Biology subjects

Chen, J.-Y.

Publications and source records attributed to Chen, J.-Y..

13 recordsLinked to original sources

bioRxiv2026

Postsynaptic TAK1-GluN2B axis supports hippocampal synaptic integrity and cognitive function during aging

Transforming growth factor {beta}-activated kinase 1 (TAK1) is a serine/threonine kinase best known for its roles in immune and stress-response signaling, yet its physiological function in mature neurons remains poorly understood. Here we identify neuronal TAK1 as a regulator of excitatory synaptic integrity, hippocampal plasticity and memory. Conditional reduction of TAK1 in forebrain excitatory neurons impaired short- and long-term memory and was accompanied by attenuated long-term potentiation in the hippocampus. At the cellular level, TAK1 deficiency reduced dendritic spine density and suppressed excitatory synaptic transmission, whereas genetic or pharmacological disruption of TAK1 kinase activity recapitulated these synaptic deficits. Mechanistically, TAK1 localized to the postsynaptic compartment of excitatory synapses and associated with PSD-95. Phosphoproteomic analysis of isolated postsynaptic density fractions revealed coordinated changes in synaptic phosphorylation following TAK1 reduction, including decreased phosphorylation of the NMDA receptor subunit GluN2B at serine 920. Analyses of phosphodeficient and phosphomimetic GluN2B mutants supported a role for S920 phosphorylation downstream of TAK1 in maintaining dendritic spine density, excitatory synaptic transmission and spontaneous synaptic calcium activity. Notably, synaptic TAK1 level was reduced in the aged hippocampus. Re-expressing neuronal TAK1 in aged mice increased dendritic spine density, enhanced hippocampal synaptic plasticity, and improved memory performance. Together, these findings define a postsynaptic TAK1-GluN2B signaling axis that supports excitatory synaptic function and suggest that reduced synaptic TAK1 signaling may contribute to hippocampal vulnerability during aging.

neuroscience↗

bioRxiv2024

Host-derived Lactobacillus plantarum alleviates hyperuricemia by improving gut microbial community and hydrolase-mediated degradation of purine nucleosides

AbstractGut microbiota has been considered to be associated with the development of hyperuricemia (HUA) and gout. Some prebiotics from different sources had the potential alleviation function in HUA. However, whether host-derived potential probiotics, like Lactobacillus, from the gut of HUA animals could prevent the development of HUA is still uncertain. In this study, we established a HUA geese model and isolated a Lactobacillus plantarum strain, SQ001, from the cecum of HUA geese. Nucleoside co-culture and metabolomics analyses revealed that L. plantarum SQ001 is involved in the absorption and hydrolysis of nucleosides. Whole genome analysis showed there are four genes related with nucleosides hydrolysis in L. plantarum SQ001. The function of iunH, a nucleoside hydrolase gene, was further confirmed by heterologous expression and knockout assays. Oral administration of L. plantarum SQ001 in HUA geese models upregulated the Lactobacillus abundance and reduced serum uric acid (UA) levels. Likewise, in mouse models, L. plantarum SQ001 increased the L. plantarum abundance and lowered serum UA levels by reducing hepatic UA synthesis protein XO and renal UA reabsorption protein GLUT9 expression, while increasing renal UA excretion protein ABCG2 expression. Our findings demonstrated that host-derived probiotics from geese could alleviate gut microbe dysbiosis and HUA in its host and mouse model. This study provides insights into the potential probiotic role of Lactobacillus plantarum in HUA or gout therapy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=83 SRC="FIGDIR/small/606206v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@698e7eorg.highwire.dtl.DTLVardef@a2091org.highwire.dtl.DTLVardef@e0348aorg.highwire.dtl.DTLVardef@19958ad_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2023

