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Wang, J.

Publications and source records attributed to Wang, J..

At least 955 records · Page 53Linked to original sources

A unified framework for drug-target interaction prediction by semantic-guided meta-path method

Drug-target interaction (DTI) prediction plays a crucial role in drug development, impacting areas such as virtual screening, drug repurposing, and the identification of potential drug side effects. Despite significant efforts dedicated to improving DTI prediction, existing methods still struggle with the challenges posed by the high sparsity of DTI datasets and the complexity of capturing heterogeneous information in biological networks. To address these challenges, we propose a unified framework for DTI prediction based on a semantics-guided meta-path walk. Specifically, we first pre-train drug and protein embeddings to capture their semantic information. This semantic information is then leveraged to guide a meta-path-based random walk on the biological heterogeneous network, generating sequences of interactions. These sequences are used to compute embedding features via a heterogeneous skip-gram model, which are subsequently fed into downstream tasks to predict DTIs. SGMDTI achieves substantial performance improvement over other state-of-the-art methods for drug-target interaction prediction. Moreover, it excels in the cold-start scenario, which is often a challenging case in DTI prediction. These results indicate the effectiveness of our approach in predicting drug-target interactions.Experimental datasets and experimental codes can be found in https://github.com/HYLPRC/SGMDTI

bioinformatics↗

Coma pattern-based autofocusing unlocks superior performance in unravelling single-cell dynamics during bacterial cold shock response

Imaging-based single-cell physiological profiling holds great potential for uncovering fundamental bacterial cold shock response (CSR) mechanisms, but its application is impeded by severe focus drift during rapid temperature downshifts required for CSR induction. Here, we introduce LUNA (Locking Under Nanoscale Accuracy), an innovative autofocusing method that leverages the coma pattern of detection light to characterize focus drift. LUNA improves the focusing precision down to 3 nm and extends the focusing range to at least 40 times the objective depth-of-focus. These advancements enable us to investigate the complete dynamics of bacterial single-cell CSR, revealing continuous cellular growth and division. We resolve a three-phase adaptation process characterized by distinct growth deceleration dynamics, and show that bacterial cells maintain robust size regulation and coordinate uniform adaptation to cold shock through synchronized growth and elapsed cycles. Notably, a model based on scattering theory reconciles the paradox between the growth lag of batch culture and continuous single-cell growth. These findings fundamentally transform our understanding of bacterial CSR and highlight LUNAs excellent potential for expanding state-of-the-art research in biology.

microbiology↗

Chromatin interaction maps of human arterioles reveal new mechanisms for the genetic regulation of blood pressure

Arterioles are small blood vessels located just upstream of capillaries in nearly all tissues. The constriction and dilation of arterioles regulate tissue perfusion and are primary determinants of systemic blood pressure (BP). Abnormalities in arterioles are central to the development of major diseases such as hypertension, stroke, and microvascular complications of diabetes. Despite the broad and essential role of arterioles in physiology and disease, current knowledge of the functional genomics of arterioles is largely absent, partly because it is challenging to obtain and analyze human arteriole samples. Here, we report extensive maps of chromatin interactions, single-cell expression, and other molecular features in human arterioles and uncover new mechanisms linking human genetic variants to gene expression in vascular cells and the development of hypertension. Compared to large arteries, arterioles exhibited a higher proportion of pericytes which were strongly associated with BP traits. BP-associated single nucleotide polymorphisms (SNPs) were enriched in chromatin interaction regions in arterioles, particularly through enhancer SNP-promoter interactions, which were further linked to gene expression specificity across tissue components and cell types. Using genomic editing in animal models and human induced pluripotent stem cells, we discovered novel mechanisms linking BP-associated noncoding SNP rs1882961 to gene expression through long-range chromatin contacts and revealed remarkable effects of a 4-bp noncoding genomic segment on hypertension in vivo. We anticipate that our rich data and findings will advance the study of the numerous diseases involving arterioles. Moreover, our approach of integrating chromatin interaction mapping in trait-relevant tissues with SNP analysis and in vivo and in vitro genome editing can be applied broadly to bridge the critical gap between genetic discoveries and physiological understanding.

