Biology subjects

Chen, X.

Publications and source records attributed to Chen, X..

At least 559 records · Page 31Linked to original sources

bioRxiv2024

Identification of Intrinsic Features for Cortical Separability of Human and Mouse Neurons

This work introduces a novel framework for holistic comparative analysis of cortical regions in mouse and human brains at single-neuron resolution, with a primary focus on the morphological and molecular characteristics of neurons. To do so, we generated one of the largest dendritic reconstruction datasets of cortical neurons to date, comprising 2,363 human neurons and 16,011 mouse neurons from the frontal, parietal, and temporal lobes, followed by establishing a rigorous procedure to identify anatomically and functionally corresponding brain regions with minimal variability in brain mapping. Additionally, we leveraged single nucleus/cell transcriptomic data from independent groups to validate the molecular correspondence of the brain regions identified in this study. The significance of these anatomically, functionally, and molecularly corresponding mouse-human region pairs is highlighted by examining the intrinsic features of their respective cortical regions. Our findings reveal that human neuron branching patterns differ dramatically from those in mouse brains, particularly in terms of dendritic branching frequency and normalized dendritic branching intervals. This difference is pronounced in the frontal and temporal lobes, underscoring the distinct neuronal architectures between the two species. At the single-neuron level, we found that neurons from the human frontal and parietal lobes are six times more separable than those from the same regions in mouse brains. This heightened separability is also observed between the frontal and temporal lobes, as well as between the parietal and temporal lobes in humans. We thoroughly explored the entire morphological feature space, along with its characteristic subspaces, and consistently found this distinct separability. Remarkably, this neuronal separability can be partially recapitulated when examining the global functional states of these brain lobes--using newly acquired Electroencephalography (EEG) and Magnetoencephalography (MEG) signals as physiological measures--as well as their global metabolic states, molecular profiles, and cortical geometry. These findings suggest that our comparative analysis of single-neuron intrinsic features could serve as a valuable foundation for future comprehensive studies of cross-species brain structures and functions.

neuroscience↗

bioRxiv2024

Cross-expression analysis reveals patterns of coordinated gene expression in spatial transcriptomics

Spatial transcriptomics promises to transform our understanding of tissue biology by molecularly profiling individual cells in situ. A fundamental question they allow us to ask is how nearby cells orchestrate their gene expression. Rather than focus on how these cells (samples) communicate with each other, we reframe the problem to investigate how genes (features) coordinate their expression between neighboring cells. To study these phenomena - called cross-expression - we compare all genes to find pairs that coordinate their expression between adjacent cells, thereby avoiding curating gene lists or annotating cell types. Our end-to-end method recovers ligand-receptor pairs as cross-expressing genes and finds gene combinations that mark anatomical regions, complementing marker gene-based region annotation. Leveraging the overlapping genes across different panels, we use multiple atlas-scale adult mouse brain datasets (~25 million cells, 695 samples, 8 technologies) to create an integrated, meta-analytic cross-expression network, whose communities are enriched in spatial processes such as synaptic signaling and G protein coupled receptor activity. Highlighting cross-expressions biological utility, our network shows that genes Drd1 and Gpr6, which are individually implicated in Parkinsons disease (PD) and are being pursued as therapeutic targets, are cross-expressed within the striatum, hinting at their joint role in PD pathophysiology. We provide an efficient R package (https://github.com/gillislab/CrossExpression/) to computationally analyze and visually explore cross-expression patterns, which allow us to better understand how genes coordinate their expression in space to perform tissue-level functions.

bioinformatics↗

bioRxiv2024

Unveil the Molecular Interplay between Aminoglycosides and Pseudouridine in IRES Translation

