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Liu, L.

Publications and source records attributed to Liu, L..

At least 307 records · Page 17Linked to original sources

Curcumin attenuates microglia-mediated chronic neuropathic pain through CDK5 /p35 signaling pathway

Curcumin is a phenolic compound derived from turmeric, one of the main ingredients of curry powder, which is widely used for its antioxidant, anti-inflammatory and immunomodulatory effects. Curcumin has been reported to help relieve pain, such as neuropathic pain caused by injury or disease, but the specific mechanism of its antinociceptive effect on pathological pain is unclear. Cyclin-dependent kinase 5 (Cdk5) is a key control point for the release of neurotransmitters from presynaptic vesicles. Cdk5 and its activator p35 couple to regulate key signaling cascades, thereby participating in the pain process. In this study, we established a NP model by chronic constriction injury (CCI) of the bilateral sciatic nerve in rats and evaluated behavioral hyperalgesia using mechanical and hot and cold tests. Protein expression and distribution were evaluated using western blotting and immunofluorescence. The results showed that Iba-1 and Cdk5/p35 were co-localized in the dorsal horn and dorsal root ganglia, respectively. After CCI, the expression of Cdk5 and p35 was upregulated in the dorsal horn and dorsal root ganglia, while intraperitoneal injection of curcumin significantly reversed the activation of Cdk5/p35 protein and alleviated the hyperalgesia in rats. In addition, the injection of curcumin reduced the co-localization expression of Iba-1 and Cdk5/p35, indicating that curcumin inhibited the activation of Cdk5/p35 protein in the dorsal horn and dorsal root ganglia, thereby affecting the activation of microglia, thereby having a destructive effect on the neuronal cell plasticity and synaptic structure remodeling in the development of NP. Our study provides new evidence that Cdk5/p35 in the dorsal horn and dorsal root ganglia is related to the occurrence of NP, introduces microglia as the basis for the long-term maintenance of NP, and provides insights into the molecular mechanisms involved in the analgesic effect of curcumin. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=188 SRC="FIGDIR/small/623498v1_ufig1.gif" ALT="Figure 1"> View larger version (80K): org.highwire.dtl.DTLVardef@125fc20org.highwire.dtl.DTLVardef@cba7d3org.highwire.dtl.DTLVardef@772291org.highwire.dtl.DTLVardef@17e87e3_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

PNPLA3-I148M is a Neomorph that Interferes with Two Primary Hepatic Triglyceride Clearance Pathways

A common variant of PNPLA3, encoding PNPLA3-I148M, is the most significant genetic determinant of fatty liver disease worldwide. However, it is unclear precisely how PNPLA3-I148M drives disease risk. Here, we show that endogenous human PNPLA3-I148M impairs secretion of Apolipoprotein B (ApoB), the scaffolding protein of very low-density lipoproteins (VLDLs), from hepatocytes. This is not due to a generalized secretory pathway defect, nor is it equivalent to loss of function of PNPLA3. The VLDL secretory defect is conserved in mice expressing human I148M. Untargeted lipidomics reveal that I148M human cells are enriched in polyunsaturated fatty acid (PUFA)-containing triglycerides at the expense of PUFA-containing phosphatidylcholine, causing reduced membrane dynamics, concomitantly hindering biogenesis of secreted VLDLs. ApoB secretion is substantially rescued in I148M cells that overexpress ABHD5/CGI-58, an I148M binding partner that activates lipolysis by ATGL/PNPLA2 when not bound to I148M. Conversely, knocking down CGI-58 or PNPLA2 mimics I148M. We propose that neomorphic PNPLA3-I148M exacerbates fatty liver risk by simultaneously impeding two major CGI-58-dependent pathways for liver triglyceride clearance: lipolysis and secretion.

cell biology↗

SenSeqNet: A Deep Learning Framework for Cellular Senescence Detection from Protein Sequences