genomics↗

Multi-modal profiling identifies CD4+CXCR5+PD-1- Tfh cells as prognostic and predictive biomarkers for response to R-CHOP therapy in human DLBCL

Despite the improvements in clinical outcomes for patients with Diffuse Large B-Cell Lymphoma (DLBCL), a significant proportion of those patients still face challenges with refractory/relapsed (R/R) disease after receiving first-line R-CHOP treatment. Characterizing the heterogeneity of the tumor microenvironment (TME) in diffuse large B cell lymphoma (DLBCL) is crucial for understanding relapsed/refractory disease. However, the complex and diverse nature of the TME has impeded progress. Here, using single-cell RNA sequencing(scRNA-seq), we explored the DLBCL landscape at single-cell resolution, profiling 77,344 cells from both primary and relapsed DLBCL patients. We further investigated the shared and distinct molecular and cellular features of tumor microenvironment in both primary and relapsed DLBCL tumors by integrating next-generation DNA sequencing data and multiple scRNA-seq datasets from total 72,351 cells. Our results demonstrated that there was a significant decrease of CD4+CXCR5+PD-1- Tfh cells, along with excessive activation of the TNF-NF{kappa}B signaling pathways in malignant B cells in R/R disease. Furthermore, by using multiplex IHC, we confirmed that CD4+CXCR5+PD-1- Tfh cells are prognostic and predictive biomarkers for response to R-CHOP treatment. As a proof of concept, we successfully generated mutilplexed images of CD4+CXCR5+PD-1- Tfh cells from a single DAPI staining in human DLBCL tissues through using generative artificial intelligence. Our study offers critical insights into the heterogeneity and molecular features of DLBCL, shedding light on the crucial role of CD4+CXCR5+PD-1- Tfh cells in the recurrent process. HighlightsO_LIShared and distinct molecular and cellular features of tumor microenvironment in both primary and relapsed DLBCL tumors; C_LIO_LIThe characteristic of relapsed DLBCL TME is a dysfunctional immune microenvironment with a significant decrease of CD4+CXCR5+PD-1- Tfh cells. C_LIO_LICD4+CXCR5+PD-1- Tfh cells are prognostic and predictive biomarkers for response to R-CHOP treatment C_LIO_LIDetermination of CD4+CXCR5+PD-1- Tfh cells in human DLBCL tissues through using generative artificial intelligence. C_LI

immunology↗

Large Serine Integrase Off-Target Discovery with Deep Learning for Genome Wide Prediction

Large Serine Integrases (LSIs) hold significant therapeutic promise due to their ability to efficiently incorporate gene-sized DNA into the human genome, offering a method to integrate healthy genes in patients with monogenic disorders or to insert gene circuits for the development of advanced cell therapies. To advance the application of LSIs for human therapeutic applications, new technologies and analytical methods for predicting and characterizing off-target recombination by LSIs are required. It is not experimentally tractable to validate off-target editing at all potential off-target sites in therapeutically relevant cell types because of sample limitations and genetic variation in the human population. To address this gap, we constructed a deep learning model named IntQuery that can predict LSI activity genome-wide. For Bxb1 integrase, IntQuery was trained on quantitative off-target data from 410,776 cryptic attB sequences discovered by Cryptic-seq, an unbiased in vitro discovery technology for LSI off-target recombination. We show that IntQuery can accurately predict in vitro LSI activity, providing a tool for in silico off-target prediction of large serine integrases to advance therapeutic applications.

bioinformatics↗

Curative levels of endogenous gene replacement achieved in non-human primate liver using programmable genomic integration

The ability to efficiently place a large piece of DNA in a specific genomic location has been a goal for the gene therapy field since its inception; however, despite significant advances in gene editing technology, this had yet to be achieved. Here we describe two methods of programmable genomic integration (PGI) that overcome some of the limitations of current approaches. Using a combination of clinically validated delivery technologies (LNP, AAV), we demonstrate the ability to specifically integrate large (>2 kb) DNA sequences into endogenous introns in the liver of non-human primates (NHP). PGI was effective across multiple genomic locations and transgenes, and insertion led to expression from the endogenous promoter. PGI was highly efficient, achieving expression in >50% of liver cells after a single course of treatment, which would be curative for most monogenic recessive liver diseases. This is the first report of clinically curative level of gene insertion at endogenous loci in NHP.

