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Du, J.

Publications and source records attributed to Du, J..

At least 181 records · Page 10Linked to original sources

An ultrasensitive GRAB sensor for detecting extracellular ATP in vitro and in vivo

The purinergic transmitter ATP (adenosine 5-triphosphate) plays an essential role in both the central and peripheral nervous systems, and the ability to directly measure extracellular ATP in real time will increase our understanding of its physiological functions. We developed an ultrasensitive GPCR Activation-Based ATP sensor called GRABATP1.0, with a robust fluorescence response to extracellular ATP when expressed in several cell types. This sensor has sub-second kinetics, ATP affinity in the range of tens of nanomolar, and can be used to localize ATP release with subcellular resolution. Using this sensor, we monitored ATP release under a variety of in vitro and in vivo conditions, including primary hippocampal neurons, a zebrafish model of injury-induced ATP release, and LPS-induced ATP-release events in individual astrocytes in the mouse cortex measured using in vivo two-photon imaging. Thus, the GRABATP1.0 sensor is a sensitive, versatile tool for monitoring ATP release and dynamics under both physiological and pathophysiological conditions.

neuroscience↗

Super-Resolution Label-free Volumetric Vibrational Imaging

Innovations in high-resolution optical imaging have allowed visualization of nanoscale biological structures and connections. However, super-resolution fluorescence techniques, including both optics-oriented and sample-expansion based, are limited in quantification and throughput especially in tissues from photobleaching or quenching of the fluorophores, and low-efficiency or non-uniform delivery of the probes. Here, we report a general sample-expansion vibrational imaging strategy, termed VISTA, for scalable label-free high-resolution interrogations of protein-rich biological structures with resolution down to 82 nm. VISTA achieves decent three-dimensional image quality through optimal retention of endogenous proteins, isotropic sample expansion, and deprivation of scattering lipids. Free from probe-labeling associated issues, VISTA offers unbiased and high-throughput tissue investigations. With correlative VISTA and immunofluorescence, we further validated the imaging specificity of VISTA and trained an image-segmentation model for label-free multi-component and volumetric prediction of nucleus, blood vessels, neuronal cells and dendrites in complex mouse brain tissues. VISTA could hence open new avenues for versatile biomedical studies.

neuroscience↗

Proton receptors regulate synapse-specific reconsolidation in the amygdala

When an extinction procedure is performed within the reconsolidation window, the original aversive memory can be replaced by one that is less traumatic. Recent studies revealed that carbon dioxide (CO2) inhalation during retrieval enhances memory lability. However, the effects of CO2 inhalation on the central nervous system can be extensive, and there is lack of evidence suggesting that the effects of CO2 are selective to a reactivated memory. We discovered that CO2 inhalation paired with memory retrieval potentiates the specific aversive memory trace, resulting in greater memory lability. The specific effects of CO2 depend on acid-sensing ion channels (ASICs), the proton receptors that are involved in synaptic transmission and plasticity in the amygdala. In addition, CO2 inhalation alters memory lability via synaptic plasticity at selectively targeted synapses. Overall, our results suggest that inhaling CO2 during the retrieval event increases the lability of an aversive memory through a synapse-specific reconsolidation process.

neuroscience↗

DenovoProfiling: a webserver for de novo generated molecule library profiling

With the advances of deep learning techniques, various architectures for molecular generation have been proposed for de novo drug design. Successful cases from academia and industrial demonstrated that the deep learning based de novo molecular design could efficiently accelerate the drug discovery process. The flourish of the de novo molecular generation methods and applications created great demand for the visualization and functional profiling for the de novo generated molecules. The rising of publicly available chemogenomic databases lays good foundations and create good opportunities for comprehensive profiling of the de novo library. In this paper, we present DenovoProfiling, a web server dedicated for de novo library visualization and functional profiling. Currently, DenovoProfiling contains six modules: (1) identification & visualization, (2) chemical space, (3) scaffold analysis, (4) molecular alignment, (5) target & pathways, and (6) drugs mapping. DenovoProfiling could provide structural identification, chemical space exploration, drugs mapping, and targets & pathways. The comprehensive annotated information could give user a clear picture of their de novo library and could provide guidance in the further selection of candidates for synthesis and biological confirmation. DenovoProfiling is freely available at http://denovoprofiling.xielab.net.

