Biology subjects

Xie, X.

Publications and source records attributed to Xie, X..

At least 109 records · Page 6Linked to original sources

bioRxiv2024

TRIM7 ubiquitinates SARS-CoV-2 membrane protein to limit apoptosis and viral replication

SARS-CoV-2 is a highly transmissible virus that causes COVID-19 disease. Mechanisms of viral pathogenesis include excessive inflammation and viral-induced cell death, resulting in tissue damage. We identified the host E3-ubiquitin ligase TRIM7 as an inhibitor of apoptosis and SARS-CoV-2 replication via ubiquitination of the viral membrane (M) protein. Trim7-/- mice exhibited increased pathology and virus titers associated with epithelial apoptosis and dysregulated immune responses. Mechanistically, TRIM7 ubiquitinates M on K14, which protects cells from cell death. Longitudinal SARS-CoV-2 sequence analysis from infected patients revealed that mutations on M-K14 appeared in circulating variants during the pandemic. The relevance of these mutations was tested in a mouse model. A recombinant M- K14/K15R virus showed reduced viral replication, consistent with the role of K15 in virus assembly, and increased levels of apoptosis associated with the loss of ubiquitination on K14. TRIM7 antiviral activity requires caspase-6 inhibition, linking apoptosis with viral replication and pathology.

microbiology↗

bioRxiv2024

Combining Scalable Organ Chip Platform with Deep Learning-Based Imaging Analysis for Cancer Therapeutic Screening

Functional precision oncology represents an emerging approach to genomic approaches by testing treatment options directly on patient-derived models. Current assays, including the use of patient-derived xenograft (PDX) and patient-derived organoid (PDOs), faces major barriers in clinical use due to technical challenges, such as standardization, cost, assay time, scalability, and faithful mimicry of patient tumor microenvironment (TME). Here, we introduce an Organ Chip (OC) device constructed entirely from thermoplastic materials, free of porous membrane or other barrier structures, and optimized for high-content imaging (HCI). This automation-compatible device supports tissue-specific extracellular matrices and coculture for a wide spectrum of organ and disease types, including the TME. As a proof-of-concept, we demonstrate the growth of pancreatic, lung, and colon cancer cell lines and primary lung cancer cells and the testing of cancer drugs in these models. HCI-based phenotypic profiling enabled accurate quantification of drug response, with better performance than traditional biochemical assays. Moreover, we developed a deep-learning method for assessing drug responses using bright field images. The integration of a low-cost, scalable, and faithful OC models with automatic high-content image analysis represents a significant stride towards functional precision oncology and cancer drug discovery.

bioengineering↗

bioRxiv2024

Optogenetic inhibition of light-captured alcohol-taking striatal engrams facilitates extinction and suppresses reinstatement

BackgroundAlcohol use disorder (AUD) is a complex condition, and it remains unclear which specific neuronal substrates mediate alcohol-seeking and -taking behaviors. Engram cells and their related ensembles, which encode learning and memory, may play a role in this process. We aimed to assess the precise neural substrates underlying alcohol-seeking and -taking behaviors and determine how they may affect one another. MethodsUsing FLiCRE (Fast Light and Calcium-Regulated Expression; a newly developed technique which permits the trapping of acutely activated neuronal ensembles) and operant-self administration (OSA), we tagged striatal neurons activated during alcohol-taking behaviors. We used FLiCRE to express an inhibitory halorhodopsin in alcohol-taking neurons, permitting loss-of-function manipulations. ResultsWe found that the inhibition of OSA-tagged alcohol-taking neurons decreased both alcohol-seeking and -taking behaviors in future OSA trials. In addition, optogenetic inhibition of these OSA-tagged alcohol-taking neurons during extinction training facilitated the extinction of alcohol-seeking behaviors. Furthermore, inhibition of these OSA-tagged alcohol-taking neurons suppressed the reinstatement of alcohol-seeking behaviors, but, interestingly, it did not significantly suppress alcohol-taking behaviors during reinstatement. ConclusionsOur findings suggest that alcohol-taking neurons are crucial for future alcohol-seeking behaviors during extinction and reinstatement. These results may help in the development of new therapeutic approaches to enhance extinction and suppress relapse in individuals with AUD.