bioengineering↗

Leveraging Transfer Learning for Predicting Protein-Small Molecule Interactions

A complex web of intermolecular interactions defines and regulates biological processes. Understanding this web has been particularly challenging because of the sheer number of actors in biological systems: [~]104 proteins in a typical human cell offer a plausible 108 interactions. This number grows rapidly if we consider metabolites, drugs, nutrients, and other biological molecules. The relative strength of interactions also critically affects these biological processes. However, the small and often incomplete datasets (103-104 protein-ligand interactions) traditionally used for binding affinity predictions limit the ability to capture the full complexity of these interactions. To overcome this challenge, we developed Yuel 2, a novel neural network-based approach that leverages transfer learning to address the limitations of small datasets. Yuel 2 is pre-trained on a large-scale dataset to learn intricate structural features and then fine-tuned on specialized datasets like PDBbind to enhance the predictive accuracy and robustness. We show that Yuel 2 predicts multiple binding affinity metrics - Kd, Ki, and IC50 - between proteins and small molecules, offering a comprehensive representation of molecular interactions crucial for drug design and development.

bioinformatics↗

Dnajc3 (HSP40) Modulates Axon Regeneration in the Mouse Optic Nerve

A forward genetics approach was used to identify genomic elements enhancing axon regeneration in the BXD recombinant mouse strains. Axon regeneration was induced by knocking down Pten in retinal ganglion cells (RGCs) using adeno-associated virus (AAV) to deliver an shRNA followed by an intravitreal injection of Zymosan with CPT-cAMP that produced a mild inflammatory response. RGC axons were damaged by optic nerve crush (ONC). Following a 12-day survival period, regenerating axons were labeled by intravitreal injection of Cholera Toxin B (CTB) conjugated with Alexa Fluor 647. Two days later, labeled axons within the optic nerve were examined to determine the number of regenerating axons and the distance they traveled down the optic nerve. The analysis revealed a surprising difference in the amount of axonal regeneration across all 33 BXD strains. There was a 7.5-fold difference in the number of regenerating axons and a 4-fold difference in distance traveled by regenerating axons. These data were used to generate an integral map defining genomic loci modulating the enhanced axonal regeneration. A quantitative trait locus modulating axon regeneration was identified on Chromosome 14 (115 to 119 Mb). Within this locus were 16 annotated genes. Subsequent testing revealed that one candidate gene, Dnajc3, modulates axonal regeneration. Dnajc3 encodes Heat Shock Protein 40 (HSP40), which is a molecular chaperone. Knocking down Dnajc3 in the high regenerative strain (BXD90) led to a decreased regeneration response, while overexpression of Dnajc3 in a low regenerative strain (BXD34) resulted in an increased regeneration response. These findings suggest that Dnajc3 not only increases the number of regenerating axons, it also increases the distance those axons travel. This may prove to be critical for functional recovery in large mammals, where the distance axons travel to their target is considerably longer than that of the mouse. Thus, Dnajc3 may play a critical role for functional recovery in humans by increasing the number of regenerating axons and the distance the regenerating axons travel.

neuroscience↗

Intranasal hemagglutinin protein boosters induce robust mucosal immunity and cross-protection against influenza A viral challenge

Licensed parenteral influenza vaccines induce systemic antibody responses and alleviate disease severity but do not efficiently prevent viral entry and transmission due to the lack of local mucosal immune responses. Here, we describe intranasal booster strategy with unadjuvanted recombinant hemagglutinin (HA) following initial mRNA-LNP vaccination, Prime and HA. This regimen establishes highly protective HA-specific mucosal immune memory responses in the respiratory tract. Intranasal HA boosters provided significantly reduced viral replication compared to parenteral mRNA-LNP boosters in both young and old mice. Correlation analysis revealed that slightly increased levels of nasal IgA are significantly associated with a reduced viral burden in the upper respiratory tract. Intranasal boosting with an antigenically distinct H1 HA conferred sterilizing immunity against heterologous H1N1 virus challenge. Additionally, a heterosubtypic intranasal H5 HA booster elicited cross-reactive mucosal humoral responses. Our work illustrates the potential of a nasal HA protein booster as a needle- and adjuvant-free strategy to prevent infection and disease from influenza A viruses. One Sentence SummaryAdjuvant-free nasal booster induces protective immunity against influenza infection.