Eukaryotic ribosomes are enriched with pseudouridine, particularly at the functional centers targeted by antibiotics. Here we investigated the roles of pseudouridine in aminoglycoside-mediated translation inhibition by comparing the structural and functional properties of the wild-type ribosomes and those lacking pseudouridine (cbf5-D95A). We showed that the cbf5-D95A ribosomes have decreased thermostability and high sensitivity to aminoglycosides. When presented with an internal ribosome entry site (IRES) RNA, elongation factor eEF2, GTP, sordarin, hygromycin B preferentially binds to the cbf5-D95A ribosomes during initiation by blocking eEF2 binding and stalls the ribosomes in a non-rotated conformation, further hindering translocation. Hygromycin B binds to the inter-subunit bridge B2a that is known to be sensitive to pseudouridine, revealing a functional link between pseudouridine and aminoglycoside inhibition. Our results suggest that pseudouridine enhances both thermostability and conformational fitness of the ribosomes, thereby influencing their susceptibility to aminoglycosides. HighlightsO_LILoss of pseudouridine increases cell sensitivity to aminoglycosides C_LIO_LIPseudouridine enhances ribosome thermostability C_LIO_LIHygromycin B competes with eEF2 for the non-rotated ribosome C_LIO_LIHygromycin B deforms the codon-anticodon duplex C_LI

biochemistry↗

bioRxiv2024

Modulating DNA Polα Enhances Cell Reprogramming Across Species

As a fundamental biological process, DNA replication ensures the accurate copying of genetic information. However, the impact of this process on cellular plasticity in multicellular organisms remains elusive. Here, we find that reducing the level or activity of a replication component, DNA Polymerase (Pol), facilitates cell reprogramming in diverse stem cell systems across species. In Drosophila male and female germline stem cell lineages, reducing Pol levels using heterozygotes significantly enhances fertility of both sexes, promoting reproductivity during aging without compromising their longevity. Consistently, in C. elegans the pola heterozygous hermaphrodites exhibit increased fertility without a reduction in lifespan, suggesting that this phenomenon is conserved. Moreover, in male germline and female intestinal stem cell lineages of Drosophila, pol heterozygotes exhibit increased resistance to tissue damage caused by genetic ablation or pathogen infection, leading to enhanced regeneration and improved survival during post-injury recovery, respectively. Additionally, fine tuning of an inhibitor to modulate Pol activity significantly enhances the efficiency of reprogramming human embryonic fibroblasts into induced pluripotent cells. Together, these findings unveil novel roles of a DNA replication component in regulating cellular reprogramming potential, and thus hold promise for promoting tissue health, facilitating post-injury rehabilitation, and enhancing healthspan.

developmental biology↗

bioRxiv2024

Melanocortin-4 receptor antagonist TCMCB07 alleviates chemotherapy-induced anorexia and weight loss

Cancer patients undergoing chemotherapy often experience anorexia and weight loss that significantly deteriorates overall health, reduces treatment tolerance and quality of life, and worsens oncologic outcomes. There are currently few effective therapeutic options to mitigate these side effects. The central melanocortin system, which plays a pivotal role in regulating appetite and energy homeostasis, presents a logical target for treating anorexia and weight loss. In this preclinical study, we evaluated the efficacy of TCMCB07, a synthetic antagonist of the melanocortin-4 receptor, in mitigating anorexia and weight loss in several rat models of chemotherapy: cisplatin, 5-fluorouracil, cyclophosphamide, vincristine, doxorubicin, and a combination of irinotecan and 5-fluorouracil. Our results indicate that peripheral administration of TCMCB07 improved appetite, stabilized body weight, preserved fat and heart mass, and slightly protected lean mass after multiple cycles of chemotherapy. Furthermore, combining TCMCB07 with a growth differentiation factor 15 antibody enhanced treatment effectiveness. Similar effects from TCMCB07 treatment were observed in a rat tumor model following combination chemotherapy. No significant adverse effects nor increased chemotherapy-related toxicities were observed with TCMCB07 treatment. These findings suggest that peripheral administration of TCMCB07 holds promise as a therapeutic approach for alleviating chemotherapy-induced anorexia and weight loss, potentially benefiting numerous patients undergoing chemotherapy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/613069v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@cbe32borg.highwire.dtl.DTLVardef@1af55e7org.highwire.dtl.DTLVardef@30deb1org.highwire.dtl.DTLVardef@6c39a3_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2024