neuroscience↗

bioRxiv2024

Decellularized biohybrid nerve promotes motor axon projections

Developing nerve grafts with intact mesostructures, superior conductivity, minimal immunogenicity, and improved tissue integration is essential for the treatment and restoration of neurological dysfunctions. A key factor is promoting directed axon growth into the grafts. To achieve this, we developed biohybrid nerves using decellularized rat sciatic nerve modified by in situ polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). We compared nine biohybrid nerves with varying polymerization conditions and cycles, selecting the best candidate through material characterization. Our results showed that a 1:1 ratio of FeCl3 oxidant to ethylenedioxythiophene (EDOT) monomer, cycled twice, provided superior conductivity (>0.2 mS/cm), mechanical alignment, intact mesostructures, and high compatibility with cells and blood. To test the biohybrid nerves effectiveness in promoting motor axon growth, we used human Spinal Cord Spheroids (hSCSs) from HUES 3 Hb9:GFP cells, with motor axons labeled with green fluorescent protein (GFP). Seeding hSCS onto one end of the conduit allowed motor axon outgrowth into the biohybrid nerve. Our construct effectively promoted directed motor axon growth, which improved significantly after seeding the grafts with Schwann cells. This study presents a promising approach for reconstructing axonal tracts in humans.

bioengineering↗

bioRxiv2024

From gene to structure: Unraveling genomic dark matter in Ca. Accumulibacter

Candidatus Accumulibacter is a unique and pivotal genus of polyphosphate-accumulating organisms (PAOs) prevalent in wastewater treatment plants, and plays mainstay roles in the global phosphorus cycle. Whereas, the efforts toward a complete understanding of their genetic and metabolic characteristics are largely hindered by major limitations in existing sequence-based annotation methods, leaving more than half of their protein-encoding genes unannotated. To address the challenge, we developed a comprehensive approach integrating pangenome analysis, gene-based protein structure and function prediction, and metatranscriptomic analysis, extending beyond the constraints of sequence-centric methodologies. The application to Ca. Accumulibacter allowed the establishment of the pan-Ca. Accumulibacter proteome structure database, providing references for >200,000 proteins. Benchmarking on 28 Ca. Accumulibacter genomes showed major increases in the average annotation coverage from 51% to 83%. Genetic and metabolic characteristics that had eluded exploration via conventional methods were unraveled. For instance, the identification of a previously unknown phosphofructokinase gene suggests that all Ca. Accumulibacter encoded a complete Embden-Meyerhof-Parnas pathway. A previously defined homolog of phosphate-specific transport system accessory protein (PhoU) was actually an inorganic phosphate transport (Pit) accessory protein, regulating Pit instead of the high-affinity phosphate transport (Pst), a key to the emergence of the polyphosphate-accumulating trait of Ca. Accumulibacter. Additional lineage members were found encoding complete denitrification pathways. This study offers a readily usable and transferable tool for the establishment of high-coverage annotation reference databases for diverse cultured and uncultured bacteria, facilitating the exploration and understanding of genomic dark matter in the bacterial domain. SynopsisA integrated and advanced approach unraveling key genomic dark matter in Ca. Accumulibacter and readily applicable to diverse bacteria for customerized high-coverage annotation reference database establishment

genomics↗

bioRxiv2024

Modeling Repertoire Behavior within the Energy-Based Framework: A Study on Cell Proliferation and Somatic Hypermutation during the Adaptive Immune Response

Monitoring and describing the adaptive immune repertoire(IR) for disease detection and diagnosis is essential in healthcare research. Many phenomenon have been observed to generalize the static property of IR, but the mathematical description of the formation and dynamic changes of IR still lacks research. Here, we present a mathematical and physical model to interpret the cell proliferation and somatic hypermutation(SHM) process in IR, difficulties to generate different clones in IR are computed, and IR distance is calculated as the minimum effort required to transform one IR distribution to another. IR distribution and distance can be detected from samples containing 104 cells. The validity of our method is confirmed by the unsupervised clustering of data from mice spleen and clinical PBMC samples including various immune stages and diseases. Our work dynamically characterize and quantify IR process, enabling a macroscopic immunoevaluation by sensitive immune fluctuation detection from minute samples.