immunology↗

Multimodal integration of single cell ATAC-seq data enables highly accurate delineation of clinically relevant tumor cell subpopulations

Accurately deciphering tumor cellular heterogeneity is crucial for developing effective treatments. While single-cell epigenomics assays offer powerful insights into studying tumor heterogeneity beyond the transcriptional level, their application remains a significant challenge. To address this, we introduce Multimodal-based Analysis of scATAC-Seq data (MAAS), a method designed to identify functional tumor cell subpopulations and reconstruct their lineages from single-cell sequencing assay for transposase-accessible chromatin (scATAC-seq). MAAS uniquely integrates multimodal information, encompassing chromatin accessibility, copy number variations (CNVs), and single-nucleotide variants, through self-expressive multimodal matrix factorization. MAAS outperforms existing methods in accuracy and robustness on both simulated and real datasets. When applied to multiple glioma scATAC-seq datasets, MAAS uncovered a previously hidden tumor cell subpopulation resistant to temozolomide treatment. Furthermore, MAAS effectively detected clinically relevant subpopulations with low CNVs, such as those found in pediatric ependymoma and B-cell lymphoma. Additionally, we developed a novel MAAS-derived clinical signature that provides superior prognostic prediction than traditional clinicopathologic features across multiple cancer types. In summary, MAAS significantly advances the identification of clinically relevant tumor cell subpopulations, thereby accelerating the discovery of potential therapeutic targets.

bioinformatics↗

Longitudinal multi-omics reveals pathogenic TSC2 variants disrupt developmental trajectories of human cortical organoids derived from Tuberous Sclerosis Complex

Tuberous Sclerosis Complex (TSC), an autosomal dominant condition, is caused by heterozygous mutations in either the TSC1 or TSC2 genes, manifesting in systemic growth of benign tumors. In addition to brain lesions, neurologic sequelae represent the greatest morbidity in TSC patients. Investigations utilizing TSC1/2-knockout animal or human stem cell models suggest that TSC deficiency-causing hyper-activation of mTOR signaling might precipitate anomalous neurodevelopmental processes. However, how the pathogenic variants of TSC1/2 genes affect the longitudinal trajectory of human brain development remains largely unexplored. Here, we employed 3-dimensional cortical organoids derived from induced pluripotent stem cells (iPSCs) from TSC patients harboring TSC2 variants, alongside organoids from age- and sex-matched healthy individuals as controls. Through comprehensively longitudinal molecular and cellular analyses of TSC organoids, we found that TSC2 pathogenic variants dysregulate neurogenesis, synaptogenesis, and gliogenesis, particularly for reactive astrogliosis. The altered developmental trajectory of TSC organoids significantly resembles the molecular signatures of neuropsychiatric disorders, including autism spectrum disorders, epilepsy, and intellectual disability. Intriguingly, single cell transcriptomic analyses on TSC organoids revealed that TSC2 pathogenic variants disrupt the neuron/reactive astrocyte crosstalk within the NLGN-NRXN signaling network. Furthermore, cellular and electrophysiological assessments of TSC cortical organoids, along with proteomic analyses of synaptosomes, demonstrated that the TSC2 variants precipitate perturbations in synaptic transmission, neuronal network activity, mitochondrial translational integrity, and neurofilament formation. Notably, similar perturbations were observed in surgically resected cortical specimens from TSC patients. Collectively, our study illustrates that disease-associated TSC2 variants disrupt the neurodevelopmental trajectories through perturbations of gene regulatory networks during early cortical development, leading to mitochondrial dysfunction, aberrant neurofilament formation, impaired synaptic formation and neuronal network activity.

neuroscience↗

Efficacy and Safety of a novel virulent phage against acute pulmonary infection of Acinetobacter baumanniii in mice