Integrated Transcriptome and Metabolome Analyses Reveal the Mechanism Regulating Bulbil Initiation and Development in Cystopteris chinensis

Cystopteris chinensis is an endangered fern endemic to China, which only has a small wild population due to its poor reproductive ability. However, we recently found that it can produce bulbils on its pinnule to generate new plants but the molecular mechanism underlying this unique phenomenon remained unknown. In this study, we have identified four distinct stages in the initiation and development of bulbils based on morphological and anatomical observation. We performed transcriptome and metabolome analyses on the collected samples at each stage. Through KEGG enrichment analysis, it was found that the phytohormone signal transduction, starch and sucrose metabolism, phenylpropanoid biosynthesis, and flavonoid biosynthesis pathways play a significant role in regulating bulbil initiation and development. Specifically, the involvement of three phytohormones and sugar substances was identified in the process of bulbil initiation. Our study provides the first detailed observation of the bulbils in C. chinensis and explains their initiation and development at the molecular level. However, more in-depth studies are needed to discover the functions of key genes controlling the formation of bulbils to conserve the endangered C. chinensis population.

plant biology↗

bioRxiv2024

YAP/TAZ signaling in allantois-derived cells is required for placental vascularization

Normal placental development and angiogenesis are crucial for fetal growth and maternal health during pregnancy. However, molecular regulation of placental angiogenesis has been difficult to study due to a lack of specific genetic tools that isolate the placenta from the embryo and yolk sac. To address this gap in knowledge we recently developed Hoxa13Cre mice in which Cre is expressed in allantois-derived cells, including placental endothelial and stromal cells. Mice lacking the transcriptional regulators Yes-associated protein (YAP) and PDZ-binding motif (TAZ) in allantois-derived cells exhibit embryonic lethality at midgestation with compromised placental vasculature. snRNA-seq analysis revealed transcriptional changes in placental stromal cells and endothelial cells. YAP/TAZ mutants exhibited significantly reduced placental stromal cells prior to the endothelial architectural change, highlighting the role of these cells in placental vascular growth. These results reveal a central role for YAP/TAZ signaling during placental vascular growth and implicate Hoxa13-derived placental stromal cells as a critical component of placental vascularization.

developmental biology↗

bioRxiv2024

Linker histone regulates the myeloid versus lymphoid bifurcation of multipotent hematopoietic stem and progenitors

Myeloid-biased differentiation of multipotent hematopoietic stem and progenitor cells (HSPCs) occurs with aging or exhaustion. The molecular mechanism(s) responsible for this fate bias remain unclear. Here we report that linker histone regulates HSPC fate choice at the lymphoid versus myeloid bifurcation. HSPCs expressing H1.0 from a doxycycline (dox) inducible transgene favor the lymphoid fate, display strengthened nucleosome organization and reduced chromatin accessibility at genomic regions hosting key myeloid fate drivers. The transcription factor Hlf is located in one of such regions, where chromatin accessibility and gene expression is reduced in H1.0high HSPCs. Furthermore, H1.0 protein in HSPCs decreases in an aspartyl protease dependent manner, a process enhanced in response to interferon alpha (IFN) signaling. Aspartyl protease inhibitors preserve endogenous H1.0 levels and promote the lymphoid fate of wild type HSPCs. Thus, our work uncovers a point of intervention to mitigate myeloid skewed hematopoiesis.

developmental biology↗

bioRxiv2024

A benchmarking study of copy number variation inference methods using single-cell RNA-sequencing data