biophysics↗

bioRxiv2024

Asymmetric Engagement of Dimeric CRL3KBTBD4 by the Molecular Glue UM171 Licenses Degradation of HDAC1/2 Complexes

UM171 is a potent small molecule agonist of ex vivo human hematopoietic stem cell (HSC) self-renewal1, a process that is tightly controlled by epigenetic regulation. By co-opting KBTBD4, a substrate receptor of the CULLIN3-RING E3 ubiquitin ligase complex, UM171 promotes the degradation of members of the CoREST transcriptional corepressor complex, thereby limiting HSC attrition2,3. However, the direct target and mechanism of action of UM171 remain unclear. Here, we reveal that UM171 acts as a molecular glue to induce high-affinity interactions between KBTBD4 and HDAC1 to promote the degradation of select HDAC1/2 corepressor complexes. Through proteomics and chemical inhibitor studies, we discover that the principal target of UM171 is HDAC1/2. Cryo-electron microscopy (cryo-EM) analysis of dimeric KBTBD4 bound to UM171 and the LSD1-HDAC1-CoREST complex unveils an unexpected asymmetric assembly, in which a single UM171 molecule enables a pair of KBTBD4 KELCH-repeat propeller domains to recruit HDAC1 by clamping on its catalytic domain. One of the KBTBD4 propellers partially masks the rim of the HDAC1 active site pocket, which is exploited by UM171 to extend the E3-neo-substrate interface. The other propeller cooperatively strengthens HDAC1 binding via a separate and distinct interface. The overall neomorphic interaction is further buttressed by an endogenous cofactor of HDAC1-CoREST, inositol hexakisphosphate, which makes direct contacts with KBTBD4 and acts as a second molecular glue. The functional relevance of the quaternary complex interaction surfaces defined by cryo-EM is demonstrated by in situ base editor scanning of KBTBD4 and HDAC1. By delineating the direct target of UM171 and its mechanism of action, our results reveal how the cooperativity offered by a large dimeric CRL E3 family can be leveraged by a small molecule degrader and establish for the first time a dual molecular glue paradigm.

molecular biology↗

bioRxiv2024

KBTBD4 Cancer Hotspot Mutations Drive Neomorphic Degradation of HDAC1/2 Corepressor Complexes

Cancer mutations can create neomorphic protein-protein interactions to drive aberrant function1. As a substrate receptor of the CULLIN3-RBX1 E3 ubiquitin ligase complex, KBTBD4 is recurrently mutated in medulloblastoma (MB)2, the most common embryonal brain tumor in children, and pineoblastoma3. These mutations impart gain-of-function to KBTBD4 to induce aberrant degradation of the transcriptional corepressor CoREST4. However, their mechanism of action remains unresolved. Here, we elucidate the mechanistic basis by which KBTBD4 mutations promote CoREST degradation through engaging HDAC1/2, the direct neomorphic target of the substrate receptor. Using deep mutational scanning, we systematically map the mutational landscape of the KBTBD4 cancer hotspot, revealing distinct preferences by which insertions and substitutions can promote gain-of-function and the critical residues involved in the hotspot interaction. Cryo-electron microscopy (cryo-EM) analysis of two distinct KBTBD4 cancer mutants bound to LSD1-HDAC1-CoREST reveals that a KBTBD4 homodimer asymmetrically engages HDAC1 with two KELCH-repeat propeller domains. The interface between HDAC1 and one of the KBTBD4 propellers is stabilized by the MB mutations, which directly insert a bulky side chain into the active site pocket of HDAC1. Our structural and mutational analyses inform how this hotspot E3-neo-substrate interface can be chemically modulated. First, our results unveil a converging shape complementarity-based mechanism between gain-of-function E3 mutations and a molecular glue degrader, UM171. Second, we demonstrate that HDAC1/2 inhibitors can block the mutant KBTBD4-HDAC1 interface, the aberrant degradation of CoREST, and the growth of KBTBD4-mutant MB models. Altogether, our work reveals the structural and mechanistic basis of cancer mutation-driven neomorphic protein-protein interactions and pharmacological strategies to modulate their action for therapeutic applications.