Genetic diversity of domestic cat hepadnavirus in Taiwan

Domestic cat hepadnavirus (DCH) is an infectious disease associated with chronic hepatitis in cats, suggesting a similarity with hepatitis B virus infection in humans. Since its first identification in Australia in 2018, DCH has been reported in several countries with varying prevalence rates, but its prevalence in Taiwan has not yet been investigated. Here, we aimed to identify the presence and prevalence of DCH infections in Taiwan. Among 71 samples tested, eight (11.27%) were positive for DCH. Of these positive cases, three cats had elevated levels of alanine transaminase (ALT) and aspartate transaminase (AST), suggesting an association between DCH infection and chronic hepatitis. Four DCH-positive samples were also tested for feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) co-infection, one (25%) was positive for FIV while none for FeLV (0%). In addition, we performed whole genome sequencing of six samples to determine the viral genome sequences. Phylogenetic analyses identified a distinct lineage compared with previously reported sequences. Considering the recent findings suggesting the potential risk of DCH for interspecies or zoonotic transmission, this study suggests the importance of continuous surveillance of DCH and further research to elucidate the pathophysiology and transmission route of DCH.

genetics↗

bioRxiv2023

Microhomology-Mediated Circular DNA Formation from Oligonucleosomal Fragments During Spermatogenesis

The landscape of extrachromosomal circular DNA (eccDNA) during mammalian spermatogenesis, as well as the biogenesis mechanism remains to be explored. Here, we revealed widespread eccDNA formation in human sperms and mouse spermatogenesis. We noted that germline eccDNAs are derived from oligonucleosomal DNA fragmentation in cells likely undergoing cell death, providing a potential new way for quality assessment of human sperms. Interestingly, small-sized eccDNAs are associated with euchromatin, while large-sized ones are preferentially generated from heterochromatin. By comparing sperm eccDNAs with meiotic recombination hotspots and structural variations, we found that they are barely associated with de novo germline deletions. We further developed a bioinformatics pipeline to achieve nucleotide-resolution eccDNA detection even with the presence of microhomologous sequences that interfere with precise break-point identification. Empowered by our method, we provided strong evidence to show that microhomology-mediated end joining is the major eccDNA biogenesis mechanism. Together, our results shed lights on eccDNA biogenesis mechanism in mammalian germline cells.

genomics↗

bioRxiv2022

Cell-Sized Lipid Vesicles as Artificial Antigen-Presenting Cells for Antigen-Specific T Cell Activation

In this study, efficient T cell activation is demonstrated using cell-sized artificial antigen-presenting cells (aAPCs) with protein-conjugated bilayer lipid membranes that mimic biological cell membranes. The highly uniform aAPCs are generated by a facile method based on standard droplet microfluidic devices. These aAPCs are able to activate the T cells in peripheral blood mononuclear cells (PBMCs), showing a 28-fold increase in IFN{gamma} secretion, a 233-fold increase in antigen-specific CD8 T cells expansion, and a 16-fold increase of CD4 T cell expansion. The aAPCs do not require repetitive boosting or additional stimulants and can function at a relatively low aAPC-to-T cell ratio (1-to-17). The research presents strong evidence that the surface fluidity and size of the aAPCs are critical to the effective formation of immune synapses essential for T cell activation. The findings demonstrate that the microfluidic-generated aAPCs can be instrumental in investigating the physiological conditions and mechanisms for T cell activation. Finally, this method demonstrates the feasibility of customizable aAPCs for a cost-effective off-the-shelf approach to immunotherapy.

bioengineering↗

bioRxiv2022

Multi range ERK responses shape the proliferative trajectory of single cells following oncogene induced senescence

Oncogene-induced senescence (OIS) is a phenomenon in which aberrant oncogene expression causes non-transformed cells to enter a non-proliferative state. Cells undergoing OIS display phenotypic heterogeneity, with some cells senescing and others remaining proliferative. The causes of the heterogeneity remain poorly understood. We studied the sources of heterogeneity in the responses of human epithelial cells to oncogenic BRAFV600E expression. We found that a narrow expression range of BRAFV600E generated a wide range of activities of its downstream effector ERK. In population-level and single cell assays, ERK activity displayed a non-monotonic relationship to proliferation, with intermediate ERK activities leading to maximal proliferation. We profiled gene expression across a range of ERK activities over time and characterized four distinct ERK response classes, which we propose act in concert to generate the unique ERK-proliferation response. Altogether, our studies mapped the input-output relationships between ERK activity and proliferation providing important insights into how heterogeneity can be generated during OIS.

systems biology↗

bioRxiv2022

Massive Horizontal Gene Transfer in Amphioxus Illuminates the Early Evolution of Deuterostomes