Cellular senescence, characterized by the irreversible cessation of division in normally proliferating cells due to various stressors, presents a significant challenge in the treatment of age-related diseases. Understanding and accurately detecting cellular senescence is crucial for identifying potential therapeutic targets. However, traditional wet lab assays for detecting cellular senescence are time-consuming and labor-intensive, limiting research and drug development efficiency. There is an urgent need for computational tools allowing swift and accurate detection of cellular senescence from protein sequences. We propose SenSeqNet, a novel deep learning framework for detecting cellular senescence directly from protein sequences. The framework begins with feature extraction using the Evolutionarily Scaled Model (ESM-2), a state-of-the-art protein language model that captures evolutionary information and complex sequence patterns. The extracted embeddings are then passed through a hybrid architecture consisting of long short-term memory (LSTM) networks and convolutional neural networks (CNNs) to further refine and learn from the embedded information. SenSeqNet achieved a final accuracy of 83.55% on independent testing, surpassing various machine learning and deep learning architectures. This performance underscoring the robustness and effectiveness of SenSeqNet for detecting cellular senescence from protein sequences. These results provide a solid foundation for future research on aging and age-related therapeutics.

bioinformatics↗

Tools for intersectional optical and chemical tagging on cell surfaces

We present versatile tools for intersectional optical and chemical tagging of live cells. Photocaged tetrazines serve as "photo-click" adapters between recognition groups on the cell surface and diverse chemical payloads. We describe two new functionalized photocaged tetrazine structures which add a light-gating step to three common cell-targeting chemical methods: HaloTag/chloroalkane labeling, nonspecific primary amine labeling, and antibody labeling. We demonstrate light-gated versions of these three techniques in live cultured cells. We then explore two applications: monitoring tissue flows on the surface of developing zebrafish embryos, and combinatorial multicolor labeling and sorting of optically defined groups of cells. Photo-click adapters add optical control to cell tagging schemes, with modularity in both tag and cell attachment chemistry.

molecular biology↗

Genomic diversity and underlying metabolic variations of the human gut microbiome between populations at single nucleotide resolution

BackgroundA comprehensive and representative reference database is crucial for accurate taxonomic and functional profiling of the human gut microbiome in population-level studies. However, with 70% of current microbial reference data derived from Europeans and the Americans, East Asia, especially China, remain underrepresented. MethodsWe constructed the human Gut Microbiome Reference (GMR), comprising 478,588 high-quality microbial genomes from Chinese (247,134) and non-Chinese (231,454) populations. Species-level clustering and protein annotations were performed to characterize microbial diversity and function. We further integrated novel genomes into taxonomic profiling database and validated the improvements using independent cohort data. ResultsThe GMR dataset spans 6,664 species, including 26.4% newly classified species, and encodes over 20 million unique proteins, with 47% lacking known functional annotations. Notably, we observed that 35.35% and 32.46% of species unique to Chinese and non-Chinese populations, respectively. For 2,145 species shared between populations, 74% of 304 species with balanced prevalence between populations exhibited population-specific phylogenetic stratification, involving health relevant functionalities such as antibiotic resistance. Integration of novel genomes into taxonomic improved population-level species profiling by up to 23% and uncovered replicable associations between novel species and host physiological traits. ConclusionsOur study largely expands the compositional and functional landscape of the human gut microbiome, providing a crucial resource for studying the role of gut microbiome for regional health disparities.