bioinformatics↗

Coupling of H3K27me3 recognition with transcriptional repression through the BAH-PHD-CPL2 complex in Arabidopsis

Histone 3 Lys 27 trimethylation (H3K27me3)-mediated epigenetic silencing plays a critical role in multiple biological processes. However, the H3K27me3 recognition and transcriptional repression mechanisms are only partially understood. Here, we report a new mechanism for H3K27me3 recognition and transcriptional repression. Our structural and biochemical data showed that the BAH domain protein AIPP3 and the PHD proteins AIPP2 and PAIPP2 cooperate to read H3K27me3 and unmodified H3K4 histone marks, respectively, in Arabidopsis. The BAH-PHD bivalent histone reader complex silences a substantial subset of H3K27me3-enriched loci, including a number of development and stress response-related genes such as the RNA silencing effector gene ARGONAUTE 5 (AGO5) and We found that the BAH-PHD module associates with CPL2, a plant-specific Pol II carboxyl terminal domain (CTD) phosphatase, to form the BAH-PHD-CPL2 complex (BPC) for transcriptional repression. The BPC complex represses transcription through CPL2-mediated CTD dephosphorylation, thereby causing inhibition of Pol II release from the transcriptional start site. Our work reveals a mechanism coupling H3K27me3 recognition with transcriptional repression through the alteration of Pol II phosphorylation states, thereby contributing to our understanding of the mechanism of H3K27me3-dependent silencing.

plant biology↗

Modulation of Transient receptor potential melastatin 3 by protons through its intracellular binding sites

Transient receptor potential melastatin 3 channel (TRPM3) is a calcium-permeable nonselective cation channel that plays an important role in modulating glucose homeostasis in the pancreatic beta cells. However, how TRPM3 is regulated under physiological and pathological conditions is poorly understood. In this study, we found that both intracellular and extracellular protons block TRPM3 through its intracellular binding sites. We demonstrated that external protons indirectly block TRPM3, whereas internal protons inhibit TRPM3 directly with an inhibitory pH50 of 6.9 {+/-} 0.11. We identified three titratable residues, D1059, D1062, and D1073, at the inner vestibule of the channel pore that contribute to pH sensitivity. The mutation of D1073Q reduces TRPM3 current intensity and pH sensitivity; Replacement of Asp 1073 by Gln 1073 changes the reduction of TRPM3 outward current by low external pH 5.5, from 62 {+/-} 3 % in WT to 25 {+/-} 6.0 % in D1073Q. These results indicate that D1073 is not only essential for intracellular pH sensitivity, but it is also crucial for TRPM3 channel gating. In addition, a single mutation of D1059 or D1062 enhances pH sensitivity. In summary, our findings provide a novel molecular determinant for pH regulation of TRPM3. The inhibition of TRPM3 by protons may indicate an endogenous mechanism governing TRPM3 gating and its physiological/ pathological functions.

pharmacology and toxicology↗

MicroRNA775 Promotes Intrinsic Leaf Size and Reduces Cell Wall Pectin Level via a Target Galactosyltransferase in Arabidopsis

Plants possess unique primary cell walls made of complex polysaccharides that play critical roles in determining intrinsic cell and organ size. How genes responsible for synthesizing and modifying the polysaccharides are regulated by microRNAs (miRNAs) to control plant size remains largely unexplored. Here we identified 23 putative cell wall related miRNAs, termed CW-miRNAs, in Arabidopsis thaliana and characterized miR775 as an example. We showed that miR775 post-transcriptionally silences GALT9, which encodes an endomembrane-located galactosyltransferase belonging to the glycosyltransferase 31 family. Over-expression of miR775 and deletion of GALT9 significantly enlarged leaf-related organs, primarily owing to increases in cell size. Monosaccharide quantification, confocal Raman imaging, and immunolabelling combined with atomic force microscopy (AFM) revealed that the MIR775A-GALT9 circuit modulates pectin level and elastic modulus of the cell wall. We further showed that MIR775A is directly repressed by the transcription factor ELONGATED HYPOCOTYL 5 (HY5). Genetic analysis confirmed that HY5 is a negative regulator of leaf size and acts through the HY5-MIR775A-GALT9 repression cascade to control pectin level. These results demonstrate that miR775-regulated cell wall remodeling is an integral determinant for intrinsic leaf size in A. thaliana and highlight the need to study other CW-miRNAs for more insights into cell wall biology.