Acinetobacter baumannii (A.baumannii) is a notable opportunistic pathogen responsible for severe hospital-acquired infections, with multidrug-resistant strains posing significant treatment challenges. Phage therapy, which employs bacteriophages as natural bacterial antagonists, has gained renewed attention as a promising solution to combat antibiotic-resistant infections. In this study, we isolated and characterized a novel virulent phage, vB_AbaS_qsb1, which specifically lyses A.baumannii. Phylogenetic and genomic analyses indicate that vB_AbaS_qsb1 is the founding member of a previously unreported genus, which we have named as Acinibactriovirus, with Acinibactriovirus lysinus as the type species. vB_AbaS_qsb1 demonstrated robust stability across diverse temperature and pH ranges, a short latent period, and no known virulence or antibiotic resistance genes within its 54,713 bp dsDNA genome. Safety assessments showed that high-dose vB_AbaS_qsb1 induced no adverse effects in mice, with histopathology confirming its safety profile. Therapeutic experiments further indicated that vB_AbaS_qsb1 provided at least 50% protection against A.baumannii-induced pneumonia, significantly reducing bacterial loads and inflammation markers, while maintaining high phage titers in lung tissue.This study introduces vB_AbaS_qsb1 as a promising candidate for phage therapy against A.baumannii, offering both innovative insights and a valuable framework for future isolation, genomic characterization, and efficacy evaluation of phages targeting antibiotic-resistant bacteria. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/617119v3_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@17bf4cdorg.highwire.dtl.DTLVardef@104c49eorg.highwire.dtl.DTLVardef@89e1dorg.highwire.dtl.DTLVardef@1c4b018_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

Genome-Wide Identification of Stable RNA Secondary Structures Across Multiple Organisms Using Chemical Probing Data: Insights into Short Structural Motifs and RNA-Targeting Therapeutics

Small molecules targeting specific RNA binding sites, including stable and transient RNA structures, are emerging as effective pharmacological approaches for modulating gene expression. However, little is understood about how stable RNA secondary structures are shared across organisms, an important factor in controlling drug selectivity. In this study, I provide an analytical pipeline named RNA Secondary Structure Finder (R2S-Finder) to discover short, stable RNA structural motifs for humans, Escherichia coli (E. coli), SARS-CoV-2, and Zika virus by leveraging existing in vivo and in vitro genome-wide chemical RNA-probing datasets. I found several common features across organisms. For example, apart from the well-documented tetraloops, AU-rich tetraloops are widely present in different organisms. I also found that the 5 untranslated region (UTR) contains a higher proportion of stable structures than the coding sequences in humans, SARS-CoV-2, and Zika virus. In general, stable structures predicted from in vitro (protein-free) and in vivo datasets are consistent in humans, E. coli, and SARS-CoV-2, indicating that most stable structure formation were driven by RNA folding alone, while a larger variation was found between in vitro and in vivo data with certain RNA types, such as human long intergenic non-coding RNAs (lincRNAs). Finally, I predicted stable three- and four-way RNA junctions that exist both in vivo and in vitro conditions, which can potentially serve as drug targets. All results of stable sequences, stem-loops, internal loops, bulges, and three- and four-way junctions have been collated in the R2S-Finder database (https://github.com/JingxinWangLab/R2S-Finder), which is coded in hyperlinked HTML pages and tabulated in CSV files.

bioinformatics↗

Continuous cell type diversification throughout the embryonic and postnatal mouse visual cortex development

The mammalian cortex is composed of a highly diverse set of cell types and develops through a series of temporally regulated events that build out the cell type and circuit foundation for cortical function. The mechanisms underlying the development of different cell types remain elusive. Single-cell transcriptomics provides the capacity to systematically study cell types across the entire temporal range of cortical development. Here, we present a comprehensive and high-resolution transcriptomic and epigenomic cell type atlas of the developing mouse visual cortex. The atlas was built from a single-cell RNA-sequencing dataset of 568,674 high-quality single-cell transcriptomes and a single-nucleus Multiome dataset of 194,545 high-quality nuclei providing both transcriptomic and chromatin accessibility profiles, densely sampled throughout the embryonic and postnatal developmental stages from E11.5 to P56. We computationally reconstructed a transcriptomic developmental trajectory map of all excitatory, inhibitory, and non-neuronal cell types in the visual cortex, identifying branching points marking the emergence of new cell types at specific developmental ages and defining molecular signatures of cellular diversification. In addition to neurogenesis, gliogenesis and early postmitotic maturation in the embryonic stage which gives rise to all the cell classes and nearly all subclasses, we find that increasingly refined cell types emerge throughout the postnatal differentiation process, including the late emergence of many cell types during the eye-opening stage (P11-P14) and the onset of critical period (P21), suggesting continuous cell type diversification at different stages of cortical development. Throughout development, we find cooperative dynamic changes in gene expression and chromatin accessibility in specific cell types, identifying both chromatin peaks potentially regulating the expression of specific genes and transcription factors potentially regulating specific peaks. Furthermore, a single gene can be regulated by multiple peaks associated with different cell types and/or different developmental stages. Collectively, our study provides the most detailed dynamic molecular map directly associated with individual cell types and specific developmental events that reveals the molecular logic underlying the continuous refinement of cell type identities in the developing visual cortex.