genomics↗

Deletion of Zyxin Reduces Endothelial Inflammation and Mitigates Atherosclerosis

BACKGROUNDOscillatory shear stress (OSS)-induced endothelial inflammation plays a critical role in the pathogenesis of atherosclerosis. However, the involvement of endothelial zyxin, a mechanosensor, in OSS-associated atherosclerosis and its underlying mechanisms remains unclear. METHODSTo investigate the role of zyxin in vivo, ZyxiniECKOApoE-/- mice were utilized in atherosclerosis model induced by carotid artery ligation; in vitro, endothelial cells were subjected to disturbed flow in Ibidi systerm. RESULTSZyxin was significantly upregulated in the OSS regions of both human and mouse arteries. The specific deletion of zyxin in endothelial cells (ECs) in ApoE-/- (ZyxiniECKOApoE-/-) mice reversed the ECs activation and atherosclerosis induced by OSS. In vitro studies indicated that the absence of zyxin reduced the induction of adhesion molecules and pro-inflammatory cytokines stimulated by OSS. Mechanistic investigations demonstrated that 14-3-3{beta} facilitated yes-associated protein (YAP) phosphorylation at Serine 127, which played a critical role in retaining YAP within the cytoplasm. Under OSS stimulation, zyxin inhibited the phosphorylation of YAP at Serine 127 through its interaction with 14-3-3{beta}, rather than direct regulation of YAP. This inhibition enhanced YAPs nuclear translocation and promoted endothelial inflammation. Furthermore, it was shown that rosuvastatin inhibited zyxin expression in human umbilical vein endothelial cells and the vascular endothelium of ApoE-/- mice. This inhibition led to decreased levels of inflammatory markers and adhesion molecules associated with atherosclerotic lesions observed in the partially ligated left common carotid arteries of ApoE-/- mice. CONCLUSIONSThis study further confirms that zyxin is a mechanoreceptor in endothelial cells and elucidates the indispensable role of the zyxin-14-3-3{beta}-YAP axis in endothelial inflammation and atherogenesis. This indicates that Zyxin plays a crucial role in protecting against atherosclerosis.

cell biology↗

Three cytochrome P450 enzymes catalyse the formation of furanoclerodane precursors in Salvia spp.

Salvia species native to the Americas are rich in valuable bioactive furanoclerodanes, like the psychoactive salvinorin A found in Salvia divinorum, which is used in treatment of opioid addiction. However, there is relatively little known about their biosynthesis. To address this, we investigated the biosynthesis of salviarin, the simplest furanoclerodane structure in the ornamental sage Salvia splendens. Using a self-organizing map and mutual rank analysis of RNA-seq co-expression data, we identified three cytochrome P450 enzymes responsible for converting kolavenol into salviarin precursors, consecutively: annonene, hardwickiic acid and hautriwaic acid. As annonene and hardwickiic acid have also been proposed as intermediates in the biosynthesis of salvinorin A, and to examine our hypothesis for common evolutionary origin of the furanoclerodane pathway between the two Salvia species, we searched for homologous genes in available data for S. divinorum. The enzymes encoded by orthologous genes from S. divinorum displayed kolavenol synthase (SdKLS), annonene synthase (SdANS), and hardwickiic acid synthase (SdHDAS) activity respectively, supporting the view that these are intermediate steps in the biosynthesis of salvinorin A. We investigated the origin of annonene synthase and the role of gene duplication in the evolution of this specific activity. Our work shows how S. splendens can serve as a model species for studying furanoclerodanes biosynthesis in Salvia species, contributes to understanding the evolution of specialized metabolism in plants, and provides new tools to produce salvinorin A in biotechnological chassis.

plant biology↗

RIPK2 is crucial for the microglial inflammatory response to bacterial muramyl dipeptide but not to lipopolysaccharide