plant biology↗

MicroRNA-224 Promotes Cell Migration and Invasion by Targeting HOXA5 expression in Hepatocellular Carcinoma

MicroRNAs (miRNAs) are involved in the regulation of multiple cellular pathways and play a key role in the development and progression of tumor. Based on the cellular function of their targets, miRNAs play the role of oncogenes or tumor suppressor genes. Multiple studies have shown that abnormal expression of miRNAs has close relation with the incidence of HCC, but the mechanism of miRNAs in HCC still needs further research. In the present study, we showed that the overexpression of miR-224 can reduce the mRNA and protein expression of ADAM17 and HOXA5, the silencing of miR-224 can increase the protein expression of ADAM17 and HOXA5. Dual luciferase reporter assays showed that miR-224 can directly regulate the expression of ADAM17 and HOXA5. Importantly, we found that miR-224 positively regulates cell migration and invasion in HCC, miR-224 overexpression can promote the migration and invasion of BEL-7402 cell, and miR-224 silencing can suppress the migration and invasion of BEL-7402 cell. miR-224 overexpression can result in the redistribution of cell cycle, the cell percentage of S phase was increased significantly, the cell percentage of G1 phase was decreased significantly, and there is no noticeable change for the cell percentage of G2 phase. These results demonstrated that it may be exert the function of oncogenes in a particular link of cancer cell growth. In conclusion, these results suggest that miR-224 will become a promising biological target in the treatment strategy of hepatocellular carcinoma (HCC).

cancer biology↗

Kinetics of Plasma cfDNA Predicts Clinical Response in Non-Small Cell Lung Cancer Patients

BackgroundTyrosine Kinases Inhibitors (TKIs), VEGF/VEGF receptor inhibitors (VEGFIs, bevacizumab) and immune checkpoint inhibitors (ICIs) have revolutionized the treatment of advanced cancer including non-small-cell lung cancer (NSCLC). Cell-free DNA (cfDNA) has been adapted as a convenient liquid biopsy that reflects characteristics of the status of both the primary and metastatic tumors, assisting in personalized medicine. This study aims to evaluate the utility of cfDNA as a prognostic biomarker and efficacy predictor of chemotherapy with or without these precision therapies in NSCLC patients. MethodsPeripheral cfDNA levels were quantified in 154 patients with NSCLC before (baseline) and after (post-chemotherapy) the first target cycle of chemotherapy. These patients were divided into four subgroups receiving chemotherapy only, chemotherapy plus TKIs, chemotherapy plus VEGFIs, and chemotherapy plus immune checkpoint inhibitors (ICIs), respectively. The correlations of cfDNA with tumor burden, clinical characteristics, progression-free survival (PFS), objective response ratio (ORR), and therapy regimens were analyzed. ResultsBaseline cfDNA, but not post-chemotherapy, positively correlates with tumor burden. cfDNA Ratio (post-chemotherapy/baseline) well distinguished responsive individuals (CR/PR) from non-responsive patients (PD/SD). Additionally, cfDNA Ratio was found to be negatively correlated with PFS in lung adenocarcinoma (LUAD), but not in lung squamous-cell carcinoma (LUSC). LUAD patients with low cfDNA Ratio benefit significantly including prolonged PFS and improved ORR, compared with those with high cfDNA Ratio. When stratified by therapy regimen, the predictive value of cfDNA Ratio is significant in patients with chemotherapy plus VEGFIs. ConclusionThe kinetics of plasma cfDNA during the chemotherapy may function as a prognostic biomarker and efficacy predictor for NSCLC patients.

cancer biology↗

Loss of Nupr1 promotes engraftment by tuning the dormancy threshold of hematopoietic stem cell repository via regulating p53-checkpoint pathway