neuroscience↗

Gene encoding CC-NBS-LRR protein on rye chromosome 1RS confers wheat stripe rust resistance

Stripe rust, a globally widespread disease, stands as one of the most significant threats to wheat cultivation. The 1BL/1RS translocation, renowned for its robust resistance to both rust and powdery mildew, has historically played an important role in wheat breeding and production. The gene for resistance to stripe rust on the 1RS is known as Yr9 and plays an important role in the production of wheat, but over the course of long-term breeding had lost its resistance due to the evolution of stripe rust towards greater and greater virulence. In this paper, we cloned the stripe rust resistance gene, Yr9, from triticale by genetic mapping approach. The Yr9 encodes a typical nucleotide-binding leucine-rich repeat (NLR) protein. Both transgenic and overexpression of Yr9 in highly stripe rust susceptible wheat varieties conferred complete resistance to the stripe rust races CYR17 and partial resistance to the stripe rust races CYR32, CYR33, and CYR34. In addition, the Yr9 allele in the 1BL/1RS translocation line also showed the same level of resistance to stripe rust. Both two alleles loses resistance when deployed in the field or inoculated with mixed physiological races collected from the field. Our findings provide valuable insights for breeders to strategically incorporate disease resistance genes and provides a foundation for further understanding how pathogenic bacteria might evolve to evade recognition via NLR type proteins. SignificanceThe 1BL/1RS translocation between wheat and rye is the most successful case of exogenous gene application in plant genetic improvement and has been used in wheat breeding for over 50 years. Here we report the cloning of a stripe rust resistance gene Yr9 located on rye chromosome 1RS using a triticale population. The Yr9 encodes a coiled-coil nucleotide-binding site leucine-rich repeat (CC-NBS-LRR) protein that show complete resistance to the stripe rust races CYR17 and partial resistance to the stripe rust races CYR32, CYR33, and CYR34, albeit demonstrating susceptibility under field conditions. Our findings position Yr9 as an ideal candidate gene to study the mechanism of inactivation of disease resistance genes as a result of pathogen evolution.

genetics↗

Mammalian chemosensory bile acid detection supports species and gut microbiome evaluation