Single-cell RNA-sequencing (scRNA-seq) has emerged as a powerful tool for cancer research, enabling in-depth characterization of tumor heterogeneity at the single-cell level. Recently, scRNA-seq copy number variation (scCNV) inference methods have been developed, expanding the application of scRNA-seq to study genetic heterogeneity in cancer using transcriptomic data. However, the fidelity of these methods has not been investigated systematically. In this study, we benchmarked five commonly used scCNV inference methods, HoneyBADGER, CopyKAT, CaSpER, inferCNV, and sciCNV. We evaluated their performance across four different scRNA-seq platforms derived data from a multicenter study. We further evaluated the scCNV performance using scRNA-seq datasets derived from mixed samples consisting of five human lung adenocarcinoma cell lines and generated a clinical scRNA-seq dataset from a human small cell lung cancer patient to validate our findings. Our evaluation criteria included sensitivity and specificity of CNV detection, and subclone identification from mixed cancer samples. We found that the sensitivity and specificity of the five scCNV inference methods varied, depending on the selection of reference data, sequencing depths, and read lengths. Overall, CopyKAT and CaSpER exhibited superior performance to other methods, while inferCNV, sciCNV, and CopyKAT outperformed other methods in subclone identification accuracy. Remarkably, inferCNV achieved high accuracy in subclone identification when using data from a "single scRNA-seq protocol", however, when applying these methods to a dataset derived from multiple scRNA-seq platforms from the mixed samples, we found that batch effects significantly affected the performance of subclone identification for most methods, except for HoneyBADGER. Our benchmarking study revealed the strengths and weaknesses of each of the five scCNV inference methods and provided guidance for selecting the optimal CNV inference method using scRNA-seq data.

bioinformatics↗

bioRxiv2024

The neurotrophin artemin and its receptor GFRα3 mediate migraine-like pain via the ion channel TRPM8

BackgroundMigraine has a strong genetic foundation, including both monogenic and polygenic types. The former are rare, with most migraine considered polygenic, supported by genome-wide association studies (GWAS) identifying numerous genetic variants associated with migraine risk. Surprisingly, some of the most common mutations are associated with TRPM8, a non-selective cation channel that is the primary sensor of cold temperatures in primary afferent neurons of the somatosensory system. However, it is unlikely that the temperature sensitivity of TRPM8 underlies its role in migraine pathogenesis. To define the basis of the channels involvement, we reasoned that cellular processes that increase cold sensitivity in the skin, such as the neurotrophic factor artemin, via its receptor GFR3, also mediate TRPM8-associated migraine-like pain in the meninges. MethodsTo investigate the role of artemin and GFR3 in preclinical rodent migraine models, we infused nitroglycerin acutely and chronically, and measured changes in periorbital and hind paw mechanical sensitivity in male and female mice lacking GFR3, after neutralization of free artemin with specific monoclonal antibodies, or by systemic treatment with a TRPM8-specific antagonist. Further, in wildtypes and mice lacking either GFR3 or TRPM8, we tested the effects of supradural infusions of a mix of inflammatory mediators, artemin, and a TRPM8-specific agonist on migraine-related pain in mice. ResultsWe find that mechanical allodynia induced by systemic nitroglycerin, or supradural infusion of inflammatory mediators, involves GFR3. In addition, neutralization of circulating artemin reduces the nitroglycerin phenotype, demonstrating the importance of this neurotrophic pathway. Further, we show TRPM8 expression in the meninges and that direct supradural infusion of either a TRPM8-specific agonist or artemin itself produces mechanical allodynia, the latter dependent on TRPM8 and ameliorated by concurrent treatment with sumatriptan. ConclusionsThese results indicate that neuroinflammatory events in the meninges can produce migraine-like pain in mice via artemin and GFR3, likely acting upstream of TRPM8, providing a novel pathway that may contribute to migraine pathogenesis.