Hematopoietic stem cells (HSCs) are dominantly quiescent under homeostasis, which is a key mechanism of maintaining the HSC pool for life-long hematopoiesis. Dormant HSCs poise to be immediately activated on urgent conditions and can return to quiescence after regaining homeostasis. To date, the molecular networks of regulating the threshold of HSC dormancy, if exist, remain largely unknown. Here, we unveiled that deletion of Nupr1, a gene preferentially expressed in HSCs, activated the quiescence HSCs under homeostatic status, which conferred engraftment competitive advantage on HSCs without compromising their stemness and multi-lineage differentiation abilities in serial transplantation settings. Following an expansion protocol, the Nupr1-/- HSCs proliferate more robustly than their wild type counterparts in vitro. Nupr1 inhibits the expression of p53 and the rescue of which offsets the engraftment advantage. Our data unveil the de novo role of Nupr1 as an HSC quiescence-regulator, which provides insights into accelerating the engraftment efficacy of HSC transplantation by targeting the HSC quiescence-controlling network.

cell biology↗

Binding of guide piRNA triggers methylation of the unstructured N-terminal region of Aub leading to assembly of the piRNA amplification complex

Piwi proteins use guide piRNAs to repress selfish genomic elements, protecting the genomic integrity of gametes and ensuring the fertility of animal species. Efficient transposon repression depends on amplification of piRNA guides in the ping-pong cycle, which in Drosophila entails tight cooperation between two Piwi proteins, Aub and Ago3. Here we show that post-translational modification, symmetric dimethylarginine (sDMA), of Aub is essential for piRNA biogenesis, transposon silencing and fertility. Methylation is triggered by loading of a piRNA guide into Aub, which exposes its unstructured N-terminal region to the PRMT5 methylosome complex. Thus, sDMA modification is a signal that Aub is loaded with piRNA guide. Amplification of piRNA in the ping-pong cycle requires assembly of a tertiary complex scaffolded by Krimper, which simultaneously binds the N-terminal regions of Aub and Ago3. To promote generation of new piRNA, Krimp uses its two Tudor domains to bind Aub and Ago3 in opposite modification and piRNA-loading states. Our results reveal that post-translational modifications in unstructured regions of Piwi proteins and their binding by Tudor domains that are capable of discriminating between modification states is essential for piRNA biogenesis and silencing. HighlightsO_LIsDMA modification of Aub is essential for ping-pong cycle, transposon silencing and fertility. C_LIO_LIpiRNA loading triggers Aub sDMA modification by exposing its unstructured N terminal region to the methylosome complex. C_LIO_LIA single molecule of Krimp simultaneously binds piRNA-bound Aub and empty Ago3 to assemble ping-pong complex. C_LIO_LIThe distinct structure of two Tudor domains of Krimp ensures binding of Ago3 and Aub in opposite modification and piRNA-loading states. C_LI

biochemistry↗

COVID-19 Variants Database: A repository for Human SARS-CoV-2 Polymorphism Data

COVID-19 is a newly communicable disease with a catastrophe outbreak that affects all over the world. We retrieved about 8,781 nucleotide fragments and complete genomes of SARS-CoV-2 reported from sixty-four countries. The CoV-2 reference genome was obtained from the National Genomics Data Center (NGDC), GISAID, and NCBI Genbank. All the sequences were aligned against reference genomes using Clustal Omega and variants were called using in-house built Python script. We intend to establish a user-friendly online resource to visualize the variants in the viral genome along with the Primer Infopedia. After analyzing and filtering the data globally, it was made available to the public. The detail of data available to the public includes mutations from 5688 SARS-CoV-2 sequences curated from 91 regions. This database incorporated 39920 mutations over 3990 unique positions. According to the translational impact, these mutations include 11829 synonymous mutations including 681 synonymous frameshifts and 21701 nonsynonymous mutations including 10 nonsynonymous frameshifts. Development of SARS-CoV-2 mutation genome browsers is a fundamental step obliging towards the virus surveillance, viral detection, and development of vaccine and therapeutic drugs. The SARS-COV-2 mutation browser is available at http://covid-19.dnageography.com.

genomics↗

An emerging role of Prevotella histicola on estrogen-deficiency induced bone loss through the gut microbiota-bone axis