Long abstractThe rodent accessory olfactory system (AOS) detects environmental chemosignals and guides social and survival-oriented behaviors. Fecal bile acids activate neurons in the AOS, potentially serving as mammalian pheromones and kairomones, but few molecules in this large class have been evaluated thus far. We used live volumetric Ca2+ imaging to screen naturally occurring bile acids for their capacity to activate peripheral vomeronasal sensory neurons (VSNs). We found that taurine-conjugated bile acids (tauro-BAs), including taurine-conjugates of cholic acid, deoxycholic acid, lithocholic acid, and chenodeoxycholic acid (TCA, TDCA, TLCA, TCDCA, respectively) activate large populations of VSNs at sub-micromolar concentrations. Tauro-BA-sensitive VSNs rarely responded to unconjugated (CA, CDCA, DCA, LCA), glycine-conjugated (GCA, GDCA, GLCA, GCDCA), or keto-conjugated (7-keto DCA, 12-keto DCA, 7-keto LCA) bile acids. Tauro-BA-sensitive VSNs were also insensitive to well-studied sulfated steroids, suggesting tauro-BAs activate vomeronasal receptors that have not yet been de-orphaned. Among the tauro-BAs, TDCA displayed particularly strong potency, activating many VSNs at sub-micromolar concentrations. Tauro-BAs were not detectable in mouse fecal extracts by mass spectrometry, but were found in reptile fecal extracts and germ-free mouse fecal extracts. VSN responses to germ-free and conventional mouse fecal extracts, conjugated bile acids, and tauro-BAs revealed that non-overlapping populations of VSNs respond to germ-free and conventional mouse feces. A subset of VSNs that were activated by germ-free mouse fecal extracts responded to tauro-BAs, whereas VSNs responsive to conventionally fecal extracts responded to unconjugated bile acids. In vivo exposure to TDCA alone, and to mouse fecal extracts spiked with TDCA, elicited mild aversion and stress-associated behaviors in a non-social context (avoidance, digging, grooming, etc.). These studies establish tauro-BAs as a novel class of aversive vomeronasal ligands that vary in feces across species and gut microbiomes. Short abstractThe rodent accessory olfactory system (AOS) detects environmental chemosignals and guides social and survival-oriented behaviors. Fecal bile acids activate neurons in the AOS, but the full repertoire of bile acids that activate VSNs is not known. A live Ca2+ imaging screen revealed that VSNs were highly activated by taurine-conjugated bile acids (tauro-BAs) at sub-micromolar concentrations. Tauro-BAs were undetectable in conventionally raised mouse fecal extracts, but were found in reptile fecal extracts and germ-free mouse fecal extracts. VSN activity to tauro-BAs overlapped that of germ-free mouse fecal extracts, suggesting a link between bile acid chemosensation and the gut microbiome. When mice were exposed to taurodeoxycholic acid in vivo, they displayed mild aversion and stress-associated behaviors.

neuroscience↗

C-Reactive Protein Drives Potent Clearance of Blood Bacteria in the Liver by Activating the Complement System

Plasma C-reactive protein (CRP) is widely used as a biomarker for bacterial infections due to its massive induction during infections, however, the precise function of CRP in bacterial infections remains undefined. Here we show that CRP enables Kupffer cells (liver macrophages) to capture and eliminate a wide range of encapsulated bacteria from the bloodstream of mice and thereby provides rapid and effective immunity. Mechanistically, CRP binds to the structurally diverse capsular polysaccharides of major Gram-positive and -negative pathogens, and thereby activates complement C3 at the bacterial surface. The C3-opsonized microbes are in turn captured by C3 receptors on the surface of Kupffer cells, and eliminated in the liver sinusoids. Since CRP principally shares the functional features of antibodies in pathogen recognition/execution, CRP-based defense combines the broad spectrum of the innate immunity with the swiftness, potency and specificity of the adaptive immunity, which helps explain massive rise of CRP during systemic bacterial infections.

immunology↗

A simple action reduces food intake and obesity in mice

Diets that are high in fat cause over-eating and weight gain in multiple species of animals, suggesting that high dietary fat is sufficient to cause obesity. However, high-fat diets are typically provided freely to animals in obesity experiments, so it remains unclear if high-fat diets would still cause obesity if they required more effort to obtain. We hypothesized that unrestricted and easy access is necessary for high-fat diet induced over-eating, and the corollary that requiring mice to perform small amounts of work to obtain high-fat diet would reduce high-fat diet intake and associated weight gain. To test this hypothesis, we developed a novel home-cage based feeding device that either provided high-fat diet freely, or after mice poked their noses into a port one time - a simple action that is easy for them to do. We tested the effect of this intervention for six weeks, with mice receiving all daily calories from high-fat diet, modifying only how they accessed it. Requiring mice to nose-poke to access high-fat diet reduced intake and nearly completely prevented the development of obesity. In follow up experiments, we observed a similar phenomenon in mice responding for low-fat grain-based pellets that do not induce obesity, suggesting a general mechanism whereby animals engage with and consume more food when it is freely available vs. when it requires a simple action to obtain. We conclude that unrestricted access to food promotes overeating, and that a simple action such as a nose-poke can reduce over-eating and weight gain in mice. This may have implications for why over-eating and obesity are common in modern food environments, which are often characterized by easy access to low-cost unhealthy foods.

animal behavior and cognition↗