neuroscience↗

bioRxiv2024

Epigenomic, transcriptomic and proteomic characterizations of reference samples

A variety of newly developed next-generation sequencing technologies are making their way rapidly into the research and clinical applications, for which accuracy and cross-lab reproducibility are critical, and reference standards are much needed. Our previous multicenter studies under the SEQC-2 umbrella using a breast cancer cell line with paired B-cell line have produced a large amount of different genomic data including whole genome sequencing (Illumina, PacBio, Nanopore), HiC, and scRNA-seq with detailed analyses on somatic mutations, single-nucleotide variations (SNVs), and structural variations (SVs). However, there is still a lack of well-characterized reference materials which include epigenomic and proteomic data. Here we further performed ATAC-seq, Methyl-seq, RNA-seq, and proteomic analyses and provided a comprehensive catalog of the epigenomic landscape, which overlapped with the transcriptomes and proteomes for the two cell lines. We identified >7,700 peptide isoforms, where the majority (95%) of the genes had a single peptide isoform. Protein expression of the transcripts overlapping CGIs were much higher than the protein expression of the non-CGI transcripts in both cell lines. We further demonstrated the evidence that certain SNVs were incorporated into mutated peptides. We observed that open chromatin regions had low methylation which were largely regulated by CG density, where CG-rich regions had more accessible chromatin, low methylation, and higher gene and protein expression. The CG-poor regions had higher repressive epigenetic regulations (higher DNA methylation) and less open chromatin, resulting in a cell line specific methylation and gene expression patterns. Our studies provide well-defined reference materials consisting of two cell lines with genomic, epigenomic, transcriptomic, scRNA-seq and proteomic characterizations which can serve as standards for validating and benchmarking not only on various omics assays, but also on bioinformatics methods. It will be a valuable resource for both research and clinical communities.

genomics↗

bioRxiv2024

Structural mimicry of UM171 and neomorphic cancer mutants co-opts E3 ligase KBTBD4 for HDAC1/2 recruitment

Neomorphic mutations and drugs can elicit unanticipated effects that hinder mechanistic understanding for clinical practice. Recurrent indel mutations in the Kelch domain of the KBTBD4 E3 ligase rewire epigenetic programs for stemness in medulloblastoma by recruiting LSD1-CoREST-HDAC1/2 complexes as neo-substrates for ubiquitination and degradation. Remarkably, UM171, an investigational drug for haematopoietic stem cell transplantation, was found to degrade LSD1-CoREST-HDAC1/2 complexes in a wild-type KBTBD4-dependent manner, suggesting a potential common mode of action. We identified that these neomorphic interactions were mediated by the HDAC deacetylase domain. Cryo-EM studies of both wild-type and mutant KBTBD4 captured 2:1 and 2:2 KBTBD4-HDAC2 complexes at resolutions spanning 2.7 [A] to 3.1 [A]. The mutant and drug-induced complexes adopted similar structural assemblies requiring both Kelch domains in the KBTBD4 dimer for each HDAC2 interaction. UM171 was identified as a bona fide molecular glue binding across the ternary interface. Most strikingly, the indel mutation reshaped the same surface of KBTBD4 providing the first example of a natural mimic of a molecular glue. Together, the structures provide mechanistic understanding of neomorphic KBTBD4 and help to explain the structure-activity relationships of UM171 derivatives for future drug design.

molecular biology↗

bioRxiv2024

Nutrient starvation activates ECM remodeling gene enhancers associated with inflammatory bowel disease risk in fibroblasts

Nutrient deprivation induces a reversible cell cycle arrest state termed quiescence, which often accompanies transcriptional silencing and chromatin compaction. Paradoxically, nutrient deprivation is associated with activated fibroblast states in pathological microenvironments in which fibroblasts drive extracellular matrix (ECM) remodeling to alter tissue environments. The relationship between nutrient deprivation and fibroblast activation remains unclear. Here, we report that serum deprivation extensively activates transcription of ECM remodeling genes in cultured fibroblasts, despite the induction of quiescence. Starvation-induced transcriptional activation accompanied large-scale histone acetylation of putative distal enhancers, but not promoters. The starvation-activated putative enhancers were enriched for non-coding genetic risk variants associated with inflammatory bowel disease (IBD), suggesting that the starvation-activated gene regulatory network may contribute to fibroblast activation in IBD. Indeed, the starvation-activated gene PLAU, encoding uPA serine protease for plasminogen and ECM, was upregulated in inflammatory fibroblasts in the intestines of IBD patients. Furthermore, the starvation-activated putative enhancer at PLAU, which harbors an IBD risk variant, gained chromatin accessibility in IBD patient fibroblasts. This study implicates nutrient deprivation in transcriptional activation of ECM remodeling genes in fibroblasts and suggests nutrient deprivation as a potential mechanism for pathological fibroblast activation in IBD. HIGHLIGHTS- Serum starvation transcriptionally activates ECM remodeling genes in fibroblasts. - Fibroblast starvation activates putative distal enhancers associated with ECM remodeling genes. - Starvation-activated putative enhancers are enriched for inflammatory bowel disease (IBD) risk variants. - PLAU enhancer and expression are activated in IBD intestinal fibroblasts, as in starved fibroblasts.