molecular biology↗

bioRxiv2024

Axo-axonic synaptic input drives homeostatic plasticity by tuning the axon initial segment structurally and functionally

The stability of functional brain network is maintained by homeostatic plasticity, which restores equilibrium following perturbation. As the initiation site of action potentials, the axon initial segment (AIS) of glutamatergic projection neurons (PyNs) undergoes dynamic adjustment that exerts powerful control over neuronal firing properties in response to changes in network states. Although AIS plasticity has been reported to be coupled with the changes of network activity, it is poorly understood whether it involves direct synaptic input to the AIS. Here we show that changes of GABAergic synaptic input to the AIS of cortical PyNs, specifically from chandelier cells (ChCs), are sufficient to drive homeostatic tuning of the AIS within 1-2 weeks, while those from parvalbumin-positive basket cells do not. This tuning is reflected in the morphology of the AIS, the expression level of voltage-gated sodium channels, and the intrinsic neuronal excitability of PyNs. Interestingly, the timing of AIS tuning in PyNs of the prefrontal cortex corresponds to the recovery of changes in social behavior caused by alterations of ChC synaptic transmission. Thus, homeostatic plasticity of the AIS at postsynaptic PyNs may counteract deficits elicited by imbalanced ChC presynaptic input. TeaserAxon initial segment dynamically responds to changes in local input from chandelier cells to prevent abnormal neuronal functions.

neuroscience↗

bioRxiv2024

Whole-genome resequencing revealed the Origin and Domestication of Chinese Domestic Rabbits

The evolutionary and genetic origins of Chinese indigenous rabbits (Oryctolagus cuniculus) remain largely unclear, despite being among the most recently domesticated animals. We sequenced the whole genomes of 142 individual rabbits and collected 25 resequencing accessions from the NCBI, representing six Chinese indigenous breeds, three other domesticated breeds (serving as a bridge between European wild-type and Chinese domestic populations), and two wild rabbit populations from the Iberian Peninsula and Southern France. Population and demographic analyses suggest that Chinese domestic rabbits are most likely descendants of O. c. cuniculus, native to France 800-1500 years ago. These rabbits likely first arrived in the southeast coastal areas of China through trade before spreading to inland regions. Additionally, there may be other origins for Chinese domestic rabbits. We observed considerable variation in the genetic makeup of maternal ancestry between Chinese domestic rabbits and European wild populations, with Chinese rabbits possessing unique mitochondrial haplotypes. Our analysis also highlights selective sweeps on genes affecting brain and neuronal development, which may have been under strong positive selection during domestication; genes related to starch digestion and fat metabolism, suggesting an evolutionary adaptation to digest high-starch diets; and the white coat phenotype in rabbits, resulting from selection at the melanogenesis-associated transcription factor locus. Overall, our data provide comprehensive insights into the origin and domestication of rabbits and lay the foundation for genome-based breeding.

evolutionary biology↗

bioRxiv2024

LncRNA-Snhg3 Aggravates Hepatic Steatosis by Regulating PPARγ via SND1/H3K27me3

LncRNAs are involved in modulating the individual risk and the severity of progression in metabolic dysfunction-associated fatty liver disease (MASLD), but their precise roles remain largely unknown. This study aimed to investigate the role of lncRNA Snhg3 in the development and progression of MASLD, along with the underlying mechanisms. The result showed that Snhg3 was significantly downregulated in the liver of high-fat diet-induced obesity (DIO) mice. Notably, palmitic acid promoted the expression of Snhg3 and overexpression of Snhg3 increased lipid accumulation in primary hepatocytes. Furthermore, hepatocyte-specific Snhg3 deficiency decreased body and liver weight, alleviated hepatic steatosis and promoted hepatic fatty acid metabolism in DIO mice, whereas overexpression induced the opposite effect. Mechanistically, Snhg3 promoted the expression, stability and nuclear localization of SND1 protein via interacting with SND1, thereby inducing K63-linked ubiquitination modification of SND1. Moreover, Snhg3 decreased the H3K27me3 level and induced SND1-mediated chromatin loose remodeling, thus reducing H3K27me3 enrichment at the Ppar{gamma} promoter and enhancing Ppar{gamma} expression. The administration of PPAR{gamma} antagonist T0070907 improved Snhg3-aggravated hepatic steatosis. Our study revealed a new signaling pathway, Snhg3/SND1/H3K27me3/PPAR{gamma}, responsible for MASLD and indicates that lncRNA-mediated epigenetic modification has a crucial role in the pathology of MASLD.