Receptor-interacting serine/threonine protein kinase 2 (RIPK2) is a kinase that plays an essential role in the modulation of innate and adaptive immune responses. As a downstream signaling molecule for nucleotide-binding oligomerization domain 1 (NOD1), NOD2, and Toll-like receptors (TLRs), it is implicated in the signaling triggered by recognition of microbe-associated molecular patterns by NOD1/2 and TLRs. Upon activation of these innate immune receptors, RIPK2 mediates the release of pro-inflammatory factors by activating mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-{kappa}B). However, whether RIPK2 is essential for downstream inflammatory signaling following the activation of NOD1/2, TLRs, or both remains controversial. In this study, we examined the role of RIPK2 in NOD2- and TLR4-dependent signaling cascades following stimulation of microglial cells with bacterial muramyl dipeptide (MDP), a NOD2 agonist, or lipopolysaccharide (LPS), a TLR4 agonist. We utilized a highly specific proteolysis targeting chimera (PROTAC) molecule, GSK3728857A, and found dramatic degradation of RIPK2 in a concentration- and time-dependent manner. Importantly, the PROTAC completely abolished MDP-induced increases in iNOS and COX-2 protein levels and pro-inflammatory gene transcription of Nos2, Ptgs2, Il-1{beta}, Tnf, Il6, Ccl2, and Mmp9. However, increases in iNOS and COX-2 proteins and pro-inflammatory gene transcription induced by the TLR4 agonist, LPS, were only slightly attenuated with the GSK3728857A pretreatment. Further findings revealed that the RIPK2 PROTAC completely blocked the phosphorylation and activation of p65 NF-{kappa}B and p38 MAPK induced by MDP, but it had no effects on the phosphorylation of these two mediators triggered by LPS. Collectively, our findings strongly suggest that RIPK2 plays an essential role in the inflammatory responses of microglia to bacterial MDP but not to LPS.

neuroscience↗

Deciphering gene regulatory programs in mouse embryonic skin through single-cell multiomics analysis

BackgroundCell type-specific transcriptional heterogeneity in embryonic mouse skin is well-documented, but few studies have investigated the regulatory mechanisms. ResultsHere, we present high throughput single-cell chromatin accessibility and transcriptome sequencing (HT-scCAT-seq), a method that simultaneously profiles transcriptome and chromatin accessibility. We utilized HT-scCAT-seq to dissect the gene regulatory mechanism governing epidermal stratification, periderm terminal differentiation, and fibroblast specification. ConclusionsBy linking chromatin accessibility to gene expression, we identified candidate cis-regulatory elements (cCREs) and target genes crucial for dermal and epidermal development. We described cells with similar gene expression profiles that exhibit distinct chromatin accessibility statuses during periderm terminal differentiation. Finally, we characterized the underlying lineage-determining transcription factors (TFs), and demonstrated that ALX4 and RUNX2 were candidate TF regulators of the dermal papilla lineage development through in silico perturbation analysis.

developmental biology↗

Reconstruct a Connectome of Single Neurons in Mouse Brains by Cross-Validating Multi-Scale Multi-Modality Data

Brain networks, often referred to as connectomes, are crucial to findings in brain science and have inspired the development of numerous technologies at macro-, meso-, and micro-scales. With the growing prevalence of single-cell analysis, there is an urgency to generate connectomes of individual neurons that project to brain-wide regions. This work reports a scalable approach to build neuron connection networks of mouse brains by mapping whole-brain single-neuron connectivity using two complementary methods at sub-neuronal levels. We first generated an arbor-net by partitioning and probabilistically pairing dendritic and axonal arbors of 20,247 neurons registered to the Allen Brain Atlas. We also produced a bouton-net based on 2.57 million putative boutons detected along single axons of 1,877 fully reconstructed neurons and probabilistic pairing of these full-morphology datasets. Our cross-validation of both the arbor-net and bouton-net showed statistical consistency in the spatially and anatomically modular distributions of neuronal connections, which also corresponded to functional modules of the mouse brain. Our single-neuron connections were also validated by two existing independent connectomes of coarser resolution based on viral tracing of neuron populations and barcoding-and-sequencing, as well as an independent synaptome containing the relative density distribution of synapses. We further found that single neuronal connections correlated more strongly with gene co-expression at both the brain region and single-cell levels than the previous full-brain mesoscale connectome of a mouse brain. Our findings allow the assembly of a new whole-brain scale single-neuron resolution connectome for all brain regions, called SEU-net. We studied the properties of our connectomes in comparison with other potential brain architectures and found a series of non-random subnetwork patterns in the form of consistent triad motifs. Overall, our data indicate a rich granularity and strong modular diversity in the brain networks of mice.

neuroscience↗

Multi-omics analysis reveals the mechanism of BnC07MYB3a is involved in seed coat color in Brassica napus L.