genomics↗

bioRxiv2024

PSMA-specific CAR-engineered macrophages for therapy of prostate cancer

Chimeric antigen receptor (CAR)-modified macrophages (CAR-Ms) are a promising approach for the treatment of solid tumors due to its high infiltration and immune-regulation activity. Prostate cancer is a typical solid tumor associated with highly immunosuppressive microenvironment. To date, the potential application of CAR-M cell therapy in prostate cancer has been infrequently explored. The prostate-specific membrane antigen (PSMA) functions as a specific biomarker for prostate cancer. In this study, we assessed the antitumor efficacy of PSMA-targeted CAR-Ms in preclinical models. CAR-Ms were engineered to express a PSMA-specific single-chain variable fragment (scFv) and co-stimulatory domains. In vitro data demonstrated specific cytotoxicity of CAR-Ms against PSMA-expressing prostate cancer cells, which was further supported by transcriptome analysis demonstrating the pro-inflammatory phenotypes of CAR-Ms. In vivo studies using xenograft mouse models confirmed significant tumor regression after administration of PSMA-targeted CAR-Ms compared to controls. Histopathological analysis showed infiltration of CAR-Ms into tumor tissues without off-target toxicity. These results highlight the strong antitumor activity and safety of PSMA-targeted CAR-Ms, supporting their potential as a new immunotherapy for prostate cancer.

bioengineering↗

bioRxiv2024

Discovery of novel quinoline papain-like protease inhibitors for COVID-19 through topology constrained molecular generative model

The rapid emergence of drug-resistant SARS-CoV-2 variants poses a persistent challenge to current antiviral strategies. Mutations in key viral targets, including RNA-dependent RNA polymerase (RdRp), main protease (3CLpro), and papain-like protease (PLpro), have been shown to markedly reduce the efficacy of approved therapeutics, highlighting the urgent need for next-generation antivirals capable of overcoming resistance. Here, we report the discovery of a novel class of PLpro inhibitors through an AIDD strategy based on a topology-constrained molecular generative model (Tree-Invent) integrated with structure-guided optimization. Scaffold hopping from a previously reported lead enabled the identification of a quinoline-based chemical series with substantially improved metabolic stability and antiviral potency. Structure-guided optimization yielded compound GZNL-2016, which exhibited potent enzymatic inhibition of PLpro (IC50 = 10.5 nM), robust antiviral activity against multiple SARS-CoV-2 variants, including Omicron BA.5 and XBB.1, and favorable pharmacokinetic properties following oral administration. Notably, GZNL-2016 retained substantial inhibitory activity against the clinically relevant drug-resistant mutant PLpro E167K (IC50 = 480.2 nM; Ki = 439.3 nM), in contrast to previously reported inhibitors that exhibit markedly reduced potency. In a SARS-CoV-2 infection mouse model, oral administration of GZNL-2016 significantly reduced pulmonary viral titers, demonstrating in vivo antiviral efficacy. Collectively, this study establishes an AI-enabled strategy for rapid antiviral discovery and identifies GZNL-2016 as a promising lead compound to address the threat of coronavirus infections caused by drug-resistant mutant SARS-CoV-2 variants. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/611841v3_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@ecbd3eorg.highwire.dtl.DTLVardef@7c663corg.highwire.dtl.DTLVardef@11c0e37org.highwire.dtl.DTLVardef@e950f0_HPS_FORMAT_FIGEXP M_FIG C_FIG We leveraged an AI generative model to discover a novel PLpro inhibitor with excellent liver stability, low CYP, hERG inhibition and reasonable oral PK properties. At the same time, the compound 16 exhibits high efficacy for the resistance mutation E167K, which resulted in severe resistance to the previously reported inhibitor Jun12682 and PF-07957472.