molecular biology↗

bioRxiv2024

Multi-layered Network Analysis of Osteoking in the Treatment of Osteoporosis: Unraveling Mechanisms from Gene Expression to Molecular Docking

This study aimed to elucidate the therapeutic mechanisms of Osteoking in the treatment of osteoporosis through a comprehensive analysis of potential targets, active ingredients, and associated pathways. MethodThe study employed an integrated approach to understand the molecular mechanisms underlying Osteokings treatment of osteoporosis. The construction of the protein-protein interaction network involved analyzing data from GENEMANIA and STRING databases. KEGG enrichment analysis was performed to identify enriched pathways, focusing on the cAMP signaling and PI3K-AKT signaling pathways. Active ingredients, disease targets, and osteoporosis-related pathways were integrated into a comprehensive network diagram using Cytoscape. ResultThe Gene Expression Omnibus (GEO) database was employed to identify osteoporosis-related gene targets, revealing 3,578 downregulated and 1,204 upregulated genes. Simultaneously, Osteokings active ingredients and potential targets were investigated using the Traditional Chinese Medicine Integrated Database (ETCM). A protein-protein interaction network and KEGG pathway enrichment analysis were constructed, highlighting potential targets for Osteokings therapeutic effects on osteoporosis. The study also conducted molecular docking analysis, revealing the strong binding capacities of Kaempferol with key disease targets. The results suggest that Osteoking, particularly its active component Kaempferol, holds promise as a potential intervention for osteoporosis, providing insights for further exploration and development of osteoporosis treatments ConclusionsIn conclusion, despite some limitations, this study provides valuable information for the treatment of osteoporosis. Future research should make further progress by continually expanding data sources, conducting in-depth experimental validations, and broadening the scope of targets to better understand and address this common skeletal disorder. FundingThis work was supported by the Scientific Foundation of Fuzhou Municipal Health Commission (2021-S-wp3).

bioinformatics↗

bioRxiv2024

Targeting G9a translational mechanism of SARS-CoV-2 pathogenesis for multifaceted therapeutics of COVID-19 and its sequalae

By largely unknown mechanism(s), SARS-CoV-2 hijacks the host translation apparatus to promote COVID-19 pathogenesis. We report that the histone methyltransferase G9a noncanonically regulates viral hijacking of the translation machinery to bring about COVID-19 symptoms of hyperinflammation, lymphopenia, and blood coagulation. Chemoproteomic analysis of COVID-19 patient peripheral mononuclear blood cells (PBMC) identified enhanced interactions between SARS-CoV-2-upregulated G9a and distinct translation regulators, particularly the N6-methyladenosine (m6A) RNA methylase METTL3. These interactions with translation regulators implicated G9a in translational regulation of COVID-19. Inhibition of G9a activity suppressed SARS-CoV-2 replication in human alveolar epithelial cells. Accordingly, multi-omics analysis of the same alveolar cells identified SARS-CoV-2-induced changes at the transcriptional, m6A-epitranscriptional, translational, and post-translational (phosphorylation or secretion) levels that were reversed by inhibitor treatment. As suggested by the aforesaid chemoproteomic analysis, these multi-omics-correlated changes revealed a G9a-regulated translational mechanism of COVID-19 pathogenesis in which G9a directs translation of viral and host proteins associated with SARS-CoV-2 replication and with dysregulation of host response. Comparison of proteomic analyses of G9a inhibitor-treated, SARS-CoV-2 infected cells, or ex vivo culture of patient PBMCs, with COVID-19 patient data revealed that G9a inhibition reversed the patient proteomic landscape that correlated with COVID-19 pathology/symptoms. These data also indicated that the G9a-regulated, inhibitor-reversed, translational mechanism outperformed G9a-transcriptional suppression to ultimately determine COVID-19 pathogenesis and to define the inhibitor action, from which biomarkers of serve symptom vulnerability were mechanistically derived. This cell line-to-patient conservation of G9a-translated, COVID-19 proteome suggests that G9a inhibitors can be used to treat patients with COVID-19, particularly patients with long-lasting COVID-19 sequelae.