In rapeseed (Brassica napus), yellow-seeded varieties accumulate less flavonoid pigments (anthocyanins/proanthocyanidins) in their seed coats compared with black-seeded varieties. The yellow-seeded trait is associated with greatly improved seed oil yield, quality, and commercial value. Many R2R3 MYB activators have been characterized in rapeseed, but how MYB-type repressors affect pigment biosynthesis is not yet fully understood. In this study, we performed transcriptome sequencing and metabolomic analysis of B. napus varieties with extreme differences in seed coat color, combined with weighted gene co-expression network analysis. This analysis identified an R2R3-MYB-type transcription factor, BnC07MYB3a (BnaC07G0178800ZS), as a candidate regulator of the yellow-seeded trait in B. napus. Overexpressing BnC07MYB3a in Arabidopsis thaliana and B. napus downregulated the expression of flavonoid biosynthetic genes, resulting in significantly lower anthocyanin and proanthocyanidin accumulation than in the wild-type and a lighter seed coat color in transgenic plants. BnC07MYB3a directly binds to the promoter of the TRANSPARENT TESTA (TT) gene BnTT6 and represses its expression. BnC07MYB3a also physically interacts with BnA06bHLH92a and the WD40 transcription factor TRANSPARENT TESTA GLABRA1 (BnTTG1), suggesting that they might form a previously unidentified MYB-bHLH-WD40 transcription factor complex. Our results reveal the molecular mechanism and regulatory network of BnC07MYB3a in determining seed coat color in B. napus and provide a genetic resource for breeding yellow-seeded cultivars of B. napus.

molecular biology↗

Mechanistic Insights into the Stimulation of the Histone H3K9 Methyltransferase Clr4 by Proximal H3K14 Ubiquitination

H3K9 methylation is an evolutionarily conserved hallmark of heterochromatin and plays crucial roles in chromosome segregation, genome stability, and gene expression regulation. Clr4 is the sole histone methyltransferase responsible for catalyzing H3K9 methylation in Schizosaccharomyces pombe. Clr4 K455/K472 automethylation and histone H3K14 ubiquitination (H3K14Ub) are vital activators of the catalytic activity of Clr4, ensuring appropriate heterochromatin deposition and preventing deleterious gene silencing. While the mechanism by which automethylation activates Clr4 was recently elucidated, the mechanism of the significantly pronounced stimulatory effect of H3K14Ub on Clr4 remains unclear. Here we determined the crystal structures of Clr4 bound to ubiquitinated and unmodified H3 peptides at resolutions of 2.60 [A] and 2.39 [A], respectively. Our structures reveal a synergistic mechanism underlying the stronger stimulatory effect by H3K14Ub compared to automethylation: site-specific ubiquitination constrained by the H3K14 linkage increases substrate affinity through multivalent interactions between ubiquitin and Clr4. Additionally, H3K14Ub facilitates the allosteric transition of Clr4 from an inactive apo conformation to a hyperactive "catalyzing state", accompanied by conformational changes in the C-SET-insertion (SI) region, complete release of the autoregulatory loop (ARL), and retraction of the {beta}9/10 loop. Finally, we propose a structural model for the Clr4 catalytic-regulatory cycle, depicting varying levels of conformational regulation mediated by automethylation and ubiquitination. This work provides structural insights into the interplay between different histone modifications and their collective impact on epigenetic regulation.