Gut microbiota (GM)-bone axis has emerged as a crucial mediator in the maintenance of bone homeostasis. Estrogen-deficiency induced bone loss is closely associated with an altered GM. However, the underlying mechanisms remain not fully understood. To this end, feces samples collected from the postmenopausal patients with osteoporosis (PMO) and with normal bone mass (PMN) were examined by 16s rRNA gene sequencing. We found that GM in PMO group was featured by a significant decreased proportion of genus Prevotella in comparison with that in the PMN group. Next, Prevotella histicola (P.histicola), a typical specie of Prevotella, was orally given to the mice following the ovariectomy (OVX) procedure and it significantly prevented OVX induced bone loss. Mechanistically, the protective effects of P.histicola on bone mass were found to be associated with the inhibition of osteoclastic resorption by attenuating osteoclastogenic cytokines expression and ameliorating gut permeability. Thus, P.histicola may prevent estrogen-deficiency induced bone loss through the GM-bone axis.

microbiology↗

AMP-activated-kinase (AMPK) is essential sensor and metabolic regulator of retinal neurons and their integrated metabolism with RPE.

The retina has one of the highest energy demands in the human body, and proper regulation of metabolism among the cell types of the retina is required for functional vision. Recent studies have reported that retinal metabolism is disrupted during retinal degeneration and aging, while therapies designed to enhance metabolism can slow or prevent degeneration. Here, we show that multiple metabolic pathways, including those regulated by a key ATP sensor and regulator of metabolism, AMP-activated-kinase (AMPK), were dysregulated in a model of inherited retinal degeneration. In order to assess the direct role of AMPK in regulating retinal metabolism, we used mice with retina-specific knockout of AMPK activity. Conditional loss of AMPK resulted in impaired visual function at an early age, with slow photoreceptor loss observed in older mice. Moreover, we found that loss of AMPK resulted in decreased metabolic flux from glucose, decreased mitochondrial DNA copy number, decreased mitochondrial-related gene expression, and alterations in mitochondrial morphology in the photoreceptors, all of which preceded degeneration. Surprisingly, metabolic changes from the loss of AMPK in retinal neurons also resulted in secondary degeneration of retinal pigment epithelial (RPE) cells. Together, these data show that AMPK signaling is important for maintaining metabolic homeostasis of the retina and support the hypothesis that photoreceptors and RPE have a shared metabolic ecosystem that is controlled, in part, by AMPK.

neuroscience↗

A Novel Xenonucleic Acid Mediated Molecular Clamping Technology for Early Colorectal Cancer Screening

BackgroundColorectal cancer (CRC) is one of the leading causes of cancer-related death. Early detection is critical to reduce CRC morbidity and mortality. In order to meet this need, we developed a molecular clamping assay called the ColoScape for early colorectal cancer diagnostics. MethodsNineteen mutations in four genes APC, KRAS, BRAF and CTNNB1 associated with early events in CRC pathogenesis are targeted in the ColoScape assay. Xenonucleic Acid (XNA) mediated qPCR clamping technology was applied to minimize the wild-type background amplification in order to improve assay sensitivity of CRC mutation detection. The assay analytical performance was verified and validated, cfDNA and FFPE CRC patient samples were evaluated, and a ROC cure was applied to evaluate its performance. ResultsThe data showed that the assay analytical sensitivity is 0.5% Variant Allele Frequency, corresponding to ~7-8 copies of mutant DNA with 5ng total DNA input per test. This assay is highly reproducible with intra-assay CV <3% and inter-assay <5%. We have investigated 380 clinical samples including plasma cfDNA and FFPE samples from patients with precancerous and different stages of CRC. The preliminary assay clinical specificity and sensitivity for CRC cfDNA were 100% (95% CI, 80.3-97.5%) and 92.2% (95% CI, 94.7-100%) respectively with AUC being about 0.96; and 96% (95% CI, 77.6-99.7%) specificity and 92% (95% CI, 86.1-95.6%) sensitivity with AUC 0.94 for CRC FFPE; and 95% specificity (95% CI, 82.5%-99.1%) and 62.5% sensitivity (95% CI, 35.8%-83.7%) with AUC 0.79 for precancerous lesions cfDNA. ConclusionsXNA mediated molecular clamping assay is a rapid, precise, and sensitive assay for the detection of precancerous lesions cfDNA and CRC cfDNA or FFPE samples.

cancer biology↗

Inhibition of mitochondrial respiration impairs nutrient consumption and metabolite transport in human retinal pigment epithelium