microbiology↗

bioRxiv2024

Endophilin A1 facilitates organization of the GABAergic postsynaptic machinery to maintain excitation-inhibition balance

The assembly and operation of neural circuits in the brain rely on the coordination and balance of excitatory and inhibitory activities. Inhibitory synapses are key regulators of the functional balance of neural circuits. However, due to the diversity of inhibitory presynaptic neurons, the complex composition of postsynaptic receptor subunits and the lack of typical postsynaptic dense structure, there are relatively few studies on the regulatory mechanisms for inhibitory synaptic structure and function, and insufficient understanding of the cellular and molecular abnormalities of inhibitory synapses in neurological and neuropsychiatric disorders. Here, we report a crucial role for endophilin A1 in inhibitory synapses. We show that endophilin A1 directly interacts with the inhibitory postsynaptic scaffold protein gephyrin in excitatory neurons, and promotes organization of the inhibitory postsynaptic density and synaptic recruitment/stabilization of the {gamma}-aminobutyric acid type A receptors via its plasma membrane association and actin polymerization promoting activities. Loss of endophilin A1 by gene knockout in mouse hippocampal CA1 pyramidal cells weakens inhibitory synaptic transmission and causes imbalance in the excitatory/inhibitory function of neural circuits, leading to increased susceptibility to epilepsy. Our findings identify endophilin A1 as an iPSD component and provide new insights into the organization and stabilization of inhibitory postsynapses to maintain E/I balance as well as the pathogenesis of epilepsy.

neuroscience↗

bioRxiv2024

PIEZO-dependent mechano-sensing of the niche is essential for intestinal stem cell fate decision and maintenance

Stem cells continuously perceive and respond to various environmental signals to maintain homeostasis. In addition to biochemical factors, the stem cell niche is subjected to mechanical and physical cues. However, it remains unclear how stem cells can sense mechanical signals from their niche in vivo. Since intestinal stem cells constantly and directly face the external environment, we investigated the roles of mechano-sensing PIEZO ion channels in the gut stem cell niche. By employing mouse genetics and performing single-cell RNAseq analysis, we revealed the absolute requirement for PIEZO channels in intestinal stem cell (ISC) state dynamics and maintenance. In vivo measurement of basement membrane region stiffness demonstrated that ISCs reside in a more rigid microenvironment at the bottom of the crypt. Using 3D and 2D organoid systems combined with bioengineered substrates and a cell stretching device, we found that PIEZO channels are activated by high extracellular matrix stiffness and tissue tension to modulate ISC behavior. This study delineates the mechanistic cascade of PIEZO channel activation in ISCs from the upstream extracellular stimuli through the downstream signaling activation that coordinates stem cell fate decision and maintenance.

cell biology↗

bioRxiv2024

Endogenous retroviruses activate MARCO-mediated inflammatory response to block retroviral infection

Endogenous retroviruses (ERVs) are remnants of ancient retroviral infections and can profoundly affect the host antiviral innate immune response, although the mechanisms by which these changes occur are largely unknown. Here we report that chicken-specific ERVs exert genetic resistance to exogenous retrovirus infection. Mechanistically, chicken-specific ERVs activated the scavenger receptor MARCO (macrophage receptor with collagenous structure)-mediated TLR3-IL-1{beta} inflammatory response in macrophages. Under the presence of MARCO, macrophages response to viral infection through inducing TLR3-IL-1{beta} inflammatory response. Conversely, lack of MARCO increased the viral replication levels and attenuated the antiviral inflammatory response. MARCO-mediated ligand delivery enhances TLR3-IL-1{beta} antiviral response, and IL-1{beta} expression is responsible for viral inhibition. Restoring MARCO or IL-1{beta} expression overcomes viral infection in macrophages. Our study provides new insights into the molecular mechanisms underlying the host defense against exogenous retroviruses infection and may have important implications for the development of novel therapeutic strategies against retroviruses infection.

immunology↗