molecular biology↗

Growth and defence in a unicellular microalga: the coexistence of r and K strategies

r (high reproductivity but stress-sensitive offspring) and K (low reproductivity but high stress-resistant offspring) strategies are two classical life history theories. Contrary to the belief that one species only has a single strategy (i.e., either r or K), we present experimental evidence for the coexistence of both strategies in the isogenic microalga Haematococcus lacustris. Under standard conditions, swimming vegetative cells (SVC) normally grew and divided via binary fission (r strategy) and gradually shifted into non-swimming cysts (NSC) over time. Intriguingly, unlike the prevailing notion that NSC cannot propagate under stress, they were found to reproduce via multiple fission at a barely detectable growth rate, resulting in stress-resistant, non-mobile daughter cells and demonstrating a complete life history (K strategy). Collectively, our findings indicate that H. lacustris adopts both r and K strategies throughout its life history. This research enhances the understanding of the adaptation and survival of microbial populations in changing environments.

ecology↗

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↗

Comparative Characterization of Bronchial and Nasal Mucus Reveals Key Determinants of Influenza A Virus Inhibition

Differentiated primary human respiratory epithelial cells grown at air-liquid interface have become a widely used cell culture model of the human conducting airways. These cultures contain secretory cells such as goblet and club cells, which produce and secrete mucus. Here, we characterize the composition of mucus harvested from airway cultures of nasal and bronchial origin. We find that despite inter-donor variability, the salt, sugar, lipid, and protein content and composition are very similar between nasal and bronchial mucus. However, subtle differences in the abundance of individual components in nasal versus bronchial mucus can influence its antimicrobial properties: The ability of mucus to neutralize influenza A virus varies with the anatomical origin of the airway cultures and correlates with the abundance of triglycerides and sialylated glycoproteins and glycolipids. ImportanceRespiratory mucus plays an important role during the transmission and infection process of microbes in the human respiratory tract. In case of influenza A virus, mucus stabilizes virions in infectious respiratory particles and droplets but hampers virus particles before they reach the respiratory epithelium through its physicochemical properties and the presence of sialylated decoy receptors. However, it is thus far not well understood which components of mucus mediate protection and inhibition. Our study now provides a comprehensive analysis of bronchial and nasal mucus from primary human airway cultures that can be used as a resource for future experimental designs and interpretations.

microbiology↗

Leveraging large language models for metabolic engineering design

Establishing efficient cell factories involves a continuous process of trial and error due to the intricate nature of metabolism. This complexity makes predicting effective engineering targets a challenging task. Therefore, it is vital to learn from the accumulated successes of previous designs for advancing future cell factory development. In this study, we developed a method based on large language models (LLMs) to extract metabolic engineering strategies from research articles on a large scale. We created a database containing over 29006 metabolic engineering entries, 1210 products and 751 organisms. Using this extracted data, we trained a hybrid model combining deep learning and mechanistic approaches to predict engineering targets. Our model outperformed traditional metabolic engineering target prediction algorithms, excelled in predicting the effects of gene modifications, and generalized well to out-of-distribution products and multiple gene combinations. Our study provides a valuable dataset, a chatbot, and an engineering target prediction model for the metabolic engineering field and exemplifies an efficient method for leveraging existing knowledge for future predictions.

systems biology↗

Dynamic cycles between idea generation and evaluation during creative storytelling

Many theories support the notion that creative thinking involves a dynamic transition between idea generation and evaluation, but there is limited evidence of how these two stages interact. The dual process model proposes that spontaneous thinking and deliberate thinking drive these stages and the transitions between them, but there is a debate over whether they operate in parallel or in sequence. To address these gaps, we conducted a functional magnetic resonance imaging (fMRI) study in 41 college students during a creative storytelling task. By analyzing the dynamic brain state, we link the brain states with idea generation and evaluation. The transition patterns between brain states provide evidence for dynamic circulation between idea generation and evaluation during creative storytelling. Using a deep learning approach, we demonstrate an alternating interaction between spontaneous and deliberate thinking, driving the idea generation and evaluation stages and the transitions between them. These findings deepen our understanding of the cognitive and neural mechanisms underlying creative thinking.

neuroscience↗