immunology↗

bioRxiv2024

IL-1beta-induced epithelial cell and fibroblast transdifferentiation fuels neutrophil recruitment in chronic rhinosinusitis with nasal polyps

Neutrophilic inflammation contributes to multiple chronic inflammatory airway diseases, including asthma and chronic rhinosinusitis with nasal polyps (CRSwNP), and is associated with an unfavorable prognosis. Here, using single-cell RNA sequencing (scRNA-seq) to profile human nasal mucosa obtained from the inferior turbinates, middle turbinates, and nasal polyps of CRSwNP patients, we identified two IL-1 signaling-induced cell subsets--LY6D+ club cells and IDO1+ fibroblasts--that promote neutrophil recruitment by respectively releasing S100A8/A9 and CXCL1/2/3/5/6/8 into inflammatory regions. IL-1{beta}, a pro-inflammatory cytokine involved in IL-1 signaling, induces the transdifferentiation of LY6D+ club cells and IDO1+ fibroblasts from primary epithelial cells and fibroblasts, respectively. In an LPS-induced neutrophilic CRSwNP mouse model, blocking IL-1{beta} activity with a receptor antagonist significantly reduced the numbers of LY6D+ club cells and IDO1+ fibroblasts and mitigated nasal inflammation. This study reveals the roles of two cell subsets in neutrophil recruitment and demonstrates an IL-1-based intervention for mitigating neutrophilic inflammation in CRSwNP.

immunology↗

bioRxiv2024

Neutralizing gut-derived lipopolysaccharide as a novel therapeutic strategy for severe leptospirosis

Leptospirosis is an emerging infectious disease caused by pathogenic Leptospira spp. Humans and some mammals can develop severe forms of leptospirosis accompanied by a dysregulated inflammatory response, which often results in death. The gut microbiota has been increasingly recognized as a vital element in systemic health. However, the precise role of the gut microbiota in severe leptospirosis is still unknown. Here, we aimed to explore the function and potential mechanisms of the gut microbiota in a hamster model of severe leptospirosis. Our study showed that leptospires were able to multiply in the intestine, cause pathological injury, and induce intestinal and systemic inflammatory responses. 16S rRNA gene sequencing analysis revealed that Leptospira infection changed the composition of the gut microbiota of hamsters with an expansion of Proteobacteria. In addition, gut barrier permeability was increased after infection, as reflected by a decrease in the expression of tight junctions. Translocated Proteobacteria were found in the intestinal epithelium of moribund hamsters, as determined by fluorescence in situ hybridization, with elevated LPS levels in the serum. Moreover, gut microbiota depletion reduced the survival time, increased the leptospiral load, and promoted the expression of proinflammatory cytokines after Leptospira infection. Intriguingly, fecal filtration and serum from moribund hamsters both increased the transcription of TNF-, IL-1{beta}, IL-10, and TLR4 in macrophages compared with those from uninfected hamsters. These stimulating activities were inhibited by LPS neutralization using polymyxin B. Based on our findings, we identified an LPS neutralization therapy that significantly improved the survival rates in severe leptospirosis when used in combination with antibiotic therapy or polyclonal antibody therapy. In conclusion, our study not only uncovers the role of the gut microbiota in severe leptospirosis but also provides a therapeutic strategy for severe leptospirosis.

microbiology↗

bioRxiv2023

Activating SRC/MAPK signaling via 5-HT1A receptor contributes to the effect of vilazodone on improving thrombocytopenia

