of the different spatial locations and different types of stromal cells will expand our understanding of follicle development dynamics, leading to new targets and novel approaches for the treatment of ovarian-related diseases.

developmental biology↗

bioRxiv2022

De-heterogeneity of the eukaryotic viral reference database (EVRD) improves the accuracy and efficiency of viromic analysis

Widespread in public databases, the notorious contamination in virus reference databases often leads to confusing even wrong conclusions in applications like viral disease diagnosis and viromic analysis, highlighting the need of a high-quality database. Here, we report the comprehensive scrutiny and the purification of the largest viral sequence collections of GenBank and UniProt by detection and characterization of heterogeneous sequences (HGSs). A total of 766 nucleotide- and 276 amino acid-HGSs were determined with length up to 6,605 bp, which were widely distributed in 39 families, with many involving highly public health-related viruses, such as hepatitis C virus, Crimea-Congo hemorrhagic fever virus and filovirus. Majority of these HGSs are sequences of a wide range of hosts including humans, with the rest resulting from vectors, misclassification and laboratory components. However, these HGSs cannot be simply considered as exotic contaminants, since part of which are resultants of natural occurrence or artificial engineering of the viruses. Nevertheless, they significantly disturb the genomic analysis, and hence were deleted from the database. A further augmentation was implemented with addition of the risk and vaccine sequences, which finally results in a high-quality eukaryotic virus reference database (EVRD). EVRD showed higher accuracy and less time-consuming without coverage compromise by reducing false positives than other integrated databases in viromic analysis. EVRD is freely accessible with favorable application in viral disease diagnosis, taxonomic clustering, viromic analysis and novel virus detection.

microbiology↗