Amphioxus is considered the best-known living proxy to the chordate ancestor and an irreplaceable model organism for evolutionary studies of chordates and deuterostomes. In this study, a high-quality genome of the Beihai amphioxus, Branchiostoma belcheri beihai, was de novo assembled and annotated. Within four amphioxus genomes, twenty-eight groups of gene novelties were identified, revealing new genes that lack homologs in non-deuterostome metazoa, but share unexpectedly high similarities with those from non-metazoan species. These gene innovation events have played roles in amphioxus adaptations, including innate immunity responses, glycolysis, and regulation of calcium balance. The gene novelties related to innate immunity, such as a group of lipoxygenases and a DEAD-box helicase, boosted amphioxus immune responses. The novel genes for alcohol dehydrogenase and ferredoxin could aid in the glycolysis of amphioxus. A proximally arrayed cluster of EF-hand calcium-binding protein genes were identified to resemble those of bacteria. The copy number of this gene cluster was negatively correlated to the sea salinity of the collection region, suggesting that it may enhance their survival at different calcium concentrations. This comprehensive study collectively reveals insights into adaptive evolution of cephalochordates and provides valuable resources for research on early evolution of deuterostomes.

evolutionary biology↗

bioRxiv2022

Systematic Evaluation of Different R-loop Mapping Methods: Achieving Consensus, Resolving Discrepancies and Uncovering Distinct Types of RNA:DNA Hybrids

R-loop, a three-stranded nucleic acid structure, has been recognized to play pivotal roles in critical physiological and pathological processes. Multiple technologies have been developed to profile R-loops genome-wide, but the existing data suffer from major discrepancies on determining genuine R-loop localization and its biological functions. Here, we experimentally and computationally evaluate eight representative R-loop mapping technologies, and reveal inherent biases and artifacts of individual technologies as key sources of discrepancies. Analyzing signals detected with different R-loop mapping strategies, we note that genuine R-loops predominately form at gene promoter regions, whereas most signals in gene body likely result from structured RNAs as part of repeat-containing transcripts. Interestingly, our analysis also uncovers two classes of R-loops: The first class consists of typical R-loops where the single-stranded DNA binding protein RPA binds both the template and non-template strands. By contrast, the second class appears independent of Pol II-mediated transcription and is characterized by RPA binding only in the template strand. These two different classes of RNA:DNA hybrids in the genome suggest distinct biochemical activities involved in their formation and regulation. In sum, our findings will guide future use of suitable technology for specific experimental purposes and the interpretation of R-loop functions.

genomics↗

bioRxiv2022

Single-cell transcriptome landscape of zebrafish liver reveals hepatocytes and immune cell interactions in understanding nonalcoholic fatty liver disease

Zebrafish have emerged as an attractive animal model for studying nonalcoholic fatty liver disease (NAFLD). However, little is known about the cell types and intercellular interactions in zebrafish liver. Here, we established a liver atlas that consists of 10 cell types using single-cell RNA sequencing. By examining the heterogeneity of hepatocytes and analyzing the expression of NAFLD-associated genes in the specific cluster, we provide a potential target cell model to study NAFLD. Additionally, our analysis identified two distinct resident macrophages with inflammatory and noninflammatory functions and characterized the successive stepwise development of T cell subtypes in the liver. Importantly, we uncovered possible molecular mechanisms and revealed the central regulation of macrophages on target cells of fatty liver by analyzing the cellular interaction between hepatocytes and immune cells. Our data provide valuable information for future research on NAFLD in zebrafish.

immunology↗

bioRxiv2019

Sporadic ERK pulses drive non-genetic resistance in drug-adapted BRAFV600E melanoma cells

Anti-cancer drugs commonly target signal transduction proteins activated by mutation. In patients with BRAFV600E melanoma, small molecule RAF and MEK kinase inhibitors cause dramatic but often transient tumor regression. Emerging evidence suggests that cancer cells adapting by non-genetic mechanisms constitute a reservoir for the development of drug-resistant tumors. Here, we show that few hours after exposure to RAF/MEK inhibitors, BRAFV600E melanomas undergo adaptive changes involving disruption of negative feedback and sporadic pulsatile reactivation of the MAPK pathway, so that MAPK activity is transiently high enough in some cells to drive proliferation. Quantitative proteomics and computational modeling show that pulsatile MAPK reactivation is possible due to the co-existence in cells of two MAPK cascades: one driven by BRAFV600E that is drug-sensitive and a second driven by receptors that is drug-resistant. Paradoxically, this may account both for the frequent emergence of drug resistance and for the tolerability of RAF/MEK therapy in patients.