Thrombocytopenia caused by long-term radiotherapy and chemotherapy exists in cancer treatment. Previous research demonstrates that 5-Hydroxtrayptamine (5-HT) and its receptors induces the formation of megakaryocytes (MKs) and platelets. However, the relationships between 5-HT1A receptor (5-HTR1A) and MKs is unclear so far. We screened and investigated the mechanism of vilazodone as a 5-HTR1A partial agonist in promoting MK differentiation and evaluated its therapeutic effect in thrombocytopenia. We employed a drug screening model based on machine learning (ML) to screen the megakaryocytopoiesis activity of VLZ. The effects of Vilazodone (VLZ) on megakaryocytopoiesis were verified in HEL and Meg-01 cells. Tg (itga2b: eGFP) zebrafish was performed to analyze the alterations in thrombopoiesis. Moreover, we established a thrombocytopenia mice model to investigate VLZ administration accelerates platelet recovery and function. We carried out network pharmacology, Western blot and immunofluorescence to demonstrate the potential targets and pathway of VLZ. VLZ has been predicted to have a potential biological action. Meanwhile, VLZ administration promotes MK differentiation and thrombopoiesis in cells and zebrafish models. Progressive experiments showed that VLZ has a potential therapeutic effect on radiation-induced thrombocytopenia in vivo. The network pharmacology and associated mechanism study indicated that SRC and MAPK signaling are both involved in the processes of megakaryopoiesis facilitated by VLZ. Furthermore, the expression of 5-HTR1A during megakaryocyte differentiation is closely related to the activation of SRC and MAPK. Our findings demonstrated that the expression of 5-HTR1A on MK, VLZ could bind to the 5-HTR1A receptor and further regulate the SRC/MAPK signaling pathway to facilitate megakaryocyte differentiation and platelet production, which provides new insights into the alternative therapeutic options for thrombocytopenia.

pharmacology and toxicology↗

bioRxiv2023

Structure basis for recognition of 26RFa by the pyroglutamylated RFamide peptide receptor

The neuropeptide 26RFa, a member of the RF-amide peptide family, activates the pyroglutamylated RF-amide peptide receptor (QRFPR), a class A GPCR. The 26RFa/QRFPR system plays critical roles in energy homeostasis, making QRFPR an attractive drug target for treating obesity, diabetes, and eating disorders. However, the lack of structural information has hindered our understanding of the peptide recognition and regulatory mechanism of QRFPR, impeding drug design efforts. In this study, we determined the cryo-EM structure of the Gq-coupled QRFPR bound to 26RFa. The structure reveals a unique assembly mode of the receptor extracellular regions and the peptide N-terminus and elucidates the recognition mechanism of the C-terminal heptapeptide of 26RFa within the transmembrane binding pocket of QRFPR. The study also clarifies the similarities and distinctions in the binding pattern of the RF-amide moiety in five RF-amide peptides and the RY-amide segment in neuropeptide Y. These findings deepen our understanding of the RF-amide peptides recognition, aiding in the rational design of drugs targeting QRFPR and other RF-amide receptors.

biophysics↗

bioRxiv2023

Dynamic Responses of Striatal Cholinergic Interneurons Control the Extinction and Updating of Goal-Directed Learning

Striatal cholinergic interneurons (CINs) regulate behavioral flexibility, but their exact contribution to this process remains elusive. In this study, we report that extinction learning enhances acetylcholine (ACh) release. Mimicking this enhancement by optogenetically inducing CIN burst firing promotes extinction learning. CINs receive excitatory thalamic inputs, and we observed that extinction training augmented thalamic activity. Optogenetically stimulating these thalamic inputs caused CIN burst firing and enhanced ACh release, strengthening extinction learning. Notably, CIN burst firing is usually followed by a pause in firing. We found that disrupting this pause through continuous optogenetic stimulation reversibly impaired the updating of goal-directed behaviors. Furthermore, excessive alcohol consumption reduced thalamus-induced burst-pause firing in CINs and impaired the reversal of goal-directed learning. In summary, thalamic-driven CIN burst firing promotes extinction learning, while the pause is pivotal for reversing goal-directed behavior, a process impacted by excessive alcohol. These findings shed light on how CINs dynamic responses affect behavioral flexibility. HighlightsH1. Burst firing of CINs promotes extinction learning H2. Thalamic-CIN excitation enhances extinction learning H3. Pause of CIN is critical for the reversal of goal-directed learning H4. Chronic alcohol consumption reduces the burst-pause of CINs and impairs the reversal of goal-directed learning.

neuroscience↗