Mitochondrial respiration in mammalian cells not only generates ATP to meet their own energy needs but also couples with biosynthetic pathways to produce metabolites that can be exported to support neighboring cells. However, how defects in mitochondrial respiration influence these biosynthetic and exporting pathways remains poorly understood. Mitochondrial dysfunction in retinal pigment epithelium (RPE) cells is an emerging contributor to the death of their neighboring photoreceptors in degenerative retinal diseases including age-related macular degeneration. In this study, we used targeted-metabolomics and 13C tracing to investigate how inhibition of mitochondrial respiration influences the intracellular and extracellular metabolome. We found inhibition of mitochondrial respiration strikingly influenced both the intracellular and extracellular metabolome in primary RPE cells. Intriguingly, the extracellular metabolic changes sensitively reflected the intracellular changes. These changes included substantially enhanced glucose consumption and lactate production, reduced release of pyruvate, citrate and ketone bodies, and massive accumulation of multiple amino acids and nucleosides. In conclusion, these findings reveal a metabolic signature of nutrient consumption and release in mitochondrial dysfunction in RPE cells. Testing medium metabolites provides a sensitive and noninvasive method to assess mitochondrial function in nutrient utilization and transport.

biochemistry↗

Reference-free and de novo Identification of Circular RNAs

BackgroundEarly studies have unveiled multiple regulatory functions of circular RNAs (circRNAs); however, accurate detection and quantification of circRNAs, especially in understudied organisms, is unsolved yet. ResultsIn this study, we developed a new reference-free method, namely Cirit, to de novo detect circRNAs with sequence support from the next generation sequencing (NGS) transcriptome. The Cirit showed remarkable performance in accurate detection and quantification of circRNAs via comparing with current methods from different aspects. Using Cirit, we detected 28,813 nonredundant human circRNAs from 91 transcriptome datasets, as well as 2,385 circRNAs from four understudied organisms. Subsequent analyses found that the majority of human circRNAs expressed spatiotemporally; only a very small portion of circRNAs were back-splice junction (BSJ)-consistent (maximally 5.17%) or sequence-consistent (under 2%). Furthermore, circRNA genesis were relatively flexible that only about 60% of human circRNAs used the canonical GT-AG pattern for back-splice. The inconsistent expression of circRNAs challenges their roles as precise transcriptional regulators. ConclusionsIn summary, the reference-free method provides a straightforward and universal way for reliable circRNA research. It will largely boost the successful rate in designing highly specific probes to monitor circRNA behavior in cell. In particular, it brings circRNA research to the organisms that have no genome or draft genome.

bioinformatics↗

Blocking antibodies against SARS-CoV-2 RBD isolated from a phage display antibody library using a competitive biopanning strategy

The infection of the novel coronavirus SARS-CoV-2 have caused more than 150,000 deaths, but no vaccine or specific therapeutic antibody is currently available. SARS-CoV-2 relies on its spike protein, in particular the receptor binding domain (RBD), to bind human cell receptor angiotensin-converting enzyme 2 (ACE2) for viral entry, and thus targeting RBD holds the promise for preventing SARS-CoV-2 infection. In this work, a competitive biopanning strategy of a phage display antibody library was applied to screen blocking antibodies against RBD. High-affinity antibodies were enriched after the first round using a standard panning process in which RBD-His recombinant protein was immobilized as a bait. At the next two rounds, immobilized ACE2-Fc and free RBD-His proteins were mixed with the enriched phage antibodies. Antibodies binding to RBD at epitopes different from ACE2-binding site were captured by the immobilized ACE2-Fc, forming a "sandwich" complex. Only antibodies competed with ACE2 for recognizing RBD at the same or similar epitopes can bind to the free RBD-His in the supernatant and be subsequently separated by the Ni-NTA magnetic beads. Top 1 lead from the competitive biopanning of a synthetic antibody library, Lib AB1, was produced as the full-length IgG1 format. It was proved to competitively block the binding of RBD to ACE2 protein, and potently inhibit SARS-CoV-2 pseudovirus infection of ACE2-overexpressing Hela cells with IC50 values of 12nM. Nevertheless, top 1 lead from the standard biopanning of Lib AB1, can only bind to RBD in vitro but not have the blocking or neutralization activity. Our strategy can efficiently isolate the blocking antibodies of RBD, and it would speed up the discovery of neutralizing antibodies against SARS-CoV-2.

microbiology↗