cancer biology↗

bioRxiv2019

Trading Genome Vulnerability for Stable Genetic Inheritance: Active Retrotransposons Help Maintain Pericentromeric Heterochromatin Required for Faithful Cell Division

Retrotransposons are extensively populated in vertebrate genomes, which, when active, are thought to cause genome instability with potential benefit to genome evolution. Retrotransposon-derived RNAs are also known to give rise to small endo-siRNAs to help maintain heterochromatin at their sites of transcription; however, as not all heterochromatic regions are equally active in transcription, it remains unclear how heterochromatin is maintained across the genome. Here, we attack these problems by defining the origins of repeat-derived RNAs and their specific chromatin registers in Drosophila S2 cells. We demonstrate that repeat RNAs are predominantly derived from active Gypsy elements, and upon their processing by Dicer-2, these endo-siRNAs act in cis and trans to help maintain pericentromeric heterochromatin. Remarkably, we show that synthetic repeat-derived siRNAs are sufficient to rescue Dicer-2 deficiency-induced defects in heterochromatin formation in interphase and chromosome segregation during mitosis, thus demonstrating that active retrotransposons are actually required for stable genetic inheritance.

genomics↗

bioRxiv2019

Combined inhibition of mTOR and PIKKs exploits replicative and checkpoint vulnerabilities to induce death of PI3K-activated triple-negative breast cancer cells

SUMMARY SUMMARY HIGHLIGHTS INTRODUCTION RESULTS DISCUSSION FUNDING AUTHOR CONTRIBUTIONS STAR METHODS Cell lines METHOD DETAILS Western blotting Evaluation of drug sensitivity Immunofluorescence microscopy Primary antibodies and dilutions Single-stranded DNA ssDNA and... Live cell microscopy Extraction of polar metabolites Metabolomics profiling by... Isobolograms and analysis of... Cell cycle model and... QUANTIFICATION AND STATISTICAL... Viable cell counts ...

cancer biology↗

bioRxiv2017

Thalamocortical and Intracortical Laminar Connectivity Determines Sleep Spindle Properties

Spindle oscillations are brief oscillatory activity during non-rapid eye movement (NREM) sleep. Spindle density and synchronization properties are different in MEG versus EEG recordings in humans and also vary with learning performance, suggesting spindle involvement in memory consolidation. Using computational models, we identified network mechanisms that may explain differences in spindle properties across cortical structures. First, we report that differences in spindle occurrence between MEG and EEG data may arise from the properties of the core vs. matrix thalamocortical systems. The matrix system, projecting superficially, has wider thalamocortical fanout compared to the core system, projecting to the middle layers, and requires the recruitment of a larger population of neurons to initiate a spindle. Our model demonstrates that this property is sufficient to explain lower spindle density and higher spatial synchrony of spindles in the superficial cortical layers, as observed in the EEG signal. In contrast, spindles in the core system occurred more frequently but less synchronously, as observed in the MEG recordings. Futhermore, consistent with human recordings, in the model, spindles occurred independently in the core system but matrix system spindles commonly co-occurred with core one. We found that the intracortical excitatory connections from layer III/IV to layer V promote spindle propagation from the core to the matrix system, leading to widespread spindle activity. Our study predicts that plasticity of the intra and inter cortical connectivity can potentially be a mechanism for increasing in spindle density as observed during learning.\n\nAuthor summaryThe density of sleep spindles has been shown to correlate with memory consolidation. Further, sleep spindles occur more often in human MEG than EEG. We developed thalamocortical network model that is capable of spontaneous generation of spindles across cortical layers and that captures the essential statistical features of spindles observed in experiments. We predict that differences in thalamo-cortical connectivity, known from anatomical studies, lead to the differences in the spindle properties between EEG and MEG as observed in human recordings. Further, we predict that the intracortical connectivity between cortical layers, a property influenced by sleep preceding learning, increases spindle density. Results from our study highlight the role of cortical and thalamic projections on the occurrence and properties of spindles.

neuroscience↗